Buffering and dilution in red blood cell storage

BACKGROUND

Red blood cell (RBC) storage solutions work in a narrow pH range between 7.2 and 6.4. While keeping RBC within that pH range, ATP production can be increased by buffering or dilution.

STUDY DESIGN AND METHODS

In the first study, 12 units of packed CP2D RBCs were pooled in groups of four, re-aliquoted, and added to one of four additive solutions (ASs): AS-3, 110 mL; EAS-61, 170 mL; EAS-78, 170 mL; or EAS-81, 110 mL. EAS-78 and -81 contain bicarbonate. Units were sampled approximately weekly for 10 weeks for biochemical measures. In the second study, 12 volunteers donated RBCs for measures of (51)Cr in vivo recovery after 6 or 8 weeks of storage in EAS-81.

RESULTS

RBCs stored in the higher-volume or buffered ASs had higher RBC ATP concentrations. The combination had an additive effect. Hemolysis was reduced in dilute ASs and less so with buffering. RBCs stored for 8 weeks (n=6) in EAS-81 exhibited 87+/- 2 percent 24-hour (51)Cr in vivo recovery and 0.4+/- 0.2 percent hemolysis.

CONCLUSIONS

It is possible to store RBCs for 8 weeks in buffered conventional volume ASs. Combining buffering and increased AS volume improves stored RBC characteristics further.

Technetium-99m hexamethylpropyleneamineoxime labelled leucocyte scanning in the initial diagnosis of Crohn's disease

The technetium hexamethylpropyleneamineoxime labelled white cell scan (WCS) is not widely used as a screening test for Crohn's disease primarily because, though sensitive, it is perceived as being insufficiently specific. A series of 42 patients screened for Crohn's disease by this method was analysed retrospectively. The sensitivity was 100% and specificity 91%. This performance was maintained in a subgroup of these patients with very low prevalence of disease. If appropriate criteria for interpretation are used the WCS is a specific as well as a sensitive screening test for Crohn's disease.