Transfusion for Massive Blood Loss
below is a description of massive blood loss and the inherent
problems associated with large volume blood transfusions. Following
this is a suggested protocol for guiding management of the patient
receiving a massive transfusion for haemorrhage.
Massive transfusion is arbitrarily definied
as the replacement of a patient's total blood volume in less than
24 hours, or as the acute administration of more than half the patient's
estimated blood volume per hour.
Aim of Treatment
Protocol for Management of Massive Transfusion
The aim of treatment is the rapid and
effective restoration of an adequate blood volume and to maintain
blood composition within safe limits with regard to haemostasis, oxygen
carrying capacity, oncotic pressure and biochemistry.
of Massive Transfusion
The complications of massive transfusion
are those of any blood transfusion plus :
- Blood Volume Replacement
The complications of massive transfusion are exacerbated by inadequate
or excessive transfusion. Traditionally transfusion of hypovolaemic
patients has been directed towards maintaining a haemoglobin concentration
of 10g/dl. The use of haemoglobin as the only indicator (or 'transfusion
trigger') may result in unnecessary administration of blood products,
with their concommittant risks.
Transfusion requirements should be based on the patient's
physiologic needs, defined by their oxygen demand (consumption).
Oxygen consumption is given by :
Where CO = Cardiac Output, CaO2 and CvO2 are arterial and
venous oxygen content respectively.
Oxygen delivery is :
The extraction ratio (ER) is the ratio of oxygen consumption
to oxygen delivery, normally around 25%.
The most appropriate monitor of tissue oxygen supply is the
tissue oxygen tension, reflected by the PvO2, or mixed venous
partial pressure of oxygen (normally 6 kPa, 45mmHg). Patients
with a low PvO2 can be classed as stable or unstable depending
on haemodynamics, ventilation, acid base status and urine output.
If they are stable, no therapy is indicated until a true critical
level is reached (PvO2 around 3 kPa, 23mmHg). If unstable, treatment
must be intituted.
Thus transfusion should be guided by haemodynamic stability,
PvO2 and ER. Obviously during trauma resuscitation, haemodynamic
stability is the key indicator.
In summary :
- If Hb > 10g/dl transfusion is rarely indicated.
- If Hb < 7g/dl transfusion is usually necessary.
- With Hbs between 7 and 10 g/dl, clinical status, PvO2 and
ER are helpful in defining transfusion requirements.
Dilutional thrombocytopenia is inevitable following massive transfusion
as platelet function declines to zero after only a few days of
storage. It has been shown that at least 1.5 times blood volume
must be replaced for this to become a clinical problem. However,
thrombocytopenia can occur following smaller transfusions if disseminated
intravascular coagulation (DIC) occurs or there is pre-existing
- Coagulation Factor Depletion
Stored blood contains all coagulation factors except V and VIII.
Production of these factos is increased by the stress response
to trauma. Therefore only mild changes in coagulation are due
to the transfusion per se, and supervening DIC is more likely
to be responsible for disordered haemostasis. DIC is a consequence
of delayed or inadequate resuscitation, and the usual explanation
for abnormal coagulation indices out of proportion to the volume
of blood transfused.
- Oxygen Affinity Changes
Massive transfusion of stored blood with high oxygen affinity
adversely affects oxygen delivery to the tissues. Evidence for
this is as yet not forthcoming, but it would seem wise to use
fairly fresh red cell transfusions (<1 week old). Use of fresh
(<24 hours) blood is not indicated. 2,3 DPG levels rise rapidly
following transfusion and normal oxygen affinity is usually restored
in a few hours.
Each unit of blood contains approximately 3g citrate, which binds
ionized calcium. The healthy adult liver will metabolise 3g citrate
every 5 minutes. Transfusion at rates higher than one unit every
five minutes or impaired liver function may thus lead to citrate
toxicity and hypocalcaemia. Hypocalcaemia does not have a clinically
apparent effect on coagulation, but patients may exhibit transient
tetany and hypotension. Calcium should only be given if there
is biochemical, clinical or electrocardiographic evidence of hypocalcaemia.
