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At least 127 records · Page 7Linked to original sources
PubMed1999

The effect on intraocular pressure of endotracheal intubation or laryngeal mask use during TIVA without the use of muscle relaxants.

BACKGROUND: Depolarizing and non-depolarizing muscle relaxants possess many untoward side effects. In most patients endotracheal intubation may be performed with a propofol and alfentanil combination. The purpose of this study was to compare the effect on intraocular pressure (IOP) and haemodynamics of endotracheal (ET) intubation or laryngeal mask (LMA) insertion during total intravenous anaesthesia (TIVA) without the use of muscle relaxants. METHODS: In a randomised study, 20 patients scheduled for elective orthopaedic surgery were assigned to two groups of 10 patients. Anaesthesia was induced with i.v. alfentanil 40 micrograms/kg and propofol 2.5 mg/kg. LMA insertion or ET intubation was achieved by the same anaesthesiologist. Airway score, insertion score, patient response and haemodynamics were recorded. IOP measurements were recorded before and after induction, 1 and 2 min after ET intubation or LMA insertion, and 1 and 2 min after extubation. RESULTS: Mean arterial pressure and heart rate after insertion of the airway management devices was significantly higher than induction values in the ET group (P < 0.05), while during 2-3 min no significant changes were observed in LMA group. In all patients following propofol and alfentanil induction, IOP was significantly lower than preinduction values (P < 0.001). IOP following extubation was significantly higher than preinduction values in the ET group, but not in the LMA group (P < 0.001). CONCLUSION: During TIVA without the use of muscle relaxants neither LMA insertion nor ET intubation increased the IOP, but ET extubation did.

Adult↗
PubMed2003

[Application of muscle relaxants in Germany. A survey of German anaesthesia departments].

AIM: The aim of this study was to evaluate the use and application of muscle relaxants and neuromuscular monitoring in Germany. METHODS: A total of 2,996 questionnaires were sent out to the heads of German anaesthesia departments and private anaesthesia practices. The questions covered frequency of muscle relaxants used,how they were used, and neuromuscular monitoring. Influences on the way muscle relaxants were used could be derived from the desire for specific properties of a muscle relaxant, the desire for different monitoring conditions and from the size of the institution. We correlated these features with application practice using logistic regression analyses. RESULTS: Of the 2,996 questionnaires 2,058 could be analysed (68.6%). Amongst those were 102 level one hospitals (5%) and 903 private practices (44%). The replies from 350 (17%) departments were based on surveyed data, 1,613 (78.5%) were based on estimations. The desire for certain properties of muscle relaxants correlated with the use in practice, as were the desire for a non-depolarizing replacement for succinylcholine, the size of the department and the frequency of use of neuromuscular monitoring. Over 50% of all German anaesthesia departments limited the use of muscle relaxants to three. The use of laryngeal masks reduced the use of muscle relaxants. CONCLUSIONS: The survey regarding use of muscle relaxants in Germany could for the first time give an overview on the use of anaesthesia-specific substances in Germany. From the different frequencies of use and use modalities,conclusions could be drawn towards a standard of application for the year 2000. Changes in this standard would raise the need for further trend surveys. The methods of statistical analysis and survey evaluation can be used as a base for further surveys.

Anesthesia↗
PubMed1995

Changes in acetylcholine receptor number in muscle from critically ill patients receiving muscle relaxants: an investigation of the molecular mechanism of prolonged paralysis.

