title: The effects of ephedrine on intramuscular blood flow and other cardiopulmonary parameters in halothane-anesthetized ponies.
abstract: OBJECTIVE
  To evaluate the effect of ephedrine on intramuscular blood flow and hemodynamic parameters during equine anesthesia.
  
  
  METHODS
  Prospective experimental study.
  
  
  METHODS
  Six healthy adult Welsh Mountain ponies (five males, one female, mean weight: 267 kg, range: 213-347 kg).
  
  
  METHODS
  Halothane-anesthetized ponies received an IV bolus of ephedrine (0.1 mg kg-1), followed 30 minutes later by a second IV ephedrine injection (0.2 mg kg-1). Changes in intramuscular blood flows (IMBF) in upper and lower triceps brachii were measured by laser Doppler flowmetry. Cardiopulmonary measurements were made at intervals for 30 minutes following each injection. Results were compared with values from a control group, similarly anesthetized but given saline in an earlier study.
  
  
  RESULTS
  Ephedrine at either dose increased heart rate, arterial blood pressure (AP), cardiac index (CI) and intramuscular blood flow (IMBF), the effects on these parameters being significant and long-lasting following the higher dose. Systemic vascular resistance remained unchanged, and was significantly lower than in the control saline group. PaO2decreased significantly immediately following the first injection of ephedrine, then remained unchanged for the remainder of the experiment. PaCO2increased slowly throughout the anesthetic period. One pony developed supraventricular premature complexes following the second injection. No other side effects were seen.
  
  
  CONCLUSIONS
  Ephedrine at dose rates of 0.2 mg kg-1IV consistently increased in CI, AP, and IMBF in both forelimbs.
  
  
  CONCLUSIONS
  Ephedrine may be of use to improve AP, CI and IMBF during halothane anesthesia, although the occurrence of an arrhythmia in one pony is of concern.
authors.affiliation: Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK. Electronic address: lyonlee@vt.edu.
authors.forename: Yong-Hoon L
authors.initials: YL
authors.lastname: Lee
authors.affiliation: Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
authors.forename: K W
authors.initials: KW
authors.lastname: Clarke
authors.affiliation: Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
authors.forename: Hatim Ik
authors.initials: HI
authors.lastname: Alibhai
authors.affiliation: Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
authors.forename: Dae Y
authors.initials: DY
authors.lastname: Song
keywords: ephedrine; halothane; horse; intramuscular blood flow; laser Doppler flowmetry