Physiologic Effects of 3 Different Neonatal Volume-Targeted Ventilation Modes in Surfactant-Deficient Juvenile Rabbits

BACKGROUND: Different brands of volume-targeted modes may vary the location of tidal volume (V T ) monitoring and whether peak inspiratory pressure is adjusted based on inspiratory, expiratory , or leak-compensated V T . These variables may result in different levels of support provided to patients, especially when an endotracheal tube (ETT) leak is present. We hypothesized that there would be no differences in gas exchange, triggering, or work of breathing between volume-targeted modes of 3 different brands of equipment in a surfactant-deficient, spontaneously breathing animal model with and without an ETT leak. METHODS: Twelve rabbits (mean ± SD 1.61 ± 0.20 kg) were sedated, anesthetized, intubated, lavaged with 0.9% saline solution, and randomized in a crossover design so that each animal was supported by 3 different volume-targeted modes at identical settings with and without an ETT leak. After 30 min, arterial blood gas, V T , and esophageal and airway pressure were recorded for each condition, and pressure-rate product and percentage of successfully triggered breaths were calculated. RESULTS: Gas exchange and the pressure-rate product were not different between the ventilators in the absence of an ETT leak. When an ETT leak was introduced, volume-guarantee modes allowed a higher percentage of triggered breaths and peak inspiratory pressure, which resulted in higher minute ventilation, pH, and lower P aCO 2 than the pressure-regulated volume control mode ( P < .05). CONCLUSIONS: When a moderate ETT leak was present, volume-targeted modes that used proximal V T monitoring and triggering with adaptive leak compensation capabilities appeared more effective in providing ventilation support than did a ventilator that used measurements obtained from the back at the ventilator and does not have leak compensation.