A nurse caring for a client taking dantrolene for malignant hyperthermia after a recent surgery should evaluate which assessment item to determine therapeutic effect?

• A. Relief of muscle rigidity
• B. Improved appetite
• C. Decreased heart rate
• D. Enhanced mental status

Answer: (A)

The central idea is that the effectiveness of dantrolene for malignant hyperthermia is reflected by relief of skeletal muscle rigidity. Dantrolene works by inhibiting calcium release from the sarcoplasmic reticulum in skeletal muscle, which reduces excitation-contraction coupling and muscle contractions. In malignant hyperthermia, uncontrolled calcium release causes sustained muscle contraction, excessive heat production, and metabolic problems. When muscle rigidity improves, it indicates calcium-driven contraction is subsiding and the hypermetabolic crisis is abating. Therefore, monitoring for decreased rigidity and improved mobility best shows the therapeutic effect. Appetite, heart rate, and mental status aren’t direct measures of how well dantrolene is controlling the muscle calcium dynamics, though they may improve as the patient stabilizes.