A patient is taking a beta1-adrenergic drug to improve the stroke volume of the heart. The nurse caring for this patient knows that this drug acts by increasing myocardial contractility.
Beta 1-adrenergic agents help raise cardiac output by raising the contractility of the heart muscle. Cardiac afterload is determined mainly by the level of peripheral resistance induced by constriction of the arterioles. Increasing afterload decreases stroke volume.
Beta 1-adrenergic agents do not impact cardiac afterload and preload. Cardiac preload is the stretch applied to the myocardium previous to contraction and is determined by venous return. Venous return is determined by systemic distension pressure and muscle-assisted pumps and is unaffected by beta 1 adrenergic agonists.
I believe it’s carbon dioxide, because you use your respiratory system to breathe in oxygen, and oxygen goes through your circulatory system. And you breathe out CO2.
