Analysis of Factors Influencing Extended Post Anesthesia Care Unit Length of Stay (PACU-LOS) in Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy

Analysis of Factors Influencing Extended Post Anesthesia Care Unit Length of Stay (PACU-LOS) in Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Analysis of Factors Influencing Extended Post Anesthesia Care Unit Length of Stay (PACU-LOS) in Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy Xiaoqing Zhang, Bin Wei, Jing Zhang, Xiangyang Guo, Min Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7678845/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Mar, 2026 Read the published version in Obesity Surgery → Version 1 posted 10 You are reading this latest preprint version Abstract Background The post anesthesia recovery phase following bariatric surgery is a high-risk period characterized by increased susceptibility to respiratory and hemodynamic complications, warranting prolonged monitoring and targeted interventions. Despite advancements in perioperative care, the identification of risk factors for extended recovery remains a critical unmet need in obese populations. Methods This single-center retrospective study analyzed 169 consecutive patients undergoing laparoscopic sleeve gastrectomy for metabolic syndrome and extubated in post anesthesia care unit (PACU) at Peking University Third Hospital (2015–2025). Patients were stratified by PACU length of stay (LOS) into extended (≥ 42 min, 75th percentile) and control (< 42 min) groups. Comprehensive perioperative variables were evaluated, including ‌preoperative data of demographic profiles, ASA physical status, BMI, obesity surgery mortality risk score (OS-MRS), and obstructive sleep apnea syndrome (OSAS) comorbidity; ‌Intraoperative and postoperative‌ data including procedure duration, hypoxemia incidence, pain scores, number of rescue antiemetic administered, postoperative complications, reoperation rates, length of hospital stay, 30-day readmission rates and mortality. Univariate analysis and logistic regression analysis. Were performed to find the risk factors of prolonged LOS. Results The extended PACU-LOS group (n = 45, 26.6%) demonstrated significantly higher BMI (40.6 [38.1, 47.2] vs. 38.7 [34.9, 44.0] kg/m², p = 0.007), ASA III prevalence (66.7%% vs 25.8%, p < 0.001), existence of OSAS (71.1% vs. 33.1%, p < 0.001), intraoperative peak P ET CO 2 (41 [39, 46] vs. 39 [36, 42] p < 0.001) and post-extubation hypoxemia incidence (62.2% vs. 9.7%, p < 0.001). Multivariate analysis identified three independent predictors: post-extubation hypoxemia ( OR = 14.771, 95% CI : 5.557 ~ 39.268), ASA III ( OR = 3.924, 95% CI : 1.362 ~ 11.304), and OSAS ( OR = 3.122, 95% CI :1.091 ~ 8.934). Conclusion ASA III classification, preexisting OSAS, and post-extubation hypoxemia independently predict extended PACU-LOS in patients undergone laparoscopic sleeve gastrectomy. These findings underscore the imperative for preoperative risk stratification using standardized scoring systems, protocolized post-extubation oxygenation strategies, and resource allocation for high-dependency monitoring in at-risk patients. Obesity Sleeve gastrectomy Anesthesia PACU length of stay Figures Figure 1 Introduction Obesity represents a significant national and global health challenge, posing a major public health concern in our country. According to data from The Lancet , the global prevalence of overweight and obesity has risen dramatically from 1990 to 2021, with a 155.1% increase in men and a 104.9% increase in women. By 2050, it is projected that the number of overweight and obese individuals worldwide will reach 3.8 billion, accounting for over half of the global adult population. In 2021, China reported 402 million overweight and obese individuals, making it the country with the highest number of such cases globally [1, 2]. Obese patients frequently present with metabolic syndrome, which serves as an independent predictor of cardiac dysfunction and cardiovascular diseases, as well as a risk factor for perioperative morbidity and mortality [3]. Bariatric surgery has been shown to significantly reduce patient weight and mitigate or improve obesity-related risks and complications [4]. With the ongoing advancement of Enhanced Recovery After Surgery (ERAS) protocols, bariatric surgery patients can now be discharged on the first postoperative day or even on the day of surgery [5, 6], presenting numerous challenges for anesthesia management. Patients are often not fully conscious post-anesthesia, and their organ functions remain unstable [7]. Therefore, enhanced monitoring for high-risk patients and extended monitoring periods when necessary are critical. Morbidly obese patients frequently exhibit unique airway conditions and medical comorbidities, and a high body fat percentage can lead to drug accumulation, resulting in various complications during the anesthesia recovery period, including unplanned reintubation and unplanned transfers to the ICU. These issues prolong monitoring time, increase anesthesia management risks, significantly compromise patient safety, and extend post-anesthesia care unit (PACU) turnover time. This study retrospectively analyzed obese patients who underwent laparoscopic sleeve gastrectomy at our institution from January 1, 2015, to January 31, 2025, aiming to identify risk factors associated with prolonged PACU length of stay. The findings provide evidence and guidance for identifying high-risk patients, enhancing anesthesia management during the recovery period, and ensuring clinical safety. 1. Clinical Data and Methods 1.1 General Information This study was approved by the Ethics Committee of Peking University Third Hospital (Approval No. 2025; Medical Ethics Review 179-01), with patients informed consents waived. Inclusion criteria were as follows: age ≥ 18 years, indications for bariatric surgery, and an Aldrete score ≥ 9 and a NRS pain score ≤ 3 before been discharged from PACU. Exclusion criteria included incomplete clinical data, patients admitted but not undergoing surgery, patients transferred to the ICU with tracheal intubation, and patients who declined participation. A total of 169 cases were included, comprising 53 males and 116 females, with a median age of 32 (27, 38) years and a median BMI of 40 (36, 45) kg/m². According to the American Society of Anesthesiologists (ASA) classification, 107 cases were grade II, and 62 cases were grade III. 73 cases were complicated with obstructive sleep apnea syndrome (OSAS). We also recorded the patients’ Obesity Surgery Mortality Risk Score (OS-MRS) which includes BMI > 50 kg/m², male gender, age > 45 years, hypertension, previous risk factors for pulmonary embolism (e.g., history of venous thromboembolism, placement of an inferior vena cava filter), hypoventilation (sleep-disordered breathing), or pulmonary hypertension [ 8 ]. Patients were divided into two groups based on whether PACU length of stay (PACU-LOS) (observation time after extubation until returning to the ward) was extended (≥ the 75th percentile of the PACU-LOS [ 9 ]). The prolonged group included 45 cases, and the control group included 124 cases. The grouping process is illustrated in Fig. 1 . 1.2 Methods A retrospective review of bariatric surgery cases was conducted using the surgical anesthesia record system at Peking University Third Hospital. The study cohort included patients admitted to the Department of General Surgery between ‌January 1, 2015 and January 31, 2025‌. During the initial screening, two independent researchers identified 180 eligible anesthesia records, and 2 duplicate cases were excluded (patients rescheduled due to uncontrolled hypertension). All patients underwent laparoscopic sleeve gastrectomy, including 16 cases (8.9%) underwent concurrent surgeries (cholecystectomy/hysteroscopy). For postoperative care, 9 patients were transferred to ICU, and the remaining 169 cases (93.9%) with standard postoperative course. The patient flow diagram (Fig. 1 ) illustrates the case selection process and outcomes. For all eligible patients, a comprehensive review of electronic medical records was conducted to document: ‌demographic and clinical characteristics‌ of gender, age, body mass index (BMI), diagnosis of OSAS, comorbid conditions including hypertension, diabetes mellitus, coronary artery disease, asthma, renal insufficiency, depression, and OS-MRS. ‌Surgical outcomes‌ including surgical approach/technique, intraoperative blood loss, duration of surgery, length of hospital stay, postoperative complications, reoperation rates, 30-day readmission rates and mortality. ‌Anesthesia-related parameters‌ were extracted from surgical anesthesia records and PACU documentation, including ASA physical status classification, time intervals including tracheal intubation time (from induction drug administration to successful intubation), emergence time (from discontinuation of maintenance anesthesia to extubation), post-extubation observation period (from extubation to ward transfer), intraoperative fluid administration volume, peak end-tidal carbon dioxide partial pressure (P Et CO 2 ), airway/respiratory adverse events (difficult intubation, emergency airway management, aspiration events, post-extubation airway obstruction, reintubation requirements), postoperative emergence agitation, post-extubation hypoxemia (SpO 2 <90% on room air) [10]. All enrolled patients completed a self-reported questionnaire to assess pain levels, which were quantified using the numerical rating scale (NRS), ranging from 0 (no pain) to 10 (extreme pain). NRS scores were noted prior to administration of rescue analgesia, and patients were discharged when NRS pain score ≤ 4 [11]. 