Biomedical subjects

R J Dempsey

Publications and source records attributed to R J Dempsey.

112 records · Page 7Linked to original sources

PubMed1982

Experimental augmentation of cerebral blood flow by mannitol in epidural intracranial masses.

Substantial morbidity and mortality from epidural hematomas continue to be seen in major centers. In spite of great improvement in the rapidity of diagnosis, preoperative treatment and surgical techniques are relatively unchanged. Nineteen anesthetized cats were monitored before and after creation of an epidural mass. Hydrogen clearance technique was used to calculate regional cerebral blood flow (rCBF) both ipsilateral and contralateral to the mass. The control group received no other treatment and showed a decrease in rCBF to as low as 56.8% of prior flow. The experimental group received 1 gm/kg/hr of mannitol and showed augmentation of rCBF to as high as 154.9% of prior flow (p less than 0.001). The effect was seen without increase in perfusion pressure or tissue edema. This study was designed to examine the parameters of rCBF after formation of an experimental epidural mass, and shows that rCBF can be increased as part of the preoperative resuscitation of such patients.

Animals↗

PubMed1982

Experimental acute hepatic encephalopathy: relationship of pathological cerebral vasodilation to increased intracranial pressure.

In clinical reports of encephalopathy and pediatric trauma, acute brain swelling has been postulated to be secondary to vasodilation of the cerebrovascular bed. Eight adult cats were studied to determine whether such pathological vasodilation was present in an experimental model of hepatic encephalopathy. All animals were anesthetized, ventilated, and monitored for intracranial pressure (ICP), arterial pressure, heart rate, arterial blood gases, temperature, and blood ammonia content. The regional cerebral blood flow (rCBF) was measured at three cortical sites by the hydrogen clearance technique. The intravenous infusion of ammonium acetate was used to produce blood ammonia levels comparable to those observed in severe Reye's syndrome. All experimental animals showed a significant increase in ICP as well as rCBF to a mean of 79.5 +/- 7.3 ml/100 g/minute. This represents a mean increase in %rCBF to 252% of control. The mean calculated cerebrovascular resistance (CVR) was noted to fall to 55 +/- 4.7% of control CVR values (p less than 0.001). This relative vasodilation was diffuse with no significant difference between hemispheres or lobes studied. Such a vasodilation, as shown by a marked fall in the resistance of the cerebrovascular bed, is a pathological response in light of the rising ICP. This suggests that pathological cerebral vasodilation may be an important cause of increased ICP in the brain suffering an acute generalized insult.

Acute Disease↗

PubMed1981

Choroid plexus cyst in the lateral ventricle causing obstructive symptoms in an adult.

This case of a rare symptomatic choroid plexus cyst in the lateral ventricle, which presented with papilledema and decreased vision, is the first such lesion found in an adult. Five earlier reported cases, all in children, are discussed, as are the limitations of computerized tomographic (CT) scanning and the need for further radiological studies to establish the diagnosis preoperatively. Metrizamide ventriculography with CT scanning is used to define the lesion and plan an operative approach.

Adult↗

PubMedDate not supplied

Cerebral infarction: assessment of patterns using ultra-fast MR contrast imaging.

We describe a rapid MR imaging technique, applying functional analysis to images obtained during the tissue transit of injected contrast material into the cerebral circulation, which has potential for assessment of the altered hemodynamics in cerebral ischemia. This technique utilized turbo-FLASH imaging maximizing the T1 relaxivity properties of gadopentetate dimeglumine with positive contrast enhancement.

Cerebral Infarction↗