Ventriculojugular shunt against the direction of blood flow. II. Theoretical and experimental basis for shunting the cerebrospinal fluid against the direction of blood flow.

An experimental model for shunting the cerebrospinal fluid (CSF) to the internal jugular vein (IJV) using a valveless shunting catheter was used in two experiments to study the differences between shunting the CSF either in or against the direction of blood flow. The results of the first experiment suggested that: if the CSF is shunted to the IJV in the direction of blood flow, the intracranial pressure (ICP) will stabilize at a lower level than the venous pressure (VP); blood will regurgitate into the shunting catheter during periods of rise in the intrathoracic pressure (ITP) and during change of posture from erect to recumbent; siphonage will develop when the erect posture is assumed and will lead to CSF overdrainage and intracranial hypotension; the flow of CSF to the venous circulation will be intermittent. The results of the second experiment suggested that: if the CSF is shunted to the IJV against the direction of blood flow, the ICP will stabilize at a higher level than the VP; blood will not regurgitate into the shunting catheter during periods of rise in the ITP or during changes in posture; siphonage will not develop in the erect posture; the flow of CSF to the IJV will be continuous, and its rate will be equal to and dependent on the rate of CSF formation. It was concluded that the physiologically correct way of shunting the CSF to the IJV is against the direction of blood flow.