Morphological changes in long bone development in fetal akinesia deformation sequence: an experimental study in curarized rat fetuses

In order to investigate the transverse growth of the long bones during intrauterine development in the fetal akinesia deformation sequence (FADS), we studied curarized rat fetuses. Curarization was performed by daily subcutaneous administration of D-Tubocurarine from day 17 of gestation until term. Experimental fetuses were compared with a sham-operated control group. The total area and perimeter, the absolute and relative amount of periosteum and bone trabeculae, the major and minor axes, and the elongation factor were measured from histological cross-sections of the femoral metaphysis and diaphysis using an IBAS 1 image analysis system. Curarized rat fetuses showed growth retardation, a short umbilical cord, and multiple articular contractures, a phenotype consistent with FADS. Alterations in femoral shape and transverse growth that affected the diaphysis were noted in these fetuses. These included a decrease of total cross-section area and reduction of the absolute and relative amounts of bone trabeculae with marked thinning of the periosteum. Femoral cross-sections was rounder than controls. These results evidenced an impairment of the membraneous (periosteal) ossification of long bones produced by immobilization and/or decrease of muscular strength, and support our previous clinical findings of bone hypoplasia and osteopenia in FADS.

Gastroesophageal reflux during anesthetic induction with thiopental and succinylcholine

The effects of patient physiology and the prior administration of a nondepolarizing muscle relaxant on the frequency of gastroesophageal reflux during induction with thiopental sodium and succinylcholine were investigated. Forty patients underwent anesthetic induction during continuous esophageal pH monitoring. Twenty patients had preoperative symptoms of gastroesophageal reflux, and 20 asymptomatic patients served as controls. Half the patients in each group received a small dose of nondepolarizing muscle relaxant prior to induction. Five patients (25%) with gastroesophageal reflux and none of the control patients showed significant decreases in esophageal pH during induction. Two of these patients received prior administration of a nondepolarizing drug. In all five patients, reflux occurred during laryngoscopy and intubation, suggesting the possibility that succinylcholine did not play a role in the generation of reflux. Preoperative gastroesophageal reflux symptomatology is associated with an increased frequency of reflux during induction, and the vulnerable period seems to occur after the achievement of neuromuscular blockade during laryngoscopy. Preinduction administration of a non-depolarizing muscle relaxant prior to succinylcholine use had no demonstrable effect on the frequency of reflux during induction, although the numbers studied were too small to be conclusive.

[The non-depolarizing myorelaxants in orotracheal intubation. A clinical comparison]

The present study was designed to compare the rapidity of onset of neuromuscular blockade after administration of 5 different neuromuscular relaxants (succinylcholine, d-tubocurarine, pancuronium, atracurium and vecuronium) in 75 patients, randomly allocated in 5 treatment groups. The facilitation for endotracheal intubation was evaluated using a clinical score. The for onset relaxation was shorter when using succinylcholine. Among non-depolarizing relaxants an adequate facilitation for endotracheal intubation was observed, two minutes after administration of atracurium and vecuronium, while endotracheal intubation was difficult when using d-tubocuranine and pancuronium.

Use of atracurium or vecuronium to prolong the action of tubocurarine

Forty patients received tubocurarine in a dose greater than ED90. When neuromuscular function had recovered to amplitude of the first contraction of the train-of-four equals 10% of control, a small increment of atracurium or vecuronium was administered, repeating the same increment at each subsequent recovery to 10%. The intensity and duration of the neuromuscular block following the first increment was always greater than that of subsequent increments. The duration and intensity of the block was progressively reduced with subsequent increments until the responses to further increments were unchanged. These final means at steady state were: group 1 (atracurium 1.1 mg) 6.4 (0.3) min; group 2 (atracurium 2.0 mg) 8.2 (0.9) min; group 3 (vecuronium 0.25 mg) 5.8 (0.4) min; group 4 (vecuronium 0.5 mg) 13.2 (0.4) min.

