Biomedical subjects

D Heaviside

Publications and source records attributed to D Heaviside.

9 recordsLinked to original sources

PubMed1994

Glucose export from the brain in man: evidence for a role for astrocytic glycogen as a reservoir of glucose for neural metabolism.

We report transients of net export of glucose from brain with jugular venous glucose content exceeding arterial by up to 5.3 mmol.l-1 in 19 children undergoing cardiopulmonary bypass surgery. The magnitude of the release implies the presence of a glucose reservoir in brain, the most likely candidate being astrocytic glycogen. These data provide evidence that astrocytic glycogen can be exported as glucose, permitting spatial and temporal modulation of glucose delivery to neurons.

Astrocytes↗

PubMed1991

A practical method of serial bedside measurement of cerebral blood flow and metabolism during neurointensive care.

Acute encephalopathy is a major cause of death and neurological handicap in children. The principle aims of treatment are to provide adequate cerebral blood flow for the brain's metabolic needs and to prevent intracranial pressure rising above the level at which brain herniation occurs. Rational management requires an understanding of the pathophysiological changes in cerebral blood flow and metabolism which occur. The paucity of data on this subject reflects the perceived difficulty of measuring cerebral blood flow and cerebral metabolism in children. A modification of the Kety Schmidt technique of measuring cerebral blood flow and cerebral metabolism is described. This modification makes it possible to perform serial bedside measurements in children receiving intensive care. This method was used to perform 348 measurements in 58 children. The method was reproducible and no significant complications were encountered. The results indicated that appreciable changes in cerebral blood flow and metabolism could occur in individual patients over time, emphasising the importance of serial measurements. This technique may provide a practical means of monitoring cerebral blood flow and metabolism in very sick children receiving neurointensive care and evaluating the efficacy of treatment.

Acute Disease↗

PubMed1989

An analysis of factors predisposing to neurological injury in patients undergoing coronary bypass operations.

In a prospective study of 312 patients undergoing elective coronary bypass surgery we evaluated 50 preoperative, intraoperative and postoperative factors with the aim of identifying predisposing causes for perioperative neurological morbidity. Factors which showed a significant association with the development of neurological complications included the duration and severity of heart disease before surgery; the presence of extracoronary vascular disease; history of cardiac failure; history of diabetes; difficulty in terminating bypass; intraoperative mean arterial pressure levels of less than 40 mmHg; a large drop in haemoglobin level during surgery; prolonged stay in the intensive therapy unit after operation; and abnormalities of blood pressure control in the postoperative period. The significance of these findings is discussed and a comparison made with data available from previous studies.

Adult↗

PubMed1987

Neuro-ophthalmological complications of coronary artery bypass graft surgery.

In a prospective study of neurological complications of coronary bypass surgery, detailed pre- and post-operative bedside ophthalmological evaluation was undertaken in 312 patients. Post-operative neuro-ophthalmological complications developed in 80/312 (25.6%) patients and included: areas of retinal infarction (17.3%); retinal emboli (2.6%); visual field defects (2.6%); reduction of visual acuity (4.5%) and Horner's syndrome (1.3%). Neuro-ophthalmological complications were not observed in a control group of 50 patients undergoing major peripheral vascular surgery. Ten of 75 patients reviewed at 6 months still had detectable neuro-ophthalmological abnormalities, but functional disability occurred only in those with persistent visual field defects. Multivariate analysis revealed that extra-coronary vascular disease, severe and prolonged duration of heart disease prior to operation, and large drop in haemoglobin level during surgery may predispose to neuro-ophthalmological complications.

Adult↗

PubMed1987

Long-term intellectual dysfunction following coronary artery bypass graft surgery: a six month follow-up study.

As part of a prospective study of neurological and neuropsychological complications of coronary bypass surgery, 259 patients underwent psychometric assessment before operation and at seven days and six months after operation using a battery of 10 standard tests of intellectual function. This report describes the natural history of intellectual dysfunction soon after surgery and the incidence and functional impact of late neuropsychological impairment. The mean neuropsychological scores for the whole group remained unchanged or improved compared with levels before operation for the majority of the 10 tests. Analysis of the test scores for individuals showed that 147 of 259 (57 per cent) patients showed deterioration on at least one test score at six months. The degree of impairment was usually mild. One hundred and thirty of the 147 patients showed mild cognitive dysfunction (score deterioration on one or two tests) and only 17 patients had moderate or severe impairment (score deterioration on three or more tests). Detectable neuropsychological deterioration at six months often did not matter to the patient in functional terms. Seventy-one per cent of these patients had no significant symptoms; 27 per cent had minor symptoms and only 2 per cent were seriously disabled. Of the patients unemployed at six months, in only one case was intellectual impairment the factor preventing return to work. A search for possible predisposing factors for long-term intellectual dysfunction was made using a multivariate analysis of 91 variables for each patient. Cardiac failure before surgery and global impairment of left ventricular function were the only factors showing significant correlation.

