Instrumental in Surgery: A Narrative Review on Energy-based Surgical Cutting Devices and Surgical Smoke.

No study to date has systematically investigated power settings and electrode configurations and their influence on particulate production. Advanced electrodes that have nonstick coatings may improve cutting performance and reduce eschar buildup on the electrode surface. 82 However, how the surface quality of the electrode influences particulate production is not yet understood. Thus, there is a need for experimental studies to define conditions and device design that could ensure that surgical smoke production is reduced. This could include consideration of the tissue type, the electrode design, and coating, while also understandings the influence of the cutting power settings used. This could be complemented with computational models that predict the conditions that reduce smoke production and identify the conditions that may result in smoke-inducing temperatures. Nine states in the United States of America have taken their own steps to implement legislation to mandate the usage of surgical smoke evacuation systems in operating theaters. 44 However, it is up to the hospital to decide what type of dedicated surgical smoke evacuation is used. A variety of smoke evacuators specifically designed for surgical smoke are commercially available. However, there are few studies investigating the performance of surgical smoke evacuation devices, which is important as their use is recommended by leading organizations (NIOSH, OSHA, and AORN). The usage of a portable smoke evacuation system can evacuate fine particulate ~5 times better than a handheld aspiration hose held 5 cm away from the cut site. 72 Another study assessed surgical smoke and aerosol evacuation during electrosurgery, ultrasonic cutting, and CO 2 laser ablation, using a high-speed backscatter illumination technique. 83 This provided qualitative information regarding evacuation performance and showed that a benchtop device, and an electrosurgical pencil with integrated suction, both resulted in apparent effective smoke evacuation. 83 It would be useful to investigate, quantitatively, the performance of several surgical smoke evacuation devices in a controlled experimental environment and at the point of care. Furthermore, the minimum suction flow rate required for surgical smoke evacuators has not been measured or quantified. Such devices could ultimately enable the development of advanced diagnostic approaches. Generally, all airborne particulates are harmful to inhale, and the size only affects the severity. Insoluble fine particulate matter (PM 2.5 ), can reach the alveolar region of the lung where clearance occurs through phagocytosis by alveolar macrophages, which may induce inflammatory and pro-thrombotic responses. 23 Rats exposed to filtered exhaust surgical smoke (particle size <0.5 µm) demonstrated pathologic effects such as emphysema, interstitial pneumonia, and bronchiolar hypertrophy and hyperplasia. 31 Furthermore, it was demonstrated that an 8-hour shift in an operating theater could be equated to smoking 27 to 30 cigarettes. 41 The work of Casey et al 29 identified that 90% of particles in surgical smoke are within the PM 10 classification for all cutting conditions. Furthermore, for all cutting conditions, 50% of particles fall under the PM 2.5 classification except for ultrasonic cutting of bone, which was just above the limit. The sizes of particles identified in this study would suggest that the correct implementation of a smoke evacuator equipped with a HEPA or ULPA filter would be able to remove more than 90% of all particulates created. 29 However, given the reported inconsistent use of smoke evacuation and protection measures, and reports of sino-nasal symptoms, 48 , 49 it is important that the toxicological response in humans is explored as this has not been studied in detail to date. An in vitro study administered culture media containing particulate from electrosurgery of human breast tissue to human small airway epithelial cells and mouse macrophages for a 24-hour period, after which cell viability, lactate dehydrogenase, and superoxide production were examined, and from which statistically significant cytotoxic effects were observed. 84 A comprehensive in vitro analysis of surgical smoke and aerosol exposure to relevant cell types, such as small airway epithelial cells, in a bioreactor configuration that best recapitulates inhalation/exposure to humans, may provide more relevant information regarding the mechanisms that may cause adverse health effects. Further research on surgical smoke is required to quantify the measurable risk to health it poses, the cutting conditions under which it is generated and to develop advanced diagnostic approaches using this information.

