Intraoperative and postoperative fluid administration is associated with transfusion in open arteriovenous malformation and aneurysm surgery

Background Red blood cell transfusion to manage hemodynamic instability or blood loss during and after open cerebrovascular surgery has been associated with postoperative complications, making transfusion avoidance an important quality-improvement target. Iatrogenic hemodilution from liberal crystalloid administration may contribute to perioperative anemia, but its relevance in open aneurysm and arteriovenous malformation (AVM) surgery is poorly defined. We investigated factors associated with receiving intraoperative and postoperative transfusion in these open cerebrovascular procedures and the association between transfusion and early postoperative outcomes. Methods In this single-center retrospective propensity-matched cohort study, patients who underwent open aneurysm or AVM surgery and received an intraoperative or postoperative red blood cell transfusion were matched 1:1 with non-transfused controls. Perioperative variables—including intraoperative and 72-h postoperative fluid administration, estimated blood loss, physiological parameters, comorbidities, and laboratory values—were compared using univariate analysis, and multivariable Firth logistic regression was used to evaluate factors associated with transfusion. To address the temporal relationship between fluid and transfusion, a time-anchored analysis compared pre-transfusion fluids received with fluids received by controls to the same time point. Intensive care unit and hospital length of stay were evaluated. Results Fifty-six patients (28 transfused, 28 controls) were analyzed. Transfused patients received more intravenous fluid in the first 72 postoperative hours (13.1 ± 4.4 vs 9.8 ± 4.6 L, p = 0.009), and transfusion percentage increased across fluid quartiles (21 %, 50 %, 64 %, and 64 %; p for trend = 0.020). Transfused patients also had a higher American Society of Anesthesiologists (ASA) class and longer operative duration. Similarly, in the time-anchored analysis, receiving more fluids was associated with transfusion (adjusted OR 1.28 per L, 95 % CI 1.14–1.45), including after additional adjustment for ASA class (OR 1.23, 95 % CI 1.08–1.40). Intensive care unit and hospital stays were longer among transfused patients, but the differences were not statistically significant. Conclusions Greater fluid administration perioperatively was associated with receiving intraoperative or postoperative transfusion after open aneurysm and AVM surgery. These findings are consistent with, but do not establish, a contribution of iatrogenic hemodilution, and they support prospective evaluation of fluid management.