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.