Recommended pressure of the tracheal tube cuff is not obtained by inflation with fixed volume of air: A bench test using a pig trachea

Abstract

Objective: To investigate tracheal cuff pressures by inflation of fixed volume of air in an experimental condition using a pig trachea.

Methods: A fresh pig trachea was intubated with a tracheal tube of 7, 7.5, or 8mm inner diameter (ID). Then the cuff of the tube was inflated with fixed volume of air (5mL or 10mL) and cuff pressure was measured using a manometer. In addition, pressure-volume curve of the cuff was obtained by inflation of increasing volume of air.

Results: Cuff pressure (cmH2O) is shown by mean (95% confidence interval). Adult male-sized trachea (17mm ID) inflated with 5mL air: tracheal tube ID 7mm; 11.5 (11-12), ID 7.5mm; 9.4 (8.6-10.3), ID 8mm; 10.8 (10.1-11.5). Adult male-sized trachea inflated with 10mL of air: ID 7mm; 53.8 (51.5-56.1), ID 7.5mm; 59.3 (56.9-61.7), ID 8mm; 60.5 (57.1-63.9). Adult female-sized trachea (ID 14mm) inflated with 5mL of air: ID 7mm; 39.1 (36.4-41.8), ID 7.5mm; 32.9 (31.3-34.5), ID 8mm; 40.2 (37.4-43.1). In adult female-sized trachea inflated with 10mL of air, all measurements showed pressure exceeding the upper limit of the manometer (i.e., 120 cmH₂O). Pressure-volume curve revealed that the range of air volume required to inflate the cuff within recommended range of pressure was only about 1mL.

Conclusions: It is difficult to obtain the recommended range of cuff pressure by inflating any fixed volume of air. Protocols in prehospital care including this method should be revised. Following emergent tracheal intubation, the cuff pressure should be adjusted as early as possible.