Case Study

Case Study on Skeletal Muscle Physiology

A case report of Malignant Hyperthermia in a dental clinic operating room. Anesthesia Progress 2005 Spring; 52(1): 24-28

A healthy 5-year old boy presented for arch bar placement under general anesthesia in an operating room in a

dental school. The patient had previously undergone general anesthesia without complications, and no family

history of anesthetic problems was reported.

Halothane mask induction, intravenous catheter placement, and nasal intubation proceeded uneventfully

without the aid of a muscle relaxant. Slow mask induction with increasing increments of halothane in nitrous

oxide and oxygen proceeded without incidents, and followed to appropriate general anesthesia. No

neuromuscular blocking agent was given. The patient was intubated and ventilated without difficulty.

About 25 minutes after the induction the following changes from baseline were noted: expired PCO2 raised to

60 mmHg, the spontaneous respiratory rate was above 40 bpm, heart rate had risen to 120/min. The lower

extremities were extremely rigid, and the patient’s knees and ankles would not bend upon manipulation, and

warm to touch. No masseter rigidity was detected. The Manual hyperventilation was continued, and when the

patient was allowed to spontaneously ventilate the expired PCO2 quickly rose to over 80 mmHg and the O2

saturation decreased to 95%. At this point the skin temperature was only 35 °C.

A presumptive diagnosis of malignant hyperthermia was made and the emergency cart containing a malignant

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hyperthermia kit was obtained. About 20 minute later the axillary temperature risen to 38°C. Within the 1

couples of minutes after the administration of dantrolene the temperature in the skin decrease to 36.5°C, the

PCO2 drop by 10 mmHg. Manual ventilation with 100 % O2 was continued without difficulty and ice packs

were placed in the axillary and groin areas for cooling. The IV fluids were changed to ice saline solution....