Aerosols, airflow, and airspace contamination during laparoscopy

Development of an effective simulation model for evaluating smoke leakage during laparoscopic surgery

The leakage of surgical gas and smoke from the peritoneum during laparoscopy may release noxious aerosols, including potential carcinogens, viruses and other contaminants, into the operating theatre, especially into the breathing zone of the surgical team. Reliable and realistic models and methods that develop and detect surgical smoke in simulated settings are necessary to effectively test devices and strategies intended to reduce such leaks. Here, we report a novel high-fidelity laparoscopic smoke model with innovative imaging methods applicable to the theatre setting, followed by an assessment of the usefulness of commercial laparoscopic trocars and smoke evacuation methods in mitigating gas leaks. Various smoke production methods (including tissue cautery and industrial smoke machinery) and detection methods (including schlieren imaging, laser videography, intraperitoneal video recording, and an aerosol detector) were tested, with the smoke machine model proving the most reproducible. Schlieren imaging, laser videography and intraperitoneal video recording were all effective methods of surgical smoke quantification. Following model establishment, laparoscopic trocars (VersaOne TM , Medtronic, Ireland) and smoke evacuation systems (EVA15 smart insufflator and evacuator, Palliare, PlumePort Activ® Smoke Filtration Device, Conmed and Valleylab TM Smoke Evacuation System, Medtronic) were examined in a standardized way with performance assessment by three surgeons independently using a boutique scoring system. The EVA15 outperformed other smoke systems in clearing surgical smoke from the operative field and in reducing trocar leaks during instrumentation. This method of simulated surgical smoke production and assessment can benchmark other laparoscopic equipment regarding smoke management strategies in a similar fashion.

Influence of SARS-CoV2 Pandemic on Colorectal Cancer Diagnosis, Presentation, and Surgical Management in a Tertiary Center: A Retrospective Study

Background: Oncological surgery during the COVID-19 pandemic was performed only in carefully selected cases, due to variation in the allocation of resources. The purpose of this study was to highlight the impact of the pandemic lockdown on the presentation, diagnosis, and surgical management of colorectal cancers as well as the post-pandemic changes in this area. Material and methods: This single center, retrospective comparative study contained 1687 patients, divided into three groups with equal time frames of two years, consisting of a pre-pandemic, pandemic, and post-pandemic period, in which preoperative and perioperative as well as postoperative parameters were compared. Results: Statistically significant differences regarding environment, type of admission, and ASA score, as well as a more advanced tumoral stage, increased number of important postoperative complications, and a lower minimally invasive surgical approach, were highlighted within the pandemic group. Statistically significant differences regarding emergency diagnosis as well as late diagnosis were highlighted. There were no significant differences regarding the tumor location, postoperative 30-day mortality, or hospitalization duration. Conclusions: COVID-19 significantly impacted the surgical timing in colorectal cancer, as well as addressability for the rural population, with a marked decrease in elective cases as well as an increased number of cases diagnosed in an emergency setting, with locally advanced tumors. However, no significant changes in postoperative mortality or hospitalization duration were highlighted. In addition, most of the changes highlighted were reverted in the post-pandemic period. Further studies are required to observe the long-term effects in terms of morbidity and mortality, regarding the delay of diagnosis and oncological treatment.

Surgical smoke and its components, effects, and mitigation: a contemporary review

Energy-based surgical instruments produce surgical smoke, which contains harmful byproducts, such as polycyclic aromatic hydrocarbons, volatile organic compounds, particulate matter, and viable microorganisms. The research setting has shifted from the laboratory to the operating room. However, significant heterogeneity in the methods of detection and placement of samplers, diversity in the tissue operated on, and types of surgeries tested has resulted in variability in detected levels and composition of surgical smoke. State regulation limiting surgical smoke exposure through local evacuators is expanding but has yet to reach the national regulatory level. However, most studies have not shown levels above standard established limits but relatively short bursts of high concentrations of these harmful by-products. This review highlights the limitations of the current research and unsupported conclusions while also suggesting further areas of interest that need more focus to improve Occupational Safety and Health Administration guidelines.

Characterisation and mitigation of gas leaks at laparoscopy: an international prospective, multi-center cohort clinical trial

INTRODUCTION

Gas leaks polluting the operating room are common in laparoscopy. Studies defining methods for sensitive leak characterisation and mechanical mitigation in real world settings are, however, lacking.

METHODS

Mobile optical gas imagers (both a miniaturised Schlieren system and sensitive tripod-mounted near-infrared carbon dioxide camera (GF343, FLIR)) prospectively defined trocar-related gas leaks occurring either spontaneously or with instrumentation during planned laparoscopic surgery at three hospitals. A boutique Matlab-based analyser using sequential frame subtraction categorised leaks (class 0-no observable leak; class 1-marginally detectable leak; class 2-short-lived plume; class 3-energetic, turbulent jet). Concurrently, the usefulness of a novel vacuum-ring device (LeakTrap™, Palliare, Ireland) designed as a universal adjunct for existing standard laparoscopic ports at both abdominal wall and port valve level was determined similarly in a phase I/11 clinical trial along with the device's useability through procedural observation and surgeon questionnaire.

