Study on anaesthetic agent propofol and sevoflurane as maintenance agent along with anti-emetic drug ondansetron in reducing post operative nausea and vomiting in high-risk patients

Study on anaesthetic agent propofol and sevoflurane as maintenance agent along with anti-emetic drug ondansetron in reducing post operative nausea and vomiting in high-risk patients | 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 Study on anaesthetic agent propofol and sevoflurane as maintenance agent along with anti-emetic drug ondansetron in reducing post operative nausea and vomiting in high-risk patients Lakshmi Sunil, Geetha Acharya This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9261874/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 12 You are reading this latest preprint version Abstract Background: Postoperative nausea and vomiting (PONV) remain among the most common and distressing complications following general anaesthesia, significantly affecting patient satisfaction, recovery times, and healthcare costs. Although ondansetron at a dose of 4 mg IV has long been considered the gold standard for PONV prophylaxis, emerging literature suggests that higher doses may improve efficacy in select high-risk populations. However, the relationship between ondansetron dose, anaesthetic regimen, and PONV incidence remains poorly defined, particularly when using a combination of propofol induction and sevoflurane maintenance. Objective: This prospective observational study aimed to evaluate the incidence of early PONV (within the first two postoperative hours) following pre-induction administration of ondansetron 4 mg in patients receiving propofol–sevoflurane anaesthesia and to assess the influence of demographic and perioperative factors on emesis incidence. Methods: 150 high-risk adult patients aged 18–60 years undergoing elective surgery under general anaesthesia were enrolled. All received ondansetron 4 mg IV during premedication, propofol for induction, and sevoflurane for maintenance. Episodes of nausea and vomiting were recorded at 30, 60, 90, and 120 minutes postoperatively. Statistical analyses included Mann–Whitney U tests for continuous variables and Fisher’s exact tests for categorical data, with significance set at p < 0.05. Results: A total of 150 patients were included in the analysis. The mean age of the cohort was 39.9 ± 13.1 years, with a predominance of female patients (63.3%). The overall incidence of early postoperative nausea and vomiting (within 120 minutes) was 9.3% (14/150). Most episodes were mild in severity, with only a small proportion of patients experiencing repeated vomiting. No statistically significant associations were identified between PONV and demographic variables such as age, sex, body mass index, smoking status, or prior history of PONV (p > 0.05). However, a higher proportion of PONV was observed among patients undergoing otorhinolaryngological procedures, although this did not reach statistical significance when analysed across all surgical departments. Conclusion: Ondansetron 4 mg IV administered pre-medication, combined with propofol induction and sevoflurane maintenance, effectively reduced early PONV incidence to 9.3% among high-risk adults. A higher incidence of PONV was observed in patients undergoing ENT procedures. These findings support the continued use of 4 mg as a sufficient and safe prophylactic dose for early postoperative periods, while underscoring the need for larger comparative studies evaluating dose-response relationships and late PONV outcomes. Ondansetron PONV propofol sevoflurane anaesthesia dose response postoperative nausea antiemetic prophylaxis Introduction Postoperative nausea and vomiting (PONV) are among the most common adverse effects of anaesthesia, with a reported incidence of 20% to 30% in the general surgical population and up to 80% in high-risk groups such as females, nonsmokers, and those with a history of motion sickness or prior PONV [ 1 , 2 , 3 ]. Although not life-threatening, PONV causes considerable discomfort, delays discharge, increases unplanned admissions, and decreases overall patient satisfaction with anaesthesia [ 3 ]. Uncontrolled PONV can lead to wound dehiscence, aspiration pneumonia, electrolyte disturbances, dehydration, and significantly increased healthcare costs [ 4 ]. In ambulatory settings, PONV can compromise fast-track recovery goals and increase economic burdens through extended postoperative care and medication use [ 5 , 6 ]. The multifactorial aetiology of PONV involves an interplay among patient characteristics, surgical procedures, and anaesthetic techniques [ 6 ]. Serotonin release from enterochromaffin cells during surgery plays a pivotal role in activating vagal afferents via 5-Hydroxytryptamine-3 5-H(T₃) receptors, triggering emetic pathways in the brainstem [ 7 , 8 ]. This understanding led to the development of 5-HT₃ receptor antagonists such as ondansetron, which revolutionised PONV management upon their introduction in the early 1990s [ 9 ]. Ondansetron remains the cornerstone of antiemetic prophylaxis due to its rapid onset, minimal sedation, and favourable side effect profile [ 10 ]. The commonly recommended intravenous dose is 4 mg, a value historically established from early dose-ranging studies [ 11 ]. However, emerging evidence suggests that this standard dose may not be universally optimal. A meta-analysis by Apfel et al. (2020) suggested that higher doses (6–8 mg) could improve PONV prevention in high-risk or obese populations, though at the cost of a marginally increased risk of QT interval prolongation [ 11 ]. Other studies have found no significant difference between 4 mg and higher doses, raising questions about whether the “one-size-fits-all” strategy remains justified in modern anaesthesia [ 12 , 13 ]. At the same time, the anaesthetic regimen itself significantly influences PONV risk [ 13 ]. Propofol, widely used for induction and maintenance, possesses intrinsic antiemetic properties. Several randomised trials have demonstrated that total intravenous anaesthesia (TIVA) with propofol reduces PONV incidence compared with volatile anaesthetics like sevoflurane or desflurane [ 14 ]. However, in practical clinical settings, many anaesthesiologists use propofol for induction followed by sevoflurane for maintenance to balance hemodynamic stability, cost, and recovery profile. This combination’s interaction with ondansetron efficacy remains underexplored, especially in diverse, high-risk populations [ 15 ]. Previous literature predominantly focused on homogenous populations—often female laparoscopic patients-limiting generalizability [ 16 , 17 ]. Moreover, most studies examined 24-hour PONV incidence rather than early postoperative outcomes, despite evidence suggesting that nearly half of PONV events occur within the first two hours [ 18 , 19 , 20 ]. Early prophylaxis is critical, as untreated emesis during recovery can lead to aspiration, wound dehiscence, or increased intracranial pressure in neurosurgical cases. Limited real-world data are evaluating the effectiveness of standard-dose (4 mg) ondansetron in preventing early PONV when combined with propofol induction and sevoflurane maintenance, particularly in high-risk mixed-gender populations. Understanding whether this regimen provides sufficient early protection—or whether higher doses or combination therapy are warranted—could directly inform anaesthesia protocols and improve patient outcomes. The present prospective observational study was designed to address this gap by evaluating early (0–120 min) PONV incidence following administration of ondansetron 4 mg IV in high-risk adult patients receiving propofol–sevoflurane anaesthesia. Materials and methods Study Design and Setting This was a prospective observational study conducted in the tertiary centre. The study was designed to evaluate the effectiveness of a single standard dose of ondansetron (4 mg IV) for the prevention of early postoperative nausea and vomiting in high-risk adults undergoing surgery under general anaesthesia with propofol induction and sevoflurane maintenance. The study followed the ethical principles of the Declaration of Helsinki (2013) and was approved by the Institutional Ethics Committee [ 21 ]. Written