The perils of surgical smoke in the OR and how Ultravision overcomes the limitations of other solutions
Healthcare professionals have been aware of surgical smoke in the OR for many years but may not be fully educated on the complexities of managing it.
Here we summarise what is known on the subject and how manufacturers have sought to deal with it. We also uncover the limitations of other systems and how Ultravision is advancing new protocols.
Surgical smoke, sometimes also referred to as surgical plume, cautery smoke, vapours, mist, diathermy plume, and bioaerosols, is produced by all modern, powered surgical instruments. In an attempt to standardise a definition AORN, one of the most vociferous surgical smoke control advocates globally, refers to it as:
“the visible and malodorous by-product released into the air as a result of disruption and vaporisation of tissue and cellular matter by the energy generating devices commonly used in surgery (AORN 2017)”
Surgical smoke has many components. Approximately 95% is water and steam. The other 5% comprises chemicals, blood, tissue fragments, macromolecular cellular constituents (lipids, carbohydrates, nucleic acids, for example) and salts[i].
Exposure to surgical smoke is of increasing concern to healthcare professionals globally and is now generally acknowledged to be a workplace hazard[ii]. As a result, legislation is being introduced in some countries that will result in mandatory controls to limit surgical smoke exposure for healthcare professionals. That said, the introduction of legislation has been slow and is currently largely limited to those countries that historically have led the development of occupational health and safety initiatives. In many countries, despite access to the same data, the risks remain largely ignored.
The risks to healthcare professionals that are associated with surgical smoke exposure can broadly be categorised as “chronic” (due to long-term, repeated exposure), or “acute” (due to a single-dose exposure). This is because surgical smoke contains chemicals, which represent a long-term risk; and has been reported to contain active biological agents such as viruses and bacteria, which represent a short-term infection risk.
Chronic exposure risks of surgical smoke for healthcare professionals
Approximately 77% of the particulate matter in surgical smoke is less than 1.1 microns (μm) with a mean diameter of 0.07μm[iii]. However, surgical smoke can also contain extremely high levels of ultrafine particles ranging from 10nm to 1μm[iv]. At sizes smaller than 5 μm, surgical mask filters become ineffective, and the particles may now be inhaled by personnel in the OR[v].
Tomita et.al found that the smoke from 1g of tissue destroyed by electrosurgical methods had the mutagenic potential of smoking six unfiltered cigarettes. This table shows some of the chemicals found in surgical smoke, with those found in cigarette smoke as listed by Cancer UK and the American Cancer society highlighted for comparison.
|Free radicals||Hydrogen cyanide||Isobutene||Methane|
|Phenol||Polycyclic aromatic hydrocarbons(c)||Propene||Propylene|
(c) Carcinogen (m) Mutagen
Taken from perioperativeCPD.com (2018) Surgical Smoke; is it safe?
Hill et.al in 2012[vi], stated that OR staff were being exposed to the smoke equivalent to 27-30 cigarettes on an average day. Operating room personnel in the US are twice as likely to have time off due to a respiratory illness than the average population[vii]. Studies have demonstrated an association between smoke plumes from electrosurgery and acute headaches; eye, nose, and throat irritations; dermatitis; colic; and acute and chronic pulmonary conditions[viii]. Although few articles discussed the link between electrosurgical smoke and specific health problems, these effects may be a direct result of the smoke’s composition.
Acute exposure risks of surgical smoke for healthcare professionals
In addition, there have been infectious biological agents, specifically bacteria and viruses, reported in surgical smoke samples isolated from infected patients undergoing surgery.
Viral DNA has been identified in surgical smoke[ix] and could potentially transmit disease[x]. Along with Covid-19[xi], surgical smoke is known to carry Hepatitis, HIV, HBV, and most reported, HPV. The latter has had several reports of transmission through clinical exposure. Most recently, a paper reported two cases of HPV-positive oropharyngeal cancer in gynaecologists exposed to surgical smoke[xii].
