Vital signs monitoring and patient Tracking over a ... · Vital signs monitoring and patient...

66 JohnshopkinsApLTechnicALDigesT,VoLume27,number1(2006)

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VitalsignsmonitoringandpatientTrackingoveraWirelessnetwork

Tia Gao, Logan K. Hauenstein, Alex Alm, David Crawford, Cassius K. Sims, Azmat Husain, and David M. White

atientsatadisasterscenecangreatlybenefitfromtechnologiesthatcontinuouslymoni-tortheirvitalstatusandtracktheirlocationuntiltheyareadmittedtoahospital.Wehavedesignedanddevelopedareal-timepatientmonitoringsystemthatintegratesvitalsignssensors,locationsensors,adhocnetworking,electronicpatientrecords,andwebportaltechnologytoallowremotemonitoringofpatientstatus.Thissystemwillfacilitatecom-municationamongprovidersatthedisasterscene,medicalprofessionalsatlocalhospitals,publichealthpersonnel,andspecialistsavailableforconsultationfromdistantfacilities.

INTRODUCTIONsteadyadvancesinwirelessnetworking,medicalsen-

sors, and interoperability softwarecreateexcitingpos-sibilities for improving thewayweprovide emergencycare in prehospital situations. The Advanced healthand Disaster Aid network (AiD-n) being developedatApLexploresandshowcaseshowtheseadvancesintechnologycanbeusedtoassistvictimsandrespondersintimesofemergency.ThisarticlecoversasubsetofthetechnologiesintheAiD-n.

The Department of homeland security (Dhs)defines a disaster as any incident that challenges theresources of the local community. The overwhelmingnumber of patients requiring urgent care at a disastersite is a significant challenge for responders. Triaging,monitoring, and tracking patients at a disaster sceneare critical tasks in the rescueprocess.unfortunately,

current methodologies for these tasks are often inef-ficient for mass casualty situations. below, we addresssomemajordeficiencieswiththesemethodologies.

Whenfirstrespondersonthesceneofamasscasu-alty incident become overwhelmed with the numberofpatientstobetracked,theymayrequestsecondaryaidfromotherlocalunitsorneighboringjurisdictions.however,thereisoftenasignificanttimedelaybeforeaidarrives;itisnotunusualforfirstresponderstowaituptoanhour for secondaryaid.Duringthiswaitingperiod, patients cannot be monitored and trackedefficientlyby theunderstaffed crew.To alleviate thisproblem,respondersneedresourcesthatallowthemtotrackandmonitoralargenumberofpatientsuntiladdi-tionalhelparrives.Furthermore,differentjurisdictionsneed to be able to access disaster information from

JohnshopkinsApLTechnicALDigesT,VoLume27,number1(2006) 67

ViTALsignsmoniToringAnDpATienTTrAcking

neighboring jurisdictions so they can work togethereffectively.

oneproposedsolutionhasrecentlybeenpushedbyDhsand theAssociationofpublicsafetycommuni-cationsoffices: toenableallfirst responderdisciplines(ems,fire,andpolice) touse interoperablecommuni-cations equipment (e.g., handheld radios) to exchangedisasterinformation.Today,communicationsequipmentineachdisciplineoperatesonitsownradiofrequencies,which makes communications among first respond-ersnearly impossible.Theneedfortheproposedcom-municationsystemisundoubted.however,iftheradiofrequenciesbecomecrowdedwith toomanyusers, thecommunicationssystemscouldfail.inthesesituations,valuable patient information cannot be shared andeffectivepatientcarebecomesaproblem.itisessentialthatthecommunicationtechnologybescalabletothehighusagedemandsofmasscasualtydisasters.

Anothercurrentmethodologyistomonitorpatientsusingpaper-based triage tags (Fig.1),whicharecolor-codedtodesignatetheseverityofthepatients’injuries.patients classified as red are considered to need themost immediate attention, followed by patients classi-fiedas yellow.patients classifiedas greenare the leastseverely injured.patients are classifiedasblack if theyaredeceasedorexpectedtodie.Thesetagshavemanyobviousproblems.First, it is difficult for responders toupdate the color designation easily. in addition, theyprovidelittleroomformanuallyrecordingthepatients’vital signs and chief complaints, which are essentialpiecesof information.Finally, reading the tagscanbedifficult because patient information recorded undertimepressureisoftenillegible.

