Correspondence

Submission of Correspondence

Transfusion welcomes correspondence items, which, found suitable, will be published as space permits. In general. please follow rhese instructions:

Typing: Double space, plain bond paper, in duplicate. Format: As seen in currenr Ierters in Transfusion (the typist should consult a copy of the journal). Length: Not more than 2 typewritten pages. References: Not more than 5 (same format as Transfusion). Tables and figures: Not more than 2 in all (may be one of each), in Transfusion format. Accompanying letter: Correspondence items should be accompanied by a Ierrer signed by all the authors.

These instructions should make it easier topreparecorrespondenceand, in turn. speeduppublication. Letters will be returned to the sender they are nor in the appropriate format.

We encourage you to continue to use the Correspondence Section for your own observations. for contention with our regular articles, vyou feel so moved, or for submitting technical or medical questions. Short presentations that are more elaborate than allowed for in the above instructions may be submitted as Brief Reports.

Submit letters to: Douglas W . Huestis, M.D., Department of Pathology, University of Arizona College of Medicine, Tucson, AZ 85724.

Platelet Concentrate Storage at 2 2 O C

To the Editor: Two recent reports'.' indicate that platelet concentrates

(PC) can be stored successfully for 5 days at 22°C. Therefore, the article by Lazarus et al.' suggesting that storage be limited to 24 hours came as a shock. One interpretation of their poor results with storage of random donor PC for 24 to 72 hours would be that a n unusually high percentage of the PC had low pH (G6.0) after storage. Current regulations limit this percentage to 25 percent.

The authors report:

Storage Number Interval of Mean (Hours) Studies PH SEM SD'

24-48 21 6.7 0.4 1 .a3 48-72 i a 6.6 0.3 1.27

my calculation, SD = SEM x ,hi- The use of mean and S E M suggests that the values for pH

were normally distributed. If so, 35 and 32 percent of PC had pH G6.0 at 24 to 48 and 48 to 72 hours, respectively. Because of rounding in reporting of mean pH and SEM, these calculated percentages could be subject to an error of f 3 percent, but all possible calculations are greater than 25 percent.

Furthermore, since 15 patients were each infused with 6 units of PC, 90 units were infused at 24 to48 hours and 48 to 72 hours. The 21 and 18 units of PC sampled for .pH measurement may not have representative of the units actually infused.

The incidence of significant pH fall is reduced markedly in the containers recently made The experience of Lazarus et al.> with storage for 24 to 72 hours is not typical of the results which can now be achieved.

SCOTT MURPHY, M.D. Cardeza Foundation for Hematologic Research

Philadelphia, P A I91 07

References I . Murphy S. Holme S. Improved platelet preservation in a new

container [Abstract]. Transfusion 1980:20624. 2. Murphy S. Simon T. Characteristics of prolonged platelet

storage in a new container [Abstract]. Transfusion 19XI:21:

3. L.a/arus H M . Hewig RH. Warm SE. Finhman DJ. Transfusion experience with platelet concentrates stored for 24 to 72 hours at 22OC. Importance of storage time. Transfusion 1982;22:39-43.

637-8.

The foregoing letter was sent to Dr. Lazarus, who replied as follows:

To the Editor: Dr. Murphy proposes that the variable response to

platelet concentrates stored for periods longer than 24 hours, which we reported, may be an effect of reduced pH.' We measured pH on 39 individual units and 20 pooled concentrates stored for greater than 24 hours, and the values conformed to established standards.2 Although the pH was not measured on all units, only rarely wasa unit encountered in which the pH was less than 6.0. These units were not transfused. Dr. Murphy calculated that 32 to 35 percent of the concentrates had a pH of less than 6.0 on theoretical grounds. I t is not likely that the percentage of unsatisfactory platelet concentrates could be this high, since one must postulate that all the abnormal units were the ones in which pH was not measured.

The platelets transfused were normal in in vitro tests of morphology and function. We postulated that subtle abnormalities undetected by these tests occurred in platelets during storage, which become important in patients who have been transfused extensively. Dr. Murphy reports that the new containers (Fenwal PL-732 ) maintain adequate pH for 5 days, and provide platelets which survive normally in vivo.' These studies were performed in normal persons. Although recently we have had limited experience with platelets stored in these containers and can report acceptable results, the recipients were not extensively transfused.

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