Gas Pressure From the Endoscope: An Unexplored Contributor to Morbidity and Mortality?

Background It has been shown that the incidence of venous air embolism and venous carbon dioxide (CO₂) embolism is high during endoscopic retrograde cholangiopancreatography (ERCP). We examined insufflating gas flow and maximum pressure produced by three types of commonly used endoscopes because we could not readily locate technical data for endoscope gas flow and maximum emitted pressure in the manufacturer's manuals. Methods We tested the Olympus GIF-Q180 used for esophagogastroduodenoscopy, the CF-Q180 used for colonoscopy, and the TJF-Q180 used for ERCP (Olympus America Inc., Center Valley, Pennsylvania). Under three different clinical gas insufflation scenarios, we measured in vitro maximum gas pressure transduced from a closed space created at the endoscope tip in a worst-case scenario analysis. Results We showed that it is readily possible to generate a pressure (>5-30 times normal central venous pressure) in the air space at the tip of all three endoscopes when insufflation is activated and the gas egress is limited. Conclusions These findings shed additional light on in vivo occurrences of gas embolism during gastrointestinal endoscopy. We postulate that in addition to using exclusively CO₂ as the insufflating gas, the risk of gas embolism can be further diminished by regulating insufflating gas pressure at the tip of endoscopes.

Effects of different intraabdominal pressures on internal jugular vein, liver and kidney functions in obese patients undergoing laparoscopic sleeve gastrectomy

OBJECTIVE

The aim of this study was to investigate whether there was a difference in laparoscopic sleeve gastrectomy (LSG) performed with either 10 mmHg or 13 mmHg intraabdominal pressures. Effects of these pressures on the internal jugular vein (IJV) diameter and flow along with the liver and kidney function tests were evaluated.

MATERIALS AND METHODS

The patients were divided into two groups with respect to the intraabdominal pressure performed during LSG (either 10 or 13 mmHg). The patients' age, comorbidities, surgical history, height, weight, body mass index, family history, duration of surgery, length of hospital stay, serum liver and kidney function tests (Urea, creatinine, Aspartate transaminase, Alanine transaminase, Gamma-glutamyltransferase, Alkaline phosphatase, bilirubin) and the right IJV diameter and flow measured by Duplex ultrasound before intubation (t1), 10 min after insufflation (t2), and at the end of insufflation (t3) were recorded.

RESULTS

Preoperative and postoperative kidney and liver function values of the patients in both groups were within the reference range. In both groups, there was a significant decrease in the IJV diameter and flow measurement values at t2 compared to t1, and a significant increase was observed at t3 compared to t2 (p < 0.05). The mean IJV diameter and flow were significantly higher in the 10 mmHg pressure group compared to the 13 mmHg group (p < 0.05).

CONCLUSION

Neither of the peak pressures performed intraabdominal during LSG caused an adverse effect on liver or kidney functions. Our study emphasizes that low insufflation pressure does not have an advantage in terms of liver and kidney functions. But laparoscopic sleeve gastrectomy with low intra-abdominal pressure may be beneficial especially in patients who require central vein catheterization during the operation. We consider that LSG performed with CO₂ pneumoperitoneum at 10 mmHg is a safe, effective and feasible method that can facilitate the insertion of the intraoperative central venous catheter due to lesser charges in the IJV diameter and flow compared to the standard technique.

Back to Basics: Minimally Invasive Surgery

In the past 20 to 30 years, minimally invasive surgery (MIS) has become commonplace in almost all surgical specialties. The needs of the perioperative team and patients are different during MIS than during traditional open surgery. The equipment and instrumentation required to perform MIS are extensive and continue to evolve as new techniques are developed. As advances in MIS occur and more procedures are completed using this method, some surgeons are conducting research studies related to the efficacy of certain longstanding MIS protocols. Perioperative nurses are challenged to stay current on the available technology and results of research studies so that they can provide safe patient care. This Back to Basics article will provide basic strategies for perioperative nurses to ensure successful MIS outcomes for patients.

Endotracheal Tube Seal and Suction Performance in a Novel Biorealistic Tracheal Model

BACKGROUND

Endotracheal tube (ETT) cuffs create a seal to protect against secretion entry to the lungs. Cuff inflation currently is recommended at 20-30 cm H2O pressure. ETT designs have variable seal performance in bench studies using rigid tracheal models lacking the dynamic characteristics of the human trachea. We compared ETT designs within a new, biorealistic tracheal model to assess cuff and suction performance in the setting of a compliant trachea.

METHODS

Three ETT designs (Mallinckrodt Hi-Lo, KimVent Microcuff, and Sheridan/HVT) were tested for performance by simulant leakage below the cuff and air leakage (measured as return tidal volume ≥ 80% delivered) over a range of cuff (5-25 cm H2O) and end-expiratory pressure (PEEP 0-15 cm H2O). Subglottic suction channel performance was tested in 2 ETTs (TaperGuard Evac [Covidien] and ISIS HVT [Teleflex]) as time to evacuate the simulant.

RESULTS

All ETT cuffs provided effective seals at an inflation pressure of 12 cm H2O when PEEP was ≤ 5 cm H2O. The Microcuff ETT sealed at the lowest pressure of 6 cm H2O, whereas the Sheridan/HVT cuff sealed at 12 cm H2O (P = .01). With a PEEP of 15 cm H2O, a reciprocal increase in air leak occurred, requiring a cuff inflation up to 22 cm H2O to maintain a return tidal volume at ≥ 80% delivered. Suction channel performance improved in the lateral position compared with supine for both ETT designs during continuous 15 mm Hg suction pressure (P = .001).

CONCLUSIONS

Within a novel model with normal trachea compliance, we found all ETT designs tested to seal at lower than current recommended cuff pressures.