Utility of temperature‐sensitive indicators for temperature monitoring of red‐blood‐cell units

BACKGROUND AND OBJECTIVES: The 30-min rule has been used to maintain a core temperature (CT) of red-blood-cell (RBC) units below 10°C during transportation. We evaluated the utility of temperature-sensitive indicators (TIs) to monitor the surface temperature (ST) of RBC units and to explore whether TIs can help with compliance with the 30-min rule by extrapolating or correlating temperature change with time. MATERIALS AND METHODS: Two US FDA-approved TIs, Safe-T-Vue 10 (STV10; Temptime Corporation, Morris Plains, NJ, USA) and Timestrip Blood Temp 10 (BT10; Timestrip UK Ltd, Cambridge, UK), were attached to 50 RBC units. After issue, their colour change indicating 10°C was monitored, and temperature excursions were measured by standard reading. In additional 18 RBC units, both ST and CT were monitored simultaneously. RESULTS: In 50 RBC units, 94% of STV10 and 100% of BT10 showed colour change indicating 10°C within 30 min; 4% of STV10 and 18% of BT10 showed it during transportation. The time for colour change indicating 10°C differed significantly between STV10 and BT10 (19·0 vs. 5·6 min, P < 0·001). In additional 18 RBC units, 83·3% of STV10, 100% of BT10 and 88·9% of CT reached 10°C within 30 min, and the time for colour change indicating 10°C was 24·4 min in STV10, 14·6 min in BT 10 and 24·2 min in CT (P < 0·001). CONCLUSION: In two TIs, the time for colour change indicating 10°C varied considerably. To enhance the utility of TIs, further improvement and standardization would be needed.