Effects of change of position on pulmonary artery and pulmonary capillary wedge pressures in mechanically ventilated patients

This study investigated the effect of the position of the head of the bed on pulmonary artery (PA) and pulmonary capillary wedge (PCW) pressures. A series of four measurements of PA and PCW pressures were obtained with the head of the bed at four levels (0, 20, 45, and 60 degrees). The order of treatments was prerandomized and preassigned. At each level the transducer was leveled to the phlebostatic level and zeroed to atmospheric pressure, and the pressure module calibrated. All 17 subjects studied were mechanically ventilated and had respiratory variation in their PA waveforms. Measurements were done at end-expiration. The data were analyzed using analysis of variance and repeated measures statistic. No significant differences were found among the patient positions (p<0.05) in pulmonary artery systolic, diastolic, and wedge pressures. Because reliable measurements of PA and PCW pressures can be obtained in positions other than the flat recumbent position, patients should be positioned in whatever position is optimal for patient care without the need to alter this position for hemodynamic monitoring.