Department of Anaesthesiology and Intensive Care, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh 160012, India
Corresponding author. E-mail: gdpuri@sancharnet.in
Accepted for publication: June 6, 2003
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. This prospective observational audit by a team of anaesthetists over 3 months in a multi-speciality tertiary care teaching hospital used strict preset criteria to evaluate the use of blood transfusion during elective surgery by anaesthetists. The criteria used to evaluate the rate of appropriate transfusion were haemoglobin less than 8 g dl1, haemoglobin less than 10 g dl1 in patients with medical co-morbidities and blood loss greater than 20% of blood volume when more than 1000 ml.
Results. The overall rate of appropriate use of blood was 40.7%; it was inappropriate in 19.2% of cases (haemoglobin >11 g dl1). The primary trigger was low haemoglobin (measured intraoperatively or derived from blood loss). Patients in whom haemoglobin was measured intraoperatively had a significantly higher appropriate use of blood (P<0.05). There was a reduction in blood use over the 3-month audit period (P<0.05).
Conclusions. Current intraoperative blood use is sub-optimal. Intraoperative haemoglobin estimation is an effective and simple measurement to improve appropriate use of blood. The indication for transfusion should be recorded in the case notes.
Br J Anaesth 2003; 91: 5869
Keywords: blood, transfusion; transfusion, appropriate
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Methods and results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Organization of audit programme
After obtaining Institute Ethics Committee approval, blood use in all elective non-cardiac surgical adult patients was assessed over a 3-month period. Apart from cardiac surgery, patients undergoing transplant and paediatric surgery were also excluded from the audit. The programme was started in August 2002 with a pilot study in the general surgery operating theatre.8 By September 2002, the audit programme had started in all 17 operating theatres. A consultant anaesthetist was designated as the programme coordinator and an audit team comprising two registrars and two residents was assigned to visit the operation theatres daily. The team was charged to collect the following data on each patient anaesthetized: physical characteristics of the patient, preoperative haemoglobin level, medical co-morbidities, units of blood cross-matched, indication for blood transfusion, total estimated blood loss, units of blood transfused, and the postoperative haemoglobin level. Each transfusion episode was assessed independently by an anaesthetist who was not involved in any decision regarding patient management. The evaluation consisted of searching the patients notes on the specific transfusion episode for evidence that satisfied one or more of the predetermined criteria for rating appropriate transfusions. The criteria used to evaluate the rate of appropriate transfusion were haemoglobin greater than 8 g dl1, haemoglobin greater than 10 g dl1 in patients with medical co-morbidities and blood loss greater than 20% of blood volume when more than 1000 ml. These criteria were derived from the literature,3 4 and recent ASA guidelines.5 Medical co-morbidities such as coronary artery disease, renal dysfunction, left ventricular dysfunction, and chronic obstructive airway disease were recorded. The indications for triggering blood transfusion were classified as low haemoglobin, hypovolaemia, and the anaesthetists or surgeons choice (blood transfused in spite of the absence of low haemoglobin or hypovolaemia, on the advice of the anaesthetist or surgeon responsible for the patient). Blood transfusion was considered inappropriate1 6 when the postoperative haemoglobin was above 11 g dl1.
Statistical analysis
2 test was used for comparing categorical variables and a P value of 0.05 or less was considered significant.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The primary trigger for transfusion was low haemoglobin (72.1%) followed by hypovolaemia (11.4%). In 16.5% of cases, blood was transfused despite the absence of any of these indications, on the advice of the anaesthetist or surgeon responsible for the patient (clinician choice).
Using the preset criteria, blood was used appropriately in only 40.7% of cases. Taking postoperative haemoglobin of above 11 g dl1 as inappropriate use of blood, 19.2% of transfusions were found to be unnecessary.
Intraoperative haemoglobin estimation was performed in 29 cases (20.7%). Appropriate use of blood occurred in 72.4% of these patients compared to 32.6% of patients in whom the intraoperative haemoglobin was determined from blood loss and preoperative haemoglobin (P<0.05, 2 test). In the patients in whom intraoperative haemoglobin was estimated, the inappropriate use of blood was low (10.3%).
