Analysis of systemic vascular resistance after cardiac surgery: a retrospective cohort study

Background: Hypotension is a dangerous vital sign frequently encountered during the postoperative management of cardiac surgery. However, factors influencing the systemic vascular resistance index (SVRI), which is strongly related to hypotension, are not well understood. This study evaluated the characteristics of the SVRI according to the type of cardiac surgery. Methods: During this retrospective cohort study, we used the clinical data of patients who underwent cardiac surgery at Asahi General Hospital from April 2014 to August 2020. We analyzed their vital signs during the first 12 hours after surgery and evaluated the differences in vital signs among four types of surgery: mitral valve (MV) surgery; aortic valve (AV) surgery; coronary artery bypass grafting (CABG); and thoracic aorta (TA) surgery. Data were compared among these four groups using one-way analysis of variance every 2 hours postoperatively. Those with significant differences were further compared using the post hoc Tukey-Kramer test. Results: A total of 493 patients participated in this study. Overall, the SVRI decreased within 2 hours after the cardiopulmonary bypass surgery. The SVRI after MV surgery was significantly lower than that after other surgery types. The doses of inotropes used for MV surgery and TA surgery were significantly greater than those used for the other surgery types. Conclusions: The SVRI changes significantly after cardiac surgery and may decrease, especially after MV surgery. For better results, it is necessary to consider the differences in the SVRI that are associated with different types of cardiac surgery.