Fluid responsiveness in patients following major surgery

Introduction

The aim of the study was to see how many patients were fluid responders on arrival in the ICU and to evaluate the performance of dynamic preload indices in predicting fluid responsiveness in fully sedated and mechanically ventilated patients. The following indices were studied: pulse pressure variation (PPV), stroke volume variation (SVV) and systolic pressure variation (SPV).

Methods

Patients were monitored with the LiDCOTMplus and received a fluid challenge (250 ml boluses of colloid in 5 min) to ascertain fluid responsiveness. Patients in which a fluid challenge produced a 10% increase in stroke volume were considered fluid responders and thus the fluid challenge was repeated according to the unit protocol [1]. In fully mechanically ventilated patients, the PPV, SVV and SPV were recorded and receiver operating characteristic (ROC) analysis was performed.

Results

Thirty-three patients (mean age 64 years; SD ± 13.80; mean BMI 27.34; 16 female and 17 male) were included; 23 patients were on spontaneous ventilation and 10 were totally fully ventilated with a mean tidal volume of 8 ml/kg and positive end-expiratory pressure of 5 cmH₂O. Thirteen patients (40%) were responders, of which five were mechanically ventilated. Areas under the ROC curve (AUC) for dynamic predictors of fluid responsiveness were examined for ventilated patients; for PPV, AUC = 0.65 with SD ± 0.14, P = 0.28 showing a sensitivity of 67% and a specificity of 79% for a cutoff value of 14%; for SVV, AUC = 0.73 with SD ± 0.14, P = 0.1 showing a sensitivity of 67% and a specificity of 74% for a cutoff value of 9%; and for SPV, AUC = 0.74 with SD ± 0.12, P = 0.09 showing a sensitivity of 67% and a specificity of 86% for a cutoff value of 8%.

Conclusion

A high percentage of patients were fluid responsive on arrival in the ICU following major surgery (40%). The PPV, SVV and SPV have a potential to predict fluid responsiveness in mechanically ventilated patients.