Materials and methods

Donors and marrow harvests

In the present study, 574 consecutive BM harvests from 400 sibling and 168 unrelated donors between July 1981 and October 2001 at the Helsinki University Central Hospital were retrospectively evaluated. All unrelated donors were from the Finnish Bone Marrow Donor Registry. In all, 24 BM harvests from sibling donors were excluded from the analysis for the following reasons: 10 donors had been transfused with allogeneic blood before the Hb determination on the morning following the harvest, seven donors were underage, five lacked sufficient information, one donor redonated to the same patient with a short time interval (26 days) between the harvests, and one donor had von Willebrand's disease. In all, 55 marrow harvests from unrelated donors were not included in the study because the recipient was a child and a decision had been made prior to the medical evaluation not to collect an autologous blood unit from the donor. The characteristics of the 495 harvests are presented in Table 1. Two sibling donors donated twice to the same patient. One unrelated donor donated three times to two different patients, and one unrelated donor donated twice to the same patient. The time interval between the marrow harvests from the same donor ranged from 16 weeks to 62 months. Marrow was harvested with small aspirations of approximately 3 ml, and the median total harvested volume was 900 ml. The median number of nucleated cells was 3.2 10⁸/kg patient weight. In eight harvests from sibling donors and in one harvest from an unrelated donor, the nucleated cell dose was below 2 10⁸/kg patient weight. Marrow collection was performed from the posterior iliac crests, and, when necessary, also from the sternum (126 donors). During the years 1981–1983, the BM collections were performed either under epidural anaesthesia or general anaesthesia, thereafter only under general anaesthesia, except one under spinal anaesthesia from a donor with symptoms of respiratory infection.

Table 1 - Characteristics of the BM harvests.

Full table

The median and mean Hb concentrations were calculated separately for donors autotransfused, for donors from whom an autologous blood unit was collected but not reinfused, and for donors from whom an autologous blood unit was not collected (Table 2). The donors from whom an autologous blood unit had been drawn but not reinfused (N=27) and those who had no autologous unit collected (N=77) were included in the group 'not autotransfused'. The Hb concentrations in these two subgroups were very similar at all measurements.

Table 2 - Hb concentrations (g/l) prior to and after the BM harvest in adult donors to adult recipients.

Full table

Hb determinations

The Hb concentrations were measured in blood samples drawn from the donors at the time of the medical evaluation before the donation of an autologous blood unit, usually 2–5 weeks prior to the BM harvest, at the time of entering the hospital on the day before the harvest, and on the morning following the harvest. None of the donors was transfused with allogeneic blood between the Hb determinations.

Collection of autologous blood

One unit of blood (450 ml) was routinely collected from the donors at the time of the medical evaluation 2–5 weeks before the harvest. The blood was taken into CPDA-1 whole-blood bags, which can be stored for 35 days. The bags were kept at a temperature of 2–6°C in a blood refrigerator at the hospital blood centre. The autologous blood unit was transfused to the donor after the harvest, usually without Hb checking, on the same day.

Statistics

T-test for two independent samples was used to compare the mean Hb concentrations between the groups of autotransfused and not autotransfused donors.

Results

An autologous blood unit was stored from 418 of the 495 donors (84%; Table 2). Of the 418 donors, 27 (6.5%) with autologous blood stored were not autotransfused. The autologous blood unit was outdated at the time of the marrow harvest because of the postponement of the transplantation in 13 cases, and the transfusion was regarded as unnecessary in 11 cases either because of a relatively high Hb level (>125 g/l) in an extra determination immediately after the harvest or because of the small volume of marrow harvested (<600 ml). Three donors did not receive an autotransfusion for an unknown reason.

A blood unit was never stored from 77 donors (Table 3). The most common reason was that, due to the nature of the disease of the patient, proceeding to the transplantation was not certain or the date of transplantation was unknown. The time interval from the donor's medical evaluation to transplantation was short (<14 days) in 21 cases and long (>35 days) in two cases. In nine cases, the suitability of the donor for general anaesthesia and BM harvest was uncertain at the time of the medical evaluation or the donor felt sick after blood samples had been drawn. In six cases, the donor participated in the EBMT study comparing transplantation with BM or peripheral blood progenitor cells (PBPCs),² and the type of donation was not yet known at the time of the medical evaluation.

