Changes in energy expenditures while reducing pressure support as a predictor of successful spontaneous breathing trial

The objective: to assess changes in energy expenditures (EE) when reducing pressure support (PS) as a predictor of the patient’s readiness for transfer to spontaneous breathing. Subjects and methods. The study included 33 patients who had been on mechanical ventilation for at least 7 days. PS reduced from 20 to 4 cmH2O at the interval of 4 cmH2O. At each level, the patient's EE were measured with indirect calorimetry. At the end of the study, spontaneous breathing trial (SBT) was performed. Results. In 22 (67%) patients, at least one episode of a statistically significant increase in EE was observed upon transition to a lower level of PS (Group 1). In remaining 11 (33%) patients, with decreased level of PS, EE decreased or did not significantly change (Group 2). SBT was successful in 14 out of 22 patients from Group 1 and all 11 patients from Group 2. The absence of episodes of increased EE during decreased PS was a predictor of successful SBT (sensitivity – 44%, specificity – 100%). Conclusion. The absence of episodes of a statistically significant increase in EE during the transition to a lower level of PS is a highly specific predictor of successful SBT.