1.3 Statistical Analysis All analyses were performed using ‌SPSS 24.0‌ (IBM Corp., Armonk, NY, USA). Continuous variables were assessed for normality using Shapiro-Wilk tests. ‌Normally distributed data were presented as Mean ± standard deviation ( X ± SD ) and analyzed with ‌independent samples t -tests.‌Non-normally distributed data‌ were presented as median with interquartile range M [ P 25 , P 75 ] and analyzed with ‌Mann-Whitney U tests.‌ For ‌categorical data handling,‌ frequency comparisons utilized ‌Pearson's chi-square tests‌. For ‌multivariable modeling‌, all clinically relevant variables were initially evaluated for association with prolonged PACU-LOS with ‌univariate analysis. Variables that showed statistically significant associations in the univariate analysis were subsequently included in a binary logistic regression analysis to identify independent predictors. A two-tailed P -value < 0.05 was considered statistically significant for all analyses. 2. Results A total of 169 patients were enrolled in this study, with 64 cases classified as ASA III and the remaining as ASA II. 73 patients had preexisting OSAS. The distribution of OS-MRS scores is detailed in Table 1 . The surgical procedures demonstrated the following key metrics (median [IQR]): ‌procedure duration was 138 (100, 179) minutes, tracheal intubation time was 4 (4, 5) minutes, ‌emergence time‌ was 11 (8, 17) minutes, PACU-LOS after extubation was 31 (20, 42) minutes, and ‌peak intraoperative P Et CO₂‌was 40 (37, 43) mmHg. ‌The intraoperative‌fluid administration‌ was 1600 (1100, 2100) mL, the ‌estimated blood loss was 20 (10, 30) mL, and post-extubation ‌hypoxemia incidence‌ occurred in 42 cases. All patients received multimodal analgesia consisting of pre-closure local wound infiltration, NSAIDs administration, supplemental regional techniques with transversus abdominis plane blocks, and/or patient-controlled intravenous analgesia. No patients experienced postoperative delirium or agitation, and no airway or respiratory management-related adverse events were reported. The hospital stay was 7 (6, 8) days, with 0% readmission rate, 0% reoperation rate, and 0% mortality in 30-day outcome. Table 1 Univariate analysis of extended PACU-LOS during the anesthesia recovery period after tracheal tube extubation​​. Variable Extended PACU-LOS Group (n = 45) Control Group (n = 124) χ² OR (95% CI ) P -value Male sex 19 (42%) 34 (27%) 0.051 Age (yr) 31 (27, 36) 32.5 (27, 38) 0.179 BMI (kg/m²) 40.6 (38.1, 47.2) 38.7 (34.9, 44.0) 0.007* ASA III grade a 30 (66.7%) 32(25.8) 23.73 0.174 (0.08 ~ 0.36) < 0.001* OSAS 32 (71.1%) 41(33.1%) 20.79 0.185 (0.09 ~ 0.40) < 0.001* OS-MRS 4.428 0.514 0 9 (20.0%) 20 (16.1%) 1 10 (22.2%) 42 (33.9%) 2 14 (32.1%) 30 (24.2%) 3 10 (22.2%) 23 (18.5%) 4 1 (2.2%) 8 (64.5%) 5 1 (2.2%) 1 (0.8%) Intraoperative peak P ET CO 2 (mmHg) 41 (39, 46) 39 (36, 42) 0.001* Procedure duration (min) 121 (98, 165.5) 141 (101.25, 189.75) 0.085 Intubation time (min) 4 (4, 5) 4.5 (4, 5) 0.939 Emergence time (min) 14 (4, 48) 12 (3, 40) 0.125 Hypoxemia 28 (62.2%) 14 (9.7%) 45.86 0.08 (0.03 ~ 0.18) < 0.001* PONV 8 (17.8%) 14 (11.3%) 1.227 0.589 (0.23 ~ 1.52) 0.268 NRS b 3 (2, 5) 3.5 (2, 5) 0.986 ‌Length of hospital stay (days) 7 (6, 8.5) 7 (6, 8) 0.600 PACU-LOS, post-anesthesia care unit length of stay. BMI, body mass index; ASA, American Society of Anesthesiology; OSAS, obstructive sleep apnea syndrome; OS-MRS, Obesity Surgery Mortality Risk Score; P ET CO 2 , end-tidal carbon dioxide partial pressure; PONV, postoperative nausea and vomiting; NRS, Numerical Rating Scale. NRS scores were noted prior to administration of rescue analgesia, and patients were discharged when NRS pain score ≤ 4. a , All patients were classified into ASA III grade and ASA II grade groups. b , Pain levels were evaluated using the numerical rating scale (NRS), ranging from 0 to 10. * P < 0.05 indicates statistical significance. Patients were stratified into two groups based on whether their PACU-LOS was ≥ 42 minutes. The prolonged group (n = 45, ≥ 42 minutes) and the control group (n = 124, < 42 minutes). The median PACU length of stay after extubation was significantly longer in the prolonged group [47 (43, 58) minutes] versus controls [25 (17, 32) minutes]. Univariate analysis demonstrated significant intergroup differences in BMI, ASA classification, post-extubation hypoxemia, OSAS prevalence, and P Et CO 2 values (all P < 0.05) (Table 1 ). Logistic regression analysis revealed that ASA classification ( OR = 3.924, 95% CI : 1.362 ~ 11.304, P = 0.011), presence of OSAS ( OR = 3.122, 95% CI : 1.091 ~ 8.934, P = 0.0034), and post-extubation hypoxemia ( OR = 14.771, 95% CI : 5.557 ~ 39.268, P < 0.001) were independent factors associated with prolonged anesthesia recovery time (Table 2 ). Table 2 Logistic Regression Analysis of Prolonged Post-extubation Observation Period​​. Variable Regression coefficient β (standard error) Wald test Odds ratio (95% CI ) P -value BMI 0.055 (0.035) 2.453 1.057 (0.986 ~ 1.133) 0.117 P ET CO₂ -0.077 (0.041) 3.456 0.926 (0.854 ~ 1.004) 0.063 OSAS 1.138 (0.536) 4.517 3.122 (1.091 ~ 8.934) 0.034* Hypoxemia 2.693 (0.499) 29.089 14.771(5.557 ~ 39.268) < 0.001* ASA grade 1.367(0.540) 6.417 3.924 (1.362 ~ 11.304) 0.011* Constant -1.186 (2.175) 0.297 0.586 BMI, body mass index; ASA, American Society of Anesthesiology; P ET CO₂, end-tidal carbon dioxide partial pressure; OSAS, obstructive sleep apnea syndrome. β , relating coefficient to probability; CI, confidence interval * P < 0.05 indicates statistical significance. 3. Discussion After anesthesia and tracheal extubation, patients require close monitoring to ensure a safe transition through the recovery period. Common adverse events in the PACU include nausea and vomiting, reflux aspiration, cardiovascular events, hypoxemia, incision pain, and postoperative delirium. This study identified ASA classification, post-extubation hypoxemia, and pre-existing OSAS as independent predictors of prolonged PACU-LOS. The present findings corroborate the critical need for stratified postoperative monitoring in bariatric surgical patients, particularly during the high-risk transition period following tracheal extubation. 3.1 Ventilation and Respiratory Function-Related Issues The Univariate analysis revealed three clinically significant respiratory predictors of delayed PACU discharge: pre-existing OSAS, elevated intraoperative P Et CO 2 , and post-extubation hypoxemia. These findings corroborate the pathophysiological cascade wherein surgical pneumoperitoneum and anesthetic residuals compound the baseline respiratory compromise in obesity. Wang et al. reported a 37%–46% incidence of postoperative respiratory depression, with nearly 75% of severe cases resulting in brain damage or death [ 12 ]. Obese patients, with their low oxygen reserves and poor hypoxia tolerance, are particularly susceptible to hypoxemia after extubation, which, if unaddressed, can lead to hypoxic brain injury or death [ 13 , 14 ]. Excessive fat deposition in the head, neck, and oropharynx narrows the upper airway in morbidly obese patients. Reduced lung volume, increased atelectasis, decreased lung and chest wall compliance, and elevated airway resistance further compromise ventilation. Abdominal surgery and pneumoperitoneum exacerbate respiratory dysfunction, increasing the risk of postoperative respiratory complications and acute respiratory failure. Therefore, obese patients should be placed in a semi-sitting position post-extubation [ 15 , 16 ]. Anesthesiologists must remain vigilant for hypoxemia during recovery, employing prolonged observation and active oxygen therapy to maintain SpO 2 above 96% during transfer [ 17 ]. Patients with preoperative OSAS are at high risk for perioperative complications, particularly respiratory events, which are associated with increased cardiopulmonary morbidity and mortality [ 18 ]. Morbidly obese patients, especially those with OSAS, face a higher risk of respiratory failure, hypoxia, and apnea [ 19 ]. This study confirmed that OSAS prolongs recovery time. Inadequate monitoring and incomplete anesthetic clearance increase the risk of respiratory depression in OSAS patients, necessitating close observation and attention to ventilation to prevent adverse events. While intraoperative P Et CO 2 differed significantly between groups ( P < 0.001), logistic regression did not identify it as a factor for prolonged recovery. High diffusivity of CO 2 allows rapid clearance postoperatively unless ventilation is impaired. However, hypoxemia often accompanies CO 2 retention [ 19 ]. Routine CO 2 monitoring post-extubation is not yet standard at our center, limiting our understanding of its impact. High oxygenation during transfer may suppress hypoxic drive, leading to hypercapnia. Continuous cardiorespiratory monitoring should be maintained for high-risk patients, and immediate application of positive airway pressure is indicated if oxygenation cannot be maintained post-extubation [ 20 , 21 ]. 