Tissue profiling during electrosurgery is a promising area of research, which aims to improve surgical decision-making. 73 However, time-consuming sample preparations, as well as the need for additional experienced personnel often make the translation of technologies to the operating theater difficult. The ultimate goal is to provide instantaneous information regarding the pathology and disease state of tissue to the surgeon, who can therefore make a more informed decision regarding a procedure. Histologic examination is used intraoperatively to determine whether any remnants of cancerous tissue are left behind after tumor resection. This significantly reduces the recurrence of cancer, and consequently, the need for secondary surgeries—particularly for breast-conserving surgeries. 74 , 75 However, the extra time involved in carrying out histologic analysis means that the surgery is disrupted, and the patient remains under anesthesia. Secondary surgery to remove cancerous tissue that may have been missed during the first procedure is a significant burden on health systems. 76 Radiography, ultrasound, and magnetic resonance imaging can be used to help locate and judge the size of tumors preoperatively but lack cellular level resolution. A real-time technique shown to be feasible for tumor margin assessment, at the point-of-care in humans, is the rapid evaporative ionization mass spectrometry (MS) based “iKnife” device. The iKnife aspirates surgical smoke from electrosurgical cutting converting it into the gas-phase ionic species needed for MS analysis. 73 The technique compares analyzed surgical smoke against a spectral reference library developed using ex vivo benign and malignant tissues. The technique has demonstrated sensitivity (the ability to correctly identify diseased tissue) of 95.1% for stomach tumors and 100% for breast and brain tumors. 73 Also, specificity (the ability to confirm the tissue is not diseased) was shown to be 92% for lung tumors and 100% for breast, brain, and stomach tumors. More recent studies have used iKnife on ex vivo uterine (n = 150, 85% sensitivity, 93% specificity) 77 and cervical cancers (n = 87, 100% sensitivity, 100% specificity). 78 Current barriers for the translation of this technology to the intended clinical setting include the cost of instrumentation and the effort and time needed for the development of the medical device as well as the spectra database, as collection and validation of the data are time-consuming. 73 Desorption electrospray ionization mass spectrometry (DESI-MS) is also being developed for the intraoperative diagnosis of human brain tumors. 79 , 80 DESI-MS is a technique, in which a spray of charged solvent impacts the target tissue and desorbs secondary droplets containing analytes that enter the mass spectrometer similar to the iKnife technology discussed above. Using DESI-MS, a classifier was developed using supervised machine learning based on 36 glioma and 19 meningioma samples. The algorithm was then applied to 32 samples from 5 patients undergoing brain tumor resection. All samples in the study were cancerous, however, the developed classifier demonstrated the ability to distinguish between types of brain tumors, which was validated against a histologic analysis of each tumor. 79 Further to this, DESI-MS was used in a study of grey matter (n = 223), white matter (n = 66), gliomas (n = 158), meningiomas (n = 111), and pituitary tumors (n=154) from 58 patients and obtained an overall sensitivity of 99.4% and a specificity of 99.7% when distinguishing tumor type. 80 Another technology that has shown potential is differential ion mobility spectrometry (DMS). 81 DMS can sample surgical smoke directly and the main advantage over MS is that it can operate at atmospheric pressure. DMS separates molecules according to their ion mobility and electrical charge in conjunction with a radiofrequency waveform orthogonal to the sample flow, which further discriminates the molecules. It is a qualitative technique because DMS dispersion plots do not explicitly specify the ions it detects, in contrast to MS. It has been shown, in a proof-of-concept study, to be capable of deciphering between 10 different types of porcine tissues (grey matter, white matter, liver, skeletal muscle, subcutaneous fat, lung, renal cortex, skin, tongue, and cardiac muscle) with 95% accuracy. 81 Sample adherence to the electrosurgical electrode that affected smoke production, data communication delays between the sampling system, and malfunctions of the preprocessing unit or the DMS device need to be addressed before it can translate from research to clinical use.

Surgical procedures with the potential to liberate droplets and suspended particles into the air are termed “aerosol-generating medical procedures” or aerosol-generating medical procedures (AGMPs). These include procedures that may increase the likelihood of aerosol release from breathing, coughing, sneezing, and even talking. AGMPs include mechanical aerosol generation arising from surgical cutting with high-energy devices used in surgery, such as powered surgical instrumentation. 20 Aerosols are a concern as they can contain respirable particulate matter and furthermore carry the potential to contain small transmissible pathogens, such as viruses. Electrosurgery creates a by-product known as “surgical smoke”. This smoke emanates from the surgical cut site creating a potent odor, as well as reducing visibility for the surgeon. It disperses throughout the operating theater unless some form of evacuation mechanism is in place and there is evidence that it may carry hazards related to the particulate burden, chemical composition, and biological activity. 