Video Consultation During the COVID-19 Pandemic: A Single Center’s Experience with Lung Transplant Recipients
Introduction
The emergence of the coronavirus disease 2019 (COVID-19) pandemic has disrupted health care systems worldwide.1 Owing to challenges posed by the virus itself as well as redistribution of health care resources during the pandemic, established procedures in outpatient care for those with chronic conditions have been interrupted.2–4
The American Medical Association (AMA) has published recommendations for patient care during the COVID-19 pandemic, including guidelines for remote consultation.5 In the United States, telemedicine has been successfully employed in a wide range of specialties.6,7 Patients with chronic respiratory conditions such as chronic obstructive pulmonary disease8 or interstitial lung diseases9 are especially endangered by COVID-19,10,11 and traveling to specialized health care facilities puts them at additional risk.12 Lung transplant (LTx) recipients are extremely vulnerable due to their intense immunosuppressive therapy.13 LTx patients require complex continuous medical surveillance due to polypharmacy, comorbidities, and the risk of allograft rejection.14–16 Thus, follow-up care by a physician with expertise in LTx cannot be deferred until after the pandemic, nor can it be completely replaced by home visits from general practitioners. This conundrum highlights the need for new strategies.
Video consultations (VCs) have generated increased interest after the rise of video conference programs such as Skype™ and Zoom™ in other sectors of the economy for professional and personal use.17 However, use of conventional video conferencing tools is limited by data protection regulations and concerns for patient privacy.18 Recently, specialized video conference software that protect doctor–patient confidentiality have become more widely available, making VC an attractive option.19 The aim of this study is to analyze the clinical impact, technical feasibility, and patient satisfaction of a rapidly implemented online VC system as a partial replacement for on-site visit (OSV) for LTx patients during the pandemic.
Materials and Methods
A retrospective analysis was performed in a high-volume LTx program during the COVID-19 pandemic in Germany. VC was conducted from calendar week 12 (beginning on March 16, 2020) to calendar week 17 of 2020. Clinical decisions made based upon VC, technical feasibility, and patient satisfaction were investigated.
The reason underpinning each VC was categorized as either “routine surveillance” (replacing a scheduled surveillance visit in a stable patient), “follow-up” (assessment of recently initiated/altered therapies or discussion of recent test results), or “clinical indication” (new symptom requiring assessment). Similar categorization was performed for OSV. Before the COVID-19 pandemic, patients were seen for on-site surveillance consultations at regular intervals of 3–12 months, depending on the time elapsed since transplantation. Similar intervals were chosen during the pandemic for surveillance VC. The decision between VC and OSV was made based on clinical judgement, including whether bronchoscopy was indicated. VC was preferred wherever possible. Criteria such as age or distance between patient’s residence and study site were not considered when choosing between VC and OSV.
All LTx patients in our program who were either scheduled for routine surveillance or required a consultation due to emergent clinical developments during the period between week 12 and 17 of 2020 were eligible for this study.
VC was conducted using a VC tool (Sprechstunde.online™, Deutsche Arzt AG, Essen, Germany) developed for use in an outpatient setting and certified according to the European General Data Protection Regulation (GDPR). Technical requirements were a computer or smart device with a camera, microphone, and speakers, as well as an internet connection. In addition to from the video conference function itself, we also used the text chat platform and a built-in GDPR-approved data file exchange tool. Patients were contacted by phone to schedule an appointment for VC in advance. For first-time VC, the necessary equipment and technical steps were explained during this initial telephone conversation and a downloadable information sheet was provided (Supplementary Data S1). All patients received coaching by our staff through telephone in advance of their appointments in addition to the written step-by-step guide. Technical guidance was estimated by our staff to take 10–15 min per patient for the initial VC, with reduced guidance necessary during subsequent VC. Where establishing VC proved difficult, our nonmedical staff reattempted VC by offering technical guidance to patients through telephone. In cases where our staff suspected that the problem was due to a lack of technical know-how, VC was reattempted when a more technologically versed member of the household was available.
Patients in our program are routinely equipped with a pulse oximeter and home spirometer (AM1/2™; eResearch Technology, Philadelphia) for measurement of Forced Expiratory Volume in 1 Second (FEV1) and Forced Vital Capacity (FVC)20 and are advised to record these values daily, as well as their blood pressure, weight, body temperature, and any current symptoms (Supplementary Data S2). These tools were already part of our follow-up care prepandemic and patients are trained in the use of home spirometers by our medical technicians as part of their first post-transplantation clinic visit. We routinely repeat these training sessions in follow-up visits if the spirometry results are implausible or show significant fluctuation. In addition, home spirometers are checked technically during OSV and our technicians are available for troubleshooting through telephone.