For all of these reasons, current methodologies inemergencyresponseareerror-proneandburdensomeforthemedics.ApLhasdesignedanddevelopedtechnology-basedsolutionstoalleviatetheseproblems.Thesetech-nologiesfacilitatecollaborativepatientcareinemergencyresponseandrelievetheworkloadofeachresponder.Asa result, our solutions could significantly increase thequalityandquantityofpatientcareandmoreefficientlydeliver patients to the hospital. our technology-basedsolutionsincludethefollowingcomponents:

• electronictriagetagswithsensors• Awirelessadhocmeshnetwork• prehospitalpatientcaresoftware• Asecurewebportal• AhandheldpDA

inthisarticle,webrieflydescribethesecomponents,discussthemethodologiesbehindthem,anddetailtheirimplementation.

OVERVIEW ourelectronictriagetagswithsensorscontinuously

monitor the vital signs and locations of patients until

theyareadmittedtoahospital.WecallthistechnologyVitalmote.Vitalmoteenablesmedicstoefficientlytrackthelocationoflargenumbersofpatients.Furthermore,itgivesmedicsimmediatenotificationsofanychangesinpatient status, such as respiratory failure or cardiacarrest.Thesesensorssolvetheproblemswithpapertagsmentionedabove.Theycanalsodramatically improvethetime-consumingprocessofmanuallyrecordingvitalsignsontohard-copyprehospitalcarereportsandthenconvertingthereportsintoelectronicformat.

Thewirelessadhocmeshnetworktransmitspatientinformation to a central station and guarantees con-nectivitybetweenpatientsandproviders,eveninmass

Figure 1. Current paper-based triage tag.


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casualtyincidents.Theadvantagesofusingameshnet-workarereliabilityandtheabilitytosupportvastnet-works, suchasonethatwouldbecreatedinadisasterwhenalargenumberofpatientswouldbetaggedwithVitalmotes. This technology would help reduce theamountofinformationthatneedstobecommunicatedverballywithcurrentradiocommunicationsdevices.

The prehospital patient care software with algo-rithms continuously monitors patients’ vital signs andalertsfirstrespondersofcriticalchanges.Thissoftwarewillhelpalleviatethecurrentproblemoffirstrespondersbecomingoverwhelmedbythelargenumberofpatientsduringmass-casualtydisasters.

The secure web portal allows authenticated userstocollaborateand share real-timepatient informationandwillalso facilitatecommunicationacrossdifferentresponderdisciplinesandjurisdictions.

The handheld pDA is used by paramedics to col-lect and reportvaluablepatient information,which isthentransmittedinrealtimetotheAiD-nserver.Thisdevice will help solve the problem of current paper-basedtriagetagshavinglittleroomtorecord,andasaresultbeingillegible.Thisdeviceiscalledthesurveil-lanceandincidentreportingpDA(sirp).

METHODOLOGY During health emergencies there is little tolerance

for system errors and poor usability designs. Throughthe use of standards-based software and best-of-breedhardware,ourgoalistodeliverasystemthatisscalable,reliable,anduser-friendly.

ourpatientmonitoringand tracking system,Vital-mote,buildsuponthecodeblueprojectfromharvarduniversity.1 codeblue is a distributed wireless sensornetwork for sensing and transmitting vital signs andgeolocationdata.Figure2illustratesthecurrentproto-types.Awearablecomputercommonlyknownas“smartdust”ora“mote”isattachedtothepatient’swristandformsanadhocwirelessnetworkwithaportabletabletpc.Wehaveintegratedseveralperipheraldeviceswiththemote,includinglocationsensorsforbothindoorandoutdooruse,apulseoximeter,abloodpressuresensor,andanelectronic triage tag.Theelectronic triage tagreplaces the paper triage tag and allows the medic tosetthetriagecolorwiththepushofabutton.Themotealso has onboard memory for storing patient medicalrecords.

AsshowninFig.2,themotecontinuouslytransmitspatientinformationtothefirstresponder’stabletdevice.The transmission uses the Tinyos Active messagesprotocol,whichisbasedontheieee802.15.4standard.2Themotewasoriginallydevelopedattheuniversityofcalifornia,berkeley,inthelate1990s.sincethen,ithasgainedsignificantinterestfromacademiaandindustryfor its ability to provide low-power, cost-effective, andreliable wireless networks for monitoring applications.

our mote prototype uses the micAZ platform fromcrossbowTechnology.itispoweredbytwoAAbatter-iesandconsumesroughly20mAwhenactive,resultinginabatterylifetimeof5–6daysofcontinuousoperation.itusesasingle-chipradiowithamaximumdatarateof76.8kbpsandapracticalindoorrangeofapproximately20–30m.

Thesystemisdesignedtorequirelittlesetuptime.Amediccarriesmanymotepackagesanddistributesthemtothepatients.eachmoteispreattachedwithapapertriagetag,whichactsasbackupiftheelectronictriagetag fails. When the patient is first triaged, the medicstraps the mote wristband on the patient, places thefinger sensoron thepatient’s finger, and sets theelec-tronic triage tag to the patient’s triage category. Thebloodpressuresensorisanoptionalmodule,whichthemedic may put on select patients who need the addi-tionallevelofmonitoring.Themoteautomaticallystartstransmittingdata to themedic’s tabletpc.The tablet

EVDO

Internet

EVDO

Figure 2. Patient information flow.



pcisharnessedtothefirstresponderinaweatherproofandanti-glarecasing.

Weintegratedthesewearablesensorswithaprehospi-talpatientcaresoftwarepackage(michAeLs)createdby the opTimus corporation. michAeLs runs onthefirstresponder’stabletpc.WemodifiedmichAeLstoautomatically recordandanalyze thepatient’svitalsignsandalertthefirstresponderofabnormalchanges.michAeLsalsotransmitspatientinformationinrealtime toacentral server thathosts themedical recorddatabase.michAeLscanwrite thepatient’smedicalrecordonto themote, allowing the information tobestoredlocallywiththepatient.Whenthepatientboardstheambulance,themediconboardcanloadtheinfor-mationfromthepatient’smotebacktothemichAeLssoftware.

Thetabletpcrequiresanetworkconnectiontocom-municatewiththecentralserver.Toachievethiscon-nectivitywehaveusedVerizon’seVDocoverageintheWashington, Dc, metropolitan Area. our tablet pcsuseeVDowireless cards to attainbroadbandcellularinternetconnectivityfromanywhereintheregion.

Wehavealsobuiltawebportaltoconnectwiththepatientrecorddatabaseandmakethereal-timepatientinformationaccessibletousersfrominternetbrowsers.This toolwillbeusedbydifferentparticipants in theemergency response team, such as emergency depart-mentpersonnel,whoneedthisinformationtopreparefor the incoming patient, or public health personnel,who need to understand the situation and assess theadditionalresourcerequirements.

effectivehealthcarerequiresaccesstopatientdatathat are generally stored on heterogeneous databasesystems. integration of patient data is a significantchallenge facedbythehealthcarecommunity. inourimplementation,weareable toconnect twodisparatesystems,thatis,thepatientrecorddatabaseandthewebportal, through the use of well-defined web services.patientinformationistransmittedoversoAp,asecureandencryptedformofXmL.TheWsDL(WebserviceDefinitionLanguage)forthesewebservicesispublishedtoacommunityofauthorizedusers.Thiswebservice-based approach for intersystem communication givesoursoftwaretheflexibilitytooperatewiththird-partysoftwareinthefuture.