21 Thus, extra precaution such as smoke evacuation is necessary when conducting these types of procedures. Understanding of surgical smoke composition can be limited by the restricted size range that ambient particulate measuring devices can characterize, typically having resolutions up to ~10 µm. The United States Environmental Protection Agency ( https://www.epa.gov ) classifies airborne particles according to their aerodynamic diameter: ≤10 μm diameter particles (PM 10 ) are inhalable and the coarse fraction (2.5–10 μm) will deposit in the respiratory tract and be removed by mucociliary clearance. 22 Insoluble fine particulate matter, ≤2.5 μm diameter particles (PM 2.5 ), can reach the alveolar region of the lung where clearance occurs through phagocytosis by alveolar macrophages, which may induce inflammatory and pro-thrombotic responses. 23 Particles with aerodynamic diameters <1 μm are commonly referred to as submicron, whereas particles<0.1 μm are referred to as ultrafine. Ultrafine particles are small enough to potentially enter the circulatory system through the respiratory system. 24 Surgical N95 respirators and high-efficiency particulate air (HEPA) filters remove particles larger than 0.3 μm and ultra-low particulate air (ULPA) filters (used in surgical smoke evacuators) remove particles larger than 0.12 μm. 25 Aerosol measuring devices do not enable access to analyzed particulate for further analysis, for example, scanning electron microscopy/transmission electron microscopy. Depending on the analytical techniques used, surgical smoke has been reported to contain particles of varying size, for example, cascade impaction (0.2–9.8 µm, 0.1–10 µm), 26 condensation particle counters (0.01–1 µm), 27 and electrical low-pressure impactors (ELPI) (0.007–10 µm). 28 Particles in the PM 10 and PM 2.5 categories are typically reported in terms of their mass concentration. However, submicron and ultrafine particles, which have negligible mass compared with larger particles, are best quantified in terms of number concentration. Instruments are available to detect the mass, volume, and number concentrations of PM 10 , PM 2.5 submicron, and ultrafine particles (cascade impaction, ELPIs, condensation particle counters, and laser diffraction), however, these types of instrumentation may not fully characterize the entire spectrum of particulate, especially larger particles, exhibited in surgical smoke due to their restrictive sizing limits. Electrostatic precipitation is an approach that has been used for particle collection from surgical cutting to facilitate particle sizing as well as morphologic, elemental composition, and biological activity assessment of the particulate matter. 29 Chemicals that are potentially carcinogenic, neurotoxic, and mutagenic (such as acrylamide, acetaldehyde, formaldehyde, benzene, cyclohexanone, toluene, ethylbenzene, and xylene) have been identified in surgical smoke. 30 Inhalation of low levels of surgical smoke in rats has been associated with pathologic events, such as emphysema, interstitial pneumonia as well as bronchiolar hypertrophy and hyperplasia. These pathologies are correlated with the duration of smoke exposure and the number of consecutive days exposed. 31 Surgical smoke may possibly serve as a transportation mechanism for harmful biologically active material during surgery (cancerous cells and viruses). AGMPs have come into focus as infection prevention and control advice is sought by health care workers. It has been established that viable cells are contained in non-airborne surgical cutting by-products such as bone dust and chips, 32 but conflicting research exists regarding whether surgical smoke contains viable biological agents. Viable melanoma cells were found in the plume created by electrocautery of mouse melanoma cells. 33 Conversely, no viable cells were found in the smoke generated by electrosurgery during tumor dissection, 34 and more recently, it was reported that no viable SCC7 mouse cancer cells were identified in the smoke generated by either electrosurgery or RF ablation. 35 Viable viruses have been identified in surgical smoke, which supports the possibility of viral transmission through surgical smoke. 36 Intact viral DNA has also previously been identified in the plume collected during carbon laser therapy of papillomavirus-infected verrucae, 37 and subsequently, the transmission of disease and infectivity was confirmed by inoculation of the laser plume into the skin of calves. 36 Surgical smoke is a term commonly associated with electrosurgery and cautery devices. However, airborne by-products can also be generated by ultrasonic aspirators/scalpels, high-speed drills, burrs, and saws (among others). One investigation of ultrasonic aspirators found no viable cells liberated during tumor dissection in the aerosolized by-product. 34 It was recently reported that ultrasonic scalpels aerosolize viable cells but, the study in question involved the cutting of cultured cancer cells rather than bulk tissue. 35 Aerosolized by-products collected from the ultrasonic ablation (Ultracision Harmonic scalpel generator 300; Ethicon Endo-Surgery) of cultured cancer cells (SCC7) were injected subcutaneously into 5-week-old male C3H mice and an increase in tumor prevalence was observed at 2 weeks. 35 Histologic and biochemical analyses demonstrated that these cancer cells were identical to the cancer cells liberated by the ultrasonic scalpel, suggesting that viable tumor cells can be transported through surgical smoke from tumor dissection by ultrasonic scalpel. 35 The study also showed that there is a dependence on the distance, at which surgical smoke is collected, and the likelihood of containing cells, as cells were always found 5 cm away from the surgical site whereas cells were only found in 8% of the cases at 10 cm away. 35 A study investigating vapor from bone-cutting instruments added the aerosol from blood containing human immunodeficiency virus-1 (HIV-1) to MT-2 cells, which became HIV-1 positive as a result. 38 The experiment was conducted in a biosafety cabinet and tools were activated within a suction canister, where the aerosol/surgical smoke was evacuated into a sterile culture medium at a flow rate of 0.8 liters/minute. A bone saw was partially submerged in a fluid (saline) for 1 minute, while 9 mL aliquots of blood containing HIV-1 were pipetted over the blade. 