Dextrans (Dextran 70 and Dextran 40) are macromolecular substances which are metabolized slowly; they may be used at the outset to expand and maintain blood volume in shock arising from conditions such as burns or septicemia. Plasma substitutes may be used as an immediate short - term measure to treat haemorrhage until blood is available.
They are rarely needed when shock is due to sodium and water depletion because, in these circumstances, the shock responds to water and electrolyte repletion. Plasma substitutes should not be used to maintain plasma volume in conditions such as burns or peritonitis where there is loss of plasma protein, water and electrolytes over periods of several days or weeks. In these situations, plasma or plasma protein fractions containing large amounts of albumin should be given.
Dextran 40 intravenous infusion is used in an attempt to improve peripheral blood flow in ischaemic disease of the limbs. Dextran 40 and 70 have also been used in the prophylaxis of thromboembolism but are now rarely used for this purpose.
Dextrans may interfere with blood group cross-matching or biochemical measurements and these should be carried out before infusion is begun.
Cautions: plasma substitutes should be used with caution in patients with cardiac disease or renal impairment; urine output should be monitored. Care should be taken to avoid haematocrit concentration from falling below 25 - 30% and the patient should be monitored for hypersensitivity reactions.
Side effects: Hypersensitivity reactions may occur including, rarely, severe anaphylactoid reaction. Transient increase in bleeding time may occur.
Dextran (Mw 40, 000)
Solution, 10% w/v in 5% Dextrose; 500ml
Indications: - conditions associated with peripheral local slowing of the blood flow; prophylaxis of post surgical thromboembolic disease
Cautions: -see notes above; can interfere with some laboratory tests (see also above); correct dehydration beforehand, give adequate fluids during therapy and, where possible, monitor central venous pressure; pregnancy.
Side effects: -see notes above
Dose and Administrations:
By intravenous infusion, initially 500 - 1000 ml; further doses are given according to the patient's condition (see notes above).
