Evaluation of a New Method for Measurement of Minute Ventilation Recovery Time

PURPOSE: To determine if the measurement of minute ventilation recovery time (V˙_ERT), a recently proposed predictor of extubation outcome, can be reproduced using a more practical, simpler method.

METHODS: A case series with convenience sampling was performed in the surgical intensive care unit of a tertiary-care hospital. Nineteen patients were enrolled during weaning from mechanical ventilation, prior to the initial extubation attempt. Within-subject comparisons of V˙_ERT were performed, using 2 alternative methods for measuring baseline V˙_E and one alternative method for determining the threshold for recovery of V˙_E during the final spontaneous breathing trial prior to extubation. Comparison methods for baseline V˙_E included an 8-hour average and the last V˙_E measurement prior to the spontaneous breathing trial. The alternative threshold for defining recovery of V˙_E was 100% of the baseline value (vs 110% in the original method).

RESULTS: The study subjects were primarily cardiac surgery patients (63%) and were ventilated for a median of 5 days prior to extubation. V˙_ERT calculated using the 8-hour average or the last V˙_E measurement prior to the spontaneous breathing trial as baseline, and a threshold of 100% of baseline V˙_E to define recovery most closely approximated V˙_ERT obtained by the original method and similarly classified patients at high risk for reintubation (kappa statistic = 0.78 ± 0.2).

CONCLUSIONS: V˙_ERT can be determined using a simpler method for measuring both baseline V˙_E and the recovery threshold. These methodological modifications may increase the feasibility of measuring V˙_ERT, while reproducing the results obtained by the original method.