OBJECTIVE: Previous reports have described prolonged paralysis after the administration of muscle relaxants in critically ill patients. The purpose of this study was to examine possible pathophysiologic causes for this paralysis by measuring muscle-type, nicotinic acetylcholine receptor number in necropsy muscle specimens from patients who had received muscle relaxants to facilitate mechanical ventilation before death. DESIGN: Prospective laboratory study of human muscle collected at autopsy. SETTING: Medical and surgical intensive care units (ICUs) at a university hospital and a research laboratory. PATIENTS: Fourteen critically ill patients, with a variety of diagnoses, all of whom required mechanical ventilatory support before their deaths in the ICU and who underwent post mortem examination. Patients were arbitrarily divided into three groups, according to their total vecuronium dose and number of days mechanically ventilated before death. Three patients were in the control group (defined as dying within 72 hrs of initiation of ventilatory support and receiving a total dose of < 5 mg of vecuronium). Six patients were in the low-dose group (defined as requiring ventilatory support for > 3 days before death and receiving a total vecuronium dose of < or = 200 mg). Five patients were in the high-dose group (defined as requiring ventilatory support for > 3 days before death and receiving a total vecuronium dose of > 200 mg). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Nicotinic acetylcholine receptor numbers as measured by specific 125I-alpha-bungarotoxin binding to human rectus abdominis muscle obtained at autopsy were determined. In general, receptor number reflected the clinical requirements for the muscle relaxants of each patient. Patients who had increasing requirements for muscle relaxants before death had increases in receptor number, as compared with control values. CONCLUSIONS: The increase in nicotinic acetylcholine receptor number in muscle from patients with an increasing requirement for muscle relaxants before death suggests that nicotinic acetylcholine receptor up-regulation may underlie the increased requirements for muscle relaxants seen in some patients. Furthermore, these findings suggest that muscle relaxant-induced, denervation-like changes may at least be partially responsible for prolonged muscle paralysis after the long-term administration of muscle relaxants. This study may provide the first information into the molecular mechanisms underlying prolonged paralysis.

Adult↗
PubMed1999

The pulmonary first-pass uptake of five nondepolarizing muscle relaxants in the pig.

BACKGROUND: It is not known whether the lungs influence the early pharmacokinetics of muscle relaxants and, if they do, whether differences in pulmonary uptake contribute to the differences in potency and/or onset time among muscle relaxants. Because the lungs are uniquely positioned, receive the entire cardiac output, have a large capillary surface area, and can temporarily store various basic drugs, the authors determined whether substantial pulmonary first-pass uptake of muscle relaxants occurs. METHODS: In 14 pigs, rocuronium, vecuronium, Org 9487, Org 7617, or d-tubocurarine were administered simultaneously with indocyanin green within 1 s into the right ventricle, and then arterial blood was sampled every 1.2 s (in the first min). The tibialis muscle response was registered mechanomyographically. RESULTS: The maximum block was 93% (68-100% [median and range]). Onset times ranged from 83 s (78-86 s) for rocuronium to 182 s (172-192 s) for d-tubocurarine. Fraction-versus-time outflow curves showed that the peak of muscle relaxants and indocyanin green occurred almost simultaneously. Pulmonary first-pass retention was negligible. The retention of muscle relaxants at 95% passage of indocyanin green was -9% (-31 to 18%). The difference in the mean transit time between muscle relaxant and indocyanin green was 1.0 (0.8 to 1.4), 0.2 (-0.8 to 0.3), 0.3 (0.2 to 0.4), 0.5 (0.2 to 1.3), and -2.2 s for rocuronium, vecuronium, Org 9487, Org 7617, and d-tubocurarine, respectively. CONCLUSIONS: There is no substantial pulmonary first-pass uptake of rocuronium, vecuronium, Org 9487, Org 7617, or d-tubocurarine in pigs. Therefore, differences in pulmonary first-pass uptake do not contribute to the differences in potency and/or onset time among muscle relaxants.

Androstanols↗
PubMed1983

Predictive value of muscle relaxant models in rats and cats.

A number of clinically effective muscle relaxants and structurally related compounds were examined in three animal models of muscle relaxant activity in order to determine the utility of these models in predicting clinical activity. The methods used were attenuation of morphine-induced rigidity in rats, decerebrate rigidity in cats, and the polysynaptic linguomandibular reflex in cats. Specificity of the compounds was assessed by comparing these data to the ability of the compounds to induce rotarod failure in rats and to inhibit the monosynaptic patellar reflex in cats. Diazepam and chlordiazepoxide were of limited potency in morphine-induced rigidity and decerebrate rigidity, but were potent on the polysynaptic reflex. Mephenesin, cyclobenzaprine, and the newer benzodiazepine, midazolam, were effective and moderately specific in all three models. Baclofen and dantrolene were effective but were of little or no specificity in all models. Analysis of the data yielded poor correlation between clinical muscle relaxant potency and the potencies obtained in these animal models. The correlation coefficients of 0.54, 0.50, and 0.70 for the linguomandibular reflex, decerebrate rigidity, and morphine rigidity, respectively, were not statistically significant, in contrast with a coefficient of 1.0 using previously reported data on these compounds in inhibiting morphine-induced Straub tail in mice. Thus, the three models used in this study may possess utility in the study of sites and mechanisms of action and structure-activity relationships of potential muscle relaxants, but they do not appear to be as useful as morphine-induced Straub tail in potency comparisons between different chemical classes.

