title: Cardiovascular and respiratory effects of incremental doses of dopamine and phenylephrine in the management of isoflurane-induced hypotension in cats with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  To determine cardiopulmonary effects of incremental doses of dopamine and phenylephrine during isoflurane-induced hypotension in cats with hypertrophic cardiomyopathy (HCM).
  
  
  METHODS
  6 adult cats with severe naturally occurring HCM.
  
  
  METHODS
  Each cat was anesthetized twice (once for dopamine treatment and once for phenylephrine treatment; treatment order was randomized). Hypotension was induced by increasing isoflurane concentration. Cardiopulmonary data, including measurement of plasma concentration of cardiac troponin I (cTnI), were obtained before anesthesia, 20 minutes after onset of hypotension, and 20 minutes after each incremental infusion of dopamine (2.5, 5, and 10 μg/kg/min) or phenylephrine (0.25, 0.5, and 1 μg/kg/min).
  
  
  RESULTS
  Mean ± SD end-tidal isoflurane concentration for dopamine and phenylephrine was 2.44 ± 0.05% and 2.48 ± 0.04%, respectively. Cardiac index and tissue oxygen delivery were significantly increased after administration of dopamine, compared with results after administration of phenylephrine. Systemic vascular resistance index was significantly increased after administration of phenylephrine, compared with results after administration of dopamine. Oxygen consumption remained unchanged for both treatments. Systemic and pulmonary arterial blood pressures were increased after administration of both dopamine and phenylephrine. Acid-base status and blood lactate concentration did not change and were not different between treatments. The cTnI concentration increased during anesthesia and infusion of dopamine and phenylephrine but did not differ significantly between treatments.
  
  
  CONCLUSIONS
  Dopamine and phenylephrine induced dose-dependent increases in systemic and pulmonary blood pressure, but only dopamine resulted in increased cardiac output. Hypotension and infusions of dopamine and phenylephrine caused significant increases in cTnI concentrations.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. ajwiese@ucsd.edu
authors.forename: Ashley J
authors.initials: AJ
authors.lastname: Wiese
authors.forename: Linda S
authors.initials: LS
authors.lastname: Barter
authors.forename: Jan E
authors.initials: JE
authors.lastname: Ilkiw
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kittleson
authors.forename: Bruno H
authors.initials: BH
authors.lastname: Pypendop
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002312:Cardiomyopathy, Hypertrophic / Q000662:veterinary*; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D018592:Cross-Over Studies; D004298:Dopamine / Q000494:pharmacology* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D007022:Hypotension / Q000188:drug therapy / Q000662:veterinary*; D007530:Isoflurane; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology* / Q000627:therapeutic use; D011446:Prospective Studies; D019210:Troponin I / Q000097:blood; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D019210:Troponin I; D010656:Phenylephrine; D007530:Isoflurane; D010100:Oxygen; D004298:Dopamine