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A regional review of air medical transports for fatal motor vehicle crashes
ORIGINAL RESEARCH
A Regional Review of Air Medical Transports for Fatal Motor Vehicle Crashes Elizabeth A. Garthe, MHS, 1 Nicholas K. Mango, BSME, 1 Brad Prenney, MS, MPA 2
1. Garthe Associates, Marblehead, Mass. 2. Bureau of Health Quality Management, Massachusetts Department of Public Health, Boston, Mass. Address for correspondence: Elizabeth Garthe, Garthe Associates, 7 Skinner's Place, Suite B, Marblehead, MA 01945-4614; [email protected] Key Words: air medical, automatic crash notification, event data recorders, fatal analysis reporting system, linkage, population based, utilization review Copyright © 2000 by Air Medical Journal Associates 1067-991 X/2000/$8.00 + 0 Reprint no. 74/1/108562 doi: 10.1067/mmj.2000.108562 Disclosure: The study described in this article was conducted by Garthe Associates under the auspices of the Bureau of Health Quality Management 'with funding from the Massachusetts Department of Public Health. Acknowledgments: The authors thank the following agencies for their assistance or interest: the Registry of Motor Vehicles, the Massachusetts FARS analyst for the National Highway Traffic Safety Administration, the Helicopter Utilization Review Committee, the MDPH Division of Vital Statistics, the Division of Health Care Finance and Policy, air medical services Boston MedFlight and LifeFlight, and the Governor's Highway Safety Bureau.
Air Medical Journal
Editorial comment by Brad Prenney, Deputy Director, Bureau of Health Quality Management for the Massachusetts Department of Public Health This article describes a study conducted under the auspices of the bureau to review the use of air medical services for fatal motor vehicle crashes (MVCs) for one Massachusetts EMS region in 1996. This study was prompted in part by anecdotes and perceptions of possible overutilization of air medical services magnified by a neighboring state's efforts to stop these services. The bureau embarked on an effort to objectively assess the use of air medical services using a population-based approach. Therefore, the study was designed to focus on a "high risk" group consisting of all the people involved in fatal motor vehicle crashes (MVCs) rather than just the people who were recorded by the services as being transported. Investigators initially set out to answer the question, "How many of the people involved in fatal MVCs qualify for and/or receive air medical transport?" We believe that the approach taken was both unique and fair, and the quest to answer one question has led to others. Abstract
This article presents study results from an assessment of the performance of the air medical (and advanced life support) components of the EMS system in response to fatal motor vehicle crashes. Results are presented for one of Massachusetts' five EMS regions, including the finding that air medical transports
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are involved in 20% of the fatal crashes for the region and transport 11% of the involved individuals. Although the study focused on air medical utilization, it also identified issues related to the future implementation of motor vehicle automatic crash notification (ACN) and telematics that could relay crash severity data from onboard computers (eg, event data recorders) to auto manufacturers' help centers or state emergency call centers. This technology will place new demands on state EMS systems. To meet the challenges posed by these technological changes, states will need to assess the type and number of EMS services required to respond to ACN motor vehicle crashes and develop methods to determine what level of service to deploy based on the information relayed from the vehicles. An initial step in this evaluation process is to determine the current use of EMS resources to place planned system changes and demand into context.
