Battle of the Gases: How Air and Nitrous Oxide Affect Endotracheal Tube Cuff Pressure During General Anesthesia.

Abstract

Background Endotracheal tube (ETT) cuff pressure changes during general anesthesia. Endotracheal cuff pressure ideally should be maintained between 20 and 30 cm of H2O. Cuff pressure of less than 25 cm of H2O increases the chances of aspiration while pressure of more than 40 cm of H2O causes tracheal mucosa damage. The study aimed to monitor and compare variations of endotracheal cuff pressure during general anesthesia with oxygen-air or oxygen-nitrous oxide. Methods This prospective, randomized, double-blinded, observational study was conducted on 40 patients. After approval from the institutional ethics subcommittee, 40 patients of either gender, aged 18-60 years, belonging to ASA grades I and II, who were undergoing elective surgery under general anesthesia, were enrolled in this study. The patients were randomly divided into two groups, with 20 in each group. In Group A, oxygen-air and Group N, oxygen-nitrous oxide was used as a gaseous mixture in general anesthesia with ETT. The ETT cuff pressure was recorded with the help of a cuff manometer at intervals of five, 10, 20, 30, 40, 50, 60, 70, 80, and 90 minutes after intubation. If pressure was more than 40 cm of H2O, it was reduced to 25-30 cm of H2O. Data were collected and analyzed using methods described in Primer of Biostatistics by Stanton A. Glantz. Quantitative data were analyzed using the Student's t-test. Qualitative data were analyzed using the chi-square test. Results An increase in cuff pressure was noted more in Group N as compared to Group A. The pressure in the endotracheal cuff started to gradually increase after 30-40 minutes in Group N after intubation, while in Group A, there was no significant increase. The average number of times the cuff deflated was 0.2 ± 0.41 in Group A and 1.55 ± 0.51 in Group N, which was highly significant. Conclusion Changes in endotracheal cuff pressure were observed when using different gas mixtures for inflation. Specifically, cuff pressure increased with oxygen and nitrous oxide compared to oxygen with air. This suggests that anesthetic gas composition can impact cuff pressure, potentially affecting tracheal mucosal perfusion and patient safety. Therefore, regular monitoring and adjustment of cuff pressure is crucial, especially when using nitrous oxide, to prevent complications and ensure optimal patient care.