38 Similarly, a bone router operating at 30,000 revolutions per minute was examined in the same manner, but without submersion in the fluid. 38 Electrocautery was examined by using cut and coagulation modes on thawed fresh-frozen human skin and muscle while blood containing HIV-1 was pipetted over the cut site. 38 The study observed no HIV-1 infected MT-2 cells from electrocautery of blood containing HIV-1 when the router was not submerged in fluid. 38 Electrosurgical smoke has previously been analyzed to study particle production generated during electrosurgery for soft tissues, such as muscle, liver, and fat. 28 However, the physical characteristics of the particulate generated during bone tissue cutting and any influence that the cutting modality has on particle size are not yet fully understood. An ex vivo study on animal tissue (liver and bone) demonstrated the varied morphology of airborne particulate produced during the use of a sagittal orthopedic saw, electrosurgery, and ultrasonic cutting. 29 It was also demonstrated that electrosurgical smoke and aerosolized particulate from the ultrasonic cutting of lamb liver cutting contains metabolically active cells whereas bone saws and ultrasonic cutting of bone do not. 29 Although it has been reported that cell viability is altered if directly subjected to mechanical stimuli and/or exposure to temperature, 39 how the cutting mechanism and temperature govern the viability of cells within aerosolized particles needs further investigation. It has been stated that laser ablation and electrosurgery of 1 g of tissue produce the equivalent amount of mutagenic smoke to 3 or 6 unfiltered cigarettes, respectively. 40 Furthermore, using similar techniques to, 40 it was demonstrated that an 8-hour shift in an operating theater could be equated to smoking 27 to 30 cigarettes. 41 The Association of periOperative Registered Nurses (AORN) has been active to date in raising concerns around surgical smoke in the operating room and educating people on best practices relating to surgical smoke evacuation. 42 An estimated 500,000 surgery-related health care workers including nurses, surgeons, surgical technologists, certified nurse anesthetists, product representatives, as well as patients are exposed to surgical smoke each year in the United States if inadequate evacuation measures are in place. 43 Occupational Safety and Health Administration (OSHA) currently has no specific standards to protect people against surgical smoke exposure. 43 To date, 9 United States (Rhode Island, Colorado, Kentucky, Oregon, Illinois, Arizona, Washington, Georgia, and Connecticut) have enacted surgical smoke evacuation laws to protect perioperative nurses and the surgical team by enforcing the usage of surgical smoke evacuation systems. 44 The health effects associated with the constituents already identified in surgical smoke include acute and chronic respiratory changes (eg, emphysema, asthma, and chronic bronchitis), anemia, anxiety, carcinoma, cardiovascular dysfunction, colic, dermatitis, dizziness or light-headedness, eye irritation, headache, hepatitis, HIV, hypoxia, lacrimation, leukemia, nasopharyngeal lesions, nausea or vomiting, sneezing, and weakness. 45 Operating room employment was not associated with an increase in the incidence of lung cancer due to long-term surgical smoke exposure as a surgical team member. 46 Acute respiratory symptoms have been associated with surgical smoke exposure, with a report stating that of 50 third-year surgical residents from various specialties, 58% experienced the sensation of lumps in their throats and 22% experienced sore throats. 47 Neurosurgery had the highest rate of exposure with an average of 24.1 minutes per surgical procedure and all residents from this specialty (n = 13) experienced respiratory symptoms. 47 Strikingly, it has been reported that the incidence of respiratory issues (bronchitis, asthma, sinus infections/problems, and allergies) in perioperative nurses is twice that compared with the general population. 48 , 49 A study also observed a statistically significant association between the prevalence of severe persistent asthma among operating theater nurses when compared with administrative nurses. 50 Two case reports to date suggest the likely transmission of inhaled virus particles during a procedure causing papillomas in members of the surgical team. Laryngeal papillomas in a surgeon who had administered laser therapy to patients with anogenital condylomas were reported in a study to have been caused by inhaled human papillomavirus virus particles. 51 The surgeon in this case, who regularly operated on anogenital condylomas, was otherwise healthy but presented with persistent hoarseness for 6 months. The hospital had no dedicated surgical smoke evacuation so an “ordinary smoke evacuator” was used in conjunction with conventional masks, gloves, and eye protection. The laser used in this case was an Nd:YAG laser with a maximum power of 100 W. DNA hybridization of the papillomas of the surgeon revealed human papillomavirus virus DNA types 6 and 11, which are known to contain the same viral DNA types as those the patient had. The exact mechanism of contamination, in this case, cannot be proven. The second case report involving a member of the surgical team occurred when a 28 years old operating room nurse presented with recurrent laryngeal papillomas. 52 The nurse regularly assisted in electrosurgical and laser excision of anogenital condylomas. The virological institute involved in the study confirmed the high probability of contraction of laryngeal papillomatosis in the nurse due to occupational exposure. 52

