Evaluation of the advanced air mobility potential for organ transplantation in Austria and Germany
In addition to organ shortage, technical and logistical issues during transplantation, a major factor is time and the associated ischemic tissue damage during organ transport from donor to recipient28,29. The benefits of CIT reduction , one of the few things we can modify for any potential and specific organ donor, are proven and widely accepted30,31,32,33,34,35. Organ transplantation is a critical component of clinical care worldwide, with liver, kidney, heart, lung, pancreas, and intestine transplantation being routinely performed, and both patient and allograft survival continuing to improve36. The success of transplantation relies on various factors, including organ preservation and minimizing ischemic tissue damage during transport. The current transportation process faces challenges related to time, logistics, and technical issues. AAM technology, which has not yet been implemented in Europe for organ transports holds significant potential in addressing these challenges and optimizing the transplantation process as the transport distances of organs allow AAM aircraft to cover a substantial share. AAM aircraft are a viable option in the near to medium-term future as, even today, a substantial portion of organs are used to air transport by using helicopters and private or commercial aircraft. In the transport chain, there is often an additional ground-based segment to cover the trip from the hospital to the airport or heliport, especially when no landing site is available directly at the hospital. Regions with better connectivity to airports and heliports thus might have more transport options and, consequently, better CIT results. In the future, AAM aircraft could enhance connectivity for regions with limited airport access, offering a lower-cost alternative to helicopters. In the studied countries, Germany and Austria, substantial potential exists since each Austrian hospital has a heliport, all transplant centers in Germany are equipped with one, and nearly all German organ procurement centers have a landing site at or near their location. We explore and discuss the potential benefits of AAM in organ transplantation, including reduced CIT and overall process optimization.
The preservation of organs is a crucial aspect of the donation and transplantation process37. Ongoing research aims to improve transplantation outcomes through strategies such as machine perfusion and supplementation of preservation solutions, which are partly incorporated into the clinical routine38,39,40,41,42. However, apart from organ shortage, time and ischemic tissue damage during transportation pose significant challenges28,29. The reduction of CIT has been widely discussed and accepted in research due to its impact on graft loss risk30,31,32,33,34,35. Strategies to address these challenges are essential for improving transplantation outcomes. In our study, we estimated the organ transport ranges using a Monte Carlo simulation because the data on the Eurotransplant region was not available.
Our limited time benefit estimation indicated that there is potential for AAM vehicle to replace car-based transport in the organ transplantation context, particularly as AAM vehicle speed increases. The results obtained from this study are applicable to other car-based transports in the context of organ transplantation. In the “Methods” section, we introduced three possible AAM applications from our perspective: The transport of lab samples in the context of organ transplantations (e.g., frozen section, blood), the organ itself (plus lab samples), and the medical team (plus the organ itself and lab samples). The rationale for this structure is the availability of AAM vehicles capable of carrying the required payload. There are vehicles capable of transporting only lab samples. The next step up in payload is the organ itself, together with the lab samples. The largest relevant AAM vehicle category (not yet certified) is able to transport the medical team with the organ and the lab sample. If we introduce these vehicles in the organ transplantation context today, the overall process and organization through Eurotransplant and the coordination offices will likely remain the same initially. This means that the coordination offices send the retrieval teams to the retrieval hospital. The retrieved organ and lab samples either travel with the medical team back to their transplant center if it is allocated there, or the organ and lab samples travel independently to their specified destination transplant center. Depending on the regulatory approvals and especially technology availability, the most likely stepwise introduction process is to first test AAM technology with lab samples, then use it to transport organs, and finally, when the man-carrying AAM vehicles are proven and available to supplement the helicopter fleets, they should be introduced to healthcare.
