Postoperative Vasoplegic Syndrome Is Associated With Impaired Endothelial Vasomotor Response in Cardiac Surgery: A Prospective, Observational Study

Objectives: Vasoplegic syndrome (VS) affects up to 30% of cardiac surgery patients. Onset of VS may be associated with overproduction of nitric oxide (NO). The response of the brachial artery to NO can be assessed using flow-mediated vasodilation (FMD). The aim of this study was to assess brachial artery diameter and FMD response immediately after cardiac surgery.

Design: Prospective, observational study.

Setting: Single-center study in a tertiary teaching hospital.

Patients: Patients older than 18 years undergoing elective cardiac surgery with cardiopulmonary bypass who provided informed consent.

Interventions: Brachial artery diameter and FMD response were measured before cardiac surgery and just after surgery on admission to the intensive care unit. Patients were screened for VS for the following 48 hours.

Results: Eleven (39%) of the 28 patients included in the study developed VS. Brachial artery diameter and FMD differed between VS and non-VS patients. On intensive care unit admission, mean (± standard deviation) brachial artery diameter was greater in VS patients than in non-VS patients (3.9 ± 0.7 mm v 3.0 ± 0.8 mm, respectively; p = 0.002). Similarly, the FMD response after surgery was greater in VS patients than in non-VS patients (42% ± 8% v 31% ± 1%, respectively; p = 0.014). Brachial artery diameter and FMD response after surgery were both predictive of VS, with an area under the curve (95% confidence interval) of 0.850 (0.705-0.995) (p = 0.002) and 0.755 (0.56-0.95) (p = 0.047), respectively.

Conclusion: Cardiac surgery with cardiopulmonary bypass appears to alter the NO-mediated endothelial vasomotor response.