A wireless arrhythmia detection system, preliminary results from pre-clinical trials Rune Fensli a, Einar Gunnarson b, Torstein Gundersen c a Agder University College, Faculty of Engineering and Science, Grimstad, Norway b Ullevaal University Hospital, Department of Anaesthesia, Oslo, Norway c Sørlandet Sykehus HF, Medical department, Arendal, Norway SHI2006, Scandinavian Conference on Health Informatics, 24-25 August 2006, Aalborg, Denmark Rune Fensli, 2006 1
Outline New wireless technology for arrhythmia detection Conceptual idea Research challenges Hypothesis Research questions (1-3) Some results from a preliminary usability study Recommendations for performing a clinical study Rune Fensli, 2006 2
Conceptual idea If it is possible to develop a simple but wireless ECG sensor which is easy to use, and let the patient wear a device containing computer intelligence, it is assumed that this system could detect abnormal cardiac conditions and automatically transmit those detected events for diagnostic purposes. One important aspect will be to eliminate a wired connection between the sensor electrodes and the Hand-Held Device. This will give the patient the freedom to be mobile and still be under continuously monitoring and thereby to better quality of patient care. Thus this concept is primarily intended for detecting rarely occurrences of cardiac arrhythmias and to follow up patients with heart diseases from their home within a tele-home-care framework [1]. Rune Fensli, 2006 3
Wearable wireless monitoring Wireless transfer of encountered ECG-alarm situations Base station for Mobile telephone GPRS/ GSM INTERNET WPR Internet connected server Remote WPR Client at the hospital The patient is wearing the WPR wireless ECG-sensor The Hand-Held device receives ECG-signals and uses automatic arrhythmia detection algorithms The patient can use a web-based system to contact the doctor and read the encountered ECG-findings The Doctor at the Hospital can make diagnostic evaluations of the recorded ECG-signals [1] Fensli R, Gunnarson E, Gundersen T.: A Wearable ECG-recording System for Continuous Arrhythmia Monitoring in a Wireless Tele-Home-Care Situation. In: The 18th IEEE International Symposium on Computer-Based Medical Systems; 2005 June 23-24, 2005; Dublin, Ireland; 2005. p. 407-12. Rune Fensli, 2006 4
Research challenges Interdisciplinary factors with impact to the process of developing new wireless biomedical sensors Medical procedures Technology solutions User adoption It is necessary to investigate the users needs and behaviour in order to obtain solutions that are both easy to use and can be beneficial in a daily situation, to better quality in patient care. Rune Fensli, 2006 5
Hypothesis The hypothesis for a Ph.D. work is: The main hypothesis is that the wireless ECGsystem easily, and almost without any notice from the patients, can be worn for several days of continuous monitoring and will be able to detect infrequent arrhythmias, while the patient can carry out normally day life activities. The 0-hypothesis is that this new system can not detect arrhythmia occurrences within an acceptable precision, and that the system is not useful for the patients to wear compared to existing Holter monitoring equipment. Rune Fensli, 2006 6
Important user adoption challenges A usability study in 2004 showed that patients felt discomfort using existing Holter monitoring equipment [2]: 41.2% of the patients felt a good deal or some unpleasantness wearing the equipment by day, and 52.9% by night. 32.4% claimed about much or some discomfort with the cabled connection between the electrodes and the recording device 44.1% clamed about discomfort in wearing the recording device It is of importance to find good solutions: Easy to use, and easy to wear without any discomfort to the patient Possibilities for carrying out daily activities including athletic exercise Possibilities for performing normal body wash and taking a shower Rune Fensli, 2006 7
Research question 1 How do female persons feel the new wireless sensor is to be worn for long-time use 1? In order to evaluate the design of the wireless sensor with respect to how this sensor is to be worn by the patient, a preliminary test will be made with the use of a dummy sensor on volunteers. Especially it is important to find out if the physical shape of the sensor can be of any problem to female users, as the sensors need to be placed on the patient s chest. 1 During a long period of lab-tests and pre-clinical tests, only male test persons have used the wireless sensor Rune Fensli, 2006 8
Usability study A preliminary usability study was carried out in May-June 2006, with 8 female volunteers: They where all healthy people, and was asked to wear a dummy sensor for a period of 3 days. The dummy was made of sticky foam, with the same shape and size as the real sensor, however with no ECGmeasuring electronics incorporated. The foam is licensed for 72 hours use as ECG-sensor foam, without any skin irritation problems. They were asked to fill out a query form Questioning different situation (with a 5 level Likert scale) Open questions and comments Rune Fensli, 2006 9
