Cardiac Cycle Efficiency and Dicrotic Pressure Variations: New Parameters for Fluid Therapy: An Observational Study

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 - Pdic and MAP - Pdic) 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 - Pdic and MAP - Pdic 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, ΔCCE and ΔSAP - Pdic, 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 VT less than 8 ml kg, a dynamic model of fluid challenge assessment, including PPV, ΔCCE and ΔSAP - Pdic, enhances the prediction of fluid challenge response after 5 min of a 10-min administration.

Trial Registration: ACTRN12616001479493.