Thenar oxygen saturation (StO_2) alterations during a spontaneous breathing trial predict extubation failure

Background

Weaning from mechanical ventilation (MV) is a cardiovascular stress test. Monitoring the regional oxygenation status has shown promising results in predicting the tolerance to spontaneously breathe in the process of weaning from MV. Our aim was to determine whether changes in skeletal muscle oxygen saturation (StO_2) measured by near-infrared spectroscopy (NIRS) on the thenar eminence during a vascular occlusion test (VOT) can be used to predict extubation failure from mechanical ventilation

Methods

We prospectively studied 206 adult patients with acute respiratory failure receiving MV for at least 48 h from a 30-bed mixed ICU, who were deemed ready to wean by their physicians. Patients underwent a 30-min spontaneous breathing trial (SBT), and were extubated according to the local protocol. Continuous StO_2 was measured non-invasively on the thenar eminence. A VOT was performed prior to and at 30 min of the SBT (SBT_30). The rate of StO_2 deoxygenation (DeO_2), StO_2 reoxygenation (ReO_2) rate and StO_2 hyperemic response to ischemia ( H _AUC) were calculated

Results

Thirty-six of the 206 patients (17%) failed their SBT. The remainder 170 patients (83%) were extubated. Twenty-three of these patients (13.5%) needed reinstitution of MV within 24 h. Reintubated patients displayed a lower H _AUC at baseline, and higher relative changes in their StO_2 deoxygenation rate between baseline and SBT_30 (DeO_2 Ratio). A logistic regression-derived StO_2 score, combining baseline StO_2, H _AUC and DeO_2 ratio, showed an AUC of 0.84 (95% CI 0.74–0.91) for prediction of extubation failure

Conclusions

Extubation failure was associated to baseline and dynamic StO_2 alterations during the SBT. Monitoring StO_2-derived parameters might be useful in predicting extubation outcome.