IMPLEMENTaTION

VitalMote SensorsVitalmotesensorsareportablelightweightelectronic

triagetagsthataredesignatedbyparamedicswithred/yellow/green/black lights based on the severity of thepatient’s condition. They provide four functionalities:vitalsignsmonitoring,locationtracking,medicalrecordstorage, and triage status tracking.Weare integratingthree types of noninvasive vital signs sensors: a pulse

oximeter,abloodpressuresensor,andathree-leadekg.Thepulseoximeterattachestothepatient’sfingerandmeasuresheartrate(hr)andbloodoxygenation(spo2)level(Fig.3).Acuffpressuresensoronthepatient’supperarmmeasuressystolicanddiastolicbloodpressure.Theekgleadsarepackagedinastickypad,whichcanbeappliedtothepatient’schest.

We also integrated two types of location sensingcapabilities:agpstoprovidegeolocationandanindoorlocationdetectionsystemtoprovidelocationwherethegpssignalcannotbereached.Thegpssensorallowsmedics to trackpatientswhoareoutdoors, e.g., at thesceneoftheemergency,withanaccuracyof3mcircularerrorprobable(cep).Theindoorlocationsystem,basedonthemoteTrackprojectdevelopedatharvarduniver-sity,requirestheinstallationoflocationbeacons,3whichare being placed at a designated auxiliary care centernearWashington,Dc.patientsareadmittedtoanaux-iliarycarecenterifnearbyhospitalshavereachedtheiroccupancycapacities.Atanauxiliarycarecenter,whichcanoftenbeshortonstaffandoverfilledwithpatients,thepatients’vital signswill continue tobemonitoredbyoursystem.Theabilitytotrackthelocationofthepatientsindoorswillbeaveryusefulfeatureforhelping

Figure 3. VitalMote with pulse oximeter.


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medicsquicklyfinda specificpatientwhoseconditionhasdeteriorated.

Withalltheperipheraldevicesturnedon,thepulseand oxygenation are reported every second, the gpslocation is reported every 5 min, and the blood pres-sureisreportedevery15min.Thebatterylifetimeoftheoverallsystemisapproximately6h.Thebloodpressuresensoristhemostpower-hungryperipheral;whenitisnotused,thebatterylifeoftheoveralldeviceincreasesto1–2days.

Vital Signs Monitoring algorithmAusbtransceiverispluggedintoalaptopforvital

signsmonitoring,map-basedpatienttracking,andpre-hospitalpatientcarereporting.softwareonthetabletdevicereceivesreal-timepatientdatafromthemoteandprocessesthedatatodetectanomalies.ifthepatienthasapreviously enteredmedical record, information fromthatrecordisusedinthealertdetectionalgorithm.Table1 shows a partial list of physiological conditions thatcausealerts.Thealgorithmusesadditionalinformationsuchaspatientageandheighttoadjustitsthresholds.ifadditionalinformationisnotavailable,thealgorithmusesasetofdefaultvalues.

Prehospital Patient Care SoftwareThetabletpcregularlytransmitspatientdata(vital

signs, location, triage color) and alerts for multiplepatientstothedatabaseviaawirelessnetwork.ifnet-work connectivity is unavailable, the patient monitorandalertsystemonthetabletpccontinuestooperate.

When an anomaly is detected in the patient vitalsigns,themedic’ssoftwareapplicationgeneratesanalertin theuser interface.Figure4 showsa listofalerts in

Table 1. alert detection parameters.4–7

Alerttype Detectionparameter

Lowspo2 spo2<90%a

bradycardia hr<60bpma

Tachycardia hr>100bpma

hrchange |Dhr/5min|>19%hrstability max.hrvariability frompast4readings>10%bpchange systolicordiastolic change>611%aThese default values are adjusted based on additioninput.

