Management of a malignant hyperthermia patient during cardiopulmonary bypass

Abstract

The anaesthetic management of cardiopulmonary bypass (CPB) for a patient with biopsy-proven malignant hyperthermia is reported. Specific changes in the technique used, such as venting the oxygenator before use, monitoring mixed venous Po: and Pco2, as well as the safety of cold hyperkalaemic cardioplegia are described. Controversial aspects of malignant hypet~hermia management such as the safety of calcium and catechol inotropes are discussed in relationship to the successful use of eardio-pulmonary bypass in our patient. We chose to treat left ventricular dysfunction by aggressive vasodilator (nitroglycerine) therapy. We detected no myocardial or respiratory depression secondary to dantrolene therapy either before or after operation.KEY WORDS" CARDIAC SURGERY, COMPLICATIONS, malignant hyperthermia.MALIGNANT HYPERTHERMIA (MH) is a pharmacogenetic myopathy I involving both skeletal 2 and cardiac muscle. 3 Affected patients are susceptible to acute hyperthermia and/or myotonic reactions triggered by several specific drugs, potent inhalational anaesthetics, some muscle relaxants, and the amide type of local anaesthetics. Reactions can be aggravated by sympathomimetics, parasympatholytics, cardiac glycosides and calcium salts. 4 Stressful environmental situations such as high temperatures, infections, muscle injury, exercise and emotional excitement may also precipitate a reaction. The pathophysiology of the hyperthermic crisis has been investigated and recently reviewed.4 The clinical and laboratory findings of human and porcine MH support the theory that the control of myoplasmic ionized calcium levels is lost, causing an increase in aerobic and anaerobic metabolism which characterizes the respiratory and metabolic acidosis of this syndrome.The purpose of this report is to outline the anaesthetic implications in a patient with MH and coronary artery disease requiring cardio- CASE REPORTA 54 year old male who had incapacitating angina at rest (Canadian Cardiovascular Society Class IV) 6 despite medical therapy (propranolal 160 mg/day) was admitted for coronary arteriography and elective triple aortocoronary bypass grafting. This patient had a strong family history of hyperthermic anaesthetic catastrophes and previously had been studied by muscle biopsy. The result 7 of both the caffeine contracture test and the ATP depletion test on the muscle biopsy specimen confirmed the diagnosis of MH.Cardiac catheterization was done using procaine for local anaesthesia while the patient was sedated with diazepam given intravenously. Temperature, electrocardiogram and arterial pressure were recorded continuously and precautions were taken to prevent and, if necessary, to treat an MH crisis during the heart catheterization. The selective coronary arteriograms showed severe triple vessel coronary artery disease including a lesion (>90 per cent occlusion) of the left main and right coronary artery. Left ventricular end diastolic pressure was 1.46 kPa (11 mm Hg) and the left ventricular ejection fraction was 67 per cent. T...

Sevoflurane‐induced malignant hyperthermia during cardiopulmonary bypass and moderate hypothermia

“…Cardiopulmonary bypass (CPB) and moderate hypothermia during CPB can obscure the clinical signs of MH and make the diagnosis difficult. The development of MH during cardiopulmonary bypass (CPB) is rare (1–5). Several reported cases are doubtful due to lack of biopsies (1–4).…”

“…The development of MH during cardiopulmonary bypass (CPB) is rare (1–5). Several reported cases are doubtful due to lack of biopsies (1–4). We report a case of unexpected MH due to sevoflurane in an adult patient during CPB.…”

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

“…[ 7 ] Out of the 24 cases in the review, 14 patients experienced an MH event, whereas 10 did not. [ 8 9 10 11 12 13 14 15 16 17 ] Of the 14 patients who experienced MH episodes, 10 were attributed to the use of volatile agents. [ 18 19 20 21 22 23 24 25 ] The triggering agent for the other 4 patients remained unknown, however, no known triggering anesthetic agents were used.…”

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

“…Byrick et al 13 questioned if the muscle weakness induced by dantrolene might precipitate respiratory muscle fatigue postoperatively. In their case report of a MHS patient who underwent coronary artery bypass grafting with hypothermic CPB, the postoperative course was uneventful and there was no significant impairment of respiratory function.…”