Adequate forms of suction and evacuation are needed to remove surgical smoke from the operating theater. The National Institute for Occupational Safety and Health (NIOSH) advises local exhaust ventilation (LEV) in conjunction with room ventilation such as unidirectional laminar flow (UDF) for surgical smoke removal ( https://www.cdc.gov/niosh ). OSHA does not have any specific standards around the use of surgical smoke evacuation. 43 Smoke evacuators usually incorporate a benchtop vacuum pump with tubing leading to the inlet where smoke is expelled. The inlet of the suction device can be external to the tool or can be built-in to the electrosurgical pencil or even retrofitted to electrosurgical pencils that do not have built-in suction functionality. 53 Surgical smoke evacuation devices are typically fitted with a ULPA and/or HEPA filter. The suction of blood or saline into surgical smoke evacuators can cause damage to these filters and cause performance issues but can be avoided with the use of a fluid trap. Laparoscopic procedures that produce surgical smoke need evacuation to clear the field of vision for the surgeon. Releasing cannulas to allow smoke escape should be avoided as the high concentrations of surgical smoke can be ejected toward the surgeon or other team members. Laparoscopic surgical smoke filtering devices are also available. 54 A study investigating commercially available portable surgical smoke LEV systems found that the highest smoke reduction (99% ± 1%) was observed with maximum suction and a UDF rate of 10,500 m 3 h -1 and with minimum suction and a UDF rate of 7500 m 3 h -1 smoke reduction dropped to 62% ± 12%. 55 However, AORN surveys report feedback from surgical staff that excessive noise is a deterrent for LEV use for surgical smoke removal. 56 , 57 Surgical masks are commonly worn to protect against splashes and droplets in the region of the nose and mouth of the wearer. These masks provide little or no protection against aerosol inhalation. 25 This is due to surgical masks not being close-fitting and therefore, are prone to leakage points where aerosols can enter. 58 Filtering face-pieces (FFP) offer, on average, 11.5 to 15.9 times greater protection than regular surgical masks (tested outside to inside). 59 The European Standard for respiratory protective devices (EN 149:2001) has classifications FFP1, FFP2, and FFP3 having minimum filtration efficiencies of 80%, 94%, and 99%, respectively down to particle size of ~0.01 µm. 59 However, virus particles are known to be on the nanometer scale. 60 A 2010 AORN-commissioned survey conducted across North America assessed operating theater personnel compliance with “often” or “always” usage of wall suction filtration, the use of smoke evacuation, and the use of high-filtration face masks such as N95s or equivalents. 57 The reported frequency of usage of a smoke evacuator was highest in condyloma or dysplasia treatment with 68% and 84% when using electrosurgery or laser, respectively. However, the other electrosurgical procedures reported only 11% to 24% usage of a surgical smoke evacuator. Laser procedures had compliance with smoke evacuator use ranging from 16% to 84%. Ultrasonic scalpel procedures that used smoke evacuation were reported at 11%. The usage of smoke evacuation through wall suction varied from 19% to 83% across all surgical procedures. “Often” or “always” usage of N95 or other NIOSH-approved respirators was also surveyed, and it was revealed only 1% to 2% used these during electrosurgical procedures except for condyloma or dysplasia treatment, which was higher at 16%. Laser procedures used reported approved respirator usage in the range of 2% to 21%. Ultrasonic scalpel procedures had 2% compliance with respirator usage. 57 It is important to note that these compliance rates may have improved, particularly due to the coronavirus disease 2019 (COVID-19) pandemic, which motivated work investigating aerosol formation from surgical cutting instruments such as micro-debridement, high-speed drilling, cautery, and ultrasonic cutting. 61 – 64 The University of Illinois Hospital, Chicago, identified in 2019 that <0.5% of invasive procedures using energy-based devices used surgical smoke evacuation. 65 In 2020, after the implementation of a smoke evacuation policy and appropriate evacuation devices, reported compliance rose to 30% (664 of 2224 procedures), which the report admits was helped by the pandemic at the time. 65 AORN has published clear guidance on surgical smoke safety and preventative measures, which outline what type of smoke evacuation device is appropriate for small (eg, wall suction with inline filter) and large amounts (smoke evacuation and filtration device) of surgical smoke. 66 The guidance also states the importance of respiratory protection [personal protective equipment (PPE) including N95 facepiece], as secondary protection from surgical smoke. 66 However, PPE should be used as a protective measure and not control infectious disease transmission. 67 Surgical smoke evacuation and protection devices are commercially available, however, usage is highly varied as stated by AORN. 57 Although recent studies (since the COVID-19 pandemic began) have highlighted the lack of significant evidence of disease transmission through surgical smoke, 68 it is accepted that surgical smoke can be generally dangerous and despite advocation from leading organizations, smoke evacuation devices still are not always used. 69 , 70 The scientific research investigating the constituents of surgical smoke from energy-based instrumentation is still growing and hopefully will serve to increase awareness and compliance with protection strategies. The following section summarizes studies that have applied various analytical techniques to investigate different aspects of surgical smoke. Methods of studying particle pollutants have been developed for many industrial applications where exhaust fumes are vented into the atmosphere, such as power generating facilities, cement mills, and aluminum smelting. There are various methods that can be used to separate particulate from a flowing gas, 22 including but not limited to centrifugal systems, wet scrubbers, fabric filters (HEPA/ULPA), and electrostatic precipitation. Studies have used various approaches to characterize surgical smoke and aerosols, however, the wide range of surgical variation that can occur (tissue type, device type, and experimental setup) makes comparisons between different studies challenging. 