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Biomedical subjects

J M Gibbs

Publications and source records attributed to J M Gibbs.

At least 37 records · Page 2Linked to original sources
PubMed1985

The effects of L-DOPA on regional cerebral blood flow and oxygen metabolism in patients with Parkinson's disease.

Studies performed on 18 patients with Parkinson's disease and 6 control subjects have shown that acute administration of L-DOPA in clinically effective doses gives rise to a diffuse increase in regional cerebral blood flow without accompanying stimulation of regional oxygen utilization. The data suggest that this rise in rCBF is caused by vasodilatation due to a direct action of the drug on the cerebral blood vessels. The effect of L-DOPA on rCBF did not correlate with the degree of clinical improvement seen in each patient after treatment. The therapeutic effect of L-DOPA in the brain was not reflected in any change of regional cerebral oxygen utilization as measured by our technique. We suggest that the pharmacological actions of L-DOPA in the brain take place on at least two different levels.

Adult↗
PubMed1985

Clinical comparison of atracurium and alcuronium in gynaecological surgery.

In a double-blind, prospective, randomised trial in 51 female patients, atracurium 0.6mg/kg provided acceptable intubating conditions more rapidly than did alcuronium 0.25 mg/kg. Atracurium produced more profound neuromuscular twitch suppression than alcuronium. The effect of atracurium was longer-lasting than that of alcuronium (32 minutes and 22 minutes respectively to achieve 10% recovery) and it took slightly longer to reverse with neostigmine. Seven patients in the atracurium group who underwent short surgical procedures required supplementary neostigmine to achieve adequate reversal. Two cases of sinus bradycardia were noted in the atracurium group, but hypotension was not a clinical problem in any patient. Atracurium appears to be a useful relaxant, but a smaller dose than that used here should be chosen for short procedures.

Alcuronium↗
PubMed1984

The control of postoperative pain by EMG biofeedback in patients undergoing hysterectomy.

Electromyographic (EMG) measurements from the forehead and rectus abdominis areas were undertaken in a group of patients presenting for elective hysterectomy. The efficacy of EMG auditory feedback as a means of inducing relaxation so as to modify the dose of postoperative analgesia was examined and compared with the dose in subjects having EMG measurements without audiofeedback. Comparison was also made with a group of subjects who did not have EMG measurements. Subjects in those groups who were given relaxation instruction received less postoperative analgesia than subjects not receiving this treatment. A reduction in EMG activity was demonstrated with auditory feedback, but this did not relate directly to reduced analgesic administration after surgery.

Adult↗
PubMed1984

A hypersensitivity screening clinic following untoward reactions to anaesthesia.

Anaphylactoid or anaphylactic reactions to drugs used during general anaesthesia are potentially life threatening. It is important that they be differentiated from other types of cardio-respiratory collapse. At present a detailed history of the time sequence of events in relation to drug administration is of a greatest importance. Retrospective skin testing may then indicate which agent was involved, although false positives and false negatives may occur. Forty-nine patients who presented with a history of collapse during anaesthesia over a five year period were skin tested. Positive results were obtained in 22, ten gave inconclusive test results but a strongly suggestive history. The remainder were considered to have other causes for their clinical presentation. The incidence of severe reactions confirmed by history and by skin testing in this community is approximately 1:4000.

Anesthesia↗
PubMed1984

Evaluation of cerebral perfusion reserve in patients with carotid-artery occlusion.

Regional cerebral blood flow, oxygen utilisation, fractional oxygen extraction, and cerebral blood volume were measured by positron emission tomography in thirty-two patients with internal-carotid-artery occlusion. In most cases, and reduction in cerebral blood flow in the territory distal to an occluded carotid artery was matched to diminished cerebral metabolic demands. Cerebral blood flow was inappropriately low in only six patients, in whom regional oxygen utilisation was maintained by a compensatory rise in oxygen extraction ratio. The frequent finding of high cerebral blood volume distal to occluded vessels was consistent with a state of focal vasodilatation in response to diminished cerebral perfusion pressure. Analysis of the relation between cerebral blood flow, blood volume, and oxygen extraction ratio suggested that the reduction in cerebral perfusion pressure, and hence circulatory reserve, could be most reliably predicted by the ratio of cerebral blood flow to blood volume. By identifying those patients with carotid occlusion who are most compromised on haemodynamic grounds, combined measurement of cerebral blood flow and blood volume should be valuable in selection of candidates for extracranial-intracranial bypass surgery.

