Microdialysis In Patients Research Articles

グロセロール含有物質の消化管内投与による脳組織内グリセロール値の非特異的上昇

In recent years, the development of secondary brain damage and the derangement of neurochemical parameters have been monitored by microdialysis in patients experiencing severe head injuries. Glycerol is regarded as a potential marker for membrane phospholipid degradation and can provide information on the integrity of the blood brain barrier. We introduce a case in which a marked elevation of interstitial glycerol was induced by the exogenous administration of a glycerol-containing agent. A 25-year-old man who had been in a motorcycle accident was admitted to our hospital with a unilateral dilated and fixed pupil and a Glasgow Coma Scale score of three. Computed tomographic scans showed a large left subdural hematoma, a subsequent midline shift, and generalized edema. An emergency craniotomy was performed to remove the hematoma. The patient was then prepared for multisensory monitoring using microdialysis. A microdialysis catheter was inserted in the left frontal lobe. After a routine enema (containing 85% glycerol), a marked increase in the amount of glycerol within the dialysate was measured. This event occurred while the patient was in as stable a condition as could be expected, under the circumstances. An increase in interstitial glycerol in the injured tissue is most likely due to an impaired blood-brain-barrier. Thus, the interstitial glycerol concentration was corrupted by the exogenous glycerol, causing the marker properties of interstitial glycerol to become questionable. Consequently, the administration of glycerol, which is a frequent constituent of various infusions and emulsions, could promote secondary brain damage by adversely shifting osmotic gradients.

Chemical monitoring of neurosurgical intensive care patients using intracerebral microdialysis

The authors have used intracerebral microdialysis to develop a method for routine monitoring of disturbances in brain energy metabolism in patients in the neurosurgical intensive care unit. Microdialysis was conducted for periods ranging from 2.3 to 8.3 days in four patients (three with severe head injuries and one with severe subarachnoid hemorrhage). Altogether, 4447 chemical analyses from 587 dialysis samples were carried out. Concentrations of the energy-related metabolites lactate, pyruvate, and hypoxanthine were measured, and the lactate:pyruvate ratio was calculated. In addition, the acids glutamate, aspartate, taurine, glutamine, asparagine, and glycine were measured in one patient. The microdialysis data were matched with various clinical events, including intracranial hypertension and therapeutic interventions such as initiation or withdrawal of barbiturates and cerebrospinal fluid drainage. The present study shows that microdialysis can be used for long-term measurement of extracellular fluid (ECF) energy-related metabolites and amino acids in the frontal cortex of neurosurgical patients in a clinical setting. Fluctuations of the measured ECF energy-related substances corresponded to various clinical events presumably involving hypoxia/ischemia. The authors found a 25-fold increase in ECF glutamate, aspartate, and taurine under conditions of energy perturbation, as indicated by high levels of the lactate:pyruvate ratio, lactate, and hypoxanthine. The use of long-term intracerebral microdialysis in patients opens a new field of clinical research, with many possibilities for improving insight into intracranial dynamics in acute cerebral conditions.