Background: Adaptive-support ventilation (ASV) is a minute ventilation-controlled mode governed by a closed-loop algorithm. With ASV, tidal volume and respiratory rate are automatically adjusted to minimize work of breathing. Studies indicate that ventilation in ASV enables more rapid weaning. The authors conducted a randomized controlled trial to determine whether ventilation in ASV results in a shorter time to extubation than pressure-regulated volume-controlled ventilation with automode (PRVCa) after cardiac surgery.
Methods: Fifty patients were randomly assigned to ASV or PRVCa after elective coronary artery bypass grafting. Respiratory weaning progressed through three phases: phase 1 (controlled ventilation), phase 2 (assisted ventilation), and phase 3 (T-piece trial), followed by extubation. The primary outcome was duration of intubation (sum of phases 1-3). Secondary outcomes were duration of mechanical ventilation (sum of phases 1 and 2), number of arterial blood gas samples, and manual ventilator setting changes made before extubation.
Results: Forty-eight patients completed the study. The median duration of intubation was significantly shorter in the ASV group than in the PRVCa group (300 [205-365] vs. 540 [462-580] min; P < 0.05). This difference was due to a reduction in the duration of mechanical ventilation (165 [120-195] vs. 480 [360-510] min; P < 0.05). There were no significant differences between the ASV and PRVCa groups in the number of arterial blood gas samples taken or manual ventilator setting changes made.
Conclusions: ASV is associated with earlier extubation, without an increase in clinician intervention, when compared with PRVCa in patients undergoing uncomplicated cardiac surgery.