Table 3 - Reasons for not collecting autologous blood at the time of donor medical evaluation.

Full table

At the time of the medical evaluation, the mean Hb concentrations were similar, 136 and 137 g/l, in the female donors autotransfused or not autotransfused later at the time of the BM harvest (Table 2). In the male donors later autotransfused, the Hb concentration was 151 g/l and in those not autotransfused 153 g/l (P=0.041). Just before the BM harvest, the Hb concentrations were significantly higher in the donors who were not later autotransfused than in those autotransfused after the marrow harvest (135 vs 128 g/l in the female donors, P<0.001, and 151 vs 143 g/l in the male donors, P< 0.001). On the morning after the harvest, the Hb concentration was 104 g/l in the female donors autotransfused and 100 g/l in those not autotransfused (P=0.083). In the male donors autotransfused, the post-harvest Hb level was significantly higher, 122 g/l, than in those not autotransfused, 117 g/l (P<0.001). It was not possible to calculate the volumes of crystalloids given to the donors precisely because the volume of fluid infused from the last crystalloid solution bag was not recorded in every case. The mean registered volumes of crystalloids infused to the donors not autotransfused were significantly higher than those infused to the autotransfused donors (2880 vs 2670 ml, P=0.01).

In all, 14 of the 391 donors who were autotransfused (3.6%) and 11 of the 104 donors not autotransfused (10.6%) had an Hb level <90 g/l on the morning following the harvest (Table 4). Of the 14 autotransfused donors with the Hb level <90 g/l, 13 were females. The weight of 10 female donors was <60 kg (median 54 kg; range 50–81 kg). The range of the pre-harvest Hb level in these 13 female donors was 112–130 g/l. The only male donor with a post-donation Hb <90 g/l weighed 49 kg. Of the 11 donors not autotransfused with an Hb concentration <90 g/l after the harvest, 10 were females. Only three donors in this group weighed <60 kg, the median weight being 62 kg (range 55–83 kg). The pre-harvest Hb level ranged from 117 to 136 g/l. Two of the donors had donated an autologous blood unit and nine had not.

Table 4 - Number (%) of donors with a low Hb concentration (g/l) after the harvest.

Full table

Four female donors had an Hb concentration <85 g/l on the morning following the harvest (Table 4). Two of them had been autotransfused. The pre-harvest Hb concentrations in these autotransfused donors were 118 and 126 g/l and the post-harvest Hb concentrations 83 and 79 g/l, respectively. The weights of these donors were 59 and 54 kg and the BM volumes harvested 1000 and 1200 ml. An autologous blood unit had not been collected from two other donors with a post-donation Hb <85 g/l. Their pre-harvest Hb levels were 117 and 128 g/l and the postharvest Hb concentrations 75 and 83 g/l. The donors weighed 83 and 61 kg, and the volumes of marrow harvested were 900 and 1000 ml, respectively.

Discussion

In the present study, the hospital charts of 568 consecutive sibling and unrelated donors were reviewed in order to determine how necessary it is to collect autologous blood before BM harvest to be reinfused at the time of the donation. The guidelines of the World Marrow Donor Association state that the harvest centre should aim at collecting one or more units of autologous blood for transfusion to the donor during or after the harvest procedure.^{3, 4} However, the results of the present study show that only in few donors, if in any, the Hb concentration after the marrow harvest decreases to levels considered detrimental to healthy persons, regardless of whether an autologous transfusion is given or not.

A donation of an autologous blood unit (or several units) before the BM harvest requires the harvest to be performed during the following 2–5 weeks, because the decrease in the Hb level after an autologous blood donation should be compensated before the marrow collection, and, on the other hand, CPDA-1 whole-blood bags can be stored only for 35 days. An autologous blood unit was not drawn from 14.5% of our sibling donors at the time of the medical evaluation, because there was uncertainty of the date of BMT or the time interval was too short or too long. An autologous blood unit was not drawn from only 0.9% of the unrelated donors donating for the first time because of the timing between the medical evaluation and BMT. This reflects the practice of our centre to call an unrelated BM donor to the medical evaluation strictly 2–5 weeks before the fixed BMT date.

