A nurse is caring for a client with asthma who is prescribed metoprolol. The nurse should monitor the client for which of the following?

Choice A reason: Vasoconstriction is the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. This increases the resistance to blood flow and raises the blood pressure. Phenylephrine is used as a vasopressor to treat hypotension, which is a condition of low blood pressure that can cause dizziness, fainting, or organ damage. The nurse should monitor the blood pressure and the peripheral pulses of the patient after administering phenylephrine.

Choice B reason: Bronchodilation is not the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. It has no effect on the beta2 receptors on the bronchial smooth muscle, which are responsible for bronchodilation or widening of the airways. Phenylephrine is not used to treat respiratory conditions, such as asthma or chronic obstructive pulmonary disease, that cause bronchoconstriction or narrowing of the airways. The nurse should assess the respiratory rate and the breath sounds of the patient after administering phenylephrine.

Choice C reason: Diuresis is not the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. It has no effect on the kidney function or the urine output. Phenylephrine is not used to treat fluid retention or edema, which are conditions of excess fluid in the body that can cause swelling, weight gain, or heart failure. The nurse should measure the urine output and the specific gravity of the patient after administering phenylephrine.

Choice D reason: Decreased heart rate is not the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. It has little or no effect on the beta1 receptors on the heart, which are responsible for increasing the heart rate and the contractility. Phenylephrine may actually cause a reflex bradycardia, which is a slow heart rate that occurs when the baroreceptors in the blood vessels sense an increase in blood pressure and send signals to the brain to lower the heart rate. Phenylephrine is not used to treat tachycardia, which is a fast heart rate that can cause palpitations, chest pain, or arrhythmias. The nurse should monitor the electrocardiogram and the heart rate of the patient after administering phenylephrine.

Choice A reason: This is incorrect. SQ (subcutaneous) administration involves injecting a drug into the fatty tissue under the skin. This route is slower than IV or IM administration, as the drug has to diffuse through the tissue before reaching the bloodstream.

Choice B reason: This is incorrect. PO (by mouth) administration involves swallowing a drug and absorbing it through the digestive system. This route is the slowest of all, as the drug has to pass through the stomach and the liver before reaching the bloodstream. The drug may also be affected by the first pass effect, which reduces its bioavailability.

Choice C reason: This is correct. IV (intravenous) administration involves injecting a drug directly into a vein. This route is the fastest of all, as the drug enters the bloodstream immediately and reaches the target site quickly. The drug also has 100% bioavailability, meaning none of it is lost or degraded.

Choice D reason: This is incorrect. IM (intramuscular) administration involves injecting a drug into a muscle. This route is faster than SQ or PO administration, as the drug can be absorbed by the capillaries in the muscle. However, it is still slower than IV administration, as the drug has to cross the muscle membrane before reaching the bloodstream.