Invited commentary: Hemorrhage and surgery cause a contraction of the extra cellular space needing replacement – evidence and implications

Because of its poor eyesight, the African land snail, Achatina fulica, cannot see what is ahead. During any journey, the snail proceeds by conducting a series of experiments upon its immediate environment, the results of which determine how the snail will proceed. The snail secretes a glistening mucous from storage sites adjacent to its ventral contact surface that reduces friction and makes the journey easier. The mucous is toxic to the snail’s enemies but leaves a visible trail so that any observer may know the course the snail has taken. The learning process of medical science is analogous in that the rate and direction of scientific progress cannot be predicted with certainty in real time, but the medical literature leaves a trail that offers the opportunity for scientists to re-analyze concepts and refine the learning process. Brandstrup and colleagues have made an important contribution to our understanding of the concept of “third space loss.” They conducted an exhaustive analysis of the radioisotope tracer methodology that produced early experimental data attempting to clarify the time course and quantify the magnitude of third space losses associated with shock and certain operations. They have concluded that flawed radioisotope tracer methodology, as used in the experiments supporting a contraction of the extracellular fluid space as a consequence of hemorrhage and surgery, has resulted in the adoption of a clinical mind set that has produced systematic overdosing of patients with intravenous electrolyte solutions during and after operations. They question whether some complications seen after injury during and after the Viet Nam war resulted from overuse of intravenous electrolyte solutions. They have noted, finally, that recent experimental studies and elegant trials of perioperative intravenous fluid therapy strategies have disclosed reduced complication rates when lower volumes of fluids are infused. ^{,  ,}