Gas leakages from gastrointestinal endoscopy system-its visualization and semi-quantification utilizing schlieren optical system in the swine models

BACKGROUND AND AIMS

With the global epidemic of SARS-CoV-2, there has been a growing concern regarding the risk of aerosol exposure to healthcare workers and patients during medical/surgical interventions. The Schlieren device is capable of visualizing fine gas-flows by using refractive index differences in the medium. We aimed to reveal the existence of gas leakage from gastro-intestinal endoscopy system by utilizing Schlieren device and to clarify the factors which relates to the amount of gas leakage.

METHODS

The experiments were performed on the excised swine stomach while maintaining a constant pressure environment in the stomach. The System Schlieren (SS100,KatoKoken) was used to visualize possible gas leakages from forceps plugs of endoscopy. We attempted to semi-quantify the leakage by referring to the image of the gas from the forceps plug and by measuring the initial velocity and diffusion area of the leakage.

RESULTS

Regardless of the type of forceps plugs, a certain amount of leakage was detected during both insertion and removal of forceps. The initial velocity and the diffusion area of the leakage increased with the increase in intragastric pressure. Semi-quantitative comparison showed that there was a difference in the amount of gas leakage among various forceps plugs. Furthermore, the amount of gas leakage was significantly greater in the forceps plugs that were used repeatedly.

CONCLUSION

It was possible to visualize gas leakages from the gastrointestinal endoscope system using the Schlieren optical device. Avoiding too high intragastric pressure and not using deteriorated plugs may reduce the risk of aerosol exposure.

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.

Risk analysis of gas leakage in gas pressure reduction station and its consequences: A case study for Zahedan

Industrial accidents have increased the importance of dealing with the risks of toxic exposure, fire and explosion. Despite the measures taken in the chemical industry to prevent accidents, the accidents occur often due to human error or process faults during repairs. Although several studies have been conducted on the accidents in the process industry, no research has modeled the risks caused by the leakage of toxic substances in the gas pressure reduction station. The consequences of gas leak and fire in Zahedan's gas pressure reduction station were investigated in Iran. This research aims to determine the safe range of the station and observe the safety measures required for the gas pressure reduction station in Zahedan. For modelling gas leak and fire, the ALOHA software was used to display the threat zone. In this research, with respect to the environmental data, the desired scenario was modeled. The results, based on two scenarios of gas leak and fire in both hot and cold seasons, indicate that the gas leak scenario in hot seasons and the fire scenario in cold seasons influence a larger region.

Interruption in the supply of breathing gas during general anesthesia due to malposition of the vaporizer -A case report-

We report a case of interruption in the supply of breathing gas during general anesthesia caused by malposition of the Drager Vapor 2000® vaporizer, which was accidentally tilted and lifted off the Selectatec manifold of the anesthesia machine. Because the patient was an 1-month-old infant, we couldn't check if he had experienced awareness with recall. We emphasize the importance of checking the anesthetic vaporizer after mounting it on the back bar of the anesthesia machine.