Management of a malignant hyperthermia patient during cardiopulmonary bypass

Successful management of hypothermic cardiopulmonary bypass in a malignant hyperthermia susceptible patient

Malignant hyperthermia (MH) is a potentially lethal reaction in those that are genetically predisposed, frequently triggered by inhaled anesthetics. MH is often difficult to diagnose because it is accompanied by signs and symptoms that are shared with other disorders. The diagnosis is further obscured in cardiac surgical patients, as the signs of MH can be masked by the cardiopulmonary bypass circuit (CPB) and the use of induced hypothermia. In this case-report, we describe the successful anesthetic management of a 65-year-old MH-susceptible female, confirmed via caffeine halothane contracture test, with aortic regurgitation and ascending aortic dilatation who underwent a Bentall procedure. We have also identified certain key measures for the safe anesthetic management of these patients.

Sevoflurane-induced malignant hyperthermia during cardiopulmonary bypass and moderate hypothermia

A 56-year old man was admitted for elective mitral valve repair and coronary artery bypass surgery due to mitral valve leakage and unstable angina. After induction of anaesthesia he developed a combined metabolic and respiratory acidosis. Different diagnosis were considered and we decided to treat the patient with dantrolene due to suspicion of malignant hyperthermia (MH). The patient received one dose of dantrolene 2,5 mg/kg during cardiopulmonary bypass (CPB) and a second dose of dantrolene 2,5 mg/kg during weaning from CPB. The first arterial blood gas sample taken in the intensive care unit showed relapse of the acidosis and we administered an infusion of 150 mg dantrolene over 3 hours. The patient gradually recovered without sequel and MH was verified by muscle biopsy testing.

Anaesthetic management of coronary artery bypass grafting in a patient with central core disease and susceptibility to malignant hyperthermia on statin therapy

Central core disease and malignant hyperthermia (MH) are both associated with mutations in the RYR1 gene. We report the anaesthetic management of one such patient presenting for coronary artery bypass grafting. Her medication included aspirin 75 mg, atorvastatin 20 mg, isosorbide mononitrate 60 mg, atenolol 25 mg and glyceryl trinitrite sublingual spray as required. The use of aprotinin, statins and moderate hypothermia in patients with central core disease and known susceptibility to MH has not been documented.

Review article : Malignant hyperthermia: a review for the cardiac surgical team

Malignant hyperthermia is an inherited skeletal muscle disorder. A malignant hyperthermia crisis is triggered by volatile anaesthetics and many drugs and has an extremely high mortality rate when not treated. This paper describes the aetiology, clinical manifestations and treatment of this disease and outlines the correct procedure for patients who are susceptible to a malignant hyperthermic crisis.

Development of malignant hyperthermia during mitral valve replacement

Malignant hyperthermia is a genetically predisposed, potentially fatal disorder triggered by anesthetic agents. The early diagnosis and treatment of malignant hyperthermia is essential, yet often difficult, because the signs and symptoms of this disorder are not unique to the disease. When the patient is also undergoing cardiopulmonary bypass this disorder may be very difficult to recognize. In this article, we report a case of malignant hyperthermia diagnosed during mitral valve replacement and discuss the preoperative and postoperative management possibilities. The unusualness of this case stems from the fact that the patient had centronuclear myopathy. Although reported with other types of myopathies, centronuclear myopathy has rarely been associated with malignant hyperthermia. This episode of malignant hyperthermia was diagnosed by intraoperative measurements showing increased oxygen consumption despite hypothermic cardiopulmonary bypass.

[Management of a patient with malignant hyperthermia susceptibility during anesthesia and daily living]

Death from malignant hyperthermia (MH) still occurs in France. However, anaesthesia of the MH susceptible (MhS) patient is quite possible without any more risk than for patients who are not MhS. Guidelines have been worked out: "trigger" drugs such as volatile anaesthetics (halothane, enflurane, isoflurane) and depolarizing muscle relaxants must be imperatively avoided; "non-trigger" drugs should be used, such as nitrous oxide, barbiturates, benzodiazepines, propofol, opiates, non-depolarizing muscle relaxants, amide or ester local anaesthetics at the usual doses without adrenaline. Moreover, dantrolene should be available in all hospitals, 12 bottles being a minimum at hand, or, better, 30 (about 10 mg.kg-1). In some cases, such as emergencies, an unprepared operating theatre, or an unprepared ventilator, the patient should be premedicated with 2.5 mg.kg-1 dantrolene intravenously. The ventilator, the circuit and the operating theatre should not contain any trace of halogenated vapour. The usual parameters, as well as temperature and expired CO2 concentration, should be closely monitored. MhS patients must also be given counselling. This includes explanations about MH, its genetic features, the main laboratory tests used to detect susceptibility, as well as advice about lifestyle, the use of drugs other than general and local anaesthetics, and a discussion concerning the association of MH with other diseases. This counselling is not always easy to provide, because many answers are not, as yet, definitive.

Rewarming following hypothermic cardiopulmonary bypass in the malignant hyperthermia-susceptible patient: implications for diagnosis and perioperative management

A 55-year-old, malignant hyperthermia-susceptible patient underwent myocardial revascularization without incident. Six hours postoperatively, he developed what was initially diagnosed as an MH crisis, for which he received intravenous dantrolene. The resultant muscle weakness prolonged the duration of postoperative mechanical ventilation and likely contributed to the development of a postoperative pneumonia. Plasma dantrolene levels were measured for the first 48 hours postoperatively and correlated with clinical findings. On reviewing the patient's perioperative course, it was felt that the hypermetabolic state was not due to MH. The patient's pattern of rewarming following hypothermic cardiopulmonary bypass was similar to non-MH-susceptible patients. Because of the difficulty in diagnosing a MH crisis after hypothermic bypass, it is recommended that patients receive prophylactic dantrolene preoperatively and after bypass. Nondepolarizing muscle relaxants should be given postoperatively to prevent shivering and respiratory acidosis while patients rewarm.

Development of malignant hyperthermia obscured by cardiopulmonary bypass

An episode of malignant hyperthermia occurring in a two-year-old child undergoing cardiac surgery is reported. The coincidental usage of hypothermic cardiopulmonary bypass obscured the classical presenting signs and symptoms of the syndrome. Once the clinical diagnosis was confirmed, rapid reversal was achieved with the administration of dantrolene sodium.