Presence of two different genetic traits in malignant hyperthermia families: implication for genetic analysis, diagnosis, and incidence of malignant hyperthermia susceptibility.

Background: Malignant hyperthermia susceptibility (MHS), an uncommon syndrome often inherited as an autosomal dominant trait, is characterized by a genetic and clinical heterogeneity. In this article, the authors described six pedigrees in which both parents of MHS patients were diagnosed with MHS by an diagnostic test. Haplotype and mutation analysis revealed that more than one MHS genetic trait was present in these families.

Shortening velocity of skeletal muscle from humans with malignant hyperthermia susceptibility: effects of halothane.

The aim of this investigation was to assess the effect of halothane on the velocity of shortening and lengthening of muscle from normal subjects and from patients with malignant hyperthermia susceptibility. Strips were mounted horizontally at optimal length in normal Krebs-Ringer's solution and mechanical parameters were obtained before and after exposure to 3 vol.% halothane.

A new noninvasive method to measure blood pressure: results of a multicenter trial.

Background: Blood pressure (BP) monitoring with arterial waveform display requires an arterial cannula. We evaluated a new noninvasive device, Vasotrac (Medwave, Arden Hills, MN) that provides BP measurements approximately every 12-15 beats and displays pulse rate and a calibrated arterial waveform for each BP measurement.

Methods: Surgical and critically ill patients (n = 80) served as subjects for the study.

ATX II, a sodium channel toxin, sensitizes skeletal muscle to halothane, caffeine, and ryanodine.

Background: The function or expression of subtypes of the sodium ion (Na+) channel is altered in biopsies or cultures of skeletal muscle from many persons who are susceptible to malignant hyperthermia (MH). ATX II, a specific Na+ channel toxin from a sea anemone, causes delayed inactivation of the channel similar to that seen in cell cultures of MH muscle. ATX II was added to skeletal muscle to determine whether altered Na+ channel function could increase the sensitivity of normal skeletal muscle to agents (halothane, caffeine, ryanodine) to which MH muscle is hypersensitive.

Halothane induces calcium release from human skinned masseter muscle fibers.

Background: An increase in masseter muscle tone in response to halothane or succinylcholine anesthesia (or both) can be observed in healthy persons. Thus the authors compared the fiber-type halothane and succinylcholine sensitivities in human masseter and vastus lateralis muscles.

Methods: Masseter and vastus lateralis muscle segments were obtained from 13 and 9 healthy persons, respectively.

[-The clinical use of the cuffed oropharyngeal airway (COPA)-].

Objective: To assess the performance of the COPA device during general anaesthesia.

Study Design: Prospective, clinical, open study.

Patients: Eighty patients scheduled for short elective surgical procedures under general anaesthesia not requiring tracheal intubation.

Effects of veratridine on mechanical responses of human malignant hyperthermic muscle fibers.

Background: To determine if alteration in the function of the sodium channel may in turn modify halothane-induced changes in mechanical responses of muscle bundles from patients susceptible to malignant hyperthermia (MH).

Methods: Mechanical responses of muscle bundles from 12 MH-susceptible and 20 MH non-susceptible patients were measured prior to and during administration of halothane alone and in the presence of 10 microM veratridine, an inhibitor of sodium channel inactivation. Peak tension (PT), time to peak tension (TPT), positive peak of isometric tension derivative (+dP/dtmax) were used to characterize the inotropic state.

Identification of heterozygous and homozygous individuals with the novel RYR1 mutation Cys35Arg in a large kindred.

Background: Malignant hyperthermia (MH) is a potentially fatal, often autosomal dominant, disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anesthetics. In this article, the authors describe a malignant hyperthermia susceptible (MHS) kindred in which both parents of the proband are MHS and are first-degree cousins. Haplotype analysis in this kindred with chromosome 19 linked markers revealed that the proband and another sibling were homozygous for the affected RYR1 allele.

In vitro human masseter muscle hypersensitivity: a possible explanation for increase in masseter tone.

To determine whether a difference in fiber-type caffeine and Ca2+ sensitivities exists between human masseter and vastus lateralis skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers from 13 masseter and 18 vastus lateralis muscles. Caffeine sensitivity was defined as the threshold concentration inducing > 10% of the maximal tension obtained after the fiber was loaded with a 1.6 x 10(-2) mM Ca2+ solution for 30 s.

Isoform-dependent effects of halothane in human skinned striated fibers.

Background: Reports of the effects of halothane on isoform contractile proteins of striated muscles are conflicting. To determine whether halothane affects cardiac and skeletal contractile proteins differently, the authors examined the effects of two doses of halothane (0.44 and 1.

Evaluation of the Augustine Guide for difficult tracheal intubation.

Successful tracheal intubation with Augustine Guide (Augustine Medical, Inc., Eden Prairie, MN) in patients with normal airways has recently been described. There are no studies describing Augustine Guide (AG) use in patients with difficult airways.

[Cervicofacial cellulitis of dental origin and tracheal intubation].

Objectives: To evaluate the difficulty of intubation in relation with the localisation and spread of cervico-facial cellulitis of odontogenic origin and to recognize the optimal technique of intubation in such circumstances.

