title: Vasopressin ameliorates hypotension induced by beach chair positioning in a dose-dependent manner in patients undergoing arthroscopic shoulder surgery under general anesthesia.
abstract: BACKGROUND
  The beach chair position (BCP) is associated with hypotension that may lead to cerebral ischemia. Arginine vasopressin (AVP), a potent vasoconstrictor, has been shown to prevent hypotension in BCP. It also improves cerebral oxygenation in different animal models. The present study examined the effect of escalating doses of AVP on systemic hemodynamics and cerebral oxygenation during surgery in BCP under general anesthesia.
  
  
  METHODS
  Sixty patients undergoing arthroscopic shoulder surgery in BCP under general anesthesia were randomly allocated to receive either saline (control, n = 15) or three different doses of AVP (0.025, 0.05, or 0.075 U/kg; n = 15 each) 2 minutes before BCP. Mean arterial pressure (MAP), heart rate (HR), regional cerebral oxygen saturation (SctO2), and jugular venous oxygen saturation (SjvO2) were measured after induction of anesthesia and before (presitting in supine position) and after BCP.
  
  
  RESULTS
  AVP per se given before BCP increased MAP, and decreased SjvO2, SctO2, and HR in all patients (P < 0.05 for all). BCP decreased MAP, the magnitude of which and hence the incidence of hypotension was decreased by AVP in a dose-dependent manner. While in BCP, every dose of AVP reduced the HR and SctO2. Accordingly, it increased the incidence of cerebral desaturation (> 20% SctO2 decrease from the baseline value) with no differences in SjvO2 and the incidence of SjvO2 < 50% or SjvO2 < 40% among the groups.
  
  
  CONCLUSIONS
  AVP ameliorates hypotension associated with BCP in a dose-dependent manner in patients undergoing shoulder surgery under general anesthesia. However, AVP may have negative effects on SctO2 before and after BCP and on SjvO2 before BCP.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Cho
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Joungmin
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Sun Hong
authors.initials: SH
authors.lastname: Park
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Seongtae
authors.initials: S
authors.lastname: Jeong
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Sung-Su
authors.initials: SS
authors.lastname: Chung
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Kyung Yeon
authors.initials: KY
authors.lastname: Yoo
keywords: Arginine vasopressin; Beach chair position; Jugular venous oxygen saturation; Regional cerebral oxygen saturation