Pathogenesis of respiratory failure (ARDS) after hemorrhage and trauma: II. Cardiorespiratory patterns after development of ARDS.

Abstract

Hemodynamic and oxygen transport variables were studied in a series of 60 patients who sustained adult respiratory distress syndrome (ARDS) from hemorrhage and trauma; measurements were made during the period of their ARDS and in survivors after their recovery from ARDS. In general, cardiac index (CI) and myocardial performance were increased over normal values; they were greater in trauma patients than in hemorrhage patients and greater in the survivors than in nonsurvivors. The mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance index (PVRI) were high in all groups. Blood volume and hemoglobin (Hgb) concentrations were reduced especially in the nonsurviving hemorrhage patients; hemoglobin saturation (SaO2) and oxygen tension (PaO2) were low initially, but usually responded to therapy; oxygen consumption (VO2) was normal or high in all groups, and was greater in survivors than in nonsurvivors, and greater in trauma than in hemorrhage. Thus, the patient with post-traumatic ARDS has circulatory and metabolic needs which are greater than normal values defined by values from healthy unstressed volunteers and also somewhat greater than hemorrhage and trauma patients without ARDS. Optimal blood volume, hemodynamic and oxygen transport values defined by the survivor's values as well as the standard respiratory care are recommended as goals for preventive or ealy therapy of these patients. Volume therapy should be given provided it does not elevate the pulmonary arterial wedge pressure (WP) above 18 mm Hg to avoid overloading the pulmonary vascular bed and causing pulmonary edema.