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A935
October 16, 2006
9:00 AM - 11:00 AM
Room Hall E, Area F
The Use of Estimation Techniques of Cuff Pressure for Endotracheal Tube Cuff Inflation – Is It Safe?
Henry R. Kroll, M.D., Stanford S. Sankey, Ph.D., Julie A. Fitzgerald, M.D.
Department of Anesthesiology, Henry Ford Hospital, Detroit, Michigan
INTRODUCTION: Tracheal mucosal ischemia occurs when endotracheal tube (ETT) cuff pressure exceeds 40 cm H2O. An under-inflated cuff, pressure less than 24 cm H2O, increases the risk of aspiration of gastric contents, inadequate ventilation, and leakage of anesthetic gases into the operating theater1. Several estimation techniques of cuff inflation have been described as a means to provide the necessary cuff volume and appropriate cuff pressure (CP). These include the pilot baloon palpation, minimum leak, and the minimal occlusive pressure methods2,3. This prospective study was undertaken to determine the CP attained using these estimation techniques for ETT cuff inflation.

METHODS: Following IRB approval and informed consent, 100 patients (48 men and 52 women) undergoing elective procedures with general anesthesia utilizing a cuffed ETT were enrolled. No nitrous oxide was used. Anesthesia providers were blinded to the nature of the study. After intravenous induction and muscle paralysis, an Intermediate Hi-Lo Tracheal Tube (Mallinckrodt, Inc.) was placed and the cuff was inflated with air by the practioners using their standard estimation method for cuff adequacy. The research anesthesiologist then measured CP using a hand-held Cuff Pressure Gauge (King Systems Co.) which was recorded. A CP above 40 cm H2O or below 24 cm H2O was considered unsafe. Data was analyzed between groups using Student's t-tests for continuous variables.

RESULTS: An 8.0 I.D. ETT was used in 98% of the men and a 7.0 I.D. ETT was used in all of the women. Significantly more air (7.3 ml vs. 6.1ml) was used to inflate the cuff in the men compared to the women (p= .01). Using the estimation methods as indicators of appropriate cuff inflation, only 21% of the CPs were in the safe range. 66% of the patients had a CP greater than 40 cm H2O and 13% had a CP less than 24 cm H2O. CP was not significantly different between the ETT tube sizes (p= .42). There was a significant difference (p<.001) between the mean volume of air used in the high CP group, 7.35 ml, compared to the group with a safe CP, 5.36 ml. Similarly, the unsafe CP group had a mean volume of 7.04 ml compared to the safe CP group of 5.36 ml (p<.01). These results did not change qualitatively when stratified for tube size (7.0 vs. 8.0). However, regardless of tube size, there was no statistically significant difference between the volume of air in the low CP group, 5.50 ml, compared to the volume in the safe CP group, 5.36 ml (p=.82).

REFERENCES:

1. Anesthesia and Perioperative Complications, 2nd Edition, Benumof J.L.

2. Hess D.R., Resp. Journal: 44(7); 759-771

3. Fernandez R, Crit Care Med: 18(12); 1423-1426.[table1]

Anesthesiology 2006; 105: A935
COMPARISON OF ENDOTRACHEAL TUBE CUFF INFLATION VOLUMES IN THE DIFFERENT CUFF PRESSURE GROUPS
GROUPCUFF PRESSURENMEAN VOLUME OF AIR mlSTD DEVP-VALUE
1006.692.31----
SAFE

vs
24 - 40cm H2O215.361.720.82
LOW< 24cm H2O135.501.76
SAFE

vs
24 - 40cm H2O215.361.72< 0.001∗
HIGH> 40cm H2O667.352.31
SAFE

vs
24 - 40cm H2O215.361.72< 0.01∗
UNSAFE< 24 or > 40 cm H2O797.042.32
Statistical significance based on Student's t-test