Work of breathing as a weaning parameter in mechanically ventilated patients.

STUDY OBJECTIVE

Predicting patient responses to changes in ventilatory support or weaning is primarily based on bedside measure of respiratory mechanics and clinical judgement. Work of breathing (WOB) has been considered to be the best predictive factor in weaning. This study evaluated patient WOB as a predictive measure of weaning and extubation.

DESIGN

Blinded, descriptive evaluation of the accuracy of preextubation values of patient WOB in predicting successful extubation.

SETTING

Critical care units of 500-bed major teaching hospital of the University of Hawaii.

PATIENTS

Twenty-four patients from the medical and surgical ICU were enrolled in the study. Patient diagnoses included COPD, ARDS, pneumonia, and renal failure.

MEASUREMENTS AND MAIN RESULTS

In all patients, weaning from mechanical ventilation was accomplished by the clinical ICU teams who were blinded to the patient WOB. After extubation, patient WOB was compared with extubation attempts. In 14 patients, WOB was elevated above normal levels prior to successful extubation, while only 1 patient whose WOB was abnormal prior to extubation required reintubation within 24 h. WOB and clinical parameters were normal in 10 successfully extubated patients.

CONCLUSIONS

In this group of mechanically ventilated patients, measurement of patient WOB was less accurate than conventional weaning parameters and clinical judgement for predicting successful extubation. This clinical evaluation study suggests that WOB alone is inadequate as a weaning parameter.