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Clinical strategies to avoid
blood transfusion
Learning objectives
After reading this article you should be able to:
C
describe how to optimize a patient’s haemoglobin preoperatively
C
explain the pivotal role of intraoperative anaesthesia
management including avoidance of hypothermia, optimal
positioning and use of cell salvage
C
discuss the evidence suggesting that a reduced transfusion
threshold of 8 g/dl is safe
Suzanne E Taylor
Michael H Cross
Abstract
Both transfusion and anaemia in the perioperative period are associated
with increased risk to the patient. With the advent of patient blood
management programmes, we are reminded that the clinical strategies
to avoid blood transfusion should be multidisciplinary, begin preoperatively and involve every stage of the patient pathway.
optimize the patient’s haemoglobin
minimize blood loss and bleeding
optimize the patient’s physiology to tolerate anaemia.
These strategies are multidisciplinary, multimodal and individualized and are being gradually introduced throughout Europe.
They can be divided into those used by the pre-operative
assessment clinic (POAC), those used intra-operatively either
by the anaesthetist, the surgeon or another member of the theatre
team and those used during the post-operative period.5
Keywords Blood; blood conservation; patient blood management;
pre-assessment; transfusion
Royal College of Anaesthetists CPD Matrix: 2A05.
Preoperative techniques to avoid transfusion (Table 2)
The decision to transfuse a patient during the perioperative
period should always be made on a case-by-case basis. There
is a balance of risk between anaemia and transfusion. Anaemia is
associated with increased risks of perioperative mortality and
morbidity, infectious complications, prolonged hospitalization
and a greater likelihood of transfusion. Traditionally, a haemoglobin measurement of 10 g/dl was considered to be an appropriate transfusion threshold, based on studies of rheology and
oxygen delivery, rather than outcome data. Current guidelines1
suggest it is safe to lower this threshold to 8 g/dl, even in
patients with cardiorespiratory disease.2 The risks of transfusion
are well understood and rare (Figure 1).
A total of 3038 events were reported to the UK Serious
Hazards of Transfusion (SHOT) in 2011.3 Table 1 below shows
the more common events of the 1815 analysed by SHOT.
There were no transfusion-transmitted infections reported to
the 2011 SHOT group with the risk now less than one in
a million. Reports of an association between long-term survival
following cardiac surgery and transfusion indicate that transfusion may have more risk associated with it than was previously
thought.4 Our understanding that risks are associated with both
anaemia and transfusion make it particularly important that we
use all possible clinical strategies available to avoid them.
POAC and multidisciplinary team (MDT) meetings
The role of the POAC is not only to investigate but also correct
any anaemia. Iron, vitamin B12 and folate deficiencies should all
be corrected before major elective surgery. Erythropoietin, used
in combination with iron, is successful in raising the haemoglobin concentration prior to surgery, thus reducing the need for
transfusion. Assessment of bleeding risk may favour temporarily
discontinuing oral anticoagulation (aspirin, clopidogrel etc.) but
the implications of this should be discussed at the POAC.
Preoperative autologous donation is a technique whereby the
patient undergoes weekly blood donations of up to 10 ml/kg. Iron
and erythropoietin are used to speed recovery of red cell mass
between donations, prior to surgery. However, the National Blood
Service in the UK does not offer this service as it is expensive, time
consuming, increases requirement for autologous blood transfusion and the risk of transfusion error is not reduced.
MDT meetings enable discussion about the correct approach
to surgery. This should include feasibility of minimally invasive
above open surgery (e.g. open aortic aneurysm repair vs. endovascular repair) or staging procedures (e.g. corrective spinal
surgery performed in two stages, allowing recovery from
anaemia in between). The decision to use a larger operating
team, thus reducing the duration of surgery, may also be taken.
Patient blood management (PBM)
Intraoperative strategies to avoid transfusion (Table 3)
PBM is the application of evidence-based medical and surgical
concepts designed to:
Suzanne E Taylor MB ChB MRCP FRCA is a Locum Consultant Anaesthetist
at Leeds General Infirmary, UK. Conflicts of interest: none declared.
