The end of the crystalloid era? A new approach to peri-operative fluid administration.

The metabolic response to surgery causes sodium and water retention. It does not seem logical to pour crystalloid solutions into patients in the peri-operative period, particularly when these solutions can cause deterioration in lung function. Plasma volume must be maintained to prevent a decreased blood flow to vital organs such as the kidneys. Blood or colloid solutions, not crystalloid solutions, should be used for this purpose, since the latter are distributed throughout the whole extracellular space and are less effective in maintaining plasma volume. Water given as 5% dextrose should be given in minimal quantities to maintain intracellular hydration. Patients undergoing minor to moderate surgery when they are likely to be drinking within 24 hours do not usually require any intravenous infusion. Moreover, to administer intravenous fluids to these patients may cause harm. No fluid regimens should be inflexible and the patient's size, age and fluid losses should be taken into account.