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Biomedical subjects

N M Cass

Publications and source records attributed to N M Cass.

At least 19 recordsLinked to original sources
PubMed2004

Medicolegal claims against anaesthetists: a 20 year study.

A total of 222 medicolegal claims involving 160 anaesthetist members of Victoria's largest medical indemnity organization during the period 1980 to 1999 are reported, with 35% of anaesthetists having a claim. There were 49 claims in the first decade and 173 in the second, with 84 related to dental injury being predominant. Other common causes of claims were awareness, epidural anaesthesia, coronial enquiries, nerve palsies, postoperative complications and circulatory arrest. Anaesthetists were joined with surgeons in 17 claims. The average delay between the incident and the resolution of the claim was 11 months for dental claims and 46 months for non-dental ones.

Anesthesia↗
PubMed1990

Simultaneous monitoring of force, acceleration and electromyogram during computer-controlled infusion of atracurium in sheep.

Five sheep were anaesthetised with sodium thiopentone, nitrous oxide and oxygen, and the lungs ventilated artificially. A computer-controlled infusion of atracurium employing feedback from isometric force measurement was set to maintain 15, 50 and 85% depth of neuromuscular block. Each was held constant for 30 minutes, while isometric force and electromyogram were measured on the left forelimb and acceleration on the right. The acceleration transducer records at the three levels of block were practically identical with those from force measurements: mean differences (SD) between simultaneous measurements being 3.6 (5.4)%. EMG value was 10.1 (12.0)% different from force measurement. Correlation between simultaneous force and either acceleration or EMG was excellent (r = 0.986 and 0.938 respectively). In clinical practice all three techniques measure block comparably. In the sheep forelimb, EMG was a less reliable method of measuring block.

Animals↗
PubMed1986

Computer-controlled muscle paralysis with atracurium in the sheep.

Paralysis was maintained in sheep by computer-controlled infusion of atracurium, using the integrated electromyogram as a measure of neuromuscular transmission. A number of experiments were conducted to ascertain the average infusion rate required to achieve a given level of paralysis for one hour. Each experiment yielded a point on a plot of paralysis versus infusion rate. A dose-response curve based upon a simple model of drug receptor interaction at the neuromuscular junction was fitted to the experimental points by least squares and is able to provide a useful explanation of clinically observed behaviour. The recovery time was also measured in each experiment and plotted against both prior level of paralysis and prior average infusion rate.

Animals↗
PubMed1981

Electromyographic monitoring of neuromuscular block.

Neuromuscular blocking agents are widely used in anaesthesia, and a simple quantitative method of monitoring their effects is desirable. This paper describes a new instrument which has been developed for electromyographic monitoring of neuromuscular block by a non-invasive technique which is both reliable and easy to use. The median nerve is stimulated at the wrist and the electromyogram (e.m.g.) from a thenar muscle is detected, rectified and integrated electronically to produce a meter display of the assessment of block. The method is recommended for routine use.

Child↗
PubMed1980

Reversal of non-depolarizing block by neostigmine.

Paralysis was maintained in the sheep for 30 or 90 minutes by computer-controlled injection of gallamine, pancuronium, alcuronium or d-tubocurarine, using the integrated electromyogram as a measure of neuromuscular transmission. Neostigmine was given and the recovery time measured. In all trials the recovery rise time was no longer than two minutes, but varied between one and two minutes.

Animals↗
PubMed1980

Repeated doses of suxamethonium.

Repeated sub-apnoeic doses of suxamethonium produce increased neuromuscular block in a hand muscle, measured by integrated electromyogram. The response to the initial dose varies widely between patients. More than 50% of patients showed evidence of non-depolarising block after one dose of suxamethonium. There was a variation between the response of the hand muscle and respiratory muscles.

Child↗
PubMed1979

Beware -- the use of MAO inhibitors is increasing again.

The use of monoamineoxidase inhibitors in the treatment of depression is increasing again in Australia. This paper outlines changes in prescribing, the problems associated with monoamineoxidase (MAO) inhibitors and how they relate to the practice of anaesthesia.

Anesthesia, Inhalation↗
PubMed1976

Computer controlled muscle relaxation: a comparison of four muscle relaxants in the sheep.

Computer control of anaesthesia has been extended to include muscle relaxant drugs. Injection of d-tubocurarine, gallamine, alcuronium or pancuronium was controlled by computer to reduce the integrated electromyogram to a preset level (40 per cent of control) for one hour. A programmed level of muscle paralysis is therefore possible for use in physiological and pharmacological experiments, and in clinical practice where precise control of the degree of paralysis together with minimal dosage is advantageous.

Alcuronium↗