Effect of phenylephrine on hemodynamics and splenic dimensions in horses

Joanne Hardy From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

Search for other papers by Joanne Hardy in
Current site
Google Scholar
PubMed
Close
 DVM, MS
,
Richard M. Bednarski From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

Search for other papers by Richard M. Bednarski in
Current site
Google Scholar
PubMed
Close
 DVM, MS
, and
David S. Biller From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210.

Search for other papers by David S. Biller in
Current site
Google Scholar
PubMed
Close
 DVM

Click on author name to view affiliation information

Summary

Pharmacologically induced splenic contraction might be useful during certain medical or surgical procedures in horses. The effects of phenylephrine, an α1-adrenergic receptor agonist, on hemodynamic function and splenic dimensions were examined in 6 healthy adult horses. Phenylephrine infusion (1, 3, or 6 μg/kg of body weight/min for 15 minutes) resulted in a dose-related increase in mean pulmonary artery pressure; right atrial pressure; systolic, mean, and diastolic arterial pressures; and packed cell volume (P = 0.0001). Concurrent decreases in heart rate and specific cardiac output (P = 0.0001) were detected, but stroke volume did not vary significantly. The rate pressure product was increased only at the highest phenylephrine dosage (P = 0.012). Bradycardia was observed at all dosages during drug infusion, and second - degree atrioventricular block was detected in 88 % of horses during infusion. Phenylephrine administration caused dose - dependent splenic contraction, as detected by ultrasonographic measurements of splenic area and thickness (P = 0.0001).At the 3- and 6-μg/kg/min infusion rates, splenic area was reduced to 28 and 17 % of baseline measurement, respectively. Splenic dimensions had returned to baseline values by 35 minutes after the end of infusion. Infusion of phenylephrine at a dosage of 3 μg/kg/min for 15 minutes can be used to induce splenic contraction in horses.

Summary

Pharmacologically induced splenic contraction might be useful during certain medical or surgical procedures in horses. The effects of phenylephrine, an α1-adrenergic receptor agonist, on hemodynamic function and splenic dimensions were examined in 6 healthy adult horses. Phenylephrine infusion (1, 3, or 6 μg/kg of body weight/min for 15 minutes) resulted in a dose-related increase in mean pulmonary artery pressure; right atrial pressure; systolic, mean, and diastolic arterial pressures; and packed cell volume (P = 0.0001). Concurrent decreases in heart rate and specific cardiac output (P = 0.0001) were detected, but stroke volume did not vary significantly. The rate pressure product was increased only at the highest phenylephrine dosage (P = 0.012). Bradycardia was observed at all dosages during drug infusion, and second - degree atrioventricular block was detected in 88 % of horses during infusion. Phenylephrine administration caused dose - dependent splenic contraction, as detected by ultrasonographic measurements of splenic area and thickness (P = 0.0001).At the 3- and 6-μg/kg/min infusion rates, splenic area was reduced to 28 and 17 % of baseline measurement, respectively. Splenic dimensions had returned to baseline values by 35 minutes after the end of infusion. Infusion of phenylephrine at a dosage of 3 μg/kg/min for 15 minutes can be used to induce splenic contraction in horses.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 75 75 42
PDF Downloads 31 31 10
Advertisement