Abstract:
Aim:
The aim of the study was to determine whether post-operative
autologous salvage system affects post-operative haemoglobin (Hb)
levels and reduces the need for homologous blood transfusion (HBT).
Methods: A prospective study of 211 patients who had
undergone unilateral primary THR with their preoperative,
post-operative Hb levels and requirement of homologous banked
blood recorded. Cell Saver 5 was used post-operatively for
autologous blood transfusion.
Results: A total 211 patients with mean age of 70 years was
enrolled to the study and complete data were obtained
perioperatively. The mean pre-operative and post-operative Hb
levels were 137.1g/L and 105.1g/L, respectively. Twenty-four
units of homologous red blood were transfused to twelve (5.4%)
patients, with a mean of 0.109 units per case. There were 65
patients (29.4%) older than 75 years, with 9 patients having
pre-operative Hb less than 120 g/L. Patients older than 75 years
were associated with a greater use of homologous blood with
those equal or under the age of 75 years (chi-squared test, p =
0.001). Mean of in-hospital stay was 6 days. No
transfusion-related and wound-related complications were
reported.
Discussion: Primary THR can be safely performed without
requiring HBT in patients without pre-existing haematological
disorder using autologous retransfusion system. This study has
shown that use of an autologous retransfusion system for primary
THR reduces the necessity for HBT. Post-operative blood salvage
also results in lesser patients dropping their post-operative Hb
level below 9.0 g/L (15.8%).
J.Orthopaedics 2009;6(1)e10
Keywords:
arthroplasty; total hip replacement;
autologous blood transfusion; homologous blood transfusion
Introduction:
Approximately
10% of red blood cell transfusion was used for orthopaedic
surgery1, such as spinal, total joint arthroplasty
and revision orthopaedic operations. At present, there is no
sound evidence on when to transfuse red cells and how much units
of homologous blood to give. Furthermore, no significant
measurable evidence was available for the differences in
practice that might have on the clinical outcomes. In spite of
the protocols and guidelines for red blood cell transfusion,
studies have shown that homologous red cell blood transfusion
can be as high as 30-57% following THR with mean volume of
transfused red blood cell being 1.5 units2 per
case.
Homologous
blood transfusion (HBT) in hospital is not without risk, even in
developed countries. Despites tight regulation and standards,
complications from clerical errors, transmission of blood-borne
infections, transfusion related acute lung injury (TRALI),
transfusion relation allergic reaction and immuno-suppression
remain3. The incidence of hepatitis B and
hepatitis C per unit of blood is estimated at 1 in 220,000 and 1
in 1,600,000, respectively, and the risk for Human
Immunodeficiency Virus (HIV) transmission is 1 per 1, 800, 000 4.
Risks
of transfusion-transmitted disease, such as HIV and hepatitis,
can be avoided with the use of autologous blood salvage system
perioperatively. Other major risks associated with HBT which
include acute haemolytic transfusion reaction, transfusion
related allergic reaction, leukocyte, platelet, or red cell
alloimmunization, and graft versus host reaction, can also be
eliminated. Although some have noted adverse reactions involving
fever, chills and tarchycardia in as many as 10 per cent of all
patient5, no clinical sequelae, such as coagulopathy,
electrolyte imbalance, renal insufficiency and abnormalities of
oxygen exchange have been recognized.
Conclusive
information in relation to the reduction of the rate of HBT with
the use of Autologous blood transfusion (ABT) device in primary
hip replacement was not available from previous studies because
of the design of the study; some included primary and revision
cases, others included hip and knee replacement, preoperative
autologous blood donation (PABD) or intra-operative salvage was
also made available in addition to the ABT device6-8.
Preoperative
donation is not available and intra-operative salvage is not
implemented as yet in our unit. Our unit already had a well
established autologous blood transfusion programme in place for
hip, major spinal and knee operations. Hence, we undertook a
prospective study to determine whether post-operative autologous
blood transfusion system affects post operative Hb levels and
reduces the need for HBT in elective unilateral primary THR. In
this study, we used Cell Saver 5 autologous blood retransfusion
system (Haemonetics Corp., Braintree, MA, USA).
The
purpose of this study is to investigate whether the retrieval
and reinfusion of postoperative blood salvage in the recovery
room for the patients who had elective unilateral THR reduce the
rate of HBT. This is a cost-neutral study in view of the higher
costs of the retransfusion system normally offset by savings in
homologous transfusion expense.
