Malignant hyperthermia

Life-threatening Episodes of Malignant Hyperthermia Following Halothane Anesthesia in Three Children: A Case Series and Review of Literature

Malignant hyperthermia (MH) is an inherited, pharmacogenetic disorder of the skeletal muscle, characterized by dangerous hypermetabolic state after anesthesia with succinylcholine and/ or volatile halogenated anesthetic agents, clinically manifested as hyperpyrexia and related complications like tachycardia, tachypnea, increased carbon dioxide production, increased oxygen consumption, acidosis, rigid muscles, rhabdomyolysis and disseminated intravascular coagulation (DIC). Here we present a series of three cases of MH, admitted in our hospital in a span of 8 months for three different operative procedures to be done under general anesthesia (cleft lip repair, Duhamel's operation for Hirschsprung's disease and surgical repair of development dysplasia of hip), who developed probable hyperthermia owing to Halothane being used as an anesthetic agent.

How to cite this article

Laha S, Giri PP, Saha A, Gupta PP, De A. Life-threatening Episodes of Malignant Hyperthermia Following Halothane Anesthesia in Three Children: A Case Series and Review of Literature. Indian Journal of Critical Care Medicine, January 2019;23(1):47-50.

Crisis checklists for the operating room: development and pilot testing

BACKGROUND

Because operating room crises are rare events, failure to adhere to critical management steps is common. We sought to develop and pilot a tool to improve adherence to lifesaving measures during operating room crises.

STUDY DESIGN

We identified 12 of the most frequently occurring operating room crises and corresponding evidence-based metrics of essential care for each (46 total process measures). We developed checklists for each crisis based on a previously defined method, which included literature review, multidisciplinary expert consultation, and simulation. After development, 2 operating room teams (11 participants) were each exposed to 8 simulations with random assignment to checklist use or working from memory alone. Each team managed 4 simulations with a checklist available and 4 without. One of the primary outcomes measured through video review was failure to adhere to essential processes of care. Participants were surveyed for perceptions of checklist use and realism of the scenarios.

RESULTS

Checklist use resulted in a 6-fold reduction in failure of adherence to critical steps in management for 8 scenarios with 2 pilot teams. These results held in multivariate analysis accounting for clustering within teams and adjusting for learning or fatigue effects (11 of 46 failures without the checklist vs 2 of 46 failures with the checklist; adjusted relative risk = 0.15, 95% CI, 0.04-0.60; p = 0.007). All participants rated the overall quality of the checklists and scenarios to be higher than average or excellent.

CONCLUSIONS

Checklist use can improve safety and management in operating room crises. These findings warrant broader evaluation, including in clinical settings.

Preventability of drug-related harms - part II: proposed criteria, based on frameworks that classify adverse drug reactions

BACKGROUND

'Preventability' is a crucial concept in the literature on adverse drug effects. However, a systematic review of the definitions of preventability of adverse drug effects has suggested that none fits all circumstances. Furthermore, when the reliability of these definitions has been examined they have been found to be imperfect.

OBJECTIVE

To propose and outline a method for determining the theoretical preventability of an adverse drug effect, based on frameworks for classifying adverse drug reactions - the EIDOS and DoTS methods.

METHODS

EIDOS is based on the mechanism of action of the drug. It observes that a drug (an Extrinsic species) causes an adverse effect by interacting with an Intrinsic species that is its target when the two are Distributed together, and that the resulting pathophysiological Outcome (the adverse effect) causes the Sequela (the adverse reaction). DoTS observes that the Dose-relatedness of the adverse effect compared with the beneficial effect is relevant (determining toxic, collateral, or hypersusceptibility effects), that adverse effects have Time-courses (varying from immediate to delayed), and that there are individual Susceptibility factors.

RESULTS AND DISCUSSION

We have elicited many published examples that show that each of these factors in the causation of an adverse drug effect can be adduced to assess its preventability. We have constructed a flowchart that illustrates how the processes can be logically analysed.

CONCLUSIONS

This approach suggests methods for devising prospective preventive strategies and for deciding retrospectively whether an adverse reaction in an individual should have been prevented.

