Cerebral Microdialysis in Neurocritically ill Patients
Ahmed Talaat Mohammady;
Abstract
Pathophysiology of cerebral ischemia and brain trauma indicates that similar mechanisms contribute to loss of cellular integrity and tissue damage. Mechanisms of cell damage include oxidative stress, excitotoxicity, apoptosis, free radical production and inflammation.
Ischemia causes metabolic stress and biochemical responses leading to alteration of concentration of interstitial fluid substances, most important and commonly assessed are glucose, glycerol, glutamate and lactate/pyruvate ratio.
Microdialysis is a technique for sampling the chemistry of the interstitial fluid of tissues and organs. It started as an animal research technique but has gradually been applied to man as well as animal.
A thin microdialysis catheter is introduced into brain tissue. The microdialysis catheter is either tunnelated under the scalp and introduced into the brain tissue through a burrhole \or directly through a bolt fixed to the skull in the usual manner. A microdialysis pump perfuses an artificial cerebrospinal fluid through the catheter; this fluid equilibrates with the interstitial tissue surrounding the catheter. The equilibration occurs by diffusion of chemicals over the dialysis membrane without the need to remove any fluid from the organ. Using a 10-mm dialysis membrane and a perfusion flow of 0.3 l/min the concentration of glucose, pyruvate, lactate and glutamate in the dialysate become approximately 70% of the concentration in the interstitial fluid. The samples are continuously collected into microvials which are analyzed at the bedside by a microdialysis analyzer commonly every hour or as needed. The analysis results are displayed as trend curves on the screen of the analyzer.
The in vivo microdialysis has been used to investigate many human CNS diseases as head trauma, neurodegenerative conditions and brain tumors and as well has been used extensively for monitoring ischemia in SAH and secondary vasospasm. Microdialysis is a technique which is suitable for both recovery and administration of minute concentrations, thus making it a useful method of both diagnostic and therapeutic application.
In vivo microdialysis has been applied in the administration of drugs in some cases such as epilepsy and neoplasia.
Ischemia causes metabolic stress and biochemical responses leading to alteration of concentration of interstitial fluid substances, most important and commonly assessed are glucose, glycerol, glutamate and lactate/pyruvate ratio.
Microdialysis is a technique for sampling the chemistry of the interstitial fluid of tissues and organs. It started as an animal research technique but has gradually been applied to man as well as animal.
A thin microdialysis catheter is introduced into brain tissue. The microdialysis catheter is either tunnelated under the scalp and introduced into the brain tissue through a burrhole \or directly through a bolt fixed to the skull in the usual manner. A microdialysis pump perfuses an artificial cerebrospinal fluid through the catheter; this fluid equilibrates with the interstitial tissue surrounding the catheter. The equilibration occurs by diffusion of chemicals over the dialysis membrane without the need to remove any fluid from the organ. Using a 10-mm dialysis membrane and a perfusion flow of 0.3 l/min the concentration of glucose, pyruvate, lactate and glutamate in the dialysate become approximately 70% of the concentration in the interstitial fluid. The samples are continuously collected into microvials which are analyzed at the bedside by a microdialysis analyzer commonly every hour or as needed. The analysis results are displayed as trend curves on the screen of the analyzer.
The in vivo microdialysis has been used to investigate many human CNS diseases as head trauma, neurodegenerative conditions and brain tumors and as well has been used extensively for monitoring ischemia in SAH and secondary vasospasm. Microdialysis is a technique which is suitable for both recovery and administration of minute concentrations, thus making it a useful method of both diagnostic and therapeutic application.
In vivo microdialysis has been applied in the administration of drugs in some cases such as epilepsy and neoplasia.
Other data
| Title | Cerebral Microdialysis in Neurocritically ill Patients | Other Titles | الميكرودياليسيس (الترشيح الدقيق) للمخ في مرضي الرعاية المركزة للمخ والاعصاب | Authors | Ahmed Talaat Mohammady | Issue Date | 2017 |
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