informed consent was obtained from all participants. Participants Adult patients between 18 and 60 years of age, classified as high risk for PONV based on the modified Apfel scoring system, were included. High-risk criteria included female sex, non-smoking status, history of motion sickness or previous PONV, and anticipated use of volatile anaesthetics or opioids. Exclusion criteria included pregnancy, significant hepatic or renal dysfunction, chronic antiemetic therapy, known ondansetron allergy, QT prolongation, and emergency surgeries. Anaesthetic Technique All patients underwent preoperative evaluation, including fasting verification, airway assessment, and baseline vital parameters. Standard intraoperative monitoring (ECG, pulse oximetry, non-invasive blood pressure, end-tidal CO₂, and temperature) was employed. Premedication included glycopyrrolate 0.2 mg and midazolam 1 mg intravenously. Each patient received ondansetron 4 mg IV as prophylaxis five minutes before induction. Anaesthesia induction was achieved with propofol 1–2 mg/kg, followed by neuromuscular blockade using vecuronium or rocuronium as per the anaesthesiologist's preference. Anaesthesia was maintained using sevoflurane (1–2%) in a 50:50 air–oxygen mixture with intermittent opioid supplementation for analgesia. Controlled ventilation was adjusted to maintain normocapnia. At the end of surgery, sevoflurane was discontinued, and residual neuromuscular blockade was reversed with neostigmine and glycopyrrolate. Postoperative Assessment and Data Collection Postoperatively, patients were monitored in the post-anaesthesia care unit (PACU) for two hours. The primary outcome – PONV - was recorded at 30, 60, 90, and 120 minutes after extubating the patient. Emesis events (including nausea, retching, or vomiting) were recorded by trained nursing staff using a standardised emesis score (0 = none, 1 = nausea, 2 = vomiting once, 3 = recurrent vomiting) [ 18 ]. For analysis, any emesis score > 0 during the 120 minutes was classified accordingly. Demographic and perioperative data, including age, sex, BMI, type and duration of surgery, smoking history, previous PONV history, and intraoperative drugs, were recorded. Statistical Analysis Data were analysed using Python (v3.11; pandas, scipy). Descriptive statistics summarised continuous variables as mean ± SD or median (IQR) and categorical variables as frequencies (%). The Mann–Whitney U test compared continuous variables between patients with and without PONV, given the small event count and non-normal distribution. Fisher’s exact test or chi-square test was used for categorical comparisons. Significance was defined as p < 0.05. Results Demographic Characteristics 150 patients were included in the final analysis after excluding incomplete records. The cohort consisted of 95 females (63.3%) and 55 males (36.7%), with a mean age of 39.9 ± 13.1 years (range 18–60 years). The mean BMI was 24.2 ± 4.4 kg/m². A total of 53 patients (35.3%)were smokers, while only 9 (6.0%)had a history of PONV, as shown in Table 1 . All patients received ondansetron 4 mg IV pre-induction, and anaesthesia was induced with propofol followed by sevoflurane maintenance. Rescue antiemetics and patient satisfaction scores (1–5 scale) were also noted. Table 1 Baseline Demographic and Clinical Characteristics (N = 150) Variable Mean ± SD or n (%) Age (years) 39.9 ± 13.1 Sex Female: 95 (63.3%) Male: 55 (36.7%) BMI (kg/m²) 24.2 ± 4.4 History of PONV Yes: 9 (6.0%) No: 141 (94.0%) Smoking History Yes: 53 (35.3%) No: 97 (64.7%) Ondansetron Dose 4 mg (100%) Incidence of Early PONV Only fourteen patients (9.3%) experienced nausea or vomiting within the first 120 minutes postoperatively, as shown in Table 2 . No significant hemodynamic instability or adverse events related to ondansetron administration were reported. Table 2 Incidence and Severity of Early PONV within 120 minutes post operatively PONV Score Description n % 0 No nausea/vomiting 136 90.7% 1 Nausea only 6 4.0% 2 Nausea + vomiting 5 3.3% ≥ 3 Repeated vomiting 3 2.0% Table 3 High risk factors of PONV within 120 minutes post operatively Variable No PONV PONV Test Used p-value Age (years, median [IQR]) 38 [30–48] 46 [35–55] Mann–Whitney U 0.11 BMI (kg/m², median [IQR]) 24.1 [21.5–27.0] 24.6 [22.0–27.5] Mann–Whitney U 0.81 Female sex (%) 85 (62.5%) 11 (78.6%) Fisher’s exact 0.29 History of PONV (%) 8 (5.9%) 1 (7.1%) Fisher’s exact 1.00 Smoking (%) 48 (35.3%) 5 (35.7%) Fisher’s exact 1.00 Median age was higher among those who developed PONV (46 years) than those who did not (38 years), though this difference was not statistically significant ( p = 0.11). There were no significant associations between PONV and BMI ( p = 0.81), sex ( p = 0.29), smoking (p = 1.00) or history of prior PONV ( p = 1.000), as shown in Table 3 . Overall, while certain trends such as female predominance were noted, none of the evaluated factors emerged as significant predictors in this study. Department-wise Analysis While department-wise comparison did not reach statistical significance, likely due to unequal group sizes and limited event rates, revealed a significantly higher incidence of PONV in ENT procedures (16.7%) (As shown in Table 4 ). Table 4 Department-wise Distribution of PONV Department Total (n) No PONV (n, %) PONV (n, %) ENT 42 35 (83.3%) 7 (16.7%) General Surgery 38 35 (92.1%) 3 (7.9%) Gynaecology 30 28 (93.3%) 2 (6.7%) Orthopaedics 25 23 (92.0%) 2 (8.0%) Others 15 15 (100%) 0 (0%) Total 150 136 (90.7%) 14 (9.3%) Rescue Antiemetic Use and Patient Satisfaction Rescue antiemetics were required in 8 of the 14 patients who experienced PONV. The overall mean satisfaction score was 4.7 ± 0.4 (see Table 5 ), indicating high postoperative comfort. No significant correlation was found between satisfaction score and age, sex, or BMI. Table 5 Patient Satisfaction Scores Parameter Value Patient Satisfaction Score (1–5) 4.7 ± 0.4 Satisfaction Distribution Very satisfied (5): 118 (78.7%) Satisfied (4): 27 (18.0%) Neutral (3): 5 (3.3%) Dissatisfied (1–2): 0 (0%) Discussion Postoperative nausea and vomiting remain a persistent challenge in anaesthesia despite advances in pharmacology and monitoring. The current study contributes valuable real-world data supporting the adequacy of the standard ondansetron 4 mg dose when combined with propofol induction and sevoflurane maintenance in high-risk adults. Clinical Significance of the 4 mg Dose Ondansetron at 4 mg IV remains the globally accepted standard for PONV prophylaxis, offering a balance between efficacy, safety, and cost-effectiveness. Its pharmacokinetic profile provides a therapeutic plasma concentration for 4–6 hours, corresponding well with the early postoperative phase when emesis risk peaks. [ 19 ] The very low incidence of early PONV (9.3%) in this study confirms that the 4 mg dose remains clinically sufficient, particularly when paired with propofol’s intrinsic antiemetic effects. In contrast, several studies have questioned whether higher doses might offer additional benefit. A 2021 randomised controlled trial by Akhavan et al. found no significant reduction in PONV incidence between 4 mg and 8 mg doses but reported a higher frequency of mild headache and QTc prolongation in the 8 mg group. [ 23 ] Similarly, a meta-analysis by Zhang et al. (2023) showed that while 8 mg may slightly reduce late-onset (6–24 h) PONV, the improvement was not clinically meaningful in low- to moderate-risk groups. [ 24 ] Thus, escalating the ondansetron dose beyond 4 mg may not yield proportional benefit and could increase cost and safety concerns. Anaesthetic Technique and its Influence on PONV Anaesthetic technique plays a pivotal role in modulating PONV risk. Propofol, used for induction in all patients, is known to reduce PONV incidence through its action on GABAergic and serotonergic pathways. [ 25 ] Sevoflurane, while generally considered emetogenic, was used at low dial concentrations (1–2%), minimising its potential to trigger nausea. The synergistic effect of low-dose sevoflurane and propofol may therefore explain the extremely low PONV incidence in this cohort. Our findings align with a 2019 clinical report by Uchinami et al., who found no significant difference in PONV incidence when low-concentration