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Objective: The pathophysiology of early pulmonary acute respiratory distress syndrome (ARDSp) is different compared to that of extrapulmonary ARDS (ARDSexp). We aimed to compare the hemodynamic and respiratory responses to prone position between ARDSp and ARDS in the present study.
Design: Prospective controlled clinical study.
Setting: General intensive care unit of university hospital.
Methods: Eleven intensive care unit patients with ARDS (6 ARDS , 5 ARDS ) were included in the study. Hemodynamic and respiratory parameters were recorded at supine position (Supine) and also at 50 min (Prone50mjn) and 130 min (Prone130 min) after establishment of prone position.
Interventions: Invasive hemodynamic monitoring via pulmonary and radial artery catheters, and prone positioning.
Measurements and Main Results: In both groups, arterial oxygen partial pressure increased and the alveolar-arterial oxygen tension difference decreased at Prone50min and Prone130 min compared with Supine (p<0.05). Respiratory index decreased at Prone130 min (p<0.05) in the ARDSp group, and at both Prone50min (p<0.05) and Prone130 min (p<0.05) in the ARDSexp group compared with Supine. Oxygen saturation of the hemoglobin and oxygen content of mixed venous blood increased at Prone50min (p<0.05) and Prone130 min (p<0.05) only in the ARDSexp group compared with Supine. These parameters did not reach statistical significance in the ARDSp group. In the ARDSp group, oxygen content of arterial blood increased only at Prone13Omjn compared with Supine (p<0.05). Intrapulmonary shunt decreased at Prone50min (<0.05) and pulmonary vascular resistance increased at Prone50min and at Prone130 min in the ARDS group compared with Supine (p<0.05).
Conclusions: We found different hemodynamic and respiratory responses to prone position in the early stages of both ARDSp and ARDSexp. These responses may differ according to the type of the insult.