Effects of Intraoperative Anesthetic Medications on Postoperative Urinary Retention After Single-Level Lumbar Fusion

Study Design.Retrospective cohort analysis.Objective.The aim of the study was to identify medications that may potentially contribute to developing postoperative urinary retention (POUR) after lumbar spinal fusion procedures.Summary of Background Data.POUR is a concerning event that may occur after routine orthopedic surgery. The relation between intraoperative medications and POUR after lumbar spine surgery has not been well characterized.Methods.A prospectively maintained database of patients who underwent a primary single-level, minimally invasive transforaminal lumbar interbody fusion between 2009 and 2013 was reviewed. POUR was defined as a bladder scan of 300mL or higher, the postoperative necessity of a straight catheterization, or a urology consult for urinary retention. The use and dose-response of intraoperative medications between patients with and without POUR were compared. Potential risk factors for developing POUR were analyzed using multivariate analysis.Results.A total of 205 patients were included in the study, 17% of whom experienced POUR (n=34). Administration of phenylephrine and neostigmine was associated with POUR (phenylephrine: 32.3% vs. 13.8%, P=0.017; neostigmine: 19.5% vs. 6.5%, P=0.042). Parametric analysis demonstrated an association of increasing dose of neostigmine with POUR (4.66 vs. 4.22mg, P=0.023). Similarly, a nonparametric analysis demonstrated an association of increasing doses of both neostigmine and phenylephrine with POUR (neostigmine: 4.25 vs. 3.16mg, P=0.02; phenylephrine: 105.88 vs. 40.64mg, P=0.008).Conclusion.Approximately 20% of patients may develop POUR after routine lumbar spine surgery. The use of certain intraoperative anesthetics such as phenylephrine and neostigmine is strongly associated with the development of POUR postoperatively. This finding suggests that there may be modifiable anesthetic risk factors to prevent the development of POUR in patients undergoing lumbar spine surgery. Future prospective, controlled studies specifically addressing these findings could lead to improved patient care and decreased healthcare costs.Level of Evidence: 4