Evaluation of the red cell storage lesion after irradiation in filtered packed red cell units

Packed red cell units (n = 10) were filtered and divided equally. One-half unit from each donor was irradiated (x) (3500 cGy). On Days 0, 14, 28, and 42, ATP, K+, Na+, lactate dehydrogenase (LDH), plasma-free hemoglobin (PFH), and pH were determined. The reduction in ATP was greater in the irradiated than the nonirradiated (y) units by Day 42 (mean x-y: -70, p = 0.0005). The increase in K+ was greater in the irradiated than nonirradiated units on Days 14, 28, and 42 (mean x-y: 17-20, p = 0.0001). Decrease in pH and increases in LDH and PFH were significant (p less than 0.05) on Day 42 only. K+ increases added only 1.7 to 2.0 mmol per unit, a difference felt to be clinically insignificant. The changes noted in ATP, pH, LDH, and PFH are significant but minimal on Day 42 and imply that viability changes would also be minimal. These biochemical data support the storage of irradiated units for at least 28 days.