A nurse is caring for a client who has quadriplegia from a spinal cord injury and reports having a severe headache. The nurse obtains a blood pressure reading of 210/108 mm Hg and suspects the client is experiencing autonomic dysreflexia. Which of the following actions should the nurse take first?

A. Administer a nitrate antihypertensive: Administering antihypertensives may be necessary if blood pressure remains dangerously high, but pharmacologic intervention is not the first action. Immediate noninvasive measures to reduce the stimulus causing autonomic dysreflexia take priority to prevent further elevation. B. Assess the client for bladder distention: Bladder distention is a common trigger for autonomic dysreflexia. Identifying and relieving the cause is essential, but assessment requires the client to be safely positioned first to prevent complications from sudden blood pressure elevation. C. Obtain the client's heart rate: Monitoring heart rate is important for detecting bradycardia associated with autonomic dysreflexia, but it is not the first intervention. Immediate action to lower blood pressure and reduce the risk of stroke or seizure takes precedence. D. Place the client in a high-Fowler's position: Elevating the head of the bed to a high-Fowler’s position is the first priority because it uses gravity to help lower blood pressure and reduce cerebral perfusion pressure. This immediate action helps prevent life-threatening complications such as stroke, seizure, or myocardial ischemia while the underlying cause is identified and addressed.