Use of Cough Peak Flow Measured by a Ventilator to Predict Re-Intubation When a Spirometer Is Unavailable

BACKGROUND: A ventilator includes the function to measure flow velocity. We aimed to compare the predictive accuracy for re-intubation diagnosed by cough peak flow (CPF) measured by a spirometer and a ventilator. METHODS: Endotracheally intubated subjects who passed a spontaneous breathing trial were enrolled. Before extubation, CPF was measured by a spirometer and a ventilator, respectively. Re-intubation was recorded at 72 h after extubation. RESULTS: A total of 126 subjects were enrolled. Among them, 15 subjects (12%) experienced re-intubation. CPF was lower in re-intubated subjects than those without re-intubation (measured by a spirometer: 54 +/- 30 L/min vs 86 +/- 37 L/min, P < .001; and measured by a ventilator: 50 +/- 22 L/min vs 80 +/- 26 L/min, P < .001). CPF measured by a spirometer and a ventilator had similar area under the curve of receiver operating characteristic (0.79 vs 0.83, P = .26). When a CPF of 56.4 L/min was measured by a spirometer as cutoff value, the sensitivity and specificity to distinguish re-intubation was 73 and 87%, respectively. When it was measured by a ventilator, the cutoff value, sensitivity, and specificity were 56 L/min, 73%, and 85%, respectively. CONCLUSIONS: CPF measurement by a ventilator was convenient, affordable, and safe. It had a predictive accuracy for re-intubation similar to that of a spirometer.