Materials
and Methods:
Patient
population
Patients who were undergoing unilateral primary THR for
osteoarthritis on a non emergency basis were eligible for this
prospective study. Eligibility criteria for the study were shown
in Table 1.
Inclusion
Criteria
|
Exclusion
Criteria
|
Elective,
unilateral primary hip operation
|
Emergency
or bilateral or revision hip operation
|
Age over 18
years of age
|
Blood mixed
with malignant cells; cancer in the wound area
|
|
Sickle cell
disease or sickle cell trait
|
|
Systemic
infection
|
|
Patients
with an infected prosthesis or wound; surgical field
contaminated by bacteria and contained topical haemostatic
agents, antibacterial, wound irrigants, fat or amniotic
fluids
|
|
Coagulation
disorder
|
|
Jehovah’s
witnesses
|
|
Unusual
auto-antibodies
|
|
Pregnancy
|
|
Patients
with an infected prosthesis or wound
|
Table
1: Eligibility criteria for the study
Perioperative
management
At pre-operative assessment, all patients are provided with
written formal consent and standard patient information for THR.
They will be admitted the day before the operation and the
pre-operative Hb level recorded. General anaesthesia was
administered to all patients and modified posterior approach was
used in the unilateral primary THR. A dose of 1.5g of cefuroxime
was given routinely at induction and two further doses of
cefuroxime (750 mg) at eight-hour intervals as per local
prophylactic antibiotics guidelines unless contraindicated.
Predeposited
autologous blood or intraoperative blood salvage was not used.
All drains were inserted during closure of the wound and then
connected to the Cell Saver in the operating room and remained
connected in the recovery room. Blood collected in the recovery
room was then processed and transfused back to the patient.
Adverse effects associated with the use of cell salvage device
were recorded. Any significantly serious adverse events will be
reported to the hospital transfusion committee and to any
appropriate national reporting system.
The
modified posterior surgical approach was used for the entire
cohort. The capsule and short external rotators are taken in a
single continuous layer off the posterior aspect of the greater
trochanter preserving the gluteus medius muscle. Then, the
capsule is repaired without repairing the piriformis tendon.
The
primary hip replacements were performed with an uncemented
acetabular cup component and a femoral component (either
cemented or uncemented). All acetabular components were
fixed with bone screws. The replacements for the uncemented
acetabular component were made using either Trilogy (Zimmer) or
Pinnacle (Depuy). The prostheses for femoral component were
either cemented C Stem (Depuy) or uncemented Corail (Depuy).
Recruited
patients were given identical routine postoperative care. All
patients received prophylactic dose 2500mg Fragmin® (dalteparin
– low molecular weight heparin) on the evening of surgery
until they are fully mobilised or until they were discharged
home. Thrombo-embolic deterrent stockings (TED stockings) were
used until six weeks following the operation. They were
mobilised since the first day following the operation - assisted
to stand on the first day and then progressed to walking with a
frame on the following day.
Local
blood transfusion practice was to give one or two units of
homologous blood if the post-operative Hb was less than 80 g/L
or if patients were symptomatic with Hb in the range of 80 g/L
to 100 g/L such as hypotensive, tarchcardia, syncope, dizzyness
or postural drop. All were monitored for post-operative pyrexia,
and wound or other complications. Transfusion related reaction
or complications were monitored and recorded as per local
practice. Post-operatively, the Hb levels and the number of
homologous units required were recorded for each patient. The
patients attended outpatient clinic for follow-up at six to
eight weeks. All relevant data were recorded separately and
completed for each case.
Ethical
Approval
ABT device had been used routinely for complicated orthopaedic
procedures such as spine operation, total joint replacements and
revision of total joint replacement. This blood salvage device
had also been used in the some occasions of elective primary
total hip replacement based on the individual preference of
Consultant Orthopaedic Surgeon. Local Research Ethical Committee
(LREC) approval is not required for this study as autologous
transfusion system had been used as part of the clinical care
for elective primary THR at the individual’s discretion. This
study examined the excellence of the service provided in Trauma
and Orthopaedic Unit with the use of postoperative autologous
blood transfusion system in relation to the usage of homologous
blood units from blood bank.
