Cardiovascular and respiratory effects of incremental doses of dopamine and phenylephrine in the management of isoflurane-induced hypotension in cats with hypertrophic cardiomyopathy

Abstract

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.

Catecholamines

“…Dopamine has been reported to increase renal blood flow at dosages of less than 5 mcg/kg/min (and to decrease it to baseline at 10 mcg/kg/min) and may increase urine output, 1-3 but dopamine therapy does not appear to provide any low-dose renal-protective efficacy in people. 4,5 When administered to critically ill people, 6 septic dogs 7 (in the author's experience), anesthetized dogs, [8][9][10] and anesthetized cats, 11 dopamine generally causes a modest vasoconstriction and increase in blood pressure with little change or modest increases in cardiac output. In one study of anesthetized cats, 12 dopamine was associated with vasodilation and increases in heart rate, cardiac output, and blood pressure.…”

“…Cardiac output may decrease 13,27,28 or increase. 11,12,29 The earlier discussion regarding the different consequences of venoconstriction for norepinephrine apply also to phenylephrine.…”

Effects of dopamine, norepinephrine or phenylephrine on the prevention of hypotension in isoflurane-anesthetized cats administered vatinoxan or vatinoxan and dexmedetomidine

“…The treatment of hypotension in anesthetized cats consists of adjusting anesthetic depth, optimizing preload with fluid therapy, and administration of vasopressors or positive inotropes such as phenylephrine (a selective α1-adrenergic agonist), norepinephrine (a mixed α1, α2 and β1adrenergic agonist) and dopamine (a mixed dopamine, β1 and α1-adrenergic agonist) (Westfall et al 2017). The use of positive inotropes is generally preferred to that of vasopressors as the former increase oxygen delivery (Pascoe et al 2006b;Wiese et al 2012). However, because vatinoxan-induced hypotension in anesthetized cats appears related to excessive vasodilation, vasoconstrictors may be more effective at restoring normal blood pressure.…”