sevoflurane was combined with propofol compared to propofol-only anaesthesia [ 26 ]. Likewise, Bansal et al. (2022) reported that propofol–sevoflurane combinations achieved comparable outcomes to total intravenous anaesthesia in female laparoscopic patients when paired with 5-HT₃ antagonists [ 15 ]. Comparative Analysis with Prior Studies The observed 9.3% incidence is substantially lower than that reported in prior literature, where early postoperative PONV rates of 10–30% are common despite prophylaxis [ 15 ]. The difference may be attributed to the uniform administration of ondansetron before induction and the dual anaesthetic strategy used. Importantly, this study highlights that even among high-risk patients, a standardised 4 mg ondansetron dose can provide reliable early prophylaxis when anaesthetic regimens are carefully optimised. Mechanistic Insights The pharmacodynamic ceiling effect of ondansetron may explain the observed dose sufficiency. Beyond 4 mg, receptor saturation at the chemoreceptor trigger zone results in minimal incremental antiemetic benefit [ 27 ]. Additionally, propofol’s modulation of subcortical pathways, including dopaminergic inhibition, further enhances antiemetic synergy [ 28 ]. The combination effectively suppresses both central and peripheral emetic triggers, explaining the observed efficacy. Additional Insights A particularly noteworthy finding was the higher occurrence of PONV among patients undergoing ENT procedures. Even without formal subgroup stratification, this trend was clearly evident and carries significant clinical relevance. The increased susceptibility in this group can be attributed to factors such as vestibular stimulation during middle ear manipulation, pharyngeal irritation, and blood ingestion, all of which are known to activate emetic pathways [ 29 ]. These findings suggest that while ondansetron monotherapy is effective in reducing the overall burden of PONV, it may not be sufficient for certain high-risk surgical populations. In particular, patients undergoing ENT procedures may benefit from a more tailored or multimodal antiemetic approach to further minimise postoperative discomfort. Implications for Practice These findings reinforce that the standard ondansetron 4 mg dose remains adequate for early postoperative prophylaxis, even in high-risk individuals. This has practical implications for anaesthesia providers globally, particularly in resource-limited settings were escalating doses or combining multiple antiemetics increases cost without proportionate benefit. Moreover, the low event rate reduces the need for polypharmacy, aligning with enhanced recovery after surgery (ERAS) principles emphasising streamlined, evidence-based interventions. Overall, this study reinforces the importance of risk stratification in PONV prevention, highlighting that even within a generally low-incidence cohort, specific subgroups continue to demonstrate increased vulnerability Limitations The study’s limitations include its single-centre design and short (120-minute) observation period. Late PONV, which may occur up to 24 hours postoperatively, was not evaluated. Additionally, as all patients received the same ondansetron dose, a true dose–response analysis could not be performed. Future multicentre randomised controlled trials comparing 4 mg versus 8 mg ondansetron under similar anaesthetic conditions would provide more definitive evidence. Furthermore, while a higher occurrence of PONV was observed in patients undergoing ENT procedures, detailed subgroup analysis was limited and requires further validation in larger studies. Conclusion In this prospective observational study, ondansetron 4 mg IV administered before induction effectively prevented early postoperative nausea and vomiting in high-risk adults undergoing general anaesthesia with propofol induction and sevoflurane maintenance. The observed incidence of only 9.3% supports the adequacy of the standard dose for early PONV prophylaxis. The combination of a propofol-based induction with low-dose sevoflurane maintenance may provide additive protection against PONV. Given its safety, cost-effectiveness, and consistent clinical performance, ondansetron 4 mg remains the optimal choice for early postoperative prophylaxis in high-risk patients. However, future studies comparing dose escalation, combination regimens, and late PONV outcomes are warranted to refine antiemetic protocols for diverse patient populations. Also, ondansetron helped reduce PONV overall, but patients undergoing ENT procedures appeared more prone to it, indicating a need for more focused preventive approaches in this group. Abbreviations PONV Post Operative Nausea and Vomiting ENT Ear, Nose, and Throat BMI Body Mass Index IV intravenous IQR Interquartile Range Declarations Ethics approval and consent to participate: This study was approved by the Institutional Ethics Committee of ( no. SIU/IEC/616) [Symbiosis Medical college for women, Symbiosis International ( Deemed University ), Pune]. Written informed consent was obtained from all participants. Consent for publication: Not Applicable Availability of data and materials: The datasets generated and analysed during the current study are not publicly available due to patient confidentiality but are available from the corresponding author on reasonable request, subject to appropriate ethical approval. Competing Interests: The authors declare that they have no competing interests. Funding- non funding: No funding was received for this study. Authors' contributions: Lakshmi Sunil conducted data collection, performed statistical analysis, and drafted the manuscript. Dr Geetha Acharya provided academic guidance, contributed to the study design, and assisted in the selection and refinement of the manuscript title. All authors reviewed and approved the final version of the manuscript. Acknowledgements: We would like to express our heartfelt gratitude to everyone who supported us throughout this study. This work would not have been possible without the dedication and cooperation of our patients and their families, who trusted us and generously allowed their experiences to become part of this research. We are deeply thankful to our mentors, colleagues, and the entire Department of Anaesthesiology for their constant encouragement, thoughtful guidance, and steady presence at every stage of this project. Their willingness to share time, expertise, and honest feedback helped shape this work into its final form. Our sincere appreciation also goes to the clinical and technical teams who assisted with data collection, imaging, and statistical analysis. Finally, we extend our warm thanks to everyone, both within and outside the hospital, who offered support, motivation, or a listening ear along the way. Each contribution, big or small, played a meaningful role in bringing this study to completion. References Gan TJ. Risk factors for postoperative nausea and vomiting. Anesth Analg. 2006;102(6):1884–1898. Apfel CC, Läärä E, Koivuranta M, Greim CA, Roewer N. A simplified risk score for predicting postoperative nausea and vomiting. Anesthesiology . 1999;91(3):693–700. 