A client with Parkinson's disease is prescribed carbidopa-levadopa [Sinemet]. Which of the following side effects does the nurse recognize can occur with this medication?

A) Respiratory acidosis:
This condition is characterized by an increase in PaCO2 and a decrease in pH, which is exactly what is seen in these ABG results. The pH of 7.21 indicates acidosis (normal pH range is 7.35–7.45), and the PaCO2 of 50 is elevated (normal PaCO2 range is 35–45 mmHg), indicating that carbon dioxide retention is contributing to the acidosis. In respiratory acidosis, the lungs are unable to adequately expel CO2, leading to an accumulation of CO2 in the blood, which decreases the pH. The HCO3 (bicarbonate) is within normal range (22–28 mEq/L), suggesting that there has not yet been compensation by the kidneys, which would typically increase bicarbonate levels to buffer the acidosis.

B) Metabolic alkalosis:
Metabolic alkalosis is characterized by an elevated pH (above 7.45) and an elevated HCO3 (above 28 mEq/L). In this case, the pH is low (7.21), and the bicarbonate level (HCO3) is normal (26), so metabolic alkalosis is not the correct diagnosis.

C) Respiratory alkalosis:
Respiratory alkalosis occurs when there is decreased PaCO2 (below 35 mmHg) and an elevated pH (above 7.45), typically due to hyperventilation. Since the PaCO2 is elevated (50 mmHg) in this case, it rules out respiratory alkalosis.

D) Metabolic acidosis:
Metabolic acidosis is characterized by a low pH (below 7.35) and a low HCO3 (below 22 mEq/L). While the pH is low in this case, the HCO3 is normal (26 mEq/L), which suggests that the acidosis is not metabolic in origin. Metabolic acidosis would typically show a low bicarbonate level, indicating that the kidneys are not able to compensate effectively.

A) Prednisone:
Prednisone is a corticosteroid commonly used to reduce inflammation in conditions such as asthma. It is appropriate in this case for managing the asthma exacerbation, as steroids help to decrease airway inflammation and improve breathing. There is no immediate concern about prednisone in this client with both asthma and a history of heart failure.

B) Metoprolol:
Metoprolol is a beta-blocker, typically used for managing heart failure, hypertension, and arrhythmias. However, beta-blockers are generally avoided in asthma patients because they can exacerbate bronchospasm. In patients with asthma, beta-blockers can block beta-2 receptors in the lungs, leading to constriction of the airways and worsening respiratory symptoms.

C) Labetolol:
Labetolol is a beta-blocker with both alpha- and beta-blocking effects, which can help lower blood pressure and manage heart failure. While labetalol can also block beta-2 receptors, it has a relatively lower risk of causing bronchospasm compared to non-selective beta-blockers like metoprolol. However, it still poses some risk to patients with asthma. Given the patient's history of asthma, labetolol may still require caution, but it is generally considered safer than other beta-blockers.

D) Albuterol:
Albuterol is a bronchodilator used to relieve acute asthma symptoms and is commonly prescribed for asthma exacerbations. It works by stimulating beta-2 receptors in the lungs, leading to the relaxation of bronchial smooth muscles and improved airflow. In this case, albuterol is an appropriate medication for managing asthma exacerbation and should be used to relieve symptoms of shortness of breath and wheezing.