title: The effect of dexmedetomidine on nutrient organ blood flow.
abstract: The alpha 2-adrenergic agonist dexmedetomidine decreases not only heart rate, myocardial contractility, and oxygen demand, but also cardiac output (Q). To investigate whether this reduction in Q could critically impair perfusion of individual organs, we studied the effect of dexmedetomidine on nutrient blood flow to the heart, brain, kidney, spleen, skin, intestine, liver, and arteriovenous anastomoses using the radioactive microsphere technique. Studies were conducted in 14 dogs with an open chest and anesthetized with either chloralose/urethane (CU) or fentanyl/halothane (FH), to create different baseline conditions. Hemodynamic variables, organ blood flow, arterial and mixed venous oxygen, and lactate content were measured before and after administration of 0.1, 1, and 10 micrograms/kg dexmedetomidine intravenously (IV). After 10 micrograms/kg dexmedetomidine Q decreased in both groups by 50%. The decrease in blood flow varied greatly between the organs. While flow through arteriovenous anastomoses and skin decreased by 70% to 90%, renal blood flow decreased by 30%, cerebral blood flow only when baseline blood flow was high (FH dogs), and left ventricular blood flow only in the CU group, where the largest decrease in hemodynamic variables occurred. Oxygen consumption decreased only in CU dogs, but so did arterial lactate levels. These data indicate that dexmedetomidine causes considerable redistribution of Q, predominantly reducing blood flow to less vital organs and shunt flow.
authors.affiliation: Department of Anesthesiology, University Hospital Maastricht, The Netherlands.
authors.forename: C J
authors.initials: CJ
authors.lastname: Lawrence
authors.forename: F W
authors.initials: FW
authors.lastname: Prinzen
authors.forename: S
authors.initials: S
authors.lastname: de Lange
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D000818:Animals; D001163:Arteriovenous Anastomosis / Q000187:drug effects; D001775:Blood Circulation / Q000187:drug effects*; D002302:Cardiac Output / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D002698:Chloralose / Q000008:administration & dosage; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D006221:Halothane / Q000008:administration & dosage; D006339:Heart Rate / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology*; D007422:Intestines / Q000098:blood supply; D007773:Lactates / Q000097:blood; D008102:Liver Circulation / Q000187:drug effects; D008297:Male; D020926:Medetomidine; D009200:Myocardial Contraction / Q000187:drug effects; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D012867:Skin / Q000098:blood supply; D013154:Spleen / Q000098:blood supply; D014520:Urethane / Q000008:administration & dosage; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D007093:Imidazoles; D007773:Lactates; D002698:Chloralose; D014520:Urethane; D020926:Medetomidine; D010100:Oxygen; D005283:Fentanyl; D006221:Halothane