Pre-ejection period variations predict the fluid responsiveness of septic ventilated patients

Objectives: In septic patients with acute circulatory failure, reliable predictors of fluid responsiveness are needed at the bedside. We hypothesized that the respiratory change in pre-ejection period (Delta PEP) would allow the prediction of changes in cardiac index following volume administration in mechanically ventilated septic patients. Design: Prospective clinical investigation. Setting: A ten-bed hospital intensive care unit. Patients: Patients admitted after septic shock equipped with an arterial catheter. Interventions: Pre-ejection period (PEP)-defined as the time interval between the beginning of the R wave on the electrocardiogram and the upstroke of the radial arterial pressure curve (PEPKT) or the pulse plethysmographic waveforms (PEPPLET)-and cardiac index (transthoracic echocardiography-Doppler) were determined before and after volume infusion of colloid (8 mL.kg(-1)). Delta PEP (%) was defined as the difference between expiratory and inspiratory PEP divided by the mean of expiratory and inspiratory values. Respiratory changes in pulse pressure (Delta PP) was also measured. Measurements and Main Results: Twenty-two volume challenges were done in 20 deeply sedated patients. Delta PEPKT, Delta PEPPLET, and Delta PP (measured in all patients) before volume expansion were correlated with cardiac index change after fluid challenge (r(2)=.73, r(2)=.67, and r(2)=.70, respectively, p<.0001). Patients with a cardiac index increase induced by volume expansion >= 15% and <15% were classified as responders and nonresponders, respectively. Receiver operating characteristic curves showed that the threshold Delta PP value of 17% allowed discrimination between responder/non responder patients with a sensitivity of 85% and a specificity of 100%. For both Delta PEPKT and Delta PEPPLET, the best threshold value was 4% with a sensitivity-specificity of 92%-89% and 100%-67%, respectively. Conclusions: The present study found Delta PEPKT and Delta PEPPLET to be as accurate as Delta PP in the prediction of fluid responsiveness in mechanically ventilated septic patients.