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Biomedical subjects

P L Reilly

Publications and source records attributed to P L Reilly.

9 recordsLinked to original sources

The relative effects of hypoxic hypoxia and carbon monoxide on brain function in rabbits.

New Zealand white rabbits were exposed to control conditions (n = 11), or to either a progressive hypoxic hypoxia produced by dilution of oxygen (O2) with nitrogen (n = 10) or a 1% carbon monoxide (CO) admixture for 15 min (n = 11). Both exposures caused a significant increase in cerebral blood flow (CBF) of up to 300% such that O2 delivery to the brain was unchanged. In the hypoxia group, a cortical somatosensory evoked response (CSER) was unaffected until the arterial O2 tension was below 20 mmHg. At this time, the rabbits became hypotensive, O2 delivery to the brain decreased dramatically and the CSER could not be elicited. In contrast, despite the maintenance of O2 delivery to the brain during and after the CO exposure, the CSER voltages were halved during the exposure and only recovered to about 80% of baseline subsequently. We conclude that the primary toxicity of CO to the brain in rabbits is not due to a reduction in O2 delivery.

Animals

Head injuries in infants and young children: the value of the Paediatric Coma Scale. Review of literature and report on a study.

The normal verbal and motor responses embodied in the standard Glasgow Coma Scale (GCS) are not achievable during the first few years of life. The recent literature contains numerous reports of attempts to devise scales of responses quantitating the conscious level in infants and young children, both for research purposes and as clinical guides; some of these scales incorporate items, e.g. brainstem reflexes, that are not included in the GCS. We have reported on a simple paediatric version of the GCS, which uses the standard scale with minor modifications in the verbal component, and sets realistic age-related normal responses. This has been tested prospectively in a series of 60 head-injured infants and children (age range 0-72 months). Of 6 cases recorded as comatose 6 h after injury, 4 have confirmed or suspected residual disabilities. Of 35 cases considered to be fully conscious at 6 h, 31 have made good recoveries and only 1 has suspected residual disabilities. The study suggests that the scale accords with the realities of neurological immaturity, and confirms that it can be used in routine paediatric practice. For comparative therapeutic trials, the conscious level in infants has limited value as an index of brain injury, and should be complemented by other indices, such as brainstem reflexes.

Brain

Frontofacial advancement with a free flap: deadspace versus drainage.

Presented is an adult case of Crouzon's syndrome undergoing a single stage frontofacial advancement where the employment of a microvascular free flap for extradural deadspace obliteration and to seal any communication with the nose may have contributed to the development of a major extradural infection.

Adult

Neuropsychologic outcome after craniofacial fracture.

Forty eight patients with facial fractures resulting from trauma were admitted to a Plastic Surgical Unit. The fractures were treated on standard lines and ten of the patients required craniotomy for CSF rhinorrhea or repair of depressed frontal fractures. Neuropsychologic assessment was carried out on all patients approximately 17 months after the initial injury. An assessment of the extent to which the trauma had affected the personality and social adjustment of each individual was also carried out at that time. In four patients there was no evidence of any neuropsychologic impairment on any of the tests administered. The neuropsychologic deficits were most noticeable in those who had suffered a cranial fracture. In patients with facial fractures but no evidence of cranial fractures, there was no association between neuropsychologic impairment and site of injury. Loss of consciousness was associated with poor social adjustment and a marked change in personality. The best predictor of subsequent neuropsychologic deficits and social maladjustment was found to be the Glasgow Coma Score at the point of admission to the hospital after injury. It is concluded that with this type of injury careful neuropsychologic assessment is important in identifying the subtle deficits that might otherwise remain undetected.

Adolescent

Vascular reactivity in the primate brain after acute cryogenic injury.

The effects of an acute cryogenic injury on cerebral flow (CBF) and cerebral vascular reactivity were studied in 12 anaesthetised, ventilated baboons. Autoregulation, defined in this study as intact with a greater than 20% change in cerebrovascular resistance in response to a change in cerebral perfusion pressure, was tested before the lesion by arterial hypotension. Intact autoregulation was found in half the animals, but all animals showed an increase in CBF with hypercarbia. The cryogenic lesion was followed by a marked rise in intracranial pressure, and a fall in CBF which was only partly related to the status of autoregulation beforehand. After injury, arterial hypertension caused an increase in cerebrovascular resistance of more than 20% in half the animals. This response was not related to the presence of autoregulation before the lesion, and was accompanied by a greater impairment of the cerebrovascular response to carbon dioxide, more severe brain oedema, and lower cerebral oxygen consumption, than in the remaining baboons which had a pressure passive response to arterial hypertension. This study confirms that the failure of CBF to increase with arterial hypertension may indicate severe brain damage rather than intact physiological autoregulation.

Animals

Patients with head injury who talk and die.

Of 66 patients with head injuries who had talked at some time after injury, 25% did not have intracranial haematoma at necropsy. Most of these had raised intracranial pressure (I.C.P.), and the commonest finding was local swelling related to contusions. Almost half of the non-haematoma cases had ischaemic or hypoxic brain damage, usually without contusions; 3 were children who had had status epilepticus. Fatality without raised I.C.P. was most often due to meningitis. In deteriorating patients without haematoma mortality and morbidity might be reduced by more diagnosis and treatment, particularly of raised I.C.P.

Adolescent

Hypocapnia and intracranial volume-pressure relationship. A clinical and experimental study.

The effect of induced hypocapnia was observed, during intraventricular pressure monitoring, in five patients with chronically increased intracranial pressure (ICP) and in five baboons with acutely raised ICP. The volume-pressure response (VPR) was used as a measure of intracranial elastance (inverse compliance), an index of residual compensatory capacity. The VPR is the acute increase in mean ICP that occurs in response to a constant volume increment to ventricular cerebrospinal fluid. In the patients, hypocapnia produced a decrease in the VPR that was proportional to the decrease in ICP; in the baboons, ICP was substantially decreased with minimal change in the VPR. Both observations indicate that hypocapnia, though it decreases ICP, does not selectively decrease intracranial elastance. This may be a limiting factor in the use of hypocapnia in the management of raised ICP.

Animals