Introduction The Massachusetts Department of Public Health (MDPH) conducted a study of all people involved in fatal motor vehicle crashes (MVCs) for one EMS region in 1996 using an index case, multiple database linkage method to r~ view all air medical transports used. Massachusetts has one of the only statewide, population-based databases for civilian (nonmilitary, nonpolice) rotor-wing air medical transports in the country. The purpose of the study was to review the utilization of air medical (and ground) EMS services and identify new 83
Injury Pyramid for every 5 0 0 people involved in MVCs 1 fatality 8 requiring hospitalization 26 requiring medical treatment •~ "
85 slightly injured
Source:
NHTSA,CODES
- 380 uninjured
ways to reduce deaths and disabilities from MVCs. The MDPH's Bureau of Health Quality Management (BHQM) oversees the Office of Emergency Medical Services (OEMS), whose mission is to ensure that effective prehospital medical care is provided in the state. In 1997, OEMS convened a helicopter utilization review committee (HURC)--a multidisciplinary committee with representatives from regulatory, provider, and professional organizations--to assist and advise the MDPH on issues related to air medical service utilization. To help guide the field decision to request helicopter transport, the HURC developed recommended statewide air medical triage guidelines in 1997. Two Massachusetts air medical services currently cover a state of about 6 million people and 8300 square miles with four helicopters, two for each service.1 The state runs approximately 200 miles from east to west and 100 miles north to south and includes Cape Cod and the islands of Nantucket and Martha's Vineyard. Statewide Air Medical Data for 1996 In this study, an air medical mission was defined as each time a helicopter lifted (or was diverted in flight) as the result of a request for services. In 1996, 2547 patient transport missions were flown and 2582 patients were transported. 2 Thirty-five flights transported 84
more than one person. Types of missions included scene, in which the helicopter flies to a nonhospital landing site for patient pickup; interfacility, the pickup is made at a hospital landing site and involves the transport of a patient admitted to a hospital; and modified scene, a patient (but not an inpatient) picked up from a hospital landing site, although he or she might have received care in the ED. Usually, modified scene transports occur within a few hours of a patient being brought to an ED. Scene and modified scene missions are situations in which patients do not have complete access to inpatient hospital resources; as such, they generally are medical emergencies that are evoMng or being stabilized.
The "Index Event" Method for Utilization Review A goal of the MDPH and the HURC was to establish a method for reviewing both air medical utilization and the associated triage guidelines. Reviews of overor underutilization can be complex, controversial, and have serious ramifications. In the recent past, a neighboring state moved to terminate all air medical operations after an unfavorable evaluation result. ~ Utilization studies must consider many factors, including case severity, distance (by air or by ground) from a hospital, weather conditions, treatment facility credentials, availability of advanced life support (ALS) ground ser-
vices versus air medical transport, triage criteria, and outcome. General consensus in the literature holds that overutilization of some types of services may be preferable to underutilization. For example, the American College of Surgeons states that up to 50% overtriage of trauma patients to trauma centers may be required to maintain an acceptable level (5% to 10%) of undertriageJ The disadvantage of overutilization of air medical transport is the extra cost of the transport compared with ground ambulance and lack of helicopter availability for appropriate transports. To appropriately evaluate air medical utilization, all potential opportunities for utilization must be reviewed. This evaluation requires the underlying statewide (or regional) need for air medical services to be established as a "denominator." Although the air medical data for the state is a census (ie, populationbased), carrying out utilization analysis based on geographic region alone does not supply the denominator. The need for air medical transport on a geographic basis is related to many factors, including town population size and density, landing sites, and residents' ages and activities. This complexity makes determining an accurate denominator of need very difficult. To overcome the complexity of defining the denominator, the authors developed an alternative utilization approach. The method generates its denominator by collecting a statewide census of all patients with identifying "index events" that qualify them as possible air medical candidates. These events are independent of actual air medical transport. Selecting populations based on index events makes it possible to observe the response of the whole EMS system and place the air medical response in perspective. Because the HURC previously had agreed to adopt certain index events as part of the recommended statewide air medical triage guidelines, selecting one of these events has the added benefit of supplying data to gauge the effectiveness of that element in the guidelines. The statewide air medical triage guidelines include index events that specify cases in which air medical transport may be appropriate. One example is a fatal MVC in which an injured occu-
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Air Medical Journal
Figure 2
Statewide Fatal MVCs by Region 1996 - 392 Crashes D ^ . ; ^ . ~, Regi¢ n=!
