On a hot afternoon in late September 2016 the Johns Hopkins Medical Drones team drove to a flight field in the Arizona desert with 40 vacutainer tubes filled with human blood obtained from volunteers. The individually wrapped tubes sat in two custom-designed white plastic cooler boxes which had wires coming out of one end, ventilation holes at the other, and ran off the drone’s battery power. We carefully placed one of the boxes on the drone, stood back, and flew the samples around for 260 kilometers in what seemed like an unending series of concentric circles. Great. But why would doctors be involved in this exercise?
For the last 3 years, the Johns Hopkins medical drones team has examined the stability of human samples transported via drone. Our approach has been similar for each study. Get two sets of samples, fly one on the drone, then take both sample sets back to laboratory for analysis to see if there are any changes. However, until this study in Arizona we had only flown these samples up to about 40km, in mild weather, and for up to 40 minutes at a time. A request to set up a drone network in a flood-prone area of a country in Southwestern Africa made us realize that we needed to repeat the stability tests in warmer weather and for longer flights. This drone network would serve clinics that were up to 50 km away from each other, therefore requiring round-trips of at least 100km. Once we received this request it became clear pretty quickly that our previous tests flying for to 40km were not good enough for an aircraft that would have to fly in a hot environment between several clinics that were each 50km away from each other.
After the 3-hour 260km flight, we took both sets of samples back to the Mayo Clinic laboratories in Scottsdale, Arizona and performed 19 different tests on the samples. Each pair of samples was compared to check for differences between the flown and not-flown sample sets. Although results from sample pairs were similar for 17 of the 19 tests, small differences were seen in Glucose and Potassium, which do also vary in other transport methods. We suspect the differences seen in this test arose because the not-flown samples were not as carefully temperature controlled as the flown samples in the temperature-controlled chamber. This study (which is the longest flight of human samples on a drone to date) shows that drones can be used for blood samples even for long flights in hot conditions. However, the temperature and other environmental variables must be well-controlled to keep the blood stable.
-Dr. Timothy Amukele is an Assistant professor in the Department of Pathology at the Johns Hopkins School of Medicine and the Director of Clinical Laboratories at Johns Hopkins Bayview Hospital. He is also the Medical Director of two international research laboratories in Uganda and Malawi. He has pioneered the use of unmanned aerial systems (colloquially known as drones) to move clinical laboratory samples.
-Jeff Street is an unmanned systems engineer and pilot at the Johns Hopkins School of Medicine with more than 10 years of experience in the development of new and innovative vehicles. He is leading the Johns Hopkins aircraft development efforts for a wide range of medical cargo applications.