Automated Control of Endotracheal Tube Cuff Pressure during Simulated Flight

Successful mechanical ventilation requires that the airway be controlled by an endotracheal tube ETT with an inflatable cuff to seal the airway. Aeromedical evacuation represents a unique challenge in which to manage ETT cuffs. We evaluated three methods of automatic ETT cuff pressure adjustment during changes in altitude in an altitude chamber. Size 7.5- and 8.0-mm ETTs that are currently included in the Critical Care Air Transport Team allowance standard were used for the evaluation. Three automatic cuff pressure controllers-Intellicuff, Hamilton Medical Pyton, ARM Medical Cuff Sentry, Outcome Solutions--were used to manage cuff pressures. The fourth group had cuff pressure set at sea level without further adjustment. Each ETT was inserted into a tracheal model and taken to 8,000 feet and then to 16,000 feet at 2,500 ftmin. Baseline cuff pressure at sea level was approximately 25 cmH2O. Results Mean cuff pressure at both altitudes with both size ETTs was as follows Control arm 141-64 cmH2O Pyton 25 - 0.8 cmH2O Cuff Sentry 22- 0.3 cmH2O Intellicuff 29 - 6.6 cmH2O. The mean time that cuff pressure was 30 cmH2O using Intellicuff at both altitudes was 2.8 - 0.8 minutes. Pressure differences from baseline in the control arm and with Intellicuff were statistically significant. Cuff pressure with the Cuff Sentry tended to be lower than indicated on the device. Mean cuff pressures were within the recommended range with all three devices. Intellicuff had difficulty regulating the cuff pressure initially with increases in altitude but was able to reduce the pressure to a safe level during the stabilization period at each altitude. The Pyton and Cuff Sentry allowed the least variation in pressure throughout the evaluation, although the Cuff Sentry set pressure was less than actual pressure.