Abstract
BACKGROUND: Patients with end-stage renal disease on hemodialysis (HD) undergoing cardiac surgery face increased risks. Mixed venous saturation (SvO(2)) is an important parameter representing the systemic oxygen supply-demand balance. However, interpreting SvO(2) in HD patients may be challenging due to arteriovenous fistulas. The literature on these issues is lacking. This study aimed to investigate the change in SvO(2) in HD patients by comparing those in non-HD patients perioperatively. METHODOLOGY: From April 1, 2019, to March 31, 2020, 39 patients undergoing cardiac surgery with pulmonary artery catheters, 18 with and 21 without HD, were identified. The cardiac index (CI) and SvO(2) were extracted from patient records, and the oxygen delivery index (DO(2)I) was calculated before surgery (T0), on intensive care unit (ICU) admission (T1), 24 hours (T2), and 48 hours (T3) after ICU admission. A linear mixed effects model was applied for repeated measures analyses. RESULTS: T0 CI was significantly higher in the HD group (2.5 ± 0.5 vs. 2.0 ± 0.5 L/minute/m(2), mean ± SD, P = 0.003) and increased significantly over time in both groups, without an interaction effect (P for interaction = 0.12). T0 SvO(2) did not differ between groups (72 ± 10% vs. 72 ± 5%, P = 0.97) and decreased over time, more evidently in the non-HD group (P for interaction = 0.016). DO(2)I was similar in both groups perioperatively. CONCLUSIONS: SvO(2) tended to be higher in the HD group perioperatively. If SvO(2) in HD patients is similar to that in non-HD patients, this may mean that the oxygen supply-demand balance is disturbed.