Patients were contacted again on the day of the VC by our administrative staff to arrange an exact time for the consultation. They were then sent an invitation with a link to the VC online software by e-mail or text message. In addition, a standardized online symptom questionnaire was sent to patients (SoSciSurvey GmbH, Munich, Germany) to be filled out before the VC. VC was scheduled in 30-min intervals with 10 min for staff to prepare between appointments. During the first part of each VC, the patient was asked about clinical condition, quality of life, changes in medication, and symptoms of infection. In addition, daily vital sign documentation was examined (Table 1). Respiratory rate was measured using visual observation of the patient at rest by adjusting the camera to view the lower thorax. Breathing actions were counted through a tap counter app for 1 min (Tap Counter with sets™, Philip Braham). In addition, pulse rate and blood oxygen saturation (SpO2) were measured when available and home spirometry results were recorded. The second phase of the consultation focused on the patient’s current complaints, recent medical history, and medication plan. Patients were invited to ask questions and a follow-up appointment (VC or OSV) was arranged. Examples of images taken during VC are shown in Figure 1.
Fig. 1. Sample photos taken during video consultation. Upper left corner: patient taking her body temperature. Upper right corner: patient showing her home spirometry result. Lower left corner: patient showing his pulse oximetry results. Lower right corner: staff member measuring patient’s respiratory rate with tap counter on a tablet.
| PATIENT QUESTIONNAIRE | VITAL SIGNS |
|---|---|
| Quality of life (visual analog scale 0–10) | FEV1 home spirometry |
| General state of health: improved/stable/worsened | Respiratory rate |
| Coughing/sputum, yes/no, onset | Pulse, regular/irregular |
| Myalgia, malaise, yes/no, onset | Blood pressure |
| Runny or stuffy nose, yes/no, onset | Oxygen saturation |
| Sore throat, hoarseness, yes/no, onset | Body temperature |
| Fatigue, yes/no, onset | Body weight |
| Change in medication, yes/no, detail | |
| Physical fitness (flights of stairs without rest) | |
| Local laboratory report if available | |
| Current dose of calcineurin inhibitor |
After the VC, electronic documentation was completed in a clinical and scientific database (FileMaker Pro™; Claris International, Inc., Santa Clara, CA). After the interview, patients were sent an anonymous questionnaire through e-mail to ascertain their satisfaction with VC. Questionnaire data were exported from SoSciSurvey into SPSS Statistics data format. Statistical analysis was performed using IBM SPSS v26™ (IBM SPSS Statistics, Armonk, NY). Categorical variables are presented as numbers (n) or percentages (%), and continuous variables as median and interquartile ranges, unless indicated otherwise. Statistical significance between the groups was assessed using χ2 or Mann–Whitney U test as appropriate. A p-value of <0.05 was considered statistically significant. All tests were two sided. For demographic data, patients were sorted into groups depending on the type of first visit during the study period.
This study was performed in accordance with the ethical guidelines of the 1975 Declaration of Helsinki. All patients provided informed consent before transplantation allowing the use of their data for scientific purposes, as approved by the Ethics Committee of Hannover Medical School (Ethics Committee Vote Nr. 2923–2015). According to our Ethics Committee, additional approval was not necessary, as data acquisition was retrospective and observational, data were anonymized and the study relied on information collected as part of routine care. Patients seen in Figure 1 gave written consent for the publication of their images.
Results
During the 6-week study period, 75 VCs were performed for 53 patients, compared with 75 OSVs with 51 patients. The total number of consultations decreased by 47% during the COVID-19 crisis in 2020 compared with the equivalent time frame in 2019. The ratio of VC to OSV increased over the course of the pandemic (Fig. 2). Fourteen patients had consultations by both VC and OSV during the study period. Patient characteristics are listed in Table 2. Both the median time post-transplantation and the median time between consultations were significantly shorter for on-site patients. The majority of OSVs were required due to short- to medium-term post-transplant complications necessitating bronchoscopy. Average distance from patients’ home to our center was similar in both groups (Fig. 3).
Fig. 2. Number of physician–patient consultations per week during study period. Breakdown of video consultations and on-site visits by calendar week. Study period begins March 16th, 2020, corresponding to calendar week 12.
