Biomedical subjects
J M Gibbs
Publications and source records attributed to J M Gibbs.
Cerebral neoplastic angioendotheleosis complicated by hypercalcaemia.
This is a case report of a 67 year old man who presented with a fluctuating level of consciousness and myoclonic jerks caused in part by hypercalcaemia. The diagnosis of cerebral neoplastic angioendotheleosis was only made later on brain biopsy and is the first report of the occurrence of hypercalcaemia in neoplastic angioendotheleosis.
Cerebral blood flow, blood volume and oxygen utilization. Normal values and effect of age.
Regional cerebral blood flow (CBF), oxygen extraction ratio (OER), oxygen utilization (CMRO2) and blood volume (CBV) were measured in a group of 34 healthy volunteers (age range 22-82 yrs) using the 15O steady-state inhalation method and positron emission tomography. Between subjects CBF correlated positively with CMRO2, although the interindividual variability of the measured values was large. OER was not dependent on CMRO2, but highly negatively correlated with CBF. CBV correlated positively with CBF. When considering the values of all the regions of interest within a single subject, a strict coupling between CMRO2 and CBF, and between CBF and CBV was found, while OER was constant and independent of CBF and CMRO2. In 'pure' grey and white matter regions CMRO2, CBF and CBV decreased with age approximately 0.50% per year. In other regions the decline was less evident, most likely due to partial volume effects. OER did not change or showed a slight increase with age (maximum in the grey matter region 0.35%/yr). The results suggest diminished neuronal firing or decreased dendritic synaptic density with age.
How safe is anaesthesia in New Zealand?
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The New Zealand scene: implications of no fault accident compensation.
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No fault compensation for personal injury in New Zealand: some implications for anaesthetists.
In recent years, there has been an increase in medico-legal and disciplinary actions against doctors, some involving anaesthetists. While this has occurred at a time of increasing questioning of doctors' decisions, in New Zealand there has been the added dimension of a major change in the law related to personal injury. Under the provisions of the Accident Compensation Act there are no grounds for a civil action against a doctor in respect of a medical misadventure. The only provision for recompense is through the Accident Compensation Corporation. With the removal of the punitive aspect of civil actions against doctors, there has been an increase in complaints through other channels. The anaesthetist is particularly vulnerable because of the immediacy with which an adverse event is likely to cause obvious harm to a patient. This can only be countered by high standards of practice, together with careful record keeping.
Cerebral haemodynamic changes after extracranial-intracranial bypass surgery.
Regional cerebral blood flow, oxygen utilisation, fractional oxygen extraction, and cerebral blood volume were measured by positron emission tomography in twelve patients with carotid artery occlusion. Follow-up studies were carried out at a mean interval of eleven weeks after extracranial-intracranial bypass surgery. Clinical improvement was observed in three patients who had presented with frequent transient ischaemic attacks. One patient with multiple vascular occlusions suffered a stroke at the time of surgery. Follow-up studies showed an increase of regional cerebral blood flow in only two of the twelve patients. In the group as a whole, there was no significant change of cerebral blood flow, oxygen consumption or fractional oxygen extraction after bypass surgery. The most consistent post-operative change, observed in eleven of the twelve patients, was a fall of cerebral blood volume in the cortical territory of the bypassed carotid artery (p less than 0.01). This effect was most marked in patients with bilateral carotid occlusion, in whom there was often an accompanying fall of blood volume in the contralateral hemisphere. The post-operative findings were consistent with an increase of regional cerebral perfusion pressure as a result of the bypass procedure. Although this effect is potentially of value, those patients with most to gain from bypass surgery may also run the highest risk of peri-operative cerebral ischaemia.
A clinical comparison of atracurium and vecuronium in women undergoing laparoscopy.
In a double-blind, prospective, randomised trial in 30 women undergoing laparoscopy, atracurium and vecuronium were compared in equipotent (2 X ED95) doses. In the atracurium group, first twitch depression was significantly greater at one minute, and degree of fade significantly greater at one and two minutes, but thereafter neuromuscular monitoring showed no significant difference between the groups. Clinically there was no significant difference between the drugs. Mild intraoperative hypotension was equally common in both groups as was sinus bradycardia. Reversal and recovery were comparable in the two groups. Neostigmine was required in all patients and in three (one atracurium, two vecuronium) a second dose was required in all patients and in three (one atracurium, two vecuronium) a second dose was administered on clinical grounds. Antagonism of the neuromuscular block is required with surgery of this duration despite the intermediate duration of action of the relaxant drugs.
The Anaesthetic Mortality Assessment Committee 1979-1984.
A review of 324 cases reported to the Anaesthetic Mortality Assessment Committee over a five year period confirms a low incidence of cases associated primarily with anaesthesia. The committee has identified potential problem areas affecting anaesthesia which require continued vigilance on the part of the anaesthetist. These include the fluid balance of patients, the potential for hypothermia, altered patterns of drug action in the elderly and critically ill and the influence of other disease processes-notably those affecting the heart. As well there are the rare problems more directly associated with anaesthesia such as hypersensitivity reactions and malignant hyperpyrexia. Technical problems during anaesthesia such as misplacement of the endotracheal tube are not commonly associated with death, but because they are preventable, are of particular importance.
Regional cerebral blood flow and oxygen metabolism in dementia due to vascular disease.
Regional cerebral blood flow (CBF), oxygen utilisation (CMRO2) and fractional oxygen extraction (OER) were measured by positron emission tomography in patients with multi-infarct dementia. A matched reduction of both CBF and CMRO2 in the majority of patients indicated that in general, reduced cerebral perfusion in this condition is appropriate for the reduced metabolic demands of a damaged brain. Only in a very small minority of patients with dementia associated with bilateral carotid artery occlusion was CBF inappropriately low and OER raised. In these exceptional cases with critical cerebral perfusion, surgical measures to increase CBF could theoretically arrest or slow down the progress of dementia.
The learning process in medical education.
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Cerebral haemodynamics in occlusive carotid-artery disease.
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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.
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.
Use of positron emission tomography scanning in cerebral ischemia.
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A hospital viewpoint: what are patients for (or doctors for that matter)
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Preservation of the pulmonary vasoconstrictor response to alveolar hypoxia during the administration of halothane to dogs.
The action of halothane on the pulmonary vasoconstrictor response to unilateral alveolar hypoxia was studied in two groups of dogs. In the first group the redistribution of blood flow between the two lungs was studied with a radioactive isotope method, which provided intermittent measurements, whilst in the second group the distribution of blood flow was observed continuously. In both groups there was no significant alteration of the hypoxic vasoconstrictor response with inspired halothane concentrations varying from 0.5 to 1.5%.