title: Dexmedetomidine attenuates tourniquet-induced hyperdynamic response in patients undergoing lower limb surgeries: a randomized controlled study.
abstract: BACKGROUND
  Activation of sympathetic nervous system has a crucial role in mediating the pneumatic tourniquet inflation induced hyperdynamic response. Dexmedetomidine, a selective α(2)-adrenergic receptor agonist, has potent sympatholytic effects. We conducted this prospective, randomized, placebo-controlled, double-blinded study to elucidate the effects of dexmedetomidine on attenuating the tourniquet-induced hyperdynamic response during general anesthesia.
  
  
  METHODS
  We included a total of 72 healthy adult patients undergoing elective lower limb surgery. Under general anesthesia, patients were randomized to the dexmedetomidine or the control group (n = 36 in each group). The dexmedetomidine group received a loading dose of dexmedetomidine (0.8 μg·kg(-1) over 10 min) followed by continuous infusion of dexmedetomidine (0.4 μg·kg(-1).h(-1)) until tourniquet deflation. The control group received normal saline instead. We compared tourniquet-induced changes in hemodynamic parameters between groups to elucidate the effects of dexmedetomidine.
  
  
  RESULTS
  Tourniquet inflation induced significant increases in hemodynamic parameters, including heart rate, systolic arterial pressure, mean arterial pressure, diastolic arterial pressure, rate pressure product, cardiac output, and stroke volume in the control group. The effects of tourniquet inflation on increasing hemodynamic parameters were significantly attenuated by dexmedetomidine: heart rate (P < 0.001), systolic arterial pressure (P = 0.002), mean arterial pressure (P = 0.042), diastolic arterial pressure (P = 0.012), rate pressure product (P < 0.001), and cardiac output (P = 0.001) of the dexmedetomidine group were significantly lower than those of the control group. However, the stroke volume of these groups was comparable.
  
  
  CONCLUSIONS
  Dexmedetomidine attenuates tourniquet-induced hyperdynamic response in general anesthesia patients undergoing lower limb surgeries.
authors.affiliation: Department of Anesthesiology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Hsuan-Chih
authors.initials: HC
authors.lastname: Lao
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Tsai
authors.forename: Jung-Yuan
authors.initials: JY
authors.lastname: Su
authors.forename: Tiew-Guan
authors.initials: TG
authors.lastname: Kwok
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Huang
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology*; D000328:Adult; D000768:Anesthesia, General; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D020927:Dexmedetomidine / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D035002:Lower Extremity / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009985:Orthopedics; D011446:Prospective Studies; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D014111:Tourniquets / Q000009:adverse effects*
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D020927:Dexmedetomidine