Effect of tracheal gas insufflation during weaning from prolonged mechanical ventilation: a preliminary study.

BACKGROUND Tracheal gas insufflation reduces inspired tidal volume and minute ventilation in spontaneously breathing patients and may facilitate weaning from mechanical ventilation. OBJECTIVE To determine if tracheal gas insufflation can reduce ventilatory demand during weaning trials in patients who require prolonged mechanical ventilation. METHODS A reduction in ventilatory demand was defined as a relative decrease in tidal volume, minute ventilation, and mean inspiratory flow during trials with tracheal gas insufflation compared with the values during trials without this therapy. A total of 14 subjects underwent T-piece trials with and without insufflation (flow rate 6 L/min) on 2 consecutive days; the order of insufflation was randomized. Tidal volume, minute ventilation, and mean inspiratory flow were measured at baseline (without insufflation) and 2 hours later. RESULTS Differences in ventilatory demand were not significant when comparisons were made for condition (tracheal gas insufflation vs no flow) or time (baseline vs 2 hours) for the total group (P = .48). Subjects were classified post hoc as responders (n = 9) or nonresponders (n = 5). Comparisons between responders and nonresponders indicated a significant (P = .02) 3-way multivariate interaction for group (responder vs nonresponder), condition (tracheal gas insufflation vs no flow), and time (baseline vs 2 hours) for ventilatory demand variables. CONCLUSION Tracheal gas insufflation can reduce ventilatory demand during weaning trials in some patients who require mechanical ventilation.