Factors Affecting the Intracuff Pressure of an Endotracheal Tube during General Anesthesia Using Nitrous Oxide

Baik, Hee Jung; Kim, Jong Hak; Lee, Choon Hi

Abstract

BACKGROUND: It is recommended not to exceed an intracuff pressure of 22 mmHg. We evaluated many factors affecting the intracuff pressure of an endotracheal tube during general anesthesia using nitrous oxide.
METHODS
Eighty adult patients undergoing surgery under general anesthesia using inhalation of nitrous oxide via a large-volume low-pressure cuffed standard tube (Vygon(R)) were enrolled. They were randomly divided into 4 groups according to sex and tube size; group M-1 (n = 20): male, 7.0 mm internal diameter (ID); group M-2 (n = 21): male, 7.5 mm; group F-1 (n = 21): female, 6.5 mm; group F-2 (n = 18): female, 7.0 mm. Specific cuff compliance of the tubes were 8.7 - 9.0nl/torr/ml and residual volumes of tubes of ID 6.5, 7.0 and 7.5 mm were 7.7 +/- 0.4, 11.1 +/- 0.5 and 10.9 +/- 0.5 ml, respectively. Sealing volume (SV), sealing pressure (SP), peak inspiratory pressure (PIP) and tracheal transverse diameter (TD) were measured. When the intracuff pressure reached 22 mmHg cuff volume (DV1) was deflated to SP and the elapsed time to the first deflation point (1-CP22) were recorded. Factors affecting the need for cuff deflation were analyzed.
RESULTS
There were no correlations between SP or SV and TD. The incidence of need for cuff deflation was 30% and 38.1% in group M-1 and M-2, and 52.4% and 27.8% in group F-1 and F-2, respectively. The need for cuff deflation was significantly correlated with SP and duration of anesthesia in males and with SP in females (P < 0.05).
CONCLUSIONS
Factors affecting the need for cuff deflation to maintain intracuff pressure below 22 mmHg were SP and duration of anesthesia in males, and SP in females and not SV/RV, TD or the size of the tube.