Pressure in the cuffs of tracheal tubes at altitude.

Pressures in the cuffs of three commonly used tracheal tubes (Portex Profile Softseal, Mallinckrodt Lo-Contour and Mallinckrodt Hi-Contour, size 8.0 mm and 9.0 mm internal diameter), inflated with air, were measured during simulated ascents in an altitude chamber to 10 000 ft. There was no detectable difference in performance between sizes for each type of tracheal tube. When averaged over the two sizes for each type of tube, cuff pressure reached the critical perfusion pressure 50 cmH2O (37 mmHg) for tracheal mucosa at a higher altitude in the Portex Profile Softseal (2837 ft, 95% CI 2488-3186 ft) than in the Mallinckrodt Lo-Contour (2128 ft, 95% CI 1779-2476 ft; p = 0.02) and Mallinckrodt Hi-Contour (1820 ft; 95% CI 1471-2168 ft; p = 0.002) tracheal tubes. When the cuffs of the 9.0-mm tracheal tubes were inflated with saline, much smaller increases in pressure were measured with increasing altitude, although inflation of the cuffs with saline was technically difficult. Commonly used tracheal tubes with air-inflated cuffs can be used for aeromedical retrieval, but air should be evacuated from the cuffs after increases in altitude of as little as 2000-3000 ft.