Region B n =76
Region I n = 100
n =59
-igure 3
Police Injury Severity for Region C 1996, 59 crashes, 151 people involved Severity unknown n=2
Fatal n=59
Possible n=15
Nonincapac n=21 Incapacitated n=26
pant was in the same passenger compartment as the fatality. The assumption (with some logical exceptions) that a helicopter may be called to the scene of a crash in which at least one person was killed is reasonable. This index event, the fatal crash, was selected as the first group to study for air medical utilization. Other triage criteria events likely to be found in fatal crashes include prolonged extrication, ejection, and pedestrians struck and thrown more than 15 feet. This study retrospectively applied the triage criteria guidelines recommended in 1998 by the HURC to 1996 fatal crash data to establish baseline air medical utilization figures. Fatal M-VCs also are a good starting point because they involve people at all injury levels, and fatal injuries are related to other injury severities as shown by the Injury Pyramid in Figure 1.5 This Air Medical Journal
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relationship suggests a logical pathway for future extension of the index events to other crash severities. To identify the index cases for analysis, data on statewide fatal MVCs were required. An analysis was conducted using the Fatal Analysis Reporting System (FARS), a special database maintained by the National Highway Traffic Safety Administration (NHTSA) and based on police crash reports (PCRs).6 FARS contains data on a census of fatal traffic crashes within the 50 states, the District of Columbia, and Puerto Rico. To qualify for inclusion, a crash must involve a motor vehicle traveling on a trafficway customarily open to the public and must result in the death of an occupant of a vehicle or a n o n m o t o r i s t within 30 days of the crash. For 1996, FARS lists 41,907 people killed in 37,351 crashes for an overall death
July-September 2000
rate of 16/100,000 population. 6 In 1996, M a s s a c h u s e t t s ' death rate of 6.8/100,000 was the lowest in the United States. 6 Figure 2 shows the 392 crashes by EMS region. This article presents the air medical utilization results for EMS Region C, which had 59 index event crashes. The FARS data for these crashes provide the date and location, weather conditions, some EMS arrival times, type of crash, type of roadway, and speed limit among other elements. Eighty-three vehicles were involved in the 59 index crashes, and for each vehicle FARS records part of the vehicle identification number (VIN), make, model, year, body type, estimated damage, fire occurrence, impact point (initial and principal), whether the vehicle was towed from the scene, most harmful event, travel speed, and other information. 6 The 59 index crashes also include information on 151 involved people, of whom 59 died. FARS collects demographic information about everyone involved in a fatal crash (killed, injured, or uninjured), which is why the number of involved people greatly exceeds the crash count. Data on the people involved include age, gender, air bag availability and function, drug and alcohol use (for drivers and pedestrians), restraint use, and seating position. 6 To designate injuries, FARS uses "KABCOU,"a single attribute injury system. KABCOU is designed for quick use at the scene by police officers completing PCRs. 6 As Table 1 shows, only one rating is assigned per person. The KABCOU injury ratings for the 151 people involved in the 59 index c r a s h e s are shown in Figure 3. Although FARS contains much useful information, it also has limitations. Among these are the lack of specific in-
Table • Police Injury Rating System K A B C O U
or or or or or or
4 3 2 1 0 5 6 9
= = = = = = = =
Killed Incapacitating injury Nonincapacitating injury Possible injury No injury U n k n o w n if injured Died before crash Unknown
85
:igure 4
Linkage of Fatal Crash Index Events All Deaths
Detailed Injuries, ICD-9-CM
Place of Death Status at Death ICD-9 Codes Demographics
62 Total Deaths 59 Trauma Deaths 1 Non-trauma 2 Non-Residents
Vital
Crash Data Vehicle Data Police Severity
Statistics
Multiple Cause of Death Data
Length of Stay Charges
Hospital
Severity & ISS
Case Mix
NHTSA FARS l
HCFP
(Inpatient) Data
Fatal Level MV Crash
Deaths: 26 Inpatient
13 DOA 10 Outpatient 13 at Scene
Data
First Responder Ambulance Hospital
Massachusetts I
Narrative 63 Crashes 62 Crash Reports 88 Vehicles 163 Persons 108 Transported 76 Serious Inj.
