title: Risk factors for respiratory depression in patients undergoing retrobulbar block for vitreoretinal surgery.
abstract: OBJECTIVE
  To determine the risk factors for respiratory depression during retrobulbar block administration before vitreoretinal surgery.
  
  
  METHODS
  Prospective, observational case series of 113 patients undergoing monitored anesthesia care and retrobulbar block before vitreoretinal surgery at a tertiary medical center.
  
  
  RESULTS
  Chin lift, jaw thrust, and bag mask ventilation were performed in eight (7.1%), nine (8%), and six (5.3%) patients, respectively. No patients required intubation. Age, sex, body mass index, history of obstructive sleep apnea, American Society of Anesthesiologists physical status level, and baseline oxygen saturation were not predictive of airway intervention. Of the four anesthetic agents utilized (midazolam, fentanyl, alfentanil, and propofol), only propofol and fentanyl were associated with an increased risk for clinically significant apnea. Use of three medications for sedation was associated with a 5.4-fold increase in the relative risk of requiring a respiratory rescue intervention.
  
  
  CONCLUSIONS
  During preoperative sedation for retrobulbar block administration, the use of propofol, fentanyl, or a combination of three anesthetics is associated with a statistically significant increase in the risk for respiratory depression requiring resuscitation.
authors.forename: Ruwan A
authors.initials: RA
authors.lastname: Silva
authors.forename: Jody C
authors.initials: JC
authors.lastname: Leng
authors.forename: Lisa
authors.initials: L
authors.lastname: He
authors.forename: John G
authors.initials: JG
authors.lastname: Brock-Utne
authors.forename: David R
authors.initials: DR
authors.lastname: Drover
authors.forename: Theodore
authors.initials: T
authors.lastname: Leng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015760:Alfentanil / Q000008:administration & dosage; D000765:Anesthesia, Conduction; D019162:Anesthetics, Combined / Q000009:adverse effects*; D018686:Anesthetics, Intravenous / Q000009:adverse effects*; D016292:Procedural Sedation; D005260:Female; D005283:Fentanyl / Q000009:adverse effects; D006801:Humans; D008297:Male; D008874:Midazolam / Q000008:administration & dosage; D008875:Middle Aged; D009407:Nerve Block; D009915:Orbit; D015742:Propofol / Q000009:adverse effects; D011446:Prospective Studies; D012131:Respiratory Insufficiency / Q000139:chemically induced* / Q000175:diagnosis; D012307:Risk Factors; D057586:Vitreoretinal Surgery; D055815:Young Adult
chemical_list: D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D015760:Alfentanil; D008874:Midazolam; D005283:Fentanyl; D015742:Propofol