An evaluation of priming with vecuronium

Priming with vecuronium was evaluated in three groups of patients. Group 1 (n = 10) received tubocurarine 0.05 mg kg-1, group 2 (n = 19) received physiological saline and group 3 (n = 21) received vecuronium 0.012 mg kg-1. After 4 min maximum inspiratory pressure was measured. Anaesthesia was induced with thiopentone 6-8 mg kg-1 and controlled ventilation with nitrous oxide and oxygen via a face mask instituted. The ulnar nerve was stimulated at the wrist. At 5 min group 1 patients received suxamethonium 1.5 mg kg-1, group 2 received vecuronium 0.072 mg kg-1, and group 3 received vecuronium 0.060 mg kg-1. Intubation was accomplished at 6.5 min in all patients in group 1, 89% in group 2 and 90% in group 3. Patients in group 1 had no twitch response to stimulation at the time of intubation. Mean T4:T1 ratios at 6.5 min were 0.82 in group 2 and 0.61 in group 3 (P less than 0.05). Intubating conditions were excellent in all group 1 patients, and in 53% and 67% of groups 2 and 3, respectively. Two patients in group 3 did not tolerate the priming dose and many had subjective complaints. Four group 3 patients could not sustain head lift and five showed decreased inspiratory pressure. Priming did not improve intubating conditions when compared with a single bolus technique and was not well tolerated.

Comparison of atracurium and d-tubocurarine for prevention of succinylcholine myalgia

We compared the incidence of postoperative myalgia (POM) and fasciculations when atracurium (ATR) or d-tubocurarine (DTC) was given prior to succinylcholine (SDC) for tracheal intubation in 44 ASA class I or II outpatient females undergoing laparoscopy. The subjects were assigned to one of three groups: group 1 received 0.025 mg/kg ATR; group 2 received 0.05 mg/kg DTC; and group 3 received saline (NS), all in a double-blind manner. Thiopental was administered 1 min and 45 sec after pretreatment in doses adequate to allow control of ventilation. Three minutes after pretreatment, SDC 1.5 mg/kg was given, and fasciculations were recorded on a scale of 0-3. All patients were questioned 1 and 3 days postoperatively about POM, using a scale of 0-3. Fasciculations occurred in 79% of patients given saline, in 46% of those receiving ATR, and in 12% of those given DTC. Eighty-five percent of ATR patients were free of POM on postoperative day 1. The corresponding figures for DTC and NS were 59% and 43%, respectively. Only the difference between ATR and NS achieved statistical significance. On the third postoperative day, POM was rare and there were no significant differences among the groups. We conclude that DTC is a better defasciculant than ATR. DTC was, however, not significantly better than NS in the prevention of POM. The findings suggest that ATR may be the drug choice for the prevention of POM.

Acetylcholine receptor binding properties at the rat neuromuscular junction during aging

Specific binding characteristics of acetylcholine receptors at the diaphragm neuromuscular junction of rats aged 10 (mature adult) and 28 (aged) months were assayed by measuring 125I-alpha-bungarotoxin binding. Maximal binding to intact tissue samples was greater in the older rats; this could be attributed to an age-related increase in terminal branching. The toxin concentration at which half-maximal binding occurred increased in the older rats. Binding kinetics were assayed in finely minced tissue samples, and the association rate constant was observed to decrease in the 28-month animals. Retardation of the initial rate of toxin binding by d-tubocurarine (dTC) in minced tissue was described by a two-component nonlinear Hofstee plot; IC50 values (7.1-7.2 microM and 39.0-46.5 nM) were about the same for both age groups, but there was a significant shift toward the low-affinity values in the aged rats. Rhodamine-conjugated alpha-bungarotoxin was used to visualize receptor localization. There were no major changes in receptor distribution, and nerve terminals were consistently associated with receptors and vice versa. The data indicate a shift toward lower binding affinity during aging, which may involve changes either in one of the two toxin-binding sites on individual receptors, in dTC blocking of the channel moiety, or in receptor types.

[Spontaneous development of paralysis induced by equipotent doses of vecuronium, atracurium, fazadinium, pancuronium, gallamine and d-tubocurarine]

Thirty-six patients undergoing elective surgery were studied after obtaining their informed consent. They were randomly assigned to six series of six patients each. One hour before anaesthesia, all patients received 0.2 mg.kg-1 diazepam orally. After induction of anaesthesia with 1-1.5 mg.kg-1 methohexitone and 5 micrograms.kg-1 fentanyl, the patients were paralysed and ventilation was controlled manually (semi-open circuit; 50% N2O/50% O2). Each patient received a single dose of either 70 micrograms.kg-1 fazadinium, 70 micrograms.kg-1 pancuronium, 2,500 micrograms.kg-1 gallamine or 450 micrograms.kg-1 d-tubocurarine. Neuromuscular function was monitored by measuring the isometric contraction of the adductor pollicis muscle in response to supramaximal stimulations of the ulnar nerve at the wrist (square wave pulse of 0.2 ms duration at supramaximal intensity delivery at 0.1 Hz). Three parameters were measured: the time between the injection of the relaxant drug and recovery of the twitch height at 50% of its baseline (RT0-50); the time between the injection of the relaxant drug and recovery of the twitch height at 90% of its baseline (RT0-90); the time between the injection of the relaxant drug and recovery of the twitch height from 25 to 75% of its baseline (RT25-75). The values of the observed parameters were expressed in minutes (means +/- SEM).(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil as an adjuvant of balanced anaesthesia for tonsillectomy in adults