59 Crashes 83 Vehicles 151 Persons 106 Transported 59 Deaths in 30 days 1 Death unconfirmed
Crash Reports
T ALS Ambulance Run Reports
Origin/Dest. TLmes
Transport Details Vital Signs
y
I -
DPH Air Medical
Transport Data
Missions
Vital Signs
18 Patients Transported from 16 Crashes
Narrative 27 Persons with ALS Runs
Linking Index Events with Air Medical and O t h e r Databases
Sources of complementary data can be added by linking unique variables from different sources to tell the complete story of an event. 5 Linkage takes advantage of data already collected by different entities; therefore, it does not require new data collection efforts. Candidates for linkage to this study's index events included the air medical database, EMS ALS patient care reports, ED records, hospital case mix discharge data and autopsy reports, or vital statistics data. Direct linkage was used for this study so that individual medical record review could be undertaken if required. This linkage method is different than others that result in match probabilities. Massachusetts is believed to be the first 86
2 Aborts 1 Cancel 17 Transport 10 Scene 2 Mad. Scene 5 Interfacility
Demographics
jury information, the identity and type of facility where the people involved were treated, physiological measurements at the crash scene, treatment procedures and costs, and EMS transport times for each person, all of which are desirable for utilization review. Another limitation is that FARS does not record what type of transport occurred, such as air medical, basic life support (BLS), or ALS. Although FARS provides a starting point for the index event study, complementary information must be sought from other sources.
Landing Zone Destination
state to conduct linked index case analysis to review air medical transports. The FARS index cases plus an additional five sources of linkage data ultimately were selected for the fatal crash index event study: • Vital statistics records, MDPH • Police crash reports, Registry of Motor Vehicles (RMV) * ALS patient care reports, MDPH • Air medical services data, MDPH • Hospital case mix data, Division of Health Care Finance and Policy Figure 4 illustrates the linkage sources, the key data elements they contain, and initial linkage results. A description of each linkage database's characteristics follows. Vital s t a t i s t i c s data. T h e s e data are
collected by the states and centralized at the National Center for Health Statistics. M a s s a c h u s e t t s maintains its death records in electronic format, and these data provide information on the location of death, identity and type of medical facility, time of death, underlying cause of injury (external cause of injury codes), and multiple cause of injury (ICD-9 nature of injury codes).7 In some cases, anatomic location of injury (eg, chest), organ involved (eg, heart) or type of lesion (eg, laceration) can be ascertained from the vital statistics data. The data on people who were dead at the scene or dead on arrival (DOA) at a treatment fa-
cility are particularly useful. In these cases, detailed information is not available from other medical sources, such as the ED, hospital case mix, or trauma registry data. Vital statistics data are a natural enhancement to the FARS' limited injury information, and linking these data sources on a national basis is described elsewhere by the authors, s Crash reports. These data are collected by the police for all crashes with bodily injury or property damage in exc e s s of $1000 and operators when the police are not present. The data are collected severally within 30 days of the crash by the RMV from all police departments in the state. Compliance is required by state law. A subset of data elem e n t s from the p a p e r copy of the police-reported crashes are entered into the RMV's statewide computerized database, and these data include information on the crash, vehicles, and demographics of the people involved. 9 For the index case study, the computerized data variables were augmented with information from the p a p e r reports, including the crash narrative, the emergency response (first responder, police, EMS, etc.), and where the injured people were transported. The crash report often was a rich source of details about the number of people involved, their injury levels, occupant seating position and vehicle, the EMS response, whether air medical
