All fluid infusions are reduced to a minimum. After vigorous diuresis is induced (of the order of 500 ml/h) or comparable ultrafiltration rates are established, Pentaspan is infused to match fluid elimination (to maintain euvolemia). Hematocrit determinations (at least every 15 min) first remain steady and then start decreasing, suggesting an increase in circulating blood volume. As long as urine or ultrafiltration rates match the rate of infusion, the increase in circulating blood volume must reflect fluid mobilization. We generally allow for increases of the order of 20 per cent ( Fig.,2), which usually permit a decrease in inotropic and vasopressor support. At this point the colloid infusion is stopped. Conversely, if 2 to 2.5 liters of Pentaspan have been infused without any change in blood volume, the injury is assumed to be non-amenable to this treatment.
Fig. 2 (a) An example of changes in circulating blood volume achieved with colloid therapy. The colloid infusion is maintained until the circulating blood volume increases (loading phase). Thereafter, all fluid is restricted and fluid removal is continued until the circulating blood volume returns towards normal. Note how the circulating blood volume never becomes negative. (b) Summary of the fluid balance.
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