Automatic tube compensation as an adjunct for weaning in patients with severe neuroparalytic snake envenomation requiring mechanical ventilation: a pilot randomized study

Abstract

Objective: This study aimed to evaluate if the combination of pressure-support ventilation (PSV) and automatic tube compensation (ATC) is superior to PSV alone in weaning patients with severe neurotoxic snake envenoming receiving mechanical ventilation.

Methods: Forty-one patients on volume controlled continuous mandatory ventilation were randomized to weaning with PSV alone (PSV group, 18 patients) or PSV plus ATC (ATC group, 23 patients). In both groups, PSV was initially set at 15 cm H(2)O, and CPAP at 5 cm H(2)O, with progressive downward titration. The ATC group additionally, received inspiratory ATC at 100% through a ventilator-software-driven algorithm. The primary outcome measure was weaning duration. Secondary outcomes studied included reintubation rate, occurrence of pneumonia, and hospital mortality.

Results: Median time to presentation to hospital after snake bite was 7 hours (interquartile range [IQR] 4-9.5 h). Median duration of weaning was significantly shorter in the ATC group than in the PSV group (8 h, 95% confidence interval 6.6-9.4 h vs 12 h, 95% confidence interval 9.9-14.1 h, P = .03 via log-rank test). Median duration of mechanical ventilation and intensive-care-unit stay were similar between the PSV and the ATC groups (36.5 h, IQR 23.0-52.0 h vs 41.0 h, IQR 25.0-48.0 h, and 3.5 d, IQR 2-4 d vs 3 d, IQR 2-4 d, respectively). Three patients in the PSV group and none in the ATC group developed pneumonia (P = .08). No patient in either group needed reintubation or died in hospital.

Conclusion: The addition of ATC to a standard PSV-based weaning protocol significantly shortened time needed to wean patients with severe neurotoxic snake envenoming, without changing the duration of medical care, morbidity, or mortality.