Predicting Extubation Outcome by Cough Peak Flow Measured Using a Built-in Ventilator Flow Meter

Successful weaning from mechanical ventilation depends on the patient's ability to cough efficiently. Cough peak flow (CPF) could predict extubation success using a dedicated flow meter but required patient disconnection. We aimed to predict extubation outcome using an overall model, including cough performance assessed by a ventilator flow meter.

This was a prospective observational study conducted from November 2014 to October 2015. Before and after a spontaneous breathing trial, subjects were encouraged to cough as strongly as possible before freezing the ventilator screen to assess CPF and tidal volume (V_T) in the preceding inspiration. Early extubation success rate was defined as the proportion of subjects not re-intubated 48 h after extubation. Diagnostic performance of CPF and V_T was assessed by using the area under the curve of the receiver operating characteristic curve. Cut-off values for CPF and V_T were defined according to median values and used to describe the performance of a predictive test combining them with risk factors of early extubation failure.

Among 673 subjects admitted, 92 had a cough assessment before extubation. For the 81 subjects with early extubation success, the median CPF was -67.7 L/min, and median V_T was 0.646 L. For the 11 subjects with early extubation failure, the median CPF was -57.3 L/min, and median V_T was 0.448 L. Area under the curve was 0.61 (95% CI 0.37-0.83) for CPF and 0.64 (95% CI 0.42-0.84) for CPF/V_T combined. After dichotomization (CPF < -60 L/min or V_T > 0.55 L), there was a synergistic effect to predict early extubation success (P < .001). The predictive value of success reached 94.2% for CPF/V_T combined. The overall model including pH before extubation < 7.45 reached a 66.7% predictive value of failure.

CPF measured using the flow meter of an ICU ventilator was able to predict extubation success and to build a composite score to predict extubation failure. The results were close to that found in previous studies that used a dedicated flow meter. This could help to identify high-risk subjects to prevent extubation failure. (ClinicalTrials.gov registration NCT02847221.).