Formal
consent Specific consent for autologous transfusion procedures
carried out in theatre and recovery room is considered to be
necessary as ABT device will be used as a routine procedure in
this study under the named consultant. The usage of ABT device
in the operative procedure will be discussed during the process
of obtaining informed consent. The benefits and risks associated
with the ABT device will be verbally explained to patients and
documented in the consent form. All patients must be given full
information about the proposed treatment. General information
sheet with regards to the THR was given to the patients prior to
the operative procedure. The ABT device was not used by all of
the Consultant Orthopaedic Surgeons in their routine practice,
additional informed consent for use of ABT device in the study
was deemed vital and essential from the ethical point of
view.
End
points
The primary end point was the proportion of patients had HBT
following unilateral primary hip replacement. Blood bank
electronic records were used to examine the accuracy of the
number of unit of transfused blood used for each case.
Secondary
end point was the adverse effects associated with autologous
blood transfusion following the postoperative use of Cell Saver
5 as per local transfusion practice. The following clinical
events were recorded: fever (>38 degree Celsius),
tarchycardia, transfusion related allergic reaction and
hypotension.
Statistical
analysis
The relationship between HBT requirements and categorical
variables was examined using the chi-squared test. Comparisons
between groups were performed with the student’s t-test for
parametric data to establish their relationship with the need
for postoperative HBT. Significance was established at p <
0.05. Results were expressed as mean +/- standard deviation
(SD), unless stated otherwise.
Results:
Patient
population
From 1st July 2005, patients undergoing elective unilateral
primary THR for osteoarthritis under the care a single
consultant orthopaedic surgeon were eligible and then recruited
in this prospective study. Between July 2005 and August 2007,
221 consecutive patients were enrolled at University Hospital of
North Staffordshire and their data were completely obtained.
84
males and 137 females had unilateral primary THR operated by one
surgeon. The primary THR operations were performed under general
anaesthesia through a modified posterior approach with patients
in the lateral position. Meticulous haemostasis was obtained
prior to wound closure. All drain tubes were placed to drain the
joint space deep to the tensor fascia lata. After closure of the
wound, the drainage tubes were then connected to the blood
salvage device in the operating room and remained connected in
the recovery room. Blood collected in the recovery room was then
processed and transfused back to the patient. None of the
patients who had a malignant lesion or an infection near the
site of the operative drain or a coagulation disorder were
treated with Cell Saver 5. Their demographics, site of
operations and types of anaesthetic were summarized in Table
2.
Demographic
|
Without HBT
(n=209)
|
With HBT
(n=12)
|
Total
(n=221)
|
Male: Female ratio
|
79:130
|
5:7
|
84:137
|
Age (mean)
|
69 (range 42-90)
|
80 (range 68-91)
|
70 (range 42-91)
|
Orientation
|
|
|
|
Left: Right ratio
|
87:122
|
4:8
|
91:130
|
Diagnosis
|
|
|
|
Osteoarthritis
|
209
|
12
|
221
|
Type of anaesthetics
|
|
|
|
General anaesthetics
|
209
|
12
|
221
|
Table 2: Patient demographics, diagnosis and anaesthetic type
End
points
The Hb level averaged 105.1 g/L following postoperative
drainage tubes connecting to Cell Saver 5 for autologous blood
transfusion. The patients had an average preoperative hemoglobin
of 137.1 g/L (refer to Table 3). Eleven patients (4.98%) had a
post-operative Hb level below or equal to 80g/L. Twelve patients
(5.4%) were transfused with 24 units of homologous blood
postoperatively (refer to Table 4) with no clinical sequelae
secondary to HBT. Only three patients out of this group of
patients had postoperative Hb of more than 80g/L.
|
Without HBT
(n=209)
|
With HBT
(n=12)
|
p value
(student’s t-test)
|
Hb level (g/L)
(n=221)
|
Pre-operative Hb
|
138 (SD 12.7)
|
121 (SD8.81)
|
p<0.001
|
137 (SD 13.0)
|
Post-operative Hb
|
107 (SD 13.3)
|
76.3 (SD 8.27)
|
p<0.001
|
105 (SD 14.8)
|
Table 3: Pre-operative, post-operative and follow-up
haemoglobin (Hb) values (mean values and range)
Units
of homologous blood transfused
|
Post-operative
autologous blood transfusion (n=221)
|
Total
units
|
24
|
Units
per case (n=221)
|
0.109
|
Number
of patients received homologous blood transfusion (%)
|
12 (5.4%)
|
Male:
Female ratio
|
5:7
|
Table 4: Number of units of homologous blood
transfusion and number of patients transfused
There
were 65 patients (29.4%) older than 75 years, with nineteen
patients had pre-operative Hb less than 120 g/L. Patients older
than 75 years were associated with a greater use of homologous
blood with those equal or under the age of 75 years (chi square,
p<0.001). 67 patients had pre-operative haemoglobin of less
than 130g/L (Figure 3). Furthermore, patients with pre-operative
Hb level of less than 130g/L were associated with a increased
risks of using HBT with those more than 130g/L (chi square,
p<0.0001).
There
were no clinical symptoms, such as fever, hypotension,
tachycardia, and dizziness during the reparative period after
the operation with the use of Cell Saver 5. No complications
such as air or fat embolism, coagulopathy, renal failure, or
sepsis were recognized in any of the patients.
None
of the patients developed deep vein thrombosis or pulmonary
embolism with the provision of TED stocking and prophylactic
dose of low molecular weight heparin. The mean time for length
of in-hospital stay was 6 days (SD 3.8 days), with the range
between 2 – 36 days. No major deep wound complications were
recorded in patients enrolled in this study following the
provision of antibiotics prophylaxis.
Discussion
:
For
many years, PABD and intraoperative autotransfusion have become
well-established methods for major operations with anticipated
massive blood loss, in addition to avoid the risks associated
with HBT. Limitations such as storage problems, unexpected
delays in operation schedules and multiple preoperative visits
to hospital have restricted popularity of PABD in this country.
A large proportion of the patients undergoing total joint
arthroplasty were elderly and anaemic, and were unable to donate
sufficient quantities of blood to satisfy their operative
requirements. Furthermore, the cardiorespiratory consequences of
moderate postoperative anaemia may be significant in limiting
the mobility of patients after primary hip replacement. Such
patients may benefit from a prompt return of its preoperative Hb
level by using perioperative blood salvage methods. Blood
salvage system, either intraoperatively or postoperatively, is
not routinely used for primary hip replacement.
Comparison
with other studies was not available because some included
primary and revision cases as well as patients for whom PABD or
intra-operative salvage was made available. Studies that
involved primary cases, which included patients for whom PABD
and intra-operative salvage were available, have indicated that
post-operative salvage does not result in significant
haematological, transfusion or clinical benefit in uncomplicated
primary THR7-8. However, other study, which excluded
PABD and intra-operative salvage, concluded a reduction in
homologous transfusion in primary arthroplasty when
post-operative salvage is used6, 9. Our study
concluded the latter findings. The most important finding in our
study was a substantially reduction in the number of patients
requiring homologous transfusion. Twelve patients with
post-operative autologous blood transfusion (5.4%) required a
total of 24 units of HBT with a transfusion rate of 0.109 per
case. Our result is comparable with the recent study conducted
by Smith et al., a randomized study that demonstrated a
significant reduction transfusion rate in patients with
post-operative blood salvage (8%) as compared to those without
(21%), with 0.18 units of homologous blood per person in those
with post-operative blood salvage9. In the same
study, which excluded PABD and intra-operative salvage,
concluded a significantly higher percentage of patients in the
vacuum drain group required homologous blood transfusion compare
to those with post-operative blood salvage (21% compared to 8%)9.
Our study found 15.8% of the cohort had post-operative Hb less
than 90 g/L. Without the control, we are unable to demonstrate
the significance of this haematological benefit. However, this
study revealed the excellence of the service provided in Trauma
and Orthopaedic Unit with the use of postoperative autologous
blood transfusion system in relation to the usage of homologous
blood units from blood bank (0.109 unit of banked blood per
case).
Study
conducted by Smith et al. did not demonstrate significant
association of homologous transfusion with advanced age (> 75
years) or preoperative Hb below 130 g/L9. They claimed that this
may be a result of the relatively small number of patients in
this group. However, our study, which is comparable to their
study, demonstrate the significant association of HBT with
advanced age or preoperative Hb below 130 g/L, factors that have
been shown to increase the likelihood of homologous transfusion10.
In our group of patients who had HBT, all but one has
pre-operative Hb level more than 130g/L. Recent national audit
had recommended that preoperative anaemia should be corrected as
far as possible in order to minimize the likelihood of a patient
receiving a donor blood transfusion11. The chances of
requiring HBT following a hip arthroplasty increases as the
pre-operative Hb decreases resulting in a 90% risk of requiring
HBT when the pre-operative Hb is below 10.5 g/L10, 12.