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Supplementary Files APPENDI1.docx Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 12 May, 2026 Reviews received at journal 12 May, 2026 Reviewers agreed at journal 11 May, 2026 Reviewers agreed at journal 28 Apr, 2026 Reviews received at journal 27 Apr, 2026 Reviewers agreed at journal 27 Apr, 2026 Reviewers agreed at journal 27 Apr, 2026 Reviewers invited by journal 17 Apr, 2026 Editor assigned by journal 17 Apr, 2026 Editor invited by journal 09 Apr, 2026 Submission checks completed at journal 09 Apr, 2026 First submitted to journal 09 Apr, 2026 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-9261874","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":627931173,"identity":"12853289-a6b0-40e4-9c20-cb9b8ac66d5b","order_by":0,"name":"Lakshmi Sunil","email":"","orcid":"","institution":"MBBS, Symbiosis medical college for women, Symbiosis International (Deemed University)","correspondingAuthor":false,"prefix":"","firstName":"Lakshmi","middleName":"","lastName":"Sunil","suffix":""},{"id":627931174,"identity":"8844f15f-0914-409b-b834-efa89420b83f","order_by":1,"name":"Geetha Acharya","email":"data:image/png;base64,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","orcid":"","institution":"Symbiosis International (Deemed University)","correspondingAuthor":true,"prefix":"","firstName":"Geetha","middleName":"","lastName":"Acharya","suffix":""}],"badges":[],"createdAt":"2026-03-30 02:54:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9261874/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9261874/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108006631,"identity":"b70b1385-5b91-416d-ac5d-bdbebdfb6181","added_by":"auto","created_at":"2026-04-28 12:56:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":277455,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9261874/v1/82f70f8f-d3f3-4404-bd5a-01638ad0472a.pdf"},{"id":107904114,"identity":"1520d646-2c1f-4246-91a4-d9308b9868ca","added_by":"auto","created_at":"2026-04-27 12:19:44","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":19413,"visible":true,"origin":"","legend":"","description":"","filename":"APPENDI1.docx","url":"https://assets-eu.researchsquare.com/files/rs-9261874/v1/4c6e9d6ecfd4cbd05722baf9.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Study on anaesthetic agent propofol and sevoflurane as maintenance agent along with anti-emetic drug ondansetron in reducing post operative nausea and vomiting in high-risk patients","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePostoperative nausea and vomiting (PONV) are among the most common adverse effects of anaesthesia, with a reported incidence of 20% to 30% in the general surgical population and up to 80% in high-risk groups such as females, nonsmokers, and those with a history of motion sickness or prior PONV [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Although not life-threatening, PONV causes considerable discomfort, delays discharge, increases unplanned admissions, and decreases overall patient satisfaction with anaesthesia [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Uncontrolled PONV can lead to wound dehiscence, aspiration pneumonia, electrolyte disturbances, dehydration, and significantly increased healthcare costs [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In ambulatory settings, PONV can compromise fast-track recovery goals and increase economic burdens through extended postoperative care and medication use [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe multifactorial aetiology of PONV involves an interplay among patient characteristics, surgical procedures, and anaesthetic techniques [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Serotonin release from enterochromaffin cells during surgery plays a pivotal role in activating vagal afferents via 5-Hydroxytryptamine-3 5-H(T₃) receptors, triggering emetic pathways in the brainstem [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This understanding led to the development of 5-HT₃ receptor antagonists such as ondansetron, which revolutionised PONV management upon their introduction in the early 1990s [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOndansetron remains the cornerstone of antiemetic prophylaxis due to its rapid onset, minimal sedation, and favourable side effect profile [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The commonly recommended intravenous dose is 4 mg, a value historically established from early dose-ranging studies [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. However, emerging evidence suggests that this standard dose may not be universally optimal. A meta-analysis by Apfel et al. (2020) suggested that higher doses (6\u0026ndash;8 mg) could improve PONV prevention in high-risk or obese populations, though at the cost of a marginally increased risk of QT interval prolongation [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Other studies have found no significant difference between 4 mg and higher doses, raising questions about whether the \u0026ldquo;one-size-fits-all\u0026rdquo; strategy remains justified in modern anaesthesia [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAt the same time, the anaesthetic regimen itself significantly influences PONV risk [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Propofol, widely used for induction and maintenance, possesses intrinsic antiemetic properties. Several randomised trials have demonstrated that total intravenous anaesthesia (TIVA) with propofol reduces PONV incidence compared with volatile anaesthetics like sevoflurane or desflurane [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, in practical clinical settings, many anaesthesiologists use propofol for induction followed by sevoflurane for maintenance to balance hemodynamic stability, cost, and recovery profile. This combination\u0026rsquo;s interaction with ondansetron efficacy remains underexplored, especially in diverse, high-risk populations [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePrevious literature predominantly focused on homogenous populations\u0026mdash;often female laparoscopic patients-limiting generalizability [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Moreover, most studies examined 24-hour PONV incidence rather than early postoperative outcomes, despite evidence suggesting that nearly half of PONV events occur within the first two hours [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Early prophylaxis is critical, as untreated emesis during recovery can lead to aspiration, wound dehiscence, or increased intracranial pressure in neurosurgical cases.\u003c/p\u003e \u003cp\u003eLimited real-world data are evaluating the effectiveness of standard-dose (4 mg) ondansetron in preventing early PONV when combined with propofol induction and sevoflurane maintenance, particularly in high-risk mixed-gender populations. Understanding whether this regimen provides sufficient early protection\u0026mdash;or whether higher doses or combination therapy are warranted\u0026mdash;could directly inform anaesthesia protocols and improve patient outcomes.\u003c/p\u003e \u003cp\u003eThe present prospective observational study was designed to address this gap by evaluating early (0\u0026ndash;120 min) PONV incidence following administration of ondansetron 4 mg IV in high-risk adult patients receiving propofol\u0026ndash;sevoflurane anaesthesia.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Setting\u003c/h2\u003e \u003cp\u003eThis was a prospective observational study conducted in the tertiary centre. The study was designed to evaluate the effectiveness of a single standard dose of ondansetron (4 mg IV) for the prevention of early postoperative nausea and vomiting in high-risk adults undergoing surgery under general anaesthesia with propofol induction and sevoflurane maintenance. The study followed the ethical principles of the Declaration of Helsinki (2013) and was approved by the Institutional Ethics Committee [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Written informed consent was obtained from all participants.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eParticipants\u003c/h3\u003e\n\u003cp\u003eAdult patients between 18 and 60 years of age, classified as high risk for PONV based on the modified Apfel scoring system, were included. High-risk criteria included female sex, non-smoking status, history of motion sickness or previous PONV, and anticipated use of volatile anaesthetics or opioids. Exclusion criteria included pregnancy, significant hepatic or renal dysfunction, chronic antiemetic therapy, known ondansetron allergy, QT prolongation, and emergency surgeries.\u003c/p\u003e\n\u003ch3\u003eAnaesthetic Technique\u003c/h3\u003e\n\u003cp\u003eAll patients underwent preoperative evaluation, including fasting verification, airway assessment, and baseline vital parameters. Standard intraoperative monitoring (ECG, pulse oximetry, non-invasive blood pressure, end-tidal CO₂, and temperature) was employed. Premedication included glycopyrrolate 0.2 mg and midazolam 1 mg intravenously.