THE SYSTOLIC BLOOD-PRESSURE VARIATION AS AN INDICATOR OF PULMONARY CAPILLARY WEDGE PRESSURE IN VENTILATED PATIENTS

Animal data have suggested that the systolic pressure variation (SPV) noted during positive pressure ventilation may be a sensitive indicator of hypovolaemia. The aim of this study was to correlate the SPV with the pulmonary capillary wedge Pressure (PCWP) in a heterogeneous group of ICU patients on volume-cycled ventilation. Three hundred data sets were collected on 226 patients. The correlation coefficient between the SPV and PCWP for the first half of the data set was -0.84 (P < 0.001). The linear regression formula from this data set was: PCWP = 20-(SPV*0.7). Using this formula the predicted PCWP was then correlated with the measured PCWP using the second half of the data base. The correlation coefficient was 0.87 (P < 0.001). The correlation coefficient between the SPV and PCWP for the entire data base (300 observations) was -0.86 (P < 0.001). It is concluded that analysis of the arterial pressure tracing may be useful in estimating the pulmonary capillary wedge pressure in ventilated patients.