Left-sided heart failure is characterized by

Choice A reason: This is not a correct statement. LABAs stand for long-acting beta2-agonists, which are a class of medications that relax the smooth muscles of the airways and improve the airflow in patients with asthma or COPD. However, LABAs do not reduce the risk of asthma-related deaths, and may even increase it if used alone without an inhaled glucocorticoid, which is a type of anti-inflammatory medication.

Choice B reason: This is not a correct statement. LABAs cannot be used on an as-needed basis to treat symptoms, as they have a slow onset of action and a long duration of effect. LABAs are meant to be used as a maintenance therapy to prevent asthma exacerbations, not to relieve acute symptoms. For quick relief of symptoms, patients should use a short-acting beta2-agonist, such as albuterol or salbutamol.

Choice C reason: This is not a correct statement. LABAs are not safer than short-acting beta2 agonists, as they have similar side effects, such as tachycardia, tremors, and hypokalemia. LABAs also have a black box warning that they may increase the risk of asthma-related deaths if used without an inhaled glucocorticoid.

Choice D reason: This is the correct statement. LABAs should be combined with an inhaled glucocorticoid, as this combination has been shown to improve the asthma control, reduce the frequency and severity of exacerbations, and decrease the inflammation and airway hyperresponsiveness. The inhaled glucocorticoid also reduces the risk of adverse effects and mortality associated with LABAs.

Choice A reason: This is not the preferred agent for the initial treatment of heart failure. Vasodilators are a class of medications that lower the blood pressure by relaxing the blood vessels and reducing the resistance to blood flow. They can be used to treat hypertension, angina, and heart failure, but they are usually added to other medications, such as diuretics or beta blockers, to improve the symptoms and outcomes.

Choice B reason: This is the preferred agent for the initial treatment of heart failure. Diuretics are a class of medications that increase the urine output and reduce the fluid retention in the body. They can be used to treat hypertension, edema, and heart failure, as they reduce the preload and afterload on the heart, and decrease the pulmonary congestion and peripheral edema.

Choice C reason: This is not the preferred agent for the initial treatment of heart failure. Calcium channel blockers are a class of medications that lower the blood pressure and heart rate by blocking the calcium channels in the heart and blood vessels, which cause vasodilation and reduced cardiac contractility. They can be used to treat hypertension, angina, and arrhythmias, but they are not recommended for most patients with heart failure, as they may worsen the cardiac function and increase the mortality.

Choice D reason: This is not the preferred agent for the initial treatment of heart failure. Direct renin inhibitors are a class of medications that lower the blood pressure by inhibiting the enzyme renin, which initiates the renin-angiotensin-aldosterone system, a hormonal pathway that regulates the blood pressure and fluid balance. They can be used to treat hypertension, but they have not been proven to be effective or safe for patients with heart failure.