High altitude arterialised capillary earlobe blood gas measurement using the Abbott i-STAT.

Introduction: Measurement of physiological parameters in extreme environments is essential to advancing knowledge, prophylaxis and treatment of altitude sickness. Point-of-care testing facilitates investigation in non-specialist and remote settings, as well as becoming increasingly popular at the bedside for real-time results in the clinical environment. Arterialised capillary earlobe blood gases are recommended as a valid alternative to arterial sampling in research. This study aimed to test the feasibility of obtaining and analysing daily earlobe samples at high altitude.

Methods: From 17 to 24 January 2016, 24 participants on a research expedition to Ecuador underwent daily earlobe blood gas measurements including pH, partial pressure of oxygen and partial pressure of carbon dioxide to 5043 m. Samples were analysed using an Abbott i-STAT blood gas analyser and G3+ cartridges.

Results: Daily measurements were successfully obtained and analysed at the point of care in 23/24 participants and were well tolerated with no adverse events. 12% (27/220) cartridges failed and required repeat sampling.

Conclusions: Daily earlobe blood gas analysis using the Abbott i-STAT is feasible in a protected environment at high altitude. Participants and equipment should be kept warm before and during testing. Spare cartridges should be available. This methodology may be useful for both research and therapeutic measurements in remote, rural and wilderness medicine.