Plasma Volume Expander
Action And Clinical Pharmacology: The biological properties of dextrans are functions of molecular structure, average molecular weight and molecular weight distribution. For Rheomacrodex these have been selected so that the preparation exerts both a general and a microcirculatory flow improving effect, at the same time producing a rapid increase in plasma volume. Following the infusion of Rheomacrodex, approximately 60% of the dextran is excreted through normally functioning kidneys within 6 hours, and about 70% within 24 hours. The remainder is broken down in the body by endogenous dextranases.
Rheomacrodex possesses thromboprophylactic properties.
The usual blood-grouping, simple cross-matching and indirect Coombs’ test are not affected by a preceding infusion of Rheomacrodex. The only techniques interfered with are those in which enzymes are used.
Indications And Clinical Uses: Reduced capillary circulation as in shock, burns, fat embolism, pancreatitis, peritonitis and paralytic ileus.
Disturbances of arterial and venous circulation as in imminent gangrene, leg ulcer, Raynaud’s disease, nonhemorrhagical cerebral insults, etc.
Prophylaxis of postoperative and post-traumatic thromboembolism.
In vascular and plastic surgery, to improve local circulation and to reduce the tendency to thrombosis in transplants.
In open heart surgery, as an additive to the perfusion fluid in the heart lung machine.
Contra-Indications: Marked hemorrhagic tendency, as in thrombocytopenia. Oliguria or anuria in manifest renal disease. Pronounced heart failure. Known hypersensitivity to dextran.
Manufacturers’ Warnings In Clinical States: Pregnancy: Although anaphylactic reactions to Rheomacrodex are rare, the product should only be used during pregnancy when strictly indicated since anaphylactic reactions in the mother have been reported to cause anoxic brain damage with or without death of the fetus.
Precautions: Rheomacrodex is a hyper-colloid-osmotic solution and the risk of circulatory overload must therefore be constantly borne in mind, particularly in the presence of latent or manifest heart failure. Where infusion is rapid, the increase in plasma volume may temporarily be as much as twice the volume of liquid infused, since every gram of dextran circulating retains 20 to 25 mL water. The total dose and the rate of infusion are adjusted according to the clinical state of the patient, and are followed where necessary by observations of the arterial blood pressure and the central venous pressure. If Rheomacrodex is administered to dehydrated patients, the electrolyte and water balance should be corrected with crystalloid solutions. If, in the course of treatment with Rheomacrodex, there is the appearance of oliguria with viscous, syrupy urine, diuresis should be promoted by the administration of crystalloid solutions. If, in spite of this, the oliguria persists, a diuretic, such as furosemide or mannitol, should be given.
Adverse Reactions: Hypersensitivity reactions may occur. Symptomatology varies from mild reactions with flushing, urticaria and chills to more serious reactions involving hypotension and circulatory collapse. Such reactions are generally reversible, though fatalities have been reported in elderly patients and others with depressed cardiovascular function. The incidence of reactions is lower after trauma and during surgery. The increased secretion of corticosteroids under such conditions may provide a degree of protection. Thus, in the prophylaxis of shock or thrombosis in connection with surgery, infusion should not be started until the induction of anesthesia or surgical intervention has commenced. Treatment in shock or after trauma, however, is instituted as soon as possible.
Reactions are generally limited to the first few minutes of the first infusion of dextran, when the patient should be closely observed with facilities at hand for emergency treatment. If complications occur, the infusion should be discontinued and symptomatic treatment as for allergic reactions instituted (adrenaline, corticosteroids, antihistamines, etc.). In circulatory collapse, rapid volume substitution with some other infusion solution should be instituted.
Capillary oozing, which may arise from wound surfaces, is principal evidence of an increase in perfusion pressure and improvement in capillary flow.
Dosage And Administration: The dosage is calculated individually, and is adjusted for each case depending on its clinical course. The rate of infusion should be slow where there is a risk of overloading the circulation (see Precautions).
Reduced capillary circulation in shock, etc.: Initially, 500 to 1 000 mL (10 to 20 mL/kg) is given i.v., depending on other treatment also being given. Thereafter, 500 mL (approximately 10 mL/kg) is infused during the same 24 hours. This second dose can be repeated daily for a maximum of 5 days.
Disturbances of arterial and venous circulation: Initially, 500 to 1 000 mL (10 to 20 mL/kg) is given in the first 24 hours. In addition, 500 mL is given on the following day and every alternate day thereafter up to a maximum of 2 weeks.
Prophylaxis of postoperative and post-traumatic thromboembolism: 500 to 1 000 mL (10 to 20 mL/kg) is infused i.v. To minimize the risk of complications, the infusion should begin during surgery or as soon as possible after trauma. Treatment may be supplemented with a further 500 mL on the following day.
In cases at high risk of thrombosis (fracture of the neck of the femur, malignant disease of abdomen or prostate, prolonged immobilization, a history of previous thromboses, etc.) treatment is begun as above with 500 to 1 000 mL. On the following day and on every alternate day thereafter for a maximum of 2 weeks, a further 500 mL is given.
In vascular and plastic surgery: 500 mL (approximately 10 mL/kg) is given i.v. during the operation. A further 500 mL is given postoperatively. 500 mL is given on the following day and every alternate day thereafter up to a maximum of 2 weeks.
In open heart vascular surgery: 10 to 20 mL/kg Rheomacrodex is added to the perfusion fluid. The dextran concentration in the perfusion fluid must not, however, exceed 3%. The postoperative dosage is the same as that recommended for reduced capillary circulation.
Rheomacrodex 10% in dextrose should be used in cases of reduced renal capacity for excretion of sodium chloride or when restricted administration of sodium chloride is indicated (to decrease the supply of electrolytes when large volumes of fluid are required).
Administration: Since globulin precipitation and spontaneous red cell aggregation may occur when mixing bottled blood with electolyte-free sugar solution, Rheomacrodex 10% in dextrose should not be given through the same apparatus as blood. This does not apply to Rheomacrodex 10% in saline.
Availability And Storage: Rheomacrodex 10% in normal saline: Each L contains: dextran 40 Pharmacia Standard 2.5 mmol, sodium 150 mmol, chloride 150 mmol and water for injection q.s. Bottles of 500 mL.
Rheomacrodex 10% in dextrose: Each L contains: dextran 40 Pharmacia Standard 2.5 mmol, D-glucose USP 250 mmol and water for injection q.s. Energy: 720 kJ. Bottles of 500 mL.
Both forms are isotonic with blood. Dextran 40 has a certain tendency to crystallize when subjected to variations in temperature or when stored for a long time at high room temperature. Therefore store at a constant temperature, not exceeding 30°C. Keep from cold during transport.
RHEOMACRODEX® Medisan Pharmaceuticals Dextran 40 Plasma Volume Expander