Anesthesia Technologist Practice Exam

What drug may cause an increase in intracellular calcium concentration in a malignant hyperthermia susceptible patient?

1. Dantrolene

2. Fentanyl

3. Succinylcholine

4. Midazolam

The correct answer is: Succinylcholine

In patients who are susceptible to malignant hyperthermia, succinylcholine is known to trigger an increase in intracellular calcium concentration. Malignant hyperthermia is a rare but life-threatening condition that can be precipitated by certain anesthetic agents, especially volatile anesthetics and depolarizing neuromuscular blockers such as succinylcholine. Succinylcholine causes muscle cells to depolarize and can lead to an uncontrolled release of calcium from the sarcoplasmic reticulum within muscle cells. This surge in calcium concentration causes sustained muscle contraction and can elevate metabolism, which may lead to dangerous physiological effects including hyperthermia, acidosis, and muscle rigidity. The other agents listed—dantrolene, fentanyl, and midazolam—do not have the same effects. Dantrolene is actually the treatment for malignant hyperthermia itself, as it works by inhibiting calcium release from the sarcoplasmic reticulum. Fentanyl is an opioid that does not directly affect calcium levels or trigger malignant hyperthermia. Midazolam, a benzodiazepine, primarily acts as an anxiolytic and sedative and does not influence intracellular calcium concentrations in the context of malignant hyperthermia.