Pre-ejection period is a reliable parameter to estimate cardiac preload in a hemorrhagic shock

Introduction

We have already demonstrated that in mechanically ventilated patients, the respiratory change in the pre-ejection period (ΔPEP) is a reliable dynamic index for the prediction of increase in cardiac output after volume infusion [1]. However, in an animal study, Kubitz and colleagues showed that the pre-ejection period is not sensitive to the changes in intravascular volume status [2].

Methods

This study investigated the influence of changes in intravascular volume status on ΔPEP. In 17 pigs, ECG, arterial pressure and cardiac output derived from a Swan-Ganz catheter were recorded. Measurements were performed during normovolaemic conditions, after haemorrhage (25 ml/kg) and following re-transfusion (25 ml/kg) with constant tidal volume (10 ml/kg) and respiration rate (15/minute).

Results

At baseline, respiratory changes in pulse pressure (PPV) and ΔPEP were both <12%. PPV significantly correlated with ΔPEP (r = 0.96, P < 0.001). Volume loss induced by haemorrhage increased PPV and ΔPEP. Moreover, during this state, PPV correlated with ΔPEP with a significant correlation coefficient (r = 0.88, P < 0.001). Retransfusion significantly decreased PPV and ΔPEP and PPV significantly correlated with ΔPEP (r = 0.94, P < 0.001) (Figure 1).

Figure 1

Box plot representing pulse pressure variations (PPV) (%) and pre-ejection period variations (ΔPEP) (%) at the three times of the protocol. ^§P < 0.05, ^†P < 0.05.

Conclusions

Available correlations between PPV and ΔPEP at each time of the study were observed, meaning that ΔPEP is a reliable parameter to estimate the changes in intravascular volume status.