Smoke evacuation in the age of COVID-19

July 2, 2020

Though theoretical, the threat of aerosolized viral particles places health care providers at risk. Certain safety measures can be taken.

The coronavirus pandemic presents many challenges to gynecologists, particularly in surgery. Although efforts have been made to either limit or appropriately triage non-emergent surgery during the COVID-19 pandemic, emergent procedures, such as treatment for a ruptured ectopic pregnancy, must still be performed.

Contemporary data on COVID-19 transmission risk during surgery are limited and many have questioned the safety of laparoscopic surgery for fear of aerosolized viral particles in surgical plume putting healthcare providers at risk.

The worry is that use of pneumoperitoneum and electrosurgery, both of which are integral parts of laparoscopy, may enhance this risk. We aim to discuss this theoretical risk and what safety measures can be taken to provide a safer work environment for vital healthcare workers.

Aerosolization of viruses

The virus that causes the infection commonly referred to as COVID-19 is a novel respiratory pathogen (SARS-CoV-2), which spreads via droplets. The approximate size of COVID-19 virions range from 50 to 200 nm; N-95 masks filters, with 95% efficiency, against 300 nm particles.1,2

However, viral particles can also spread with aerosolization procedures such as intubation. SARS-CoV-2 has also been detected in blood and stool specimens, but the infectivity of these extrapulmonary specimens is unknown.3,4 Since the viral RNA has been found in stool, it is suggested that the virus could also then be found within the gastrointestinal mucosa.5

Some have theorized that pneumoperitoneum in laparoscopy can create a stagnant heated volume of gas in the abdominal cavity, which could allow for concentrated aerosolization of the virus. Release of pneumoperitoneum from trocar valves during instrument exchange, venting, or removal could allow for virus transmission.

Another concern stems from electrosurgical plume; when activated in laparoscopy, electrosurgical devices could release aerosolized debris into the abdomen. Both of these post a potential risk of viral transmission.6 

Most of our understanding of viral aerosolization comes from the study of other viral diseases, mainly hepatitis B (HBV) and human papillomavirus (HPV), although admittedly, this issue is not well-studied in laparoscopy.

One study demonstrated that HBV was detected from the surgical plume of infected patients.7

However, no subsequent studies were performed to determine if those HBV particles had viral infectivity or were capable of transmitting the disease. Several studies found that although aerosolized HPV DNA couldbe detected in surgical plume, there was no evidence that these particles could develop into an active infection or be transmitted to the surgical team.8-11

Furthermore, one of these studies demonstrated that with use of smoke evacuation systems and proper personal protective equipment (PPE), there was no evidence of dispersion of viral DNA onto the skin of the surgeon.9 Although the route of transmission for HBV and HPV is different than for SARS-CoV-2, there are no data to support viral transmission by laparoscopy.

To mitigate the theorized risk of viral transmission during laparoscopy, many believe that using a closed-circuit surgical system for smoke evacuation prevents room contamination with aerosolized particles and minimizes the potential risk for transmission.

Several different insufflation systems exist, some of which also include smoke evacuation components. Independent laparoscopic smoke evacuator systems also exist.

One system that has been suggested for use during the COVID-19 pandemic is the AirSeal (Conmed, Utica, NY). This device has valve-less access ports, which minimizes any loss of pneumoperitoneum during instrument exchanges.

The trilumen flow tube filters particles while simultaneously allowing carbon dioxide inflow and outflow. AirSeal also has a special mode that allows for smoke evacuation and more liberal circulation of pneumoperitoneum, decreasing possible concentration of aerosolized virus. The PneumoClear (Stryker, Kalamazoo, MI) is another integrated insufflator but uses traditional trocars with valves.

The PneumoClear also has an added feature of de-sufflating the abdomen at the end of the case, which removes the need for release of any pneumoperitoneum. For both of these systems, ultra-low particle (ULPA) filters can be used, if available, to help filter viral particles that have been aerosolized during surgery.

In conjunction with tightly fitting laparoscopic ports, a smoke evacuation and filtration system can be used to minimize release of potential virus in the operating room.

When smoke evacuation systems are not available, direct wall suction can be used to evacuate plume through a laparoscopic trocar. Wall suction devices can also be attached to the same ULPA filters used for endotracheal tubes, although this method does not guarantee the high filtration efficiency of manufactured smoke evacuation devices.12

In addition, minimizing use of energy devices during procedures whenever possible may decrease aerosolization of particles. Final risk reduction methods may include reducing the abdominal pressure of pneumoperitoneum required for the operation.

Regardless, it is extremely important that all individuals in the operating room wear proper personal protective equipment (PPE), including N95 respirators.

Recognition of Risk

The aforementioned risks and possible solutions have been recognized by surgical societies worldwide. A joint statement issued by the American Association of Gynecologic Laparoscopists (AAGL) with multiple other gynecology profressional societies acknowledged that steps must be taken for the safety our patients and our healthcare providers.

Minimally invasive techniques are the preferred method if urgent surgery is required. Data about the risk of transmission of COVID-19 via surgical plume is limited. Proper PPE is always recommended.13

Conclusion

There is only a theoretical risk of transmission of viral particles from the abdomen of a COVID-19-infected individual. However, until definitive data are available, it seems prudent to use simple strategies to help mitigate these risks.

These strategies include closed-circulation smoke evacuation, PPE, minimizing use of energy devices, low pneumoperitoneum pressures, and de-sufflating the abdomen using a smoke evacuation device or suction substitute with ULPA filters, if available.

With the paucity of data, more research needs to be conducted around COVID-19 and laparoscopy.

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Drs. Rahman, Klebanoff and Moawad report no conflicts.

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References

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