title: The Use of Somatosensory Evoked Potentials to Determine the Relationship Between Intraoperative Arterial Blood Pressure and Intraoperative Upper Extremity Position-Related Neurapraxia in the Prone Surrender Position During Spine Surgery: A Retrospective Analysis.
abstract: BACKGROUND
  Peripheral nerve injury is a significant perioperative problem. Intraoperative position-related neurapraxia may indicate impending peripheral nerve injury and can be detected by changes in somatosensory evoked potentials (SSEP). The purpose of this retrospective analysis of spine surgeries performed under general anesthesia with SSEP monitoring was to determine the relationship between intraoperative mean arterial blood pressure (MAP) and intraoperative upper extremity position-related neurapraxia in the prone surrender (superman) position.
  
  
  METHODS
  We reviewed a computerized database of spine surgeries performed on adult patients in the prone surrender position. The authors reviewed intraoperative SSEP monitoring reports to identify the patients who developed intraoperative upper extremity position-related neurapraxia (case group) and patients who did not (control group). Propensity matching was performed to derive 2 demographically matched groups. Preoperative and intraoperative variables were included in the univariate Cox regression analysis of risk factors associated with neurapraxia. Multivariate Cox regression models were used to identify the independent risk factors.
  
  
  RESULTS
  One hundred fifty-two patients were included in the analysis. The case group included 32 patients, whereas the control group included 120 matched patients. Intraoperative MAP <55 mm Hg for a total duration of ≥5 minutes was an independent risk factor associated with a greater incidence of upper extremity position-related neurapraxia compared with a duration of <5 minutes with MAP <55 mm Hg (hazard ratio, 3.43; confidence interval, 1.445-8.148; P = 0.0052). Intraoperative MAP >80 mm Hg for a total duration of >55 minutes was an independent predictor associated with a lower incidence of neurapraxia compared with a total duration ≤55 minutes (hazard ratio, 0.341; confidence interval, 0.163-0.717; P = 0.0045).
  
  
  CONCLUSIONS
  In this study, we identified the changes in intraoperative MAP as independent predictors associated with upper extremity position-related neurapraxia in the prone surrender position under general anesthesia.
authors.affiliation: From the Department of Anesthesiology, Temple University School of Medicine, Philadelphia, Pennsylvania.
authors.forename: Ihab
authors.initials: I
authors.lastname: Kamel
authors.forename: Huaqing
authors.initials: H
authors.lastname: Zhao
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Koch
authors.forename: Neil
authors.initials: N
authors.lastname: Brister
authors.forename: Rodger E
authors.initials: RE
authors.lastname: Barnette
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D062186:Arterial Pressure; D016009:Chi-Square Distribution; D016208:Databases, Factual; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D019637:Orthopedic Procedures / Q000009:adverse effects*; D056888:Patient Positioning / Q000009:adverse effects*; D059348:Peripheral Nerve Injuries / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D011237:Predictive Value of Tests; D016684:Prone Position; D057216:Propensity Score; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013131:Spine / Q000601:surgery*; D013997:Time Factors; D034941:Upper Extremity / Q000294:innervation*