608 - Effects of Intraoperative Anesthetic Medications on Postoperative Urin...

General Session: MIS-1

Presented by: B. Mayo - View Audio/Video Presentation (Members Only)


B. Mayo(1), D. Massel(1), P. Louie(1), D. Bohl(1), S. Iantorno(1), J. Ahn(1), E. Tabaraee(2), K. Singh(1)

(1) Rush University Medical Center, Orthopaedic Surgery, Chicago, IL, United States
(2) Stanislaus Orthopaedics, Modesto, CA, United States


Background information: Postoperative urinary retention (POUR) is a concerning event that may occur following routine orthopaedic surgery. The relationship between intraoperative medications and POUR following lumbar spine surgery has not been well characterized.

Objective: To identify medications that may potentially contribute to an increased likelihood of developing POUR following lumbar spinal fusion procedures.

Methods: A retrospective review was performed on a prospectively collected registry of consecutive patients that underwent a primary single-level, minimally invasive transforaminal lumbar interbody fusion during the 2009-2013 time period. Revision surgeries and multilevel procedures were excluded. POUR was defined as a bladder scan of ≥300 ml, the post-operative necessity of a straight catheterization, or a consult to urology for urinary retention. The most commonly recorded intraoperative medications were analyzed. Student's t-test, Fisher exact t-test, and the Wilcoxon rank-sum test were used to compare the use and dose-response of intraoperative medications between patients with and without POUR. A multivariate analysis was performed to analyze the differential effects of potential risk factors for developing POUR.

Results: A total of 205 consecutive patients were included in the study. Of these patients, 17% experienced POUR (n=34) as defined by the inclusion criteria delineated above. Patients with POUR had an increased duration of hospitalization. Of the commonly utilized intraoperative anesthetic medications, administration of phenylephrine and neostigmine were associated with POUR (for phenylephrine, 32.3% vs. 13.8%, p = 0.017; for neostigmine, 19.5% vs. 6.5%, p = 0.042). When testing for the effects of medication dosage on POUR, parametric analysis demonstrated an association of increasing dose of neostigmine with POUR (4.66 vs. 4.22 mg, p = 0.023). Similarly, a nonparametric analysis demonstrated an association of increasing doses of both neostigmine and phenylephrine with POUR (for neostigmine, 4.25 vs. 3.16 mg, p = 0.02; for phenylephrine, 105.88 vs. 40.64 mg, p = 0.008). Multivariate analysis identified neostigmine, phenylephrine, benign prostatic hyperplasia (BPH) as the three strongest individual risk factors for developing POUR following a single level, minimally invasive lumbar fusion.

Conclusions: Approximately 20% of patients may develop POUR following routine lumbar spine surgery. The use of certain intraoperative anesthetics such as phenylephrine and neostigmine are 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.