Cardiac Cycle Efficiency and Vasoactive-Inotropic Support After Cardiac Surgery

After open-heart surgery with cardiopulmonary bypass (CPB), many patients develop myocardial depression and vasoplegia and require vasoactive and inotropic support. High support requirement, quantified by the Vasoactive-Inotropic Score (VIS), is associated with prolonged mechanical ventilation, acute kidney injury, longer ICU stay and increased mortality. Reliable early hemodynamic markers to identify these patients are lacking.

Cardiac Cycle Efficiency (CCE), derived from arterial waveform analysis by the Pressure Recording Analytical Method (MostCare Up), reflects the energetic efficiency of the cardiovascular system, integrating contractility, arterial load and ventricular-arterial coupling. Lower CCE values have been associated with higher inotropic requirement in children after cardiac surgery, but data in adults are lacking.

In this single-center prospective observational study, hemodynamic parameters will be recorded at six time points: after induction, before CPB, 15 and 30 minutes after separation from CPB, end of surgery, and ICU admission. Patients will be classified according to maximum VIS in the first 24 postoperative hours (\<15 vs ≥15). The predictive performance of CCE at 30 minutes after CPB will be assessed by ROC analysis. Associations of CCE with lactate, duration of mechanical ventilation, ICU and hospital stay, acute kidney injury and in-hospital mortality will also be evaluated.

Adult patients undergoing elective coronary artery bypass grafting, valve surgery, or combined surgery with cardiopulmonary bypass. Hemodynamic parameters including Cardiac Cycle Efficiency will be recorded with the MostCare Up system via the routinely placed radial arterial catheter. No study-specific intervention will be applied.

Time frame: First 24 hours after ICU admission

Area under the ROC curve of Cardiac Cycle Efficiency measured 30 minutes after separation from cardiopulmonary bypass for predicting maximum Vasoactive-Inotropic Score (VISmax) ≥15. VISmax is the highest hourly VIS during the first 24 hours after ICU admission.

Time frame: First 24 hours after ICU admission

ROC analysis of CCE at 15 minutes after bypass and mean of 15- and 30-minute CCE values for predicting VISmax ≥15.

Time frame: At intensive care unit admission and 6 and 24 hours after admission.

The Vasoactive-Inotropic Score (VIS) will be assessed at intensive care unit admission and at 6 and 24 hours after admission. VIS will be calculated as dopamine + dobutamine + (100 × epinephrine) + (100 × norepinephrine) + (50 × levosimendan) + (10,000 × vasopressin). Drug doses are expressed in µg/kg/min, except vasopressin, which is expressed in units/kg/min. The minimum score is 0, and there is no fixed maximum score. Higher scores indicate worse outcomes, reflecting greater vasoactive and inotropic support requirements; lower scores indicate better outcomes, reflecting lower support requirements.

Time frame: 24 hours

Lactate (mmol/L) at ICU admission, 6 and 24 hours; lactate clearance in the first 6 hours (%).

Time frame: Until hospital discharge, up to 30 days

All-cause death during hospital stay.

Time frame: Until hospital discharge, up to 30 days

Time from ICU admission to extubation (hours) and need for reintubation.

The Value of Cardiac Cycle Efficiency After Cardiopulmonary Bypass in Predicting Vasoactive-Inotropic Support Requirement (VIS) in the First 24 Hours in Open-Heart Surgery: A Prospective Observational Cohort Study