Journal of neurosurgery
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Journal of neurosurgery · Dec 1985
Cerebral effects of isovolemic hemodilution with a hypertonic saline solution.
In view of a growing interest in the resuscitative use of hypertonic saline solutions, the authors have examined the cerebral effects of isovolemic hemodilution carried out over 1 hour (hematocrit decreased from 40% to 20%, stable arterial and right arterial pressures), using a hypertonic lactated Ringer's solution (HT-LR: Na+ 252 mEq/liter, osmolality 480 mOsm/liter). Experiments were carried out in anesthetized ventilated rabbits. Measured variables included cerebral blood flow (using the H2 clearance method), intracranial pressure (ICP), the electroencephalogram, spinal cord and skeletal muscle water content (%H2O), and the specific gravity of small (10- to 30-mg) tissue samples taken from different areas of the left hemisphere (including the cortex, thalamus, internal capsule, and hippocampus). ⋯ By contrast, rabbits with hemodilution by normal saline showed no changes in either %H2O or specific gravity, but had significant increases in ICP (3.3 +/- 1.3 mm Hg). Cerebral blood flow increased in all animals hemodiluted with either HT-LR or normal saline by a combined average of +29 ml/100 gm/min. Although these studies were performed in neurologically normal animals, the combination of cerebral changes seen with HT-LR (cerebral dehydration, less peripheral edema, decreased ICP but with increased cerebral blood flow) suggests that this approach may have some advantages over the use of isotonic fluids, and may have some utility in the resuscitation of head-injured patients.
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Journal of neurosurgery · Dec 1985
Acute brain edema in fatal head injury: analysis by dynamic CT scanning.
Dynamic computerized tomography (CT) was performed on 42 patients with acute head injury to evaluate the hemodynamics and to elucidate the nature of fatal diffuse brain bulk enlargement. Patients were divided into two groups according to the outcome: Group A included 17 nonfatally injured patients, eight with acute epidural hematomas and nine with acute subdural hematomas; Group B included 25 fatally injured patients, 16 with acute subdural hematomas and nine with bilateral brain bulk enlargement. Remarkable brain bulk enlargement could be seen in all fatally injured patients with acute subdural hematoma. ⋯ Severe diffuse brain damage confirmed by follow-up CT scans and uncontrollable high intracranial pressure were noted in the fatally injured patients. Brain bulk enlargement following head injury originates from acute brain edema and an increase of cerebral blood volume. In cases of fatal head injury, acute brain edema is the more common cause of brain bulk enlargement and occurs more rapidly than is usually thought.
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Journal of neurosurgery · Dec 1985
Delayed CSF lavage for arteriographic and morphological vasospasm after experimental SAH.
Irrigation of the subarachnoid space after aneurysmal subarachnoid hemorrhage (SAH) has been reported to alleviate subsequent arterial vasospasm. The authors have investigated the effect of lavage of the cerebrospinal fluid (CSF) space in the two-hemorrhage canine model of vasospasm. Twelve dogs had basilar cistern lavage with 120 cc of artificial CSF 24 hours after each of two SAH's, and 12 control dogs had two sequential SAH's without intervening lavage of clot. ⋯ It appears that cisternal lavage 24 hours after hemorrhage in this model has no effect on the angiographic, neurological, or most morphological sequelae of SAH, in spite of evidence for removal of clot as seen at sacrifice. Any postulated interaction of clot and vessel resulting in chronic vasospasm must occur before this time. Evaluation of the effect of much earlier lavage (for instance, 1 hour after hemorrhage) may elucidate the point at which vasospasm is instigated after SAH, and help in determining what factors cause vasospasm.
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Journal of neurosurgery · Dec 1985
Cerebrovascular effects of hypocapnia during adenosine-induced arterial hypotension.
Profound arterial hypotension is a commonly used adjunct in surgery for aneurysms and arteriovenous malformations. Hyperventilation with hypocapnia is also used in these patients to increase brain slackness. Both measures reduce cerebral blood flow (CBF). ⋯ Hypocapnia with hypotension resulted in small but statistically significant reductions in all regional blood flows, most notably in the brain stem. The reported effects of hypocapnia on CBF during arterial hypotension vary depending on the hypotensive agents used. Profound hypotension induced with adenosine does not eliminate CO2 reactivity, nor does it lower blood flow to ischemic levels in this model, even in the presence of severe hypocapnia.