Temperature mapping in an air ambulance helicopter: Implications for the delivery of pre-hospital transfusion

BACKGROUND: Pre-hospital blood products, including freeze-dried plasma, are increasingly carried on air ambulance helicopters. The purpose of this study was to map the temperatures within a civilian air ambulance and consider the implications for pre-hospital transfusion.

MATERIALS AND METHODS: We conducted a single-site prospective observational study in the United Kingdom. Tinytag temperature data-loggers (Gemini, UK) were secured on to three locations throughout an air ambulance, and one was placed inside an insulated drug-pouch. Temperatures were monitored at 5-min intervals. Data were downloaded monthly and processed using R and MKT software to collate maximum, minimum, and day/night mean kinetic temperatures (MKTs). Blood was transported in Crēdo ProMed 4 containers (Peli Products, S.L.U) and monitored with QTA data-loggers (Tridentify, Sweden).

RESULTS: A total of 344,844 temperature recordings were made on 302 days during a 12-month period from January 2019. The external ambient temperatures varied seasonally from -7.1°C to 31.2°C, whereas internal temperatures ranged from -0.3°C to 60.6°C. The warmest area was alongside the left front-crew position (range 1.9-60.6°C, MKT 24.8°C). The lowest daytime MKT (16.9°C) and range (1.7°C-36.4°C) were recorded next to the patient stretcher. Temperatures ranged from 4.2°C to 40.1°C inside the insulated drugs-pouch, exceeding 25°C on 47 days (15%) and falling below 15°C on 192 days (63%) In contrast, thermally packed blood maintained a range of 2-6°C.

CONCLUSION: The temperatures within an air ambulance varied throughout the cabin and often exceeded the external ambient temperature. Appropriately selected thermal protection and monitoring is required for the successful delivery of pre-hospital transfusion, even in a temperate climate.