Hyperpyrexia during anaesthesia

Malignant hyperthermia in the early days of pediatric anesthesia: an interview with anesthesiology pioneer, Dr. John F. Ryan

Dr. John F. Ryan (1935 - ), Associate Professor of Anaesthesia at the Harvard Medical School, influenced the careers of hundreds of residents and fellows-in-training while instilling in them his core values of resilience, hard work, and integrity. His authoritative textbook, A Practice of Anesthesia for Infants and Children, remains as influential today as it did when first published decades ago. Although he had had many accomplishments, he identified his experiences caring for patients with malignant hyperthermia and characterizing the early discovery of this condition as his defining contribution to medicine. Based on a series of interviews with Dr. Ryan, this article reviews a remarkable career that coincides with the dawn of modern pediatric anesthetic practice.

Malignant hyperthermia

Malignant hyperthermia is a hereditary trait characterized by hypercatabolic reactions induced by anesthetic drugs, or physical or emotional stress. Patients must be treated quickly and efficiently in order to prevent irreversible organ damage and death.

Malignant hyperthermia

A case has been presented that illustrates successful managment of a patient with suspected malignant hyperthermia. The causes of this disorder are uncertain. If screening procedures identify a patient as susceptible to this disorder, careful planning in the preoperative stage is indicated. Preparedness during the operative procedure for any emergency is mandatory. Early and effective treatment seems to be the only method of preventing mortality with patients experiencing malignant hyperthermia.

Malignant hyperpyrexia. Further muscle studies in asymptomatic carriers identified by creatinine phosphokinase screening

The history, clinical presentation, and management of malignant hyperpyrexia are presented. The aetiology seems to be associated with some inherited abnormality which affects the movement and binding of calcium ions in the sarcoplasmic reticulum, sarcoplasm, and mitochondria. Whether this is a primary muscular defect or secondary to some trophic neural influence is yet to be established. The subjects carrying the abnormal trait show evidence of a myopathy which is subclinical in most instances and revealed only by estimation of serum CPK or biopsy. In some families where the myopathy is clinically obvious there may be, in addition, a variety of musculoskeletal abnormalities. A plea is made for routine monitoring of temperature during anaesthesia and for procainamide or procaine to be readily available in all operating theatres. A history of anaesthetic deaths in a family calls for special care, and, if the serum CPK is elevated, suxamethonium and halothane are to be avoided. Families with orthopaedic and muscular abnormalities are at increased risk and should have estimation of serum CPK before surgery. As a bonus of this study it is suggested that serum CPK estimations be used to screen pigs for selective breeding and so eliminate the disease, which causes soft exudative pork.

Effects of monoamine oxidase inhibitors on the hypothermia produced in cats by halothane

1. In cats, the effects of intraperitoneal injections of four monoamine oxidase (MAO) inhibitors, tranylcypromine, pheniprazine, pargyline, and nialamide, were examined on rectal temperature and on the hypothermia during anaesthesia produced by a 2 hr period of halothane inhalation.2. A 2 hr period of halothane inhalation produced a steady fall in temperature amounting to between 2 degrees and 3.5 degrees C. After discontinuation of halothane inhalation, temperature quickly returned to the pre-anaesthetic level but no pyrexia developed. A peculiar stiffness of the leg muscles occurred in several experiments either at the beginning of the inhalation or after its discontinuation.3. An injection of tranylcypromine (5 mg/kg) caused a rise in rectal temperature and prevented the hypothermia of halothane anaesthesia. This effect lasted for at least 4 hr; 20 hr after the injection, halothane again caused hypothermia.4. An injection of pheniprazine (10 mg/kg) usually caused a small rise in temperature which was not sustained. Pheniprazine not only prevented the hypothermia of halothane anaesthesia during the subsequent 20 hr, but during the first few hours after the injection halothane inhalation actually produced a steep rise in temperature.5. An injection of pargyline (50 mg/kg) had no effect on temperature but the hypothermia due to halothane inhalation was prevented 1 hr after the injection and attenuated after 20 hr. Injection of 200 mg/kg caused a steady rise in temperature which was accelerated when halothane was administered 1 hr later.6. An injection of nialamide (10, 25 or 50 mg/kg) had no immediate effect on temperature, but pyrexia developed overnight after the two larger doses. The effect on the hypothermia due to halothane inhalation was greater 20 hr after the injection than it was after 1 to 2 hr. Twenty hours after injection of the two larger doses, halothane no longer produced hypothermia but caused a lethal rise in temperature either during or after its inhalation.7. In rabbits, the effect on temperature of halothane inhalation varied. Either temperature rose slightly or it fell, but not as much as in cats. In one rabbit in which the inhalation had produced a transient rise, pyrexia developed 40 min after discontinuation of halothane.

Hyperpyrexia during anaesthesia

Work in pigs has shown that malignant hyperpyrexia during anaesthesia may occur without suxamethonium having been given. A virtually constant feature in reported cases and in our own observations is that all subjects developing hyperpyrexia had received nitrous oxide and halothane.