By Lori Solomon, Editor, Diagnostic Testing & Emerging Technologies
Unmanned Aerial Systems (UAS or drones) could potentially be used to transport clinical laboratory specimens. Transportation of laboratory specimens via small UASs does not affect the accuracy of routine chemistry, hematology, and coagulation test results, according to a study published online July 29 in PLOS One. However, drone transport results in slightly poorer precision for some analytes, the study found.
Recent advances in sensor technology have “greatly expanded” the availability and potential uses of drones for the routine transport of small goods. In both high- and low-resource environments the majority of clinical laboratory specimens are obtained in physician offices or clinics and transported to larger, more complex laboratories for analysis. UAS, the authors say, have advantages over other transport vehicles, including not being subject to traffic delays, low overhead costs, “and the ability to go where there is no passable road.”
Given that few tests account for the majority of test volume, the researchers focused on 33 of the most common tests performed in hospital laboratories. Three paired phlebotomy samples were obtained from 56 adult volunteers (336 samples total; two 3.5 mL serum separator tubes, two 3 mL Potassium EDTA whole blood tubes, and two 2.7 mL citrated plasma tubes). One set of tubes from each patient (n=168 samples) were driven to the flight field and held, while the other 168 samples in the paired set were flown in the UAS (flight time range, 6 to 38 minutes). The samples were packed (in custom-cut soft foam, sealed in two flexible biohazard bags with absorbent material, and then placed inside a fuselage constructed of impact absorbing EPS foam) to control the in-flight environment and to contain the samples in the “unlikely event” of a leak or breakage.
After the flight, 33 of the most common chemistry, hematology, and coagulation tests were performed. The time from the first drawn sample to the last result was less than 8 hours for all 336 samples. Four separate performance acceptability criteria (including two from groups outside the United States) were used to assess results.
The researchers found that test results from flown and stationary sample pairs were similar for all 33 analytes. For 26 tests, the results from the flown and stationary sample pairs were within 5 percent of each other. Only bicarbonate did not meet the strictest (Royal College of Pathologists of Australasia Quality Assurance Program) performance criteria, which the authors say was due to poor precision rather than bias. The overall concordance, based on clinical stratification of normal versus abnormal test results was 97 percent and for normal samples agreement was 99 percent. Length of flight had no impact on results.
“A few analytes; namely, Chloride, CO2, MCV, MCH, Basophil %, Eosinopil, and partial Thromboplastin time (aPTT) had a 95% limit of agreement greater than 10%,” the authors, led by Timothy K. Amukele, from Johns Hopkins University in Baltimore, Md., acknowledge. “However these analytes had low mean levels (Eosinophil and Basophil), high variability (CO2 and Monocytes), or were based on transformed data (aPTT ratio).”
The authors add that the study’s most significant limitation was that the volunteers were mostly healthy individuals, so their results were in the relatively narrow normal range, rather than spread across the full assay range.
Several authors report financial ties to the aeronautics industry.