Guidelines for Autologous Transfusion.

II. Acute Normovolaemic Haemodilution

Scientific Committee, Hong Kong Association of Blood Transfusion and Haematology Drafted by the Acute Haemodilution Working Group. Eudora Chow1 (Convenor), H.W. Liu2, Gregory Cheng3, Raymond Chu4, Tony Yan5

2.000 Acute Normovolaemic Haemodilution (ANH)
2.100 Introduction
2.110 ANH is designed to eliminate or reduce allogeneic transfusion. It entails the withdrawal of blood from a patient, either immediately before or shortly after induction of anaesthesia, and concomitant volume replacement by crystalloid and/or colloid to maintain normovolaemia. The blood removed is reinfused as indicated by intraoperative blood loss or at the conclusion of surgery.
2.120 The safety of ANH depends on the significant reserve normally available in the oxygen delivery system. Patients who are fit and not anaemic can have about one quarter of their blood volume withdrawn (not exceeding 20 ml/kg) if normovolaemia is maintained.
2.130 The benefits of ANH include
  1. Lowering the blood viscosity improves tissue perfusion and oxygenation.
  2. Reduces red cell loss at intraoperative haemorrhage.
  3. Provides fresh whole blood with coagulation factors and functional platelets.
  4. Reduces the need for allogeneic blood, thereby avoiding disease transmission and immune mediated reactions.
2.140 In contrast to preoperative blood deposit, ANH is simpler, less expensive and available to patients undergoing surgery at short notice.
2.200 Indication
ANH is suitable for
  1. Patients who can tolerate rapid withdrawal of one or several units of blood (not exceeding 20 ml/kg) before the period of blood loss.
  2. The expected blood loss should be no less than one litre or 20% of the estimated blood volume.
2.300 Patient's Eligibility
The physician performing the procedure, normally the attending anaesthetist, should determine the patient's suitability to undergo ANH. Patient should have near normal oxygen transport capacity, ideally he/she should be free from cardiovascular, respiratory and cerebrovascular diseases and has haemoglobin level of > 11 g/dl.
2.400 Exclusion Criteria
The technique is contraindicated when compensatory mechanism, an increase in cardiac output, is neither possible nor desirable. Conditions include:
  1. Haemoglobin < 11 g.dl.
  2. Ischaemic heart disease, critical stenotic heart valve disease, symptomatic aortic stenosis.
  3. Uncontrolled hypertension (BP systolic >180mmHg, diastolic >100mmHg) or hypotension. Patient on b-blockers or calcium channel blockers.
  4. Restrictive or obstructive lung disease.
  5. Impaired renal function and inability to handle large fluid volume.
  6. Coagulation disorders.
  7. Potential or active bacterial infection.
  8. Hypovolaemia.
21.500 Consent
Patient should give valid consent. It is important to explain the procedure, its associated merits, risks and the possibility of homologous transfusion.
2.600 Procedure
2.610 Protection against contamination
Blood should be withdrawn through an arterial or venous catheter under strict aseptic technique to provide maximum assurance of a sterile product.
2.620 Volume withdrawn
1.621 The amount of blood that can be withdrawn depends on many factors. It is primarily limited by a sufficient oxygen supply to the tissues, particularly to the heart. The age, medical fitness, preoperative Hct, intended post-haemodilution Hct and the kind of surgery must be considered.
1.622 The Gross1 formula helps to estimate the possible volume to be withdrawn.
Volume withdrawn = EBV x (Hct0 - Hct1)/Hctav
EBV = estimated blood volume
Hct0 = Hct before haemodilution
Hct1 = desired Hct after haemodilution
Hctav = average of the Hct before and after haemodilution
2.630 Volume replacement
It is crucial to maintain normovolaemia throughout the procedure. Crystalloid and/or colloid should be given simultaneously as blood is withdrawn.
2.640 Monitoring
There must be continual monitoring of haemodynamic variables throughout the procedure. This provides an objective assessment on how much blood can safely be removed.
2.650 Blood collection
The collection of blood should be directly supervised by the attending anaesthetist. Refer to appendix.
2.700 Labelling and Storage
2.710 Autologous blood must bear an easily recognisable label with the message "For Autologous Use Only" and contains information to enable correct donor identification. The patient's name, identification number, date and time of collection, sequential number (if more than one unit is removed), and the name and signature of the phlebotomist should be included. The label should have a suitable adhesive for regrigerated storage.
2.720 Keep the blood in the same operating room as the patient and maintain at room temperature to preserve platelet function. If it is anticipated that more than 6 hours will elapse before transfusion will take place, the blood should be refrigerated, ideally in a blood bank type refrigerator at 4 ± 2°C.
2.800 Blood Administration and Disposal
2.810 The anaesthetist shall be responsible for determining transfusion need. It is recommended to return the blood in reverse order so that the first unit with the highest haemocrit and platelets is administered last.
2.820 Blood kept at room temperature must be reinfused within 6 hours of collection. All unused blood after 24 hours must be properly discarded and documented.
2.900 Documentation
2.910 A written protocol describing the policies and procedure of ANH should be approved by the transfusion committee or its equivalent. The program should be supervised by a nominated staff whose responsibility should include compliance with procedure and their periodic review.
2.920 The anaesthetist must note on the anaesthesia record the amount of blood withdrawn, the amount and type of fluid infused, the amount of blood returned, along with the patient's vital signs.

We welcome comment to assist the review process. All correspondence regarding the guidelines should be addressed to: Scientific Committee, The Hong Kong Association of Blood Transfusion and Haematology. c/o Dr. HW Liu, 15 King's Park Rise, Yaumatei, KLN.


  1. Gross JB. Estimating allowable blood loss: corrected for dilution. Anaesthesiology 1983; 58:277-280.
  2. Stehling L and Zauder HL. Acute normovolaemic hemodilution. Transfusion 1991; 31:857-868.
  3. Gillon J., Thomas MJG and Desmond MJ. Acute Normovolaemic Haemodilution Transfusion 1996;36:640-643.

1Laboratory Haematologist, UCH
2Consultant Haematologist, HKRCBTS
3Senior Lecturer, Dept of Medicine, CUHK.
4Consultant Haematologist, PYNEH
5SMT, Service Development and Customer Relation, HKRCBTS