Our unit had considered cross-matched bloods need to be made
available and the required units based on our study can be
reduced from two to one in patients undergoing primary THR, in
view of the higher HBT in patients with a preoperative Hb level
of less than 130 g/L. A group and save is then judged to be
adequate for patients with a pre-operative Hb level of more than
130 g/L.
The
inclusion of a group in which no drain was used may have
provided additional information in this study in relation to HBT.
Figures from one study showed a higher rate of homologous
transfusion for patients with drains (33% with drain versus
26.4% without drain) 13, whereas the other study
revealed homologous transfusion rate of 21% in those with a
vacuum drain9.
Post-operative
autologous salvage was not associated with an increased risk of
early complications. None of transfusion complications was
reported for patients with the post-operative autologous
salvage. With the high screening standards associated with
autologous banked blood, the association between HBT and
infection is controversial. Nevertheless, study reported a
reduction in transfusion related complications if autologous
transfusion is used and this is increased if homologous
transfusion is used14. Long-term follow-up of our
cases will continue to determine whether this is the case.
Post-operative
homologous blood transfusion is initiated when the serum Hb is
80g/L or lower, unless they are symptomatic as compared to the
70g/L as recommended by the British Committee for Standards in
Haematology (BCSH) guidelines15. Trigger serum Hb of 80g/L was
selected as most of patients in our centre are older patients as
indicated in this study (mean age 70 years). The Hb level is
monitored, and the blood pressure, pulse, and preoperative Hb
level are also monitored before HBT starts. Twelve patients had
HBT with a mean pre-HBT and post-HBT Hb level of 76.3g/L
(range=63-92g/L) and 99.3g/L (range 84-122g/L). Three patients
were transfused with post-operative Hb of more than 80g/L as
they were symptomatic (two with Hb of 80g/L and one with Hb of
85g/L. Only one patient had post-HBT Hb level of more than
120g/L (122g/L) which indicated that one unit of banked blood
could be avoided. These data suggest that our transfusion
practice for primary THR is closely followed current guidelines
for HBT. Patients whose pre-transfusion Hb was <79 should not
be transfused to achieve a ‘normal’ Hb concentration (i.e.
120 g/L). It is considered to be appropriate to use a one-unit
HBT to exceed the transfusion threshold of 80g/L.
The
effect of autologous salvage of blood in the recovery room on
the amount of blood that is transfused postoperatively is
unknown. The question cannot be answered by this prospective
study because a comparator group was not used, which is the
major limitation in our study. A historical, retrospective
control group would probably be inaccurate and inappropriate,
because HBT is now only given in patients who are symptomatic,
rather than routinely doing so in all patients whose Hb falls
below a certain value (which is relatively higher than the
current recommended trigger Hb level). No control group was
selected in the design of the study, as ABT device is not used
as part of the standard treatment for primary hip replacement.
Hence, inclusion of control group in this study inevitably
requires ethical approval. Jehovah’s Witnesses were excluded
for the same reason.
The
experience in our unit supports the feasibility of salvaging
blood, which would otherwise be discarded, from drainage tubes
as a practical method of autologous transfusion and conservation
of a precious resource for blood. We have planned to start to
use this device for all patients who have total joint
arthroplasty. The use of post-operative blood salvage techniques
in elective primary THR has the potential to reduce the use of
HBT and the risk for transfusion transmitted diseases by HBT. We
believed that the continued use of the Cell Saver
post-operatively would be both feasible and useful, bearing in
mind the risks of non-autologous blood transfusion and the
effectiveness of blood salvage device. This study confirmed the
feasibility and safety of transfusing autologous blood that was
salvaged post-operatively in the recovery room following THR.
This
study confirms that reduced unit per patients who had undergone
elective primary THR with post-operative salvage in a University
Hospital. We found the Cell Saver autologous re-transfusion
system easy to use and safe. The exact costs of HBT are hard to
quantify and varied from one region to the other region. Despite
this is a cost-neutral study with no added costs were incurred
by using the Cell Saver in the recovery room, the cost of banked
blood will undoubtedly continue to rise year on year because of
the requirement for the National Blood Service (NBS) to screen
blood products to ensure their safety. Increasing pressure is on
the additional screening for the detection of prion agents in
donor blood. Research is in progress to develop prion filter
technology and also to develop screening tests for prion agents.
