Adaptive support ventilation with protocolized de-escalation and escalation does not accelerate tracheal extubation of patients after nonfast-track cardiothoracic surgery.

BACKGROUND: It is uncertain whether adaptive support ventilation (ASV) accelerates weaning of nonfast-track cardiothoracic surgery patients. A lower operator set %-minute ventilation with ASV may allow for an earlier definite switch from controlled to assisted ventilation, potentially hastening tracheal extubation. We hypothesized that ASV using protocolized de-escalation and escalation of operator set %-minute ventilation (ASV-DE) reduces time until tracheal extubation compared with ASV using a fixed operator set %-minute ventilation (standard ASV) in uncomplicated patients after nonfast-track coronary artery bypass graft. METHODS: We performed a randomized controlled trial comparing ASV-DE with standard ASV. With ASV-DE, as soon as body temperature was >35.0°C with pH >7.25, operator set %-minute ventilation was decreased stepwise to a minimum of 70%. RESULTS: Sixty-three patients were randomized to ASV-DE, and 63 patients to standard ASV. The duration of mechanical ventilation was not different between groups (10.8 [6.5-16.1] vs 10.7 [6.6-13.9] hours, ASV-DE versus standard ASV; P = 0.32). Time until the first assisted breathing period was shorter (3.1 [2.0-6.7] vs 3.9 [2.1-7.5] hours) and the number of assisted ventilation episodes was higher (78 [34-176] vs 57 [32-116] episodes), but differences did not reach statistical significance. The duration of assisted ventilation episodes that ended with tracheal extubation was different between groups (2.5 [0.9-4.6] vs 1.4 [0.3-3.5] hours, ASV-DE versus standard ASV; P < 0.05). CONCLUSION: Compared with standard ASV, weaning of patients after nonfast-track coronary artery bypass graft using ASV with protocolized de-escalation and escalation does not shorten time to tracheal extubation.

Weaning automation with adaptive support ventilation: a randomized controlled trial in cardiothoracic surgery patients.

BACKGROUND: Adaptive support ventilation (ASV) is a microprocessor-controlled mode of mechanical ventilation that switches automatically from controlled ventilation to assisted ventilation and selects ventilatory settings according to measured lung mechanics. METHODS: In a randomized controlled trial, non-fast-track coronary artery bypass grafting patients' lungs were ventilated with ASV or pressure-controlled/pressure-support ventilation (control) to compare time until tracheal extubation, duration of controlled ventilation versus assisted ventilation, and ventilation characteristics. RESULTS: One hundred twenty-eight consecutive patients were randomized. ASV patients had their tracheas extubated after median 16.4 and interquartile range 12.5-20.8 hr, and control patients after 16.3 (13.7-19.3) hr, respectively (P = 0.97). The percentage of time patients were on assisted ventilation (expressed as the median percentage of total duration of ventilation) was 43% (28%-67%) in the ASV group and 52% (33%-75%) in the control group (P < 0.05). However, the number of switches from controlled to assisted ventilation was higher in the ASV group (43.0 [14.0-74.0]) than in the control group (4.0 [2.0-9.0]) (P < 0.001). In ASV patients, mean tidal volumes were significantly larger during controlled ventilation than in control patients (8.6 +/- 0.8 mL/kg predicted body weight vs 7.1 +/- 1.4 mL/kg predicted body weight; P = 0.05), and no differences in tidal volumes were found during assisted ventilation. CONCLUSION: Weaning automation with ASV is feasible and safe in non-fast-track coronary artery bypass grafting patients. Time until tracheal extubation with ASV equals time until tracheal extubation with standard weaning and allows for frequent (automatic) switches between controlled and assisted ventilation.