Homologous blood transfusion is not required in surgery for adolescent idiopathic scoliosis

Transcription

1 Homologous blood transfusion is not required in surgery for adolescent idiopathic scoliosis R. R. Verma, J. B. Williamson, H. Dashti, D. Patel, N. J. Oxborrow From the Royal Manchester Children s Hospital, Manchester, England We studied 70 consecutive patients with adolescent idiopathic scoliosis who underwent corrective surgery. They were divided into two groups. In the study group of 38 patients one or more modern blood-conservation measures was used peri-operatively. The 32 patients in the control group did not have these measures. Both groups were similar in regard to age, body-weight, the number of levels fused and the type of surgery. Only two patients in the study group were transfused with homologous blood and these transfusions were off-protocol. Wastage of autologous pre-donated units was minimal (6 of 83 units). By contrast, all patients in the control group were transfused with homologous blood. In the study group there was a significant decrease (p = 0.005) in the estimated blood loss when all the blood-conservation methods were used. The use of blood-conservation measures, the lowering of the haemoglobin trigger for transfusion and the education of the entire team involved in the care of the patient can prevent the need for homologous blood transfusion in patients undergoing surgery for adolescent idiopathic scoliosis. R. R. Verma, Specialist Registrar in Orthopaedics J. B. Williamson, Consultant in Spinal Surgery, Honorary Senior Lecturer in Orthopaedic Surgery H. Dashti, Consultant in Spinal Surgery D. Patel, Consultant Anaesthetist N. J. Oxborrow, Consultant in Spinal Surgery Royal Manchester Children s Hospital, Pendlebury, Manchester M27 4HA, UK. Correspondence should be sent to Mr J. B. Williamson; brad.williamson@ cmmc.nhs.uk 2006 British Editorial Society of Bone and Joint Surgery doi: / x.88b $2.00 J Bone Joint Surg [Br] 2006;88-B: Received 31 January 2006; Accepted after revision 16 May 2006 There is an increasing awareness of the need to avoid homologous blood transfusion in elective surgery. This stems from a better appreciation of its adverse effect and from the increasing pressure on blood stocks 1 due to restrictions on potential donors. 2 With this in mind we have established a policy of trying to avoid homologous blood transfusion in our paediatric spinal surgery practice. This policy has a number of aspects: 1) the establishment of an integrated care pathway for children undergoing spinal surgery in which the need to avoid homologous transfusion is emphasised; 2) the use of an autologous pre-donation programme, in which the children are encouraged to participate; 3) the use of blood-conserving anaesthetic techniques such as controlled hypotension, acute normovolaemic haemodilution and infusion of aprotonin; 4) the establishment of a transfusion trigger; and 5) the use of intra-operative cell salvage. Our study examines the effect of this change in practice on patients having surgery for adolescent idiopathic scoliosis. We chose this group because the patients were of similar age and were undergoing surgery of similar severity. We also felt that our blood-conserving strategies were appropriate to their needs. Patients and Methods We carried out a retrospective review of the complete records of the first 46 patients who underwent surgical correction of an adolescent idiopathic scoliosis after the introduction of our blood-conserving strategy. These were compared with those of the 32 patients with adolescent idiopathic scoliosis operated on immediately before this policy commenced. In the study group there were 33 girls and five boys (eight patients had been excluded because they had anterior surgery alone for their scoliosis) and in the control group 30 girls and two boys. In the study group 24 patients had undergone sequential combined anterior and posterior surgery and 14 posterior surgery alone. The control group had 18 sequential combined procedures and 14 posterior procedures. Patients in the study group were managed according to our integrated care pathway and assigned a transfusion trigger haemoglobin level of less than 7 g/dl. 3-5 They also took part in one or more of the following blood-conservation strategies. Pre-operative autologous blood donation. All children having surgery for adolescent idiopathic scoliosis were encouraged to join the pre-operative autologous blood donation programme. The educational component took the VOL. 88-B, No. 9, SEPTEMBER

2 1188 R. R. VERMA, J. B. WILLIAMSON, H. DASHTI, D. PATEL, N. J. OXBORROW form of detailed discussion with the surgeon and nurse specialist, supplemented by information leaflets and followed by informed consent for each donation. The patients physical fitness was assessed to ensure that they had no significant respiratory, cardiac or cerebrovascular disease, and did not take any medication which would preclude autologous blood collection. Specific exclusion criteria were anaemia, poor venous access, active infection, cardiovascular disorders such as critical stenotic valvular disease, cyanotic heart disease, arrhythmia, severe restrictive or obstructive airways disease, cerebrovascular disorders such as epilepsy, cerebral tumour or transient ischaemic attacks and infective viral diseases such as hepatitis B or C or HIV or human T-lymphocyte virus (HTLV) infection. The haemoglobin level was measured each week