July-September 2000 19:3 Air Medical Journal
transport was used, and to which hospitals the injured were transported. ALS patient care reports. These reports sometimes are centralized by EMS region and generally are not computerized. ALS reports provided additional information about the patients' injuries and vital signs at the scene, initial treaixnent, time at scene, transport time, and receiving hospital. BLS patient care reports were not linked as part of the initial study but are intended to be in the future. Air medical t r a n s p o r t data. This statewide database includes time/date of flight request, referring agency, mission start time/date, type of transport, type of medical e m e r g e n c y , arrival time/date, facility patient transported to/from, and clinical m e a s u r e m e n t s (vital signs, Glasgow coma score, etc.) Hospital case mix database. This computerized database includes records for every inpatient from every hospital in the state. Compliance is required by regulation. The case mix data is derived from patient discharge summaries and medical records. Data elements include demographics, hospital ID number, nature of admission (emergent, urgent, elective, etc.), source of admission (ED, clinic referral, transfer, etc.), date of admission, outcome (discharge to home, transferred, died, etc.), discharge diagnoses (ICD-9-CM codes), E-codes, procedures, payers, and charges. ~° Case mix data provides detailed information on the type of injury or medical problem, charges, and outcome. Hospital ICD-9CM injury codes can be used to estimate severity (threat to life) for trauma patients, a capability of great interest for outcome review. T M Using linked data from the above sources, the authors profiled the index events selected from FARS. Summary results and information on selected cases from the linked data are presented in the following section. R e s u l t s of I n d e x E v e n t L i n k a g e
The first result of the linkage process was that additional index events were identified. The group of original FARS events and the event group after linkage are summarized in Table 2 for the total number of crashes, deaths, and people involved. The added events are a result of the different goals of the FARS and
I'able :
Summary
of Index Cases
Index cases from FARS Crashes Deaths People involved
Index cases after linkage Crashes Total deaths Deaths in Mass. vital statistics People with ambulance ALS run reports Air medical missions 18 people, 2 aborts, 1 cancellation People transported to treatment facilities Total people involved
vital statistics databases. FARS collects data on potentially preventable fatal MVCs occurring on public roadways with deaths that occur within 30 days. However, the system also excludes data for certain people and crashes, including crashes on private property and vehicular homicide. 6 Vital statistics, on the other hand, collects data on all deaths. Because air medical response might be required for crashes on private property and vehicular homicides, the FARS index cases can be complemented with these additions. Table 2 compares the index cases before linkage (in FARS) with those identified after linkage. The linkage matched 56 of the 59 FARS index case deaths with vital statistics records. One of the 56 cases linked was categorized as a fatal heart attack, which occurred just before the crash, rather than a traumatic death from a MVC (FARS would not consider this event to be a motor vehicle fatality). Two of the three unmatched cases involved deaths of nonMassachusetts residents. Massachusetts vital statistics will not contain these cases because they would be counted in their home state's data. The remaining case was listed in FARS as "killed" at the scene, but no death certificate was found in the vital statistics data. The Massachusetts resident involved was transported by air to a trauma center and likely survived. As a result, the number of deaths in the original FARS index case group was reduced by 1 to 58. However, all 59 of the original index cases were retained in the index group.
Air Medical Journal 19:3 July-September 2000
Number 59 58 151
Number 63 62 60 27 17 108 163
Further review of the vital statistics data using MVC-related E-codes identified four MVC-related deaths not listed in FARS. Three of t h e s e - - a vehicular homicide, a death after 30 days, and a crash on private property--are excluded under FARS coding rules. The fourth case qualified for inclusion in FARS but was overlooked. Three of the four additional vital statistics deaths linked to crash reports, and these events involved six people. No crash report exists for the fourth death (the private p r o p e r t y crash), but it is believed that two people were involved, including the decedent. All four of these additional cases could have resulted in air medical transport requests and therefore were added to the index group, bringing the total index cases to 63 (59 + 4). The four additional cases increased the deaths from 59 to 62, including correction for the one person mentioned in the preceding paragraph for whom no death certificate was found (59- 1 + 4 = 62). The vital statistics review, together with other additional information, led to an upward revision in the number of people involved in the 63 index events from 151 to 163. The increase resulted from unknown drivers involved with hitand-run crashes, the extra four cases not originally included, and people noted in the crash reports who were excluded from FARS (eg, drivers outside their vehicle at the time of the crash). It was possible to link ALS ambulance patient care reports for 27 of the 163 people (17%). ALS may have been deployed for additional people, but the 87
records were not available; neither were records on BLS requests and patient care reports. Table 2 shows that air medical services transported 18 of the 163 people involved (11%) as either scene, modified scene, or interfacility transfers. In one event, the same helicopter transported two people; in three events, more than one helicopter was involved. From reviews of the police reports, ALS patient care reports, and air medical missions, at least 108 (66%) of the 163 people involved in the fatal crashes were transported to hospitals directly from the scene; this figure does not include the 13 people dead at the scene but does include 11 people DOA at the hospital, some of which could be bodies transported to hospital morgues. Air medical services transported 18 (17%) of the 108 people taken to hospitals versus 11% of the 163 involved people. The request records, which were recorded for only one service, showed no "skids down" misses or stand downs for any of the 63 index events. Three air medical missions resulted in "skids up" scrubs, including two aborts and one cancellation. The cancellation patient was flown later as a modified scene transport, but neither abort patient was transported by air. The 17 missions, two aborts, and one cancellation were related to 16 (25%) of the index events. Air medical services were not requested for the remaining 47 (75%) of the crashes for one service, and the request status for these crashes is unknown for the second service. Table 3 summarizes location of death and transport information of the people who died. Of the total 62 deaths, 13 died at the scene. Of the remaining 49 fatalities, nine people were transported by helicopter: two were DO& two died in the ED, and five died as inpatients within 1996 according to vital statistics records. The remaining 40 fatalities were trans~able :
Location of death Scene DOA Outpatient/ED Inpatient Total
88
ported by ground: 11 were DOA, eight died in the ED, and 21 died as inpatients. The index cases included 89 people with "killed" or "serious" police injury ratings at the scene. Eliminating the 13 people who died at the scene leaves 76 people with serious injuries who did not. Of that group, 18 (24%) were transported by helicopter. The universe of people involved or injured in nonfatal MVCs is not included in the study sample; therefore, death rates can not be calculated. However, the individual DOAs and ED and inpatient deaths can be reviewed by an appropriate panel to study EMS response, medical treatment, and outcome. Linking the inpatient hospital case mix data has been completed to determine additional details, such as injury severity, procedures, hospital charges, and disposition (home, rehabilitation hospital, long-term care, etc.). An effort was made to profile the injury severity for any person who was hospitalized as an inpatient subsequent to a fatal crash, whether or not he or she was recorded as being transported directly from the scene. These results will be reported in a subsequent article. Utilization Insights Resulting from the Index Event Linkage Review of the linked crash data provided examples of a variety of situations in which air medical services were not used at the scene but: • A mechanism of injury existed that was consistent with the current triage guidelines. • Multiple serious casualties were involved. • A helicopter was requested for the scene, but the mission was aborted or canceled. Also identified were situations in which air medical services were used at
L o c a t i o n of D e a t h by T r a n s p o r t S t a t u s Air medical transport-yes
Air medical transport-no
Total
0 2 2 5 9
13 11 8 21 53
13 13 10 26 62
the scene or later for inteffacility transfers but: • Multiple casualties were involved and multiple air medical transports were requested, but not all patients were transported by air. • Coordination was required between both air medical services to meet the needs of multiple people injured at the same crash. The average number of seriously injured people was greater than two, yet the helicopters generally were configured to transport one patient. • Scene pickups were canceled by the requester and reinstated later for inteffacility transfers. Conclusions about the appropriateness of EMS response and air medical transport cannot be drawn from the linkage data presented in this article alone. A peer review process would be necessary to provide in-depth review of the deployment of EMS and air medical resources to these crashes. Implications for the Impact of New Technology on the EMS System New technology in automotive design has led to the development of systems to capture or record, through onboard computers, the characteristics of a crash event. Some crash characteristics that may be associated with risk of serious injury are air bag deployment, "crash pulse," delta V (change in velocity), and rollover. The technology currently exists in certain m a k e / m o d e l vehicles to record this important information through event data recorders. In addition, some vehicles have the capability to transmit some information about a crash event to a call or help center generally operated by an automobile manufacturer. These call centers can then relay basic information about crash events to state 9-1-1 or EMS systems. General Motors' On-Star system is an example of an automatic crash notification (ACN) system; it has been designed to recognize a crash event that results in air bag deployment. Deployment then opens a line of communication between the vehicle occupants and the call center by which the center can talk with the occupants to determine if they need assistance. In a situation in which the occupants cannot communicate (eg,
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19:3 Air Medical Journal
unconscious), the call center refers informarion about the crash (eg, the car location) to a state 9-1-1 or EMS system. ACN is a subset of telematics, which refers to the c o n s u m e r products, services, and supporting systems that deliver information, communications, and entertainment to vehicles and mobile devices. The study suggests that a ~ t u r e ACN s y s t e m could be u s e d to c a p t u r e and transmit critical crash, vehicle, and perhaps o c c u p a n t characteristics to state EMS systems. With the use of appropriate guidelines, the EMS systems potentially could triage the crashes by optimal level of response needed: air medical, ALS, or BLS. This prioritization could save valuable response time and potentially better match the level of resources needed to the s e v e r i t y of c r a s h injuries that oc-
curred. The ultimate goal is to save lives and reduce disabilities from crashes. However, this type of ACN s y s t e m might be expected to deploy air medical or ALS services to 100% of the types of c r a s h e s p r e s e n t e d in t h i s a r t i c l e - - a trend that may present significant operational challenges to state EMS air medical systems and require different guidel i n e s and l e v e l s of r e s o u r c e s t h a n currently are used. Fatal crashes are just the "tip of the iceberg," however. F o r every fatal crash, several serious crashes occur, approximately eight to 10, that would place their own demands on air medical and EMS systems. Conclusion This article describes an index event
approach to air medical utilization re-
v i e w u s i n g data linkage. Fatal M V C s were used as the index events for this article. The approach identifies an entire population based on an aspect of the air m e d i c a l t r i a g e c r i t e r i a g u i d e l i n e and then collects detailed information available on that group through data linkage. Results were shown for all fatal MVCs from one of Massachusetts' five EMS regions for 1996. As a result of the regional findings, t h e M a s s a c h u s e t t s G o v e r n o r ' s Highway safety B u r e a u has funded an exp a n s i o n of t h i s s t u d y to c o l l e c t s t a t e w i d e l i n k e d d a t a for 1996 fatal MVCs. T h e B u r e a u of Health Quality and M a n a g e m e n t will collaborate with t h e G H S B on t h i s i n i t i a t i v e . T h e statewide results are expected to be reported later in 2000.
References
1. Bureau of the Census. Vital statistics of the United States, 1995. Washington (DC): Government Printing Offices;1995. 2. Massachusetts Department of Public Health, Bureau of Health QualityManagement & Office of Emergency Medical Services. Air medical services database. 1996. 3. Vermont Health PolicyCounciland Health Care Authority regulatory rulings regarding air medical transport within Vermont. 1996 Feb 27, April5. 4. American College of Surgeons Committee on Trauma. Resources for optimal care of the injured patient, 1999. Chicago:The College;1998. 5. Johnson S, Walker J. The crash outcome data evaluation system. NHTSA Technical Report. DOT HS 808 338. Washington (DC): National HighwayTrafficSafetyAdministration; 1996Jan.
