Medicine of the 21st century can boast of its rapid progress and valuable experience in various fields. The urge for finding better treatment solutions has resulted in new surgical techniques and sophisticated equipment. The expansion of minimally invasive surgery and different coagulation devices have contributed to minor surgical blood losses. Nevertheless, surgery remains the field of medicine with the highest amount of blood cross-matching [1]. Blood derivatives are frequently ordered without proper analysis of the real needs. In many hospitals, the standards concerning surgical blood supply have not been changed for years.

The first relevant data regarding preoperative blood over ordering were presented by Friedman and colleagues in 1973 [2]. Based on them, the maximum surgical blood order schedule (MSBOS), promoting efficient blood utilization, was prepared. In the study in question, the national cross-match-to-transfusion ratio (C:T) was used to evaluate unnecessary preoperative cross-matching.

A number of studies carried out later in different countries have confirmed that blood ordering-related problems are more common than expected [3, 4, 5, 6]. In 2003, Palmer and co-workers  [1] proposed another scheme, the patient specific blood ordering system (PSBOS), to assess potential operative transfusion needs. The authors suggested the lowest tolerated haematocrit of 21%, except for patients with ischemic heart disease or  those with ASA ≥ III. 

The available studies show that approximately 60% of all blood transfusions are performed in the operating room [1, 7]. Over ordering of surgical blood may be the source of the unnecessary blood storage in blood banks, when other patients may require immediate blood transfusions.

The aim of this study was to determine whether preoperative blood cross-matching in our hospital is well adjusted to the actual intraoperative blood requirements and whether the standards should be revalidated. The main purpose of the study  is to emphasize the problem of blood over ordering and the need of reasonable utilization of blood derivatives.

METHODS

The retrospective study was performed at the Department of Anaesthesiology and Intensive Therapy,  Medical University of Gdańsk in July 2007. The records of all patients scheduled for surgery during this period were analysed.  

The intraoperative requirement, ordering and transfusion practices were evaluated. The number of RBC units cross-matched before surgery and those actually transfused in the operating room were calculated.   

Patients treated in seven departments were enrolled: general, vascular, thoracic, oncologic, trauma, plastic and maxillofacial surgery. It has to be emphasized that some surgical procedures that usually do not demand blood transfusions involve the risk of large vessel injury and hence blood preservation for them is obligatory and incontrovertible.

The main outcome measures used in the analysis were: (1) the cross-match to transfusion ratio - C/T ratio, (2) the number of patients transfused x 100 to the number of patients cross-matched (transfusion probability – %T) and (3) the number of units transfused relative to the number of patients cross-matched (transfusion index – TI). Calculations of  MSBOS were abandoned due to large diversity of surgical procedures carried out. MSBOS = 1.5 x TI according to the Mead’s criterion and is calculated separately for elective procedures [2, 8, 9].

RESULTS

The values justifying blood ordering were: C/T ratio ≤3.0, %T ≥30 and TI ≥0.5.

The number of RBC units cross-matched depends on the type of procedure and estimated blood loss. Therefore, the studied cases were divided into four groups: (1) high, (2) medium, (3) low and (4) minimal potential risk of blood loss.

The blood was cross-matched for 165 of 329 patients included.

The remaining 164 patients underwent the procedures, in which the anticipated blood loss is insignificant and they usually do not require blood transfusion, e.g. appendectomy, inguinal hernia repair, laparoscopic cholecystectomy, mastectomy, skin melanoma excision. These procedures were qualified as the fourth group, which also included most of the plastic (29 out of 32) and maxillofacial (17 out of 18) surgical procedures. In the statistical analysis,  only patients with blood cross-matching were considered. 

The total number of cross-matches was 405 for 165 and of transfusion - 45 for 18 patients( C/T ratio = 9, %T = 10.9 and TI = 0.27).

