PILOT TEST OF A PROPOSED CHEMICAL/BIOLOGICAL/RADIATION/NUCLEAR-CAPABLE MASS CASUALTY TRIAGE SYSTEM

David C. Cone, MD, Donald S. MacMillan, MA, PA, EMT-P, Vivek Parwani, MD,Carin Van Gelder, MD

ABSTRACT

Introduction. Existing mass casualty triage systems do notconsider the possibility of chemical, biological, or radio-logic/nuclear (CBRN) contamination of the injured patients.A system that can triage injured patients who are or may becontaminated by CBRN material, developed through expertopinion, was pilot-tested at an airport disaster drill. The studyobjective was to determine the system’s speed and accuracy.Methods. For a drill involving a plane crash with release oforganophosphate material from the cargo hold, 56 patientscenarios were generated, with some involving signs andsymptoms of organophosphate toxicity in addition to phys-ical trauma. Prior to the drill, the investigators examinedeach scenario to determine the “correct” triage categoriza-tion, assuming proper application of the proposed system,and trained the paramedics who were expected to serve astriage officers at the drill. During the drill, the medics usedthe CBRN triage system to triage the 56 patients, with two ob-servers timing and recording the events of the triage process.The IRB deemed the study exempt from full review.Results. The two triage officers applied the CBRN systemcorrectly to 49 of the 56 patients (87.5% accuracy). One patientintended to be T2 (yellow) was triaged as T1 (red), for anover-triage rate of 1.8%. Five patients intended to be T1 weretriaged as T2, and one patient intended to be T2 was triagedas T3 (green), for an under-triage rate of 10.7%. All six under-triage cases were due to failure to recognize or account forsigns of organophosphate toxidrome in applying the triagesystem. For the 27 patients for whom times were recorded,triage was accomplished in a mean of 19 seconds (range 4-37,median 17).Conclusions. The chemical algorithm of the proposed CBRN-capable mass casualty triage system can be applied rapidlyby trained paramedics, but a significant under-triage rate(10.7%) was seen in this pilot test. Further refinement andtesting are needed, and effect on outcome must be studied.Key words: triage; emergency medical services; emer-gency medical technicians; disaster planning; hazardous sub-stances.

PREHOSPITAL EMERGENCY CARE 2008;12:236–240

Received July 19, 2007, from the Division of EMS, Section of Emer-gency Medicine, Yale University, School of Medicine, New Haven, CT(DC, DM, VP, CVG). Revision received October 22, 2007; accepted forpublication October 23, 2007.

Address for correspondence: David C. Cone, MD, Yale EmergencyMedicine, Suite 260, 464 Congress Avenue, New Haven, CT 06519,Tel 203-785-4710, Fax 203-785-3196. E-mail: david.cone@yale.edu

Presentation: NAEMSP Annual Meeting, Tucson AZ, January 20,2006.

doi: 10.1080/10903120801907620

INTRODUCTION

Existing mass casualty triage systems, such asthe U.S.-based Simple Triage And Rapid Transport(START) system1 and the British Triage Sieve,2 donot consider the possibility of chemical, biological, orradiologic/nuclear (CBRN) contamination of the in-jured patients. It is possible, however, that victims ofcertain types of disasters may have both “conventional”traumatic injuries, and CBRN contamination or conta-gion. For example, victims of a “dirty bomb” explosionmay have various blast injuries, and may also be con-taminated with radiologic material. Patients caught ina stampede out of a crowded arena following an overtrelease of a bioagent may have physical injuries in ad-dition to exposure to the bioagent.

In a recent concept paper, we proposed a system thatcould be used to triage injured patients who are ormay be contaminated by CBRN material.3 This system,which was developed primarily through expert opin-ion, given the lack of data on the subject, is built on theSTART system, primarily due to how widespread theuse of the START system is in the US. The study we de-scribe in this paper represents the first pilot field test ofone of the algorithms of the proposed CBRN-capabletriage system. The study objectives were to examinethe accuracy and speed with which trained paramedicscould apply this triage algorithm at a live disasterdrill.