In a double-blind study, 80 adult patients, undergoing tonsillectomy, were randomly allocated to one of the four groups: d-tubocurarine (d-Tc) 50 micrograms/kg+alfentanil (Alf) 20 micrograms/kg, d-Tc 50 micrograms/kg+Alf 50 micrograms/kg, Alf 10 micrograms/kg+Alf 20 micrograms/kg, Alf 10 micrograms/kg+Alf 50 micrograms/kg. The first drug was given 2 min before thiopental and the second drug 1 min before inserting the mouth gag. Intubation was facilitated with suxamethonium. Anaesthesia was maintained with 70% nitrous oxide in oxygen and peripheral muscle relaxation during operation with vecuronium. For analysis of the induction characteristics, both d-Tc-pretreatment groups were treated together and compared with the results of the Alf-pretreatment groups. Muscle fasciculations occurred in 20% in the d-Tc group and in 70% in the Alf group. Neither d-tubocurarine nor alfentanil prevented the cardiovascular intubation response. Cardiovascular responses to the placement of the mouth gag occurred only in the lower-dose alfentanil groups. ECG changes during operation occurred in 25-45% of the patients. The most common ECG change was junctional rhythm. The operating conditions were good in 65-80% of the patients. The mean recovery score (0-10) ranged from 9.3 to 9.7 between the groups. The incidence of nausea ranged from 20-30% and that of vomiting from 10-25% between the groups. Bleeding from the operation site occurred in 20-30% of the patients. None of the patients needed sutures to stop the bleeding.

Potentiation of atracurium by pancuronium and d-tubocurarine

In 60 adult patients undergoing general surgical procedures, the effect of pancuronium or d-tubocurarine "pretreatment" on the injection of a 0.1 mg X kg-1 bolus of atracurium was measured in two separate studies. In study 1, the patients received either 0.5 mg (approximately 0.007 mg X kg-1) or 1.0 mg (approximately 0.015 mg X kg-1) pancuronium, or placebo (saline) three minutes before the injection of atracurium 0.1 mg X kg-1. In study 2, the patients received 0.05 mg X kg-1 or 0.1 mg X kg-1 d-tubocurarine, or a placebo. The degree of neuromuscular blockade was assessed by evoked mechanogram (adductor pollicis muscle) using supramaximal train-of-four stimulation. Patients receiving pancuronium or d-tubocurarine pretreatment (equal to an ED5-ED15 dose) showed significantly greater inhibition of twitch (ED70-ED80) and train-of-four ratio compared with the placebo groups (ED35-ED40). Pretreatment with the larger dose of d-tubocurarine (0.1 mg X kg-1) was associated with significant neuromuscular blockade. It is concluded that pancuronium and d-tubocurarine pretreatments potentiate the clinical action of 0.1 mg X kg-1 atracurium in man by 35-100 per cent.

Anaesthesia for Friedreich's ataxia. Case report and review of the literature

A patient with Friedreich's ataxia was anaesthetised on two occasions. The neuromuscular blocking agent was atracurium 0.5 mg/kg on the first occasion and tubocurarine 0.5 mg/kg on the second. The effect of each was monitored using the train-of-four twitch technique. Friedreich's ataxia has been reported to cause a marked sensitivity to non-depolarising muscle relaxants and hyperkalaemia, with resulting cardiac dysrhythmias after suxamethonium. This patient did not demonstrate an abnormal response to either relaxant; the operating conditions were satisfactory and recovery was not delayed. These drugs may be safely used in this condition provided that monitoring is adequate.

Prolonged neuromuscular blockade with atracurium

During general anaesthesia with oxygen, nitrous oxide and enflurane, a 29-year-old woman received a total of 105 mg (1.78 mg X k-1) of atracurium over a 2.5 hour period. The neuromuscular blockade could not be completely reversed with neostigmine and mechanical ventilatory support was necessary for three hours postoperatively. The patient received succinylcholine without unusual sequelae before and after this episode. This is the first report of a patient who exhibited prolonged weakness after receiving atracurium.