3.2 ASA, OS-MRS, and BMI in Relation to Anesthesia Risk Existing evidence establishes a relationship between elevated ASA physical status classification (≥ III) and OS-MRS scores with prolonged PACU stay duration [ 22 ]. Higher ASA grades predict postoperative pulmonary complications in abdominal surgery. Patients with higher ASA grades have a reduced ability to tolerate surgery and anesthesia. Additionally, during the perioperative period, general anesthesia can impair respiratory muscle function and mucociliary clearance, while neuromuscular blocking agents may increase respiratory muscle load, further compromising pulmonary function. These factors elevate the risk of postoperative atelectasis, bronchial collapse, and other pulmonary complications. ASA grade is significantly associated with the incidence of postoperative pulmonary complications [ 23 ]. Our findings align with these reports. Although OS-MRS retains prognostic value for 30-day mortality in bariatric populations, its discriminative capacity for morbidity endpoints remains disputed, particularly regarding respiratory complications [ 18 ]. In this study, OS-MRS scores did not differ significantly between groups. Shapses M. suggested that ASA classification, reflecting systemic comorbidities and functional status, provides superior risk stratification compared to unidimensional scoring systems [ 24 ]. Although the ASA physical status classification is widely used, its inter-rater reliability is suboptimal. Therefore, the implementation of standardized training programs for anesthesia providers is imperative to improve consistency. Critical respiratory events during emergence predominantly stem from reduced pharyngeal cross-sectional area, increased closing pressure, and impaired respiratory drive, necessitating reintubation [ 14 – 16 ]. Concerns about perioperative risks in obese patients often focus on obesity itself, yet evidence suggests that increased BMI alone does not elevate perioperative risk. The “obesity paradox” describes lower mortality in obese patients, though this remains controversial. The types of fat, its distribution, and muscle mass also influence perioperative risks, complicating BMI-based assessments [ 25 ]. In this study, while BMI differed between groups (P = 0.007), it was not an independent risk factor for prolonged recovery. However, it is noteworthy that parmacokinetic alterations in obesity—characterized by increased volume of distribution for lipophilic agents and delayed clearance—might create risks for context-sensitive half-time prolongation and postoperative drug redistribution which may adversely impacted the quality of emergence. Obesity is often associated with difficult intubation, but studies suggest it is not an independent risk factor [ 18 ]. Young adult bariatric patients typically have good maximal mouth opening and neck mobility, reducing the incidence of difficult intubation. However, difficult mask ventilation is more common in obese patients [ 26 ]. This study lacked data on difficult mask ventilation during induction. Time from induction to intubation and from drug cessation to extubation did not differ between groups, likely due to advanced airway management devices like video laryngoscopes, stylets, and augmented reality laryngoscope, which improve first-attempt success rates [ 27 ]. 3.3 Nausea and Vomiting Postoperative nausea and vomiting (PONV) adversely affect patient satisfaction and can lead to dehydration, electrolyte imbalance, aspiration, pneumothorax, hypoxia, esophageal rupture, increased intracranial pressure, wound complications, delayed oral intake, prolonged hospitalization, and increased costs [ 28 ]. PONV is the most common complication after bariatric surgery, with an incidence exceeding 80% in some procedures, and a significant contributor to prolonged recovery [ 29 ]. Anesthetic factors like opioid use and surgical factors such as pneumoperitoneum-induced vagal excitation and reduced gastric capacity contribute to PONV [ 30 ]. Given its multifactorial etiology, a multimodal approach targeting different receptor sites is recommended for high-risk patients. Our center employs proactive measures, including preoperative or intraoperative administration of 5-HT 3 receptor antagonists, NK-1 receptor antagonists, corticosteroids, metoclopramide, phenothiazines, antihistamines, and anticholinergics, alone or in combination, to reduce PONV incidence and severity [ 31 ]. For patients experiencing PONV during recovery, additional antiemetics with different mechanisms are administered. Multimodal interventions improve patient comfort and reduce PONV [ 32 ]. Opioid-sparing techniques, such as local infiltration anesthesia, transversus abdominis plane blocks, and non-steroidal anti-inflammatory drugs, minimize opioid-related side effects. Effective gastric suction during surgery prevents distension and reduces PONV risk. 4. Conclusion In summary, ASA physical status, OSAS, and post-extubation hypoxemia were identified as independent predictors of prolonged PACU-LOS in bariatric surgery patients. Under the ERAS-Integrated Management Protocol, high-risk patients should receive mandatory extended monitoring with continuous capnography until normocapnia, adequate inspiratory effort, and stable oxygenation are achieved. Conversely, low-risk patients qualify for fast-track discharge upon meeting the following criteria: Modified Aldrete score ≥ 9, inspiratory capacity ≥ 80% of preoperative baseline, and train-of-four (TOF) ratio ≥ 0.9. This risk-stratified approach optimizes PACU throughput while maintaining patient safety. Study limitations include the single-center design and absence of standardized hypoxemia management protocols. Future multicenter studies are warranted to evaluate whether the implementation of risk-stratified recovery algorithms reduces PACU-LOS without compromising patient safety. 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Cite Share Download PDF Status: Published Journal Publication published 04 Mar, 2026 Read the published version in Obesity Surgery → Version 1 posted Editorial decision: Revision requested 21 Oct, 2025 Reviews received at journal 14 Oct, 2025 Reviews received at journal 14 Oct, 2025 Reviewers agreed at journal 14 Oct, 2025 Reviewers agreed at journal 13 Oct, 2025 Reviewers agreed at journal 13 Oct, 2025 Reviewers invited by journal 12 Oct, 2025 Editor assigned by journal 07 Oct, 2025 Submission checks completed at journal 03 Oct, 2025 First submitted to journal 22 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7678845","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":533075478,"identity":"2d703eba-e74f-46c8-80f2-96e9ba823a90","order_by":0,"name":"Xiaoqing Zhang","email":"","orcid":"","institution":"Peking University Third Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaoqing","middleName":"","lastName":"Zhang","suffix":""},{"id":533075480,"identity":"eb9542db-3433-4bc8-93bd-ee1d39856dde","order_by":1,"name":"Bin Wei","email":"","orcid":"","institution":"Peking University Third 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15:44:16","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":89632,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7678845/v1/7e5d1b80e9176c7f01bf7768.html"},{"id":94473252,"identity":"8b4e8dad-783d-4656-96ee-48b921088ba3","added_by":"auto","created_at":"2025-10-27 15:43:39","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":101378,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of patient enrollment and group allocation.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7678845/v1/9dc898faa899c03d127330b6.png"},{"id":104250783,"identity":"8e0be699-9e73-4002-a527-86a7f710faaa","added_by":"auto","created_at":"2026-03-09 16:08:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":815269,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7678845/v1/79c5781c-9484-4b42-bf9d-b1d32c846a9d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Analysis of Factors Influencing Extended Post Anesthesia Care Unit Length of Stay (PACU-LOS) in Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy","fulltext":[{"header":"Introduction","content":"\u003cp\u003eObesity represents a significant national and global health challenge, posing a major public health concern in our country. According to data from\u0026nbsp;\u003cem\u003eThe Lancet\u003c/em\u003e, the global prevalence of overweight and obesity has risen dramatically from 1990 to 2021, with a 155.1% increase in men and a 104.9% increase in women. By 2050, it is projected that the number of overweight and obese individuals worldwide will reach 3.8 billion, accounting for over half of the global adult population. In 2021, China reported 402 million overweight and obese individuals, making it the country with the highest number of such cases globally [1, 2]. Obese patients frequently present with metabolic syndrome, which serves as an independent predictor of cardiac dysfunction and cardiovascular diseases, as well as a risk factor for perioperative morbidity and mortality [3]. Bariatric surgery has been shown to significantly reduce patient weight and mitigate or improve obesity-related risks and complications [4].\u003c/p\u003e\n\u003cp\u003eWith the ongoing advancement of Enhanced Recovery After Surgery (ERAS) protocols, bariatric surgery patients can now be discharged on the first postoperative day or even on the day of surgery [5, 6], presenting numerous challenges for anesthesia management. Patients are often not fully conscious post-anesthesia, and their organ functions remain unstable [7]. Therefore, enhanced monitoring for high-risk patients and extended monitoring periods when necessary are critical. Morbidly obese patients frequently exhibit unique airway conditions and medical comorbidities, and a high body fat percentage can lead to drug accumulation, resulting in various complications during the anesthesia recovery period, including unplanned reintubation and unplanned transfers to the ICU. These issues prolong monitoring time, increase anesthesia management risks, significantly compromise patient safety, and extend post-anesthesia care unit (PACU) turnover time. This study retrospectively analyzed obese patients who underwent laparoscopic sleeve gastrectomy at our institution from January 1, 2015, to January 31, 2025, aiming to identify risk factors associated with prolonged PACU length of stay. The findings provide evidence and guidance for identifying high-risk patients, enhancing anesthesia management during the recovery period, and ensuring clinical safety.\u003c/p\u003e"},{"header":"1. Clinical Data and Methods","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e\u003ch2\u003e1.1 General Information\u003c/h2\u003e\u003cp\u003e This study was approved by the Ethics Committee of Peking University Third Hospital (Approval No. 2025; Medical Ethics Review 179-01), with patients informed consents waived. Inclusion criteria were as follows: age\u0026thinsp;\u0026ge;\u0026thinsp;18 years, indications for bariatric surgery, and an Aldrete score\u0026thinsp;\u0026ge;\u0026thinsp;9 and a NRS pain score\u0026thinsp;\u0026le;\u0026thinsp;3 before been discharged from PACU. Exclusion criteria included incomplete clinical data, patients admitted but not undergoing surgery, patients transferred to the ICU with tracheal intubation, and patients who declined participation. A total of 169 cases were included, comprising 53 males and 116 females, with a median age of 32 (27, 38) years and a median BMI of 40 (36, 45) kg/m\u0026sup2;. According to the American Society of Anesthesiologists (ASA) classification, 107 cases were grade II, and 62 cases were grade III. 73 cases were complicated with obstructive sleep apnea syndrome (OSAS). We also recorded the patients\u0026rsquo; Obesity Surgery Mortality Risk Score (OS-MRS) which includes BMI\u0026thinsp;\u0026gt;\u0026thinsp;50 kg/m\u0026sup2;, male gender, age\u0026thinsp;\u0026gt;\u0026thinsp;45 years, hypertension, previous risk factors for pulmonary embolism (e.g., history of venous thromboembolism, placement of an inferior vena cava filter), hypoventilation (sleep-disordered breathing), or pulmonary hypertension [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Patients were divided into two groups based on whether PACU length of stay (PACU-LOS) (observation time after extubation until returning to the ward) was extended (\u0026ge;\u0026thinsp;the 75th percentile of the PACU-LOS [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]). The prolonged group included 45 cases, and the control group included 124 cases. The grouping process is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e1.2 Methods\u003c/h2\u003e\u003cp\u003eA retrospective review of bariatric surgery cases was conducted using the surgical anesthesia record system at Peking University Third Hospital. The study cohort included patients admitted to the Department of General Surgery between \u0026zwnj;January 1, 2015 and January 31, 2025\u0026zwnj;.\u003c/p\u003e\u003cp\u003eDuring the initial screening, two independent researchers identified 180 eligible anesthesia records, and 2 duplicate cases were excluded (patients rescheduled due to uncontrolled hypertension). All patients underwent laparoscopic sleeve gastrectomy, including 16 cases (8.9%) underwent concurrent surgeries (cholecystectomy/hysteroscopy). For postoperative care, 9 patients were transferred to ICU, and the remaining 169 cases (93.9%) with standard postoperative course. The patient flow diagram (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) illustrates the case selection process and outcomes.\u003c/p\u003e\u003cp\u003eFor all eligible patients, a comprehensive review of electronic medical records was conducted to document: \u0026zwnj;demographic and clinical characteristics\u0026zwnj; of gender, age, body mass index (BMI), diagnosis of OSAS, comorbid conditions including hypertension, diabetes mellitus, coronary artery disease, asthma, renal insufficiency, depression, and OS-MRS. \u0026zwnj;Surgical outcomes\u0026zwnj; including surgical approach/technique, intraoperative blood loss, duration of surgery, length of hospital stay, postoperative complications, reoperation rates, 30-day readmission rates and mortality.\u003c/p\u003e\u003cp\u003e\u0026zwnj;Anesthesia-related parameters\u0026zwnj; were extracted from surgical anesthesia records and PACU documentation, including ASA physical status classification, time intervals including tracheal intubation time (from induction drug administration to successful intubation), emergence time (from discontinuation of maintenance anesthesia to extubation), post-extubation observation period (from extubation to ward transfer), intraoperative fluid administration volume, peak end-tidal carbon dioxide partial pressure (P\u003csub\u003eEt\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e), airway/respiratory adverse events (difficult intubation, emergency airway management, aspiration events, post-extubation airway obstruction, reintubation requirements), postoperative emergence agitation, post-extubation hypoxemia (SpO\u003csub\u003e2\u003c/sub\u003e\u0026lt;90% on room air) [10]. All enrolled patients completed a self-reported questionnaire to assess pain levels, which were quantified using the numerical rating scale (NRS), ranging from 0 (no pain) to 10 (extreme pain). NRS scores were noted prior to administration of rescue analgesia, and patients were discharged when NRS pain score\u0026thinsp;\u0026le;\u0026thinsp;4 [11].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e1.3 Statistical Analysis\u003c/h2\u003e\u003cp\u003eAll analyses were performed using \u0026zwnj;SPSS 24.0\u0026zwnj; (IBM Corp., Armonk, NY, USA). Continuous variables were assessed for normality using Shapiro-Wilk tests. \u0026zwnj;Normally distributed data were presented as Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (\u003cem\u003eX\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/em\u003e) and analyzed with \u0026zwnj;independent samples \u003cem\u003et\u003c/em\u003e-tests.\u0026zwnj;Non-normally distributed data\u0026zwnj; were presented as median with interquartile range \u003cem\u003eM\u003c/em\u003e [\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003e25\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003e75\u003c/em\u003e\u003c/sub\u003e] and analyzed with \u003cem\u003e\u0026zwnj;Mann-Whitney U\u003c/em\u003e tests.\u0026zwnj; For \u0026zwnj;categorical data handling,\u0026zwnj; frequency comparisons utilized \u003cem\u003e\u0026zwnj;Pearson's chi-square\u003c/em\u003e tests\u0026zwnj;. For \u0026zwnj;multivariable modeling\u0026zwnj;, all clinically relevant variables were initially evaluated for association with prolonged PACU-LOS with \u0026zwnj;univariate analysis. Variables that showed statistically significant associations in the univariate analysis were subsequently included in a \u003cem\u003ebinary logistic regression\u003c/em\u003e analysis to identify independent predictors. A two-tailed \u003cem\u003eP\u003c/em\u003e-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant for all analyses.\u003c/p\u003e\u003c/div\u003e"},{"header":"2. Results","content":"\u003cp\u003eA total of 169 patients were enrolled in this study, with 64 cases classified as ASA III and the remaining as ASA II. 73 patients had preexisting OSAS. The distribution of OS-MRS scores is detailed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The surgical procedures demonstrated the following key metrics (median [IQR]): \u0026zwnj;procedure duration was 138 (100, 179) minutes, tracheal intubation time was 4 (4, 5) minutes, \u0026zwnj;emergence time\u0026zwnj; was 11 (8, 17) minutes, PACU-LOS after extubation was 31 (20, 42) minutes, and \u0026zwnj;peak intraoperative P\u003csub\u003eEt\u003c/sub\u003eCO₂\u0026zwnj;was 40 (37, 43) mmHg. \u0026zwnj;The intraoperative\u0026zwnj;fluid administration\u0026zwnj; was 1600 (1100, 2100) mL, the \u0026zwnj;estimated blood loss was 20 (10, 30) mL, and post-extubation \u0026zwnj;hypoxemia incidence\u0026zwnj; occurred in 42 cases. All patients received multimodal analgesia consisting of pre-closure local wound infiltration, NSAIDs administration, supplemental regional techniques with transversus abdominis plane blocks, and/or patient-controlled intravenous analgesia. No patients experienced postoperative delirium or agitation, and no airway or respiratory management-related adverse events were reported. The hospital stay was 7 (6, 8) days, with 0% readmission rate, 0% reoperation rate, and 0% mortality in 30-day outcome.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eUnivariate analysis of extended PACU-LOS during the anesthesia recovery period after tracheal tube extubation​​.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eExtended PACU-LOS Group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;45)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl Group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;124)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eχ\u0026sup2;\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eOR (95% \u003cem\u003eCI\u003c/em\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale sex\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e19 (42%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e34 (27%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.051\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (yr)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e31 (27, 36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e32.5 (27, 38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.179\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBMI (kg/m\u0026sup2;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40.6 (38.1, 47.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e38.7 (34.9, 44.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.007*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eASA III grade \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 (66.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e32(25.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e23.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.174 (0.08\u0026thinsp;~\u0026thinsp;0.36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOSAS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e32 (71.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41(33.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e20.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.185 (0.09\u0026thinsp;~\u0026thinsp;0.40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOS-MRS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4.428\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.514\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9 (20.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20 (16.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10 (22.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e42 (33.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14 (32.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e30 (24.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10 (22.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23 (18.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (2.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8 (64.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (2.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (0.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIntraoperative peak P\u003csub\u003eET\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e (mmHg)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41 (39, 46)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39 (36, 42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.001*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProcedure duration (min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e121 (98, 165.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e141 (101.25, 189.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.085\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIntubation time (min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4 (4, 5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.5 (4, 5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.939\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEmergence time (min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14 (4, 48)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12 (3, 40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.125\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypoxemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28 (62.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (9.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e45.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.08 (0.03\u0026thinsp;~\u0026thinsp;0.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePONV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (17.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (11.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.227\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.589 (0.23\u0026thinsp;~\u0026thinsp;1.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.268\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNRS \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (2, 5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.5 (2, 5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.986\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026zwnj;Length of hospital stay (days)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7 (6, 8.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 (6, 8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.600\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003ePACU-LOS, post-anesthesia care unit length of stay. BMI, body mass index; ASA, American Society of Anesthesiology; OSAS, obstructive sleep apnea syndrome; OS-MRS, Obesity Surgery Mortality Risk Score; P\u003csub\u003eET\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e, end-tidal carbon dioxide partial pressure; PONV, postoperative nausea and vomiting; NRS, Numerical Rating Scale. NRS scores were noted prior to administration of rescue analgesia, and patients were discharged when NRS pain score\u0026thinsp;\u0026le;\u0026thinsp;4.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003e, All patients were classified into ASA III grade and ASA II grade groups.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003eb\u003c/sup\u003e, Pain levels were evaluated using the numerical rating scale (NRS), ranging from 0 to 10.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistical significance.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ePatients were stratified into two groups based on whether their PACU-LOS was \u0026ge;\u0026thinsp;42 minutes. The prolonged group (n\u0026thinsp;=\u0026thinsp;45, \u0026ge;\u0026thinsp;42 minutes) and the control group (n\u0026thinsp;=\u0026thinsp;124, \u0026lt;\u0026thinsp;42 minutes). The median PACU length of stay after extubation was significantly longer in the prolonged group [47 (43, 58) minutes] versus controls [25 (17, 32) minutes]. \u003cem\u003eUnivariate analysis\u003c/em\u003e demonstrated significant intergroup differences in BMI, ASA classification, post-extubation hypoxemia, OSAS prevalence, and P\u003csub\u003eEt\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e values (all \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). \u003cem\u003eLogistic regression\u003c/em\u003e analysis revealed that ASA classification (\u003cem\u003eOR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.924, 95% \u003cem\u003eCI\u003c/em\u003e: 1.362\u0026thinsp;~\u0026thinsp;11.304, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.011), presence of OSAS (\u003cem\u003eOR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.122, 95% \u003cem\u003eCI\u003c/em\u003e: 1.091\u0026thinsp;~\u0026thinsp;8.934, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0034), and post-extubation hypoxemia (\u003cem\u003eOR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;14.771, 95% \u003cem\u003eCI\u003c/em\u003e: 5.557\u0026thinsp;~\u0026thinsp;39.268, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were independent factors associated with prolonged anesthesia recovery time (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eLogistic Regression Analysis of Prolonged Post-extubation Observation Period​​.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRegression coefficient \u003cem\u003eβ\u003c/em\u003e\u003c/p\u003e\u003cp\u003e(standard error)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eWald\u003c/em\u003e test\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eOdds ratio (95% \u003cem\u003eCI\u003c/em\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBMI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.055 (0.035)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.453\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.057 (0.986\u0026thinsp;~\u0026thinsp;1.133)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.117\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eP\u003csub\u003eET\u003c/sub\u003eCO₂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-0.077 (0.041)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.456\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.926 (0.854\u0026thinsp;~\u0026thinsp;1.004)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.063\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOSAS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.138 (0.536)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4.517\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.122 (1.091\u0026thinsp;~\u0026thinsp;8.934)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.034*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypoxemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.693 (0.499)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e29.089\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e14.771(5.557\u0026thinsp;~\u0026thinsp;39.268)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eASA grade\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.367(0.540)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e6.417\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.924 (1.362\u0026thinsp;~\u0026thinsp;11.304)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.011*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eConstant\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-1.186 (2.175)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.297\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.586\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eBMI, body mass index; ASA, American Society of Anesthesiology; P\u003csub\u003eET\u003c/sub\u003eCO₂, end-tidal carbon dioxide partial pressure; OSAS, obstructive sleep apnea syndrome.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eβ\u003c/em\u003e, relating coefficient to probability; CI, confidence interval\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistical significance.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"3. Discussion","content":"\u003cp\u003eAfter anesthesia and tracheal extubation, patients require close monitoring to ensure a safe transition through the recovery period. Common adverse events in the PACU include nausea and vomiting, reflux aspiration, cardiovascular events, hypoxemia, incision pain, and postoperative delirium. This study identified ASA classification, post-extubation hypoxemia, and pre-existing OSAS as independent predictors of prolonged PACU-LOS. The present findings corroborate the critical need for stratified postoperative monitoring in bariatric surgical patients, particularly during the high-risk transition period following tracheal extubation.\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Ventilation and Respiratory Function-Related Issues\u003c/h2\u003e\u003cp\u003eThe \u003cem\u003eUnivariate analysis\u003c/em\u003e revealed three clinically significant respiratory predictors of delayed PACU discharge: pre-existing OSAS, elevated intraoperative P\u003csub\u003eEt\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e, and post-extubation hypoxemia. These findings corroborate the pathophysiological cascade wherein surgical pneumoperitoneum and anesthetic residuals compound the baseline respiratory compromise in obesity. Wang et al. reported a 37%\u0026ndash;46% incidence of postoperative respiratory depression, with nearly 75% of severe cases resulting in brain damage or death [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Obese patients, with their low oxygen reserves and poor hypoxia tolerance, are particularly susceptible to hypoxemia after extubation, which, if unaddressed, can lead to hypoxic brain injury or death [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eExcessive fat deposition in the head, neck, and oropharynx narrows the upper airway in morbidly obese patients. Reduced lung volume, increased atelectasis, decreased lung and chest wall compliance, and elevated airway resistance further compromise ventilation. Abdominal surgery and pneumoperitoneum exacerbate respiratory dysfunction, increasing the risk of postoperative respiratory complications and acute respiratory failure. Therefore, obese patients should be placed in a semi-sitting position post-extubation [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Anesthesiologists must remain vigilant for hypoxemia during recovery, employing prolonged observation and active oxygen therapy to maintain SpO\u003csub\u003e2\u003c/sub\u003e above 96% during transfer [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePatients with preoperative OSAS are at high risk for perioperative complications, particularly respiratory events, which are associated with increased cardiopulmonary morbidity and mortality [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Morbidly obese patients, especially those with OSAS, face a higher risk of respiratory failure, hypoxia, and apnea [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. This study confirmed that OSAS prolongs recovery time. Inadequate monitoring and incomplete anesthetic clearance increase the risk of respiratory depression in OSAS patients, necessitating close observation and attention to ventilation to prevent adverse events.\u003c/p\u003e\u003cp\u003eWhile intraoperative P\u003csub\u003eEt\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e differed significantly between groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), \u003cem\u003elogistic regression\u003c/em\u003e did not identify it as a factor for prolonged recovery. High diffusivity of CO\u003csub\u003e2\u003c/sub\u003e allows rapid clearance postoperatively unless ventilation is impaired. However, hypoxemia often accompanies CO\u003csub\u003e2\u003c/sub\u003e retention [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Routine CO\u003csub\u003e2\u003c/sub\u003e monitoring post-extubation is not yet standard at our center, limiting our understanding of its impact. High oxygenation during transfer may suppress hypoxic drive, leading to hypercapnia. Continuous cardiorespiratory monitoring should be maintained for high-risk patients, and immediate application of positive airway pressure is indicated if oxygenation cannot be maintained post-extubation [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.2 ASA, OS-MRS, and BMI in Relation to Anesthesia Risk\u003c/h2\u003e\u003cp\u003eExisting evidence establishes a relationship between elevated ASA physical status classification (\u0026ge;\u0026thinsp;III) and OS-MRS scores with prolonged PACU stay duration [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Higher ASA grades predict postoperative pulmonary complications in abdominal surgery. Patients with higher ASA grades have a reduced ability to tolerate surgery and anesthesia. Additionally, during the perioperative period, general anesthesia can impair respiratory muscle function and mucociliary clearance, while neuromuscular blocking agents may increase respiratory muscle load, further compromising pulmonary function. These factors elevate the risk of postoperative atelectasis, bronchial collapse, and other pulmonary complications. ASA grade is significantly associated with the incidence of postoperative pulmonary complications [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Our findings align with these reports. Although OS-MRS retains prognostic value for 30-day mortality in bariatric populations, its discriminative capacity for morbidity endpoints remains disputed, particularly regarding respiratory complications [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In this study, OS-MRS scores did not differ significantly between groups. Shapses M. suggested that ASA classification, reflecting systemic comorbidities and functional status, provides superior risk stratification compared to unidimensional scoring systems [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Although the ASA physical status classification is widely used, its inter-rater reliability is suboptimal. Therefore, the implementation of standardized training programs for anesthesia providers is imperative to improve consistency.\u003c/p\u003e\u003cp\u003eCritical respiratory events during emergence predominantly stem from reduced pharyngeal cross-sectional area, increased closing pressure, and impaired respiratory drive, necessitating reintubation [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Concerns about perioperative risks in obese patients often focus on obesity itself, yet evidence suggests that increased BMI alone does not elevate perioperative risk. The \u0026ldquo;obesity paradox\u0026rdquo; describes lower mortality in obese patients, though this remains controversial. The types of fat, its distribution, and muscle mass also influence perioperative risks, complicating BMI-based assessments [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. In this study, while BMI differed between groups (P\u0026thinsp;=\u0026thinsp;0.007), it was not an independent risk factor for prolonged recovery. However, it is noteworthy that parmacokinetic alterations in obesity\u0026mdash;characterized by increased volume of distribution for lipophilic agents and delayed clearance\u0026mdash;might create risks for context-sensitive half-time prolongation and postoperative drug redistribution which may adversely impacted the quality of emergence.