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Biomedical subjects

R S Clarke

Publications and source records attributed to R S Clarke.

At least 55 records · Page 3Linked to original sources
PubMed1985

Histaminoid responses to atracurium, vecuronium and tubocurarine.

Sixty patients scheduled for elective surgery underwent intradermal testing with 0.1 ml of the following solutions diluted in 0.9% saline: vecuronium and tubocurarine (1 in 1,000), atracurium (1 in 1,000 and 1 in 10,000), thiopentone (1 in 100) and also a 0.9% saline control. Thirty minutes later, an area of erythema of greater than 1.5 cm, or a wheal exceeding 1.0 cm in diameter, was recorded as a positive reaction. The patients then randomly received equipotent doses of atracurium, vecuronium or tubocurarine during a standardized anaesthetic induction. Any cutaneous reaction and the percentage fall in systolic pressure three minutes after administration of the relaxant were recorded. In 51 patients plasma IgE levels were measured. The incidence of positive cutaneous reactions to intradermal and intravenous relaxants was significantly different with each agent (p less than 0.01). The percentage fall in systolic pressure after tubocurarine was significantly different relative to the other two agents (p less than 0.01). This was regarded as reflecting potency in releasing histamine and placed the relaxants in the same order: tubocurarine, atracurium and vecuronium. The response to intradermal administration was no guide to the subsequent response after intravenous administration of the three relaxants. IgE levels below 15 IU X ml-1 occurred significantly more often in females and were associated with a significantly higher incidence of cutaneous reactions after intradermal atracurium (1 in 1,000 and 1 in 10,000) (p less than 0.05 and 0.001 respectively) and tubocurarine (1 in 1,000). With these two agents, generalized flushing after intravenous administration was also more common in this group, relative to the normal/high IgE group.

Adult↗
PubMed1985

Comparison of cumulative and single bolus dose techniques for determining the potency of vecuronium.

The potency of vecuronium was determined using single bolus dose administrations of 10-50 micrograms kg-1 in 28 patients anaesthetized with thiopentone, nitrous oxide, oxygen and fentanyl. The results were compared with those previously obtained using a cumulative dose technique in a comparable group of 10 patients. The 50% and 95% blocking doses (ED50 and ED95) of vecuronium were found to be 23.1 and 39.6 micrograms kg-1, respectively. These were significantly lower than the 30.5 and 56.7 micrograms kg-1 obtained previously using the cumulative dose technique. We recommend the use of single bolus dose method of determining potency for relatively shorter-acting drugs like vecuronium.

Adult↗
PubMed1985

Allergy, plasma IgE level and anaphylactoid response: a hypothesis.

Any simple test predictive of immediate hypersensitivity-like (anaphylactoid) response to anaesthetic agents would be clinically useful. Possession of the traits of allergy or atopy, and of raised plasma IgE levels, all easily established, have previously been reported as predisposing factors. The usefulness of such observations has been limited by the fact that many reactions are not immune and do not involve IgE antibodies. This hypothesis suggests how IgE levels may be widely predictive of other reaction mechanisms and partially explains some of the divergent views on the mechanisms of anaphylactoid response which occur in the literature.

Adult↗
PubMed1985

Haemodynamic changes during induction of anaesthesia with midazolam and diazepam (Valium) in patients undergoing coronary artery bypass surgery.

Midazolam 0.3 mg/kg and diazepam 0.5 mg/kg were used for induction of anaesthesia in two groups of 10 patients each undergoing coronary artery bypass surgery. Haemodynamic variables were measured during induction of anaesthesia, after pancuronium and following tracheal intubation. Haemodynamic indices were derived from these measurements using standard formulae. The induction of anaesthesia with midazolam produced a slight but significant increase in heart rate. There was a significant fall in systemic arterial pressure and pulmonary artery pressure following both drugs. Despite the fall in systemic arterial pressure, the cardiac index was maintained in patients who received midazolam. The cardio-stimulatory effect of laryngoscopy and tracheal intubation was not prevented by either of the benzodiazepines and morphine in the dosage used. Midazolam is a suitable alternative to diazepam as part of an intravenous induction regimen in patients with ischaemic heart disease.

Anesthesia, Intravenous↗
PubMed1985

Atracurium in clinical anaesthesia: effect of dosage on onset, duration and conditions for tracheal intubation.

Conditions for tracheal intubation at 90 seconds, time to onset of maximum block and duration of clinical relaxation after five different doses of atracurium, which ranged from 0.4 to 1.0 mg/kg were studied in 200 adult patients who were anaesthetized with nitrous oxide, oxygen and halothane or fentanyl. The conditions for intubation improved significantly with increasing doses, and were acceptable in 55% patients with a 0.4 mg/kg dose and in about 90% of those who received the two higher doses. The time to onset of complete block was 257 seconds with 0.4 mg/kg and decreased progressively to 124 seconds with 1.0 mg/kg. The duration of clinical relaxation under fentanyl anaesthesia averaged 29 minutes with 0.4 mg/kg and increased in a dose-related manner to 57 minutes with 1.0 mg/kg: halothane anaesthesia produced only a marginal increase. There was no evidence of cumulation with up to six repeat doses of 0.125 mg/kg. The only side effect noticed was cutaneous flushing observed in 42% of patients. This was again dose dependent, being 18% with 0.4 mg/kg and increasing to 73% after 1.0 mg/kg. There was associated hypotension and bronchospasm in one patient.

