A study of intracuff pressure measurements, trends and behaviour in patients during prolonged periods of tracheal intubation.

Intracuff pressure (c.p.) was measured continuously in 12 patients during prolonged periods of tracheal intubation. High residual volume--low pressure (floppy) and low residual volume--high pressure (conventional) cuffs were studied. The mean baseline c.p. at minimal occluding pressure was significantly smaller in floppy cuffs than in conventional cuffs. With coughing, the peak pressures in both cuff types were much greater than the baseline pressures but did not differ significantly from each other. On the basis of our observations, we recommend a simplification of the test methods for cuffs and tube collapse. We believe universal testing to 300 mm Hg (40 kPa) to be reasonable and to incorporate a realistic safety factor. Intracuff pressure tends to diminish with time, but there is a poor correlation between the rate of pressure decrease and elapsed time. As this decrease is not accurately predictable, gas should be added to the cuff as required, rather than at intervals. Other features of cuff behaviour are discussed and suggestions made to explain some anomalies occasionally observed in the cuff pressure behaviour pattern.