A pilot experimental study of cold-chain management, haemolysis and oxidative stress of packed red blood cells in early blood transfusion: toward a blood viability model in the out-of-hospital setting.

Injury and violence is a global public health concern, implicated in 4.4 million deaths annually. The most common cause of preventable death is haemorrhage in the out-of-hospital setting. Haemorrhagic shock patients are at risk of disseminated intravascular coagulation, global myocardial ischemia, and death. This risk is heightened among the young, older adults, or polytraumatised. The definitive standard of care is to stop the bleeding and to replace the lost haemoglobin whilst supplementing oxygen. There is paucity in emergency blood transfusion research in the out-of-hospital setting. It is not out-of-hospital standardised practice. This novel research conducted in Western Cape, South Africa, determined the viability of blood in transit by evaluating haemolysis and oxidative stress in Packed Red Blood Cells (PRBC) on public ambulances. A relatively new statistical method (generalised additive model with smooth term) was used to model non-linearity in the haemolysis trend. In a designed experiment, the viability of blood was determined by placing PRBC in temperature-controlled refrigerators at ambulance bases (maintained at 1-6 °C) as a 'Control'. The 'Treatment' PRBC were transported in cooler-boxes with 2 eutectics (icepacks). The cold-chain was monitored against the recommended transportation temperature range of 1-10˚C. The PRBC was assessed weekly for haemolysis and at the end of the study for lipid peroxidation, both threats to PRBC viability following environmental exposure (to transit temperatures and movement). The PRBC placed on ambulances indicated that they were < 0.8% haemolysis threshold after day 35. Three packs in the treatment group were > 0.8% on day 42, along with one in the control group (which was deemed an outlier). Transported PRBC remained between 1-10˚C for the most part. Conjugated dienes and thiobarbituric acid reactive substances showed no statistically significant changes and aligned with colorimetric assessment. The blood viability on ambulances remained within the acceptable ≤ 0.8% haemolysis level until the PRBC expiry, on day 42. PRBC remained within the transportation temperature reference range for South Africa and no significant oxidative stress or cellular degradation was documented. This evidence supports PRBC viability when transported in ambulances conditional to the use of eutectics in closed cooler boxes and has relevance in low- and middle-income countries or in humanitarian contexts.