What is the most appropriate initial agent to administer for a patient with high-output heart failure and hypotension?

In a patient presenting with high-output heart failure and hypotension, norepinephrine is the most appropriate initial agent due to its potent vasoconstrictive properties and ability to increase systemic vascular resistance. High-output heart failure often involves elevated cardiac output but insufficient systemic perfusion, leading to hypotension. Administering norepinephrine can help stabilize blood pressure by constricting blood vessels, thereby increasing or maintaining perfusion pressure to vital organs.

While agents like dobutamine can enhance cardiac contractility and improve heart function, their vasodilatory effects may not adequately address the hypotension in this scenario. Nitroglycerin, primarily a vasodilator, could further exacerbate hypotension, especially in a patient already presenting with low blood pressure. Furosemide, a diuretic, is primarily used for fluid overload and would not directly address the hypotension or provide the necessary support for systemic vascular resistance.

Thus, the selection of norepinephrine reflects a focus on promoting hemodynamic stability in the context of high-output heart failure with hypotensive presentation.