Fig. 3. Map depicting geographic distribution of patients’ location. Oval marker denotes study site (Hannover Medical School). Gray lines mark state borders.
| VC (n = 53) | OSVs (n = 51) | p | |
|---|---|---|---|
| Gender, female, n (%) | 26 (49) | 24 (47) | 0.838 |
| Age at visit, years | 0.844 | ||
| Median (25, 75 quartile) | 54 (43, 60) | 55 (50, 61) | |
| Age at Tx, years | 0.117 | ||
| Median (25, 75 quartile) | 49 (34, 57) | 53 (46, 59) | |
| Months after LTx | <0.001 | ||
| Median (25, 75 quartile) | 51 (15, 99) | 11 (5, 38) | |
| Tx procedure, n (%) | 0.168 | ||
| Bilateral | 47 (90) | 50 (98) | |
| Unilateral | 1 (2) | 1 (2) | |
| Combined | 4 (8) | ||
| Tx diagnosis, n (%) | 0.015 | ||
| Cystic fibrosis | 14 (26) | 3 (6) | |
| Fibrosis | 15 (28) | 14 (27) | |
| Emphysema | 13 (25) | 24 (47) | |
| Other | 11 (21) | 10 (20) | |
| CLAD, n (%) | 17 (32) | 14 (27%) | 0.606 |
| Days since last OSV | <0.001 | ||
| Median (25, 75 quartile) | 84 (48, 177) | 34 (20, 40) | |
| Distance to site, kilometers | 0.556 | ||
| Median (25, 75 quartile) | 197 (112, 262) | 158 (85, 244) | |
| Contacts during study period, n | 0.148 | ||
| Median (25, 75 quartile) | 1 (1, 1) | 1 (1, 2) |
VCs were distributed evenly between routine surveillance (24/75, 32%), follow-up (27/75, 36%), and clinical indication (24/75, 32%) (Table 3). Among OSV, 14/75 (19%) were for routine surveillance, 6/75 (8%) for follow-up, and 55/75 (81%) due to clinical indication. Most surveillance OSV (69%) took place during the first week of the study period. As time went on and our telemedicine program became more established, a decrease in routine surveillance visits conducted on-site was observed. For comparison, between calendar weeks 12 and 17 of 2019, 280 LTx recipients were seen on-site. Consultations scheduled due to clinical indication accounted for 19% of visits. The remaining 81% of visits were routine surveillance consultations. Of these 280 patients, 37% underwent bronchoscopy. Management of airway complications accounted for 33% of all bronchoscopies performed. VCs due to clinical indication in 2020 were more frequent than indication-driven OSVs during the historical control period in 2019.
| COMPLETED VCs (n = 75) | |
|---|---|
| Patient device, n (%) | |
| Laptop/computer | 59 (79) |
| Tablet | 3 (4) |
| Smartphone | 13 (17) |
| Duration of contact, minutes | |
| Median (25, 75 quartile) | 27 (19, 34) |
| Reason for consultation, n (%) | |
| Routine surveillance | 24 (32) |
| Follow-up | 27 (36) |
| Clinical indication | 24 (32) |
| Availability of diagnostic parameters, n (%) | |
| Pulse oximetry | 60 (80) |
| Respiratory rate | 67 (89) |
| FEV1 | 66 (88) |
| Body temperature | 57 (76) |
| Pulse | 59 (79) |
| Patient diary | 33 (44) |
| Outcome of consultation, n (%) | |
| Medication changed | 27 (36) |
| Hospitalization | 2 (3) |
| OSV | 3 (4) |
| Visit local practitioner | 14 (19) |
| No specific measures | 28 (38) |
| Reported technical problems during consultation, n (%) | |
| e.g., poor sound and frozen picture | 11 (15) |
A minority of VC (38%) did not lead to specific action such as medication change. In 62% of cases, VC led to a concrete clinical recommendation. Fourteen consultations (19%) led to the recommendation for further diagnostic steps by the primary care physician such as laboratory testing or imaging studies. Twenty-seven consultations (36%) led to a change in medication. Three patients (4%) were brought in for an OSV, due to findings on VC. In each of these three cases, acute allograft rejection was subsequently diagnosed. Two patients (3%) were admitted for inpatient care due to symptoms identified during VC (Table 2). Two VCs occurred while patients were in home quarantine due to COVID-19. In one case, a 47-year-old man had previously presented to his general practitioner for cough and mild dyspnea and tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We, therefore, arranged a VC during home quarantine. On VC, we observed respiratory distress and a low SpO2 of 81% on room air. Proper function of the pulse oximeter was checked during the VC by measuring the SpO2 of the patient’s father, who showed normal values. We arranged the immediate admission of this patient to his local hospital. His clinical condition worsened drastically within the next 48 h, culminating in ICU admission, invasive ventilation and ECMO cannulation. In another case of VC leading to hospitalization, a 56-year-old woman showed signs concerning for pleural empyema during a VC after a similar episode 3 weeks earlier that had been treated surgically. Owing to findings on VC, this patient was admitted to our hospital for surgical revision the next day.
