Hemodilution in high-risk cardiac surgery: Laboratory values, physiological parameters, and outcomes

Area of Science:

• Cardiovascular Surgery
• Anesthesiology
• Transfusion Medicine

Background:

• Acute normovolemic hemodilution (ANH) is a blood conservation strategy used in cardiac surgery.
• Concerns about hemodynamic instability and organ injury limit ANH use in complex procedures.
• Physiological parameters during ANH in complex cardiac surgeries remain under-described.

Purpose of the Study:

• To evaluate the safety and physiological effects of ANH in high-risk cardiac surgery patients.
• To compare laboratory and physiological parameters between patients undergoing ANH and non-ANH controls.
• To assess the impact of ANH on intraoperative and postoperative outcomes.

Main Methods:

• Observational cohort study of 169 patients undergoing complex thoracic aortic repair, valve procedures, or concomitant CABG.
• Patients receiving allogeneic blood were excluded.
• Comparison of ANH (N=66) versus non-ANH controls (N=103), with ANH involving blood removal and reinfusion around cardiopulmonary bypass.

Main Results:

• ANH group received more albumin and vasopressors; urine output was similar.
• Cerebral oximetry (rSO2) values were comparable pre/post-hemodilution but discretely lower during bypass in the ANH group.
• No significant differences in lactic acid, extubation times, ICU stay, kidney injury, stroke, or infection were observed.

Conclusions:

• ANH appears to be a safe blood conservation technique in complex cardiac surgeries.
• The study supports wider acceptance of ANH protocols in high-risk cardiac procedures.
• No increased risk of organ injury or adverse outcomes was demonstrated with ANH.