Behavior of B-type natriuretic peptide during mechanical ventilation and spontaneous breathing after extubation.

Background. The behavior of B-type natriuretic peptide (BNP) is assessed during mechanical ventilation (MV) and spontaneous breathing after extubation in critical patients. Methods. Thirty patients admitted in the Intensive Care Unit (ICU) were enrolled. BNP, fluid balance (1713), airway pressure (AP) and dobutamine infusion needing (DP) were registered in three stages: TO, admission to ICU; T1, before extubation; T2, 24 h after extubation. Results. Patients with congestive heart failure (CHF) had BNP values higher than other patients. The value of BNP during MV was greater than normal in all patients. The cut-off to discriminate patients with heart failure during MV was 286 pg.mL(-1) (sensitivity: 86%; specificity: 90%). The increase of BNP during MV directly correlated with FB and inversely correlated with A-P and DP. The plasmatic level of BNP remained higher than normal values 24 h after extubation. Conclusion. The underlying disease of all ICU patient seems to play a relevant role for BNP production and is probably linked to different aspects of therapeutic approach required by the patient. Our data suggest a cut-off value of BNP higher than the usual is necessary to discriminate mechanically-ventilated patients without CHF. This study should be repeated with an enlarged population.