before donation. If the pre-donation haemoglobin was less than 11 g/dl the collection was deferred until the anaemia had been rectified. Patients were maintained on oral ferrous sulphate therapy (200 mg three times daily if over 45 kg bodyweight and twice daily if under 45 kg), from one week before the first donation until the day of surgery. Since only one size of blood-collection bag was available to us, and this was pre-dosed with anticoagulant, a collection of at least 405 ml was required. In effect, this precluded children of less than 30 kg of body-weight from donation. To prevent dizziness, nausea and fainting due to hypovolaemia, an infusion of an equal volume of normal saline was given to the children in the other arm. The donation process was managed by the nurse-led hospital venous access team. After donation, the blood was transferred to the hospital blood bank where it was stored in a separate, designated refrigerator until the date of operation when it was crossmatched and subjected to the same handling and checks as donated homologous blood. Acute normovolaemic haemodilution. Children who did not take part in the pre-operative autologous blood donation programme, possibly because of a needle-phobia, and those who came to surgery with a haemoglobin level of more than 11 g/dl underwent acute normovolaemic dilution. This was carried out in the anaesthetic room after induction of anaesthesia and insertion of invasive monitoring. The approximate volume of blood to be collected was calculated and rounded down to a multiple of the blood-bag volume according to the following equation: Volume to be collected = estimated blood volume (weight x 70 ml kg -1 ) (Hbs - Hbt)/Hbav, where Hbs was the starting haemoglobin level, Hbt was the target haemoglobin (the haemoglobin achieved after acute normovolaemic haemodilution) and Hbav was the mean haemoglobin (i.e. the mean of the starting and target Hb). This equated to two 450 ml bags. The volume removed was determined by accurately weighing the collection bag. An equal volume of Gelofusine (B Braun Medical Inc, Sheffield, United Kingdom) was infused intravenously into the other forearm to replace the blood collected. Each unit of blood was immediately labelled with the patient s name, hospital number and time of withdrawal and was placed in a blood-storage box. The blood was kept in the same operating room as the patient and maintained at room temperature to preserve maximum platelet function. It was refrigerated only if it was anticipated that more than eight hours would elapse before re-infusion. 6 In the event of such a delay, it was returned to the hospital blood bank where it was cross-matched and checked before being re-issued. Refrigerated units which were not used within 24 hours were discarded. The blood was re-infused after major blood loss had ceased or sooner if indicated. The estimated blood loss, serial haematocrit determinations and cardiovascular parameters were used to guide intra-operative transfusion. The estimated blood loss (EBL) was calculated as follows: EBL = volume of blood processed by the cell saver + volume of blood on surgical swabs - volume of citrate-phosphate-dextrose-adrenaline solution used in the cell saver and for washing the swabs. Controlled peri-operative hypotension. The mean arterial blood pressure was kept between 50 mmhg and 60 mmhg during surgery to minimise intra-operative blood loss. This was achieved by using 0.6 to 0.7 minimal alveolar concentration of sevoflurane inhalation anaesthetic and an infusion of 0.1 to 0.5 µg kg -1 min -1 of remifentanil, a potent ultra-short-acting opioid. Other vasoactive drugs were not needed to achieve the desired blood pressure. The cardiac output was continuously assessed using the Deltex CardioQ oesophageal doppler (Deltex Medical Group plc, Chichester, United Kingdom). Central venous cannulation was not used routinely unless the patient was having sequential anterior and posterior surgery. Aprotonin. This is a serine protease inhibitor of plasmin, trypsin and plasma and tissue kallikrein (serine proteases involved in the clotting cascade that liberate kinin from kininogen). It preserves platelet function and has been shown to reduce blood loss significantly in cardiac, liver and orthopaedic surgery. Recently, it has been shown to reduce blood loss in surgery for scoliosis in adults and children. 7 An intravenous test dose of aprotonin of 3 ml was followed by a loading dose of 4 mg kg -1 over 30 minutes. It was then continuously infused at a rate of 1 mg kg -1 hr -1 throughout the duration of the surgery. Use of intra-operative cell salvage. A Haemonetics cell saver 5 (Haemonetics Corporation, Braintree, Massachusetts) was used from 2000 to 2004 and a Fresenius CATS (Fresenius Haemotechnology Inc, Redmond, Washington) in Our standard practice was to have two suction catheters at the operating table, one to suck away the smoke plume associated with the use of cutting diathermy, and the other to clear blood from the operative field. We also routinely washed all blood-soaked swabs in citrate-phosphate- THE JOURNAL OF BONE AND JOINT SURGERY