RESULTS

With ethical and regulatory approval, 40 typical patients (mean age 58.6 years, 20 males) undergoing planned laparoscopic cholecystectomy (n = 36) and hernia repair (n = 4) were studied comprising both control (n = 20) and intervention (n = 20) cohorts. Dual optical gas imaging was successfully performed across all procedures with minimal impact on procedural flow. In total, 1643 trocar instrumentations were examined, 819 in the control group (mean 41 trocar instrumentations/procedure) and 824 in the intervention group (mean 41.2 trocar instrumentations/procedure). Gas leaks were detected during 948(62.6%) visualised trocar instrumentations (in 129-7.8%-the imaging was obscured). 14.8% (110/742) and 60% (445/742) of leaks in control patients were class 0 and 3, respectively, versus 59.1% (456/770) and 8.7% (67/772) in the interventional group (class 3 v non-class 3, p < 0.0001, χ2). The Leaktrap proved surgically acceptable without significant workflow disruption.

CONCLUSION

Laparoscopic gas leaks can be sensitively detected and consistently, effectively mitigated using straightforward available-now technology with most impact on the commonest, highest energy instrument exchange leaks.

Understanding surgical smoke in laparoscopy through Lagrangian Coherent Structures

In laparoscopic surgery, one of the main byproducts is the gaseous particles, called surgical smoke, which is found hazardous for both the patient and the operating room staff due to their chemical composition, and this implies a need for its effective elimination. The dynamics of surgical smoke are monitored by the underlying flow inside the abdomen and the hidden Lagrangian Coherent Structures (LCSs) present therein. In this article, for an insufflated abdomen domain, we analyse the velocity field, obtained from a computational fluid dynamics model, first, by calculating the flow rates for the outlets and then by identifying the patterns which are responsible for the transportation, mixing and accumulation of the material particles in the flow. From the finite time Lyapunov exponent (FTLE) field calculated for different cross-sections of the domain, we show that these material curves are dependent on the angle, positions and number of the outlets, and the inlet. The ridges of the backward FTLE field reveal the regions of vortex formation, and the maximum accumulation, details which can inform the effective placement of the instruments for efficient removal of the surgical smoke.

The influence of prolonged instrument manipulation on gas leakage through trocars

BACKGROUND

During laparoscopic surgery, CO2 insufflation gas could leak from the intra-abdominal cavity into the operating theater. Medical staff could therefore be exposed to hazardous substances present in leaked gas. Although previous studies have shown that leakage through trocars is a contributing factor, trocar performance over longer periods remains unclear. This study investigates the influence of prolonged instrument manipulation on gas leakage through trocars.

METHODS

Twenty-five trocars with diameters ranging from 10 to 15 mm were included in the study. An experimental model was developed to facilitate instrument manipulation in a trocar under loading. The trocar was mounted to a custom airtight container insufflated with CO2 to a pressure of 15 mmHg, similar to clinical practice. A linear stage was used for prolonged instrument manipulation. At the same time, a fixed load was applied radially to the trocar cannula to mimic the reaction force of the abdominal wall. Gas leakage was measured before, after, and during instrument manipulation.

RESULTS

After instrument manipulation, leakage rates per trocar varied between 0.0 and 5.58 L/min. No large differences were found between leakage rates before and after prolonged manipulation in static and dynamic measurements. However, the prolonged instrument manipulation did cause visible damage to two trocars and revealed unintended leakage pathways in others that can be related to production flaws.

CONCLUSION

Prolonged instrument manipulation did not increase gas leakage rates through trocars, despite damage to some individual trocars. Nevertheless, gas leakage through trocars occurs and is caused by different trocar-specific mechanisms and design issues.

Impact of intra-abdominal insufflation pressure on gas leakage occurring during laparoscopy

INTRODUCTION

The advent of the COVID-19 pandemic led to recommendations aimed at minimizing the risk of gas leaks at laparoscopy. As this has continuing relevance including regarding operating room pollution, we empirically quantified carbon dioxide (CO2) leak jet velocity (important for particle propulsion) occurring with different instruments inserted into differing trocars repeated across a range of intra-abdominal pressures (IAPs) and modern insufflators in an experimental model.

METHOD

Laparoscopic gas plume leak velocity (metres/second) was computationally enumerated from schlieren optical flow videography on a porcine cadaveric laparoscopic model with IAPs of 4-5, 7-8, 12-15 and 24-25 mmHg (repeated with 5 different insufflators) during simulated operative use of laparoscopic clip appliers, scissors, energy device, camera and staplers as well as Veres needle (positive control) and trocar obturator (negative control) in fresh 5 mm and 12 mm ports.

RESULTS

Close-fitting solid instruments (i.e. cameras and obturators) demonstrated slower gas leak velocities in both the 5 mm and 12 mm ports (p = 0.02 and less than 0.001) when compared to slimmer instruments, however, hollow instrument designs were seen to defy this pattern with the endoscopic linear stapler visibly inducing multiple rapid jests even when compared to similarly sized clip appliers (p = 0.03). However, on a per device basis the operating instrumentation displayed plume speeds which did not vary significantly when challenged with varying post size, IAP and a range of insufflators.

CONCLUSION

In general, surgeon's selection of instrument, port or pressure does not usefully mitigate trocar CO2 leak velocity. Instead better trocar design is needed, helped by a fuller understanding of trocar valve mechanics via computational fluid dynamics informed by relevant surgical modelling.