A New Imaging and Data Transmitting Devicefor Telemonitoring of Diabetic Foot Syndrome Patients

Piotr Foltynski, Ph.D., Piotr Ladyzynski, Ph.D., D.Sc., Karolina Migalska-Musial, B.Sc.,Stanislawa Sabalinska, Anna Ciechanowska, Ph.D., and Jan Wojcicki, Prof.

Abstract

Background: Proper healing of ulcers and wounds on the feet of diabetes patients is important in order toprevent amputation. If the wound area reduction during the first 4 weeks of the treatment is not 40% or more,reevaluation of the treatment is necessary. The wound area evaluation is not complicated when the patient staysat a hospital, but when he or she goes home the physician does not have a tool allowing monitoring of thewound area.Methods and Results: The aim of the present article is to present a new device able to take a wound picture andsend it automatically to the database. This device, called the Patient’s Module (PM), is also able to downloaddata from the memories of blood pressure and blood glucose meters and send the data to the database. The PMis able to operate within the TeleDiaFoS system (developed earlier in collaboration with the Department andClinic of Gastroenterology and Metabolic Diseases, Medical University of Warsaw, Warsaw, Poland) aimed atmonitoring of treatment of patients with diabetic foot syndrome. The PM was tested on 10 type 2 diabetespatients during a 3-month period.Conclusions: The study revealed that the PM can be used as a home telemonitoring device, and the analysis ofthe data sent from patient’s home enables the assessment of wound healing progress, giving the physician thepossibility for earlier change of the treatment if the wound area reduction is not satisfactory.

Introduction

One of the late complications of diabetes is diabeticfoot syndrome (DFS), characterized by reduction in

blood supply to the feet that leads to neuropathy and angio-pathy. DFS patients are at risk of developing foot ulcers andwounds as a result of neuropathy. Those injuries are slow toheal because of angiopathy, and as a result they can cause footamputation. DFS patients receive the standard wound care,by default. When the progress of wound healing is not satis-fying, the treatment should be adjusted. The Wound HealingSociety gives some guidelines for DFS treatment.1 One ofthem (guideline number 4.5) is related to progress of thewound area change after 4 weeks of treatment: when thewound area reduction is less than 40%, the therapy should bereevaluated. Sheehan et al.2 stated that change in wound areaafter 4 weeks is a predictor of wound healing in 12 weeks.Lavery et al.3 claimed that wound area reduction of 10% after1 week is also a valuable predictor of wound closure after 16weeks. Cardinal et al.4 found that wounds with poor healingprogress at 4 weeks were more likely to remain unhealed after8 additional weeks of treatment. Coerper et al.5 showed that

area reduction after 4 weeks of treatment is a useful tool toestimate the probability of wound healing; they also con-cluded that reevaluation of the treatment schedule is neces-sary for wounds that do not reach 50% area reduction within4 weeks after beginning of the treatment.

When a DFS patient receives standard outpatient cliniccare, the time between visits is longer than 4 weeks. Thewound state is not monitored during this time. In order tomonitor progress of healing when the patient stays at home, adevice allowing taking a wound picture and sending it to-gether with other information related to the patient state to thephysician is needed. Based on that information the physicianwould be able to determine the progress of wound healingand, in the case of insufficient progress, to prepare for changeof the wound therapy.

One can conclude that a reliable tool for wound area mea-surement is necessary and that this tool should be common inclinical practice. It is a simple way to evaluate the wound areawhen the maximal length of wound is known and the width isperpendicular to the length. The area of an ellipse of chordsequal to the length and the width of the wound is a goodestimator of the wound area when the wound is not large. The

Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.

DIABETES TECHNOLOGY & THERAPEUTICSVolume 13, Number 8, 2011ª Mary Ann Liebert, Inc.DOI: 10.1089/dia.2011.0004