Figure 4. Screenshot of patient monitoring software. The first sidebar on the left shows a list of alerts for all patients, and the second sidebar shows a list of patients sorted by their priority level. The top right panel shows that three types of vital signs read-ings are available for this patient: heart rate, oxygen saturation, and blood pressure. The top right buttons show functions: Turn Alerts Off, Ring Patient Audio, Write PCR to Mote (transmits patient information to the mote), and Set Patient Baseline (adjusts vital signs analysis thresholds based on patient values).



thegui(graphicaluserinterface).Themediccanalsoselect a “ring patient Audio” feature that will soundabuzzerandblinkanLeDonthemote.Allalertsarelistedinsidetheleftpaneltomakemultiplealertseasiertomanage.

Web-based Information PortalThis web-based information portal is an effective

emergencyresponse informationsystemtosupport theneed for multiple parties to share information aboutpatients’ status and locations. our web-based infor-mation portal allows different types of users to accesspatient information in real time.Whenauser logs in,theinformationdisplayedtothatparticularuserisman-aged by group-level permissions. The portal has threegroupsofusers:

1. emergencydepartmentpersonnellogintotheportalto retrieve information about the patients who arebeingtransportedtotheirhospital.

2. incident commanders log in to the portal to seesummaries of patients at the disaster scene. sincepatientsaretrackedbytheVitalmotes,theincidentcommanderscan review thenumberofpatients foreach triage color, allowing them tomake informed

Figure 5. Web page portal for the incident commander showing patient locations. Clicking on one of the flags shows real-time video of that location, as seen in the bottom right of the screen.

requests for additional medical supplies and per-sonnel and to properly allocate available resources(Fig.5).

3. medicalspecialists,oftenlocatedatdistantfacilities,may be called on to give treatment instructions tothe medics at the scene. They log in to view real-timemedicaldataofthepatientsbeingtreated.Theycan also review the triage colors of patients at thescene toverify that thepatientshavebeen triagedcorrectly.

Surveillance and Incident Reporting PDa sirpisahandheldunitformedicalfieldpersonnelto

collectandreportclinicalinformationonsickorinjuredpeople during large public events. The device (Fig. 6)contains a wireless transmitter and a patient medicalhistorycardreader.sirpwirelesslytransmitsdatatotheAiD-nserverandtootherdatabases(includingasyn-dromic surveillance database). sirp allows emergencyrespondersto

• recordtheessentialinformationonapatientatthedisaster scene, including chief complaint, apparentsyndromes, gender, age, current location,and loca-tion at the time of injury or onset of illness. sirp


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Figure 6. SIRP triage screen displayed on the PDA for medical providers.

contains a patient’s medical history card reader tohelpexpeditetheprocess.

• collectotherdiseaseinformationattheevent,suchas animal sicknesses, apparent environmental haz-ards,weatherconditions,andmore.

• record and review incident information, e.g., haz-ardousmaterials,mapsofmarkedareasofthedisasterscene,etc.

aSSESSMENT OF BENEFITSThe potential benefits of the AiD-n project are

clear when aspects of the proposed system are com-paredagainstaspectsof the response systemcurrentlyin place. consider a representative scenario in whichVitalmotewouldbeusedtoalertparamedicsofsuddencardiacarrest (scA)victimsat adisaster scene.Defi-brillatingthevictimcantreatscA.eachminutethatdefibrillation isdelayed reduces thevictim’s chanceofsurvivalbyabout10%.8

Assume a disaster situation where one paramedicismonitoring20patientsinhisareawithyellowtags.The medic must continuously monitor each patient,

sohe spends30 soneachand15 s travelingamongthem.Allpatientsarelyingdown,soapatientwhoseheart has gone into scA and passes out would notlooknoticeablydifferentfromotherpatientswhoarelyingdown.Table2 shows the calculateddelay timeuntiltreatmentofthescApatientforacontrolcase,where a medic manually monitors the patients, andtheVitalmotecase,whereamedicmanuallymonitorsthepatientsandVitalmotealsomonitorsthepatients.Vitalmotealertsthemedicofthepatientwhohasgoneinto scA. calculations show that Vitalmote signifi-cantlyimprovedtheexpectedsurvival.

