Risk Factors for Postoperative Ileus in Patients Undergoing Spine Surgery

Study Design: Retrospective Cohort Study Objectives: Postoperative ileus (POI) is a common complication following elective spinal surgeries. The aim of this study was to determine the incidence of POI and identify demographic and surgical risk factors for developing POI after elective instrumented fusion of the thoracolumbar spine. Methods: The University of Utah Institutional Review Board (IRB) approved this retrospective study. The study does not require informed consent given the data reviewed was deidentified and collected in accordance with the institution’s standard of care. A designated IRB committee determined that study is exempt under exemption category 7. IRB approval number 00069703. Patients undergoing instrumented thoracolumbar fusion for one or more levels were retrospectively identified from an internal spine surgery database. Cases performed for trauma, infection, or tumors were excluded. Demographics, medical comorbidities, surgical variables, and opioid medication administration (morphine milligram equivalents, MME) were abstracted from the electronic medical record. Univariate analysis was used to identify variables associated with POI. These variables were then tested for independent association with POI using multivariate logistic regression. Results: 418 patients were included in the current study. The incidence of POI was 9.3% in this cohort. There was no significant relationship between development of POI and patient age, gender, BMI, diabetes mellitus, thyroid dysfunction, lung disease, CKD, GERD, smoking status, alcohol abuse, anemia, or prior abdominal surgery. Univariate analysis demonstrated significant association between POI and fusion ≥7 levels compared to fusions of fewer levels (P =.001), as well as intraoperative sufentanil compared to other opioids (35.9% vs 20.1%, P =.02). POI was not significantly associated with total intraoperative MME, approach, use of interbody cage, or osteotomy. Multivariate logistic regression confirmed total 24-hour postoperative MME as an independent risk factor for POI (OR 1.004, P =.04), however, intraoperative sufentanil administration was not an independent risk factor for POI when controlling for other variables. Conclusions: This retrospective cohort study demonstrates that greater postoperative MME is an independent risk factor for POI after thoracolumbar spine fusion when accounting for demographic, medical, and surgical variables with multiple logistic regression. Prospective studies are warranted to evaluate clinical measures to decrease the risk of POI among patients undergoing instrumented thoracolumbar spinal fusions.