Most surgical societies have published guidance relating to Covid-19 safety, with all making strong recommendations for the mandated use of smoke management devices[xiii].
Risk of surgical smoke exposure to the patient
The risks of surgical smoke exposure for the patient largely concern minimally invasive procedures, where all or some of the smoke is retained within the body. In open surgery, unless trapped by tissue or settling due to gravity, the smoke is released into the operating room. In contrast, in laparoscopic surgery (the most common type of MIS procedure) smoke may be retained within the abdominal cavity.
In laparoscopic surgery, smoke is first and foremost an issue for the surgeon due to the impact that it has on the quality of the operative visual field. The abdomen is a sealed environment, albeit imperfectly sealed (see below), and so surgical smoke accumulates to the point where a surgeon’s view is obscured such that continuing the procedure may be hazardous to the patient. The surgeon then has the choice to either wait for the smoke to settle (due to gravity) or to proactively intervene and remove some of the carbon dioxide gas from the abdomen and dilute the remaining gas with fresh CO2 from the insufflator. The willingness to continue operating in sub-optimal visibility and the subsequent decision to pause surgery (to wait for it to settle) or actively remove smoke from the abdomen is entirely at a surgeon’s discretion. The extent to which smoke is retained therefore depends upon the dynamic balance between the rate of smoke production, the effect of gravity on the smoke, and the [intentional] removal and replacement of carbon dioxide. No technology can claim to remove 100% of the smoke from the abdomen, because doing so would require immediate removal of all the carbon dioxide gas from the abdomen whenever smoke was produced. This is impractical because the loss of pneumoperitoneum would severely disrupt the procedure and make it impossible to complete it promptly and safely. Consequently, smoke has been retained within patients’ abdomens since the first laparoscopic procedure was performed and continues to be so today.
Despite the vast amount of literature relating to surgical smoke composition and exposure risks, there remains a striking lack of evidence of patient harm arising from smoke retention in the abdomen. Considering the chemical and infection exposure risks described above for OR personnel, it is relatively straightforward to explain. Toxicity of any given chemical is determined by the dose (the amount), duration, and frequency of exposure. Unlike for OR personnel, the patient exposure is generally single-dose, short-term and a one-off event. Whilst very few papers have reported the qualitative and quantitative composition of surgical smoke, the margin of safety for a single dose exposure is considerable[xiv] and generally acknowledged by the surgical community to be low risk.
It is also relevant to consider the regulatory approvals of smoke management devices in laparoscopic surgery. Such approvals, certainly in the USA, have generally pursued a regulatory strategy of demonstrating the rate of removal of smoke from an enclosed environment and the specification of the filter. These data provide evidence that supports the intended use of improving visualisation for the surgeon, whilst at the same time minimising release of smoke into the operating room which, de facto, reduces any long-term exposure risks. None have clinically demonstrated, or have been granted regulatory-approved claims for, any risk reduction for a patient.
Filter specifications versus real-world performance
There is now a large range of filtration-based products currently being offered for managing surgical smoke in both open and minimally invasive procedures. They range from the simple to the highly complex and differ considerably in price.
The performance of these devices and therefore their effectiveness in controlling surgical smoke remains largely unproven in real-world testing. Manufacturers typically cite the performance specification of the filter, which is a simple test result provided by the manufacturer of the filter. However, they do not specify the efficiency of capture of the smoke from the surgical site. Put simply, these devices could only capture 1% of the smoke that is created and yet still cite the filter specification of “99.9% efficient”. Real-world testing by Liu et al reported an effectiveness of 14.7% to 87.9% when using a smoke evacuation pencil[xv], demonstrating that the performance of these devices is highly variable. Finally, because they are vacuum based, it is not uncommon for the tubing to accidentally trap tissue, blocking the tubing and potentially causing unintended tissue trauma.