ToensuretheapplicabilityoftheAiD-nsysteminthefield,theAiD-nteamhassolicitedevaluationsoftheproposedsystemdesignfromactualemsfieldpersonneloftheArlingtonFireDepartment,includingcaptains,platoon chiefs, and paramedics with a cumulative 90yearsofemsexperience.Theywereinitiallyquestionedontheircurrentpracticesandthedifficultyassociatedwithvarioustaskswhenrespondingtomultiplepatientincidents.Thetwotasksthattheyconsideredthemostdifficultweretriagingthevictimsandkeepingtrackofthepatientsdesignatedasredormostcritical.inaddi-tion,locatingvictimsandcommunicatingpatientinfor-mationweretwotaskswhichweredescribedashavinganappreciableamountofdifficulty.

Afterconductingademonstrationofthedevicetotheemspersonnel,aquestionnairewascompletedbyeachparticipantabouttheusefulnessofthedifferentfeaturesof the AiD-n. The AiD-n system itself was receivedpositively,andmuchoftheinputtakenfromthepartici-pantshasalreadybeenimplementedintothemostrecentdesignupdate.Theaspectsofthesystemconsideredmostusefulwerethefeatureallowingpatientstobelistedbycolor, the Vitalmote, and the ability to buzz motes tolocatetheminacrowdofpatients.Thevitalsignsalarmmonitor,whichalertswhenvitalsignsfalloutofacer-tainrange,wasalsoratedhighlyinitsusefulness.

From the questionnaires and conversations withvariousemspersonnel,theapplicabilityandusefulnessoftheAiD-nsysteminthefieldhavebeensubstanti-atedtoadegree.minordesignchanges for thesensorweresuggestedsuchasreducingitssizeandenhancing

Table 2. VitalMote increases patient survival rate.

case control Vitalmote

Worst 15-mindelay 45-sdelay <10%survivalrate >90%survivalrateAverage 7-mindelay 30-sdelay ≈30%survivalrate >90%survivalratebest 20-sdelay 20-sdelay >90%survivalrate >90%survivalrate



thebrightnessofthelight.Thesechangesarecurrentlybeingaddressed.

CONCLUSION aND FUTURE WORKThe AiD-n system has great potential in improv-

ing problems in today’s emergency response system,especiallythoseassociatedwithmasscasualtydisasters.Whiledesigningoursystem,wecollaboratedextensivelywith medical professionals to identify their greatestneeds.Thekeyactivitiesthatcouldbeimprovedusingthe technology are patient monitoring, patient recordgeneration, and remote patient record review. AiD-nhas constructed hardware and software prototypes toaddresstheseneedsandshowspromiseinimprovingtheefficiencyofemergencypersonnelfortheseactivities.

All technologies have limitations and cannot pro-videtheirbenefitsunderallcircumstances.Whennewtechnology is introduced into theemergency responsearena, its limitationsaswellas itscapabilitiesmustbeconsidered.becauseof thechaoticnatureofemergen-cies,oursystemfacesthedifficultyofoperatinginsitu-ationsthatchallengeinstrumentationdesignedforusein the controlled environment of a clinical situation.For example, the pulse oximeter sensor used by AiD-ncannotfunctiononpatientswithfingernailpolishornail fungus. Furthermore, in cold temperatures and/orhighaltitudes,thebodyrespondsthroughvasoconstric-tion in theperipherals; in thiscase,bloodflowto thefingers isrestrictedanddoesnotregisteraccuratelyonthepulseoximeter.

Weacknowledgethatourpatientmonitoringfeaturewill not be useful in all situations. in a mass-casualtydisaster, when the medics must triage many casualtiesquickly,therewillbenotimetorespondtoalertsuntilall patients have been triaged. The medics whom weinterviewed expect our monitoring system to be mostusefulforpatientswhohavebeentriagedandarewait-ing for ambulances. They can then use our system to

prioritizethepatientswhoneedtobetransportedtoacarefacility.