26 – 28 , 71 , 72 Previous studies have used off-the-shelf aerosol measurement equipment and have focused on capturing smaller particles (<10 µm). This is partly due to the issues of detecting particles of larger mass, due to gravitational and inertial effects, but also because smaller particles are associated with deeper penetration of the lung if respired and therefore, a greater chance of adverse health effects. Cascade impaction is a particle sizing method that passes particulate through a series of graduated chambers that have varying orifice sizes, allowing particle size distributions to be obtained by examining the amount of particulate contained in each chamber. Condensation particle counters are an optical technique that enlarges particles in a supersaturated gas allowing smaller particles to be detected. An ELPI is a device that utilizes a cascade impactor and applies a charge to particles before they deposit on a grounded impaction surface where an electrical signal is detected that corresponds to the mass of the particle. One study analyzed particles in the range of 0.1 to 0.8 µm from a CO 2 laser used during laparoscopic surgery for endometriosis, using cascade impaction, with the largest orifice being 9.8 µm. 26 Cascade impaction was also used in a study involving cautery during laparoscopic procedures and cutting of ex vivo tissue. 27 It was found that particles of size 0.05 to 28 µm were present in the surgical smoke using an impactor with a resolution of 0.1 to 10 µm (orifice size was 28 µm for the 10 µm tray). Electrocautery, laser ablation, and ultrasonic cutting particulate were analyzed during 6 different surgical procedures using a condensation particle counter that measured sizes in the range of 0.01 to 1 µm. 71 It was also used to detect particles from peritonectomy and colon/rectal cancer surgery with sizes 0.02 to 1 µm. 72 Particles from the electrosurgical cutting of ex vivo porcine tissue were analyzed in a recent study using an ELPI with a resolution of 7 nm and 10 μm. 28 Electrostatic precipitation for the collection of particles from surgical cutting presents an alternative to the aerosol measurement equipment mentioned. 29 It is a technique that allows for the separation and collection of particulates from a flowing gas and facilitates further analyses such as microscopy. The other measurement techniques mentioned such as cascade impaction, condensation particle counters, and ELPIs do not readily allow for access to particulate in this manner for subsequent analysis and imaging.

This article has presented a detailed review of energy-based surgical instrumentation and how they have developed since their inception, AGMPs, surgical smoke and aerosols produced during procedures and the health concerns associated with them, surgical smoke evacuation modalities and protection, and developing tissue identification techniques. In summary, surgical smoke and aerosols are occupational hazards in the operating theater and put the health of the surgical team at risk if not properly handled with surgical smoke evacuation technology and correctly used PPE. Although the health concerns have been acknowledged by many leading organizations and many studies have identified harmful constituents in surgical smoke, further research is required to conclusively quantify the measurable risk to health it poses to humans, particularly operating theater staff. The implementation of a surgical smoke evacuation policy and appropriate evacuation devices will help mitigate health concerns through the forced removal of the harmful constituents that have been identified in surgical smoke from the operating theater. Emerging smoke evacuation technology that obtains diagnostic information regarding tissue pathology from surgical smoke would not only help eliminate health concerns but revolutionize surgical resection of diseased tissue and positively affect patient outcomes.

Surgery intervention is necessary to treat many medical conditions, 1 and the World Health Organization (WHO) estimated that 312.9 million operations took place in 2012 (across 66 member states of the WHO), an increase from the 2004 estimate of 226.4 million operations. 2 As the rate of occurrence of cancers, cardiovascular disease, and traumatic injuries increases, the impact of surgical intervention on public health systems will continue to grow. The surgical procedure itself is reliant on surgical instruments that surgeons have at their disposal for tissue cutting and manipulation. Thermal energy for cauterization has been used for thousands of years. Early in the 19th century, the French physicist Becquerel described the use of direct current to heat a wire, which was used to cauterize human tissue. This became known as “electrocautery”, with reported use of the technique on a patient as early as 1851. 3 A key development in surgery came when the physicist, Dr William T. Bovie, created the first electrosurgical device for tissue cutting, 4 which also addressed the significant issue of blood loss during surgery by producing superior coagulation and vessel sealing compared with methods of the time. The 20th century saw the evolution of energy-based surgical instruments including electrosurgical devices, ultrasonic scalpels and high-speed saws, drills, and burs. Differing from the conventional scalpel, these devices harness various forms of energy such as electrical, kinetic, and heat to produce the desired tissue effects such as cutting, desiccation (tissue dehydration), coagulation (protein denaturation to seals blood vessels), or fulguration (superficial tissue destruction), which have revolutionized how dissection and tissue removal are carried out. These devices provide the surgeon the ability to operate with accuracy and limit unnecessary destruction of healthy tissues and cells, which positively affects patient outcomes. The 20th century saw the range of conditions surgery was used for expansion providing a larger market for electrosurgical devices and innovations. The impact of electrosurgery has been such that it is now rare for any surgery to take place without some form of an energy-based device being applied to the patient. 