The incidence of EEG abnormalities and outcome of infants paralyzed with neuromuscular blocking agents

The EEGs of 40 infants paralyzed with D-tubocurarine or pancuronium during the neonatal period were reviewed retrospectively. The 23 infants who survived were re-examined at 1-3 yr of age. Sixteen infants had normal or mildly abnormal EEGs in the neonatal period; 3 died of nonneurologic causes; the remainder were normal at follow-up. Three of 8 infants with moderately abnormal EEGs in the neonatal period died, 2 had neurologic sequelae at follow-up, and 3 were normal at follow-up. Eleven of 16 infants with markedly abnormal EEGs died, and 5 had neurologic deficits at follow-up. Seizures occurred in 16 infants. Ten (63%) of the 16 died, whereas only 7 (29%) of 24 infants without seizures died (p less than .1). Eight infants had seizures only during paralysis. The EEG was statistically the best predictor of neurologic outcome when compared with the following variables recorded before paralysis: estimated gestational age (EGA), birth weight, Apgar score at 1 and 5 min, lowest PO2 and pH and highest PCO2. This study establishes the value of the EEG in the neurologic assessment of iatrogenically paralyzed newborns in the detection of seizures, and confirms previous studies which showed the value of EEG in predicting outcome.

Evoked responses in normal and diseased muscle with particular reference to twitch potentiation

The compound muscle action potential and isometric twitch tension evoked by single and repetitive electrical stimuli are indicators of the number of motor units activated and of the contractile properties of the muscle. The action potentials and mechanical responses were recorded in proximal and distal muscles in patients with myasthenia gravis and myopathy and compared with findings in normal subjects. In normal muscle, at low rates of stimulation (2-3 s-1) the decrement was at most 5% in the action potential and 15-24% in the twitch tension. Tetanic stimuli (50 s-1) were unsuitable for diagnostic purposes because of movement artefact. In patients with myasthenia gravis, the incidence and size of the decrement of evoked responses were greater in the platysma than in the elbow flexors and the adductor pollicis (ADP) muscles. The 2-3 times greater post-tetanic facilitation (PTF) of the action potential in the platysma than in extremity muscles also indicates a more severe functional block in facial muscle. The PTF is an indicator of recruitment of blocked fibres. The maximal decrement was grossly related to the titre of antibodies against the acetylcholine receptor. To reveal failure of neuromuscular transmission in patients with myasthenia gravis without a decrement, a small dose of d-tubocurarine (0.2 mg in 30 ml of saline) was injected i.v. in the upper arm in a regional curare test. The sensitivity was greater in patients with myasthenia gravis than in controls and in patients with myopathy. Potentiation of twitch tension reflects contractile properties. In normal muscle twitch potentiation in the staircase (1-3 s-1, 100 s in duration) and after tetanus (50 s-1, 1.5 s in duration) was 2-3 times greater in the platysma than in the elbow flexors and ADP, presumably related to the greater proportion of fast-twitch fibers in facial muscle. The amplitude of the action potential and the twitch tension varied proportionally with the number of fibers activated and the difference in the decrements of the action potential and the twitch during the staircase in some patients with myasthenia gravis showed that the staircase phenomenon was diminished suggesting abnormalities in the excitation-contraction coupling. The diminution of the staircase and post-tetanic potentiation (PTP) in myopathy also indicates impairment of the excitation-contraction coupling. In rats with severe chronic myasthenia gravis, the staircase and PTP were decreased even when the failing neuromuscular transmission was circumvented by applying direct stimuli to the extensor digitorum longus muscle (EDL).

[Interaction of acetylcholine and tubocurarine with protein molecules of the actin complex and phosphatidylcholine]

By means of surface Wilhelmi weight type changes of monomolecular layer properties of some proteins and lipids at the air--water boundary have been studied during acetylcholine and tubocurarine injection in the subphase. Active interaction of acetylcholine and tubocurarine molecules with monolayers of actin, myosin and phosphatidylcholine was observed, while the properties of human serum albumin (HSA) and cholesterine were not influenced by the same physiologically active substances. These substances had no effect on the area of monolayers and on other physico-chemical parameters of HSA and cholesterine. On the other hand when acetylcholine is present in the subphase of phosphatidylcholine monolayer the velocity of HSA penetration in these monolayers in sharply decreased.

