Assessment of changes in cardiac index with calibrated pulse contour analysis in cardiac surgery: A prospective observational study

Abstract

Objectives: To assess the trending ability of calibrated pulse contour cardiac index (CIPC) monitoring during haemodynamic changes (passive leg raising [PLR] and fluid loading) compared with transpulmonary thermodilution CI (CITD).

Method: Seventy-eight mechanically-ventilated patients admitted to intensive care with calibrated pulse contour following cardiac surgery were prospectively included and investigated during PLR, and after fluid loading. Fluid responsiveness was defined as a≥15% CITD increase after a 500ml bolus. Areas under the empiric receiver operating characteristic curves (ROCAUC) for changes in CIPC (ΔCIPC) during PLR to predict fluid responsiveness and after fluid challenge to predict an increase at least 15% in CITD after fluid loading were calculated.

Results: Fifty-five patients (71%) were classified as responders, 23 (29%) as non-responders. ROCAUC for ΔCIPC during PLR in predicting fluid responsiveness, its sensitivity, specificity, and percentage of patients within the inconclusive class of response were 0.67 (95% CI=0.55-0.77), 0.76 (95% CI=0.63-0.87), 0.57 (95% CI=0.34-0.77) and 68%, respectively. Bias, precision and limits of agreements and percentage error between CIPC and CITD after fluid challenge were 0.14 (95% CI: 0.08-0.20), 0.26, -0.37 to 0.64 l min(-1)m(-2), and 20%, respectively. The concordance rate was 97% and the polar concordance at 30° was 91%. ROCAUC for ΔCIPC in predicting an increase of at least 15% in CITD after fluid loading was 0.85 (95% CI: 0.76-0.92).

Conclusion: Although ΔCIPC after fluid loading could track the direction of changes of CITD and was interchangeable with bolus transpulmonary thermodilution, PLR could not predict fluid responsiveness in cardiac surgery patients.

Keywords: Arterial pressure; Cardiac surgery; Fluid responsiveness; Passive leg raising; Pulse contour analysis.