Hemodynamic Effects of Postural Changes in Patients with Acute Myocardial Infarction

¹ Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles

In order to evaluate optimum patient position following acute myocardial infarction, hemodynamics were studied in 21 patients in the supine and semierect posture (70 degree head and thorax elevation with legs horizontal). None of the patients was in acute pulmonary edema or cardiogenic shock. Cardiac output (thermodilution technique) and right-sided pressure measurements were obtained with a triple lumen flow-directed balloon catheter. Following a change from the supine to semierect posture, right atrial pressure rose from an average of 6 to 9 mm Hg (p < .001), pulmonary artery systolic pressure rose from 27 to 30 mm Hg (p < .01), and left ventricular filling pressure rose from 11 to 14 mm Hg (p < .01 ). There were insignificant changes in heart rate, arterial pressure, stroke volume, cardiac output, left ventricular stroke work, and systemic and pulmonary vascular resistance. Hemodynamic responses were similar in patients with or without left ventricular failure. Thus, there were no hemodynamic advantages of either position in this group of patients. Results suggest that the patient's preference for comfort is a reasonable guide to nursing position, since there were no hemodynamic changes of importance.