Objectives: Societal guidelines recommend initiating systemic heparinization >1 hour after neuraxial anesthesia (NA) to reduce the risk of spinal hematoma (SH) formation. This study was designed to assess anesthesiologists' adherence to these guidelines in the context of vascular surgeries and compare compliance among Canadian tertiary hospitals. The incidence of SH within the studied period was also evaluated (secondary outcome).
Design: Retrospective chart review between April 2012 and April 2023.
Setting: Canadian academic tertiary centers.
Participants: Vascular surgery patients (>18 years old) undergoing femoral-femoral bypass, femoral-tibial bypass, and endovascular aneurysm repair surgeries under NA.
Interventions: NA with subsequent systemic heparinization.
Measurements and main results: In total, 877 patients were analyzed. Among them, 41.2% received intravenous heparin <60 minutes and 26.3% <45 minutes after NA. There was significant variability in guideline compliance between participating institutions. Compliance also varied with the type of surgical procedure. The interval was shortest at all centers for endovascular aneurysm repairs, with 63.3% of patients receiving heparin <60 minutes and 41.2% <45 minutes after NA. No cases of clinically significant SH were reported. Given the zero numerator, the risk of SH was estimated at ≤0.8% and ≤1.3% (frequentist method) or ≤0.3% and ≤0.34% (Bayesian approach), stated with 95% and 99% confidence or credibility, respectively.
Conclusions: Despite significant variability among participating institutions, anesthesiologists at all centers often overlooked societal guidelines and administered systemic heparin before the 1-hour recommendation following NA. Guideline compliance also varied across the surgical procedures studied. No cases of SH were reported.
Keywords: neuraxial anesthesia; retrospective analysis; spinal hematoma; systemic heparin; vascular surgery.
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