Hemorrhage and operation cause a contraction of the extracellular space needing replacement--evidence and implications? A systematic review.
BACKGROUND
Hemorrhagic hypotension or operative trauma is believed to cause a contraction of the extracellular fluid volume (ECV) beyond the measured fluid losses. The aim of this review was to explore the evidence and implications of ECV loss.


METHODS
We performed a systematic review of original trials measuring ECV changes during hemorrhage or operation. PubMed, relevant periodicals, and reference lists were searched until no further original articles appeared. The quality of both the scientific and the technical methods of the trials were evaluated.


RESULTS
A total of 61 original articles were found. The pattern appeared that all investigators reporting shock or operation to cause a disparate reduction of the ECV had measured the ECV with the same method. The ECV was calculated from very few blood samples that were withdrawn after 20 to 30 minutes of equilibration of a tracer (the (35)SO(4)-tracer). Trials calculating ECV from multiple blood samples, after longer equilibration times, or using other tracers did not find a contraction of the ECV. On the contrary, trials using a bromide tracer found the ECV to be expanded after operation.


CONCLUSIONS
The evidence supporting the idea that hemorrhage or operation cause a contraction of the ECV is weak, and probably a result of flawed methodology.
Brandstrup
Birgitte
B
Department of Surgery P, Slagelse University Hospital, Ingemannsvej 18, DK-4200 Slagelse, Denmark. bbrandstrup@hotmail.com
Svensen
Christer
C
Engquist
Allan
A
D002986:Clinical Trials as Topic; D019317:Evidence-Based Medicine; D045604:Extracellular Fluid / Q000502:physiology*; D005440:Fluid Therapy; D006470:Hemorrhage / Q000150:complications*; D006801:Humans; D007022:Hypotension / Q000150:complications; D007432:Intraoperative Period; D012771:Shock, Hemorrhagic