Ketamine does not trigger malignant hyperthermia in susceptible swine.

The use of ketamine in individuals susceptible to malignant hyperthermia (MH) is controversial. We describe our experience with ketamine used for induction and/or maintenance of anesthesia in our herd of swine inbred for susceptibility to MH. A total of 76 MH-susceptible swine were given a total of 112 general anesthetics using ketamine as the induction drug. In 34 of these anesthetics, anesthesia was also maintained with ketamine. Signs of MH did not develop in response to ketamine in any of the pigs.

The screening of propofol in MHS swine.

This study investigated the use of propofol in swine genetically susceptible to malignant hyperthermia (MH). Thirteen animals were exposed to 2% halothane in inspired air, a propofol infusion of 12 mg.kg-1.hr-1 for up to 45 min, or a combination of both. When MH was triggered the animals were treated with dantrolene. Mean onset time of malignant hyperthermia on exposure to halothane alone was 7.2 min +/- 3.0 min and onset with propofol and halothane was 5.0 +/- 2.5 min. In no instance did propofol alone trigger the syndrome nor was there a statistical difference (P less than 0.05) in onset time when the drug was used in conjunction with halothane. On the basis of these results, we conclude that propofol is almost certainly safe for use in humans who are susceptible to MH.

Effects of droperidol, haloperidol and ketamine on halothane, succinylcholine and caffeine contractures: implications for malignant hyperthermia.

The effects of two structurally similar butyrophenones (droperidol and haloperidol) and ketamine were evaluated in an in vitro system to determine their potential for eliciting or exacerbating an episode of malignant hyperthermia. Muscle strips from patients referred for diagnostic testing for malignant hyperthermia and muscle strips from the rat diaphragm were exposed to droperidol, haloperidol, or ketamine prior to challenge with halothane, succinylcholine or caffeine. If any agent augmented the contracture response to the malignant hyperthermia triggering or diagnostic agents, then the agent was considered unsafe for use in malignant hyperthermia susceptible patients. Droperidol 10 mumol/l and ketamine 100 mumol/l did not induce contractures in human or rat skeletal muscle when added alone, nor did they augment halothane, succinylcholine or caffeine contractures. These agents appear to be safe for use in patients susceptible to malignant hyperthermia. In contrast, haloperidol 10 mumol/l augmented the response to succinylcholine about 1.5-fold and may be contraindicated in MH susceptibles.

Malignant hyperthermia and the conscious patient.

A 53 year old obese male presented with the signs and symptoms of acute appendicitis and a family history suggesting the possibility of a malignant hyperthermia trait. In spite of spinal anaesthesia the patient developed malignant hyperthermia during the appendicectomy and the attack was successfully aborted with the early use of dantrolene sodium (Dantrium, Norwich Eaton).

Hipertermia maligna: a propósito de tres casos / Malignant hyperthermia: on purpose of thee clinical cases

3 pacientes sometidos a anestesia general (hombre 33 años por exploración testicular en 1983, hombre 34 años por amigdalectomía en 1986, adolescente de 13 años por osteosíntesis de hombro en 1987) presentan, al iniciar, o durante la anestesia, cuadros semejantes, caracterizados por fasciculaciones, contractura muscular, taquicardia, arritmias ventriculares, sudoración, alza de temperatura, cianosis, junto con acidosis metabólica y respiratoria, elevación de la creatin fosfoquinasa (CPK) y hemoglobinuria, en grados variables para cada caso. Se planteó Hipertermia Maligna y se le trató con antiarrítmicos, detención de la intervención quirúrgica, oxígeno 100%, soluciones parenterales heladas, diuréticos, lavados gástricos con hielo, Bicarbonato de Sodio y Dantrole Sódico E. V. Se trató también las complicaciones que surgieron como una Insuficiencia Renal Aguda y Edema Pulmonar. Los tres casos evolucionaron en forma satisfactoria con recuperación total sin secuelas

Cocaine intoxication: hyperpyrexia, rhabdomyolysis and acute renal failure.

Cocaine has become the recreational drug of abuse of the eighties. The prevalence of cocaine has been manifesting increases in intoxications and poisonings. Acute overdoses have been associated with hyperthermia, agitation, paranoid ideation, status epilepticus, ventricular fibrillation, ventricular tachycardia, myocardial infarction, coma, and death. This is the first reported case of cocaine intoxication resulting in severe hyperthermia, bizarre behavior, rhabdomyolysis, and acute renal failure. Treatment consisted of cooling via iced intravenous fluids, nasogastric lavage with ice water, and benzodiazepine sedation. To our knowledge, there is no case report which supports the allusions that cocaine intoxication may cause rhabdomyolysis and acute renal failure.

Malignant hyperthermia and ECT.

