We have previously shown in patients receiving adaptive support ventilation (ASV) that there existed a Transition %MinVol (TMV%) where the patient's work of breathing began to reduce. In this study, we tested the hypothesis that higher TMV% would be associated with poorer outcome in patients with acute respiratory failure.Materials and methods:
In this prospective observational study, we recruited patients with acute respiratory failure on ASV between December 2012 and September 2013 in a mixed ICU. The TMV% was determined by adjusting % MinVol until mandatory respiratory frequency was between 0 and 1 breath/min. TMV% was measured on the first two days of mechanical ventilation.Results:
A total of 337 patients (age: 70 ± 16 years) were recruited. In patients whose TMV% increased between Day 1 and Day 2, aOR for mortality was 7.0 (95%CI = 2.7–18.3, p < 0.001) compared to patients whose TMV% decreased. In patients whose TMV% was unchanged between Day 1 and Day2, aOR for mortality was 3.91 (95%CI = 1.80–8.22, p < 0.01).Conclusions:
An increase, or lack of decrease, of TMV% from Day 1 to Day 2 was associated with higher risk of in-hospital death.