Adolescent↗
PubMed1985

Vecuronium and atracurium in the elderly: a clinical comparison with pancuronium.

The intubating conditions, time to complete block and duration of clinical relaxation were observed in a group of 101 elderly patients (aged over 65 years) following pancuronium 0.1 mg kg-1, vecuronium 0.1 mg kg-1 or atracurium 0.5 mg kg-1. The intubating conditions in the three groups were similar when assessed at 2 min following relaxant administration. The time to complete block was shortest with vecuronium (4.3 min) in comparison to atracurium (5.0 min) and pancuronium (6.0 min), but the differences were not statistically significant. The duration of clinical relaxation, however, was significantly shorter with vecuronium (37 min) and atracurium (35 min) in comparison to pancuronium (99 min).

Aged↗
PubMed1984

Infusion rates for anaesthesia with propofol.

The infusion rate of propofol which would produce anaesthesia, when combined with nitrous oxide in oxygen, was studied in 75 fit unpremedicated patients undergoing body surface operations. The infusion rates were based on multiples of the median dose required to produce anaesthesia by intermittent injection in an additional 20 patients. The scatter of doses showed a right skew, for both intermittent and continuous use. This was corrected by loge transformation and derived data presented graphically.

Adolescent↗
PubMed1984

Dose-response studies with pancuronium, vecuronium and their combination.

Pancuronium, vecuronium and a combination of these were administered in an incremental fashion to study any potentiation of effect with the combination of the two relaxants. The ED95 (dose producing a 95% block) of the combination was 29 micrograms kg-1 for each component in comparison to 57 micrograms kg-1 for vecuronium and 59 micrograms kg-1 for pancuronium. The dose-response curves for the three groups did not differ from each other and no potentiation was demonstrated.

Adult↗
PubMed1983

New drugs--boon or bane? Premedication and intravenous induction agents.

Research on the benzodiazepines has shown that they have certain advantages over the opiates as premedicants. Diazepam, which produces good tranquilization, is well absorbed when given orally though absorption is influenced by other drugs given at the same time. Oral lorazepam leads to more prolonged sedation and amnesia but the final elimination is more rapid. Several new intravenous anaesthetics have been introduced during the last five years but none seems likely to replace thiopental. The theoretical disadvantages of thiopental are offset by its water-solubility, and the use of Cremophor EL in preparations of propanidid, alphaxalone, di-isopropyl phenol and one preparation of diazepam has led to many hypersensitivity reactions. Ketamine is gradually finding its rightful place in anaesthesia but its use is becoming limited to anaesthesia in difficult circumstances. The future concomitant use of other drugs and separation of isomers of ketamine may again broaden its applications. The new water-soluble steroid minaxolone has its own disadvantages, and the water-soluble benzodiazepine midazolam is as unpredictable for induction of anaesthesia as diazepam.

Alfaxalone Alfadolone Mixture↗
PubMed1983

Clinical evaluation of Org NC 45.

Org NC 45, a new non-depolarizing neuromuscular blocking drug, was evaluated in 200 adult patients. The drug was administered in doses of 0.1, 0.15 or 0.2 mg kg-1. Intubation could be satisfactorily carried out at around 90 s in 90% of patients. The duration of clinical relaxation varied from 23 min with 0.1 mg kg-1 and neuroleptanaesthesia to 71 min with 0.2 mg kg-1 and anaesthesia with halothane or enflurane. The duration of clinical relaxation following repeated administration of 2-3 mg was remarkably constant (between 17 and 20 min) thus showing lack of cumulation. The antagonism of residual block was prompt and easy following administration of neostigmine, and the drug lacked any significant cardiovascular effects as seen by routine monitoring.

Adult↗
PubMed1983

Pretreatment with vecuronium as a prophylactic against post-suxamethonium muscle pain. Comparison with other non-depolarizing neuromuscular blocking drugs.

One hundred and ninety-eight patients undergoing minor surgery were assessed for evidence of post-suxamethonium muscle pain on the 1st and 2nd days following surgery. Patients were allocated to nine groups and were given one of four non-depolarizing neuromuscular blocking drugs (vecuronium, gallamine, tubocurarine or pancuronium) 1 or 2 min before the administration of suxamethonium. A control group received an inert medication. Forty-one per cent of patients receiving no pretreatment experienced muscle pain. This frequency was decreased to around 20% following pretreatment. In general, the frequency of pain was less in the groups receiving pretreatment at 1 min, but the difference was not significant. The groups receiving vecuronium before suxamethonium had the lowest overall frequency of pain over the 2 days (19%), although this was not significantly different from other pretreatments.

Adolescent↗
PubMed1982

Epidemiology of adverse reactions in anaesthesia in the United Kingdom.

Adverse reactions to intravenous anaesthetics and muscle relaxants are characterised by peripheral vasodilatation with oedema, hypotension, tachycardia, bronchospasm and (more rarely) vomiting and abdominal cramps. The number of published cases in the U.K. is rising yearly. The frequency with all cremophor-containing drugs is about 1 in 1,000 cases but the number recorded following other induction agents is increasing. Most reactions following muscle relaxants have been documented in other countries but this probably reflects local interpretation rather than true geographical differences. The incidence could be reduced by avoiding the use of all cremophor-containing drugs and death from actual incidents could be prevented by having adequate resuscitation measures available.

Adjuvants, Anesthesia↗