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.