Do dilution effects confine interpretation and value of biochemical results in the early postinjury phase?

Background: In contrast to experimental hemorrhage, traumatized Patients (p ts) often receive a non-uniform but nevertheless aggressive volume therapy. Starting at the scene of accident, different amounts are infused mostly de pendent on the first impression of injury severity. The aim of this report was (i) to exactly determine primary volume resuscitation and (ii) evaluate its impact on the interpretation of biochemical plasma parameters followin g major trauma. Methods: In a prospective polytrauma study on 69 pts, the exact amount of i nfused fluids (colloids, crystalloids, blood and plasma products, liquid dr ugs) was assessed during the first 24 hours. Analyses were performed on the degree of trauma based on ISS (gr. I: < 9; gr. II: 9-17; gr. III: 18-30; g r. IV: > 32), on the injury pattern and surviving as well. Hematocrit and p lasma protein concentration (PP) were determined in parallel as early as at the scene of accident, at hospital admission, and every second hour therea fter. Results: The volumes administered varied between 0.5 and 48 liters and were related to the injury severity (gr. I/II < gr. III/IV; p=0.003) and surviv al (< nonsurvivors; p = 0.003) as well. Concomitantly, PP decreased signifi cantly (p < 0.05 in either case). There was a clear linear correlation betw een simultaneously measured PP and hematocrit (r(2) = 0.6585; n = 20; p < 0 .001). Conclusion: When interpreting the impact of biochemical variables following trauma, one strictly has to consider any major volume replacement during t he first 24 hours. Plasma protein-related data obviously reflect 'true' val ues independent of volume effects at least in the early postinjury period. Only by this, any comparison between different patients and even studies ap pear reliable.