Nina Halín MSc
Tampere University of Technology
Pori, Finland
E: [email protected]
Mika Junnila MD
Satakunta
Central Hospital, Pori, Finland
E: [email protected]
Wireless monitoring devices measure medical data from a patient and store this information directly into the data collector or send it to a PC where analysis software is located. A system for remote monitoring can be designed in numerous ways; it can send medical parameters from the patient to a central storage, perhaps in real time for constant surveillance, or once a day for later analysis. These kinds of systems are usually used for homecare purpose. Another option is for the sensors, located on the patient, to analyse automatically measured data and transmit them to a PC or ECG screen, from where the doctor can make a diagnosis.
The use of wireless local area networks (IEEE 802.11b, 802.11a, 802.11g and Bluetooth(®)) and low- voltage personal networks will increase dramatically within the next three to four years, and hospital environments will be no exception. Although the exploitation of the technique of wireless networks is currently insufficient and incomplete, the first technical solutions have made it possible to plan new services. While regulations exist on the use of wireless devices in hospitals and with the wireless personal applications, there will be more unconscious wireless devices entering and operating in hospitals. It is feared that these devices may cause electromagnetic interference that could alter the operation of medical equipment and negatively impact patient care.(1-4) There is little knowledge about the impact of the short-range wireless devices on medical equipment and in turn about interference caused to these wireless devices by the hospital environment. This may be the main reason why there are not many complete wireless monitoring devices for the operating room (OR).
Different wireless monitoring products exist on the market today, but they are not specially designed for the OR environment. In the future, however, we believe that wireless products will increasingly enter the OR. Almost all current applications were limited to the registration of a single variable (eg, blood pressure or electrocardiogram), and there are also no devices for real-time wireless patient monitoring. The monitoring of multiple physiological functions was quite complicated to achieve, requiring special measurement devices that were unavailable or too expensive. With all this in mind, we decided to test LifeShirt(TM) equipment from VivoMetrics, Inc.(9)
The LifeShirt
LifeShirt is a multifunction ambulatory device that is capable of simultaneously monitoring several physiological signals and patient reports of symptoms and wellbeing.(10) The LifeShirt system is an extensible data acquisition and processing platform consisting of three parts: a garment, a data recorder and PC-based analysis software (Figure 1). The LifeShirt system is able to collect body data through various sensors that are woven into the vest around the patient’s chest and abdomen. A two-axis accelerometer records patient posture and activity level. The LifeShirt vest is easy to wear and weighs 8oz (0.23kg). Data is collected from respiratory bands, which measure pulmonary function (eg, tidal volume and respiratory rate), currently numbering about 24 parameters, as well as electrical activity of the heart (ECG). An onboard data recorder continuously encrypts and stores the patient’s physiologic data on a compact flash memory card. Other functions can easily be plugged into the system, including pulse oxymetry, EEG/EOG measurement, blood pressure, temperature, capnometry and acoustic monitoring.
Finally, Vivologic, a propietary PC-based software, decrypts and processes recorded data and provides viewing and reporting features for researchers and clinicians to view the full-disclosure, high-resolution waveforms or to look at trends over time. Summary reports that present processed data in concise, graphical and numeric formats can be generated.(11)
The LifeShirt system is designed for ambulatory applications and not specifically for the OR environment. It can measure many parameters that are not needed during the procedure; in testing it we focused on the parameters that are important in the pre- and postoperative monitoring, such as ECG, oxygen saturation and main respiratory functions. The LifeShirt was tested both in and outside the hospital; because of how the vest is worn, it was only used for operations of the legs and arms in hospital, while outside the hospital it was used in everyday situations. There were some problems with the quality of ECG and measuring respiratory functions, but mostly LifeShirt worked well enough and gave us the required information.
Benefits
The LifeShirt system showed that this kind of technology could be brought to OR environment patient monitoring when real-time wireless readability succeeds. For example, it would enable high-risk patient monitoring by putting the vest on when the patient is arriving at the hospital and by taking it off when the patient is leaving. The patient would be under constant observation during their stay in hospital, which could improve patient safety without making the patient feel they are being tied to monitors. It would also help nurses because they would have less work with the cables and electrodes. They could just fix them before the patient goes to the OR, and patients could keep them on in the recovery room too. The cables would be removed when the patient returns to the ward.
Intelligent garment technology could also be used in home follow-up. The proportion of daycase surgery is going to increase in the future, which will lead to a disproportion between the patient volume and healthcare resources. Patients who have undergone daycase surgery are discharged the same day and are still recovering from the operation. The intelligent garment would enable safe and early discharge to the ever-growing patient volume in daycase surgery as well as heavier surgery. Of course, the idea of early discharge could be extended to other fields of medicine too. In that case the intelligent garment should be reliable, easy to wear and sensitive to changes in vital functions. The patient and personnel should also be able to call for help when needed. All this would require suitable service systems that do not exist yet; however, there is always research and development, and an answer may not be far away.
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References
- Kugean C, Krishnan SM, Chutatape O, et al. Proceedings of APCCAS Asia-Pacific Conference; 2002 Dec 16–18; Singapore. p. 313-6.
- Várady P, Benyó Z, Benyó B. An open architecture patient monitoring system using standard technologies. IEEE Trans Inf Technol Biomed 2002 Mar;6(1):95-8.
- Bauer P, Sichitiu M, Istepanian R, Premaratne K. Proceedings of IEEE EMBS International Conference on IT Applications in Biomedicine; 2000 Nov 17–21; Arlington, USA.
- Ormerod DF, Ross B, Naluai-Cecchini A. Proceedings of 6th International Symposium on Wearable Computers; 2002 Oct 7–10; Seattle, USA.
- Available from: www.midmarkdiagnostics.com.
- Available from: www.clevemed.com
- Available from: www.wirelessecg.com
- Available from:www.alivetec.com
- Available from:www.vivometrics.com
- Grossman P. The LifeShirt: a multi-function ambulatory system that monitors health, disease, and medical intervention in the real world. In: Lymberis A, DeRossi D. New generation of wearable systems for e-health: towards a revolution of citizens’ health and life style. Amsterdam: IOS Press; 2004.
- Gárdenas AF, Pon RK, Cameron RB. The 2003 International Conference on Mathematics and Engineering Techniques in Medicine and Biological Sciences; 2003 Jun 23–26; Las Vegas, USA. p. 186-91.
