Pressure-rate products and phase angles in children on minimal support ventilation and after extubation.

ABSTRACT

OBJECTIVE: To compare the pressure-rate products and phase angles of children during minimal support ventilation and after extubation. DESIGN AND SETTING: Prospective, randomized single-center trial in a pediatric intensive care unit in a tertiary children's hospital. METHODS: Seventeen endotracheally intubated, mechanically ventilated children were placed on T-piece, T-piece with heliox, continuous positive airway pressure, and pressure support in random order. Esophageal pressure swings, phase angles, respiratory mechanics, and physiological parameters were measured on these modes and after extubation. MEASUREMENTS AND RESULTS: Pressure-rate product postextubation was significantly higher than on support modes. For each mode and after extubation they were pressure support 198+/-31, continuous positive airway pressure 237+/-30, T-piece 323+/-47, T-piece/heliox 308+/-61, and extubation 378+/-43 cmH2O/min. Phase angles were significantly higher during T-piece ventilation than pressure support but not did not differ significantly from postextubation. CONCLUSIONS: Assessment of effort of breathing during even minimal mechanical ventilation may underestimate postextubation effort in children. Postextubation pressure-rate product and hence "effort of breathing" in children is best approximated by T-piece ventilation.