A nurse is caring for a client with Parkinson's disease. The client has been prescribed oral diphenhydramine. Which of the following therapeutic outcomes should the nurse expect to see following administration of this medication?

A. "Monitor your blood pressure since hypertension can occur.": Baclofen primarily acts as a central nervous system muscle relaxant by stimulating GABA-B receptors. While it can cause hypotension in some cases, hypertension is not a common adverse effect. Blood pressure monitoring for high readings is generally not required unless indicated by comorbid conditions.

B. "Do not take antihistamines with this medication.": Baclofen can cause central nervous system depression, including drowsiness, dizziness, and impaired coordination. Concomitant use of other CNS depressants, such as antihistamines, can increase the risk of excessive sedation and respiratory depression. Clients should avoid combining these medications.

C. "Stop taking this medication immediately if you are drowsy.": Sudden discontinuation of baclofen, especially after prolonged use, can precipitate severe withdrawal symptoms, including hallucinations, seizures, and increased spasticity. Drowsiness is a common, expected side effect and should be monitored, but the medication should not be stopped abruptly.

D. "Expect muscle spasticity to worsen initially.": Baclofen is prescribed to reduce muscle spasticity in multiple sclerosis. While some transient effects such as mild weakness may occur initially, spasticity should gradually decrease rather than worsen. Worsening spasticity is not a typical expectation when starting therapy.

A. Slow, irregular respirations: Increasing intracranial pressure can compress or damage the brainstem, which controls basic respiratory function. As the pressure rises, the normal rhythmic drive of the medulla and pons becomes impaired, resulting in slow, irregular, or even intermittent breathing patterns. This is a hallmark sign of brainstem involvement and worsening neurological status.

B. Rapid, shallow respirations: Rapid, shallow breathing is more commonly associated with metabolic acidosis, hypoxia, or pain rather than direct brainstem compromise. While it reflects respiratory distress, it does not specifically indicate increased intracranial pressure.

C. Nasal flaring: Nasal flaring is a sign of increased work of breathing and is typically seen in pediatric patients with respiratory distress. It does not reflect brainstem dysfunction or elevated intracranial pressure.

D. Asymmetric chest excursion: Unequal chest expansion indicates localized lung or musculoskeletal issues, such as pneumothorax, atelectasis, or muscle weakness. It is not a direct indicator of increased intracranial pressure or brainstem involvement.