5 Ultrasonic devices were initially used for dental applications in the 1950s, this expanded to use in cataract surgery in the 1960s, and later to soft tissue removal and brain tumor excision. 6 Clinical studies on meningiomas, neurinomas, gliomas, and chordomas helped outline the distinct advantages of ultrasonic devices, including efficient intracapsular tumor removal and lack of tissue traction, which reduced tension on surrounding nervous tissue. 7 A particular disadvantage was the limited ability to remove extremely calcified and dense fibrous tumors, however, this was outweighed by its benefits of improved tissue resection and reduced blood loss. This made ultrasonic devices attractive for general surgery and expedited their translation to specialty areas of surgery. 6 Shortly after, research began on the interaction of laser light with biological tissues at a superficial level. 8 By the early 1980s, regular use of lasers for cutting and ablation in laparoscopic surgery was reported. 9 Carbon dioxide (CO 2 ), neodymium-doped yttrium aluminum garnet (Nd:YAG), and argon lasers have all been implemented in surgery. 10 Common energy-based surgical devices utilize electricity, ultrasonic displacement, lasers, microwaves, and radiofrequency (RF) ultimately resulting in varying levels of tissue and cell death (necrosis) and control of blood loss (hemostasis). The effect on the tissue will vary depending on the heat produced due to the applied energy. 11 , 12 Ultrasonic devices produce temperatures at or below 80°C, which is comparatively low, and thus can achieve both dissection and vessel sealing without charring of tissue. 11 In contrast, electrosurgery can result in significant charring of tissue due to high temperatures. This is more likely to occur with an increased duration of device activation on the tissue. Heat generation in electrosurgery depends on several factors (current density, time, electrode size, tissue conductivity, and current waveform), which will be discussed further. 12 Protein denaturation causing coagulation is said to occur between 70°C and 80°C, which aids in vessel sealing whereas dehydration and desiccation occur when intracellular temperatures reach above the boiling point of water (100°C), resulting in explosive vaporization of cells and a cutting effect. Temperatures above 150°C cause carbonization and can be used when fulguration is desired. Choosing an energy-based instrument for a surgical procedure requires a fundamental understanding of how each device works and its effect on the target tissue. The terms “electrocautery” and “electrosurgery” are often used interchangeably but represent two distinct modalities. In electrocautery, direct current is used to heat an object, that is, cutting tip/wire, which is then used to burn (cauterize) a specific site on the patient for removal purposes and/or to stop bleeding. In electrocautery, no current enters the patient’s body. This is distinct from electrosurgery, in which alternating current flows through the body from the cutting device to a return electrode placed on the patient. Electrosurgery is characterized by the passage of RF electrical current from an active electrode, through the patient’s tissue, to a return electrode. This creates an uninterrupted pathway for electrons to flow, that is, a circuit, which obeys Ohm law: V = IR where I is the intensity of the current, V is the voltage (force driving the current against the resistance), and R is the resistance of the tissue. The active electrode applies current to the tissue in a very small area causing resistive heating, also known as Joule heating, as well as the elevation of intracellular temperatures. Using the Joule-Lenz law an expression can be produced for the thermal energy generated in the tissue: Heat energy ( Q ) is proportional to the current density [current per cross-sectional area ( A )], time ( t ), and resistance (R). Therefore, the heating effect intensifies with reducing electrode surface area. Various electrode geometries are commercially available (eg, point, hook, blade, and among others) with specific surface areas to achieve the desired tissue effect, such as cutting or coagulation. Modern electrosurgical generators can obtain desired tissue effects such as “pure cut” using a sinusoidal voltage waveform at ~400 kHz and “coagulation” using a modulated sinusoidal waveform of frequency >400 kHz. 13 Electrosurgical generators can facilitate monopolar or bipolar energy delivery. Monopolar electrosurgery passes the electrical current from the active electrode through the patient’s body to a dispersive return electrode connected to the generator (ground). The relatively large size of the dispersive electrode allows safe passage of current through the body and heat dissipation to avoid burns. In the bipolar modality of electrosurgery, the passage of current from the active electrode to patient tissue and back to the return electrode occurs within the handpiece of the device—grabbing tissue-like forceps and applying energy to the tissue between the electrodes for cutting or coagulation. The percentage of time that the RF energy is applied while the device is activated (the “duty cycle”) will alter the tissue effect. Modern electrosurgical generators can manipulate the outputted waveform to favor cutting, coagulation, desiccation, or fulguration. In monopolar electrosurgery, pure cutting will have a duty cycle of 100%, whereas coagulation can be conducted with a duty cycle of 6% (meaning energy is not applied 94% of the time) but uses a higher voltage than the pure cutting mode. Combinations of cutting and coagulation, typically known as “blend”, can be obtained with duty cycles of 25%, 40%, and 50% for example. 