Airway pressure release ventilation in a neonatal lamb model of acute lung injury

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Abstract

Objective.

To determine if airway pressure release ventilation (APRV) is feasible in a neonatal animal model with acute lung injury.

Design.

Nonrandomized, repeated, bracketed measures.

Setting.

University research laboratory.

Subjects.

Seven neonatal sheep (5.6 ± 0.6 kg), <10 days of age.

Interventions.

Acute lung injury was induced by oleic acid infusion and cardiorespiratory profiles were compared during spontaneous ventilation at ambient airway pressure, continuous positive airway pressure (CPAP), APRV, and conventional positive-pressure ventilation (PPV).

Measurements and Results.

Oleic acid resulted in acute lung injury with stable cardiorespiratory status during the 3-hr study period. Mean airway pressure (Paw) was comparable for all three positive-pressure modes (CPAP 13.4 ± 1.5, APRV 13.5 ± 1.4, PPV 13.9 ± 1.4 cm H2O, NS). After acute lung injury, CPAP increased arterial oxygenation compared with spontaneous ventilation (77.3 ± 6.9 vs. 57.7 ± 4.2 torr [10.3 ± 0.9 vs. 7.7 ± 0.6 kPa], p < .05), and this increase was maintained during APRV (73.3 ± 5.6 vs. 77.3 ± 6.9 torr [9.8 ± 0.7 vs. 10.3 ± 0.9 kPa], NS). Alveolar ventilation was increased by APRV compared with CPAP (Paco2 29 ± 1 vs. 41 ± 2 torr [3.9 ± 0.1 vs. 5.4 ± 0.3 kPa], p < .05) without impairment of cardiovascular performance (cardiac output 1.18 ± 0.16 vs. 1.20 ± 0.17 L/min, NS). To achieve ventilation equivalent to APRV during PPV, peak Paw was greater (36.4 ± 3.2 vs. 19.7 ± 1.7 cm H2O, p < .05) and cardiac output (0.94 ± 0.11 vs. 1.18 ± 0.16 L/min, p < .05) and mean arterial pressure (91 ± 7 vs. 96 ± 6 mm Hg, p < .05) were decreased during PPV compared with APRV.

Conclusions.

In this neonatal laboratory model of acute lung injury, APRV maintained oxygenation and augmented alveolar ventilation compared with CPAP. Compared with PPV, APRV provided similar ventilation and oxygenation, but at lower peak Paw than PPV, without compromising cardiovascular performance. (Crit Care Med 1991: 19:373)

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