Physiologic Effects of Reconnection to the Ventilator for 1 Hour Following a Successful Spontaneous Breathing Trial

BACKGROUND: Reconnection to the ventilator for 1 h following a successful spontaneous breathing trial (SBT) may reduce reintubation rates compared with direct extubation. However, the physiologic mechanisms leading to this effect are unclear. RESEARCH QUESTION: Does reconnection to the ventilator for 1 h reverse alveolar derecruitment induced by SBT, and is alveolar derecruitment more pronounced with a T -piece than with pressure-support ventilation (PSV)? STUDY DESIGN AND METHODS: This is an ancillary study of a randomized clinical trial comparing SBT performed with a T -piece or with PSV. Alveolar recruitment was assessed by using measurement of end-expiratory lung volume (EELV). RESULTS: Of the 25 patients analyzed following successful SBT, 11 underwent SBT with a T -piece and 14 with PSV. At the end of the SBT, EELV decreased by - 30% (95% CI, - 37 to - 23) compared with baseline prior to the SBT. This reduction was greater with a T -piece than with PSV: - 43% (95% CI, - 51 to - 35) vs - 20% (95% CI, - 26 to - 13); P < .001. Following reconnection to the ventilator for 1 h, EELV accounted for 96% (95% CI, 92 to 101) of baseline EELV and did not signi fi cantly differ from prior to the SBT ( P = .104). Following 10 min of reconnection to the ventilator, EELV wasted at the end of the SBT was completely recovered using PSV ( P = .574), whereas it remained lower than prior to the SBT using a T -piece ( P = .010). INTERPRETATION: Significant alveolar derecruitment was observed at the end of an SBT and was markedly more pronounced with a T -piece than with PSV. Reconnection to the ventilator for 1 h allowed complete recovery of alveolar derecruitment.