Minor technical issues on the patient’s end such as poor sound quality or intermittent screen freezing were reported during 15% of VC (Table 3). Initially, we also encountered in-hospital technical difficulties caused by the VC tool triggering our institution’s firewall, which required intervention by our IT staff. The high data volume required for VC also challenged our institution’s internet connection, especially during peak use times. Scheduling VC in the afternoon partially alleviated this problem.
In eight patients, VC failed due to either patients’ lack of necessary equipment or due to technical difficulties in establishing a connection (either no audio, no video, or no connection at all). However, no VC failed due to lost connection once VC had been successfully established. Three patients refused VC for personal reasons (Table 4). Altogether, VC was successfully established in 75/86 (87%) cases. The median age of patients where VC was not established was 62, 8 years older than the median age of patients with whom VC was successfully implemented.
| ATTEMPTED VCs (n = 86) | |
|---|---|
| Completed VCs, n (%) | 75 (87) |
| Failed VCs, n (%) | 11 (13) |
| Reason for failure, n (%) | |
| Technical problems | 6 (55) |
| Missing devices | 2 (18) |
| Patient refused VC | 3 (27) |
Of the 53 patients who received VC, 37 (70%) responded to a questionnaire on their satisfaction with the experience. The vast majority reported a high degree of satisfaction. The clinical aspects of the consultation were rated more favorably than the technical ones (Fig. 4).
Fig. 4. Patient-reported satisfaction with video consultation (n = 38). Boxplots show patient satisfaction as measured on a visual analog scale.
Discussion
To our knowledge, this is the largest study on the implementation of VC in chronic respiratory diseases during the COVID-19 pandemic. VC increased in our center for follow-up care post LTx during the study period, whereas OSV declined. One third of VC occurred due to clinical indication. Overall satisfaction with VC was high.
There is currently one published study evaluating VC in transplant patients. In a randomized controlled trial, the readmission rate in 100 recent liver transplant recipients was lower in patients receiving telemedicine in addition to standard of care (SOC) compared with patients receiving SOC only.21
Outside the field of transplant medicine, VC has been studied in a variety of clinical contexts. In the home management of 35 newborns with severe heart defects, VC proved superior to both SOC and telephone consultation in reducing the rate of readmission. This study reported technical difficulties in 17% of VC, which is similar to the 15% rate we observed.22 A majority of studies comparing VC with OSV have been conducted in the field of mental health.23 Although conclusions from these studies are limited by small sample size, the reported patient satisfaction rates are high.24
An American group reported on the implementation of VC in the care of 38 cystic fibrosis patients during a 4-week interval during the COVID-19 pandemic.7 This study employed a commercial video chat program that does not conform to European Union GDPR requirements. In this study, VC was performed exclusively in patients without symptoms of infection, leading to two changes in medication and one OSV as a consequence of VC. Patient satisfaction was not assessed. Rabuñal et al. recently reported on the use of telemedicine for monitoring of symptoms and vital signs in SARS-CoV-2 positive patients in home isolation. Notably, the monitoring team was able to identify clinical deterioration and initiate timely hospital admission in 14 out of 275 monitored patients. Although this study relied on vital sign monitoring without use of VC, it underlines the utility of telemedicine in the response to the COVID-19 pandemic.25
During the current pandemic, a rapid transition to telemedicine was necessary to guarantee the continued care of our LTx patients while limiting their potential exposure to SARS-CoV-2. The observed drop in patient appointments, virtual or in person, during the pandemic reflects a lag in implementing telemedicine rapidly and with little preparation. Until the beginning of the study period described in this study, none of our patients were seen through VC and no infrastructure for this transition was in place. The precipitous reduction in OSV seen in week 11 and 12 and the subsequent steady rise in VC speaks to the workability of a swift transition (Fig. 2). However, specific patient populations continue to require care that cannot be delivered by VC. For example, graft hypoperfusion in the early-stage post-LTx can lead to the development of airway complications such as fibrinous bronchitis and bronchial stenosis, requiring repeated interventional bronchoscopy.26 Likewise, the diagnosis of acute allograft rejection often requires bronchoscopic lung tissue biopsy.15 Among clinically indicated OSV during the study period, the vast majority were for such endoscopic procedures.
