Solving the problems of gas leakage at laparoscopy

The sound of surgery-development of an acoustic trocar system enabling laparoscopic sound analysis

PURPOSE

Acoustic information can contain viable information in medicine and specifically in surgery. While laparoscopy depends mainly on visual information, our goal is to develop the means to capture and process acoustic information during laparoscopic surgery.

METHODS

To achieve this, we iteratively developed three prototypes that will overcome the abdominal wall as a sound barrier and can be used with standard trocars. We evaluated them in terms of clinical applicability and sound transmission quality. Furthermore, the applicability of each prototype for sound classification based on machine learning was evaluated.

RESULTS

Our developed prototypes for recording airborne sound from the intraperitoneal cavity represent a promising solution suitable for real-world clinical usage All three prototypes fulfill our set requirements in terms of clinical applicability (i.e., air-tightness, invasiveness, sterility) and show promising results regarding their acoustic characteristics and the associated results on ML-based sound classification.

CONCLUSION

In summary, our prototypes for capturing acoustic information during laparoscopic surgeries integrate seamlessly with existing procedures and have the potential to augment the surgeon's perception. This advancement could change how surgeons interact with and understand the surgical field.

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.

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.

Characterisation of trocar associated gas leaks during laparoscopic surgery

BACKGROUND

During laparoscopy, the abdominal cavity is insufflated with carbon dioxide (CO₂) that could become contaminated with viruses and surgical smoke. Medical staff is potentially exposed when this gas leaks into the operating room through the instruments and past trocar valves. No detailed studies currently exist that have quantified these leakage pathways. Therefore, the goal of this study was to quantify the gas leakages through trocars and instruments, during minimally invasive procedures.

METHODS

A model of the surgical environment was created, consisting of a rigid container with an interface for airtight clamping of laparoscopic equipment such as trocars and surgical instruments. The model was insufflated to 15 mm Hg using a pressure generator and a pneumotachograph measured the equipment gas leak. A protocol of several use cases was designed to simulate the motions and forces the surgeon exerts on the trocar during surgery.

RESULTS

Twenty-three individual trocars and twenty-six laparoscopic instruments were measured for leakage under the different conditions of the protocol. Trocar leakages varied between 0 L/min and more than 30 L/min, the instruments revealed a range of leakages between 0 L/min and 5.5 L/min. The results showed that leakage performance varied widely between trocars and instruments and that the performance and location of the valves influenced trocar leakage.

CONCLUSIONS

We propose trocar redesigns to overcome specific causes of gas leaks. Moreover, an international testing standard for CO₂ leakage for all new trocars and instruments is needed so surgical teams can avoid this potential health hazard when selecting new equipment.

Free and Forced Convective Flow in Pleural Fluid with Effect of Injection between Different Permeable Regions

Pleural effusion is an interruption of a pleural cavity in the lung wall. The lung and chest wall reversal process leads to pleural fluid aggregation in the pleural space. The parietal lymphatic expansion occurs because of increased pleural fluid. This model has been developed to obtain new results of respiratory tract infections, and also investigated the reaction of injection on an unstable free and forced convection flow of visceral pleural fluid transports in two different vertical porous regions. Finally, the model gives an impact of COVID-19 in the human respiratory tract, as it helps to anticipate early summary of establishing current pandemic infection. Results are computed analytically and plotted graphically for various physical parameters. The main highlights of this paper are mixed convection has been investigated mathematically in porous media, the effect of temperature and velocity field of pleural fluid was analyzed based on human lung mechanism, heat exchange associates with mucus layer and pleural fluid layer corresponding to thermal radiation and heat absorption, contribution of injection parameter over the region’s mucus and pleural phase, it has shown high sensitivity flow in diagnosis of COVID-19 due to pleural effusion.

Aerosols, airflow, and airspace contamination during laparoscopy

Laparoscopic surgery has been undermined throughout the COVID-19 pandemic by concerns that it may generate an infectious risk to the operating team through aerosolization of peritoneal particles. There is anyway a need for increased awareness and understanding of the occupational hazard for surgical teams regarding unfiltered escape of pollutants generated by surgical smoke and other microbials. Here, the aerosol-generating nature of this access modality was confirmed through repeatable real-time methodology both qualitatively and quantitively to inform best practice and additional engineering solutions to optimize the operating room environment.

Acute appendicitis during the COVID-19 lockdown: never waste a crisis!

1. Whilst the number of Covid-19 cases increases, fewer patients present with appendicitis to the emergency department, and those who do, present with more advanced disease. 2. These findings are consistent with the hypothesis of a pre-hospital selection, with high rates of successful resolution of uncomplicated appendicitis following patients self-medication with antibiotics at home. 3. Patients admitted with suspected appendicitis during the pandemic are more likely to undergo preoperative imaging, which possibly explains the fall in negative appendectomy rate, especially in the UK.

Bioaerosols during transanal minimally invasive surgery

BACKGROUND

There is concern regarding bioaerosols from patients having procedures impacting surgical team safety. As pathogens and pollutants have been found in surgical smoke, we examined the potential for aerosol escape during transanal minimally invasive surgery (TAMIS) which may be particularly important given the presence of faecal contamination in the operative workspace and the specifics of its access platforms.

METHODS

Both qualitative (thermographic imaging) and quantificative (particle counting) methods were used to assess for aerosol release during TAMIS in comparison to laparoscopic operations of similar duration and equipment both at times of surgical dissection and without. TAMIS was performed using a Gelport Path Device (Applied Medical) and Airseal insufflation with valveless trocar (ConMed).

RESULTS

Significant carbon dioxide (CO₂) escapes during TAMIS carrying with it considerable numbers of particles. In general, particle counts were low prior to tissue dissection phases of the operation but increased substantially (25 × 10⁶/m³ or over 40× background counts) during hook cautery dissection. The majority of particles were in the 0.3-0.5 micron range (where counts were increased relative to background between 42× and 65) with the highest relative increase versus background in the 0.5-1.0 micron range. Particle counts < 5 were substantially greater during the TAMIS procedure versus laparoscopic procedures (a laparoscopic-assisted parastomal hernia repair and laparoscopic cholecystectomy) employing similar tools.

CONCLUSIONS

Considerable amounts of particle-rich aerosols escape during TAMIS procedures. Although pathogens are not proven to definitely spread to healthcare staff by such material nebulisation, N95/FFP2 masks, at a minimum, seem prudent while other methods evolve to eliminate this risk.