Supportive therapy should include fluid resuscitation (to increase intravascular volume, increase venous pressure and venous return). Also some evidence exists that gas emboli may cause a relative hemoconcentration, which increases viscosity and impairs the already compromised circulation. Hypovolemia is less tolerated than relative anemia. In animal studies, moderate hemodilution to a hematocrit of 30% reduces neurologic damage. Crystalloids may cause cerebral edema; therefore, colloids are preferred for hemodilution