The first group of procedures included all laparotomies and thoracotomies performed due to oncological, traumatic or other indications, as well as severe bone fractures, major vascular surgery and proximal limb amputations. There were 85 operations of high risk of blood loss (51.5% of all surgeries), 238 blood units were cross-matched for them (58.7% of all cross-matches) and 36 were transfused to 16 patients (80% of all transfusions). The C/T ratio was found to be 6.61, %T = 18.8 and TI = 0.42.

The second group contained 46 cases (27.8%); 96 blood units were cross-matched (23.7% of cross-matches) and 7 were transfused to 4 patients (15.5% of transfusions). The types of procedures were laparoscopic and videoscopic surgery, thyroidectomy, distal limb amputations, bone fractures and peripheral vascular surgery. The calculated C/T ratio was 13.7, %T = 8.69 and TI = 0.15.

Thirty-four patients underwent procedures of low blood loss risk, e.g. diagnostic laparoscopies, thoracoscopies, mediastinoscopies, umbilical hernioplasty, videosympathectomies, videosplanchnicectomies and bedsore treatment (20.7% of all procedures); 71 RBC units were cross-matched (17.6% of all) and 2 (4.5%) were transfused to one patient. The calculated C/T ratio was 35.5, %T - 2.94 and TI - 0.058.

DISCUSSION

Blood is a valuable tissue. Each blood unit has to be tested before being transfused to provide its safety, which generates enormous costs. Since blood derivatives are expensive and valuable, thoughtful exploitation is relevant mostly for the sake of patients and for hospital economy.

Despite the widespread blood donation campaign, the blood needs still exceed its supply. Shelf life of a RBC unit is only 42 days [10]. Most of ordered blood is not used but kept in reserve in blood banks for 48 hours, which makes it unavailable for others in need.  Morphologic and biochemical changes that occur during RBC storage may hinder the erythrocyte viability and function following transfusion [10, 11]. The evidence for a significant detrimental clinical effect related to transfusion of older blood is inconclusive, yet it demands attention. Though there is no published data establishing normative thresholds of RBC unit wastage, the amount of outdated blood is frequently unsatisfactory [3, 12].

Individual surgical procedures involve different risks of blood loss. In this respect, MSBOS was the solution. MSBOS is a table of elective surgical procedures which lists the number of units of blood routinely cross-matched for them pre-operatively, based on retrospective analysis of actual blood usage [9]. In our analysis, however, the studied group was too heterogeneous and the number of elective surgical procedures too small to calculate MSBOS.

Standards were estimated using the C/T ratio. Procedures with the C/T ratio above 3 (which corresponds to a blood usage less than 30%)  should be in the category catered for group and antibody screen only [9]. In our study the results were similar; in the fourth group blood cross-matches were not present. Some individual features, such as the distance from the operating room to the blood bank, the presence of antibodies in patients blood or low preoperative haematocrit, should always be considered [1, 9].

Yet MSBOS also has its opponents. Palmer and co-workers [1] in their study published in 2003 attempted to demonstrate that the PSBOS was more accurate in predicting the number of blood transfusions compared to MSBOS. PSBOS includes patient and surgeon variables in transfusion prediction; in the study mentioned, the system helped to reduce the number of patients who had blood cross-matched pre-operatively. In our study we could not use PSBOS because of a large number of surgeons performing surgeries.

Irrespective of the schedule used, the standards should be individualized for each hospital. A variety of studies on the MSBOS can be found in literature, their findings differ slightly [4, 13, 14, 15]. Nevertheless, the same main outcome measures to estimate blood cross-matching requirements were used in each study. The cross-match to transfusion ratio was first suggested by Boral and Henry in 1975 [4] and was found to be most correlated with the actual blood usage. According to different authors, the desirable C/T ratio varies from 2 [2], through 2.5 [1] to 3 [8]. In our hospital, the C/T ratio is higher even in the first group with the highest risk of bleeding – 6.61; in the second group this ration is 13.7 and in the third group -  35.5. This suggests that routine preoperative RBC cross-matching is not necessary yet each surgical procedure should be considered individually. The transfusion probability (%T) was introduced by Mead and colleagues in 1840 [8] and the value of 30 has been suggested as significant. In our study, %T varied: 18.8 in the first group, 8.69 in the second and 2.94 in the third group, which demonstrates that our policy of perioperative blood ordering should be changed.