Regarding lab samples, the potential time savings could exceed the observed mean of 21.5 min if the samples are transported independently of the organ. Currently, organs are received at the hospital in Graz, and upon arrival, the frozen section and the donor’s blood are taken to the laboratory for testing. This process results in unnecessary delays due to the time required to perform the laboratory analyses and subsequently prepare the recipient for transplantation. Samples can be shipped immediately after retrieval at the beginning of the organ procurement procedure, potentially reducing CIT by 60 min or more. This enables faster determination of the donor-recipient match, early recipient preparation, and immediate transplantation upon organ arrival. Additionally, in cases of unacceptable match results, the organ can be offered to other patients earlier, saving valuable time. However, a caveat of this approach is that a second transport would be required for the medical team if they are traveling to the same destination as the organ. For pure organ transport, the benefits extend beyond substantial time savings. There is also potential to increase flexibility in the logistics process and reduce dependence on human transport personnel. The greatest absolute time savings are achieved when transporting the medical team using AAM vehicles instead of ground-based methods. The challenge in this scenario is that AAM manufacturers must still validate their claims that these aircraft can be operated at costs comparable to taxi services. In summary, we believe the greatest potential lies in the independent transport of lab samples separate from the organ, organ transport when the medical team is not traveling to the same destination, and the transport of the entire medical team with or without the organ. The potential benefits of CIT reduction through AAM are substantial, as every hour of reduction translates to a 3.4% decrease in liver graft loss risk according to Lozanovski30. The analysis conducted highlights the need to also track the logistics process and additional timestamps (e.g., departure and arrivals, internal logistics duration) to enable a holistic data-driven assessment and impact estimation of AAM technology or other potential changes to the logistics process.
In addition to reducing transport time through faster transportation methods, there are other strategies to minimize CIT. One approach is to prioritize local recipients, thereby reducing the geographical distance between the donor and recipient, which should directly lower CIT. Eurotransplant, the organization in which this study is situated, already implements this strategy unless the case is classified as high urgency. Additionally, optimizing internal hospital processes to facilitate “just-in-sequence” surgeries could further reduce CIT. Another potential approach is the transportation of either the donor or recipient to minimize CIT. However, transporting the organ donor presents significant logistical and medical challenges, as well as ethical and legal concerns. Conversely, the transport of organ recipients occurs infrequently.
The clinicians’ behavior in organ allocation could be affected if a CIT reduction can be proven in practice by applying AAM technology. By substantially accelerating the transport process, clinicians might decide to allocate organs to farther distant recipients, which counteracts the positive effect. However, transporting organs farther could also allow for a better donor-recipient fit or cover high urgency recipients better, hence, the longer CIT might not affect the medical outcome negatively. Furthermore, machine preservation and hypercooling techniques might reduce the necessity to focus on CIT, hence, currently existing allocation algorithms need to be revisited.
Advancements in machine perfusion are expected to significantly enhance transplantation success. This technology enables a thorough evaluation of less ideal organs, such as those from circulatory death donors or extended criteria donors, thereby expanding the pool of viable organs. In the future, genetic modifications and medical treatments applied during perfusion could become feasible, which may reduce the need to minimize logistical transport time38,43. The objective of employing Advanced Air Mobility (AAM) vehicles is not just to reduce transport time but also to increase the flexibility of the logistics process and reduce dependence on transport personnel. Future AAM vehicles are anticipated to have the capability to transport perfusion machines, effectively combining two process steps into one streamlined process.
The transport process of organs, including factors such as time and distance, is not the sole determinant of CIT. Other important factors include the duration of organ procurement and transplantation procedures, internal logistics within the hospital, and waiting times for laboratory test results that assess the organ’s transplantability. However, the transport process is the only part AAM technology might be able to influence. This study uses the range of organ transportation as a proxy to estimate the proportion of organ transplantations that could potentially be supported by Advanced Air Mobility (AAM) technology. The rationale for this approach lies in the current limitations of AAM vehicles, primarily due to existing battery technology. As battery technology advances and fuel-cell-based powertrains become available, other, yet-to-be-identified factors may emerge as more suitable proxies. Additionally, every hospital in Austria, all transplant centers in Germany, and many organ procurement hospitals in Germany have at least one helipad. This infrastructure ensures direct access to air transport, eliminating the need for additional ground travel between airports and hospitals. This setup has the highest potential for routes up to 150-200 km, where automobiles are predominantly used today, aligning well with the capabilities of current AAM technology.
This study, focusing on Germany and Austria, reveals that 48% of German and 80% of Austrian organ transportation trips have a trip length of less than 150km, making them addressable by AAM in the short term. The distribution of trip lengths shows a skew towards shorter distances compared to the unweighted distribution, indicating the potential for efficient AAM application.
The unweighted distribution assumes a uniform distribution of origin and destination pairs, i.e., each organ is transported exactly once from each possible retrieval hospital to each possible transplant center. This assumption (obviously) does not reflect reality, but would be a good first estimate without additional data and information. The weighted Monte Carlo simulation result based on historical data confirms that a uniform unweighted distribution does not reflect reality and should not be used. Additionally, using it as a reference would lead to the (wrong) conclusion that in the short-term AAM technology appears unpromising as the range is substantially exceeded. Therefore, the unweighted uniform distribution serves purely as a baseline for comparison and underlines the necessity to conduct such analyses with real-world data. Eurotransplant’s allocation algorithm, which prioritizes for donor-recipient matching, taking into account medical and ethical criteria , while considering national organ exchange balance and logistical considerations, also aligns well with the simulation results. With Eurotransplant’s statistics library44, we can confirm higher urgency shares for hearts (Germany: 78%, Austria: 56%), lungs (Germany: 15%, Austria: 42%), and to some extent livers (Germany: 15%, Austria: 10%). The study also underscores the importance of shorter trips in Austria due to limited organ procurement and transplantation hospitals and the country’s mountainous geography.
AAM technology has demonstrated significant potential in healthcare14,19,22,23,45,46, including time-critical organ transplantation24,25,26. By reducing transport time, AAM can effectively reduce CIT. The range of possible destinations also expands, enabling better allocation of organs. Scalea and Sage24,25,26 used a small unmanned drone and argue that while inner-city transports show potential, transports from city-to-city or intra-regional transport by drone have even more potential and benefits. Our study assessed the potential for Germany and Austria to conduct organ transports using AAM. We find that 48% of German and 80% of Austrian transplantations fall within a trip length of 150km, making them suitable for AAM. Battery-driven drones already achieve practical ranges of around 100km, while future developments and improving battery technology will enable ranges exceeding 150 km by 2030.
Different aircraft types serve specific purposes in organ transportation. Air taxis, such as the Lilium Jet and Joby’s S4 aircraft, are suitable for transporting heart and lung transplants, as they offer higher payload capacity and can accommodate the operating team that usually chaperones the organ until successful transplantation. Unmanned drones are ideal for transporting organs like the liver, kidney, and pancreas between hospitals. In cases where the distance between hospitals exceeds drone range capabilities, reducing transport time from the hospital to the airport becomes crucial. By utilizing both aircraft types, the transportation of a significant percentage of organs in Germany and Austria can be drastically improved. This improvement enhances allograft quality, acceptance, and ultimately improves the quality of life and lifespan of recipients. Additionally, the adoption of AAM frees up capacity for medical and emergency personnel by eliminating the need for their transportation vehicles.
While the model developed in this study provides valuable insights, the exact origins and destinations of organ transportation could not be determined due to the unpredictable nature of organ donors’ deaths. Pseudo-randomized simulations based on regional origin and destination data were used to derive initial range requirements for AAM vehicles. However, the data lacked information on transport means and transport time, which would have quantified the logistical benefits of AAM more accurately. The German data includes living kidney donations, which do not involve transportation. Eurotransplant was unable to exclude or specifically identify living donations in the data, so we couldn’t filter them out ourselves. In contrast, the Austrian data does not include living donations, as they are excluded by OEBIG.
In conclusion, this study provides valuable insights into the potential application of AAM in organ transplantation in Germany and Austria. This novel technology system of organ transport could reduce the burden on the healthcare system and transport capacities. The findings suggest that a significant percentage of organ transports in these countries could be improved with the use of AAM, leading to shorter ishemia times with enhanced allograft quality, acceptance, and ultimately, improved quality of life and lifespan of recipients. However, further research is needed to address the challenges related to UAV technology scalability, airspace integration47,48,49, safety and regulation, and infrastructure. The infrastructure requirements for AAM at hospitals can be easily met, as existing helicopter landing sites are available at most hospitals with emergency departments and organ transplantation activities. With careful planning and coordination, AAM could revolutionize the field of organ transplantation, offering a more efficient and effective solution to the logistical challenges currently faced in the process.
link