In all, 84% of the female and 76% of the male donors were autotransfused. The proportion of autotransfused donors in the present study is slightly lower than it has been in some previous studies among unrelated or family member donors, 90–93%.^{5, 6, 7} In the present study, only 23% of the marrow harvests were performed from unrelated donors and 77% from sibling donors. Transfusion of autologous blood may more often be carried out among unrelated than among sibling donors, because the timing between the medical evaluation and operation has to be more fixed in BM harvests from unrelated than from sibling donors.

In the present autotransfused donors, the Hb concentrations were significantly lower on the day before the BM harvest than in the donors not autotransfused. In line with our results, in a randomised study by Billote et al,⁸ the patients undergoing unilateral primary total hip replacement, who had donated autologous blood at least 2 weeks prior to surgery, showed lower Hb levels both at the time of admission and in the recovery room than those who had not donated autologous blood. Except one of the hip replacement patients, all the others who were autotransfused received their blood transfusion only postoperatively. None of the 96 total hip replacement patients required an allogeneic transfusion.

On the morning following the harvest, the Hb concentrations in the present BM donors were higher in the donors autotransfused than in those not autotransfused. The higher volumes of crystalloids infused to the donors not autotransfused than those given to the autotransfused donors may at least partly explain the difference seen in the post-donation Hb levels. However, only 0.5 and 2% of the donors autotransfused and not autotransfused, respectively, had an Hb concentration <85 g/l. No donor had an Hb level <75 g/l. Billote et al⁸ used an Hb level <70 g/l as the transfusion trigger for healthy total hip replacement patients and <80 g/l for patients with a major comorbid disease if there were no clinical signs of reduced oxygen-carrying capacity. In a multi-institutional, prospective, randomised study by Hebert et al,⁹ it was shown that a transfusion threshold as low as 70 g/l was as safe as a higher threshold of 100 g/l in critically ill patients, with the possible exception of patients with acute myocardial infarction. Healthy humans can tolerate acute normovolemic anaemia to 50 g/l without signs of tissue hypoxia¹⁰ by compensating the decrease in the Hb level with the increase of the cardiac output.^{11, 12} In recent years, the trigger for blood transfusion has shifted from a fixed Hb level to the level of Hb necessary to meet the tissue oxygen demands of the patient.¹² All BM donors have undergone a medical evaluation and probably tolerate Hb levels of 70–80 g/l.

Marrow was harvested with small aspirations from the present donors. The mean and maximal total volumes collected from the sibling donors were 850 and 1350 ml. The mean volume of marrow harvested from the unrelated donors was 930 ml and the maximal volume 1200 ml. In the study of Gandini et al,⁶ the mean and maximal volumes of marrow collected from 103 unrelated donors were 1110 and 1650 ml, respectively. The median and maximal volumes collected from 493 unrelated donors in the National Marrow Donor Program were 1050 and 2983 ml, respectively.⁵ Small aspirates of BM have been shown to contain abundantly nucleated cells and CFU-GM,¹³ and the harvesting of marrow with approximately 3 ml aspirates from the present donors has contributed to the moderate total volumes harvested. In retrospective studies of blood transfusions to BM donors, it has been shown that the number of transfusions has correlated with the volume of marrow harvested and with the second BM collections.^{14, 15} The vast majority (92%) of the donors in the present study with a post-donation Hb <90 g/l were females, many of them weighing <60 kg and with a pre-donation Hb just below the normal range. The small aspiration volumes may benefit especially small female donors who are at the greatest risk for low post-donation Hb levels. A transfusion of an autologous blood unit does not seem to prevent the decrease in the Hb concentration in small female donors after the harvest. It has been calculated that moderate blood losses perioperatively result in lower post-operative haematocrit values in surgical patients who have preoperatively donated autologous blood compared to patients who have not donated autologous blood.^{16, 17}

The present study shows that it is not necessary to collect autologous blood from healthy BM donors before the marrow harvest. The post-donation Hb concentrations do not decrease to levels considered detrimental to healthy persons whether autologous blood is transfused or not. Routine collection of autologous blood prior to BM harvest may lead to the wasting of blood. Small aspiration volumes of marrow guarantee that sufficient amounts of nucleated cells can be obtained with moderate total volumes.

