BACKGROUND: The 30-minute rule, whereby intact red blood cell (RBC) products may be returned to stock if returned to 4°C storage within 30 minutes of issue, was established many years ago. It was based on observations that the core temperature of units of whole blood removed from storage temperatures of 1 to 6°C, and left at room temperature, would reach 10°C at between 45 minutes and 1 hour.
STUDY DESIGN AND METHODS: Forty-one units of RBCs resuspended leukoreduced and 8 units of pediatric RBCs resuspended leukoreduced were exposed to ambient temperature for periods of time between 0 and 60 minutes. Core temperatures of all units were measured at 1-minute or 5-minute intervals.
RESULTS: Resuspended RBCs units reached a mean core temperature of 10°C at 15 minutes, 12.7°C at 30 minutes, and 15°C at 60 minutes. Pediatric RBCs reached a mean core temperature of 12.8°C at 15 minutes, 15.5°C at 30 minutes, and 17.8°C at 60 minutes.
CONCLUSION: In view of our results, and the range of RBC products now available, it may be timely for blood services to review and reduce the 30-minute rule.