Closed recirculatory spinal subarachnoid perfusion for determining CSF dynamics.
ABSTRACT A new method for determining the rates of cerebrospinal fluid (CSF) production under nonsteady-state conditions, namely, closed recirculatory spinal subarachnoid perfusion, was used to determine the effect of enflurane on the rate of CSF production in dogs. Considerable variability in results was observed such that there was no statistical difference in rates of production among animals that received enflurane 2.2%, enflurane 2.2% and nitrous oxide 60% to 70%, enflurane 3.2% and nitrous oxide 60% to 70%, or nitrous oxide 60% to 70% (controls). Possible sources of variability were sought in additional studies using a modification of the new method, and in an in vitro model. The results were compared to those obtained using an established method for determining rates of CSF production, namely, open ventriculocisternal perfusion. It was concluded that the sources of variability in the closed recirculatory method relate in part to adherence of the fluorescein-conjugated albumin tracer to glass and other surfaces, and to uneven flow and distribution of the tracer in the recirculatory system. When the open ventriculocisternal perfusion method was used, consistent results were obtained, demonstrating that CSF production rate increased significantly in animals that received enflurane. The authors conclude that the new closed recirculatory method is less reliable than the classical open perfusion method.
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ABSTRACT: Considerable difference of opinion has arisen as to whether intravenously administered steroids affect cerebrospinal fluid (CSF) production in the acute laboratory animal undergoing ventriculocisternal perfusion. Our experiments with ventriculocisternal perfusion in dogs indicate that, when given intravenously, neither dexamethasone, methylprednisolone, hydrocortisone, nor aldosterone result in a significant, acute effect upon CSF production. Similarly, CSF absorption and outflow resistance mechanisms are not acutely affected by intravenous methylprednisolone, hydrocortisone, and aldosterone. Dexamethasone also probably does not produce an immediate effect upon CSF absorption.Journal of Neurosurgery 05/1979; 50(4):477-82. · 3.15 Impact Factor
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ABSTRACT: The effect of spinal fluid pressure on cerebrospinal fluid (CSF) formation was measured in rabbits and cats. A decreased rate of CSF production with increased perfusion pressure was found, which was best illustrated by paired comparisons in individual animals during ventriculocisternal perfusion at both low (−5 to −10 cm H2O) and high (20–25 cm H2O) perfusion pressure. Each animal was perfused at either pressure for 2 hr (rabbits) or 2.5 hr (cats) for steady-state measurements. After a gradual change in hydrostatic pressure, perfusion continued for an additional 1.5 hr (rabbits) or 2 hr (cats) when steady-state measurements were repeated. The mean rate of CSF production decreased in rabbits from 0.0081 to 0.0045 ml/min after the perfusion pressure was elevated. This effect was independent of whether the animals were perfused initially under high or low pressure. In cats, after a similar increase in perfusion pressure, the mean rate of CSF formation decreased from 0.0212 to 0.0102 ml/min.Experimental Neurology 08/1971; 32(1):30-40. · 4.65 Impact Factor
- Journal of Neurosurgery 10/1974; 41(3):350-5. · 3.15 Impact Factor