In addition, with the declining usage of red cell year on year,
the cost of each unit provided is expected to rise to fund the
NBS. These considerations favour the continued use of autologous
retransfusion systems on economic grounds in our unit.
Acknowledgements:
I
gratefully acknowledge the participation of Philip Roberts and
Charles Baker in this study and the support of the clinical
staff in the Trauma and Orthopaedic Unit at University Hospital
of North Staffordshire NHS Trust for the data collection and
validation of clinical data.
Source
of funding:
No
benefits in any form have been received or will be received for
personal or professional use from a commercial party related
directly or indirectly to the subject of this article. No funds
were received in support of this study.
Disclosure:
No competing
interests declared.
Reference :
-
Stanworth
SJ et al. Which groups of patients are transfused? A study
of red cell usage in London and south east England. Vox
Sanguinis 2002; 83: 352-7.
-
Helm
AT, Karski MT, Parsons SJ, Sampath JS, Bale RS. A strategy
for reducing blood-transfusion requirements in elective
orthopaedic surgery: audit of an algorithm for arthroplasty
of the lower limb. J Bone Joint Surg [Br] 2003; 85-B: 484-9.
-
Hillyer
CD, Josephson CD, Blajchman MA, et al. Bacterial
contamination of blood components: risks, strategies, and
regulation: joint ASH and AABB educational session in
transfusion medicine. Haematology Am Soc Haematol Edu
Program 2003: 575-89.
-
Busch
MP, Kleinman SH, Nemo GJ. Current and emerging infectious
risks of blood transfusions. JAMA 2003; 289: 959-62.
-
Gannon
DM, Lombardi AV Jr, Mallory TIC et al. An evaluation of the
efficacy of postoperative blood salvage after total joint
arthroplasty: a prospective randomized trial. J Arthroplasty
1991; 6: 109
-
Grosvenor
D, Goyal V, Goodman S. Efficacy of postoperative blood
salvage following total hip arthroplasty in patients with
and without deposited autologous units. J Bone Joint Surg
[Am] 2000; 82-A: 951-4.
-
Rollo
VJ, Hozack WJ, Rothman RH, Chao W, Eng KO. Prospective
randomized evaluation of blood salvage techniques for
primary total hip arthroplasty. J Arthroplasty 1995; 10:
532-9.
-
Mauerhan
DR, Nussman D, Mokris JG, Beaver WB. Effect of postoperative
reinfusion systems on haemoglobin levels in primary total
hip and total knee arthroplasties. J Arthroplasty 1993; 8:
523-7.
-
Smith
LK, Williams DH, Langkamer VG. Post-operative blood salvage
with autologous retransfusion in primary total hip
replacement. J Bone Joint Surg [Br] 2007; 89-B: 1092-7.
-
Salido
JA, Marin LA, Gomez LA, Zorrilla P, Martinez C. Preoperative
haemoglobin levels and the need for transfusion after
prosthetic hip and knee surgery. J Bone Joint Surg [Am]
2002; 84-A: 216-20.
-
National
Comparative Audit of the use of blood in Primary, Elective,
Unilateral Total Hip Replacement. Report prepared by
National Comparative Audit of Blood Transfusion Use of blood
in Primary, Elective, Unilateral Total Hip Replacement
Project Group. July 2007.
-
Hatzidakis
AM, Mendlick RM, McKillip T, Reddy RL, Garvin KL.
Preoperative autologous donation for total joint
arthroplasty. An analysis of risk factors for allogenic
transfusion. J Bone Joint Surg 2000; 82-A (1): 89–100.
-
Walmsley
PJ, Kelly MB, Hill RMF, Brenkel I. A prospective randomised,
controlled trial of the use of drains in total hip
arthroplasty. J Bone Joint Surg [Br] 2005; 87-B: 1397-401.
-
Rosencher
N, Kerkkamp HEM, Macheras G, et al. Orthopaedic surgery
transfusion haemoglobin European overview (OSTHEO) study:
blood management in elective knee and hip arthroplasty in
Europe. Transfusion 2003; 43: 459-69.
-
Guidelines
for the clinical use of red cell transfusion. British
Journal of Haematology 2001; 113: 24-31.
|