A comprehensive review of malignant hyperthermia: Preventing further fatalities in orthopedic surgery

Relevance of pharmacogenetics and pharmacogenomics in veterinary clinical practice: A review

The recent advances in high-throughput next-generation sequencing technologies have heralded the arrival of the Big Data era. As a result, the use of pharmacogenetics in drug discovery and individualized drug therapy has transformed the field of precision medicine. This paradigm shift in drug development programs has effectively reshaped the old drug development practices, which were primarily concerned with the physiological status of patients for drug development. Pharmacogenomics bridges the gap between pharmacodynamics and pharmacokinetics, advancing current diagnostic and treatment strategies and enabling personalized and targeted drug therapy. The primary goals of pharmacogenetic studies are to improve drug efficacy and minimize toxicities, to identify novel drug targets, to estimate drug dosage for personalized medicine, and to incorporate it as a routine diagnostic for disease susceptibility. Although pharmacogenetics has numerous applications in individualized drug therapy and drug development, it is in its infancy in veterinary medicine. The objective of this review is to present an overview of historical landmarks, current developments in various animal species, challenges and future perspectives of genomics in drug development and dosage optimization for individualized medicine in veterinary subjects.

Brief isoflurane administration as an adjunct treatment to control organophosphate-induced convulsions and neuropathology

Organophosphate-based chemical agents (OP), including nerve agents and certain pesticides such as paraoxon, are potent acetylcholinesterase inhibitors that cause severe convulsions and seizures, leading to permanent central nervous system (CNS) damage if not treated promptly. The current treatment regimen for OP poisoning is intramuscular injection of atropine sulfate with an oxime such as pralidoxime (2-PAM) to mitigate cholinergic over-activation of the somatic musculature and autonomic nervous system. This treatment does not provide protection against CNS cholinergic overactivation and therefore convulsions require additional medication. Benzodiazepines are the currently accepted treatment for OP-induced convulsions, but the convulsions become refractory to these GABAA agonists and repeated dosing has diminishing effectiveness. As such, adjunct anticonvulsant treatments are needed to provide improved protection against recurrent and prolonged convulsions and the associated excitotoxic CNS damage that results from them. Previously we have shown that brief, 4-min administration of 3%-5% isoflurane in 100% oxygen has profound anticonvulsant and CNS protective effects when administered 30 min after a lethal dose of paraoxon. In this report we provide an extended time course of the effectiveness of 5% isoflurane delivered for 5 min, ranging from 60 to 180 min after a lethal dose of paraoxon in rats. We observed substantial effectiveness in preventing neuronal loss as shown by Fluoro-Jade B staining when isoflurane was administered 1 h after paraoxon, with diminishing effectiveness at 90, 120 and 180 min. In vivo magnetic resonance imaging (MRI) derived T2 and mean diffusivity (MD) values showed that 5-min isoflurane administration at a concentration of 5% prevents brain edema and tissue damage when administered 1 h after a lethal dose of paraoxon. We also observed reduced astrogliosis as shown by GFAP immunohistochemistry. Studies with continuous EEG monitoring are ongoing to demonstrate effectiveness in animal models of soman poisoning.

Creation and Implementation of a Preoperative Malignant Hyperthermia Screening Tool

BACKGROUND

Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disorder triggered by certain anesthetic agents. There is currently no standardized preoperative screening tool utilized to identify MH-susceptible individuals.

LOCAL PROBLEM

This quality improvement (QI) project aimed to enhance preoperative screening for MH susceptibility (MHS) by implementing an evidence-based screening tool for surgical patients at 2 sites.

METHODS

This prospective descriptive QI project evaluated the success of implementing an MHS screening tool preoperatively and its impact on the anesthesia plan.

INTERVENTIONS

Anesthesia professionals included the screening tool in their preoperative interview for surgical patients so that positively screened patients could receive MH prevention measures.

RESULTS

A total of 95 patients at site A and 234 patients at site B were screened using the MH tool, a cumulative total of 21 patients were positively screened, and 1 anesthetic plan was altered.

CONCLUSIONS

This MHS screening tool has the potential to prevent MH episodes when used consistently by staff.

Delayed-onset malignant hyperthermia in the postanesthetic care unit: a case report

Malignant hyperthermia (MH) is a potentially fatal hypermetabolic syndrome that occurs when susceptible individuals are exposed to triggering agents. Variability in the order and time of occurrence of symptoms often makes clinical diagnosis difficult. A late diagnosis or misdiagnosis of delayed-onset MH may lead to fatal complications. We herein report a case of delayed-onset MH in the postoperative recovery room. A 77-year-old man awoke from anesthesia and was transferred to the recovery room. Ten minutes after his arrival, his mental status became stuporous and he developed masseter muscle rigidity, hyperventilation, and a body temperature of 39.8°C. The patient was suspected to have MH, and 60 mg of dantrolene sodium (1 mg/kg) was administered via intravenous drip with symptomatic treatment. Within 10 minutes of dantrolene administration, the patient's clinical signs subsided. This case report demonstrates that rapid diagnosis and treatment are crucial to ensure a good prognosis for patients with MH. A high level of suspicion based on clinical symptoms and early administration of therapeutic drugs such as dantrolene will also improve the clinical course. Therefore, suspicion and prompt diagnosis are absolutely essential. This case report emphasizes the importance of continuous education in the diagnosis and treatment of MH.