METHODS

Study Design

For a scheduled airport disaster drill involving a mockplane crash with release of organophosphate materialfrom the aircraft’s cargo hold, 56 patient scenarios weregenerated, with some involving signs and symptomsof organophosphate toxicity in addition to physicaltrauma. The scenarios had been generated by the air-port staff for a crash drill three years earlier, and theinvestigators simply altered several of the scenarios toadd evidence of an organophosphate toxidrome (mio-sis, wheezing, etc.). The relevant clinical information foreach scenario (vital signs, degree of respiratory distress,a list of injuries, etc.) was printed on a large laminatedcard that was fastened to each of the 56 victims (localhigh school students). The victims were moulaged asappropriate for their injuries, and were briefly coached

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Cone et al. CBRN MASS CASUALTY TRIAGE 237

by the moulage officers and the investigators on howto best play out the information on the cards.

Paramedics who might be assigned to serve as triageofficers at the drill (as determined by looking in advanceat shift schedules for the day of the drill) were trained toproficiency in the CBRN triage system by the principleinvestigator two to three weeks prior to the drill. Twotraining sessions were held, each two hours in length,with a total of 12 paramedics trained. The paramedicswere each given two hours of continuing medical edu-cation credit for their time at the training sessions, butno other payment or incentive was offered.

Each training session consisted of a didactic presen-tation of the CBRN-capable system (including howand why it had been developed), followed by prac-tice with a number of pre-written clinical scenarios oncommon contaminants, until the principal investiga-tor and paramedics agreed that proficiency had beenreached. The complete CBRN-capable system (includ-ing all four algorithms) was taught, and the paramedicswere not told which type of scenario (chemical, biolog-ical, radiologic, or nuclear) would be used in the crashdrill. While an organophosphate case was among theten clinical scenarios used in the training sessions, theparamedics were not told that the drill would involvean organophosphate. Instead, they were told that theywould need to be alert for signs of one of the four typesof situations, and apply the appropriate algorithm; thenature of the contamination was not announced duringthe drill, but instead was discovered and dealt with bythe participating responders.

Study Setting

Paramedic training was conducted at the New Haven(CT) Regional Fire Training Academy. The disasterdrill was conducted at Tweed-New Haven Airport,a small regional airport with two commercial carri-ers providing nine scheduled flights per day, as wellas general aviation and a fixed-base operator of air-craft services. The drill was designed to meet the Fed-eral Aviation Administration’s requirements for a livedisaster drill every third year. The airport straddlesthe cities of New Haven (population approximately125,000) and East Haven (approximately 28,000). Eachcity has a fire department providing advanced life sup-port (ALS) first response. A single commercial am-bulance service provides BLS and ALS transport forboth cities. Paramedics from all three agencies weretrained in the CBRN-capable triage system, to ensurethat whichever paramedics were assigned to the triagefunction by the incident commander would be able touse the system. The airport’s Aircraft Rescue & Fire-fighting (ARFF) team provides fire suppression only,and not patient care, and thus was not involved in thestudy.

Outcome Measures and Analytical Methods

Prior to the drill, each patient’s clinical scenario was ex-amined by three of the investigators (DCC, DSM, CVG)to determine the “correct” triage categorization, as-suming proper application of the chemical/trauma al-gorithm of the CBRN-capable triage system. (Figure 1)There were no disagreements among the investigatorsregarding which triage category was “correct,” likelybecause the clinical details given for each case weredesigned to address the clinical exam and data neededto complete the algorithm. The triage category actuallyassigned by the paramedic, as recorded by observersduring the drill, was compared to this standard,allowing for calculations of accuracy, over-triage,and under-triage. The observers also timed the triageprocess, using a stopwatch to time the interval betweenthe paramedic arriving at the patient, and the assign-ment of a triage category (T3/minor/green, T2/delayed/yellow, T1/immediate/red, or T4/expectant/black). The observers, who were blindedto the purpose of the study, were firefighters from anearby fire department that was not participating inthe drill. They wore orange reflective vests labeled“Fire Research” to clearly identify their role.

The data collected by the observers were enteredinto an Excel (Microsoft, Redmond WA) spreadsheet.Simple descriptive statistics were used to analyze thefindings.

Study Approval

The study was deemed exempt from full review bythe Yale University Human Investigations Committee(protocol #27536).

RESULTS

The drill was conducted in a driving rainstorm, and the56 mock patients were thus kept on the two school busesthat served as the aircraft fuselage. No patients wereplaced on the runway or adjacent field. The incidentcommander assigned the first two paramedics to arriveon scene to serve as triage officers. One started at thefront of the first bus, and the other at the back end of thesecond bus, and they worked toward the middle. Untilall 56 of the patients were triaged, these paramedics didnot perform any other roles.

The two triage officers applied the chemical/traumaalgorithm of the CBRN system correctly to 49 of the56 patients (87.5% accuracy). Figure 2 outlines the in-tended and assigned triage categories for the 56 pa-tients. One patient intended to be T2 (yellow) wastriaged as T1 (red), for an over-triage rate of 1.8%. Fivepatients intended to be T1 were triaged as T2, and onepatient intended to be T2 was triaged as T3 (green),for an under-triage rate of 10.7%. All six under-triagecases appear to have been due to failure to recognize or

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FIGURE 1. Chemical/trauma triage algorithm (reprinted with permission from: Cone DC, Koenig KL. Mass casualty triage in the chemical,biological, radiological, or nuclear environment. Eur J Emerg Med. Dec 2005;12(6):287–302.)

account for signs of organophosphate toxidrome in ap-plying the triage system, as these patients were triagedcorrectly based on their injuries alone. In other words,the triage categories assigned by the paramedics forthese six cases where the triage categories that would re-sult if the basic trauma algorithm3 (instead of the chem-ical algorithm) of the proposed system were used.

Due primarily to the congestion on the buses, the ob-servers were only able to record triage times for 27 ofthe patients. Triage was accomplished in a mean of 19seconds (range 4–37, median 17).

DISCUSSION

These data suggest that trained paramedics can applythe chemical/trauma algorithm of the proposed CBRN-capable mass casualty triage system quickly and fairlyaccurately; however, we saw a higher rate of under-triage than we would have liked. We are aware of nostandards for rates of over- and under-triage in masscasualty events, though for triage of the single traumapatient (i.e., determining whether or not a given traumapatient needs the resources of a trauma center, or caninstead be transported to a closer non-trauma-centerfacility), it is generally recommend that under-triage

be 5% or less, even if this results in over-triage of asmuch as 50%.4,5

While both over- and under-triage are problematicin the mass casualty incident setting, under-triage islikely the greater clinical concern. Over-triage can dis-tract the attention of providers from others who mayneed it, can consume scarce resources unnecessarily,and may delay transport unnecessarily for patients ata triage level below the over-triaged patients. CurrentAmerican College of Surgeons trauma systems recom-mendations indicate that over-triage in the disaster set-ting “can adversely impact patient care and survival,”though no supporting data or references are provided.5

Under-triage, on the other hand, has the potential todeprive patients of needed attention, whether that befield treatment, or transport. Mass casualty triage sys-tems are generally designed such that the T1 or “red”category captures those patients with conditions thatwill rapidly threaten life. Erroneously assigning a pa-tient with such injuries to a lower triage category mayresult in unnecessary morbidity or mortality, thoughwe are aware of no research quantifying this relation-ship. We suspect that the under-triage seen in our studyresulted from the failure of the paramedics to accountfor the organophosphate toxidrome, since the assigned

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Cone et al. CBRN MASS CASUALTY TRIAGE 239

FIGURE 2. Intended and actual triage categories.

triage categories were otherwise correct if based solelyon the traumatic injuries. It may be that training needsto focus more on the CBRN aspects of these patients;perhaps the paramedics are already fairly proficient athandling the conventional injuries, given prior trainingon START or other systems, but the lack of prior train-ing or experience triaging CBRN-exposed patients maynecessitate more education and practice than was pro-vided in this study. However, it is also possible that theproblem lies not with the training in CBRN recognition,but in the triage algorithm itself. Further study will beneeded to more accurately determine the cause of theunder-triage we saw.

There are several important limitations to this study.First, the paramedics had all been trained within a fewweeks of the drill. It is unclear how they would haveperformed had there been a longer interval betweentraining and the drill. The role of skill deteriorationand periodic refresher training will need to be exam-ined. While skill retention has been studied for suchEMS skills as airway management6 and CPR and AEDuse,7−9 we are aware of only a single study examin-ing the retention of triage skills. Baez and colleaguesdeveloped an internet-based training program to teachthe START system to Latin American EMS personnel,and assessed skill retention with a follow-up test onemonth after initial training.10 While they found goodskill retention, it seems likely that longer-term out-comes will need to be studied, particularly for skillssuch as mass casualty triage that are rarely used.

Second, we used only paramedics in the triage role,and due to the logistics of the drill, only two of the 12trained medics actually got to triage patients. Resultsmight differ in areas that use EMT-Basics, EMS physi-cians, or other types of providers as triage officers. Somefeel that the personnel with the highest level of train-ing should provide triage, while others feel that thosepersonnel should provide treatment, not triage. This isunresolved, and different systems handle the issue dif-ferently. Our results might also have been different hadlarger numbers of medics triaged the patients. Third,we only studied the chemical/trauma algorithm in thispilot test, and the biological, radiation, and nuclear al-gorithms remain untested.

Perhaps the most important limitation is that no out-comes were studied, aside from the speed of triage,which itself was quite limited by the low capture rateof times. It is essentially impossible to study clinical

outcomes in a drill scenario, and we are aware of nostudies that have attempted this. Even in the setting ofa real mass casualty incident or disaster, it is very diffi-cult to study how specific interventions (such as triage,field treatment, and mode of transport) influence clin-ical outcomes. There is no agreement regarding whatoutcomes should be studied, with the literature con-taining a mix of resource-based11,12 and physiologic13

parameters. Even if the standard that we used (i.e. thetriage category assigned by the investigators14) is clin-ically accurate, we do not know whether correctly as-signing patients to triage categories (using this or anyother system) will actually improve outcomes.

Having said this, it seems reasonable to assume thathaving some sort of systematic approach to assessmentand prioritization of patients is better than not. We sim-ply don’t yet know precisely what approach we oughtto be taking. Recent efforts to provide a more scientificand data-driven approach to the development of a newtriage system are encouraging,15,16 and a recent abstractsuggests that outcomes research may be feasible.17

Hopefully these efforts and others signal the beginningof a more scientific look at mass casualty triage.

CONCLUSIONS

The chemical/trauma algorithm of the proposedCBRN-capable mass casualty triage system can be ap-plied rapidly by trained paramedics, but a significantunder-triage rate was seen in this disaster drill pilottest, likely due to failure to recognize the toxidrome in-volved in the drill scenario. Further refinement and test-ing are needed, perhaps with emphasis on the CBRNportion of the system and/or recognition of CBRN con-tamination, and effect on outcome must be studied.The other algorithms (biologic, radiologic, and nuclear)must also be studied, in an effort to arrive at a compre-hensive, valid, and clinically meaningful system.

The authors thank the administrative staff of Tweed-New Haven Air-port for their assistance, the North Madison Volunteer Fire Companyfor providing the observers, and Dr. Kristi Koenig for her review ofthe manuscript.

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