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Abstract

An intraoperative and perioperative method and several representative apparatus designs therefor for the reduction of fluid and tissue movement, where said fluid includes but is not limited to plasma, extracellular fluid, intracellular fluid, cerebrospinal fluid, and blood; and said tissue includes but is not limited to central nervous system tissue. An application of particular import in neurosurgical procedures is the intraoperative control of cerebral and spinal cord edema and the reduction of respiration-induced tissue movement. The method of the present invention, as applied to neurosurgical edema reduction, involves control of the pressure gradient between the central nervous system (CNS) and the ambient pressure. The physiologic pressure gradient between the CNS and the ambient pressure is termed the intracranial pressure (ICP) and is normally maintained at approximately 14 mmHg. The ICP may be decreased, normal, or increased as a result of any of various pathologic conditions which may indicate neurosurgical intervention. A significant complication of neurosurgical procedures is edema of the exposed nervous tissue. Control, including reduction and/or reversal, of the CNS-ambient pressure gradient eliminates the hydrostatic contribution to the generation of cerebral edema. By appropriate modulation of the applied pressure gradient, the dynamic component of the intracranial-ambient pressure gradient associated with respiration is canceled, reducing or eliminating intraoperative tissue movement. This is of particular utility in microneurosurgical procedures and in neurosurgical procedures involving placement of electrodes. The apparatus facilitates the control of the pressure gradient between the CNS and the ambient pressure and may be implemented as any of numerous possible equivalent designs, two representative embodiments including (1) a hypobaric chamber applied to a section of the unopened portion of the calvarum and extending to include the entire caudal portion of the body and (2) a hyperbaric chamber affixed to the head to apply pressure to the exposed cerebral surface. The method and apparatus of the present invention are additionally efficacious in the control of edema in other surgical procedures. Furthermore, the method and apparatus of the present invention are effective in the control of hemorrhage.

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First Claim