Physiological effects of reconnection to the ventilator for 1 hour after successful spontaneous breathing trial

Abstract:

Background

Reconnection to the ventilator for 1 hour after a successful spontaneous breathing trial (SBT) may reduce reintubation rate as compared to direct extubation. However, the physiological mechanisms leading to this effect are unclear.

Research question

Does reconnection to the ventilator for 1 hour 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

Ancillary study of a randomized clinical trial comparing SBT performed with a T-piece or with PSV. Alveolar recruitment was assessed using measurement of end-expiratory lung volume (EELV).

Results

Out of 25 patients analyzed after successful SBT, 11 underwent SBT with a T-piece and 14 with PSV. At the end of the SBT, EELV decreased by -30% (95% confidence interval, -37% to -23%) compared with baseline before 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<0.001. After reconnection to the ventilator for 1 hour, EELV accounted for 96% (95% CI, 92% to 101%) of baseline EELV and did not significantly differ from before the SBT (p=0.104). After 10 minutes of reconnection to the ventilator, EELV wasted at the end of the SBT was completely recovered using PSV (p=0.574) whereas it remained lower than before the SBT using T-piece (p=0.010).

Interpretation

Significant alveolar derecruitment was observed at the end of a SBT, and was markedly more pronounced with a T-piece than with PSV. Reconnection to the ventilator for 1 hour allowed complete recovery of alveolar derecruitment.

Clinical trial registration

NCT04227639