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At least 433 records · Page 24Linked to original sources
PubMed1975

The use of a digital computer for the on-line real-time assessment of neuromuscular blockade in anaesthetized man.

A computer program written mainly in a high level language (ALGOL), but with the sampling routine and certain calculations written in assembly language (SIR), has been developed to assess neuromuscular blockade in anaesthetized man by means of an Elliott 903 digital computer. The program allows the on-line real-time analysis of a range of variables including twitch height, maximum slope of twitch and twitch pulse widths, peak height of tetanic contraction, end-height of tetanic contraction, the tetanic tension ratio and the percentage tetanic transmission. The program has been used to investigate the pattern of action of neuromuscular blocking drugs and has particular value in the study of the pharmacokinetic action of these drugs.

Computers↗
PubMed1988

Comparison of large dose of vecuronium with pancuronium for prolonged neuromuscular blockade.

Dose-duration relationships for vecuronium were determined and the duration of action produced by vecuronium 0.3 mg kg-1 shown to equal that of pancuronium 0.1 mg kg-1. Using these doses, the neuromuscular blocking properties and cardiovascular effects of the two drugs were compared. With large dose administration of vecuronium (0.3 mg kg-1), both the onset time (mean 81 s) and the 25-75% recovery index (mean 13.9 min) were about one-half those associated with pancuronium (mean 168.5 s and 29.3 min, respectively). The duration of action until 25% recovery was similar with both drugs. There was no evidence of cardiovascular instability with the large dose of vecuronium. Heart rate, however, was significantly slower (range 89.7-94.2% of control) 2-20 min after the injection of vecuronium. Vecuronium 0.3 mg kg-1 may have more favourable neuromuscular blocking effects than pancuronium 0.1 mg kg-1 and may be preferable to pancuronium when prolonged neuromuscular blockade is required.

Adolescent↗
PubMedDate not supplied

Reversal of neuromuscular blockade by glycopyrrolate and neostigmine. A study of the effects on lower oesophageal sphincter tone.

The effect of intravenous glycopyrrolate and neostigmine, a drug combination routinely given to antagonize non-depolarising neuromuscular blockade, on lower oesophageal sphincter tone was studied in twenty patients undergoing Caesarean section. Glycopyrrolate 0.6 mg and neostigmine 2.5 mg i.v. increased LOS pressure insignificantly by a mean of 0.2 kPa (P less than 0.1). In contrast, glycopyrrolate 0.6 mg and neostigmine 5 mg increased LOS pressure by a mean of 1.2 kPa (P less than 0.001). The latter dosage of this drug combination thus appears preferable in patients presenting for emergency surgery, if the integrity of the lower oesophageal sphincter is to be maintained during extubation and recovery from general anaesthesia.

Anesthesia, Obstetrical↗
PubMedDate not supplied

Neuromuscular blockade: the effects on two hippocampal RSA (theta) systems and neocortical desynchronization.

Neocortical and hippocampal electroencephalographic (EEG) activity were recorded from rats during: (a) spontaneous activities, (b) paralysis produced by curare or gallamine neuromuscular blockade, and (c) urethane anesthesia. All of the patterns of EEG recorded from normal rats were obtained from paralyzed rats including: (a) atropine resistant neocortical desynchronization and fast (6--12 Hz) hippocampal rhythmical slow activity (RSA) normally associated with overt Type I or voluntary movement, (b) atropine sensitive and urethane resistant slow (4--6 Hz) RSA which can be recorded from immobile animals during conditioning procedures, or during brain or sensory stimulation, and (c) large amplitude irregular neocortical and hippocampal EEG which can be recorded from immobile or sleeping animals. Depth profiles of RSA were taken from the hippocampal formation of urethanized and curarized rats during posterior hypthalamic stimulation. The results confirmed findngs of two RSA amplitude maxima with an approximate 180 degree phase difference, one location in stratum oriens of area CA-1, the other in stratum moleculare of the dentate gyrus, and suggest there are two generators of RSA. Atropine sensitive and atropine resistant types of RSA were found in each generator. The results suggest that RSA may be supported by both cholinergic and noncholinergic input to each generator and that neither RSA type could be only the result of proprioceptive feedback from joints or muscles.

Animals↗
PubMed1980

Clinical characteristics of long-term succinylcholine neuromuscular blockade during balanced anesthesia.