Amitriptyline↗
PubMed1981

[General pharmacology of 6-amino-2-fluoromethyl-3-(o-tolyl)-4(3H)-quinazolinone (afloqualone), a new centrally acting muscle relaxant. I. Effects on the central nervous system (author's transl)].

The general pharmacology of afloqualone, a new centrally acting muscle relaxant, in the CNS was examined in mice and rats and findings compared with those of other central muscle relaxants. Afloqualone showed relatively strong hexobarbital and barbital anesthesia potentiating action. Taking into account the dose ratio of anesthesia potentiating action to the muscle relaxing action, however, the potency of anesthesia potentiating action of afloqualone is lower than that of chlormezanone. At doses producing muscle relaxing action, afloqualone inhibited spontaneous motor activity, methamphetamine-induced hypermotility, pentylenetetrazol-, nicotine-, and maximum electroshock-convulsions, fighting episodes in foot-shocked mice, conditioned avoidance response in rat pole-climbing test, and acetic acid-induced writhing syndrome and lowered normal body temperature. The dose ratios of these pharmacological actions to muscle relaxing action of afloqualone, however, were larger than those of chlormezanone and mephenesin. This suggests that the central depressant activity of afloqualone is less potent and the specificity of muscle relaxing action of afloqualone is higher than those of climbing behaviour, physostigmine-induced death, serotonin-induced heat twitch, and reserpine-induced hypothermia, even at 50 mg/kg. Tolperisone showed neither muscle relaxing action nor other central actions when administered orally.

Agonistic Behavior↗
PubMed1993

Muscle relaxant action of dantrolene sodium in rats.

The relationship between the muscle relaxant action and intramuscular concentration of unchanged dantrolene sodium [1-[5-(p-natrophenyl) furfurylidene amino] hydantoin sodium hemiheptahydrate, dantrolene] by intravenous administration of dantrolene was examined in rats. The mechanism of the muscle relaxant action of dantrolene was also examined. Dantrolene, unlike tolperisone, a centrally acting muscle relaxant, dose-dependently inhibited twitch contraction evoked by electrical stimulation of both the muscle and the phrenic nerve in the rat isolated phrenic nerve-diaphragm preparation to a similar extent (IC50: 9.5 and 6.5 x 10(-6) M, respectively). Inhibition of both twitch contractions by dantrolene (50 microM) was antagonized by 4-aminopyridine (42.5 microM) and caffeine (4 mM). The twitch contraction of the gastrocnemius muscle elicited by sciatic nerve stimulation was inhibited by intravenous administration of dantrolene in a dose-dependent manner. The effective intramuscular concentration of dantrolene producing 50% depression (ID50) was 3.4 micrograms/g tissue, equal to about 1 x 10(-5) M. We thus found a close relationship between IC50 in vitro and ID50 in situ. Furthermore, this study raised the possibility that dantrolene produces its muscle relaxant action by affecting peripheral muscular Ca2+ mobilization.

4-Aminopyridine↗
PubMed1987

[The value of prick tests in the detection of anaphylaxis caused by muscle relaxants].

Intradermal tests (IDR) are a sure diagnostic procedure for confirming the IgE origin of anaphylactoid accidents due to muscle relaxant drugs. Because carrying these out and interpreting them correctly is difficult, epidermal prick-tests (PT) could be used if they proved as sure as IDR. To ascertain this, IDR and PT were carried out in 38 patients who had a shock after being given a muscle relaxant 6 months to 5 years previously; for these tests, increasing concentrations of five muscle relaxants were used (suxamethonium, gallamine, alcuronium, pancuronium and vecuronium). The PT were also carried out with the five same pure and diluted muscle relaxants in a group of 147 volunteer controls. For the 38 patients, PT and IDR were always positive for the same drugs, but at different concentrations, the epiderm seeming less sensitive than the derm (with a ratio of 1 to 100). In the control group, all the tests were negative, even with the pure drug. PT with muscle relaxants were sensitive, specific of anaphylaxis, and permanent. Easy to carry out, easily interpreted, they could be useful as tests for predicting latent sensitisation in risk patients requiring muscle relaxants. But all muscle relaxants must be tested, and not just the one the anaesthetist is likely to use.