The AiD-n system has many benefits over thecurrent paper-based system of triaging and trackingpatients, as shown by our hypothetical scenario andopinions of experienced ems personnel. our systemis currentlybeingprepared tobeused ina simulateddisaster exercise. This exercise will be conducted inpartnership with suburban hospital, Johns hopkinspediatricTraumacenter,andanauxiliarycarecenter.During this exercise, comparisonsbetween theeffec-tivenessofcurrentdisasterresponsemethodologiesandtheAiD-nsystemwillbeconducted.

AcknoWLeDgmenTs:Thankstostevebabin,Tagcutchis,brianFeighner,mattkim,andharoldLehman,fortheirmedicalexpertise;martysikesandronstick-ley for insight into first responders’ line of work; andJeffreychavisandDavidWhitefortheirprojectguid-ance.ThisworkissponsoredbythenationalLibraryofmedicinethroughgrantn01-Lm-3-3516.

reFerences 1Lorincz, k., malan, D., Fulford-Jones, T. r. F., nawoj, A., clavel,

A.,etal.,“sensornetworksforemergencyresponse:challengesandopportunities,”IEEE Pervasive Comput.,16–23(oct–Dec2004).

2hill,J.,szewczyk,r.,Woo,A.,hollar,s.,culler,D.,andpister,k.,“system Architecture Directions for networked sensors,” in Proc. 9th Int. Conf. on Architectural Support for Programming Languages and Operating Systems (ASPLOS 2000),Acmpress,pp.93–104(2000).

3Lorincz, k., and Welsh, m., A Robust, Decentralized Approach to RF-Based Location Tracking,Tr-19-04,DivisionofengineeringandAppliedsciences,harvarduniversity,cambridge,mA(2004).

4Palatini, p., “need for a revision of the normal Limits of restingheartrate,”Hypertension33(2),622–625(Feb1999).

5schwartz,g.r.,Principles and Practice of Emergency Medicine,ritten-housebookDistributors,kingofprussia,pA(1999).

6behrman, r. e., Nelson Textbook of Pediatrics, W.b. saunders co.,philadelphia,pA(2000).

7chobanian, A. V., bakris, g. L., and black, h. r., “The seventhreportof the Jointnationalcommitteeonprevention,Detection,evaluation,andTreatmentofhighbloodpressure,”Hypertension42,1206–1252(Dec2003).


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THE aUTHORS

cassiusk.sims

Logank.hauenstein

Tiagao

Tia Gao,projectmanageroftheAdvancedhealthandDisasterAidnetwork(AiD-n),leadstheAiD-nTeam.ms.gaoisamemberoftheAssociateprofessionalstaffinApL’snationalsecurityTechnologyDepartment.shejoinedtheLabo-

ratoryin2004afterworkingformedtronicinc.ms.gaoguidestheAiD-nTeaminareasinclud-ingvitalsignsignalprocessing,softwarearchitecturedesign,andusabilityengineering.Logan K. HauensteinisamemberofApL’sAssociateprofessionalstaffinthenationalsecurityTechnol-ogyDepartment.inadditiontoleadingtheserver-levelsoftwaredevelopmenteffort,mr.LoganarchitectedtheAiD-nwebservicesandthedisasterdatamodelsharedamongtheAiD-nclientsoftwarecomponents.alex alm(notpictured)isanelectricalengineeringandphysicsstudentat

Vanderbiltuniversityanddevelopedthepatientmonitoringalgorithmsandsoftware.David Crawford(notpictured)isacomputerengineeringstudentattheuniversityofmaryland,collegepark,anddevelopedtheportabledevicesforpatienttriage.Cassius K. Sims isacomputerengi-neeringstudentatTheJohnshopkinsuniversityanddevelopedthewebportalsoftwarefortheAiD-n.azmat Husainisamedicalstudentattheuniversity of maryland school of medicine and coordinates usabilityreviewsandrequirementsdefinitionfortheproject.David M. White istheprincipal investigatorof theAiD-n.TheAiD-nTeam’sworkhas

Davidm.White

Azmathusain

resultedinmultiplepatenteddisclosuresandoveradozenpeer-reviewedinternationalpublications.The team can be contacted through the projectmanager,[email protected].

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