Follow-up of patients tested for malignant hyperthermia susceptibility

BACKGROUND AND OBJECTIVE

Malignant hyperthermia is an inherited disorder of skeletal muscle characterized by muscle contracture and hypermetabolic crisis following exposure to halogenated anaesthetics and depolarizing muscle relaxants. We planned this follow-up to get more information about the safety of non-triggering anaesthesia in susceptible patients; the safety of the use of trigger agents in non-susceptible patients and any minor sequelae following the biopsy.

METHODS

A questionnaire was sent to 244 patients tested for susceptibility between 1998 and 2004 enquiring about sequelae from the biopsy, subsequent experience with anaesthesia and difficulties encountered because of the investigation.

RESULTS

Replies were received from 129 patients. Thirty-four complained about sequelae from the biopsy: 10 reported headache and nausea; 16 experienced pain and a lack of strength in the biopsed leg and 8 found the scar less than satisfactory. Ten patients found it difficult to find a diagnostic centre. Eighteen reported problems and/or delay when they had needed a subsequent anaesthetic. Fourteen patients found the anaesthesiologist reluctant to anaesthetize them and four experienced a delay. Forty-three patients received anaesthesia since their biopsy. Complete medical records were available for 24 anaesthetic exposures in 23 patients. No documented perioperative complications occurred. Only three non-susceptible patients received one trigger agent.

CONCLUSIONS

It is safe to use trigger-free anaesthesia in susceptible patients. The difficulties encountered by patients to be anaesthetized and the management of the majority of non-susceptible patients during general anaesthesia show the need of more accurate educational programmes and methods for promoting patient-centred care.

Malignant hyperthermia

Malignant hyperthermia (MH) is an uncommon, life-threatening, acute pharmacogenetic disorder of the skeletal muscle cell. It manifests in susceptible individuals as a hypermetabolic response on exposure to halogenated volatile anaesthetics and depolarizing muscle relaxants. There may also be a relationship between susceptibility to MH, heat stroke and exercise-induced rhabdomyolysis. The pathophysiology of the crisis involves an uncontrolled release of cytoplasmic free calcium from the sarcoplasmic reticulum leading to activation of energy-producing biochemical pathways. Organ system failure and rhabdomyolysis may occur as a result of high fever, hyperkalaemia and acidosis. The ryanodine receptor, the calcium-release channel of the sarcoplasmic reticulum, is the primary locus for malignant hypothermia susceptibility. Multiple mutations in the gene for the ryanodine receptor protein are causative. Other genes may also be involved. A classical fulminant crisis presents with a rising end-tidal carbon dioxide, skeletal muscle rigidity, tachycardia, hyperthermia and acidosis. Mortality may be as high as 70% if the syndrome is not recognized and treated. Immediate discontinuation of triggering agents, oxygenation, and correction of acidosis and electrolyte abnormalities, cooling and dantrolene are essential for treatment of the syndrome. Thanks to clinical and research investigations, widespread education and the introduction of dantrolene sodium, the mortality from MH is less than 5%. This chapter provides an overview and an update of MH.

Drug-induced hyperthermia and muscle rigidity: a practical approach

Body thermoregulation can be violently offset by drugs capable of altering the balance between heat production and dissipation. Such events may rapidly become fatal. The drugs that are involved in the eruption of such syndromes include inhalation anaesthetics, sympathomimetic agents, serotonin antagonists, antipsychotic agents and compounds that exhibit anticholinergic properties. The resultant hyperthermia is frequently accompanied by an intense skeletal muscle hypermetabolic reaction that leads to rapidly evolving rigidity, extensive rhabdomyolysis and hyperkalemia. The differential diagnosis should, however, rule out non-drug-induced causes, such as lethal catatonia, central nervous system infection or tetanus, strychnine poisoning, thyrotoxic storm and pheochromocytoma. Prompt life-saving procedures include aggressive body temperature reduction. Patients with a suspected drug (or non-drug) hypermetabolic reaction should be admitted into an intensive care area for close monitoring and system-oriented supportive treatment. We present six conditions, in decreasing order of gravity and potential lethality, in which hyperthermia plays an essential role, and suggest a clinical approach in such conditions.

