Dopamine stabilizes milrinone-induced changes in heart rate and arterial pressure during anaesthesia with isoflurane:

Impella RP Versus Pharmacologic Vasoactive Treatment in Profound Cardiogenic Shock due to Right Ventricular Failure

The aim was to translationally compare a pharmacologic strategy versus treatment with the Impella RP in profound RV cardiogenic shock (CS). The pigs were allocated to either vasoactive therapy with norepinephrine (0.10 μg/kg/min) for the first 30 min, supplemented by an infusion of milrinone (0.4 μg/kg/min) for additional 150 min, or treatment with the Impella RP device for 180 min. Total RV workload (Pressure-volume-area × heart rate*10³(mmHg/min)) remained unaffected upon treatment with the Impella RP and increased in the vasoactive group (CS 179[147;228] to norepinephrine 268[247;306](p = 0.002 compared to Impella RP) and norepinephrine + milrinone 366[329;422] (p = 0.002 compared to Impella RP). A trend towards higher venous cerebral oxygen saturation was observed with norepinephrine than Impella RP (Impella RP 51[47;61]% vs norepinephrine 62[57;71]%; p = 0.07), which became significantly higher with the addition of milrinone (Impella RP 45[32;63]% vs norepinephrine + milrinone 73[66;81]%; p = 0.002). The Impella RP unloaded the failing RV. In contrast, vasoactive treatment led to enhanced cerebral venous oxygen saturation.

Vasopressor and Inotrope Therapy in Cardiac Critical Care

Patients admitted to the cardiac intensive care unit (CICU) are often in shock and require hemodynamic support. Identifying and addressing the pathophysiology mechanisms operating in an individual patient is crucial to achieving a successful outcome, while initiating circulatory support therapy to restore adequate tissue perfusion. Vasopressors and inotropes are the cornerstone of supportive medical therapy for shock, in addition to fluid resuscitation when indicated. Timely initiation of optimal vasopressor and inotrope therapy is essential for patients with shock, with the ultimate goals of restoring effective tissue perfusion in order to normalize cellular metabolism. Use of vasoactive agents for hemodynamic support of patients with shock should take both arterial pressure and tissue perfusion into account when choosing therapeutic interventions. For most patients with shock, including cardiogenic or septic shock, norepinephrine (NE) is an appropriate choice as a first-line vasopressor titrated to achieve an adequate arterial pressure due to a lower risk of adverse events than other catecholamine vasopressors. If tissue and organ perfusion remain inadequate, an inotrope such as dobutamine may be added to increase cardiac output to a sufficient level that meets tissue demand. Low doses of epinephrine or dopamine may be used for inotropic support, but high doses of these drugs carry an excessive risk of adverse events when used for vasopressor support and should be avoided. When NE alone is inadequate to achieve an adequate arterial pressure, addition of a noncatecholamine vasopressor such as vasopressin or angiotensin-II is reasonable, in addition to rescue therapies that may improve vasopressor responsiveness. In this review, we discuss the pharmacology and evidence-based use of vasopressor and inotrope drugs in critically ill patients, with a focus on the CICU population.

Diazepam Enhances Inotropic Responses to Dopamine in Rat Ventricular Myocardium

Diazepam inhibits phosphodiesterase type 4 and enhances the effect of some 3',5'-cyclic adenosine monophosphate (cAMP)-dependent positive inotropic drugs. We sought to determine whether diazepam and the selective phosphodiesterase type 4 inhibitor rolipram enhances the contractile response and cAMP levels induced by dopamine in rat myocardium. Dopamine (3-100 microM) produced concentration-dependent positive inotropic effects (-log EC50 = 5.21 +/- 0.2, n = 5), which were augmented in the presence of 10 microM diazepam (-log EC50 = 5.40 +/- 0.08, n = 6, P < 0.05) or 1 microM rolipram (-log EC50 = 5.41 +/- 0.1, n = 6, P < 0.05). The effect of diazepam was not mimicked by 100 microM gamma-aminobutyric acid nor it was antagonized by a 5 microM concentration of the blockers of central and peripheral type benzodiazepine receptors, flumazenil and PK 11195. cAMP levels (pmol/g) produced by dopamine (744.4 +/- 111.8, n = 5) in this tissue were enhanced by the presence of diazepam (1073 +/- 97.7, n = 6, P < 0.05) or rolipram (1034.0 +/- 245.2, n = 5, P < 0.05). Therefore, diazepam, like rolipram, augments the inotropic and biochemical effects of dopamine in rat myocardium. This effect is not mediated by benzodiazepine receptors but is probably the consequence of the phosphodiesterase type 4 inhibitory activity of diazepam.