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The cuff -leak test has been proposed as a clinical method for predicting stridor or respiratory distress caused by laryngeal edema following extubation. However, the true incidence of laryngeal edema in postoperative patients is not clear. We assessed the relationship between upper airway obstruction and the values of cuff -leak pressure in postoperative patients.
One hundred and fifty-eight postoperative patients (123 elective, 35 emergency) were included. After ventilator weaning was accomplished, we measured the airway pressure at which a sound of cuff leakage was audible by a cuff pressure monitor. In 28 cases, the cuff leak pressure was measured during both awake and sedated states.
The cuff leak pressure value was 12.8 ± 10.1 (median 10) mmHg for elective cases and 12.6 ± 10.0 (median 10) for emergency cases (NS). Six patients (3.8%) were not extubated because of high leak pressure and the value was 40.5 ± 16.0 (24 to 60) mmHg. One hundred and forty-three patients were extubated and nine of those (6.3%) were diagnosed as laryngeal edema by laryngoscopy. Seven of those (5.0%) needed reintubation, one was for the reason of massive sputa, three were for granuloma formation, and three (2.1%) were diagnosed as severe laryngeal edema. Patients who developed severe laryngeal edema had a higher leak pressure (27.2 ± 22.7 mmHg) than those who did not, and all of such patients had pressure above 20 mmHg. The sensitivity and the specificity of the test using a threshold value of 20 mmHg for severe laryngeal edema were 97.2% and 40.0%, respectively. The occurrence of severe laryngeal edema was not associated with age, gender, perioperative weight gain, duration of translaryngeal intubation, inner diameter of the endotracheal tube, or serum albumin concentration. However, the cuff leak pressure value >20 mmHg was associated with gender (female, P = 0.02) and inner diameter of the endotracheal tube (P = 0.0017) by multivariate regression. In 28 patients, the cuff leak pressure was 17.8 ± 10.6 during the awake state and 9.9 ± 4.6mmHg under sedative. Because tonus of larynx is considered to be related to cuff leak pressure, it is useful to measure the cuff leak pressure in a sedated state if the patient had a high value in the awake state.
Cuff leak pressure values <20 mmHg at any time are useful to rule out severe laryngeal edema. It may be useful to measure the pressure in a sedated state if the value in the awake state is high.