Fluid management in the critically ill.

Fluid therapy, which is provided to restore and maintain tissue perfusion, is part of routine management for almost all critically ill patients. However, because either too much or too little fluid can have a negative impact on patient outcomes, fluid administration must be titrated carefully for each patient. The "salvage, optimization, stabilization, de-escalation" (SOSD) mnemonic should be used as a general guide to fluid resuscitation, and fluid administration should be adapted according to the course of the disease. In the initial salvage phase, lifesaving fluid should be administered generously. Once hemodynamic monitoring is available, fluid administration should be optimized by determining the patient's fluid status and the need for further fluid. This determination can be difficult, however; clinical indicators of hypovolemia, such as heart rate, blood pressure, and urine output, may not detect early hypovolemia, and edema is a late sign of fluid overload. Dynamic tests of fluid responsiveness such as pulse pressure or stroke volume variation can be used in only a small percentage of critically ill patients, and thus a fluid challenge technique is most frequently used to assess ongoing fluid requirements. Once a patient has been stabilized, efforts should start to concentrate on removing excess fluid. Which fluid should be used remains a matter of some debate. Crystalloid solutions are cheaper than colloid solutions, but colloid solutions remain in the intravascular space for a longer period, making edema less likely. Thus crystalloids and colloids should be used together, especially in patients likely to require large fluid volumes. Human albumin is a natural colloid and may have beneficial effects in patients with sepsis in addition to its volume effects. Fluids should be prescribed as are other medications, taking into account individual patient factors, disease processes, and other treatments.