title: Cerebral microdialysis methodology--evaluation of 20 kDa and 100 kDa catheters.
abstract: Microdialysis monitoring of cerebral metabolism is now performed in several neuro-intensive care units. Conventional microdialysis utilizes CMA70 catheters with 20 kDa molecular weight cut-off membranes enabling the measurement of small molecules such as glucose, lactate, pyruvate and glutamate. The CMA71 100 kDa molecular weight cut-off microdialysis catheter has recently been introduced to allow detection of larger molecules such as cytokines. The objective of this study was to perform in vitro and in vivo testing of the CMA71 microdialysis catheter, comparing its performance with the CMA70. In vitro comparison studies of three of each catheter using reference analyte solutions, demonstrated equivalent recovery for glucose, lactate, pyruvate and glutamate (range 94-97% for CMA70 and 88-103% for CMA71). In vivo comparison involved intracranial placement of paired CMA70 and CMA71 catheters (through the same cranial access device) in six patients with severe traumatic brain injury. Both catheters were perfused with CNS Perfusion Fluid without dextran at 0.3 microl min-1 with hourly sampling and bedside analysis on a CMA600 microdialysis analyser. The two catheters yielded equivalent results for glucose, lactate, pyruvate, glutamate and lactate/pyruvate ratio. CMA71 microdialysis catheters can, therefore, be used for routine clinical monitoring of extracellular substances, as well as for their intended research role of larger molecular weight protein sampling.
authors.affiliation: Department of Neurosurgery, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2QQ, UK. pjah2@cam.ac.uk
authors.forename: P J
authors.initials: PJ
authors.lastname: Hutchinson
authors.forename: M T
authors.initials: MT
authors.lastname: O'Connell
authors.forename: J
authors.initials: J
authors.lastname: Nortje
authors.forename: P
authors.initials: P
authors.lastname: Smith
authors.forename: P G
authors.initials: PG
authors.lastname: Al-Rawi
authors.forename: A K
authors.initials: AK
authors.lastname: Gupta
authors.forename: D K
authors.initials: DK
authors.lastname: Menon
authors.forename: J D
authors.initials: JD
authors.lastname: Pickard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D001930:Brain Injuries / Q000175:diagnosis* / Q000378:metabolism*; D002404:Catheterization; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D017551:Microdialysis / Q000295:instrumentation* / Q000379:methods; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D018377:Neurotransmitter Agents; D005947:Glucose