title: Risk factors for ischemic optic neuropathy after cardiopulmonary bypass: a matched case/control study.
abstract: Visual loss (acuity or field) secondary to ischemic optic neuropathy (ION) is a rare but devastating complication of cardiac surgery involving cardiopulmonary bypass (CPB). We determined clinical features and risk factors for ION by a retrospective time-matched, case-control study. ION was identified in 17 (0.06%) patients out of 27,915 patients who underwent CPB between January 1, 1976, and December 31, 1994. For each ION patient, two patients who underwent CPB exactly 2 wk before the ION patient were selected as controls. Data were analyzed by using conditional logistic regression with the 1:2 matched-set feature of 17 cases and 34 controls. Two-tailed P values < or =0.05 were considered significant. From bivariate analysis, smaller minimum postoperative hemoglobin concentration (odds ratio [OR] = 1.9, P = 0.047) and the presence of atherosclerotic vascular disease (OR = 7.0, P = 0.026) were found to be independently associated with ION after CPB, as were smaller minimum postoperative hemoglobin concentration (OR = 2.2, P = 0.027) and preoperative angiogram within 48 h of surgery (OR = 7.2, P = 0.042). In ION patients, 13 (76.5%) of 17 experienced a minimum postoperative hemoglobin value of < 8.5 g/dL, whereas only 14 (41.2%) of 34 control patients experienced values < 8.5 g/dL.
  
  
  CONCLUSIONS
  Patients with clinically significant vascular disease history or preoperative angiogram may be at increased risk for ischemic optic neuropathy after cardiac surgery, especially if the hemoglobin remains low in the postoperative period.
authors.affiliation: Department of Anesthesiology, Mayo Graduate School of Medicine, Rochester, Minnesota 55905, USA. nuttall.gregory@mayo.edu
authors.forename: G A
authors.initials: GA
authors.lastname: Nuttall
authors.forename: J A
authors.initials: JA
authors.lastname: Garrity
authors.forename: J A
authors.initials: JA
authors.lastname: Dearani
authors.forename: M D
authors.initials: MD
authors.lastname: Abel
authors.forename: D R
authors.initials: DR
authors.lastname: Schroeder
authors.forename: C J
authors.initials: CJ
authors.lastname: Mullany
mesh_terms: D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000150:complications; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018917:Optic Neuropathy, Ischemic / Q000209:etiology*; D011183:Postoperative Complications; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D006454:Hemoglobins