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estimation of wound area should not be used when the ther-apeutic decisions depend on the wound area change. In such acase, to determine the wound area a more reliable methodcalled planimetrics should be used. There are some devicesand systems based on this method. A Visitrak from Smith &Nephew (London, UK)6 needs a transparent foil on whichwound boundaries are traced when, in the first step, the foil isplaced onto the wound and, in the second step, the tracedwound is redrawn onto the digitizing tablet, which calculatesautomatically the wound area. In other systems the woundarea is calculated from digital pictures of the wound. Examplesof such systems are PictZar� (BioVisual Technologies, LLC,Westwood, NJ)7 and VERG.8 Some of the systems are portable,such as the Silhouette9 from Aranz Medical Ltd. (Christchurch,New Zealand) or the Wound Measurement Device from theGeorgia Institute of Technology (Atlanta, GA).10 More ad-vanced systems are able to produce a three-dimensional imageof the wound and can measure the wound volume. Examplesof such a systems are MAVIS11 and DigiSkin.12

None of the above-mentioned systems of wound areameasurement can be used by the patient at home as they canbe used only by trained operators and are not designed to beoperated by the patient.

The main objective of this article is to present a new devicedesigned and developed at the Institute of Biocybernetics andBiomedical Engineering, Polish Academy of Sciences (War-saw, Poland) for telemonitoring of patients with DFS treatedat home. The device is operated by the patient without theassistance of other trained person.

Materials and Methods

The imaging device developed, which is also able todownload blood glucose and blood pressure data and sendthe data to the Central Clinical Server (CCS), is called thePatient’s Module (PM). The PM is able to work within theTeleDiaFoS system (developed earlier in collaboration withthe Department and Clinic of Gastroenterology and MetabolicDiseases, Medical University of Warsaw, Warsaw) designedfor monitoring DFS patients.

PM of the TeleDiaFoS system

The PM was designed with some major assumptions:

� the patient’s safety in the sphere of elimination of pos-sibility of the wound infection

� good quality of the wound picture (with minimal filesize and minimal time of scanning)

� data transmission (blood glucose and blood pressure)� easy to use

Before the development of the PM, a digital camera, a multi-media GSM phone, and an optical scanner were preselected asimaging devices. The digital camera and telephone were ex-cluded because of the need to develop a customized foot sup-port, a stand for the device, and a light source with a support.The optical scanner requires a PC to work, but it assures goodlighting, and there is no problem with the foot support becausethe foot lies on the scanner glass window. An optical scannerwas selected in order to develop an imaging device.

The patient’s safety is assured by developing a two-stageprocedure of the PM disinfection. Microzid AF Liquid�

(Schulke & Mayr, Norderstedt, Germany) and Softasept�N

(B. Braun, Melsungen, Germany) are used in the first and thesecond steps of disinfection, respectively. The efficacy of thisprocedure was evaluated by microbiological tests in whichthe PM surface was covered by a solution containing woundbacteria, and then, after the disinfection procedure, samples totest microbiological growth were taken. The test gave nega-tive results in eight samples, what was enough to assume theprocedure was a safe one. The upper side of the PM is made oftempered glass in order to reduce the risk of injuries whenaccidentally broken.

The PM case is made of a composite solid surface materialthat is non-porous and resistant to bacteria. It is also trans-parent to electromagnetic waves, which is important when aGSM modem is operating inside a box made of this material.

The wound image quality was verified in function of theimage resolution, file size, and jpeg compression coefficient.The optimal result was reached when the image resolutionwas 200 dpi and the compression coefficient was equal to 70.The file size was 150–250 kB, which was not too big to send itwith the slowest (GPRS) internet connection used in the PM.The time of foot scanning is about 15 s. The patient is in thesitting position, having one foot onto the floor while the otheris scanned (Fig. 1).

The Accu-Chek� Active and Accu-Chek Go glucometers(Roche, Mannheim, Germany) and 3BU1-4PC blood pressuremeter (Microlife, Widnau, Switzerland) were used in theTeleDiaFoS system. The PM software is able to communicatewith the meters and to download the measurement data andsend the data to the CCS. The procedure of data sending usesan ftp connection to send the data files to the server. There is aprocess running at the server that analyzes the files and savesthe data in the database tables. Physicians can access the pa-tients’ data using local workstations with local databases. Thedata in the local workstations are synchronized with the datain the CCS in order to enable the physicians to look into thenewest patients’ data.

When developing the PM it was assumed that the patientwill get no support in the device management, so the PMshould be easy to use as much as possible. Therefore it wasequipped with a two-button remote control.