In terms of particle size capture of the smoke that reaches the filter, most vacuum-based smoke management systems now contain an Ultra-Low Particulate Air (“ULPA”) filter. ULPA filters are specified for effectiveness for filtering particles of 0.12µm or larger (EU standard – EN1822). If any manufacturer claims efficiency at particle sizes smaller than this, then data should be requested to evidence this specification. This is important, because 0.12µm is larger than many known viruses[xvi]. Whilst ULPA filters almost certainly trap particles smaller than this to an extent, this has not been proven using a general ULPA filter testing method.
Traditional laparoscopic smoke management systems have their limitations
Smoke management in laparoscopic surgery in one respect is simpler because the smoke is first contained within the abdominal cavity. Smoke management products can broadly be classified – in order of increasing complexity and cost – as passive filters; vacuum-based smoke filtration systems; and “advanced insufflators” that have built in smoke filtration. Almost all these now utilise a ULPA filter, and all involve the process of diluting smoke within the abdomen via a process of partial CO2 removal, filtration and replenishment, a relatively slow and inefficient process. The ongoing removal and replacement of dry, cold CO2 from the abdomen greatly increases the total patient CO2 exposure. From a practical perspective, its ongoing removal can also cause unstable pneumoperitoneum, further complicating the procedure for the surgeon. Surgeons typically elect to operate at a relatively high pressure/ high flow to tolerate this unstable pneumoperitoneum and avoid compromising patient safety.
The key variable determining the performance of filtration-based systems is the rate at which the gas exchange (and subsequent filtration) can take place. This is determined by the size of the aperture through which the gas is removed (typically the inner diameter of the trocar); the presence/absence of any instrument in the trocar; the backpressure exerted on the gas flow by the filter; and the force exerted on the gas to remove it from the abdomen. The force exerted on the gas is typically determined by the flow rate of the gas. In the case of smoke evacuators, this is created by the suction from the smoke evacuator, whereas in advanced insufflators it can be imparted by a combination of the suction and the flow rate from the insufflator. In contrast, passive filters simply utilize the pressure of the pneumoperitoneum (typically 10-15mmHg) to force CO2 out from one of the gas taps on a trocar.
Passive filters have been poorly adopted because this relatively low pressure is often insufficient to force the gas through the filter at a rate quickly enough to clear the visual field to the surgeons’ satisfaction. The presence of an instrument in the trocar provides very little space for the gas to escape. Finally, the tendency for these filters to become wet over time further increases the backpressure effect, slowing clearing to a point where the surgeon renders it a hindrance rather than a help to the procedure.
Smoke evacuators have the same limitations, but the powered suction removes the reliance on the pneumoperitoneal pressure to extract CO2 and are hence more expensive. However, due to the increased flow rate the tendency to increase pneumoperitoneum instability increases, as does the total volume of patient CO2 exposure during the procedure. Surgeons have also not welcomed the noise of a constant vacuum in the OR, although many modern smoke evacuators can be synchronized to the activation of the diathermy. The compromise of doing so is a reduction in smoke removal from the patient’s abdomen[xvii].
Finally, advanced insufflators have been developed to offer both high-flow insufflation capabilities and smoke evacuation in the same system. They are, however, both expensive to install and use in each case, with consumables costs significantly higher than standard smoke evacuation and insufflation tubing sets. High flow insufflation results in dramatically increased patient CO2 exposure, even at low pressure, potentially leading to higher incidence of tissue desiccation and damage[xviii], which is commonly believed to be one of the root causes of post-operative adhesions.
The smoke management performance of one advanced insufflator, Airseal (Conmed Corporation), has also been questioned because of the ongoing release of smoke-containing CO2 into the operating room whilst used in the mode that provides valve-free access to the abdomen, leading to recommendations by the manufacturer to supplement its use with a standard smoke evacuator[xix]. Furthermore, others have reported the entrainment of room air into the abdomen during periods of suction, leading to an increased risk of consequently embolisms [xx, xxi].
