Should natriuretic peptide B-type be used to predict weaning failure in mechanically ventilated patients?

Background

Heart failure and pulmonary edema have been implicated as causes for weaning failure in mechanically ventilated patients; however, the identification of these conditions could be challenging in critically ill patients. The natriuretic peptide B-type (BNP) level has been used to evaluate volemia and cardiac function in patients with heart failure, but no data have been published about the use of BNP to guide weaning in mechanically ventilated patients.

Objective

This study was performed to evaluate whether the BNP level could be useful to predict weaning failure or success in patients mechanically ventilated for more than 48 hours.

Methods

Sixty-three consecutive patients mechanically ventilated for more than 48 hours in a medical/surgical ICU and who were included in our weaning protocol had their BNP level (pg/ml) recorded immediately before a T trial. The decision about extubation or reintubation was made by an attending physician not involved in this study and blinded for the BNP level. Weaning failure was defined by the T-trial intolerance or need for reintubation in the first 48 hours after extubation.

Results

Weaning failure was observed in 16 patients (25%), seven who failed during the T trial and nine who were extubated but needed reintubation within 48 hours. The BNP level was greater in the failure group when compared with the success group (712.6 ± 151.9 vs 295.3 ± 42.4 respectively, P = 0.02). The patients who were reintubated had a BNP level (864 ± 128.8) higher than the success group (P < 0.001) but there were no differences between the reintubation group and T-trial failure (517.8 ± 146).

Conclusion

BNP recorded before a T trial can be helpful to predict weaning outcome in patients mechanically ventilated for more than 48 hours.