Experimental study on the etiology of congenital multiple arthrogryposis

The effect of temporary immobility of the muscles in the embryo, induced by continuous infusion of d-tubocurarine into the ovum, was studied in 31 chick embryos. The ankle and foot joints showed flexion contractures with equal frequency, but the knees were less severely affected. Histological examination demonstrated peri-articular and intra-articular fibrosis, and fibrosis of the muscles of the limb. These experimental lesions closely resemble those of arthrogryposis. It is therefore suggested that the aetiology of human arthrogryposis may be based on a common pathogenetic mechanism; lack of joint movement during embryonic life.

Beneficial action of glucocorticoid treatment on neuromuscular transmission during early motor nerve degeneration

The effects of a short-term, high-dose glucocorticoid pretreatment regimen (triamcinolone diacetate, 8 mg/kg i.m. daily for 7 days) were examined on neuromuscular transmission deficits observed in the in vivo cat soleus nerve-muscle preparation at 48 hr after soleus nerve transection. The pretreated preparations had 20% more functional motor nerve terminals than the untreated. This was evidenced by a significantly (P less than 0.01) lesser difference in the indirectly evoked isometric contractile tensions between the denervated muscle and the contralateral intact preparation as a result of prior glucocorticoid treatment. The glucocorticoid pretreatment also significantly improved the capacity of the trophically deprived soleus motor nerve terminals to maintain transmission during high-frequency activation (100 to 400 Hz for 10 s). Moreover, triamcinolone treatment before nerve transection completely prevented the development of an increased sensitivity to d-tubocurarine neuromuscular block in untreated, 48-h nerve-transected preparations. These results demonstrate an ability of an intensive high-dose glucocorticoid treatment to sustain single and repetitive neuromuscular transmission during early anterograde nerve degeneration.

Cardiac effects of self-taming of succinylcholine and repeated succinylcholine administration

Pretreatment with small (10 mg) doses of succinylcholine ("self-taming") decreases the incidence of muscle fasciculations following succinylcholine administration and may decrease the incidence of other unwanted effects. This study was designed to assess the cardiac effects of such self-taming and to assess the degree of protection afforded against bradydysrhythmias following subsequent succinylcholine administration. Sixty patients were studied and allocated randomly to three groups of twenty. Each group was assigned a different form of pretreatment. Patients in group I received 10 mg of succinylcholine immediately after induction. Patients in group II were treated with d-tubocurarine 0.04k mg . kg-1 three minutes before induction. Patients in group III received no pretreatment. All patients were induced with thiopentone 4 mg . kg-1 followed by succinylcholine 1 mg . kg-1 45 seconds later. A second dose of succinylcholine 1 mg . kg-1 was administered to the patients in the two pretreatment groups between four and five minutes after the first dose of succinylcholine. Following both the first and second doses of succinylcholine patients in the self-taming group showed a significantly greater incidence of bradydysrhythmias when compared to the other two groups. It is concluded that the use of a self-taming technique is potentially hazardous, and that it does not confer protection against repeated succinylcholine administration.

The ionization of morphine, hydroxyamphetamine and (+)-tubocurarine chloride and a new method for calculating zwitterion constants

1 An improved method for estimating the zwitterion constants of phenolic amines is described which involves the exploratory least-squares fit of absorbance (at a suitable wavelength) to pH, starting with estimates of pK1 and pK2 obtained electrometrically. 2 With the method it is possible to see that hydroxyamphetamine (alpha-methyltyramine) has a higher zwitterion constant than tyramine and the zwitterion constants of both compounds are lower at 37 degree C than at 25 degree C. 3 The zwitterion constant of morphine is not reduced by raising the temperature from 25 degree to 37 degree C and the effect of temperature is much greater in compounds with a primary or secondary amino group than with those containing a tertiary amino group. Some zwitterions may be stabilized by hydration and their formation will be reduced by a rise in temperature which will break up water structure. 4 From electrometric titrations with (+)-tubocurarine chloride in 0.1 M NaCl estimates of pK1, pK2 and pK3 were 7.6, 8.65 and 9.65 at 25 degree C and 7.4, 8.6 and 9.7 at 37 degree C, compared with 7.8, 8.85 and 9.75 given by Perrin (1980). However, the effects of pH on absorbance show that the phenolic groups lose a proton before the ammonium group so there is extensive zwitterion formation which is probably greater at 25 degree than at 37 degree C. the p-phenolic group (position 13) probably ionizes first with the phenate form stabilized by hydration involving water molecules and the protonated form of the (1-) ammonium group.