The malignant hyperthermia syndrome is a rare hypermetabolic state that occurs in patients after the administration of certain drugs, most frequently anesthetics and/or succinylcholine. In view of the widespread use of succinylcholine to induce muscle relaxation prior to ECT, it is important that the individual who administers succinylcholine in this setting be familiar with the syndrome and its treatment. This report reviews what is known about malignant hyperthermia and proposes a course of action when the syndrome occurs in a patient undergoing ECT or a patient with known susceptibility to malignant hyperthermia needs ECT.

A fatal case of malignant hyperthermia following isoflurane anaesthesia.

To date, only two cases of malignant hyperthermia following isoflurane anaesthesia have been reported, neither of which were fatal. This case describes a very malignant form of hyperthermia after isoflurane, in which the laboratory values were grossly abnormal, and with multi-organ failure and death finally supervening.

Suxamethonium chloride and malignant hyperpyrexia.

Pure suxamethonium chloride does not produce in vitro contracture of skeletal muscle from swine which are susceptible to malignant hyperpyrexia (MH), but does induce MH in vivo. It is suggested that suxamethonium chloride induces MH because the fasciculations which it causes lead to an increase in the myoplasmic calcium concentration.

The screening of atracurium in MHS swine.

The potential role of atracurium besylate as a trigger or attenuator of the malignant hyperthermia syndrome was tested in six MHS Landrace swine. Animals were tested for susceptibility and then exposed to atracurium given as an i.v. bolus both alone and concomitantly with 2% halothane. In no instance could the syndrome be triggered by atracurium nor did it convincingly attenuate the syndrome when triggered by halothane.

Verapamil is not a therapeutic adjunct to dantrolene in porcine malignant hyperthermia.

We have investigated the hypothesis that the calcium antagonist verapamil might be useful for prevention or treatment of malignant hyperthermia (MH) in MH-susceptible (MHS) swine. MH episodes were triggered in four groups of four swine with halothane alone or combined with succinylcholine (SCh) and, with and without verapamil. MH episodes were reversed by therapy with dantrolene and NaHCO3 in all groups. Verapamil did not alter MH episodes triggered by halothane alone or combined with SCh. The dantrolene-NaHCO3 requirements for reversal of MH were greater for the groups receiving halothane-SCh, but did not differ in groups pretreated with and without verapamil. In vitro verapamil (25 microM) did not reduce responses of intact muscle fibers to halothane and, in fact, exaggerated some halothane-induced responses. High concentrations of verapamil (0.5 mM) caused contractures in MHS but not in normal muscles. Neither our in vivo nor in vitro results support the use of verapamil in the treatment of MH. Further, doses of dantrolene used to reverse these MH episodes, although admittedly small (1-2 mg/kg), did not produce myocardial depression when used in combination with verapamil.

Relationships between the H and A-O blood types, phosphohexose isomerase and 6-phosphogluconate dehydrogenase red cell enzyme systems and halothane sensitivity, and economic traits in a superior and an inferior selection line of swiss landrace pigs.

Associations between production traits and the genes for halothane sensitivity (HAL), S, A and H blood group systems and phosphohexose isomerase (PHI) and 6-phosphogluconate dehydrogenase (6-PGD) enzyme systems were investigated in two lines of pigs selected for an index. The phenotypic variance-covariance matrix of the index included backfat thickness and daily gain, whereas the genetic variance-covariance matrix included daily gain, feed conversion and percentage of lean meat. The experiment was conducted at the experimental station of the Institute of Animal Production and has been underway since 1973. The same index was applied but in two opposite directions to give a superior and inferior line in relation to the production traits. One hundred twenty-nine animals of the superior line in the seventh generation and 88 animals of the inferior line in the sixth generation were studied. Forty-two percent (54/129) of the animals of the superior line were halothane-positive. No animals in the inferior line were halothane reactors. Of the halothane-positive pigs, 70.4% (38/54) in the superior line had the HaHa and 94.4% (51/54) had the SsSs genotype, whereas only 4% (3/75) of the HaHa and 12% (9/75) of the SsSs pigs were halothane-negative. By practicing selection at the H and S loci, it seems possible to efficiently reduce halothane sensitivity in Swiss Landrace pigs. In pigs of the superior line, there were significant differences in percentage of lean meat, carcass length, pH1 (pH value at 45 min to 1 h postmortem, M. longissimus) and reflectance values among genotypes of the HAL, S and H systems and among some genotypes of the 6-PGD system. Poorest meat quality, highest percentage of lean meat and shortest carcass length were observed in pigs homozygous for the alleles HALn, Ss, Ha, PHIB and 6-PGDA. In the inferior line, these associations were absent. As the HAL locus is associated with the above mentioned production traits, linkage disequilibria may explain the observed associations among the H, S, PHI and 6-PGD types and production traits.