The PM consists of an optical scanner, PC motherboardwith processor and RAM memory, hard disk drive, RS232-IRconverter, AD converter with IO ports, wireless GSM modem,wireless controller board for remote control, and custom-made case. There is a scanner window 110 mm wide and297 mm tall in the upper surface of the PM. The dimensions ofthe scanner window assure scanning of one foot at a time.

The PM is an autonomic device in the sphere of connection tothe internet, and therefore there are no requirements regardingthe internet infrastructure at the patient’s home. The PM isconnected to the internet by a wireless modem, which needs avalid telecom SIM card. When there are problems with the in-ternet connection due to the GSM network coverage, anotherGSM network can be used after the SIM card is changed.

When the PM starts, it downloads the configuration pa-rameters (patient’s ID, conversion coefficient, and automaticswitch-off time) from the CCS. If the connection to the CCS isnot available, it uses stored values of those parameters. Whenthe PM is ready to use, the patient selects the desired option ofthe PM operation: (1) scanning, (2) data downloading, or (3)switching the PM off. After scanning and data downloadingthe PM software automatically sends the data to the CCS and

862 FOLTYNSKI ET AL.

switches the PM off. There is a data backup folder at the harddrive of the PM, and every file ready to send to the CCS iscopied to this folder to assure data recovery in case of datatransmission failure.

The procedure of the foot wound picture taking requiresthe few following steps:

1. Putting the PM onto the floor.2. Disinfecting of the PM.3. Switching the PM on.4. Taking off the wound dressing.5. Putting a foot onto the scanner window in order to take

a foot picture (while the patient is sitting).6. Cleaning the PM and storing it in a safe place.

After the wound picture is taken, the PM sends it to the CCS.The physicians can evaluate the foot sole skin and thewound—its appearance and area.

Calculation of wound area in the TeleDiaFoS system

The wound area measurement in the TeleDiaFoS system isbased on counting of pixels within the area or areas traced byoperator. Tracing of a wound may be done precisely when thewound boundaries are well-defined as shown in Figure 2;however, a debridement is necessary in case of dead tissuepresence around the wound (Fig. 3). The area of the tracedwound is a product of the pixel number and the area of asingle pixel. The resolution of the foot pictures is 200 dpi, andtherefore every image pixel represents a square with sides oflength 0.127 mm. The area of a single pixel is 0.016129 mm2.The software calculates also the relative wound area changefrom the beginning of treatment. It is assumed by default thatthe day when the first picture was taken is the beginning oftreatment.

The study protocol

The inclusion criteria of patient selection were as follows:diabetes type 2, diagnosis of foot neuropathy, and ulcerpresent on one foot only. The exclusion criteria were asfollows: diabetes type 1, secondary diabetes, retinopathy,nephropathy, heart disease, and mental retardation. The pa-tients were selected in order to verify the technical feasibility

FIG. 2. Example of a foot wound with well-defined woundboundaries.

FIG. 1. Patient’s Module while taking a picture of the foot sole.

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of the monitoring system, and therefore we decided to choosethose with type 2 diabetes with neuropathy. We wanted tohave a homogeneous group. In patients with type 1 diabeteswe could have younger persons, but we wanted to showthat even older patients have no problem with managingthe PM. We assumed that the patient will be the only per-son for the PM management, so it was necessary to excludethose with retinopathy and as well those with mental retar-dation. All patients had foot wounds due to neuropathy, butall types of foot wounds are supposed to be monitored usingthe PM.

The patients were using the PM at their homes, but prior tothat they were trained in managing the PM in the clinic or attheir homes. They were asked to take a picture of the footwound not more frequently than wound dressing change. Themeasurement data (glycemia and blood pressure) weretransmitted to the CCS a few times a week. Each foot woundpicture was evaluated by four observers in order to calculatewound area and its change from the beginning of healing.Mean value of the foot wound area and coefficient of variation(CV) were calculated for each wound. Median, minimal, andmaximal values of CV were calculated for each wound.

The study was approved by the ethics committee of theWarsaw Medical University.

Results

Two hundred fifty-six wound images were sent by 10 pa-tients to the CCS. Table 1 shows the monitoring period,number of assessed wounds, initial wound area, and itschange after 4 and 12 weeks or at the end of monitoring for allpatients. Median of CVs and their range are also shown inTable 1.

