TRANSFUSION 1985-VoI. 25. No. 3

CORRESPONDENCE 29 1

reagents that are sensitive and specific, but where rare antisera are concerned, we are limited by problems of availability of raw material. The consumer has a responsi- bility to understand and accept the limitations inherent in the performance of blood grouping tests, and to keep them in mind when interpreting test results.

MARGARET TREACY PATRICIA BONNESS

Ortho Diagnostic Systems Inc. Route 202

Raritan. NJ 08869

JOHN CASE, FIMLS Gamma Biologicals, Inc.

3700 Mangum Road Houston, TX 77092

DEBORAH WEILAND. MS, MT(ASCP)SBB AMIRAM DANIEL PHD

Cooper Biomedical. Inc. One Technology Court

Malvern. PA 19355

SUSAN ROLIH. MS. MT(ASCP)SBB RALPH EATZ

Immucor. Inc. 3130 Gatewqv Drive Norcross, GA 30071

CHARLA ISSITT, MS, MT(ASCP)SBB JAMES KELLER

Dade Diagnostics, Inc. P. 0. Box 520672 Miami, FL 33152

Implications of transfusion of "undercollected" units

To the Editor: Davey et al. ' recently documented that packed red cell

units produced from donations of 275 ml whole blood into 63 ml of citrate-phosphatedextrose-adenine (CPDA-I) had acceptable posttransfusion survivals. These workers pre- dicted that use of these "undercollected" units would expand

the nation's available blood supply by 0.75 to 1.5 percent (82,500-161,700 units annually).

However concern may be expressed about the clinical effects of an "undcrcol1ected"unit. Would the transfusion of an additional unit be needed to provide the patient with the necessary increment in red cell (RBC) mass and thus increase the risk of posttransfusion hepatitis? Would the smaller increment in RBC mass be confusing to the clinician who might then suspect hemolysis or bleeding?

A mathematical approach to these considerations is presented in Table 1. The recipient was assumed to be a normovolemic, anemic patient. The results of four hypo- thetical transfusion episodes with 2 units of packed red cells are detailed. One unit in each case is derived from a phlebotomy of acceptable size under current regulations. either a "standard"450-ml phlebotomy (nominal volume) or a "small" 405-ml phlebotomy (minimum volume). An "undercollected" unit is defined as red cells derived from a 300-ml phlebotomy.

The transfusion of a single "undercollected" unit with a "standard" unit would not be clinically distinguishable from the transfusion of 2 "standard" units. Even in the situation where the least red cell mass is transfused ("small" unit + "undercollected" unit), the resulting differences in blood volume, red cell volume, and hematocrit compared with when 2 "standard"units are transfused would be within the range of random error of these measurements.*.' If the patient's transfusion episode contained additional "standard" units, any effect would be further masked. If the rate of undercollection averaged 2 percent, the chance of a patient receiving 2 undercollected units in a transfusion episode would be small: O.OOO4 in a 2-unit transfusion episode. 0.0023 in a 4-unit episode, and 0.0055 in a bunit episode.'

Utilization of "undercollected" units would make a small, but important contribution to the blood supply without involving additional expense or recruitment of new donors. Although the overall proportion of units failing to meet minimum volume standards in our region is 2.8 percent, blood drives involving many first-time donors, such as in high schools, may have a much higher rate of unsatisfactory phlebotomies (6.0 f 0.32%). Many of these units would be

Table 1. Clinical effects' of transfusion of "unciercollected" units

Combined Vol u mest Recipient: Posttransfusiont

Donation Types Donation Volumet RBCs Plasma Blood Volume RBC Volume Hematocrit (%)

Standard + 388 130 541 8 1662 30.7 Standard 450 450 1 (100) (100) (100) (100)

Standard + Small

368 123 5391 1642 30.5 405 450 1 (94.8) (94.6) (99.5) (98.8)

323 108 5331 1597 30.0 300 (83.2) (83.1) (98.4) (96.1 1

303 101 5304 1577 29.7

450 1 Standard + Undercollected

Undercollected 300 (78.1) (77.7) (97.9) (94.9)

Small +

Effects of transfusing a 70 kg male with a blood volume of 70 ml per kg (4900 ml) and an initial hematocrit of 26 percent (RBC volui:ie = 1274 ml) with packed red cells derived from 2 units of different initial volumes. Donor hematocrit assumed to be 43 percent. Packed RBC unit hematocrit taken as 75 qercent.

t All volumes in milliliters with percentages in parentheses.

292 CORRESPONDENCE

acceptable if considered as "undercollected." Utilization of this resource would seem prudent. In addition, donors of these "undercollected" units might have a more positive experience, thereby encouraging repeat donation.

Consideration should be given to the licensure of "under- col1ected"units. These units may be an important addition to the nation's blood supply without creatingclinical confusion or patient risk.

JAMES B. AUBUCHON, M D Rochester Region

American Red Cross Blood Services Rochester, New York

References

I . Davey RJ. Lenes BI.. Casper AJ. Demets DL. Adequate survival of red cells from units "undercollected" in citrate-phosphate- dextrose-adenine-one. Transfusion 1984;24:3 19- 22.

2. Nelson D A . Basic methodology. In: Henry JB. ed. Clinical diagnosis and management by laboratory methods. 16th ed. Philadelphia: WB Saunders. 1979:858-917.

3. Mollison PL. Blood transfusion in clinical medicine. 7th ed. Oxford: Blackwell, 1983.

4. Diem K, Lentner C. eds. Scientific tables. 7th ed. Ardsley. NY: Geigy Pharmaceuticals. 1970.