\u003c/p\u003e\u003cp\u003eObesity is often associated with difficult intubation, but studies suggest it is not an independent risk factor [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Young adult bariatric patients typically have good maximal mouth opening and neck mobility, reducing the incidence of difficult intubation. However, difficult mask ventilation is more common in obese patients [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. This study lacked data on difficult mask ventilation during induction. Time from induction to intubation and from drug cessation to extubation did not differ between groups, likely due to advanced airway management devices like video laryngoscopes, stylets, and augmented reality laryngoscope, which improve first-attempt success rates [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Nausea and Vomiting\u003c/h2\u003e\u003cp\u003ePostoperative nausea and vomiting (PONV) adversely affect patient satisfaction and can lead to dehydration, electrolyte imbalance, aspiration, pneumothorax, hypoxia, esophageal rupture, increased intracranial pressure, wound complications, delayed oral intake, prolonged hospitalization, and increased costs [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. PONV is the most common complication after bariatric surgery, with an incidence exceeding 80% in some procedures, and a significant contributor to prolonged recovery [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAnesthetic factors like opioid use and surgical factors such as pneumoperitoneum-induced vagal excitation and reduced gastric capacity contribute to PONV [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Given its multifactorial etiology, a multimodal approach targeting different receptor sites is recommended for high-risk patients. Our center employs proactive measures, including preoperative or intraoperative administration of 5-HT\u003csub\u003e3\u003c/sub\u003e receptor antagonists, NK-1 receptor antagonists, corticosteroids, metoclopramide, phenothiazines, antihistamines, and anticholinergics, alone or in combination, to reduce PONV incidence and severity [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. For patients experiencing PONV during recovery, additional antiemetics with different mechanisms are administered. Multimodal interventions improve patient comfort and reduce PONV [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Opioid-sparing techniques, such as local infiltration anesthesia, transversus abdominis plane blocks, and non-steroidal anti-inflammatory drugs, minimize opioid-related side effects. Effective gastric suction during surgery prevents distension and reduces PONV risk.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eIn summary, ASA physical status, OSAS, and post-extubation hypoxemia were identified as independent predictors of prolonged PACU-LOS in bariatric surgery patients. Under the ERAS-Integrated Management Protocol, high-risk patients should receive mandatory extended monitoring with continuous capnography until normocapnia, adequate inspiratory effort, and stable oxygenation are achieved. Conversely, low-risk patients qualify for fast-track discharge upon meeting the following criteria: Modified Aldrete score\u0026thinsp;\u0026ge;\u0026thinsp;9, inspiratory capacity\u0026thinsp;\u0026ge;\u0026thinsp;80% of preoperative baseline, and train-of-four (TOF) ratio\u0026thinsp;\u0026ge;\u0026thinsp;0.9. This risk-stratified approach optimizes PACU throughput while maintaining patient safety. Study limitations include the single-center design and absence of standardized hypoxemia management protocols. Future multicenter studies are warranted to evaluate whether the implementation of risk-stratified recovery algorithms reduces PACU-LOS without compromising patient safety.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eConsent for publication:\u003c/h2\u003e\u003cp\u003e All authors consent the publication of this article.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eDeclarations of interest\u003c/h2\u003e\n\u003cp\u003eNone.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eXiaoqing Zhang and Bin Wei contributed equally to this work.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003enone.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data generated or analyzed during this study are included in this published article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGBD 2021 Adult BMI Collaborators. Global, regional, and national prevalence of adult overweight and obesity, 1990\u0026ndash;2021, with forecasts to 2050: a forecasting study for the Global Burden of Disease Study 2021. Lancet. 2025;405(10481):813\u0026ndash;838. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S0140-6736(25)00355-1\u003c/span\u003e\u003cspan address=\"10.1016/S0140-6736(25)00355-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Epub 2025 Mar 3. PMID: 40049186.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePan XF, Wang L, Pan A. Epidemiology and determinants of obesity in China. Lancet Diabetes Endocrinol. 2021;9(6):373\u0026ndash;392. doi: 10.1016/S2213-8587(21)00045-0. Erratum in: Lancet Diabetes Endocrinol. 2021,9(7):e2.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePouwels S, Buise MP, Twardowski P, et al. Obesity Surgery and Anesthesiology Risks: a Review of Key Concepts and Related Physiology. Obes Surg. 2019,29(8):2670\u0026ndash;2677\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCarlin AM, Zeni TM, English WJ, et al. Michigan Bariatric Surgery Collaborative. The comparative effectiveness of sleeve gastrectomy, gastric bypass, and adjustable gastric banding procedures for the treatment of morbid obesity. Ann Surg. 2013;257(5):791\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLam J, Suzuki T, Bernstein D, et al. An ERAS protocol for bariatric surgery: is it safe to discharge on post-operative day 1? Surg Endosc. 2019,33(2):580\u0026ndash;586.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarinari G, Foletto M, Nagliati C, et al. Enhanced recovery after bariatric surgery: an Italian consensus statement. Surg Endosc. 2022,36(10):7171\u0026ndash;7186.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee LA, Caplan RA, Stephens LS, et al. Postoperative opioid-induced respiratory depression: a closed claims analysis. Anesthesiology. 2015,122(3):659\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArterburn D, Johnson ES, Butler MG, et al. Predicting 90-day mortality after bariatric surgery: an independent, external validation of the OS-MRS prognostic risk score. Surg Obes Relat Dis. 2014,10(5):774\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGabriel RA, Waterman RS, Kim J, et al. A Predictive Model for Extended Postanesthesia Care Unit Length of Stay in Outpatient Surgeries. Anesth Analg. 2017,124(5):1529\u0026ndash;1536.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun Z, Sessler DI, Dalton JE, et al. Postoperative Hypoxemia Is Common and Persistent: A Prospective Blinded Observational Study. Anesth Analg. 2015,121(3):709\u0026ndash;715.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChung F, Chan VW, Ong D. A post-anesthetic discharge scoring system for home readiness after ambulatory surgery. J Clin Anesth. 1995;7(6):500\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHaixia Wang, Huanrong Qiu, Kai Su, et al. Analysis of risk factors for delayed extubation after laparoscopic bariatric surgery in morbidly obese patients. 2022, 38(8):4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRivas E, Cohen B, Saasouh W, et al. Hypoventilation in the PACU is associated with hypoventilation in the surgical ward: Post-hoc analysis of a randomized clinical trial. J Clin Anesth. 2023;84:110989. Michele C, Francesco Z, Giovanna I, et al. Obesity and perioperative noninvasive ventilation in bariatric surgery.[J]. Minerva Chirurgica, 2017, 72(3):248\u0026ndash;264.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDosman JA, Karunanayake CP, Fenton M, et al. Obesity, Sex, Snoring and Severity of OSA in a First Nation Community in Saskatchewan, Canada. Clocks Sleep. 2022, 4(1):100\u0026ndash;113.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBinquan Tang, Yanmeng Zhu, Xianliang Xing, et al. Effect of tracheal extubation in the lateral position of 15\u003csup\u003e\u0026deg;\u003c/sup\u003e head high slope on respiratory function in obese patients during general anesthesia recovery. 2020, 36(8):4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLabaste F, Silva S, Serin-Moulin L, et al. Predictors of desaturation during patient transport to the postoperative anesthesia care unit: an observational study. J Clin Anesth. 2016,35:210\u0026ndash;214\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDohrn N, Sommer T, Bisgaard J,et al. Difficult Tracheal Intubation in Obese Gastric Bypass patients. Obes Surg. 2016,26(11):2640\u0026ndash;2647.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGarc\u0026iacute;a-Garc\u0026iacute;a ML, Mart\u0026iacute;n-Lorenzo JG, Lir\u0026oacute;n-Ruiz R, et al. Failure of the Obesity Surgery Mortality Risk Score (OS-MR S) to Predict Postoperative Complications After Bariatric Surgery. A Single-Center Series and Systematic Review. Obes Surg. 2017,27(6):1423\u0026ndash;1429.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeng J, Balouch M, Mooney A, et al. A capnography and transcutaneous CO\u003csub\u003e2\u003c/sub\u003e profile of bariatric patients during early postoperative period after opioid-sparing anesthesia. Surg Obes Relat Dis. 2021,17(5):963\u0026ndash;967\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRoesslein M, Chung F. Obstructive sleep apnoea in adults: peri-operative considerations: A narrative review. Eur J Anaesthesiol. 