Medical co-morbidities were found in 30 of the 140 patients transfused (21.4%). These patients had a significantly higher rate of appropriate transfusion of (80%) compared with the other patients (P<0.05, 2 test). It was observed that over the 3-month audit period, there was a gradual decrease in blood use (P<0.05) and an improvement in its appropriate use (Table 1).
|
![]() |
Comment |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Blood is transfused to increase oxygen content and improve oxygen delivery, thereby preventing tissue hypoxia. In the absence of clinically reliable direct measurements of adequate tissue oxygenation, haemoglobin concentration is commonly used as a surrogate.7 In the presence of adequate cardiorespiratory function, there is evidence that a haemoglobin concentration of 910 g dl1 improves capillary perfusion, reduces viscosity and improves tissue oxygenation.8 A haemoglobin level of 8 g dl1 seems an appropriate threshold for transfusion in surgical patients with no risk of ischaemia, whereas a threshold of 10 g dl1 can be justified for patients who have compromised cardiorespiratory function.4
Decisions regarding perioperative transfusion are often difficult and involve clinical judgement. The factors that influence an anaesthetists or surgeons decision to transfuse include the patients cardiopulmonary reserve, the rate and magnitude of the blood loss, oxygen consumption, and atherosclerotic disease (cerebrovascular, cardiovascular, peripheral, and renal).9 If an objective laboratory variable such as intraoperative haemoglobin concentration is added, then the decision to trigger transfusion can be justified. Intraoperative blood loss estimation is subjective and often unreliable, because of inaccuracies in measurement from drains and swabs, intercompartmental fluid shifts during surgery, and the dilutional effects of crystalloid therapy.5 This can result in an overestimation of blood loss, provoking an excessive response. In our audit, intraoperative haemoglobin estimation was made in only 20.7% of patients. Transfusions in these patients were often appropriate, with a low incidence of inappropriate use (10.3%).
The objective of blood transfusion, as specified by the ASA guidelines, is to improve inadequate oxygen delivery secondary to anaemia. In our audit, low haemoglobin was the primary trigger (72%). The other two common but inappropriate triggers were hypovolaemia and the anaesthetists or surgeons choice. The use of whole blood as a volume substitute, though inappropriate, is still being practised. The reason for this may be the availability of blood, and the belief that complications of transfusion occur infrequently and are usually benign. In this audit, 16.5% of transfusions were on the advice of the anaesthetist or surgeon responsible for the patient (clinician choice). This group of transfusions had a very high rate of inappropriate use (52%), according to our criteria.
The incidence of appropriate use of blood transfusion varies widely from 6099%, depending on the criteria used.6 10 This audit using strict criteria, showed a low rate of appropriate blood use (40.7%). The main reason for this is probably the tradition that patients must have a haemoglobin of 10 g dl1.
Inappropriate use of blood squanders a limited resource, causes unwanted side effects, and raises the cost of patient care. Inappropriate transfusions can be prevented by using strict preset criteria for triggering homologous blood administration. In selected patients, allogenic transfusion can be reduced by autologous blood transfusion, intraoperative blood salvage, or intraoperative isovolaemic haemodilution.
Donated blood is a limited resource although appropriate blood transfusion can be life saving. It is essential that better blood transfusion practices are incorporated into clinical protocols and that blood transfusion is made safer while avoiding its unnecessary use in clinical practice.11 We consider that intraoperative haemoglobin estimation is an effective and simple objective measurement to increase the incidence of appropriate transfusions.
The shortcoming of our study was that the audit team recorded the data after the transfusion event had taken place. It is noteworthy that none of the cases studied here had the indication for transfusion recorded in the case notes. The value of a prospective audit can be seen in the gradual but dramatic reduction in blood use and an improvement in the appropriate use of blood over a period of 3 months.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Hallissey MT, Fielding JWL, Crowson MC, et al. Blood transfusion: an overused resource in colorectal cancer surgery. Ann R Coll Surg Eng 1992; 74: 5962[ISI][Medline]
3 Habibi S, Coursin DB. Trauma and massive haemorrhage. In Muravechick S, Miller RD, eds, Atlas of Anaesthesia Subspecialty Care. San Francisco: Churchill Livingstone, 6.26.17
4 Lawrence TG, Mark EB, Michael HK, James PA. Transfusion medicine first of two parts. Blood Transfusion. N Eng J Med 1990; 340: 43847[CrossRef]
5 ASA Task Force. Practice guidelines for blood component therapy. Anaesthesiology 1996; 84: 32
6 Giovanetti AM, Parravicini A, Baroni L, et al. Quality assessment of transfusion practice in elective surgery. Transfusion 1988; 28: 1669[CrossRef][ISI][Medline]
7 Rao MP, Boralessa H, Morgan C, et al. Blood component use in critically ill patients. Anaesthesia 2002; 57: 5304[CrossRef][ISI][Medline]
8 Messmer KFW. Acceptable haematocrit levels in surgical patients. World J Surg 1987; 11: 416[Medline]
9 Red Blood Cell TransfusionConsensus Conference. JAMA 1988; 260: 27002703[CrossRef][ISI][Medline]
10 Mozes B, Epstein M, Ben-Bassat I, et al. Evaluation of the appropriateness of blood and blood product transfusion using preset criteria. Transfusion 1989; 29: 298303[CrossRef][ISI][Medline]
11 Department of Health Circular. HSC, July 2002/009, Better Blood Transfusion 2