\u003c/p\u003e \u003cp\u003eEach patient received ondansetron 4 mg IV as prophylaxis five minutes before induction. Anaesthesia induction was achieved with propofol 1\u0026ndash;2 mg/kg, followed by neuromuscular blockade using vecuronium or rocuronium as per the anaesthesiologist's preference. Anaesthesia was maintained using sevoflurane (1\u0026ndash;2%) in a 50:50 air\u0026ndash;oxygen mixture with intermittent opioid supplementation for analgesia. Controlled ventilation was adjusted to maintain normocapnia. At the end of surgery, sevoflurane was discontinued, and residual neuromuscular blockade was reversed with neostigmine and glycopyrrolate.\u003c/p\u003e\n\u003ch3\u003ePostoperative Assessment and Data Collection\u003c/h3\u003e\n\u003cp\u003ePostoperatively, patients were monitored in the post-anaesthesia care unit (PACU) for two hours. The primary outcome \u0026ndash; PONV - was recorded at 30, 60, 90, and 120 minutes after extubating the patient. Emesis events (including nausea, retching, or vomiting) were recorded by trained nursing staff using a standardised emesis score (0\u0026thinsp;=\u0026thinsp;none, 1\u0026thinsp;=\u0026thinsp;nausea, 2\u0026thinsp;=\u0026thinsp;vomiting once, 3\u0026thinsp;=\u0026thinsp;recurrent vomiting) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. For analysis, any emesis score\u0026thinsp;\u0026gt;\u0026thinsp;0 during the 120 minutes was classified accordingly.\u003c/p\u003e \u003cp\u003eDemographic and perioperative data, including age, sex, BMI, type and duration of surgery, smoking history, previous PONV history, and intraoperative drugs, were recorded.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eData were analysed using Python (v3.11; pandas, scipy). Descriptive statistics summarised continuous variables as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or median (IQR) and categorical variables as frequencies (%). The Mann\u0026ndash;Whitney U test compared continuous variables between patients with and without PONV, given the small event count and non-normal distribution. Fisher\u0026rsquo;s exact test or chi-square test was used for categorical comparisons. Significance was defined as \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eDemographic Characteristics\u003c/h2\u003e \u003cp\u003e150 patients were included in the final analysis after excluding incomplete records. The cohort consisted of 95 females (63.3%) and 55 males (36.7%), with a mean age of 39.9\u0026thinsp;\u0026plusmn;\u0026thinsp;13.1 years (range 18\u0026ndash;60 years). The mean BMI was 24.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4 kg/m\u0026sup2;. A total of 53 patients (35.3%)were smokers, while only 9 (6.0%)had a history of PONV, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. All patients received ondansetron 4 mg IV pre-induction, and anaesthesia was induced with propofol followed by sevoflurane maintenance. Rescue antiemetics and patient satisfaction scores (1\u0026ndash;5 scale) were also noted.\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\u003eBaseline Demographic and Clinical Characteristics (N\u0026thinsp;=\u0026thinsp;150)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \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\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or n (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39.9\u0026thinsp;\u0026plusmn;\u0026thinsp;13.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale: 95 (63.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale: 55 (36.7%)\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\u003e24.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of PONV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes: 9 (6.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo: 141 (94.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking History\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes: 53 (35.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo: 97 (64.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOndansetron Dose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 mg (100%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eIncidence of Early PONV\u003c/h3\u003e\n\u003cp\u003eOnly fourteen patients (9.3%) experienced nausea or vomiting within the first 120 minutes postoperatively, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. No significant hemodynamic instability or adverse events related to ondansetron administration were reported.\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\u003eIncidence and Severity of Early PONV within 120 minutes post operatively\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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=\"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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePONV Score\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDescription\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e0\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo nausea/vomiting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e136\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e90.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNausea only\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNausea\u0026thinsp;+\u0026thinsp;vomiting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e\u0026ge;\u0026thinsp;3\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRepeated vomiting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eHigh risk factors of PONV within 120 minutes post operatively\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=\"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=\"left\" 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\u003eNo PONV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePONV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTest Used\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years, median [IQR])\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38 [30\u0026ndash;48]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46 [35\u0026ndash;55]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMann\u0026ndash;Whitney U\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u0026sup2;, median [IQR])\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.1 [21.5\u0026ndash;27.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.6 [22.0\u0026ndash;27.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMann\u0026ndash;Whitney U\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale sex (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e85 (62.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (78.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFisher\u0026rsquo;s exact\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of PONV (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (7.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFisher\u0026rsquo;s exact\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48 (35.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (35.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFisher\u0026rsquo;s exact\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eMedian age was higher among those who developed PONV (46 years) than those who did not (38 years), though this difference was not statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.11). There were no significant associations between PONV and BMI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.81), sex (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.29), smoking (p\u0026thinsp;=\u0026thinsp;1.00) or history of prior PONV (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.000), as shown in Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Overall, while certain trends such as female predominance were noted, none of the evaluated factors emerged as significant predictors in this study.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eDepartment-wise Analysis\u003c/h2\u003e \u003cp\u003eWhile department-wise comparison did not reach statistical significance, likely due to unequal group sizes and limited event rates, revealed a significantly higher incidence of PONV in ENT procedures (16.7%) (As shown in Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDepartment-wise Distribution of PONV\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDepartment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal (n)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo PONV (n, %)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePONV (n, %)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eENT\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35 (83.