Figure 4 shows the wound area change of the patient withwell-defined wound boundaries shown in Figure 2. This pa-tient achieved wound area reduction by more than 50% in 4weeks of treatment.

Figure 5 shows the wound area change of a patient with notwell-defined wound boundaries. As a result there are largeCVs of the means. This patient achieved wound area reduc-tion of �23.9% in 4 weeks of treatment.

Discussion

The estimated cost of the PM is $2,500 US on the basis of afew units that have been developed for feasibility assessment.If the production of thousands of units is considered, the costmay be lower than $1,000 US per device. Another cost is thedata transmission fee. As we previously have evaluated,13 thecost of data transmission for 3 months is about $17 US.

FIG. 3. (A) Example of a foot wound in which boundaries are poorly defined. (B) The same wound after debridement.

Table 1. Summary of the Patient’s Module Application on 10 Patients

Patient’sID

Monitoringperiod (days)

Numberof assessed

wound picturesInitial wound

area (cm2)

Area changeafter

4 weeks (%)

Area change after12 weeks or in the end

of monitoring (%)

Medianof CV

(range) (%)

1 78 24 0.36 �33.1 �17.9 20.9 (2.2–46.6)2 95 13 1.88 �63.2 �98.2 13.8 (5.9–54.7)3 75 13 5.37 �62.4 �95.4 7.2 (2.1–64.2)4 77 9 1.05 þ10.4 þ7.7 19.4 (7.2–28.8)5 95 53 2.44 �83.9 �83.5 14.5 (4.6–54.0)6 54 16 0.63 �45.6 �8.5 21.9 (4.8–70.3)7 114 49 3.00 �54.7 �48.4 40.8 (8.4–69.8)8 103 21 0.45 �23.9 þ83.8 64.3 (31.7–80.4)9 131 35 33.23 �24.3 �57.3 3.9 (1.8–10.4)10 67 13 4.93 �11.5 þ0.3 6.1 (2.1–12.4)

CV, coefficient of variation.

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However, those costs can be eliminated if at the patient’shome there is an internet connection that can be used for thePM data transmission. The PM is already equipped with anetwork card (for cable connection); as well, it can be pro-vided with a Wi-Fi adapter for wireless connection (cost about$5–10 US). Instead of equipping the patient with a PM, we canemploy a nurse to do the photographic documentation of thepatient’s foot every week. Such a nurse should be paid at least$400 US for each patient for 3 months plus costs of travel.

The PM has certain limitations. The picture recorded by ascanner is a projection of the curved skin surface to a flatscanning surface. The smaller the angle between the plane inwhich the wound is lying and the scanning plane, the larger isthe area reproducibility by the scanner. The DFS woundsappear mostly in the regions of the foot sole, where the foot

has contact with the ground, and those regions of foot areparallel to the ground. The errors of area reproducibility fromthose regions are negligible. Our earlier research revealed thatmore than 98% of foot wounds are located on the foot sole.That part of the foot is in good approximation parallel to thescanning plane, and therefore the area reproducibility is al-most 100%. If the angle is equal, for instance, to 108, scanninggives an underestimation of 1.52% only. In the study14 com-paring wound area values recorded by the Visitrak, Silhou-ette, linear measurement, and the PM, strong correlations(Pearson correlation coefficient R> 0.985) had been foundamong the Visitrak, Silhouette, and the PM. In evaluation ofthe wound healing process, relative area change is more im-portant than its absolute value. When a set of pictures of thewound is taken by the PM over time, the angle between the

FIG. 4. Foot wound area of a patient (ID number 3) over a 75-day period of monitoring. Data are mean� SD values.

FIG. 5. Foot wound area of a patient (ID number 7) over a 114-day period of monitoring. Data are mean� SD values.

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scanning plane and the wound plane is almost constant (frompicture to picture), and as a result the percentage change of thewound area remains, in good approximation, independent ofthis angle.

Larger deviations in wound area measurements come fromuncertainties of positions of the wound edges, which was alsopointed out by Flanagan.15 The same wound is not traced inthe same way by different operators—the positions of woundedges differ from one operator to other. This is an importantsource of error in wound area measurement. The best resultsin the wound area measurement can be achieved after wounddebridement by a trained nurse. When the dead tissue is re-moved from the wound, the edges of the wound are clearlyvisible and can be precisely marked (Fig. 3). Otherwise, largeuncertainties of positions of the wound edges may be an im-portant issue in the wound area determination. In the case ofhyperkeratosis presence around the wound, the patientshould be called to visit the ambulatory unit in order to re-move the dead tissue.

