A significant benefit of telemedicine is its ability to bring care to those who might otherwise have difficulty getting it, such as individuals with limited mobility in remote areas. A limitation of telemedicine as offered in many settings is its heavy reliance on history and limited physical examination, without access to lab data or diagnostic images. Consider, for example, all the criticisms leveled at distance care providers, especially in the direct-to-patient model, respecting their management of suspected UTIs. The critics point out that there is often no very easy way to obtain a urine sample, either for analysis or for culture.
One partial solution to that problem might be mobile technicians, such as phlebotomists, who can be sent to the patient’s location. In 2017, however, a new possible solution presents itself: drone sample transport.
In a current paper, Amukele and colleagues assessed “the stability of biological samples in prolonged drone flights by obtaining paired chemistry and hematology samples from 21 adult volunteers in a single phlebotomy event—84 samples total.” Timothy K. Amukele, James Hernandez, Christine L.H. Snozek, et al., “Drone Transport of Chemistry and Hematology Samples Over Long Distances,” American Journal of Clinical Pathology (5 Sept. 2017), https://academic.oup.com/ajcp/article/doi/10.1093/ajcp/aqx090/4104555/Drone-Transport-of-Chemistry-and-Hematology?guestAccessKey=92d16852-e806-4992-80c9-fc57118974f7&utm_source=STAT+Newsletters&utm_campaign=ec12d9db57-MR&utm_medium=email&utm_term=0_8cab1d7961-ec12d9db57-149636301. Although studies of drone sample transport have been done before, the authors deemed the pertinent experimental conditions to be too far removed from real-world situations to permit valid conclusions. In particular, previous studies had not exposed samples to high temperatures or prolonged transports. In the Amukele study, subjects’ specimens were flown at high ambient temperatures and low humidity, over a relatively protracted period.
According to the abstract, “Half of the samples were held stationary, while the other samples were flown for 3 hours (258 km) [160.3 miles] in a custom active cooling box mounted on the drone. After the flight, 19 chemistry and hematology tests were performed.” Results were encouraging. Of 19 analytes, 17 produced results substantially similar to those in the control (stationary) group. The 95% intervals for sample pairs in the study met the four clinical and/or regulatory acceptability criteria the authors applied.
Results for glucose and potassium in flown samples, however, were 8% and 6.2%, respectively, higher than in the control samples. During flight, the investigators utilized a cooling device run by the drone’s battery. They theorized, however, that temperature differences between the two sample groups provided the explanation for the discrepant results. The flown samples (mean, 24.8°C) were a mean of 2.5°C cooler than the stationary samples (mean, 27.3°C) during transportation to the flight field as well as during the flight. The collaborators argue that
“The reason for this finding is that glycolysis [generating glucose by chemically splitting glycogen] is more efficient at higher temperatures. Similar patterns have been demonstrated for potassium, but the mechanisms are different. Intraerythrocyte concentrations of potassium [i.e., concentrations of potassium within red blood cells, or RBCs] are 40-fold higher than those in serum, and thus the mild changes in RBC membrane permeability that occur with increasing temperature lead to spurious increases in serum potassium levels.”
It is not obvious to your servant why this explanation fits the data. If despite use of the cooling device aboard the drone the temperature of samples on the ground exceeded those in the air, it would seem as though RBC lysis would proceed at a faster rate in the former setting than the latter. If so, it seems as if one would expect the glucose and potassium values to be higher, not lower, in the stationary specimens. Whether the authors’ theory turns out to be correct or not, however, drone transports might provide at least a partial solution to the dilemma facing a telephysician who would order lab studies if he could. With respect to “time- and temperature-sensitive analytes” such as glucose and potassium values, the authors acknowledge that using their technique “will require good preplanning and stringent environmental controls to ensure reliable results.”
There were some significant limitations to this study. First, the “n” was small (only 21 subjects), with an unexplained 2:1 female: male ratio. All subjects were healthy, so the range of values was rather narrow and close to normal. And, as noted, two important electrolytes were measured with an accuracy the investigators considered to be insufficient. Whether technology can be developed to overcome temperature differences, or any other factor that might contribute to discrepant glucose and potassium values, remains to be seen. Still, that drone technology exists, and that it can be harnessed for a rather wide array of tests requiring analysis of blood samples, suggests that drones might some day play a role in a maturing telemedicine service. It appears that the blood counts, for example, were the same in the flown and stationary samples. As to the two chemistry values with doubtful validity, it might be a mistake in this era to bet against an eventual technological fix.
Providers intrigued by this possibility do need to factor in other concerns, both practical and legal. Of the former, the most obvious is the need to obtain samples properly. Although it may be fairly straightforward to coach a lay person on how to obtain a valid urine sample, drawing blood requires phlebotomy, and thus both sterile and non-sterlie equipment and sterile technique. One could send technicians into the field, at least where the patients are not too far away, but of course that would entail additional costs. It would also implicate legal principles that have to be considered.
Whether technicians are sent or some mechanism is developed to train lay persons how to collect specimens, the Clinical Laboratory Improvements Amendments (“CLIA”), P.L. 100-578, 102 Stat. 2903, http://uscode.house.gov/statutes/pl/100/578.pdf, as amended, impose responsibility for the conduct of phlebotomists on the labs they work for. Understandably enough, CLIA in its current form makes no provision for pre-analysis services performed by the laity. CLIA Sections 493.1407(b) and 493.1407 (e)1, (e)3i, and (e)3iii provide that the laboratory is also responsible for seeing that the personnel and systems used, even in the pre-analytic phase, provide reliable test results. If a tech is an employee of the lab, that may be fine; if the tech is an independent contractor, never mind a layperson, the arrangement might be problematic.
Then too, those involved in specimen collection may well be bound by the laws governing privacy of medical records, such as HIPAA and HITECH and the many state statutes aimed at privacy protection. Specimen collectors will need to be mindful of the risks of exposure to blood-borne pathogens such as HIV and various hepatitides, addressed by OSHA standard 1910.1030.
To utilize drones for serum chemistries, then, we will need to develop a fix for the glucose and potassium problem, but we might also need to amend the law.