The success of VC was facilitated by a system of patient-owned monitoring devices (home spirometry and pulse oximetry) to objectively assess patients’ vital signs. Thus, we were able to identify hypoxemia in a COVID-19 patient and initiate hospital admission before severe clinical deterioration occurred. The implementation of a standardized symptom questionnaire helped lay the groundwork for VC. The measurement of respiratory rate by VC proved a valuable tool in the clinical assessment of patients. This highlights the advantages of VC in fields that rely heavily on the visual assessment of patients, such as respiratory medicine and infectious disease.
The majority of VC resulted in either a change of medication or a recommendation for further diagnostic testing, which required our center’s expertise due to the complexity of this patient population. We believe this approach can be translated to a wide range of chronic diseases requiring specialized medical care. However, a close collaboration with physicians local to the patient’s place of residence remains paramount, especially when further diagnostic steps or procedures are required. In the context of the pandemic making travel difficult, as well as the risk of nosocomial SARS-CoV-2 infection during a visit to a health care facility, VC represents a balance between access to specialist expertise and exposure prevention.
The vast majority of patients were satisfied by both the clinical the technical aspects of VC. This high rate of satisfaction is likely due to the structured approach we employed to ensure a smooth logistical and technical process. However, the lack of response to patient satisfaction questionnaires in 30% of VC patients may have caused us to overestimate patient satisfaction with VC. One out of eight attempted VC was unsuccessful due to patients’ lack of equipment, technical difficulties, or patient refusal. Patients with whom VC was not established tended to be older, underlining the concern that patient age poses a relevant barrier to telemedicine.27
It is important to note that Germany has poor digital infrastructure compared with other western European countries, particularly in the health care sector.28 However, our overall success in implementing VC highlights the willingness of our patients to transition to a telemedicine approach. Direct data transmission from patient-owned monitoring devices, as is already common in a number of commercial health and fitness devices, could facilitate follow-up care in the future.29 There are a variety of additional tools in development to allow more diagnostic steps to be taken remotely. For example, a Belgian group is currently developing a system of remote pulmonary auscultation.30 In time, some combination of OSV and VC will likely become standard in a wide range of medical specialties. The current COVID-19 crisis and the attendant shift to telemedicine may well catalyze a new level of acceptance of this technology by patients and physicians.
Conclusions
In conclusion, we demonstrate that VC can be a valuable tool in the effort to provide quality health care to LTx patients during the COVID-19 pandemic. Our center’s experience and the roadmap outlined earlier provide a framework for the implementation of telemedicine for patients with chronic respiratory diseases and other chronic conditions. The risk of morbidity and mortality from COVID-19 will likely inform decision making in health care systems worldwide for the foreseeable future. In this context, VC will play an important role for physicians treating chronically ill patients, and research investigating best practices and new models of care in this area are more relevant than ever.
Acknowledgments
We thank our administrative coordinators Konstantina Zang-Pappa, Linda Häsler, Anita Fuhrmann, and Bianca Metzdorf for their patience with both patients and physicians. Their persistence and efficiency made our clinic’s transition to telemedicine possible.
Disclosure Statement
No competing financial interests exist.
Funding Information
No funding was received for this article.
Supplementary Material
References
- 1. . WHO declares COVID-19 a pandemic. Acta Biomed 2020;91:157–160. Google Scholar
- 2. . A war on two fronts: Cancer care in the time of COVID-19. Ann Intern Med 2020;172:756–758. Crossref, Google Scholar
- 3. . COVID-19 pandemic will have a long-lasting impact on the quality of cirrhosis care. J Hepatol 2020;73:441–445. Crossref, Medline, Google Scholar
- 4. . Translating COVID-19 pandemic surge theory to practice in the emergency department: How to expand structure. Disaster Med Public Health Prep 2020;27:1–10. Crossref, Google Scholar
- 5.
