Final answer:
The administration of dantrolene (Dantrium) postoperatively likely indicates the patient experienced Malignant hyperthermia, a severe reaction to anesthesia characterized by high body temperature and muscle contractions.
Step-by-step explanation:
The patient's chart noting the administration of dantrolene (Dantrium) immediately postoperatively suggests that the nurse suspects that the patient experienced Malignant hyperthermia. This is a severe reaction to certain drugs used for anesthesia and is characterized by a rapid increase in body temperature and severe muscle contractions.
Dantrolene is used to treat this condition by reducing muscle rigidity and metabolic rate, thus lowering body temperature. It is not commonly used for conditions such as delirium tremens, tonic-clonic seizures, or respiratory arrest, which are treated with different medications.