Medical Drones: High Hopes, Grounded in Science
While online retailers experiment with drones as a way to swiftly deliver consumer purchases, laboratory medicine physicians and scientists have a lifesaving goal: using drones to rapidly deliver laboratory specimens. Like any innovation put to medical use, drone technology can’t take off without clear evidence that it works—in this case, that specimens can remain stable during a drone flight and arrive at the laboratory intact for analysis.
Mayo Clinic researchers are providing that scientific grounding. James Hernandez, M.D., a pathologist at Mayo Clinic in Scottsdale, Arizona, and Christine Snozek, Ph.D., Director of Clinical Chemistry at Mayo’s campus in Arizona, played key roles in a recent study of medical drones. The study helped set a new delivery distance record for medical drones, successfully transporting blood samples for 3 hours over 258 kilometers (roughly 160 miles) of Arizona desert.
“I can see drones being used in a situation where transportation is difficult—rural areas without good roads, military zones where people need blood or blood products fast, or even in places that experience natural disasters, such as Hurricane Harvey or Hurricane Katrina,” Dr. Hernandez says.
The scientist at the forefront of medical-drone research agrees. “Drone technology offers the potential for faster and possibly cheaper services to many communities where access is challenging,” says Timothy Amukele, M.D., Ph.D., a pathologist at the Johns Hopkins University School of Medicine and leader of the long-distance study in Arizona. “The most striking example I’ve seen involves two hospitals that are located across a highway from each other, yet driving from one to the other takes 30 minutes. A drone flight would take minutes.”
Obtaining Rigorous Analysis
Dr. Amukele’s experiment required precise analysis of blood samples to determine how drone flights might affect them.
“I wanted to go with a lab whose quality I trusted. Mayo Medical Laboratories (MML) is number one in the United States in my mind,” Dr. Amukele says. “It was an easy choice.”
Dr. Amukele and his drone engineer, Jeff Street, were also familiar with MML’s work in quality process improvements, including the lab’s use of the Lean and Six Sigma systems.
In previous studies, Dr. Amukele and colleagues demonstrated that biological samples could be transported by drone over short distances. The flights covered only up to 40 km (25 miles), lasted up to 40 minutes, and were done in areas with moderate ambient temperatures. Those proof-of-concept studies weren’t sufficient to address real-world drone networks.
The three-hour experiment, which also involved researchers from the University of Arizona, was done in ambient temperatures of about 32 degrees C (89.6 degrees F). There were 21 adult volunteers who provided 4 blood samples each—a total of 84 samples. Half of the samples were driven to a flight field and held stationary; the other half were flown in a specially designed cooling box attached to a drone. Hematology and chemistry tests were performed at Mayo Clinic’s laboratories in Scottsdale, and the results of flown and stationary samples were compared using several statistical approaches.
The results for the flown and stationary samples were similar for 17 of 19 tests. The outliers were glucose and potassium, where small—but statistically significant—differences were seen.
“After blood samples are taken, the cellular components of blood—for example, white blood cells—continue to consume glucose. If you don’t remove the liquid components of blood from the cell components in a timely fashion, the glucose level is decreased from its original level,” Dr. Snozek says. “Potassium is somewhat similar. If the blood cells aren’t removed from the sample quickly enough, the potassium level is changed.”
Refining for Real-World Conditions
The glucose and potassium test results indicate a need to further refine temperature control in the drone’s flight compartment. However, Dr. Amukele notes that the samples transported by drone were generally more stable than those left stationary in an air-conditioned car.
“This experiment showed us that medical drone flights can cover greater distances than we thought. That matters because health centers have expressed a desire for drone transportation that can go 100 km or 160 km,” he says.
“This experiment also showed us something we had expected but hadn’t yet proved—flight conditions matter a great deal. In our previous experiments, shorter flights in moderate ambient temperatures didn’t seem to affect the samples,” Dr. Amukele says.
The Mayo Clinic researchers worked closely with Dr. Amukele’s team to design the long-distance study. “They listened very carefully when we raised concerns about the effects of temperature and humidity on the samples,” Dr. Snozek says.
“There were plenty of things we hadn’t thought of, such as exactly what tests we wanted to run on the specimens,” Dr. Amukele adds. “We had many conversations about the details of the study. The packing of the samples was key because lab specimens are potential biohazards. Our specimens were triple-packed to meet the standards for specimens flown on an airplane. All of these details were important for safety and for rigorous validation of our test results.”
What’s on the Horizon?
Dr. Amukele hopes next to experiment with medical-drone flights in a cold climate. Although nothing is yet planned, he and the Mayo Clinic researchers say they would like to work together again.
“It’s a great match,” Dr. Hernandez says. “Dr. Amukele understands the importance of validation, and Mayo Medical Laboratories leads the country in attention to detail for validation.
This is an exciting time for thinking about how we can best serve patients, and Mayo Clinic is open to innovation. But we have to pay attention to the evidence and validate these innovations.”
*Amukele TK, et al. Drone transport of chemistry and hematology samples over long distances. American Journal of Clinical Pathology. 2017;148:427.