Arterial Occlusive Diseases↗
PubMed1984

Evaluation of cerebral perfusion reserve in patients with carotid-artery occlusion.

Regional cerebral blood flow, oxygen utilisation, fractional oxygen extraction, and cerebral blood volume were measured by positron emission tomography in thirty-two patients with internal-carotid-artery occlusion. In most cases, any reduction in cerebral blood flow in the territory distal to an occluded carotid artery was matched to diminished cerebral metabolic demands. Cerebral blood flow was inappropriately low in only six patients, in whom regional oxygen utilisation was maintained by a compensatory rise in oxygen extraction ratio. The frequent finding of high cerebral blood volume distal to occluded vessels was consistent with a state of focal vasodilatation in response to diminished cerebral perfusion pressure. Analysis of the relation between cerebral blood flow, blood volume, and oxygen extraction ratio suggested that the reduction in cerebral perfusion pressure, and hence circulatory reserve, could be most reliably predicted by the ratio of cerebral blood flow to blood volume. By identifying those patients with carotid occlusion who are most compromised on haemodynamic grounds, combined measurement of cerebral blood flow and blood volume should be valuable in selection of candidates for extracranial-intracranial bypass surgery.

Adult↗
PubMed1984

Positron emission tomographic studies in aging and cerebrovascular disease at Hammersmith hospital.

This paper attempts to place into perspective the present state of clinical investigation with PET in neurology. To this end we briefly review the work of the neurology group of the MRC Cyclotron Unit at Hammersmith Hospital, by reference to studies performed in normal subjects and in patients with cerebrovascular disease. Based on the current understanding of human physiology in health and disease as a result of this new method of clinical measurement in humans, we speculate on some possible future developments and present constraints in the application of PET to clinical research.

Acute Disease↗
PubMed1984

Positron emission tomography of the brain: new possibilities for the investigation of human cerebral pathophysiology.

In the foregoing an overview of positron emission tomography has been presented. Its theoretical, technical, and methodological implications, as well as its clinical applications have been outlined. The emphasis has been on the quantitative aspects of the method and its usefulness is investigating normal and pathological functions of brain tissue. Although the potential of this new research technique is obvious, many theoretical and practical difficulties still need to be solved. Nevertheless it provides an opportunity to bridge the gap between basic experimental research and clinical medicine.

Aging↗
PubMed1984

Measurement of cerebral blood flow using bolus inhalation of C15O2 and positron emission tomography: description of the method and its comparison with the C15O2 continuous inhalation method.

This article describes a rapid method for the regional measurement of cerebral blood flow using a single breath of C15O2 and positron emission tomography. The technique is based on the bolus distribution principle and utilises a reference table for the calculation of flow. Seven subjects were studied using both this method and the C15O2 continuous inhalation steady-state technique. The single-breath method gave flow values 20% higher than those obtained using the steady-state method. A simulation study was performed in an attempt to define the reasons for the difference between the two techniques. Estimations were made of identified sources of error in the measurement of regional cerebral blood flow using the single-breath technique and compared with results from a similar study previously described for the steady-state technique. However, further comparative studies will be necessary to satisfactorily explain the difference between both techniques.

Adult↗
PubMed1984

A computer-based audit of anaesthetic registrar training.

A computerised summary of all anaesthetics administered by the North Canterbury Hospital Board's Department of Anaesthesia was used to examine the work patterns of registrars in the vocational training program over a two-year period. There was a considerable difference in the case load of some registrars even allowing for holidays and other leave. The exposure to surgical specialities and the degree of supervision were examined and problem areas identified. From a relatively simple data base it is possible to obtain information of value in the monitoring of a graduate training program.

Anesthesiology↗