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (16.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGeneral Surgery\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35 (92.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (7.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGynaecology\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28 (93.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (6.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOrthopaedics\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (92.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (8.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOthers\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e136 (90.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14 (9.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eRescue Antiemetic Use and Patient Satisfaction\u003c/h2\u003e \u003cp\u003eRescue antiemetics were required in 8 of the 14 patients who experienced PONV. The overall mean satisfaction score was 4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 (see Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), indicating high postoperative comfort. No significant correlation was found between satisfaction score and age, sex, or BMI.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePatient Satisfaction Scores\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatient Satisfaction Score (1\u0026ndash;5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSatisfaction Distribution\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVery satisfied (5): 118 (78.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSatisfied (4): 27 (18.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNeutral (3): 5 (3.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDissatisfied (1\u0026ndash;2): 0 (0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003ePostoperative nausea and vomiting remain a persistent challenge in anaesthesia despite advances in pharmacology and monitoring. The current study contributes valuable real-world data supporting the adequacy of the standard ondansetron 4 mg dose when combined with propofol induction and sevoflurane maintenance in high-risk adults.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eClinical Significance of the 4 mg Dose\u003c/h2\u003e \u003cp\u003eOndansetron at 4 mg IV remains the globally accepted standard for PONV prophylaxis, offering a balance between efficacy, safety, and cost-effectiveness. Its pharmacokinetic profile provides a therapeutic plasma concentration for 4\u0026ndash;6 hours, corresponding well with the early postoperative phase when emesis risk peaks. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] The very low incidence of early PONV (9.3%) in this study confirms that the 4 mg dose remains clinically sufficient, particularly when paired with propofol\u0026rsquo;s intrinsic antiemetic effects.\u003c/p\u003e \u003cp\u003eIn contrast, several studies have questioned whether higher doses might offer additional benefit. A 2021 randomised controlled trial by Akhavan et al. found no significant reduction in PONV incidence between 4 mg and 8 mg doses but reported a higher frequency of mild headache and QTc prolongation in the 8 mg group. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] Similarly, a meta-analysis by Zhang et al. (2023) showed that while 8 mg may slightly reduce late-onset (6\u0026ndash;24 h) PONV, the improvement was not clinically meaningful in low- to moderate-risk groups. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] Thus, escalating the ondansetron dose beyond 4 mg may not yield proportional benefit and could increase cost and safety concerns.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eAnaesthetic Technique and its Influence on PONV\u003c/h2\u003e \u003cp\u003eAnaesthetic technique plays a pivotal role in modulating PONV risk. Propofol, used for induction in all patients, is known to reduce PONV incidence through its action on GABAergic and serotonergic pathways. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] Sevoflurane, while generally considered emetogenic, was used at low dial concentrations (1\u0026ndash;2%), minimising its potential to trigger nausea. The synergistic effect of low-dose sevoflurane and propofol may therefore explain the extremely low PONV incidence in this cohort.\u003c/p\u003e \u003cp\u003eOur findings align with a 2019 clinical report by Uchinami et al., who found no significant difference in PONV incidence when low-concentration sevoflurane was combined with propofol compared to propofol-only anaesthesia [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Likewise, Bansal et al. (2022) reported that propofol\u0026ndash;sevoflurane combinations achieved comparable outcomes to total intravenous anaesthesia in female laparoscopic patients when paired with 5-HT₃ antagonists [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eComparative Analysis with Prior Studies\u003c/h2\u003e \u003cp\u003eThe observed 9.3% incidence is substantially lower than that reported in prior literature, where early postoperative PONV rates of 10\u0026ndash;30% are common despite prophylaxis [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The difference may be attributed to the uniform administration of ondansetron before induction and the dual anaesthetic strategy used. Importantly, this study highlights that even among high-risk patients, a standardised 4 mg ondansetron dose can provide reliable early prophylaxis when anaesthetic regimens are carefully optimised.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eMechanistic Insights\u003c/h2\u003e \u003cp\u003eThe pharmacodynamic ceiling effect of ondansetron may explain the observed dose sufficiency. Beyond 4 mg, receptor saturation at the chemoreceptor trigger zone results in minimal incremental antiemetic benefit [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Additionally, propofol\u0026rsquo;s modulation of subcortical pathways, including dopaminergic inhibition, further enhances antiemetic synergy [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The combination effectively suppresses both central and peripheral emetic triggers, explaining the observed efficacy.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eAdditional Insights\u003c/h2\u003e \u003cp\u003eA particularly noteworthy finding was the higher occurrence of PONV among patients undergoing ENT procedures. Even without formal subgroup stratification, this trend was clearly evident and carries significant clinical relevance. The increased susceptibility in this group can be attributed to factors such as vestibular stimulation during middle ear manipulation, pharyngeal irritation, and blood ingestion, all of which are known to activate emetic pathways [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThese findings suggest that while ondansetron monotherapy is effective in reducing the overall burden of PONV, it may not be sufficient for certain high-risk surgical populations. In particular, patients undergoing ENT procedures may benefit from a more tailored or multimodal antiemetic approach to further minimise postoperative discomfort.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eImplications for Practice\u003c/h2\u003e \u003cp\u003eThese findings reinforce that the standard ondansetron 4 mg dose remains adequate for early postoperative prophylaxis, even in high-risk individuals. This has practical implications for anaesthesia providers globally, particularly in resource-limited settings were escalating doses or combining multiple antiemetics increases cost without proportionate benefit. Moreover, the low event rate reduces the need for polypharmacy, aligning with enhanced recovery after surgery (ERAS) principles emphasising streamlined, evidence-based interventions.