Although some of the strategies used in the operating room are
the domain of the anaesthetist (e.g. controlled hypotension) and
some are specific to the surgeon (e.g. meticulous haemostasis),
there are several techniques where responsibility is less clear and
a team approach is important (e.g. the use of cell salvage).
Michael H Cross BSc MB ChB FRCA FFICM is a Consultant Cardiac Anaesthetist at Leeds General Infirmary, UK. Conflicts of interest: none
declared.
Patient positioning
Blood loss can be minimized with attention to positioning,
particularly when the patient is placed in the prone position.
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Percentage of events by category reported in the
Serious Hazards of Transfusion (SHOT) annual report
2008 (n = 1040)
Preoperative techniques to avoid transfusion
Multidisciplinary
team
IBCT (262)
ADE (137)
ATR (300)
TRALI (17)
HTR (55)
PTP (1)
TAGVH (0)
TTI (6)
HSE (139)
TACO (18)
TAD (1)
AT (28)
I&U (76)
Haematinics
Pharmacotherapy
Medication review
Other
Anaesthetist
Surgeon
Haematologist
Pharmacist
Iron
Vitamin B12
Folate
Erythropoietin
Appropriate withdrawal of antiplatelet/
anticoagulant medication
Preoperative autologous donation
(not available in UK)
Table 2
blood transfusion in hip, spinal and open prostate surgery.
Numerous pharmacological methods have been described
including neuroaxial blockade, inhalational anaesthetics,
intravenous b-blockers (esmolol), a-blockers (phentolamine),
calcium channel blockers (diltiazem) and direct arterial or
venous vasodilators (glyceryl trinitrate or sodium nitroprusside).
If controlled hypotension is employed, invasive arterial monitoring should be used as standard. Contraindications to this
technique include coronary artery disease, poorly controlled
hypertension, cerebrovascular disease and anaemia.
Figure 1
Pelvic and chest supports reduce pressure on and enhance flow
through the inferior vena cava, with less passing through the
vertebral venous plexuses. Bleeding is reduced in radical prostate
surgery using hyperextension of the back so that the legs and
heart are lower than the operative site.
Ventilation
Minimizing mean intrathoracic pressure during controlled
ventilation with minimal use of positive end-expiratory pressure
and low tidal volumes increases venous return, leading to
reduced blood loss.
Antifibrinolytic agents
Tranexamic acid is widely used to reduce bleeding in orthopaedic
and cardiac surgery. Aprotinin was licensed for patients undergoing cardiac surgery but the licence was suspended when
a study suggested that the risks of complications outweighed the
benefits of reduced bleeding. Following a review of the study and
other literature the European Medicines Agency has recently
(2012) recommended that the suspension be lifted.
Controlled hypotension
An accepted definition of controlled hypotension is a mean
arterial pressure (MAP) of 50 mmHg, based on estimates of
adequate cerebral perfusion pressure in the healthy population. It
was originally used as a technique to improve the operative field,
but evidence has emerged showing it leads to a reduced need for
Intraoperative strategies to avoid transfusion
Anaesthetic
Most common causes of reports to SHOT
Handling and storage
Incorrect blood component transfused
Inappropriate and unnecessary transfusion
Clinical
Acute transfusion reaction
Anti-D events
Haemolytic transfusion reaction
Pulmonary complications of transfusion
C
C
C
247
149
13.6%
8.2%
587
249
94
118
32.3%
13.7%
5.2%
6.5%
Surgical
Antifibrinolytics
Circulatory overload
Transfusion-associated dyspnoea
Transfusion-related acute lung injury
Haematological
Table 1
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Positioning
Ventilation (low PEEP and tidal volumes)
Controlled hypotension
Normothermia
Minimally invasive surgery/staged procedure
Extended surgical team
Surgical adhesives
Tissue sealants
Platelet gel
Tranexamic acid
E-aminocaproic acid
Aprotinin
Acute normovolaemic dilution
Cell salvage
Table 3
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allogenic blood transfused intra-operatively should be warmed
prior to transfusion, in keeping with the NICE guidance on
management of inadvertent perioperative hypothermia.6
Postoperative strategies to avoid transfusion
Management
Devices
Pharmacotherapy
Lower transfusion threshold
Avoiding hypothermia
Reinfusion drains
Iron, vitamin B12
Postoperative strategies to avoid transfusion (Table 4)
Reinfusion of blood from wound drains
Blood may be collected from wound drains before being treated
and reinfused. Treatment may be simple filtration prior to reinfusion which is commonly used in orthopaedics and is considered safe if the volume is less than a litre and the process is
completed in less than 6 hours. Some centres use centrifuged and
washed wound blood from mediastinal shed blood following
cardiac surgery, but this is a more complex procedure.
