Interest of an objective evaluation of cough during weaning from mechanical ventilation

This study aimed to evaluate an objective measure of cough strength, the peak cough expiratory flow (PCEF), as a predictive criterion of success or failure of extubation.

Patients under mechanical ventilation for more than 24 h who successfully passed the spontaneous breathing trial were included in the study. Just before extubation, PCEF was measured with an electronic flowmeter.

A total of 130 patients were included. The median duration of mechanical ventilation before extubation was 8 days (4-17). Fourteen patients (10.8%) failed extubation. The sole factor significantly associated with extubation failure was the measure of PCEF. The patients who did not cough at order had a higher rate of extubation failure than those who did (P = 0.03). The mean PCEF of patients who failed extubation (36.3 +/- 15 l/min) was significantly lower than the one of patients who succeeded (63.6 +/- 32 l/min) (P < 0.001). The optimal cut-off value of PCEF was 35 l/min. Overall, an inability to cough at order or a PCEF < or =35 l/min predicted extubation failure with a sensitivity of 79% and a specificity of 71%. The risk of extubation failure was 24% for the patients who did not cough at order or with a PCEF < or =35 l/min and 3.5% for those with a PCEF >35 l/min [RR = 6.9 (95% CI, 2-24); P = 0.002].

This study confirmed the interest of measuring the PCEF to predict extubation outcome in patients having successfully passed the spontaneous breathing trial.