Paediatrics: Exchange transfusion

Exchange transfusion

Indications

•   Severe or rapidly rising hyperbilirubinaemia, e.g. due to severe rhesus or other haemolytic disease.

•   Cardiac failure secondary to severe anaemia (with normal or increased plasma volume), e.g. hydrops fetalis due to rhesus haemolytic disease.

•   Disseminated intravascular coagulation.

•   Polycythaemia with a venous haematocrit >70% and/or symptomatic.

•   Acute poisoning, including that due to metabolic disease.

Exchange is achieved by sequentially removing 10–15mL of blood from the child and then infusing warmed (37°), cross-matched, fresh (<72hr old), rhesus –ve, cytomegalovirus (CMV) –ve, irradiated or leucocyte fil-tered (to prevent graft vs. host disease), partially packed or whole blood. Exchange transfusion can be performed by either both withdrawing and then infusing blood via a single central venous catheter (e.g. umbilicus venous catheter), or withdrawing blood via a central catheter (arterial or venous) or peripheral arterial catheter and replacing it via a second central or peripheral venous catheter.

Blood volume (mL) to remove and then replace (i.e. exchange) is:

•   Severe anaemia with hydrops requires a single volume exchange, i.e. 80mL/kg body weight. Should be performed over a minimum of 1hr.

•   Removal of toxins, e.g. bilirubin or ammonia, requires a double volume exchange, i.e. 160mL/kg in newborns. This replaces 790% of total blood volume and should be performed over a minimum of 2hr.

•   To treat polycythaemia, a dilutional exchange transfusion is performed. The required exchange volume depends on the haematocrit (Hct) and can be calculated using the formula:

Volume = [measured Hct – desired Hct] x blood volume measured Hct

•   In a dilutional exchange replace blood with 0.9% saline 0.45% albumin.

Equipment

•   Venous and arterial catheters, either central or peripheral.

•   Two 20mL syringes and 3-way taps.

•   Blood administration set and warming coils.

•   Calibrated waste blood container.

•   +/– High flow rate infusion pump.

•   Appropriately cross-matched blood (see Indications).

•   ECG and BP monitor.

•   Sterile dressing pack (including gown, gauze swabs, drapes, and gloves).

Procedure

• If not already present, insert central or peripheral venous/arterial catheters.

• Start continuous ECG and frequent BP monitoring.

• As a baseline, measure serum FBC, U&E, Ca²⁺, glucose, and blood gases.

• Prime blood administration set and warm blood to 37°C.

• Arrange for an assistant to keep a constant accurate log of volumes removed and replaced throughout the procedure.

• Use a full aseptic technique throughout the procedure.

• Wash hands and put on sterile gloves, gown, +/– surgical mask.

• Connect 3-way taps into the system (exact arrangement depends on choice of method; see the following bullet points).

• If using a single central venous catheter, e.g. UVC, use two sequential 3-way taps to perform the following in order:

•   Withdraw 5–20mL blood from the baby using a syringe over a few minutes.

•   Turn first 3-way tap to allow blood to be syringed into a waste bag.

•   Turn second 3-way tap to allow 5–20mL, fresh, warmed blood to be drawn from pack.

•   Turn tap and syringe fresh blood slowly into baby (2–3min).

• If using two catheters together, remove 5–20mL aliquots of blood from the central or arterial catheter over 5–10min and then turn a single 3-way tap to allow blood to be pushed into the waste bag. Simultaneously, the same volume of fresh warmed blood is infused into the patient via the other venous catheter using a high rate flow infusion pump.

• A safe volume to remove each turn varies depending on size of infant. Remove 5mL aliquots for ELBW infants, increasing up to 20mL for full term infants.

• Apart from continuously monitoring pulse, ECG, BP, and temperature, every 30–60min during the procedure measure blood gases, FBC, U&E, serum Ca²⁺, and glucose. Measure again at the end of the procedure, as well as a coagulation profile. Correct any abnormality found.

• Once procedure is completed, leave catheters in place in case repeat exchange transfusion is required.

Complications of exchange transfusion

• Catheter-induced thrombotic or embolic phenomenon, e.g. portal vein thrombosis or NEC.

• Haemodynamic compromise, e.g. cardiac arrhythmia or hypotension.

• Metabolic, e.g. hypoglycaemia (transfused plasma often has a low blood glucose concentration due to red cell consumption), hypokalaemia, hypocalcaemia, hypomagnesaemia, acidaemia.

• Coagulopathy or thrombocytopenia.

• Hypothermia.

• Infection: bacteraemia, HIV, CMV, hepatitis B or C. Blood must be screened prior to transfusion.

• Graft vs. host disease: risk reduced by irradiation or leucocyte filtration.