The plasma potassium concentration of stored blood increases during
storage and may be over 30mmol/l. Hyperkalaemia is generally not
a problem unless very large amounts of blood are given quickly.
On the contrary, hypokalaemia is more common as red cells begin
active metabolism and intracellular uptake of potassium restarts.
- Acid/Base Disturbances
Lactic acid levels in the blood pack give stored blood an acid
load of up to 30-40mmol/l. This, along with citric acid is usually
metabolised rapidly. Indeed, citrate is metabolised to bicarbonate,
and a profound metabolic alkalosis may ensue. The acid-base status
of the recipient is usually of more importance, final acid/base
status being dependent on tissue perfusion, rate of administration
amd citrate metabolism.
Hypothermia leads to reduction in citrate and lactate metabolism
(leading to hypocalcaemia and metabolic acidosis), increase in
affinity of haemoglobin for oxygen, impairment of red cell deformability,
platelet dysfunction and an increased tendency to cardiac dysrhythmias.
- Acute Respiratory Distress Syndrome (ARDS)
The aetiology of ARDS is as yet not fully understood, but various
risk factors have been identified. Both under- and over-transfusion
are associated with an increased risk of ARDS, as is albumin <
30g/l. Microaggregate filters should be used during massive transfusion
except when giving fresh whole blood or platelets.
Profound hypotension should be treated speedily. Administer crystalloid
or colloid infusions rather than delay fluid administration. Initial
red cell replacement is in the form of packed red cells.
At the start of resuscitation, blood should be taken for group and
crossmatch, coagulation tests, full blood count and biochemistry.
These must be properly labelled and identified in all situations.
Blood Bank Arrangements
Routine procedures should be followed until it becomes obvious that
massive transfusion is likely. The blood bank should be informed
as soon as possible that a major trauma is arriving or in the building.
For extreme emergencies group O blood should be supplied first.
Rhesus D negative blood should be supplied to all women of childbearing
age. Type specific (ABO Rh D matched) blood should be available
in 5 minutes and the switch should be made promptly so as not to
deplete stores of group O blood. Continue transfusing blood on this
basis until time is available to crossmatch on the original serum
sample. If an antibody screen is negative and more than one blood
volume has been administered there is no point attempting compatibility
tests except to exclude ABO mismatches.
During massive transfusion, regular monitoring of haemoglobin, platelet
count, prothrombin time (PT), partial thromboplastin time (PTT)
and fibrinogen levels should take place and be used to guide component
Component replacement should occur only in the presence of active
bleeding or if interventional procedures are to be undertaken.
For massive uncontrolled traumative haemorrhage, maintenance of full
haeostatic ability is usually unrealistic. The priority is for
definitive surgical arrest of haemorrhage from major vessels. Combinations
of stored whole blood, packed cells, colloids & crystalloids are given
to maintain blood volume or pressure at adequate levels and haemoglobin
at around 7g/dl or haematocrit at 0.25. Conserve limited supplies
of fresh blood, plasma or platelets until the bleeding is controlled.
- Platelet concentrates (1 pack/10kg) are given if platelet count
falls below 50. Each platelet concentrate also provides around
50ml of fresh plasma.
- Fresh frozen plasma (12ml/kg)is administered if PT or PTT are
running higher than 1.5 times control levels.
- Cryoprecipitate (1-1.5 packs/10kg) is given for Fibrinogen levels
When blood loss has lessened (0.5l/hour) and major vessels have
been controlled, it becomes worthwhile correcting haemostasis.
- M.D. Donaldson, M.J.Seaman, G.R. Park,
Massive Blood Transfusion, British Journal of Anaesthesia 1992;69:621-630
- Blood Transfusion Task Force - Transfusion
for Massive Blood Loss Clinical & Laboratory Haematology, 1988;10:265-273