Fluid management of patients undergoing abdominal surgery--more questions than answers

The 'wet vs. dry' philosophy in patients undergoing abdominal surgery is a subject of substantial debate. It has been suggested that restricting fluid input would significantly reduce complications and improve outcome following abdominal surgery. Keeping the patients dry may be a two-edged sword because the resulting hypovolaemia may result in compromised organ perfusion and poor tissue oxygenation. A review of the literature from 1990 to 2004 revealed that only very few studies on this subject have been published. Unfortunately, most of the 'dry'-supporting studies used fixed amounts of volume instead of a fluid concept adapted to the patients' need ('goal-directed') and there is no generally accepted definition of 'restricted', 'dry' or 'overload'. Not only the amount but also the kind of administered fluid appears to be important. Current evidence indicates that using crystalloids exclusively may cause overloading of the interstitial compartment with considerable negative sequelae, whereas using colloids may improve microperfusion and tissue oxygenation. This review shows that the meagre literature on a restricted volume replacement strategy in abdominal surgery patients cannot clearly support the 'dry' approach. Further well-performed studies are necessary to elucidate the ideal amount and type of fluid replacement and determine how to guide fluid therapy.