The study was designed as a prospective, randomized, clinical trial. Twelve healthy client-owned dogs admitted for orthopedic surgery; six per group, were included.
Prior to surgery, 58 anesthetized dogs were monitored for hypotension [mean arterial pressure (MAP) <60 mmHg] that was not associated with bradycardia or excessive anesthetic depth. Ephedrine (0.2 mg kg1, IV) or dopamine (5 ìg kg1 minute1, IV) was randomly assigned for treatment in 12 hypotensive dogs.
Ten minutes after the first treatment (Tx1-10), ephedrine was repeated or the dopamine infusion rate was doubled.
Cardiovascular assessments taken at baseline, Tx1-10, and 10 minutes following treatment adjustment (Tx2-10) were compared for differences within and between treatments (p < 0.05).
Results: Ephedrine increased cardiac index (CI), stroke volume index (SVI), oxygen delivery index (DO2I), and decreased total peripheral resistance (TPR) by Tx1-10, while MAP increased transiently (<5 minutes). The second ephedrine bolus produced no further improvement.
Dopamine failed to produce significant changes at 5 ìg kg1 minute1, while 10 ìg kg1 minute1 increased MAP, CI, SVI significantly from baseline, and DO2I compared with Tx1-10. The improvement in CI, SVI, and DO2I was not significantly different between treatments at Tx2-10.
In anesthetized hypotensive dogs, ephedrine and dopamine improved cardiac output and oxygen delivery. However, the pressure-elevating effect of ephedrine is transient, while an infusion of dopamine at 10 ìg kg1 minute1 improved MAP significantly by additionally maintaining TPR.
Source: Hui C Chen, Melissa D Sinclair, Doris H Dyson (2007): Use of ephedrine and dopamine in dogs for the management of hypotension in routine clinical cases under isoflurane anesthesia*. In:
Veterinary Anaesthesia and Analgesia 34 (5), 301–311.
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