Results from preliminary study (1) 8 female test persons / volunteers. Age: 28 to 60 years, mean 48,5 years Time for wearing the sensor: 9 to 77 hours, mean 58,9 hours Likert scale: (Yes, very much rather much either/or - rather little No, very little) Was it annoying to you wearing the sensor? Did the sensor disturb your night's sleep? Was it troublesome doing body wash? Was it of any trouble doing daily activity? Was it unpleasantly doing physical activity/ sports activity? All reported No, very little or Rather little to those questions. Rune Fensli, 2006 10
Results from preliminary study (2) To the open question, some important aspects were commented: The sensor fell off only after some hours because of moisture/sweat. The adhesive was a little too strong; it was unpleasant when removing the sensor. It was easy to attach the sensor, and the fastening was good. I felt some unpleasantness when wearing a bra. It does not feel any unpleasantness when wearing the sensor; roughly speaking I just forget that I m wearing the sensor. Nearly all of the volunteers reported of skin irritation problems and unpleasantness regarding itchiness and rash/red coloured skin Rune Fensli, 2006 11
Preliminary evaluations Mainly, the shape and size of the sensor was of no problem to the female users, and it was not reported any difficulties in wearing the sensor and carry out daily activity including sports activity. The sensor was easily applied to the chest, and did not give any specific discomfort with respect to using a bra and to wear underneath the clothing. The fact that some volunteers reported that they just forgot wearing the sensor can be an important quality when patients is wearing the sensor for long-time use, in order to detect rarely occurrences of cardiac arrhythmias. However, with respect to skin irritation, the problem addressed needs to be investigated more deeply. Preferably foam can be used with better qualities regarding adhesives, and a semi permeable capability in order to avoid moisture/sweat. Rune Fensli, 2006 12
Research question 2 To which extent is it possible to record ECGsignals to be valid for arrhythmia diagnosis, and without disturbing artefacts due to physical activity, from a 2-electrode sensor? An preliminary objectivistic study is planned: This can be an experimental research study with no consequences for patient care or diagnostic possibilities A small focus group will be selected The sensor system will be used for minimum 3 days This pre-clinical trial will be useful for verification of the sensor technology and obtained signal quality Rune Fensli, 2006 13
Preliminary recordings Preliminary recordings shows acceptable quality in the recorded ECG signal ECG-recordings obtained from the wireless sensor while driving a bike on the road at high speed and good exercise (recorded 21.04-2006 by WPR) Rune Fensli, 2006 14
Research question 3 How reliable is the new ECG-detection system, and will the wireless solution be able to detect occurrences of arrhythmias conditions? Based on an objectivistic measurement study, it is planned a clinical trial. The research protocol is accepted by the Ethical committee Simultaneous ECG-recordings will be obtained from the new wireless sensor system in addition to conventional system A correlation of actual arrhythmia events is thus possible Rune Fensli, 2006 15
Some recommendations A pre-clinical trial should be carried out: Focusing on the usefulness of the sensor as well as the obtained signal quality A clinical trial should include: An objectivistic measurement study A correlational study of arrhythmia occurrences A usability study focusing on field functions and field user effects A survey combined with specific interviews of the patients A survey and/or interviews with doctors and nurses Rune Fensli, 2006 16
Acknowledgments The study is supported from Norwegian Research Council as a MEDKAP-project, and is done in close cooperation with WPR Medical AS, Norway. We would like to thank Medical Department at Sørlandets Sykehus HF, Arendal, for their valuable help in carrying out the trials. Rune Fensli, 2006 17
Publications 1. Fensli R, Gunnarson E, Gundersen T. A Wearable ECG-recording System for Continuous Arrhythmia Monitoring in a Wireless Tele-Home-Care Situation. In: The 18th IEEE International Symposium on Computer-Based Medical Systems; 2005 June 23-24, 2005; Dublin, Ireland; 2005. p. 407-12. 2. Fensli R, Gundersen T, Gunnarson E. Design Requirements for Long-Time ECG recordings in a Tele-Home-Care Situation, A Survey Study. Scandinavian Conference in Health Informatics 2004 ; August 23-25, 2003; Arendal, Norway. pp. 14-18. 3. Fensli R, Gunnarson E, Hejlesen O. A Wireless ECG System for Continuous Event Recording and Communication to a Clinical Alarm Station. 26th Annual International Conference IEEE Engineering in Medicine and Biology Society; September 1-5, 2004; San Francisco; USA; pp 2208-11. 4. Fensli R, Hansen FØ, Gunnarson E, Gundersen T. Wearable Biomedical Sensors in a Tele-Home-Care Context, a Foresight Scenario. Tromsø Telemedicine and ehealth Conference - TTeC06; 12.-14. June 2006; Tromsø, Norway; pp 34. e-mail: rune.fensli@hia.no Rune Fensli, 2006 18