From the Guidelines
Milrinone does not cause vasoconstriction in cerebral vessels, but rather has a neutral or beneficial effect on pulmonary vascular resistance (PVR) and can cause systemic vasodilation, including potential cerebral vasodilation. The study by Zamanian et al. 1 discusses the management of critically ill pulmonary arterial hypertension (PAH) patients, including the use of inotropes and vasopressors. According to this study, inotropes such as milrinone have neutral or beneficial effects on PVR, which suggests that milrinone is unlikely to cause vasoconstriction in cerebral vessels.
Some key points to consider when using milrinone include:
- Milrinone is a phosphodiesterase-3 inhibitor that can increase intracellular calcium in cardiac muscle and vascular smooth muscle, leading to vasodilation
- The typical dosing of milrinone includes a loading dose followed by a continuous infusion, with dosage adjustments necessary for patients with renal impairment
- When administering milrinone, it's essential to monitor for hypotension due to its systemic vasodilatory effects, which could potentially reduce cerebral perfusion pressure if blood pressure drops significantly
- Inhaled nitric oxide (iNO) can also be used to decrease PVR and improve cardiac output in PAH patients, and has a short half-life and short onset of action, making it a useful agent in the ICU setting 1.
Overall, the use of milrinone in clinical practice should be guided by its potential benefits and risks, including its effects on systemic and pulmonary vascular resistance, and its potential to cause hypotension.
From the FDA Drug Label
Milrinone lactate is a positive inotrope and vasodilator, with little chronotropic activity Milrinone lactate, at relevant inotropic and vasorelaxant concentrations, is a selective inhibitor of peak III cAMP phosphodiesterase isozyme in cardiac and vascular muscle Milrinone lactate also produces dose-related and plasma concentration-related increases in forearm blood flow in patients with congestive heart failure, indicating a direct arterial vasodilator activity of the drug. Doses of milrinone lactate may produce hypotension because of its vasodilator effect.
Milrinone (Inamrinone) does not cause vasoconstriction in the cerebral vessels, it is a vasodilator. The FDA drug label indicates that milrinone lactate has a direct arterial vasodilator activity, which suggests that it would cause vasodilation, not vasoconstriction, in blood vessels, including potentially cerebral vessels [2] [3].
From the Research
Milrinone and Cerebral Vasoconstriction
- There is no evidence to suggest that Milrinone causes vasoconstriction in cerebral vessels. In fact, the studies suggest that Milrinone has vasodilating properties, which can help reverse cerebral vasospasm 4, 5, 6.
- The studies have shown that Milrinone can increase arterial diameter and improve neurological outcomes in patients with cerebral vasospasm secondary to aneurysmal subarachnoid hemorrhage 4, 5.
- However, Milrinone can have systemic effects, such as increasing heart rate and cardiac output, and decreasing mean arterial pressure 7.
- Additionally, Milrinone can be associated with cardiomyopathy and arrhythmia, particularly when used in combination with catecholamines 8.
Mechanism of Action
- Milrinone is a phosphodiesterase inhibitor that combines vasodilating and inotropic properties, making it effective in treating cerebral vasospasm 4.
- The vasodilating effect of Milrinone can help increase blood flow to the affected areas of the brain, improving neurological outcomes 4, 5.
Clinical Use
- Milrinone can be administered intra-arterially or intravenously, and the choice of protocol may depend on the individual patient's needs and the institution's guidelines 5.
- The use of Milrinone to treat cerebral vasospasm following traumatic subarachnoid hemorrhage has also been reported, with promising results 6.
- However, close monitoring of patients receiving Milrinone is necessary to detect potential cardiac complications, such as cardiomyopathy and arrhythmia 8.