The PM is prepared to work within the TeleDiaFoS system,but it could be used as a device that sends data to any e-mailuser. It can be a physician or other person interested in thewound healing progress.

Every patient was able to operate the PM and was sendingsuccessfully the foot images and measurement data. Datatransmissions were lost, because of weak GSM signal, in thecase of seven images from the total of 386, that is, 1.8%. Thoseimages were retrieved from the backup folder of the PM.

There were 231 files containing the measurement data thatwere sent to the CCS, and there were no problems concerningtransmissions of those files.

A device of similar functionality as the PM, the Vincent 50,has been developed in The Netherlands.16 It was designedalso to send foot pictures from the patient’s home to themedical team in order to evaluate the state of the foot. Themain differences between the PM and the Vincent 50 are:

1. The PM takes the pictures of 200 dpi resolution, whichis two times higher.

2. The PM is able to send the measurement data as BG andBP (the Vincent 50 does not send any measurementdata).

3. The PM requires a unique disinfection procedure; wewere not informed about the Vincent 50 disinfectionprocedure, if any.

Our earlier research revealed that patients found the PMeasy to use and gave them a sense of safeness because ofawareness that the wound state has been evaluated by themedical team.13 The patients were also glad to be releasedfrom travel to the clinic in order to evaluate the foot wound.Travel to the outpatient clinic is accompanied by stress, whichwas confirmed by some patients. This way the patient’scomfort of living is increased.

Prevention of the occurrence of foot ulcers is even moreimportant than monitoring the wound area. There are somereports on foot temperature monitoring in preventing footulceration. Lavery et al.17 concluded that a difference in feettemperature larger than 2.28C (48F) is a possible symptom ofoncoming ulceration. The temperature measurements arerelatively uncomplicated and can be performed by the patientat home. When monitoring of patients who previously did notexperience wound ulceration is considered, there is a risk of

low patient compliance in such monitoring, because the pa-tients are unaware of the seriousness of the wound develop-ment and its consequences. The patient’s compliance will behigher in preventing foot ulcer recurrence, and in the case ofsuch patients the foot temperature monitoring would be ef-fective.18

The cost–benefit analysis of using the PM is related to thedecrease in frequency of visits of the patient to an outpatientclinic. When the process of wound healing is accepted by thephysician, the patient does not need to arrive for a visit. Thereare time and money savings for both the patient and thedoctor. Another issue concerns the assumption that as time ofthe wound healing becomes shorter, the physician can reactfaster to unacceptable progress in the wound healing. Shortertime of the wound healing gives measurable savings. Themost important issue is that a healed wound means no needfor foot amputation, and that is the most important cost sav-ing. The International Diabetes Federation has stated that theeconomic cost of a diabetic foot ulcer is thought to be between$7,000 and $10,000 US, and where healing is complicated andamputation required, this cost may increase to as much as$65,000 US per person.19

A certain limitation of this article is the lack of a random-ized controlled trial in which patients with and without PMwould be surveyed. Such a study is required to determine thedevice efficacy in DFS treatment. The strength of this article isthe fact that we are presenting in detail a device able to pro-vide home telemonitoring of DFS patients, which is very easyto operate and provides the medical team with useful infor-mation regarding foot status and metabolic control of thepatient.

The PM revealed its usefulness in home telemonitoringbecause the wound pictures sent from the patient’s homeenable the assessment of wound healing progress and there-fore give the physician a chance to change the treatment if thepercentage wound area reduction is not 10% or more in thefirst week of treatment or 40% after 4 weeks. The use of the PMmay enable reducing the number of foot amputations in DFSpatients.

Acknowledgments

The work has been supported by research grant 3 T11E04929 from the Polish Ministry of Science and Higher Education.

Author Disclosure Statement

No competing financial interests exist.

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Address correspondence to:Piotr Foltynski, Ph.D.

Institute of Biocybernetics and Biomedical EngineeringPolish Academy of Sciences

4, Trojdena StreetWarsaw, Poland 02-109

E-mail: pfoltynski@ibib.waw.pl

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