Table 4
Acute normovolaemic haemodilution
This technique involves withdrawing approximately 450 ml of
blood into a standard blood bag containing citrate, phosphate,
dextrose and adenine with simultaneous infusion of colloid to
maintain normovolaemia. This is usually repeated three times,
depending on the initial haematocrit. Reduction in need for blood
transfusion relies on the fact that there is reduced red cell loss
intra-operatively. The blood is then reinfused at the end of the
operation. This reinfusion should be supervised by the anaesthetist involved in the initial harvesting, as the usual checking
procedures for administering this blood are not applicable.
Transfusion threshold
The most significant factor in avoiding transfusion over the past
10 years is due to education of doctors that a reduced transfusion
threshold is safe. Recent evidence demonstrates that a liberal
transfusion strategy (a higher haemoglobin threshold of 10 g/dl)
did not improve outcomes compared to a restrictive strategy
(haemoglobin threshold of <8 g/dl) in a population of high-risk
patients.7
A
Cell salvage
This technique relies on a combination of a reservoir for collection
of aspirated, shed blood and a centrifugal system to wash and
concentrate the blood. Blood is anticoagulated as it is aspirated,
either with heparin or with a solution of acidecitrateedextrose.
With an adequate volume in the reservoir, the blood is then
centrifuged to concentrate the red cells and washed with normal
saline. The resulting product is concentrated red cells with no
clotting factors or platelets and a haematocrit of approximately
55%. Cell salvage is indicated for operations when the expected
blood loss is 20% or more of the estimated total blood volume or
when more than 10% of patients undergoing the procedure require
a transfusion. The list of contraindications to cell salvage is extensive and certainly includes the use of anything that will cause cell
lysis in the reservoir (sterile water, hydrogen peroxide, alcohol).
Many centres use cell salvage for obstetric and cancer surgery
because despite previous concerns, there is little evidence to
indicate that reinfusion of small amounts of amniotic fluid or
malignant cells is harmful.
REFERENCES
1 The Association of Anaesthetists of Great Britain and Ireland. Blood
transfusion and the anaesthetist: red cell transfusion 2.
2 Wahr JA. Myocardial ischaemia in anaemic patients. Br J Anaesth 1998;
81(suppl 1): 10e5.
3 Serious Hazards of Transfusion (SHOT), annual report 2011.
4 Surgenor SD, Kramer RS, Olmstead EM, et al. The association of perioperative red blood cell transfusions and decreased long-term
survival after cardiac surgery. Anaesth Analg 2009; 108: 1741e6.
5 Shander A, Van Aken, Colomina MJ, et al. Patient blood management
in Europe. Br J Anaesth 2012; 109: 55e68.
6 National Institute for Health and Clinical Excellence. Perioperative
hypothermia (inadvertent) (CG65).
7 Carson JL, Terrin ML, Noveck H, et al. Liberal or restrictive transfusion in
high-risk patients after hip surgery. N Engl J Med 2011; 365: 2453e62.
Avoidance of hypothermia
Hypothermia will render the patient hypocoagulable due to
effects on enzyme function within the coagulation cascade. Any
FURTHER READING
Spiess BD, Spence RK, Shander A. Perioperative transfusion medicine,
2nd edn, Lipincott Williams and Wilkins.
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