Study Design: Prospective clinical open study.

Patients: Hundred patients, including 16 children, undergoing surgical drainage of a cervico-facial cellulitis of odontogenic origin under general anesthesia were studied.

Intermittent left bundle branch block revealed during anaesthesia.

Intermittent left bundle branch block is uncommon. During anaesthesia,, left bundle branch block may be related to hypertension or tachycardia and its occurrence makes the diagnosis of acute myocardial ischaemia or infarction difficult. Patients with intermittent left bundle branch block often develop established left bundle branch block, which may represent an earlier state of ischaemic heart disease.

Halothane and isoflurane decrease calcium sensitivity and maximal force in human skinned cardiac fibers.

Background: Reports of the direct effects of volatile anesthetics on cardiac myofibrils, studied in various mammalian species but not in humans, have conflicted. To determine whether volatile anesthetics directly affect cardiac contractile proteins in humans, we examined the effects of various equianesthetic doses of halothane (0.46, 0.

Viability criterion of muscle bundles used in the in vitro contracture test in patients with neuromuscular diseases.

We have compared the viability criteria of muscle bundles used in the in vitro contracture test for susceptibility to malignant hyperthermia (MH) in a group of 28 patients with various neuromuscular diseases (NMD) and 93 MH-related family patients. In the patients with NMD, this standard test gave one positive, six equivocal and 21 negative results. Compared with MH-related family patients, muscle bundles used had significantly smaller resting membrane potentials and smaller predrug twitch tension amplitudes.

[Lack of sensitivity to per-anesthetic malignant hyperthermia in 32 patients who developed neuroleptic malignant syndrome].

The aim of this study was to verify whether a relationship exists between neuroleptic malignant syndrome (NMS) and anaesthetic-induced malignant hyperthermia (MH) or not. The in vitro halothane-caffeine tests were performed on muscle tissue obtained from 32 patients with documented NMS episodes. The diagnosis of NMS relied on Levenson's criteria.

Fiber-type caffeine sensitivities in skinned muscle fibers from humans susceptible to malignant hyperthermia.

Background: The response to contracture tests may depend upon the relative proportion of muscle fiber types within the muscle specimen. To determine whether a difference in fiber-type caffeine sensitivities exists between malignant hyperthermia susceptible (MHS) and malignant hyperthermia-nonsusceptible (MHN) skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers dissected from vastus lateralis muscle from 15 MHS and 16 MHN patients.

Methods: Muscle fiber type was determined in each fiber by the difference in strontium-induced tension measurements and in 36 fibers, after contracture testing, by ATPase enzyme histochemistry.

Effect of Bay K 8644 on the magnitude of isoflurane and halothane contracture of skeletal muscle from patients susceptible to malignant hyperthermia.

Isoflurane has a lesser ability than halothane to induce contracture in malignant hyperthermia (MH) muscle in vitro. This does not necessarily imply that isoflurane is not as potent an MH trigger as halothane in vivo. A hypothesis was tested that in vitro treatment with Bay K 8644, an activator of both the dihydropyridine receptors as well as the sodium channels of the T-tubules, potentiates isoflurane-induced MH-susceptible skeletal muscle contracture.

Is resting membrane potential a possible indicator of viability of muscle bundles used in the in vitro caffeine contracture test?

In 22 patients susceptible to and 34 patients not susceptible to malignant hyperthermia, we examined which muscle conditions may influence the degree of sensitivity of skeletal muscle to the in vitro caffeine contracture test: predrug resting membrane potential, predrug twitch tension, and maximum contracture induced by 32 mM caffeine in two caffeine tests performed respectively at 30 and 75 min after biopsy. No differences in the measured variables were observed between the first and the second caffeine tests in the 34 patients susceptible to malignant hyperthermia. The first caffeine test was found to be positive in all of the 22 patients susceptible to malignant hyperthermia.

Effects of calcium-free solution, calcium antagonists, and the calcium agonist BAY K 8644 on mechanical responses of skeletal muscle from patients susceptible to malignant hyperthermia.

The purpose of this investigation was to determine if alteration in the function of the dihydropyridine receptor may in turn modify halothane-induced contractures in muscle bundles from patients susceptible to malignant hyperthermia (MH). The effects of Ca(2+)-free Krebs Ringer (KR) solution, 5 microM verapamil, 5 microM nifedipine, and 10 microM of the Ca2+ agonist BAY K 8644 on halothane-induced contracture were therefore investigated. The halothane-induced contracture was prevented in the absence of extracellular Ca2+ and significantly reduced in the presence of verapamil or nifedipine.

Diltiazem and nifedipine reduce the in vitro contracture response to halothane in malignant hyperthermia-susceptible muscle.

The effects of diltiazem (1 microM) and nifedipine (1 microM) were examined separately on the in vitro halothane tests for malignant hyperthermia (MH) susceptibility. Eighteen patients with MH susceptibility were diagnosed as MH-susceptible (MHS) according to the protocol of the European MH Group. In addition, halothane tests were carried out in the presence of either diltiazem (ten patients) or nifedipine (eight patients).