Evaluation of a new method for measurement of minute ventilation recovery time.

PURPOSE

To determine if the measurement of minute ventilation recovery time (V (E)RT), 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 (E)RT 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 (E)RT 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 (E)RT obtained by the original method and similarly classified patients at high risk for reintubation (kappa statistic = 0.78 +/- 0.2).

CONCLUSIONS

V (E)RT 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 (E)RT, while reproducing the results obtained by the original method.