Regardless of which smoke filtration approach is used, it is important for users to recognise that none are capable of (a) eliminating patient smoke exposure[xxii]; or (b) preventing the release of surgical smoke into the operating room because of “accidental leaks” from the imperfectly sealed pneumoperitoneum[xxiii].
The Ultravision difference.
Ultravision rapidly, effortlessly, and unobtrusively minimises aerosolization of particulates during laparoscopic surgery, without the need for CO2 filtration and exchange. It was developed by a leading surgical training centre to address the three issues that are most experienced during laparoscopic surgery:
- Inefficiency, caused by the build-up of surgical smoke within the pneumoperitoneum and its impact on the operative visual field.
- The release of surgical smoke into the operating room and its impact on the health and safety of healthcare professionals.
- The excessive amounts amount of cold, dry carbon dioxide that the patient is exposed to during the procedure.
Ultravision’s mode of action – “electrostatic precipitation” – is unique in that the smoke that is created during surgery is eliminated from the operative field by rapidly suppressing its aerosolization. This contrasts with the three other means of addressing this problem. In independent tests Ultravision has proved to be 23x more effective than a representative smoke evacuator at preventing aerosols from entering the operating room[xxiv].
[i] Ulmer (https://pubmed.ncbi.nlm.nih.gov/18461735/).
[ii] Limchantra et al (https://pubmed.ncbi.nlm.nih.gov/31433468/)
[iii] Yomita et al (https://pubmed.ncbi.nlm.nih.gov/7027028/)
[iv] Brüske-Hohlfeld et al (https://pubmed.ncbi.nlm.nih.gov/19055750/)
[v] Mowbray et al (https://pubmed.ncbi.nlm.nih.gov/23605191/)
[vi] Hill et al (https://pubmed.ncbi.nlm.nih.gov/22445358/)
[viii] Okoshi et al (https://pubmed.ncbi.nlm.nih.gov/25421864/)
[ix] Christie et al (https://pubmed.ncbi.nlm.nih.gov/15918851/)
[x] Okoshi et al (https://pubmed.ncbi.nlm.nih.gov/25421864/)
[xii] Parker and Clarke 2021, HPV Positive Oropharyngeal Cancer in Two Gynaecologists Exposed to Electrosurgical Smoke Plume. Obstet Gynecol Cases Rev 8:205
[xiii] Bogani et al (https://pubmed.ncbi.nlm.nih.gov/34320592/)
[xiv] Alesi Surgical Limited, data on file
[xv] Liu N., Filipp N., Wood K.B. The utility of local smoke evacuation in reducing surgical smoke exposure in spine surgery: A prospective self-controlled study. Spine J 2020;20(2):166-173. (https://pubmed.ncbi.nlm.nih.gov/31542472/)
[xvii] Takahashi et al (https://pubmed.ncbi.nlm.nih.gov/27009080/)
[xviii] Shienny Sampurno et al, Modes of carbon dioxide delivery during laparoscopy generate distinct differences in peritoneal damage and hypoxia in a porcine model. Surgical Endoscopy, (2020), 34: 4395–4402 (https://pubmed.ncbi.nlm.nih.gov/31624943/)
[xix] ConMed Corporation, available at https://www.conmed.com/-/media/CONMED/Documents/AS%20Education/MC20191591_Insufflation_Recommendations.pdf
[xx] Ciara R Huntington et al, Safety first: significant risk of air embolism in laparoscopic gasketless insufflation systems. Surg Endoscopy, (2019), 33(12):3964-3969
[xxi] R P Weenink et al, The AirSeal® insufflation device can entrain room air during routine operation. Tech Coloproctol, (2020), 24(10):1077-1082
[xxii] Takahashi et al (https://pubmed.ncbi.nlm.nih.gov/27009080/)
[xxiii] Dalli et al (https://pubmed.ncbi.nlm.nih.gov/32691961/)
[xxiv] Buggisch et al (https://pubmed.ncbi.nlm.nih.gov/32891798/)