\u003c/p\u003e \u003cp\u003eOverall, this study reinforces the importance of risk stratification in PONV prevention, highlighting that even within a generally low-incidence cohort, specific subgroups continue to demonstrate increased vulnerability\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eThe study\u0026rsquo;s limitations include its single-centre design and short (120-minute) observation period. Late PONV, which may occur up to 24 hours postoperatively, was not evaluated. Additionally, as all patients received the same ondansetron dose, a true dose\u0026ndash;response analysis could not be performed. Future multicentre randomised controlled trials comparing 4 mg versus 8 mg ondansetron under similar anaesthetic conditions would provide more definitive evidence.\u003c/p\u003e \u003cp\u003eFurthermore, while a higher occurrence of PONV was observed in patients undergoing ENT procedures, detailed subgroup analysis was limited and requires further validation in larger studies.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this prospective observational study, ondansetron 4 mg IV administered before induction effectively prevented early postoperative nausea and vomiting in high-risk adults undergoing general anaesthesia with propofol induction and sevoflurane maintenance. The observed incidence of only 9.3% supports the adequacy of the standard dose for early PONV prophylaxis. The combination of a propofol-based induction with low-dose sevoflurane maintenance may provide additive protection against PONV.\u003c/p\u003e \u003cp\u003eGiven its safety, cost-effectiveness, and consistent clinical performance, ondansetron 4 mg remains the optimal choice for early postoperative prophylaxis in high-risk patients. However, future studies comparing dose escalation, combination regimens, and late PONV outcomes are warranted to refine antiemetic protocols for diverse patient populations.\u003c/p\u003e \u003cp\u003eAlso, ondansetron helped reduce PONV overall, but patients undergoing ENT procedures appeared more prone to it, indicating a need for more focused preventive approaches in this group.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePONV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePost Operative Nausea and Vomiting\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eENT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEar, Nose, and Throat\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBMI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBody Mass Index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eintravenous\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIQR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInterquartile Range\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval and consent to participate:\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Ethics Committee of ( no. SIU/IEC/616) [Symbiosis Medical college for women, Symbiosis International \u0026nbsp;( Deemed University ), Pune]. Written informed consent was obtained from all participants.\u003c/p\u003e\n\u003cp\u003eConsent for publication:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNot Applicable\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials:\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analysed during the current study are not publicly available due to patient confidentiality but are available \u0026nbsp;from the corresponding author on reasonable request, subject to appropriate ethical approval.\u003c/p\u003e\n\u003cp\u003eCompeting Interests:\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFunding- non funding:\u003c/p\u003e\n\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; contributions:\u003c/p\u003e\n\u003cp\u003eLakshmi Sunil conducted data collection, performed statistical analysis, and drafted the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDr Geetha Acharya provided academic guidance, contributed to the study design, and assisted in the selection and refinement of the manuscript title. All authors reviewed and approved the final version of the manuscript.\u003cbr\u003e\u0026nbsp;Acknowledgements:\u003c/p\u003e\n\u003cp\u003eWe would like to express our heartfelt gratitude to everyone who supported us throughout this study. This work would not have been possible without the dedication and cooperation of our patients and their families, who trusted us and generously allowed their experiences to become part of this research.\u003c/p\u003e\n\u003cp\u003eWe are deeply thankful to our mentors, colleagues, and the entire Department of Anaesthesiology for their constant encouragement, thoughtful guidance, and steady presence at every stage of this project. Their willingness to share time, expertise, and honest feedback helped shape this work into its final form.\u003c/p\u003e\n\u003cp\u003eOur sincere appreciation also goes to the clinical and technical teams who assisted with data collection, imaging, and statistical analysis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFinally, we extend our warm thanks to everyone, both within and outside the hospital, who offered support, motivation, or a listening ear along the way. Each contribution, big or small, played a meaningful role in bringing this study to completion.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eGan TJ. Risk factors for postoperative nausea and vomiting. \u003cem\u003eAnesth Analg.\u003c/em\u003e 2006;102(6):1884\u0026ndash;1898.\u003c/li\u003e\n \u003cli\u003eApfel CC, L\u0026auml;\u0026auml;r\u0026auml; E, Koivuranta M, Greim CA, Roewer N. A simplified risk score for predicting postoperative nausea and vomiting. \u003cem\u003eAnesthesiology\u003c/em\u003e. 1999;91(3):693\u0026ndash;700.\u003c/li\u003e\n \u003cli\u003eLuo D, Huang Z, Tang S, et al. Risk analysis of postoperative nausea and vomiting in patients after gynecologic laparoscopic surgery. \u003cem\u003eBMC Anaesthesia\u003c/em\u003e. 2024;24(1):345. Published 2024 Sep 28. doi:10.1186/s12871-024-02727-y\u003c/li\u003e\n \u003cli\u003eMyles PS, Williams DL, Hendrata M, Anderson H, Weeks AM. Patient satisfaction after anaesthesia and surgery. \u003cem\u003eBr J Anaesth.\u003c/em\u003e 2000; 84:6\u0026ndash;10.\u003c/li\u003e\n \u003cli\u003eBhakta P, Ghosh BR, Singh U, et al. Incidence of postoperative nausea and vomiting following gynaecological laparoscopy: A comparison of standard anaesthetic technique and propofol infusion. \u003cem\u003eActa Anaesthesiol Taiwan\u003c/em\u003e. 2016;54(4):108-113. doi: 10.1016/j.aat.2016.10.002\u003c/li\u003e\n \u003cli\u003ePierre S, Whelan R. Nausea and vomiting after surgery. \u003cem\u003eContin Educ Anaesth Crit Care Pain.\u003c/em\u003e 2013;13(1):28\u0026ndash;32.\u003c/li\u003e\n \u003cli\u003eMyles PS, Wengritzky R. Simplified postoperative nausea and vomiting impact scale for audit and post-discharge review. British journal of anaesthesia. 2012 Mar 1;108(3):423-9.\u003c/li\u003e\n \u003cli\u003eHorn CC. The physiology of nausea and vomiting. \u003cem\u003eAdv Exp Med Biol.\u003c/em\u003e 2014; 817:15\u0026ndash;30.\u003c/li\u003e\n \u003cli\u003eTang J, Chen X, White PF, Wender RH, Ma H, Sloninsky A, Naruse R, Kariger R, Webb T, Zaentz A. Antiemetic prophylaxis for office-based surgery: are the 5-HT3 receptor antagonists beneficial? Anesthesiology. 2003 Feb 1;98(2):293-8.\u003c/li\u003e\n \u003cli\u003eWang JJ et al. Ondansetron vs. metoclopramide for PONV prophylaxis: a meta-analysis. \u003cem\u003eAnesth Analg.\u003c/em\u003e 2015;120(3):693\u0026ndash;701.\u003c/li\u003e\n \u003cli\u003eApfel CC et al. Dose-response of ondansetron for preventing PONV: an updated meta-analysis. \u003cem\u003eEur J Anaesthesiol.\u003c/em\u003e 2020;37(3):234\u0026ndash;243.\u003c/li\u003e\n \u003cli\u003ePurhonen S, Koski EM, Niskanen M, Hynynen M. Efficacy and costs of 3 anaesthetic regimens in the prevention of postoperative nausea and vomiting. Journal of clinical anesthesia. 2006 Feb 1;18(1):41-5.\u003c/li\u003e\n \u003cli\u003eKovac AL. Prevention and treatment of PONV. \u003cem\u003eDrugs.\u003c/em\u003e 2014;74(13):1525\u0026ndash;1537.\u003c/li\u003e\n \u003cli\u003eKranke P, Eberhart LHJ. Multimodal antiemetic prophylaxis in 2024: what\u0026rsquo;s new? \u003cem\u003eCurr Opin Anaesthesiol.\u003c/em\u003e 2024;37(2):187\u0026ndash;194.\u003c/li\u003e\n \u003cli\u003eBansal T, Singhal S, Kundu K. Propofol and sevoflurane as maintenance agents in PONV. \u003cem\u003eMed Gas Res.\u003c/em\u003e 2022; 12:137\u0026ndash;140.