Introduction: Very often pRBC units remain at room temperature, not only to warm up before its use, but also when the cold chain is broken due to technical refrigerator problems or unexpected longer shipping times. High temperature exposures have been related to early red blood cell (RBC) destruction and microbe contamination and proliferation. To the best of the authors’ knowledge, no veterinary studies addressed haemolysis and bacterial contamination in pRBC units during long room temperature exposure periods.

Objective: This prospective study aimed to evaluate the haemolysis and bacterial contamination in pRBC units stored at room temperature (20–22°C) for 5 days.

Methods: After processing, 13 pRBC units were evaluated for haemolysis (HemoCue® Hb and Plasma Low Hb determinations) and aerobic bacterial contamination (Biomerieux® aerobic culture media) at T0. Six 20 ml samples were aseptically prepared from each pRBC unit, using sterile connections to paediatric transfer blood bags specific designed for blood storage (Fresenius Kabi®). This allowed for single determinations of each sample, decreasing the repeated manipulation deleterious effect on RBCs. Haemolysis and blood cultures were evaluated after 4 hours (T1), 8 hours (T2), 12 hours (T3), 24 hours (T4), 48 hours (T5) and 120 hours (T6). Samples were kept at room temperature 20–22°C.

Results: At T0 a mean haemolysis of 0.12% (SD 0.06) was calculated. The value had a linear increase, with 0.15% (SD 0.05); 0.16% (SD 0.05); 0.17% (SD 0.05); 0.19% (SD 0.05); 0.22% (SD 0.03); and 0.30% (SD 0.04) at T1, T2, T3, T4, T5 and T6, respectively. All cultures tested negative.

Discussion/Conclusion: According to the human blood banking guidelines, a maximum 0.8% haemolysis is recommended. Our determined values, that showed a gradual but slight increase in haemolysis, along with negative blood cultures, confirmed the relative low impact of the exposure to room temperature on aseptically prepared fresh units. This study helps to clarify the evolution of haemolysis in pRBC units kept at room temperature, thus avoiding unnecessary wastes when the cold chain is broken. However, the authors emphasize the need for quality control analyses to ensure the safety of its use.