Thumb adductor twitch response to train-of-four (2 Hz for 2 seconds) stimulation of the ulnar nerve was used to assess the clinical characteristics of long-term neuromuscular blockade induced with continuous infusion of succinylcholine during balanced (N2O-O2-narcotic-thiopental) anesthesia. Twitch depression of 80 to 90% was maintained for 86 to 365 minutes by continuous infusion of succinylcholine at 86 +/- 5(SEM) micrograms/kg/min. Of 32 patients, 24 developed phase II block, defined as a train-of-four ratio of less than 50%. There was a large degree of individual variability in sensitivity to development of phase II block. This precluded defining a narrow dose range where transition from phase I to phase II occurred. Tachyphylaxis occurred in 25% of patients and was independent of the type of block. Neither dose nor duration of infusion was predictive of spontaneous recovery rate from phase II block. Of 24 patients who developed phase II block, 50% recovered spontaneously at a rate comparable to the recovery rate from a phase I block. The other 50% manifested prolonged recovery of neuromuscular function. After observing spontaneous recovery in these patients for 31 +/- 5(SEM) minutes, successful antagonism of residual phase II block with anticholinesterase agents was achieved.

Adult↗
PubMed1993

Dose-response relationships for edrophonium and neostigmine antagonism of rocuronium bromide (ORG 9426)-induced neuromuscular blockade.

BACKGROUND: Rocuronium bromide (ORG 9426) is a new nondepolarizing muscle relaxant with a rapid onset but an intermediate duration of action. The dose-response relationships for neostigmine and edrophonium were studied during antagonism of neuromuscular block induced by rocuronium bromide. METHODS: Sixty-four ASA physical status 1 or 2 adults were given 0.6 mg/kg rocuronium bromide during thiopental-fentanyl-nitrous oxide-isoflurane anesthesia. Train-of-four (TOF) stimulation was applied to the ulnar nerve every 10 s, and the force of contraction of the adductor pollicis muscle was recorded. When spontaneous recovery of first twitch height reached 10% of its initial control value, edrophonium (0.1, 0.2, 0.4, or 1 mg/kg) or neostigmine (0.005, 0.01, 0.02, or 0.05 mg/kg) was administered by random allocation. Neuromuscular function in another eight subjects was allowed to recover spontaneously. Assisted recovery was defined as actual recovery minus mean spontaneous recovery in patients who were not given antagonists. RESULTS: The dose-response curves for neostigmine- and edrophonium-assisted antagonism of rocuronium bromide neuromuscular blockade for the single twitch and TOF ratio were not parallel. The doses of neostigmine required to achieve 50% and 80% recovery (ED50 and ED80, respectively) of the first twitch after 10 min were 0.017 (0.001) and 0.033 (0.001) mg/kg (mean (standard error of estimate for the mean)), respectively. Corresponding ED50 and ED80 values for edrophonium were 0.161 (0.001) and 0.690 (0.001) mg/kg, respectively. These values corresponded to neostigmine:edrophonium potency ratios of 9.5 (0.56) and 21 (0.67) for first twitch ED50 and ED80 height, respectively. The calculated doses producing ED50 of the TOF ratio at 10 min were 0.017 (0.001) and 0.469 (0.001) mg/kg for neostigmine and edrophonium, respectively. These values corresponded to a potency ratio of 27.5 (1.66). CONCLUSIONS: Under the conditions described in this study, if reversal was attempted at 10% first twitch recovery, edrophonium was less capable than neostigmine of reversing fade (potency ratio of 19.2 and 27.5 at 5 and 10 min, respectively) than first twitch (potency ratio of 6.7 and 9.5 at 5 and 10 min, respectively) during antagonism of rocuronium bromide-induced blockade. Edrophonium was found to be less effective than neostigmine at reversing rocuronium bromide-induced TOF fade.

Adult↗
PubMed1991

Electromyographic assessment of the neuromuscular blockade produced in vivo by anatoxin-a in the rat.