3 HOMOLOGOUS BLOOD TRANSFUSION IS NOT REQUIRED IN SURGERY FOR ADOLESCENT IDIOPATHIC SCOLIOSIS 1189 Table I. Overall mean results (range) for the study and control groups Study group (n = 38) Control group (n = 32) p value Pre-donation Hb * (g/dl) 13.8 (11.5 to 16.5) (11.8 to 15.8) 0.40 Levels fused 12.2 (7 to 14) 12.1 (9 to 14) 0.73 Hb on discharge (g/dl) 10.2 (8.5 to 13.4) 11.2 (9 to 14.3) Estimated blood loss (ml) 1296 (450 to 2100) 1783 (500 to 4200) Table II. Mean results (range) for sequential anterior and posterior surgery Study group (n = 24) Control group (n = 18) p value Pre-donation Hb * (g/dl) 13.4 (11.5 to 15) 13.4 (11.8 to 14.4) Levels fused 12.5 (9 to 14) 12.3 (9 to 14) 0.61 Hb on discharge (g/dl) 10.4 (9 to 12.7) 11.1 (9.7 to 12.8) Estimated blood loss (ml) 1364 (500 to 2100) 1669 (600 to 3500) Table III. Mean results (range) for posterior surgery Study group (n = 14) Control group (n = 14) p value Pre-donation Hb * (g/dl) 14.2 (12.7 to 16.5) 13.8 (11.9 to 15.8) Levels fused 11.6 (9 to 13) 11.7 (7 to 14) Hb on discharge (g/dl) 9.9 (8.5 to 13.4) 11.3 (9 to 14.3) Estimated blood loss (ml) 1178 (600 to 2100) 1929 (500 to 4200) dextrose-adenine solution (CPDA-1). 8 The resulting solution was processed through the cell saver. Statistical analysis. This was undertaken using the SPSS statistical program (version 11; SPSS Inc., Chicago, Illinois). Student s t-test was used for parametric analysis and the Mann-Whitney U test for non-parametric analysis. A p value of < 0.05 was considered to be significant. Results Role of blood-conservation measures. By using all the bloodconservation measures described, we were successful in avoiding homologous blood transfusion in most patients (36 of 38). An overall comparison of the pre-donation haemoglobin level, the levels fused, the discharge haemoglobin and the estimated blood loss in the two groups is presented in Table I. The same data for patients having sequential anterior and posterior surgery, and posterior surgery alone are given in Tables II and III. There was no statistical difference in the type of surgery undertaken between the study and control groups (p = 0.628). There was a significant overall reduction in the mean estimated blood loss in the study group (p = 0.005). In patients having posterior surgery alone or sequential surgery, the estimated blood loss was less in the study than in the control group. Although there was a statistically significant difference in the level of haemoglobin on discharge and post-operative haemoglobin between the two groups, this was not clinically significant and both groups were asymptomatic. In retrospect, the control group was perhaps over-transfused in the peri-operative period. Only two patients in the study group were transfused with homologous blood. Junior members of the criticalcare staff initiated both transfusions without consultation with the surgical or anaesthetic teams, and both transfusions fell outside the agreed protocols. Had the protocols been observed, the study group would not have been exposed to any homologous blood products. Almost all of the pre-donated autologous blood was re-infused. Only six of 83 units (7.2%) of pre-donated blood were discarded because they were not required. By contrast in the control group, 167 units were crossmatched and 126 blood units were used, giving a crossmatch/transfusion ratio of A mean of 3.94 units (2 to 10) was transfused per patient. In addition, a total of 36 pints of fresh-frozen plasma was used. Discussion Our study shows that by using a simple blood-management strategy it is possible to perform complex spinal surgery without the need for homologous blood transfusion. Corrective surgery for scoliosis in children and adolescents may be associated with major blood loss. 9 Advances in surgical technique and instrumentation allow operative intervention for increasingly complex spinal deformities, thereby increasing the potential for blood loss. Several simple techniques are used routinely during spinal fusion surgery to avoid homologous transfusion, such as the positioning of the patient to avoid abdominal compression, VOL. 88-B, No. 9, SEPTEMBER 2006

4 1190 R. R. VERMA, J. B. WILLIAMSON, H. DASHTI, D. PATEL, N. J. OXBORROW controlled hypotensive anaesthesia, acute normovolaemic haemodilution, the application of fibrin sealant to decorticated bone and the peri-operative infusion of shed blood Recently, the systemic administration of antifibrinolytic drugs such as aprotonin 7,15-17 and Amicar (Amicar Wyeth- Ayerst, Collegeville, Pennsylvania) 15,18,19 have been shown to reduce blood loss during complex reconstructive spinal surgery. Despite these advances, homologous blood transfusion is still frequently required. 20 Although other studies in spinal surgery have examined the effect of a single alteration in practice on transfusion requirements, few have eliminated the need for homologous transfusion. To our knowledge, our study is the first to evaluate the effects of a comprehensive blood-management strategy on transfusion requirements, and the first to show that with such a strategy homologous transfusion can be avoided. A number of studies in the USA and Europe appear to show that pre-operative autologous blood donation is effective in eliminating the need for homologous blood transfusions However, these were in specialties in which the expected blood loss was less than that in complex spinal surgery. Pre-operative autologous blood donation alone would probably not have been sufficient to eliminate the need for transfusion in this particular group of patients. Although the donated homologous blood is generally safe, its avoidance will minimise any inherent risks. Firstly, there is a risk of immunological modifications. 