References

References

1.	Thomas MJG, Gillon J & Desmond MJ. Preoperative autologous donation. Consensus Conference on autologous transfusion. Transfusion 1996; 36: 633−639. | Article | PubMed | ChemPort |
2.	Schmitz N, Beksac M & Hasenclever D et al.. Transplantation of mobilized peripheral blood cells to HLA-identical siblings with standard-risk leukemia. Blood 2002; 100: 761−767. | Article | PubMed | ChemPort |
3.	Goldman JM & for the WMDA Executive Committee. A special report: bone marrow transplants using volunteer donors − recommendations and requirements for a standardized practice throughout the world − 1994 update. Blood 1994; 84: 2833−2839. | PubMed | ChemPort |
4.	Cleaver SA, Warren P & Kern M et al.. Donor work-up and transport of bone marrow − recommendations and requirements for a standardized practice throughout the world from the donor registries and quality assurance working groups of the World Marrow Donor Association (WMDA). Bone Marrow Transplant 1997; 20: 621−629. | Article | PubMed | ChemPort |
5.	Stroncek DF, Holland PV & Bartch G et al.. Experiences of the first 493 unrelated marrow donors in the National Marrow Donor Program. Blood 1993; 81: 1940−1946. | PubMed | ChemPort |
6.	Gandini A, Roata C & Franchini M et al.. Unrelated donor transplants. Unrelated allogeneic bone marrow donation: short- and long-term follow-up of 103 consecutive volunteer donors. Bone Marrow Transplant 2001; 28: 369−374. | Article | PubMed | ChemPort |
7.	Rowley SD, Donaldson G & Lilleby K et al.. Experiences of donors enrolled in a randomized study of allogeneic bone marrow or peripheral blood stem cell transplantation. Blood 2001; 97: 2541−2548. | Article | PubMed | ChemPort |
8.	Billote DB, Glisson SN, Green D & Wixson RL. A prospective, randomized study of preoperative autologous donation for hip replacement surgery. J Bone Joint Surg Am 2002; 84-A: 1299−1304. | PubMed |
9.	Hebert PC, Wells G & Blajchman MA et al.. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. N Engl J Med 1999; 340: 409−417. | Article | PubMed | ISI | ChemPort |
10.	Weiskopf RB, Viele MK & Feiner J et al.. Human cardiovascular and metabolic response to acute, severe isovolemic anemia. JAMA 1998; 279: 217−221. | Article | PubMed | ChemPort |
11.	Greenburg AG. Pathophysiology of anemia. Am J Med 1996; 101 Suppl. 2A: 7S−11S. | Article | PubMed | ChemPort |
12.	McFarland JG. Perioperative blood transfusions: indications and options. Chest 1999; 115 Suppl.: 113S−121S. | Article | PubMed | ChemPort |
13.	Batini D, Marui M & Pavleti Z et al.. Relationship between differing volumes of bone marrow aspirates and their cellular composition. Bone Marrow Transplant 1990; 6: 103−107. | PubMed |
14.	Thompson HW & McCullough J. Use of blood components containing red cells by donors of allogeneic bone marrow. Transfusion 1986; 26: 98−100. | Article | PubMed | ChemPort |
15.	Stroncek DF, McGlave P, Ramsay N & McCullough J. Effects on donors of second bone marrow collections. Transfusion 1991; 31: 819−822. | Article | PubMed | ChemPort |
16.	Cohen JA & Brecher ME. Preoperative autologous blood donation: benefit or detriment? A mathematical analysis. Transfusion 1995; 35: 640−644. | Article | PubMed | ChemPort |
17.	Goodnough LT, Brecher ME, Kanter MH & AuBuchon JP. Medical progress: transfusion medicine (second of two parts) − blood conservation. N Engl J Med 1999; 340: 525−533. | Article | PubMed | ChemPort |