The transfusion index (TI) is an average number of units used per patient cross-matched and  determines whether the number of units ordered is appropriate. According to Boeral and Henry [4], TI = 0.5 means significant blood utilization [4]. Our findings are as follows: 0.42 in the first group, 0.15 in the second and 0.058 in the third group, which indicates that only in the first group the blood ordering scheme is acceptable. 

The results of our study show how indolent the intra-operative transfusion practices in our hospital are. Our future goal is to design an explicit maximum order policy based on evidence-based medicine in order to utilize blood derivatives more reasonably and economically.

CONCLUSION

The preoperative blood cross-matching is far from being adjusted to actual blood requirements and the standards should be revalidated.

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REFERENCES

1.     Palmer T, Wahr JA, O’Reilly M, Greenfield ML: Reducing unnecessary cross-matching: a patient-specific blood ordering system is more accurate in predicting who will receive a blood transfusion than the maximum blood ordering system. Anesth Analg 2003; 96: 369-375.

2.     Friedman BA, Oberman HA, Chadwick AR.: The maximum surgical blood order schedule and surgical blood use in the United States. Transfusion 1976; 16: 380-387.

3.     Novis DA, Renner S, Friedberg R.: Quality indicators of blood utilization. Arch Pathol Lab Med 2002; 126: 150-156.

4.     Vibhute M, Kamath SK, Shetty A: Blood utilization in elective general surgery cases: requirements, ordering and transfusion practices. J Postgard Med 2000; 46: 13-17.

5.     David S. de Jong H: Improved utilization of blood for elective surgery. Surgery, Gynecology and Obstetrics 1983; 156: 326-328.

6.     Horsey PS: Blood transfusion and surgery. Br Med J (Clin Res Ed.) 1985; 291(6490)-294.

7.     Friedman BA: An analysis of surgical blood use in United States hospitals with application to the maximum surgical blood order schedule. Transfusion 1979; 19: 268-278.

8.     Mead JH, Anthony CD, Sattler M: Hemotherapy in elective surgery: an incidence report, review of literature and alternatives for guideline appraisal. Am J Clin Path 1980; 74: 223-227.

9.     Cann R, Chapmann J, Dodsworth H, Napier JAF, Waters AH: Guidelines for implementation of a maximum surgical blood order schedule. Clin Lab Haemat 1990; 12: 321-327.

10.    Vandromme MJ, McGwin G Jr, Weinberg JA: Blood transfusion in the critically ill: does storage age matter? Scand J Trauma Resusc Emerg Med 2009; 17: 35.

11.    Hess JR: Red cell storage. J Proteomics 2009; 73: 1-180.

12.    Clark JA, Ayoub MM: Blood and component wastage report. Transfusion 1989; 19: 139-142.

13.    Chawla T, Kakepoto GN, Khan MA: An audit of blood cross-match ordering practices at the Aga Khan University Hospital: first step towards a maximum surgical blood ordering schedule. J Postgrad Med 2000; 46: 13-7.

14.    Jayaranee S, Prathiba R, Vasanthi N, Lopez CG: An analysis of blood utilization for elective surgery in a tertiary medical centre in Malaysia. Malays J Pathol 2002; 24: 59-66.

15.    Foley CL, Mould T, Kennedy JE, Barton DP: A study of blood cross-matching requirements for surgery in gynecological oncology: improved efficiency and cost saving. Int J Gynecol Cancer 2003; 13: 889-893.

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address:

*Marta Kozarzewska
Studenckie Towarzystwo Naukowe
Gdański Uniwersytet Medyczny
ul. Dębinki 7, 80-211 Gdańsk
tel.: 58 349 24 06

received: 27.02.2011
accepted: 16.05.2011