13 Radiofrequency current can be used for laparoscopic electrosurgery. The principles are the same, and monopolar and bipolar modalities are available. Argon beam coagulation is another modality that utilizes RF current. In this technique, a sheath of argon gas surrounds the electrode and is directed toward the tissue, and aids in the conduction of current to the tissue by ionization. In contrast to electrosurgery, contact is not made with the tissue in argon beam coagulation. The electric arc formed between the electrode and the tissue allows RF current to flow and resistive heating creates the desired tissue effect, but at a more superficial level than conventional electrosurgery. Temperature generation during the application of electrosurgical techniques has been shown to exceed 200°C. A study examining the performance of monopolar electrosurgery at 40 W on porcine muscle measured temperature using thermocouples (verified by infrared thermometer) and reported that a peak temperature of 100.1°C arose at the hook-cutting tip. 14 Another study examining monopolar electrosurgery, also at 40 W, on the skin of Yucatan swine, measured a peak temperature of 241°C at the tip by infrared thermal imaging. 15 Bipolar electrosurgery has been reported to produce a peak temperature of 110°C at the cutting tip, using infrared thermal imaging during laparoscopic dissection in the peritoneal cavity of pigs. 16 Ultrasonic devices convert electrical energy into high-frequency vibratory energy using piezoelectric transducers. Ultrasonic device tips can oscillate in the range of 20 to 60 kHz. When the oscillating tip meets tissue, it induces the breakdown of hydrogen bonds, increased cellular friction, and protein denaturation and can achieve desired effects such as cutting or coagulation. Direct mechanical impact (sometimes termed “jackhammer effects”) and cavitation are important components of cutting physics in ultrasonic devices. For tissues that have higher protein densities and mineralized tissue, the linear reciprocating movement of the ultrasonic device tip causes the tissue to be stretched beyond the elastic limit of the tissue and results in a cutting action. 11 Cavitation effects are more dominant in softer tissues of lower protein densities, such as the liver. 5 Large transient pressure changes resulting from the tip movement lead to the vaporization of intracellular water at low temperatures. Suspended gas bubbles within the tissue are trapped at the solid interface of the tool. These bubbles expand and collapse causing a rapid release of energy that ruptures cells and leads to the precise cutting action. 5 The temperature ultrasonic devices produce typically remains below 80°C (minimizing charring, desiccation, and zone of thermal injury) and they seal blood vessels by protein denaturation. 11 , 12 A study of an ultrasonic scalpel used on porcine muscle demonstrated a peak temperature of 71.3°C at the tip when applied for 15 seconds. 14 The same study investigated the duration of cutting and power levels of electrosurgery and ultrasonic cutting and reported that peak temperatures increased with a higher power setting and duration of cutting (5, 10, and 15 seconds cutting intervals were tested) for bother surgery types. Bone-cutting burs, drills, and saws utilize rotation/oscillation to mechanically abrade tissue resulting in temperatures >50°C. Infrared thermal imaging during controlled high-speed sawing of the ovine metatarsal revealed a peak temperature of 54.84°C at the endosteal surface. 17 The results of that study led to the development of a multiscale model (osteocyte-osteon-whole bone) that was able to accurately predict the temperature in the bone tissue matrix and embedded cells. 17 The impact of design modifications and surgical techniques on temperatures experienced by bone tissue and cells was explored by these experimentally informed computational models. 17 High-speed surgical saws remove bone tissue efficiently, however, the impact of the induced temperature elevations in bone tissue is less well understood. Surgical saw blade designs now include features such as a gap in the geometry to aid the removal of bone chips and dust as it is formed, which may reduce heat generation. Feed-rate of surgical saws has also been identified as an important factor in heat generation. 18 Furthermore, the duration of exposure of the bone tissue to temperatures above 47°C is directly proportional to the volume of bone that experiences thermal damage. 19 Surgical laser cutting devices utilize electromagnetic energy to achieve the desired action. Commonly used types of lasers in surgery include Nd:YAG, argon, and CO 2 lasers. Most commercially available lasers for medical purposes operate in ultraviolet to infrared frequencies. High-density energy is absorbed by the tissue, which results in heat generation and subsequent cutting/coagulation. The term “power density” is used to describe the amount of irradiation experienced by the tissue. This is measured by dividing the power (energy per second) by the cross-sectional area where the laser is applied. The amount of time the tissue is exposed to the laser light and the wavelength also play important roles in the photo-thermal and photo-chemical induced effects of laser application. 5 Photo-thermal effects refer to laser-produced heat for tissue destruction, whereas photo-chemical effects are nonthermal and occur at low levels of irradiance but induce chemical reactions and inactivity in cells. Surgical devices can also be contact or noncontact depending on the procedure. Direct contact of the laser instrument with the target tissue minimizes the energy losses due to reflection. Noncontact laser devices are operated at a distance from the tissue.