title: Beta-adrenergic blockers and vasovagal episodes during shoulder surgery in the sitting position under interscalene block.
abstract: Shoulder surgery is often performed with patients in the sitting position under interscalene block anesthesia. Vasovagal episodes, characterized by a sudden decrease in heart rate and/or blood pressure, have a reported incidence of 17%-24% in this setting. We performed a retrospective study to determine whether there was an association between the use of beta-adrenergic blockers and the incidence of these episodes. Of the 150 patients identified, 20 (13.3%) had a vasovagal event. Similar proportions of patients had received a beta-adrenergic blocker in the group who had a vasovagal event compared with those who did not (20% vs 18%; P = 0.95). No other differences could be identified. We conclude that vasovagal episodes occur frequently in this setting with no identifiable risk factors. Beta-adrenergic blockers were not associated retrospectively with either an increased or decreased incidence of these episodes. The most likely mechanism involves the Bezold-Jarisch reflex.
  
  
  CONCLUSIONS
  In this retrospective study of 150 patients who underwent shoulder surgery in the sitting position under interscalene block, we found a 13% incidence of vasovagal episodes. Unlike a previous study, this was not affected by the use of beta-blockers. A randomized, prospective study is necessary to clarify this issue.
authors.affiliation: Department of Anesthesiology, Hospital for Special Surgery, New York 10021, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Kahn
authors.forename: M J
authors.initials: MJ
authors.lastname: Hargett
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D001794:Blood Pressure / Q000502:physiology; D001919:Bradycardia / Q000209:etiology; D002628:Chemoreceptor Cells / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007022:Hypotension / Q000209:etiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009334:Neck Muscles / Q000294:innervation*; D009407:Nerve Block; D009434:Neural Pathways / Q000502:physiology; D011187:Posture; D012018:Reflex / Q000502:physiology; D012189:Retrospective Studies; D012307:Risk Factors; D012782:Shoulder / Q000601:surgery*; D019462:Syncope, Vasovagal / Q000209:etiology*