2018,35(4):245\u0026ndash;255.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeingarten TN, Sprung J. Review of Postoperative Respiratory Depression: From Recovery Room to General Care Unit. Anesthesiology. 2022,137(6):735\u0026ndash;741.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXiaoqing zhang, Jiechu Wang, Jing Zhang, et al.Preliminary Analysis on Relevant Factors of Prolonged Observation Time During the Recovery Period After Laparoscopic Sleeve Gastrectomy in Obese Patients. Chinese Journal of Minimally Invasive Surgery, 2023,23(2):81\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBo Chen, Ke Zhang, Mingshuai Yu. Construction of risk prediction model for postoperative pulmonary complications in patients undergoing abdominal surgery[J/OL]. Chinese Journal of Lung Diseases(Electronic Edition), 2021, 14(04): 502\u0026ndash;504.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShapses M, Tang L, Layne A, et al. Fatty Liver Is an Independent Risk Factor for Delayed Recovery from Anesthesia. Hepatol Commun. 2021,5(11):1848\u0026ndash;1859.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRothman KJ: BMI-related errors in the measurement of obesity. Int J Obes (Lond) 2008; 32 Suppl 3: S56\u0026ndash;59\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoon TS, Fox PE, Somasundaram A, et al. The influence of morbid obesity on difficult intubation and difficult mask ventilation. J Anesth. 2019,33(1):96\u0026ndash;102.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eParisi A, Desiderio J, Cirocchi R, et al. Enhanced Recovery after Surgery (ERAS): a Systematic Review of Randomised Controlled Trials (RCTs) in Bariatric Surgery. Obes Surg. 2020,30(12):5071\u0026ndash;5085.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eElvir-Lazo OL, White PF, Yumul R, et al. Management strategies for the treatment and prevention of postoperative/postdischarge nausea and vomiting: an updated review. F1000Res. 2020;9:F1000 Faculty Rev-983.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXiaozhuo Zheng, Ke Wei. Progress in managing Nausea and Vomiting Following Bariatric Surgery. J Clin Anesthesiol. 2021, 37(4):3.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKruthiventi SC, Hofer RE, Warner ME, et al. Postoperative nausea and vomiting after bariatric surgery and dexmedetomidine anesthetic: a propensity-weighted analysis. Surg Obes Relat Dis. 2020,16(4):545\u0026ndash;553.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAlghanem SM, Massad IM, Rashed EM, et al. Optimization of anesthesia antiemetic measures versus combination therapy using dexamethasone or ondansetron for the prevention of postoperative nausea and vomiting. Surg Endosc. 2010;24(2):353\u0026ndash;358.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMa K, Wu X, Chen Y, et al. Effect of multimodal intervention on postoperative nausea and vomiting in patients undergoing gynecological laparoscopy. J Int Med Res. 2019;47(5):2026\u0026ndash;2033.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"obesity-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"obsu","sideBox":"Learn more about [Obesity Surgery](https://link.springer.com/journal/11695)","snPcode":"11695","submissionUrl":"https://submission.springernature.com/new-submission/11695/3","title":"Obesity Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Obesity, Sleeve gastrectomy, Anesthesia, PACU length of stay","lastPublishedDoi":"10.21203/rs.3.rs-7678845/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7678845/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThe post anesthesia recovery phase following bariatric surgery is a high-risk period characterized by increased susceptibility to respiratory and hemodynamic complications, warranting prolonged monitoring and targeted interventions. Despite advancements in perioperative care, the identification of risk factors for extended recovery remains a critical unmet need in obese populations.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003e This single-center retrospective study analyzed 169 consecutive patients undergoing laparoscopic sleeve gastrectomy for metabolic syndrome and extubated in post anesthesia care unit (PACU) at Peking University Third Hospital (2015\u0026ndash;2025). Patients were stratified by PACU length of stay (LOS) into extended (\u0026ge;\u0026thinsp;42 min, 75th percentile) and control (\u0026lt;\u0026thinsp;42 min) groups. Comprehensive perioperative variables were evaluated, including \u0026zwnj;preoperative data of demographic profiles, ASA physical status, BMI, obesity surgery mortality risk score (OS-MRS), and obstructive sleep apnea syndrome (OSAS) comorbidity; \u0026zwnj;Intraoperative and postoperative\u0026zwnj; data including procedure duration, hypoxemia incidence, pain scores, number of rescue antiemetic administered, postoperative complications, reoperation rates, length of hospital stay, 30-day readmission rates and mortality. Univariate analysis and logistic regression analysis. Were performed to find the risk factors of prolonged LOS.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThe extended PACU-LOS group (n\u0026thinsp;=\u0026thinsp;45, 26.6%) demonstrated significantly higher BMI (40.6 [38.1, 47.2] \u003cem\u003evs.\u003c/em\u003e 38.7 [34.9, 44.0] kg/m\u0026sup2;, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007), ASA III prevalence (66.7%% vs 25.8%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), existence of OSAS (71.1% \u003cem\u003evs.\u003c/em\u003e 33.1%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), intraoperative peak P\u003csub\u003eET\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e (41 [39, 46] \u003cem\u003evs.\u003c/em\u003e39 [36, 42] \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and post-extubation hypoxemia incidence (62.2% \u003cem\u003evs.\u003c/em\u003e 9.7%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Multivariate analysis identified three independent predictors: post-extubation hypoxemia (\u003cem\u003eOR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;14.771, 95%\u003cem\u003eCI\u003c/em\u003e: 5.557\u0026thinsp;~\u0026thinsp;39.268), ASA III (\u003cem\u003eOR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.924, 95%\u003cem\u003eCI\u003c/em\u003e: 1.362\u0026thinsp;~\u0026thinsp;11.304), and OSAS (\u003cem\u003eOR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.122, 95%\u003cem\u003eCI\u003c/em\u003e:1.091\u0026thinsp;~\u0026thinsp;8.934).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eASA III classification, preexisting OSAS, and post-extubation hypoxemia independently predict extended PACU-LOS in patients undergone laparoscopic sleeve gastrectomy. These findings underscore the imperative for preoperative risk stratification using standardized scoring systems, protocolized post-extubation oxygenation strategies, and resource allocation for high-dependency monitoring in at-risk patients.\u003c/p\u003e","manuscriptTitle":"Analysis of Factors Influencing Extended Post Anesthesia Care Unit Length of Stay (PACU-LOS) in Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-27 14:26:57","doi":"10.21203/rs.3.rs-7678845/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-22T00:59:21+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-14T14:46:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-14T09:28:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"42693936293283462202479346153482881590","date":"2025-10-14T09:18:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"145151966955221345128845793581675661596","date":"2025-10-14T02:09:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277991539860498293710348837549383661881","date":"2025-10-13T12:41:26+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-12T16:43:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-07T13:08:33+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-03T13:09:29+00:00","index":"","fulltext":""},{"type":"submitted","content":"Obesity Surgery","date":"2025-09-22T10:46:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"obesity-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"obsu","sideBox":"Learn more about [Obesity Surgery](https://link.springer.com/journal/11695)","snPcode":"11695","submissionUrl":"https://submission.springernature.com/new-submission/11695/3","title":"Obesity Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e8788d5b-a349-48a0-9024-f4b569945df6","owner":[],"postedDate":"October 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-09T16:04:21+00:00","versionOfRecord":{"articleIdentity":"rs-7678845","link":"https://doi.org/10.1007/s11695-026-08554-z","journal":{"identity":"obesity-surgery","isVorOnly":false,"title":"Obesity Surgery"},"publishedOn":"2026-03-04 16:00:05","publishedOnDateReadable":"March 4th, 2026"},"versionCreatedAt":"2025-10-27 14:26:57","video":"","vorDoi":"10.1007/s11695-026-08554-z","vorDoiUrl":"https://doi.org/10.1007/s11695-026-08554-z","workflowStages":[]},"version":"v1","identity":"rs-7678845","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7678845","identity":"rs-7678845","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}