Adolescent↗
PubMed1993

Speed of action of various muscle relaxants at the neuromuscular junction binding vs. buffering hypothesis.

The speed of action of several nondepolarizing muscle relaxants (gallamine, rocuronium, D-tubocurarine, atracurium, vecuronium, pancuronium and doxacurium) was tested iontophoretically at the frog cutaneous pectoris neuromuscular junction at various temperatures. If differences in rate of onset and offset are due to different molecular rates of binding (and unbinding), and of resulting conformational changes, they should be strongly temperature dependent. In contrast, if differences are due to differences in buffered diffusion, temperature dependence should be low to moderate. The onset and recovery time constants of inhibition of brief acetylcholine pulses, caused by long pulses of relaxants for all of the muscle relaxants, were inversely related to apparent dissociation constants (KD values), that ranged from 4.56 microM (gallamine) to 0.11 microM (doxacurium). The kinetics showed only modest temperature dependence (Q10 values of 1/time constant of offset were typically < 1.4). Because KD values of all muscle relaxants were even less temperature dependent (Q10 < 1.3), this suggests that the kinetics of inhibition is probably determined by the extent of buffering in the synaptic cleft, and not by binding and unbinding. Diffusion of relaxants from the synaptic cleft is expected to be strongly buffered, because the nerve terminal presents a physical barrier to diffusion, and because of extremely high density of acetylcholine receptors. The density of acetylcholine receptors can be calculated from the time constant of offset and KD values of various relaxants, assuming that buffer diffusion is determining the kinetics of action of muscle relaxants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Milrinone, a phosphodiesterase III inhibitor, antagonizes the neuromuscular blocking effect of a non-depolarizing muscle relaxant in vitro.

Phosphodiesterase (PDE) inhibitors are occasionally used in patients receiving non-depolarizing muscle relaxants during anesthesia and intensive care. However, little is known about the influence of PDE III inhibitors on the effects of non-depolarizing muscle relaxants. The aim of this study was to elucidate the effects of milrinone, a PDE III inhibitor, on d-tubocurarine (dTc)-induced muscle relaxation in vitro and then to compare its effects with those of other activators of the adenylate cyclase (AC) system (aminophylline, a non-selective PDE inhibitor; forskolin, a direct AC activator; and isoproterenol, a beta-adrenoceptor agonist). Isometric twitch tensions of rat nerve-hemidiaphragm preparations elicited by indirect or direct stimulation (0.1 Hz) were measured. Indirectly elicited twitch tension partially depressed by dTc (1 microM) was antagonized by milrinone, aminophylline, and forskolin but was attenuated by isoproterenol. Directly elicited twitch tension was increased by aminophylline, forskolin, and isoproterenol but was not altered by milrinone. The results indicate that milrinone antagonizes dTc-induced muscle relaxation by recovering the neuromuscular transmission. It is noteworthy that PDE inhibitors and a beta-adrenergic agonist affect non-depolarizing muscle relaxation in opposite direction.

Adrenergic beta-Agonists↗
PubMed1989

[The effect of muscle relaxation training on patients with insomnia complaints].

