Closed ventriculocisternal perfusion to determine CSF production rate and pressure.
When the rate of cerebrospinal fluid (CSF) production (Vf) is determined using the classical open ventriculocisternal perfusion technique, it is not possible to observe natural fluctuations in CSF pressure, or the effects of experimental treatments on CSF pressure, or to make inferences about CSF volume or resistance to reabsorption of CSF, because CSF pressure is fixed according to the level of the distal end of the cisternal outflow cannula. In addition, the convention of placing the distal end of the cisternal outflow cannula at the interaural line fixes CSF pressure at a value that may not be usual for the animal, thereby introducing potential causes for error in the determination of Vf. The present study describes and evaluates a method of closed ventriculocisternal perfusion that allows the simultaneous determination of Vf and CSF pressure. With this method the time to tracer equilibration was less, and the volume of distribution of the tracer was smaller than with the classical open perfusion system. CSF pressure tracings were of high fidelity showing both respiratory and cardiovascular variation. During both sedation with nitrous oxide or halothane anesthesia, Vf values using closed perfusion were similar to values previously reported using open perfusion. Vf decreased during halothane anesthesia compared with nitrous oxide sedation. No time-related change in Vf from the first measurable time period (approximately 2 h) to the end of the study (approximately 5 h) was observed.
D000758:Anesthesia; D000818:Animals; D002552:Cerebral Ventricles / Q000378:metabolism*; D002555:Cerebrospinal Fluid / Q000378:metabolism* / Q000502:physiology; D002946:Cisterna Magna / Q000378:metabolism*; D004285:Dogs; D006221:Halothane; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D009609:Nitrous Oxide / Q000494:pharmacology; D010477:Perfusion / Q000379:methods*; D011312:Pressure
D006993:Hypnotics and Sedatives; D009609:Nitrous Oxide; D006221:Halothane