Cardiac cycle efficiency and dicrotic pressure variations: new parameters for fluid therapy: An observational study

During a fluid challenge, the changes in cardiac performance and peripheral circulatory tone are closely related to the position of the ventricle on the Frank-Starling curve. Some patients have a good haemodynamic response to a fluid challenge, others hardly any response. The early haemodynamic effects of a fluid challenge could predict the final response before the entire fluid volume has been administered.

BACKGROUND During a fluid challenge, the changes in cardiac performance and peripheral circulatory tone are closely related to the position of the ventricle on the Frank-Starling curve. Some patients have a good haemodynamic response to a fluid challenge, others hardly any response. The early haemodynamic effects of a fluid challenge could predict the final response before the entire fluid volume has been administered. OBJECTIVE To assess whether a multivariate logistic regression model, including pulse pressure variation (PPV), cardiac cycle efficiency (CCE), arterial elastance and the difference between the dicrotic pressure and both systolic and mean arterial pressure (SAP - P-dic and MAP - P-dic) can predict cardiac responsiveness early during a fluid challenge in comparison with the standard procedure described elsewhere. DESIGN Observational study. SETTING Elective surgical patients undergoing laparotomy, enrolled in two Italian University Hospitals. PATIENTS Fifty adult surgical patients, ventilated with a lung protective strategy, were enrolled and data from 46 were analysed. INTERVENTIONS A fluid challenge consisting of 500 ml of crystalloid infused over 10 min. MAIN OUTCOME MEASURES AND ANALYSIS The changes in CCE, arterial elastance, SAP - P-dic and MAP - P-dic were compared using analysis of variance. A multivariate logistic regression analysis utilising baseline values and the first minute measuring a variation statistically significant for the considered variables. RESULTS At baseline, PPV correctly identified 70% of patients (89% of non-responders; 42% of responders). The model, including baseline PPV, Delta CCE and Delta SAP - P-dic, P-dic, correctly identified the efficiency of fluid challenge in 87% of patients (84.2% of responders; 92.5 of non-responders) after 5 min from fluid challenge infusion. CONCLUSION In this pilot study conducted in a population of surgical patients mechanically ventilated with a V-T less than 8 ml kg(-1), a dynamic model of fluid challenge assessment, including PPV, Delta CCE and Delta SAP - P-dic, enhances the prediction of fluid challenge response after 5 min of a 10-min administration.