Current Evidence for Minimally Invasive Surgery during the COVID-19 Pandemic and Risk Mitigation Strategies: A narrative review - Annals of Surgery
Aim: Summarise the evidence on the current risks (aerosolization etc.) of laparoscopic surgery during the COVID-19 epidemic.
- Outside of the lung and oropharynx, the ACE2 receptor (which Sars-CoV-2 targets) can be found in colonocytes, gastric, duodenal, jejunal, ileal, and rectal endothelial cells, as well as in smooth muscle cells of the muscularis mucosae, muscularis propria, and vasculature of the gastrointestinal tract.
- Viral RNA can be detected in stool, the clinical significance of which remains unknown. There is speculation of oro-fecal transmission.
- Most studies are unable to detect RNA in urine or blood (except for very severe cases)
- This needs to be a point of consideration when managing patients with a perforated viscus and COVID-19 to ensure appropriate precautions are employed, including complete personal protective equipment (PPE) for healthcare providers, patient isolation, and negative pressure rooms where available
Minimizing Resource Utilization by Enhancing Recovery and time to Discharge
- Several general surgical procedures (E.g. appendectomy, cholecystectomy, perforated viscous repair) are known to be more effective (shorter surgical time, faster discharge, fewer complications, less analgesia, earlier intake, fewer wound infections etc.) with minimally invasive techniques.
Risk of Transmission and Mitigation Strategies
- Certain surgical procedures, both laparoscopic and open in approach, have been labelled as aerosol generating medical procedures. Aerosolization can result from dissection with electrosurgical instruments, as the heat of such devices results in a plume of surgical smoke.
- Although the risk of viral infection of the surgeon is well-documented in open surgery, no such literature exists in laparoscopic surgery.
- However, studies comparing the quantity and quality of surgical smoke produced by various instruments found that the main determinant of aerosolization was the instrument used, supporting the notion that the surgical plumes are produced in both laparoscopic and open surgery
- Also the additional risk of pneumoperitoneum in laparoscopic surgery compared to open surgery remains controversial
- In general, a number of strategies are employed in operating rooms to mitigate these risks including negative-pressure ventilation (preventing cross-contamination between rooms), minimizing time and exposure during intubation, using surgical masks, as well as smoke evacuation systems.
- Some concern has been raised regarding surgical and N95 masks and the ability to prevent the inhalation of particles in surgical smoke, given that N95 masks filter particles larger than 0.3 µm while generated particle size ranges from 0.07 to 0.42
Creation of a closed circuit and viral filter properties
- In open surgery, smoke evacuation systems are used to control surgical plume, typically composed of suction devices attached to the electrosurgical source the efficacy of which is variable (44-99%)
- Laparoscopic procedures have the ability to create a more regulated closed environment that allows all inflow and outflow of air to be controlled. Proper smoke evacuation is essential (ULPA filtration).
Insufflational pressures and flow: managing the pressure gradient
- Early in vivo studies have suggested that higher pressure environments and longer procedure times could contribute to an increase in rates of aerosolization
- There is level one data available on the feasibility of low-pressure insufflation states, facilitated by deep neuromuscular blockade (8-10 mmHG)
- Several maneuvers that can help to minimize viral exposure
- Regarding trocar insertion, minimizing incision length and avoiding any significant lateral movements on introduction is recommended
- The removal of trocars should be performed once the abdomen is desufflated
- It is important to remain cognizant of the minimum instrument size capable of maintaining a seal within each type of trocar.
- If a seal at a valve is felt to have been compromised, closing the port by placing a finger over the opening, ceasing insufflation, and desufflating the abdomen is recommended
- It is recommended to avoid vessel-sealing devices, ultrasonic devices, and harmonic scalpels as these may increase aerosolization of viral particles.
- Outflow during desufflation should be occur through the trocar in the least dependent position (typically an epigastric port).
- The use of intraperitoneal gauze should be avoided
- Leaving intraperitoneal drains should be reconsidered
Terminating a procedure
- Minimize personnel in OR to save PPE.
- When the procedure is completed and specimens are secured for subsequent removal, we recommend closing the insufflation port while keeping the smoke evacuation port open.
- It is also of crucial importance to notify your anesthesia colleagues to prevent the patient from emerging from general anesthesia prematurely, which may inadvertently result in increased intra-abdominal pressures, forcing air out of the abdomen.
- When decompressed (do not use suction device!), ensure the ports are removed slowly and carefully. All reusable instruments, even in SARS-Cov-2 negative patients, should be treated as potentially contaminated.
- At the completion of the procedure, it is also crucial to ensure enough time has elapsed of the negative pressure environment for the air within the room to have been recycled prior to leaving the room.