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


METHODS
Nonrandomized, repeated, bracketed measures.


METHODS
University research laboratory.


METHODS
Seven neonatal sheep (5.6 +/- 0.6 kg), less than 10 days of age.


METHODS
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).


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 less than .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 less than .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 less than .05) and cardiac output (0.94 +/- 0.11 vs. 1.18 +/- 0.16 L/min, p less than .05) and mean arterial pressure (91 +/- 7 vs. 96 +/- 6 mm Hg, p less than .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.
Martin
L D
LD
Department of Anesthesiology/Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
Wetzel
R C
RC
Bilenki
A L
AL
D000818:Animals; D000831:Animals, Newborn; D001784:Blood Gas Analysis; D006439:Hemodynamics; D055370:Lung Injury; D008954:Models, Biological; D019301:Oleic Acid; D009829:Oleic Acids / Q000506:poisoning; D011175:Positive-Pressure Respiration; D011659:Pulmonary Gas Exchange; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods*; D012756:Sheep
D009829:Oleic Acids; D019301:Oleic Acid