This study was performed to examine the effect of muscle relaxation training on patients with insomnia complaints. The subjects were selected those who have taken poor sleep below 240-300 minutes per day, between 16-15 ages, without organic brain syndromes. Using the Budzinski's muscle relaxation training tapes the patients have been gotten the muscle relaxation training daily during four weeks and examined the state anxiety with Spielberger's Trait-State Anxiety Scale, and investigated Sleep amounts, Blood pressure, Pulse rates, Respiratory rates before and after the muscle relaxation training. The results were as follow: 1. The mean of the State anxiety after the muscle relaxation training (41.8 +/- 6.4) was significantly lower than that of before training (54.2 +/- 7.0) (p less than 0.001). 2. The mean of systolic blood pressure after the training (114.3 +/- 7.8 mmHg) was significantly lower than that of before training (139.0 +/- 9.8) (p less than 0.001). 3. The mean of Pulse rate after the training (89.2 +/- 3.0) was significantly lower than that of before training (103.9 +/- 7.4) (p less than 0.001). 4. The mean of Respiratory rate after the training (18.6 +/- 1.0) was significantly lower than that of before training (22.8 +/- 1.3) (p less than 0.001). 5. The mean of Sleep amount after the muscle relaxation training (459.8 +/- 52.4 minutes) was significantly increased than that of before training (287.3 +/- 30.3) (p less than 0.001).

Anxiety↗
PubMed1984

From activity to rest: gating of excitatory autogenetic afferences from the relaxing muscle in man.

The changes in reflex excitability of the motoneurones to the soleus (Sol) muscle occurring during and after voluntary releases of various duration from a constant plantar-torque level in isometric or isotonic conditions have been investigated in normal humans by means of the H-reflex and T-response. The amplitude of both reflexes during the release phase attains values lower than control (obtained in resting conditions) even in the presence of force and EMG activity; the maximal inhibition is reached at the end of the release; the reflexes recover gradually to control values over several seconds. The more abrupt is the release, the more inhibited is the reflex and the shorter is the time to recovery and vv. These results apply both in isometric and isotonic conditions. Activation of the antagonist muscles, sometimes occurring at the end of the fastest release, does not contribute to the H-reflex inhibition. Tonic isometric contractions and relative releases have also been evoked by the tonic vibration reflex (TVR). The H-reflex during the TVR-induced contractions were lower than control values, at variance with those obtained during the voluntary contractions, but their amplitudes during the releases had similar values and time-courses in both conditions, pointing to a common involved inhibitory mechanism. Any voluntary ballistic or ramp contraction taking place after a preceding release, in the period in which the H-reflexes were still inhibited, was not apparently influenced, despite the fact that H-reflexes evoked during the release-conditioned ramp contractions were significantly lower than when evoked during control ramps of similar characteristics. The results are discussed in terms of a premotoneuronal, possibly presynaptic, inhibitory mechanism.

Adult↗
PubMed1995

Absence of mechanical evidence for attached weakly binding cross-bridges in frog relaxed muscle fibres.

1. Passive force responses to ramp stretches at various velocities were measured in intact and skinned single muscle fibres isolated from the lumbricalis muscle of the frog. Force was measured using a fast capacitance transducer and sarcomere length was measured using a laser light diffraction technique at a point very close to the fixed end so as to avoid effects of fibre inertia. Experiments were performed at 15 degrees C with sarcomere length between 2.13 and 3.27 microns under high (170 mM) and low (20 mM) ionic strength. 2. The analysis shows that the force response is the sum of at least three components: (i) elastic (force proportional to the amount of stretch), (ii) viscous (force proportional to rate of stretch), and (iii) viscoelastic (resembling the response of a pure viscous element in series with an elastic element). 3. The amplitude of all these components increased progressively with sarcomere length in the whole range measured. 4. A further component, attributable to the short-range elasticity (SREC), was present in the force response of the intact fibres. 5. The amplitude of the force response decreased substantially upon skinning at high ionic strength but increased again at low ionic strength. The SREC was completely abolished by skinning. 6. None of the components of the force response was found to have the properties expected from the previously postulated 'weakly binding bridges'.

Animals↗
PubMed1989

Physiologic analysis of central motor pathways--simultaneous recording from multiple relaxed muscles.

The central motor pathways were studied with the technique of percutaneous electrical stimulation of the central nervous system in 40 normal volunteers. There were no significant differences between the right and left sides, or between males and females. A linear correlation between the cortical latency (Lcor) or the spinal latency (Lsp) and body height was observed, however, there was no correlation between the central conduction time (CCT) (Lcor-Lsp) and body height. Consequently, the CCT appears to provide a reliable estimate of the function of central motor pathways. We have established normal values for eight muscles at rest that would be required for localizing a very small intraspinal lesion.

Adult↗