Comparison of pulmonary artery pressure measurements in the supine and 60 degrees lateral positions

Abstract

Pulmonary artery pressure monitoring, with the patient in both the supine and lateral positions, is an essential element in the assessment of critically ill patients. Previous work offers conflicting results regarding the accuracy of measurements obtained with the patient in the lateral position. The purpose of this study was to determine if accurate pulmonary artery pressure measurements can be obtained in the cardiac surgical patient. Thirty-five patients underwent repositioning between the supine and both the left and right 60 degrees lateral position while being mechanically ventilated and then breathing spontaneously. Pulmonary artery pressure measurements were recorded prior to, two minutes following and ten minutes following repositioning. Despite some variation in results the pulmonary capillary wedge pressure measurement was reliable ten minutes after repositioning in both the spontaneously breathing and mechanically ventilated patient. Other pulmonary artery pressure measurements were not so reliable in the lateral position. This study concludes that clinical practitioners can obtain accurate pulmonary capillary wedge pressure measurements in post-operative cardiac surgical patients positioned in either the left or right 60 degrees lateral position. Further research is however required, with larger numbers from all sub-groups of the critical care population. Physiological and pathophysiological characteristics which preclude reliable pulmonary artery pressure measurements need to be identified.