Proportional assist ventilation in low birth weight infants with acute respiratory disease: A comparison to assist/control and conventional mechanical ventilation

Objectives: To compare the physiologic efficacy and safety aspects of propo rtional assist (PA), assist/control (A/C), and intermittent mandatory venti lation (IMV) in very low birth weight infants with acute respiratory illnes s and to test the hypothesis that ventilatory pressure requirements are low er and arterial oxygenation is improved during PA when compared with IMV or A/C at an equivalent inspired oxygen fraction. Study design: Randomized, 3-period, crossover design. Methods: Thirty-six infants were stratified by birth weight (600 to 750, 75 1 to 900, and 901 to 1200 g) and exposed to consecutive 45-minute epochs of the 3 modalities in a sequence chosen at random. Tidal volumes of 4 to 6 m L/kg were targeted during A/C and IMV. The IMV rate was matched to the rate during an A/C test period. PA was adjusted to unload the resistance of the endotracheal tube and the disease-related increase in lung elastic recoil. Results: Compared with A/C and IMV, PA maintained similar arterial oxygenat ion with lower airway and transpulmonary pressures (15% to 44% reduction de pending on the index variable). The oxygenation index decreased by 28% duri ng PA. No adverse events were observed. The number and severity of apneic e pisodes and periods of arterial oxygen desaturations were similar with the 3 modes. Similar results were obtained within each birth weight subgroup. Conclusions: PA safely maintains gas exchange with smaller transpulmonary p ressure changes compared with A/C and IMV. It may therefore offer a way of reducing the incidence of chronic lung disease In low birth weight infants.