title: Free and total catecholamines in critical illness.
abstract: The magnitude of circulating free and total (free plus conjugated) catecholamine responses to a strong and sustained stimulus was investigated in four groups of patients: traumatic brain injury (n = 24), vascular brain injury (n = 10), polysystem trauma (n = 7) and medical/surgical patients in an intensive care unit (n = 29). Despite significant three- to sevenfold elevations in both free and total norepinephrine (NE) and epinephrine (E), the ratio of free to total NE and E remained constant over a very broad range of values. The proportion of free E was twice normal (30.1-33.5 vs. 16.2%) in all but patients with polytrauma, whereas the percentage of free NE was unchanged in all patients (43.0%). All dopamine (DA) parameters remained generally normal. In the patients with traumatic or vascular brain injury, significant inverse correlations were present between the degree of neurological dysfunction, as indicated by the concomitant Glasgow coma score, and free NE, E, and DA and total NE and DA levels. Thus, during conditions of intense and prolonged catecholamine release, the proportion of free catecholamine remains constant and the total as well as free catecholamine concentration is proportional to the Glasgow coma score.
authors.affiliation: Department of Medicine, University of Rochester, School of Medicine and Dentistry, New York 14642.
authors.forename: P D
authors.initials: PD
authors.lastname: Woolf
authors.forename: R W
authors.initials: RW
authors.lastname: Hamill
authors.forename: L A
authors.initials: LA
authors.lastname: Lee
authors.forename: J V
authors.initials: JV
authors.lastname: McDonald
mesh_terms: D003422:Critical Care; D004298:Dopamine / Q000097:blood*; D004837:Epinephrine / Q000097:blood*; D006801:Humans; D009638:Norepinephrine / Q000097:blood*
chemical_list: D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine