title: Haemostatic response to hypoxaemic/exercise stress: the dilemma of plasma volume correction.
abstract: OBJECTIVE
  Patients with arterial occlusive disease are typically hypoxaemic, and exercise is prescribed for rehabilitation. Both stressors independently contract plasma volume (PV), which may influence clinical interpretation of a patient's thrombogenicity. The aim of the study was to emphasise the conceptual significance of PV correction.
  
  
  RESULTS
  Venous plasma samples were obtained from 18 healthy men at rest in normoxia for the measurement of fibrinogen, prothrombin (PT), thrombin (TT) and activated partial thromboplastin (aPTT) times. Additional samples were obtained in hypoxia (12% oxygen) after 6 h of rest and immediately after a maximal exercise challenge. Haemostatic parameters were expressed before and after volume-shift correction. Passive hypoxia reduced PV by 3±5% (p<0.05 vs normoxia), with a further decrease observed during exercise (14±5%, p<0.05). The latter increased the absolute concentration of fibrinogen and shortened aPTT (p<0.05), but these changes were no longer apparent after PV correction (p>0.05). Likewise, the lack of change in absolute values for PT and TT (p>0.05) translated into an elongation after correction (p<0.05).
  
  
  CONCLUSIONS
  These findings highlight the important, but previously ignored, interpretive implications of PV correction when haemostasis is assessed.
authors.affiliation: Neurovascular Research Laboratory, Faculty of Health, Science and Sport, University of Glamorgan, Pontypridd, Mid Glamorgan, UK. lfall@glam.ac.uk
authors.forename: Lewis
authors.initials: L
authors.lastname: Fall
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Evans
authors.forename: Michael H
authors.initials: MH
authors.lastname: Lewis
authors.forename: Damian M
authors.initials: DM
authors.lastname: Bailey
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D010953:Plasma Volume / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen