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Biomedical subjects

G E Mead

Publications and source records attributed to G E Mead.

32 records · Page 2Linked to original sources
PubMed1996

Neutrophil activation in jugular venous blood during carotid endarterectomy.

OBJECTIVES: Neutrophils may play an important role in cerebral ischaemia. We investigated whether neutrophil activation can be detected in cerebral venous blood during the mild cerebral hypoxia and reperfusion that occurs during carotid cross clamping and declamping for endarterectomy. DESIGN, SETTING AND MATERIALS: The ipsilateral jugular bulb was cannulated at operation in 16 patients undergoing carotid endarterectomy. Blood was taken immediately prior to and 30 seconds following internal carotid cross clamping; then immediately prior to, 30 s and 2 m following declamping. Blood was also taken from a peripheral vein in the foot. Intracerebral oxygen saturation (CsO2) was measured continuously by near infrared cerebral spectroscopy. Neutrophil activation was measured by flow cytometric detection of fluorescence to hydrogen peroxide in unstimulated cells and phorbol myristate acetate stimulated cells, and expressed as mean fluorescent intensity (MFI). OUTCOME MEASURES: Neutrophil activation and cerebral oxygenation. MAIN RESULTS: CsO2 fell from 68% (95% Confidence interval 64%-72%) to 63% (59%-68%) following carotid cross clamping (p < 0.05, repeated measures analysis of variance). This recovered slightly during the cross clamp period to 64% but only returned to preclamp levels following declamping (p > 0.05). Neutrophil hydrogen peroxide generation by stimulated neutrophils rose significantly from 0.79 mean fluorescent intensity (0.53-1.19) to 1.46 (0.98-2.20) but no there was no further rise following cross clamp release. There was no significant neutrophil activation in the peripheral samples. CONCLUSIONS: These results indicate that even mild cerebral hypoxia is associated with priming of neutrophils in cerebral venous blood.

Aged↗
PubMed1996

How do general practitioners manage patients at risk from stroke?

This study assessed by means of a postal questionnaire how general practitioners (GPs) manage patients at risk from stroke. Of the 640 GPs sent a questionnaire, 294 (46%) replied. In patients with a recent transient ischaemic attack or minor ischaemic stroke, 24% of responding GPs would not arrange any investigations. Sixty-one per cent refer under half of their patients for further investigation, although 99% of GPs would commence aspirin. Seventy-seven per cent of GPs were aware of the benefits of carotid surgery. For patients in atrial fibrillation, most GPs (77%) thought that warfarin reduced stroke rates, but only 20% would consider commencing warfarin, although 26% would commence aspirin. In hypertensive patients, the GPs' threshold for treatment ranged from 135 to 200mmHg systolic (median 160mmHg), and from 90 to 110mmHg diastolic (median 100mmHg). Most GPs (84%) would treat isolated systolic hypertension with a median threshold of 180mmHg (range 140-240mmHg). The results of this study suggest that some patients at risk from stroke may not receive optimal investigation and treatment in the community.

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PubMed1995

Cardiopulmonary resuscitation in the elderly: patients' and relatives' views.

One hundred inpatients on an acute hospital elderly care unit and 43 of their relatives were interviewed shortly before hospital discharge. Eighty per cent of elderly patients and their relatives were aware of cardiopulmonary resuscitation (CPR). Television drama was their main source of information. Patients and relatives overestimated the effectiveness of CPR. Eighty-six per cent of patients were willing to be routinely consulted by doctors about their own CPR status, but relatives were less enthusiastic about routine consultation. Patients' and relatives' views about the appropriateness of CPR did not differ significantly. Seventeen percent of patients did not desire CPR. However, 64 per cent of patients were ultimately willing to follow their doctor's advice about the appropriateness of CPR. The conclusion reached is that mentally competent, elderly patients but not their relatives should be routinely consulted about their own desire for CPR in order to avoid resuscitating patients against their wishes. Further research is required to find out how patients would feel about resuscitation if they were terminally ill or chronically confused, and how carers would feel about resuscitating such patients.

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PubMed1994

Light-reflective cerebral oximetry and jugular bulb venous oxygen saturation during carotid endarterectomy.

A novel instrument using reflected near-infra-red light spectroscopy to measure cerebral oxygen saturation non-invasively was evaluated during carotid endarterectomy; cerebral perfusion was compared with jugular bulb venous oxygen saturation and transcranial Doppler ultrasonographic measurements. Initially, oximetry sensors with light source-detector separation distances of 10 and 27 mm were positioned over the frontal area, while a cannula positioned in the jugular bulb permitted sampling for jugular bulb venous oxygen saturation. To increase cerebral oxygen saturation sensitivity, modified sensors with light source-detector separation distances of 30 and 40 mm were relocated over the middle cerebral artery territory. The changes in cerebral and jugular bulb venous oxygen saturation, and in peak blood flow velocity before and 30 s after carotid clamping and declamping were recorded. The modified cerebral perfusion system achieved improved correlations between cerebral and jugular bulb venous oxygen saturation changes during carotid clamping and declamping (r = 0.92, P < 0.001). The correlation between change in cerebral oxygen saturation and the percentage change in peak flow velocity on both cross-clamping and declamping was equally strong (r = 0.90, P < 0.001). Near-infra-red cerebral spectroscopy reliably detects changes in cerebral oxygen saturation during carotid endarterectomy and may have wide applications in monitoring brain perfusion during neurosurgery and cardiopulmonary bypass surgery, and in closed head injury.

Blood Flow Velocity↗
PubMedDate not supplied

What factors influence patient preferences regarding cardiopulmonary resuscitation?

The aims of this study were to investigate the impact of medical and non-medical factors on the cardiopulmonary resuscitation (CPR) preferences of patients, to determine which of them are the most important to patients when considering CPR, and to compare the views of older (> or = 70 years) and younger (< 70 years) patients. We interviewed 180 patients, 86 of whom were aged 70 years or older. 'I do not want to be a burden on my family' was the most important factor for older patients, and they were more ready to leave the decision to the doctor than were the younger patients. 'I want to retain my capacity to think clearly' was most important to younger patients. In general, younger patients gave higher ratings in favour of CPR than older patients. Increased age, drug abuse, dementia, pain, poor functional status and a low likelihood of success were associated with a lower preference rating for CPR in both age groups.

Age Factors↗
PubMedDate not supplied

An informal assessment of nutritional status in acute stroke for use in an international multicentre trial of feeding regimens.

Patients with acute stroke may become malnourished because of feeding difficulties, so dietary supplementation may improve outcome. We investigated the validity and reliability of an 'eyeball' assessment of nutritional status for use in an international trial of different feeding following acute stroke. One hundred and one inpatients (mean age 75 years), of whom 40 had suffered an acute stroke, were independently observed by two medical students, a doctor and a nurse, and categorised as underweight, normal weight or overweight. Body mass index (BMI) was calculated using height and weight. Sensitivity of the informal assessment for correctly classifying the patient as underweight (BMI < 20 kg/m2), normal (20-30 kg/m2) and overweight (BMI > 30 kg/m2) ranged from 64% to 100% and specificity from 71% to 100%. Interobserver agreement between different pairs of observers was moderate to good. An 'eyeball' assessment of nutritional status is valid and reliable enough for use in a multicentre trial of feeding regimens following acute stroke.

Acute Disease↗