title: Cerebral desaturation during shoulder arthroscopy: a prospective observational study.
abstract: BACKGROUND
  Patients undergoing arthroscopic shoulder surgery in the beach chair position may be at increased risk for serious neurocognitive complications as a result of cerebral ischemia.
  
  
  OBJECTIVE
  We sought to define the (1) incidence; (2) timing; and (3) magnitude of intraoperative cerebral desaturation events (CDEs) in subjects undergoing arthroscopic shoulder surgery in the beach chair position, as well as whether (4) the length of surgery was an independent risk factor for intraoperative CDEs.
  
  
  METHODS
  Regional cerebral tissue oxygen saturation (rSO2) was monitored intraoperatively using near-infrared spectroscopy on 51 consecutive patients undergoing arthroscopic shoulder surgery in the beach chair position. Intraoperative decreases in rSO2 of 20% or greater were defined as CDEs.
  
  
  RESULTS
  The incidence of intraoperative CDEs in our series was 18% (nine of 51). Among the patients demonstrating CDE (n = 9), the mean time to onset of initial CDE was 18 minutes 38 seconds postinduction. Of those experiencing CDEs, the mean maximal decrease in rSO2 was 32% from preoperative baseline per patient. Additionally, the mean number of separate CDE instances was 1.89 in this patient population with an average duration of 3 minutes 3 seconds per instance. There was no statistically significant difference (p = 0.202) between patients demonstrating CDEs and those without in regard to length of surgery (95 versus 88 minutes).
  
  
  CONCLUSIONS
  The degree and duration of cerebral ischemia required to produce neurocognitive dysfunction in this patient population remains undefined; however, cerebral oximetry with near-infrared spectroscopy allows prompt identification and treatment of decreased cerebral perfusion. We believe protocols aimed at detecting and reversing CDE may improve patient safety.
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Loyola University Health System, 2160 South First Avenue, Maywood, IL, 60153, USA, dsalazar@post.com.
authors.forename: Dane
authors.initials: D
authors.lastname: Salazar
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Sears
authors.forename: John
authors.initials: J
authors.lastname: Andre
authors.forename: Pietro
authors.initials: P
authors.lastname: Tonino
authors.forename: Guido
authors.initials: G
authors.lastname: Marra
mesh_terms: D000328:Adult; D000368:Aged; D001182:Arthroscopy / Q000009:adverse effects* / Q000379:methods; D002545:Brain Ischemia / Q000209:etiology*; D003072:Cognition Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D056888:Patient Positioning; D011187:Posture; D011446:Prospective Studies; D012785:Shoulder Joint / Q000601:surgery*