AMA quick guide to telemedicine in practice . American Medical Association Web site. Available at https://www.ama-assn.org/practice-management/digital/ama-quick-guide-telemedicine-practice (last accessedMay 10, 2020 ). Google Scholar - 6. . Keep calm and log on: Telemedicine for COVID-19 pandemic response. J Hosp Med 2020;15:302–304. Crossref, Medline, Google Scholar
- 7. A feasibility study of urgent implementation of cystic fibrosis multidisciplinary telemedicine clinic in the face of COVID-19 pandemic: Single-center experience. Telemed J E Health 2020;26:978–984. Link, Google Scholar
- 8. The impact of COPD and smoking history on the severity of covid-19: A systemic review and meta-analysis. J Med Virol 2020;92:1915–1921. Crossref, Google Scholar
- 9. When the game changes: Guidance to adjust sarcoidosis management during the COVID-19 pandemic. Chest 2020;158:892–895. Crossref, Google Scholar
- 10. . Chronic kidney disease is associated with severe coronavirus disease 2019 (COVID-19) infection. Int Urol Nephrol 2020;52:1193–1194. Crossref, Google Scholar
- 11. . Covid-19 and long-term conditions: What if you have cancer, diabetes, or chronic kidney disease? BMJ 2020;368:m1174. Crossref, Google Scholar
- 12. . Social distancing during the COVID-19 pandemic: Staying home save lives. Am J Emerg Med 2020;38:1519–1520. Crossref, Google Scholar
- 13. COVID-19 in solid organ transplant recipients: Initial report from the US epicenter. Am J Transplant 2020;29:1800–1808. Crossref, Google Scholar
- 14. . Comprehensive care of the lung transplant patient. Chest 2017;152:150–164. Crossref, Google Scholar
- 15. . Acute rejection and antibody-mediated rejection in lung transplantation. Clin Chest Med 2017;38:667–675. Crossref, Google Scholar
- 16. . Infections after lung transplantation. J Thorac Dis 2018;10:3849–3868. Crossref, Google Scholar
- 17. . The clinical use of Skype—For which patients, with which problems and in which settings? A snapshot review of the literature. Int J Med Inform 2015;84:737–742. Crossref, Medline, Google Scholar
- 18. . Application of ethics for providing telemedicine services and information technology. Med Arch 2017;71:351–355. Crossref, Medline, Google Scholar
- 19. . Video consultations for covid-19. BMJ 2020;368:m998. Crossref, Medline, Google Scholar
- 20. Effect of adherence to home spirometry on bronchiolitis obliterans and graft survival after lung transplantation. Transplantation 2009;88:129–134. Crossref, Google Scholar
- 21. . Telemedicine based remote home monitoring after liver transplantation: Results of a randomized prospective trial. Ann Surg 2019;270:564–572. Crossref, Google Scholar
- 22. A randomised trial of a remote home support program for infants with major congenital heart disease. Heart 2012;98:1523–1528. Crossref, Medline, Google Scholar
- 23. The medium, the message and the measure: A theory-driven review on the value of telehealth as a patient-facing digital health innovation. Health Econ Rev 2019;9:21. Crossref, Google Scholar
- 24. Videoconferencing psychotherapy: A systematic review. Psychol Serv 2012;9:111–131. Crossref, Medline, Google Scholar
- 25. Usefulness of a telemedicine tool TELEA in the management of the COVID-19 pandemic. Telemed J E Health 2020. [Epub ahead of print]; DOI: 10.1089/tmj.2020.0144. Google Scholar
- 26. ISHLT consensus statement on adult and pediatric airway complications after lung transplantation: Definitions, grading system, and therapeutics. J Heart Lung Transplant 2018;37:548–563. Crossref, Google Scholar
- 27. . Evaluating barriers to adopting telemedicine worldwide: A systematic review. J Telemed Telecare 2016;24:4–12. Crossref, Medline, Google Scholar
- 28. . Barriers to digitalisation of healthcare in Germany: A survey of experts. Gesundheitswesen 2018;80:939–945. Google Scholar
- 29. . Utility of consumer physical activity trackers as an intervention tool in cardiovascular disease prevention and treatment. Prog Cardiovasc Dis 2016;58:613–619. Crossref, Medline, Google Scholar
- 30. , CoSys-Lab. Project CORELSA—The open-source remote lung sound monitor system. Available at https://www.uantwerpen.be/en/about-uantwerp/faculties/faculty-of-applied-engineering/news-and-activities/news/project-corelsa/;Website. https://www.youtube.com/watch?v=8lrVm3xHisY&feature=emb_title. Updated 2020 (last accessed
May 1, 2020 ). Google Scholar