26 A transfusion-related immunomodulation effect has been implicated in the increased post-operative rate of infection observed in patients who receive homologous blood The infection rate in patients undergoing posterior spinal instrumentation is relatively high, 30,31 and therefore the effects of reducing the immune response are not to be underestimated. Secondly, the possibility of transmission of disease remains. The likelihood of contracting a blood-borne infection such as HIV or hepatitis from donated blood in the United Kingdom is very small, but not negligible. The risks are estimated at about 1 in for hepatitis B, less than 1 in 30 million for hepatitis C and less than 1 in several million for HIV infection. 32 The risk of transmission of v-cjd is not yet known. 32 These are clearly obviated if autologous blood is used, but the risk of transfusion-transmitted bacterial infection by contamination still remains 33 since the technique of blood collection and storage does not differ from that for homologous blood. Our patients were mainly young girls who had their child-bearing years ahead of them. Exposure to homologous blood antigens gives them the opportunity to form antibodies, thereby increasing the risk of haemolytic disease of the newborn. 34 In previous studies on elderly autologous blood donors, allo-immunisation, which occurs in approximately 1% to 2% of patients transfused with homologous blood, was not considered to be a risk factor. 35 However, in our study population of girls approaching child-bearing age, this could pose a significant health risk during a future pregnancy. Although not all antibodies which result from homologous blood transfusion cause haemolytic disease of the newborn, sensitised patients would require, at minimum, increased pre-natal screening and could require amniocentesis and fetal transfusion. In the Serious Hazards of Transfusion report of 2003, incidents were described of incorrect or inappropriate transfusion of blood components, an increase of 25% over the previous 12 months. They received no reports that year of adverse reactions relating to autologous pre-deposit donation. This is perhaps to be expected since the number of patients undergoing pre-operative autologous blood donation remains small, relative to the total number undergoing homologous transfusion. It is expected that pre-operative autologous blood donation transfusions would be given by staff with an interest in good transfusion practice, who would have a more careful approach. The efficacy of various methods of blood conservation have been reviewed in other studies. We have shown that a combination of these methods has significantly reduced exposure to homologous blood products in surgery for scoliosis and that it is possible to perform complex spinal surgery without recourse to homologous blood. The two patients in our study group who received a transfusion of homologous blood were transfused outside our protocol by members of the critical-care staff. It is not our usual practice for such patients to be nursed on the intensive-care unit, but a small number were admitted there because of the lack of a high-dependency bed. The immediate medical care in the intensive-care unit is provided by dedicated criticalcare staff who only occasionally manage surgical and especially spinal patients. They were therefore unaware of our dedicated blood-management policy, hence the inappropriate transfusions. The importance of engaging all staff in a change such as this is demonstrated. In 2003 the EU issued a directive to set standards for quality and safety for the collection, testing, processing, storage and distribution of human blood and blood components. 37 The Medicines and Healthcare Products Regulatory Agency in the United Kingdom has confirmed that pre-operative autologous blood donation can only be undertaken by a licensed blood establishment, and hospitals wishing to process blood products have to apply to the agency for accreditation. Although this may have a negative impact in some centres, pre-operative autologous blood donation continues in our unit, after accreditation, without any problems. We have shown that when comprehensive blood-conservation strategies are used, it is possible to perform complex spinal surgery in healthy children without the need for homologous blood transfusion. Whilst some of these techniques may be considered for an adult population it should be emphasised that adult patients may have concurrent medical conditions which could preclude the use of similar methods of blood conservation. THE JOURNAL OF BONE AND JOINT SURGERY

5 HOMOLOGOUS BLOOD TRANSFUSION IS NOT REQUIRED IN SURGERY FOR ADOLESCENT IDIOPATHIC SCOLIOSIS 1191 No benefits in any form been received or will be received from a commercial party related directly or indirectly to the subject of this article. References 1. Vanderlinde ES, Heal JM, Blumberg N. Autologous transfusion. BMJ 2002;324: National Blood Service. (accessed 22/11/2005). 3. No authors listed. Practice guidelines for blood component therapy: a report by the American Society of Anesthesiologists Task Force on blood component therapy. Anesthesiology 1996;84: Hebert PC, Wells G, Blajchman MA, et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care: transfusion requirements in critical care investigators, Canadian Critical Care Trials Group. N Engl J Med 1999; 340: Hill SR, Carless PA, Henry DA, et al. Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion. 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