Preferential Flow Patterns of Injectate in Epidural and Inadvertent Subdural Anesthesia: Exploring the Hemodynamic Stability of High-Level Epidural, Subdural and Combined Epidural-Subdural Blocks in Relation to ASA Class

Hemodynamic stability was maintained in the subdural and combined epidural-subdural groups compared to the epidural group in ASA I to III patients. However, epidural anesthesia showed better hemodynamic outcomes for ASA class above III. High-level epidural and subdural anesthesia primarily induced posterior diffusion, resulting in minimal anterior sympathetic block while preserving stability. These findings suggest that epidural anesthesia may be a viable alternative for spinal surgeries and applicable to other procedures for patients with high ASA classifications.