Structured Hemodynamic Assessment to Guide Care After Cardiac Surgery

Postoperative management following cardiac surgery requires the integration of clinical and hemodynamic variables to guide individualized treatment. Important decisions include fluid balance management, the use of vasoactive medications, inotropic support, pulmonary vasodilators, and more. Combining point-of-care ultrasound (POCUS) and advanced hemodynamic monitoring may provide complementary information by assessing fluid tolerance, fluid responsiveness, and potential mechanisms underlying hemodynamic abnormalities.

Fluid tolerance refers to the ability to receive additional fluid without developing or worsening clinically significant congestion. The Venous Excess UltraSound (VExUS) score evaluates systemic venous congestion using inferior vena cava diameter and hepatic, portal, and intrarenal venous Doppler. Abnormal VExUS findings have been associated with adverse outcomes following cardiac surgery; however, whether incorporating this information into a structured decision-support strategy influences clinical management remains uncertain.

Fluid responsiveness refers to the capacity of cardiac output to increase following an increase in cardiac preload. In this study, it will be assessed using continuous estimated cardiac output (eCO) obtained with the Swan-Ganz IQ catheter and HemoSphere Alta monitor during a passive leg raise (PLR) maneuver. Fluid responsiveness will be defined as an increase in eCO of at least 10%, with return to baseline after the maneuver. Combining fluid tolerance and fluid responsiveness assessments may help identify patients who could benefit from fluid administration while identifying those at risk of adverse effects from fluid accumulation.

USE-the-FORCE-in-CVICU is a multicenter pilot randomized controlled trial enrolling 75 adult cardiac surgery patients at the Centre hospitalier de l'Université de Montréal and the Montreal Heart Institute. Participants will be randomized in a 2:1 ratio to a structured hemodynamic assessment strategy or standard care. A baseline ultrasound examination will be performed before surgery, followed by ultrasound and hemodynamic assessments in both groups upon intensive care unit (ICU) admission and on postoperative day 1.

In the intervention group, an expert will provide a structured report of the assessment to the treating team within two hours of each postoperative assessment. The report will describe fluid tolerance and fluid responsiveness, contextual interpretation of relevant findings, and individualized therapeutic considerations. Recommendations will be non-prescriptive, and all treatment decisions will remain at the discretion of the treating team. In control participants, the structured hemodynamic assessment will also be performed, but the findings will not be disclosed to the treating team unless disclosure is necessary to protect participant safety. Control participants will receive standard postoperative care. Participants and outcome assessors will be blinded to allocation; treating clinicians cannot be blinded to receipt of the reports.

The trial has two co-primary objectives. The proof-of-concept objective is to evaluate the impact of the additional hemodynamic information on clinical management using a physician-reported five-point usefulness scale. The feasibility objective is to determine whether all required study procedures can be completed in more than 80% of participants, including planned assessments, timely report transmission in the intervention group, and outcome data collection.

Secondary outcomes will include fluid balance and diuretic use during the first 72 hours after randomization or until ICU discharge, whichever occurs first, and inotropic support and inhaled pulmonary vasodilator use during the first 72 hours. Kidney outcomes will include acute kidney injury incidence and severity using serum creatinine-based KDIGO criteria, kinetic estimated glomerular filtration rate during the first seven days after randomization, and classification of acute kidney injury as transient or persistent.

Additional outcomes will include time alive and free of vasopressors, mechanical ventilation, ICU care, or hospitalization; kidney replacement therapy; and cumulative time with perioperative organ dysfunction or death through postoperative day 28. Operative mortality will include deaths during the surgical hospitalization and deaths after discharge within 30 postoperative days. Qualitative feedback will explore physicians' perspectives on the assessment's influence on management and barriers to acting on the findings.

Exploratory analyses will compare PLR-induced changes in corrected carotid flow time with simultaneous changes in Swan-Ganz IQ-derived eCO, describe right ventricular pressure waveform patterns and their relationship with VExUS grade, and examine renal and splenic arterial Doppler indices in relation to acute kidney injury subtypes.