Current concepts in malignant hyperthermia

Malignant hyperthermia (MH) is a rare, potentially lethal, clinically and genetically heterogeneous pharmacogenic myopathy, which during or after general anesthesia manifests as MH crisis (MHC) in genetically predisposed, but otherwise mostly normal, individuals (MH susceptibles) in response to anesthetic-triggering agents. MHC can also occur in patients with central core disease. MCH-like crises have been reported in those with Duchenne/Becker muscular dystrophy, myotonic dystrophy, mitochondriopathy, and various other conditions. MH susceptibility is diagnosed if there is an MHC in the individual or family history or by the in vitro caffeine-halothane contracture test. Although screening for mutations in the ryanodine-receptor-1 gene and the dihydropyridine-receptor gene, respectively, could further substantiate the diagnosis, the caffeine-halothane-contracture test still remains the gold standard for diagnosing MH susceptibility. The most well-known triggers of an MHC are depolarizing muscle relaxants and volatile anesthetics. Therapy of an MHC comprises discontinuation of triggering agents, oxygenation, and correction of the acidosis and electrolyte disturbances, treatment of arrhythmias, cooling, and dantrolene. If MH susceptibility is not known preoperatively and an MHC unexpectedly interrupts anesthesia, consultation by a specialist in MH susceptibility after anesthesia is essential to investigate the patient for MH susceptibility or subclinical myopathy, guide laboratory investigations, manage therapy, and counsel the family on further risk. To further reduce morbidity and mortality of those with MHC, anesthesiologists and neurologists should be well educated and should strengthen their clinical vigilance. Research should be intensified and extended with regard to the development of new in vitro tests to further elucidate the heterogeneous genetic background of MH susceptibility.

Acp. Best practice no 155. Pathological investigation of deaths following surgery, anaesthesia, and medical procedures

The pathological investigation of deaths following surgery, anaesthesia, and medical procedures is discussed. The definition of "postoperative death" is examined and the classification of deaths following procedures detailed. The review of individual cases is described and the overall approach to necropsy and interpretation considered. There are specific sections dealing with the cardiovascular system (including air embolism, perioperative myocardial infarction, cardiac pacemakers, central venous catheters, cardiac surgery, heart valve replacement, angioplasty, and vascular surgery); respiratory system (postoperative pneumonia, pulmonary embolism, pneumothorax); central nervous system (dissection of cervical spinal cord), hepatobiliary and gastrointestinal system; musculoskeletal system; and head and neck region. Deaths associated with anaesthesia are classified and the specific problems of epidural anaesthesia and malignant hyperthermia discussed. The article concludes with a section on the recording of necropsy findings and their communication to clinicians and medicolegal authorities.

Medical treatment of a grossly enlarged adenomyotic uterus with the levonorgestrel-releasing intrauterine system

Adenomyosis is an important cause of menorrhagia. Besides hysterectomy, the treatment options for adenomyosis have been limited. Presented here is the successful treatment of adenomyosis in a woman presenting with menorrhagia, dysmenorrhea, and an enlarging uterus, for whom conservative therapy initiated with mefenamic acid was unsatisfactory. The patient had insertion of the levonorgestrel-releasing intrauterine system (LNG-IUS). A marked decrease in uterine size occurred within 12 months of insertion accompanied by resolution of the menorrhagia and dysmenorrhea. Thus, the LNG-IUS is a viable option and represents a real advance in the treatment of adenomyosis.

Malignant hyperthermia: advances in diagnostics and management

Real-time monitoring of end-tidal carbon dioxide during anaesthesia aids in the early detection of malignant hyperthermia and the occurrence of a rapid increase in end-tidal carbon dioxide, associated with unexplained persistent tachycardia, well before the core temperature begins to rise. Should malignant hyperthermia occur, however, dantrolene permits the dependable reversal of skeletal muscle hypermetabolism.