Fluid therapy and newer blood products.
A fluid therapy plan for a patient is developed prior to surgery and is designed to meet each patient's needs. The volume and type of fluid are dependent on the patient's physical status; the acid-base, fluid, and electrolyte status; the surgical procedure; and the expected losses occurring during the procedure. No one fluid regimen is ideal for all patients. All fluid regimens must be continually re-evaluated. A brief minor surgical procedure in a healthy surgical candidate requires little or no fluid administration. In cases of more extensive surgical procedures involving invasion of the abdomen or chest as well as in cases with trauma and major blood loss, much more volume and a specific balanced replacement fluid are required. Depending on the severity of the surgical case, administration rates of 5 to 15 mL/kg/h or greater of crystalloid may be required to maintain perfusion. These rates are merely guidelines, and resuscitation should continue until the desired end point is reached. Balanced replacement fluids may be used to replace blood loss at a ratio of 3:1 and are added to maintenance and replacement requirements. Blood loss of 20% to 25% of the calculated blood volume or hematocrit values less than 20% are indications for colloids or blood replacement at a ratio of 1:1. The optimal fluid therapy regimen for a patient may involve a combination of crystalloids as well as natural and synthetic colloids, using each type of fluid to obtain and maintain perfusion and oxygenation to the tissues.