Biomaterial Database

Determinants of ammonia clearance by hemodialysis. 1996

J Cordoba, and A T Blei, and S Mujais

Department of Medicine, Lakeside Veterans Administration Medical Center, Chicago, IL 60611, USA.

Ammonia toxicity appears to contribute to the genesis of brain edema, a leading cause of death in fulminant hepatic failure. Because dialysis has been recommended for acute hyperammonemia in other conditions, we have conducted a study to analyze the determinants of ammonia clearance with the use of a single-pass dialyzer. We have used an ionic solution with a constant concentration of ammonia to estimate clearance at different blood flow rates, at dialysate flow rates, and with different dialyzer surfaces. Once hemodialysis had been optimized, we estimated ammonia, glutamine, and urea removal by using a single-compartment model. Our results show that the clearance of ammonia is blood flow dependent and is also influenced by dialysate flow rate and dialyzer surface. At clinically feasible conditions, ammonia can be extracted by more than 80% by setting the dialysate flow at a high rate. In addition to ammonia removal, hemodialysis allows the clearance of urea and glutamine, molecules that can be regarded as ammonia equivalents and that also undergo flow-dependent elimination.

UI	MeSH Term	Description	Entries
D001783	Blood Flow Velocity	A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.	Blood Flow Velocities,Flow Velocities, Blood,Flow Velocity, Blood,Velocities, Blood Flow,Velocity, Blood Flow
D001929	Brain Edema	Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries (see HYPOXIA, BRAIN). An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive HYDROCEPHALUS). (From Childs Nerv Syst 1992 Sep; 8(6):301-6)	Brain Swelling,Cerebral Edema,Cytotoxic Brain Edema,Intracranial Edema,Vasogenic Cerebral Edema,Cerebral Edema, Cytotoxic,Cerebral Edema, Vasogenic,Cytotoxic Cerebral Edema,Vasogenic Brain Edema,Brain Edema, Cytotoxic,Brain Edema, Vasogenic,Brain Swellings,Cerebral Edemas, Vasogenic,Edema, Brain,Edema, Cerebral,Edema, Cytotoxic Brain,Edema, Cytotoxic Cerebral,Edema, Intracranial,Edema, Vasogenic Brain,Edema, Vasogenic Cerebral,Swelling, Brain
D005973	Glutamine	A non-essential amino acid present abundantly throughout the body and is involved in many metabolic processes. It is synthesized from GLUTAMIC ACID and AMMONIA. It is the principal carrier of NITROGEN in the body and is an important energy source for many cells.	D-Glutamine,L-Glutamine,D Glutamine,L Glutamine
D006435	Renal Dialysis	Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.	Dialysis, Extracorporeal,Dialysis, Renal,Extracorporeal Dialysis,Hemodialysis,Dialyses, Extracorporeal,Dialyses, Renal,Extracorporeal Dialyses,Hemodialyses,Renal Dialyses
D006501	Hepatic Encephalopathy	A syndrome characterized by central nervous system dysfunction in association with LIVER FAILURE, including portal-systemic shunts. Clinical features include lethargy and CONFUSION (frequently progressing to COMA); ASTERIXIS; NYSTAGMUS, PATHOLOGIC; brisk oculovestibular reflexes; decorticate and decerebrate posturing; MUSCLE SPASTICITY; and bilateral extensor plantar reflexes (see REFLEX, BABINSKI). ELECTROENCEPHALOGRAPHY may demonstrate triphasic waves. (From Adams et al., Principles of Neurology, 6th ed, pp1117-20; Plum & Posner, Diagnosis of Stupor and Coma, 3rd ed, p222-5)	Encephalopathy, Hepatic,Portosystemic Encephalopathy,Encephalopathy, Hepatocerebral,Encephalopathy, Portal-Systemic,Encephalopathy, Portosystemic,Fulminant Hepatic Failure with Cerebral Edema,Hepatic Coma,Hepatic Stupor,Hepatocerebral Encephalopathy,Portal-Systemic Encephalopathy,Coma, Hepatic,Comas, Hepatic,Encephalopathies, Hepatic,Encephalopathies, Hepatocerebral,Encephalopathies, Portal-Systemic,Encephalopathies, Portosystemic,Encephalopathy, Portal Systemic,Hepatic Comas,Hepatic Encephalopathies,Hepatic Stupors,Hepatocerebral Encephalopathies,Portal Systemic Encephalopathy,Portal-Systemic Encephalopathies,Portosystemic Encephalopathies,Stupor, Hepatic,Stupors, Hepatic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000641	Ammonia	A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.
D014508	Urea	A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.	Basodexan,Carbamide,Carmol
D015314	Dialysis Solutions	Solutions prepared for exchange across a semipermeable membrane of solutes below a molecular size determined by the cutoff threshold of the membrane material.	Dialysate,Dialysis Solution,Dialyzate,Dialysates,Dialyzates,Solution, Dialysis,Solutions, Dialysis
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In