The indirectly evoked compound action potentials (ECAP) of the plantar muscles of the rat were used to investigate the pharmacodynamics in vivo of the neuromuscular blockade produced by anatoxin-a. Onset time to maximum depression and the magnitude of maximum depression in amplitude of the ECAP were dose-dependent. The mean maximum percent depression (+/- S.D.) of the ECAP induced by single, supramaximal stimulations of the posterior tibial nerve after i.v. doses of (+)anatoxin-a hydrochloride at 0, 50, 100, 200 and 800 micrograms/kg were 3 (4), 53 (15), 82 (7), 95 (2), and 100 (1), respectively. The ED50 (95% confidence limits) for depression of the ECAP was 47 mg/kg (39-57 micrograms/kg). Rats administered 200 micrograms/kg or less of (+)anatoxin-a hydrochloride had 75% return of the pretoxin amplitude of the ECAP within 93 min. Animals dosed at 800 micrograms/kg did not have return of neuromuscular function and died despite mechanical ventilation, suggesting a lethal mechanism(s) of action in addition to respiratory paralysis. Percent decrements (+/- S.D.) in the amplitude of the fourth ECAP following repetitive stimulation at 10 Hz were 6 (5), 13 (22), 46 (18) and 59 (8) from (+)anatoxin-a hydrochloride given i.v. at 0, 50, 100 and 200 micrograms/kg, respectively. The decrement observed following repetitive stimulation was attributed to a presynaptic site of action. No change in maximal motor nerve conduction velocity or latency of the ECAP was observed after i.v. administration of (+)anatoxin-a hydrochloride at 100 micrograms/kg. LD50 values (95% confidence limits) for anatoxin-a administered i.v. to mice were 386 micrograms/kg (365-408 micrograms/kg, for (+)anatoxin-a hydrochloride and 913 micrograms/kg (846-985 micrograms/kg) for racemic anatoxin-a hydrochloride. No deaths were observed in mice after i.p. administration of (-)anatoxin-a hydrochloride at doses up to 73 mg/kg.

Action Potentials↗
PubMed1978

Recovery from neuromuscular blockade. a comparison between old and young patients.

Thirteen young and thirteen elderly patients undergoing elective surgery were given an anaesthetic using tubocurarine as the sole muscle relaxant. Following reversal with neostigmine, the time taken to recover from neuromuscular blockade was measured. No significant difference was found between the two groups of patients.

Adolescent↗
PubMed1998

Studies on neuromuscular blockade by boldine in the mouse phrenic nerve-diaphragm.

The effects of boldine [(S)-2,9-dihydroxyl-1,10-dimethoxy-aporphine], a major alkaloid in the leaves and bark of Boldo (Peumus boldus Mol.), on neuromuscular transmission were studied using a muscle phrenic-nerve diaphragm preparation. Boldine at concentrations lower than 200 microM preferentially inhibited, after an initial period of twitch augmentation, the nerve-evoked twitches of the mouse diaphragm and left the muscle-evoked twitches unaffected. The twitch inhibition could be restored by neostigmine or washout with Krebs solution. The twitches evoked indirectly and directly were both augmented initially, suggesting that the twitch augmentation induced by boldine was myogenic. Boldine inhibited the acetylcholine-induced contraction of denervated diaphragm dose-dependently with an IC50 value of 13.5 microM. At 50 microM, boldine specifically inhibited the amplitude of the miniature end plate potential. In addition, boldine was similar to d-tubocurarine in its action to reverse the neuromuscular blocking action of alpha-bungarotoxin. These results showed that the neuromuscular blockade by boldine on isolated mouse phrenic-nerve diaphragm might be due to its direct interaction with the postsynaptic nicotinic acetylcholine receptor.

Acetylcholine↗
PubMed2002

Novel piperidinium and pyridinium agents as water-soluble acetylcholinesterase inhibitors for the reversal of neuromuscular blockade.

A series of piperidinium and pyridinium agents containing a common structural fragment of 5,6-dimethoxybenzothiophene have been synthesised as water-soluble acetylcholinesterase inhibitors. Several compounds, for example 42 (AChE IC(50) 0.03 microM) have been found to reverse the neuromuscular blockade induced by vecuronium bromide in vitro and in vivo. Coupled with their high water solubility (up to 30-60 mg/mL), these compounds are potentially useful as intravenous reversal agents of neuromuscular blocking agents in surgical anaesthesia.

Acetylcholinesterase↗
PubMed1986

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.

Adult↗
PubMed1988

Antagonism of neuromuscular blockade. The cardiovascular effects in children of the combination of edrophonium and glycopyrronium.

Glycopyrronium 5 or 10 micrograms/kg was administered either simultaneously with, or 1 minute before, edrophonium 1 mg/kg in order to antagonise competitive neuromuscular blockade in 80 children. Both doses of glycopyrronium given before the edrophonium resulted in an initial significant (p less than 0.01) increase in heart rate. Heart rate decreased significantly (p less than 0.01) in all groups after the edrophonium was given, and only glycopyrronium 10 micrograms/kg administered before edrophonium prevented a substantial decrease below baseline. Initial heart rate responses to glycopyrronium or edrophonium are rapid, and measurements at intervals of 30 seconds may be necessary to record these changes.

Child↗