|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 Ã¬g 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 Ã¬g kg1 minute1, while 10 Ã¬g 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 Ã¬g 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), 301Â311.
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