Adult↗

PubMed1986

Neurological complications of coronary artery bypass graft surgery: six month follow-up study.

As part of a major prospective study of the neurological complications of coronary artery bypass graft surgery patients were reviewed over six months to determine the clinical course and functional impact of early postoperative complications. One hundred and ninety one out of 312 (61%) patients had developed early postoperative disorders. At six months 165 of the 191 patients with early neurological complications were reviewed. Of the 165, 85 still had detectable neurological signs, but these were often minor and of little functional importance. Only 10 patients had neurological disability at six months, and this was major in only four patients, all of whom had suffered major perioperative stroke. No patient with non-disabling neurological complications in hospital became functionally impaired on returning home. Neurological disorders are not a major cause of failure to return to work by six months after coronary artery bypass surgery. Of 139 patients who were of working age and had not returned to work by six months, only four were prevented by neurological injury related to surgery. The long term prognosis for early neurological disorders after coronary artery bypass surgery is usually favourable, except in those patients who have sustained major perioperative stroke.

Cerebrovascular Disorders↗

PubMed1986

Early intellectual dysfunction following coronary bypass surgery.

As part of a major prospective study of neurological and psychological complications of coronary artery bypass graft surgery, involving 312 patients, detailed psychometric testing was carried out before and after operation on 298 patients using a battery of 10 standard tests of intellectual function. This report is concerned with the early neuropsychological dysfunction detectable one week after operation. Two hundred and thirty-five patients (79 per cent of the cohort) showed impairment in some aspect of cognitive function at the seventh day after operation. Only 63 patients (21 per cent) showed no deterioration from levels before operation in any of the 10 test scores. One hundred and twenty-three of the patients whose scores deteriorated had no symptoms while in hospital. Eighty-nine patients complained of cognitive impairment, and 23 patients were considered to be overtly disabled by their intellectual dysfunction, during the period soon after operation. There is therefore a high incidence of early cerebral dysfunction detectable by psychometric testing following coronary artery bypass graft surgery. Often this was not of sufficient severity to cause serious concern to the patients or to interfere with their everyday activities in the hospital environment.

Adult↗

PubMed1985

Early neurological complications of coronary artery bypass surgery.

A prospective study of 312 patients undergoing elective coronary artery bypass surgery was undertaken to determine the incidence, severity, and functional impact of postoperative neurological complications. Detailed evaluation of the patients showed that neurological complications after surgery were common, occurring in 191 of the 312 patients (61%). Although such a high proportion of the total developed detectable changes, serious neurological morbidity was rare. Neurological disorders resulted in death in only one patient (0.3%) and severe disability in only four (1.3%). Forty eight patients were mildly disabled during the early postoperative period, and the remaining 138 with neurological signs had no serious functional disability. The postoperative neurological disorders detected included one death from cerebral hypoxic damage. Prolonged depression of conscious level was observed in 10 patients (3%) and definite stroke in 15 (5%); 78 (25%) developed ophthalmological abnormalities and 123 (39%) primitive reflexes; postoperative psychosis was observed in four (1%); and 37 (12%) developed disorders of the peripheral nervous system. The incidence of serious neurological problems such as fatal cerebral damage, stroke, and brachial plexopathy is in accordance with experience elsewhere. Lesser abnormalities, whose detection required detailed neurological examination, were much commoner than expected from previous reports.

Adult↗

PubMedDate not supplied

Neurologic and neuropsychological morbidity following major surgery: comparison of coronary artery bypass and peripheral vascular surgery.

As part of a prospective study of the neurologic and neuropsychological complications of coronary artery bypass graft surgery, 312 patients were compared with a control group of 50 patients undergoing major surgery for peripheral vascular disease. The purpose of comparing the 2 groups was to determine to what extent neurologic complications after heart surgery can be attributed to cardiopulmonary bypass. The 2 groups were similar with respect to age, preoperative neurologic and intellectual status, anesthetic methods, duration of operation, perioperative complications, and time spent in the intensive therapy unit. Certain potential risk factors for cerebrovascular disease were more common in the control than the coronary bypass patients. The important difference between the 2 groups was that only the latter group underwent cardiopulmonary bypass. In this group 191 of 312 (61%) and 235 of 298 (79%), respectively, developed early neurologic and neuropsychological complications. By the time of hospital discharge 17% had neurologic disability and 38% had significant neuropsychological symptoms. In the control group 9 of 50 (18%) developed neurologic complications resulting largely from trauma to lower limb sensory nerves. Two patients developed primitive reflexes. Fifteen of 48 (31%) showed neuropsychological impairment on 1 or 2 subtest scores. Moderate or severe intellectual dysfunction was not seen in the control patients in contrast to the 24% thus affected in the coronary bypass group. The difference in frequency and severity of central nervous system complications between the 2 groups is likely to reflect cerebral injury resulting from cardiopulmonary bypass.

Adult↗