\u003c/li\u003e\n \u003cli\u003eBorgeat A, Wilder-Smith OH, Saiah M, Rifat K. Propofol\u0026rsquo;s antiemetic effects. \u003cem\u003eAnesth Analg.\u003c/em\u003e 1992;74(4):539\u0026ndash;545.\u003c/li\u003e\n \u003cli\u003eZheng XZ, Cheng B, Luo J, Xiong QJ, Min S, Wei K. The characteristics and risk factors of the postoperative nausea and vomiting in female patients undergoing laparoscopic sleeve gastrectomy and laparoscopic gynaecological surgeries: a propensity score matching analysis. European Review for Medical \u0026amp; Pharmacological Sciences. 2021 Jan 1;25(1).\u003c/li\u003e\n \u003cli\u003eApfel CC et al. Simplified risk score for predicting PONV. \u003cem\u003eAnesthesiology.\u003c/em\u003e 1999; 91:693\u0026ndash;700.\u003c/li\u003e\n \u003cli\u003eDas S, Kumar A, Gupta A, Kumar A. A Randomised Controlled Trial to Compare the Effect of Ramosetron and Ondansetron in Prevention of Postoperative Nausea and Vomiting in Patients Undergoing Laparoscopic Gynaecological Procedures. \u003cem\u003eCureus\u003c/em\u003e. 2022;14(9):e29200. Published 2022 Sep 15. doi:10.7759/cureus. 29200\u003c/li\u003e\n \u003cli\u003eEberhart LH et al. Temporal patterns of PONV. \u003cem\u003eBr J Anaesth.\u003c/em\u003e 2017;118(3):369\u0026ndash;377.\u003c/li\u003e\n \u003cli\u003eWorld Medical Association. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. \u003cem\u003eJAMA\u003c/em\u003e. 2013;310(20):2191-2194. doi:10.1001/jama.2013.281053\u003c/li\u003e\n \u003cli\u003eScuderi PE. Pharmacology of antiemetics. \u003cem\u003eAnesth Clin North Am.\u003c/em\u003e 2012;30(3):515\u0026ndash;534.\u003c/li\u003e\n \u003cli\u003eAkhavan O et al. Comparison of 4 mg vs 8 mg ondansetron for PONV prevention: a randomized trial. \u003cem\u003eJ Clin Anesth.\u003c/em\u003e 2021;73:110329.\u003c/li\u003e\n \u003cli\u003eZhang D et al. Efficacy of ondansetron dosing for PONV: systematic review and meta-analysis. \u003cem\u003eBr J Anaesth.\u003c/em\u003e 2023;130(2):189\u0026ndash;199.\u003c/li\u003e\n \u003cli\u003eSneyd JR, Carr A. Propofol and antiemesis. \u003cem\u003eAnesth Analg.\u003c/em\u003e 2020;131(1):107\u0026ndash;116.\u003c/li\u003e\n \u003cli\u003eUchinami Y et al. Combination of low sevoflurane and propofol anesthesia and PONV incidence. \u003cem\u003eJA Clin Rep.\u003c/em\u003e 2019;5:70.\u003c/li\u003e\n \u003cli\u003eYamakage M et al. Pharmacodynamic modeling of ondansetron. \u003cem\u003eJ Pharmacol Sci.\u003c/em\u003e 2018;137(4):401\u0026ndash;409.\u003c/li\u003e\n \u003cli\u003eSkolnik A, Gan TJ. Propofol and other sedatives as antiemetics. In: Gan TJ, Habib AS, eds. \u003cem\u003ePostoperative Nausea and Vomiting: A Practical Guide\u003c/em\u003e. Cambridge University Press; 2016:90-97\u003c/li\u003e\n \u003cli\u003eYosief PK, Beraki G, Mayer S, Mengistu M, Tesfamariam E. Incidence and risk factors of postoperative nausea and vomiting after ENT surgery. Int J Anesthetic Anesthesiol. 2022 Mar 31;9:132.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Ondansetron, PONV, propofol, sevoflurane, anaesthesia, dose response, postoperative nausea, antiemetic prophylaxis","lastPublishedDoi":"10.21203/rs.3.rs-9261874/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9261874/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePostoperative nausea and vomiting (PONV) remain among the most common and distressing complications following general anaesthesia, significantly affecting patient satisfaction, recovery times, and healthcare costs. Although ondansetron at a dose of 4 mg IV has long been considered the gold standard for PONV prophylaxis, emerging literature suggests that higher doses may improve efficacy in select high-risk populations. However, the relationship between ondansetron dose, anaesthetic regimen, and PONV incidence remains poorly defined, particularly when using a combination of propofol induction and sevoflurane maintenance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003e\u003cbr\u003e\nThis prospective observational study aimed to evaluate the incidence of early PONV (within the first two postoperative hours) following pre-induction administration of ondansetron 4 mg in patients receiving propofol–sevoflurane anaesthesia and to assess the influence of demographic and perioperative factors on emesis incidence.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e\u003cbr\u003e\n150 high-risk adult patients aged 18–60 years undergoing elective surgery under general anaesthesia were enrolled. All received ondansetron 4 mg IV during premedication, propofol for induction, and sevoflurane for maintenance. Episodes of nausea and vomiting were recorded at 30, 60, 90, and 120 minutes postoperatively. Statistical analyses included Mann–Whitney U tests for continuous variables and Fisher’s exact tests for categorical data, with significance set at \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e\u003cbr\u003e\nA total of 150 patients were included in the analysis. The mean age of the cohort was 39.9 ± 13.1 years, with a predominance of female patients (63.3%). The overall incidence of early postoperative nausea and vomiting (within 120 minutes) was 9.3% (14/150). Most episodes were mild in severity, with only a small proportion of patients experiencing repeated vomiting.\u003c/p\u003e\n\u003cp\u003eNo statistically significant associations were identified between PONV and demographic variables such as age, sex, body mass index, smoking status, or prior history of PONV (p \u0026gt; 0.05). However, a higher proportion of PONV was observed among patients undergoing otorhinolaryngological procedures, although this did not reach statistical significance when analysed across all surgical departments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e\u003cbr\u003e\nOndansetron 4 mg IV administered pre-medication, combined with propofol induction and sevoflurane maintenance, effectively reduced early PONV incidence to 9.3% among high-risk adults. A higher incidence of PONV was observed in patients undergoing ENT procedures. These findings support the continued use of 4 mg as a sufficient and safe prophylactic dose for early postoperative periods, while underscoring the need for larger comparative studies evaluating dose-response relationships and late PONV outcomes.\u003c/p\u003e","manuscriptTitle":"Study on anaesthetic agent propofol and sevoflurane as maintenance agent along with anti-emetic drug ondansetron in reducing post operative nausea and vomiting in high-risk patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-27 12:19:40","doi":"10.21203/rs.3.rs-9261874/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-12T14:50:19+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-12T05:03:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"303113029372947767135334423260027774289","date":"2026-05-12T03:20:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"74066772966324711360045876397481711315","date":"2026-04-28T17:37:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-27T18:18:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"18788770206086543068338883037168042800","date":"2026-04-27T17:37:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"84317252520547902057602592067945418964","date":"2026-04-27T17:04:25+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-17T16:16:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-17T16:12:45+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-09T11:08:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-09T06:26:05+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2026-04-09T06:15:11+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"402c2ca2-4112-478e-bcc8-1a9b3a348312","owner":[],"postedDate":"April 27th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-12T14:50:19+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-12T05:03:44+00:00","index":204,"fulltext":""},{"type":"reviewerAgreed","content":"303113029372947767135334423260027774289","date":"2026-05-12T03:20:26+00:00","index":203,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T14:58:31+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-27 12:19:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9261874","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9261874","identity":"rs-9261874","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}