Malignant Hyperthermia Syndrome: A Clinical Case Report

Malignant hyperthermia is a pharmacogenetic disorder. It manifests as a hypercatabolic skeletal muscle syndrome linked to inhaled volatile anesthetics or depolarizing muscle relaxants. Its clinical signs and symptoms are tachycardia, hyperthermia, hypercapnia, acidosis, muscle rigidity, rhabdomyolysis, hyperkalemia, arrhythmia and renal failure. Mortality without specific treatment is 80% and decreases to 5% with the use of dantrolene sodium. This article presents the case of a 39-year-old patient admitted to the Intensive Care Unit for malignant hyperthermia after surgery for septoplasty plus turbinoplasty.

Malignant Hyperthermia in Bariatric Surgery: A Case Study With Clinical, Pathophysiological, Biochemical and Biophysical Correlations

Malignant hyperthermia (MH) is an acute pharmacogenetic disorder, which while uncommon is potentially fatal. MH is a calcium channelopathy of skeletal muscle in which a constant increase of intracytoplasmic Ca2+ concentration occurs causing a change in cellular metabolism. A hypermetabolic state develops when susceptible patients are exposed to halogenated volatile inhalational anesthetic agents and depolarizing muscle relaxants and/or extreme physical activity in hot environments. MH presents variable clinical expression. During an episode of MH, the patient may present clinical signs and laboratory findings including masseter muscle spasm, tachycardia, rise in end-tidal CO2 (EtCO2), tachypnea, hyperthermia, cyanosis, metabolic acidosis, rhabdomyolysis, hyperkalemia, myoglobinuria, hyperlactacidemia, and acute renal failure. The aim of this case report is to describe an episode of MH associated with the use of halogenated anesthetic during bariatric surgery. A 29-year-old Brazilian man was admitted to the hospital to undergo a bariatric surgery. The patient's relevant medical history included morbid obesity grade III, allergy to sulfa-based drugs and severe obstructive sleep apnea. Preoperative evaluations with cardiopulmonary exercise testing, echocardiogram and electrocardiogram showed no anatomical and functional changes of the patient's heart. Surgical procedures lasted for 4 h, without complications, but the evolution of the patient's condition indicated oliguria and acute breathing insufficiency. Five hours after the patient was placed under mechanical ventilation in the intensive care unit, he started to present clinical signs of hypermetabolic state, with tremors, excessive sweating, and rapid body temperature increases. In the postoperative period, the patient had hyperglycemia, hypocalcemia, hypernatremia, hyperkalemia, changes in creatine phosphokinase (CPK), aspartate transaminase (AST), alanine aminotransferase (ALT), urea and creatine concentrations, and metabolic and respiratory acidosis. Urinalysis showed traces of proteinuria, presence of ketones, leukocytes, red blood cells, and urobilinogen. In our case report, MH crisis was diagnosed late; the dantrolene was not administrated because it was not available and the patient died. This detailed case report of MH episode triggered by isoflurane anesthetic during bariatric surgery allowed us to describe the severity and lethality of this hypermetabolic syndrome. Dantrolene should be mandatory in all operating rooms. Knowledge of the symptoms, an early diagnosis and an adequate treatment can prevent the death of patients in MH crisis.

Nursing Interventions of Intraoperative Malignant Hyperthermia in Patients With Scoliosis: A Report of 3 Cases

INTRODUCTION

The report summarizes the intraoperative rescue and nursing intervention of malignant hyperthermia (MH) in the correction surgery for 3 patients with spinal deformity. Although rare, MH may occur in up to 1 of 5000 cases.

INTERVENTION

The key points of nursing care include preoperative MH risk assessment, MH early warning, cessation of anesthetic, use of a validated scoring system, and initiation of cooling measures.

CONCLUSION

Prompt nursing recognition and team-fcoused interventions provided successful rescue of 3 patients with MH.

Non-traumatic and non-drug-induced rhabdomyolysis

Rhabdomyolysis (RM), a fortunately rare disease of the striated muscle cells, is a complication of non-traumatic (congenital (glycogen storage disease, discrete mitochondrial myopathies and various muscular dystrophies) or acquired (alcoholic myopathy, systemic diseases, arterial occlusion, viral illness or bacterial sepsis)) and traumatic conditions. Additionally, RM can occur in some individuals under specific circumstances such as toxic substance use and illicit drug abuse. Lipid-lowering drugs in particular are capable of causing RM. This comprehensive review will focus on non-traumatic and non-drug-induced RM. Moreover, the pathology of RM, its clinical manifestation and biochemical effects, and finally its management will be discussed.

Translating Pharmacogenetics and Pharmacogenomics to the Clinic: Progress in Human and Veterinary Medicine

As targeted personalized therapy becomes more widely used in human medicine, clients will expect the veterinary clinician to be able to implement an evidence-based strategy regarding both the prescribing of medicines and also recognition of the potential for adverse drug reactions (ADR) for their pet, at breed and individual level. This review aims to provide an overview of current developments and challenges in pharmacogenetics in medicine for a veterinary audience and to map these to developments in veterinary pharmacogenetics. Pharmacogenetics has been in development over the past 100 years but has been revolutionized following the publication of the human, and then veterinary species genomes. Genetic biomarkers called pharmacogenes have been identified as specific genetic loci on chromosomes which are associated with either positive or adverse drug responses. Pharmacogene variation may be classified according to the associated drug response, such as a change in (1) the pharmacokinetics; (2) the pharmacodynamics; (3) genes in the downstream pathway of the drug or (4) the effect of “off-target” genes resulting in a response that is unrelated to the intended target. There are many barriers to translation of pharmacogenetic information to the clinic, however, in human medicine, international initiatives are promising real change in the delivery of personalized medicine by 2025. We argue that for effective translation into the veterinary clinic, clinicians, international experts, and stakeholders must collaborate to ensure quality assurance and genetic test validation so that animals may also benefit from this genomics revolution.