6. Department of Transportation, National Highway Traffic SafetyAdministration. Fatal analysis reporting system, 1996. 7. Massachusetts Department of Public Health, Registry of Vital Records and Statistics. Death files. 1996. 8. Mango N, Garthe E. Why people die in motor vehicle crashes: linking detailed causes of death with FARSData. SAE Congress, 1998Feb. 9. Massachusetts Registry of Motor Vehicles. Police and operator crash report data. 1996. 10. Massachusetts Divisionof Health Care Finance and Policy. Hospital case mix and charge database, 1996. 11. Garthe E. The compatibilitybetween the abbreviated injury scale (AIS-80)and the international classification of diseases (ICD-9-CM).Proceedings from the annual conference of the Ameri-
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can Association of Automotive Medicine, San Francisco, California;1981. Quarterly Journal of the AAAM;March 1982. 12. MacKenzie EJ, Steinwachs MD, Shankar B. Classifying trauma severity based on hospital discharge diagnoses: validation of an ICD-9-CM to AIS-85 conversion table. Medical Care 1989;27:412. 13. Garthe E, Mango N. A motor vehicle crash injury specific map--ICD-9-CM to NASS/CDS. Proceedings of the AA.AMAnnual Conference, Orlando, Fla., 1997. 14. Baker SP, O'NeillB, Haddon W Jr, et al. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma 1974;14:187-96.
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A Regional Review of Air Medical Transports for Fatal Motor Vehicle Crashes Elizabeth A. Garthe, MHS, 1 Nicholas K. Mango, BSME, 1 Brad Prenney, MS, MPA 2
1. Garthe Associates, Marblehead, Mass. 2. Bureau of Health Quality Management, Massachusetts Department of Public Health, Boston, Mass. Address for correspondence: Elizabeth Garthe, Garthe Associates, 7 Skinner's Place, Suite B, Marblehead, MA 01945-4614; [email protected] Key Words: air medical, automatic crash notification, event data recorders, fatal analysis reporting system, linkage, population based, utilization review Copyright © 2000 by Air Medical Journal Associates 1067-991 X/2000/$8.00 + 0 Reprint no. 74/1/108562 doi: 10.1067/mmj.2000.108562 Disclosure: The study described in this article was conducted by Garthe Associates under the auspices of the Bureau of Health Quality Management 'with funding from the Massachusetts Department of Public Health. Acknowledgments: The authors thank the following agencies for their assistance or interest: the Registry of Motor Vehicles, the Massachusetts FARS analyst for the National Highway Traffic Safety Administration, the Helicopter Utilization Review Committee, the MDPH Division of Vital Statistics, the Division of Health Care Finance and Policy, air medical services Boston MedFlight and LifeFlight, and the Governor's Highway Safety Bureau.
Air Medical Journal
Editorial comment by Brad Prenney, Deputy Director, Bureau of Health Quality Management for the Massachusetts Department of Public Health This article describes a study conducted under the auspices of the bureau to review the use of air medical services for fatal motor vehicle crashes (MVCs) for one Massachusetts EMS region in 1996. This study was prompted in part by anecdotes and perceptions of possible overutilization of air medical services magnified by a neighboring state's efforts to stop these services. The bureau embarked on an effort to objectively assess the use of air medical services using a population-based approach. Therefore, the study was designed to focus on a "high risk" group consisting of all the people involved in fatal motor vehicle crashes (MVCs) rather than just the people who were recorded by the services as being transported. Investigators initially set out to answer the question, "How many of the people involved in fatal MVCs qualify for and/or receive air medical transport?" We believe that the approach taken was both unique and fair, and the quest to answer one question has led to others. Abstract
This article presents study results from an assessment of the performance of the air medical (and advanced life support) components of the EMS system in response to fatal motor vehicle crashes. Results are presented for one of Massachusetts' five EMS regions, including the finding that air medical transports
19:3 July-September 2000
are involved in 20% of the fatal crashes for the region and transport 11% of the involved individuals. Although the study focused on air medical utilization, it also identified issues related to the future implementation of motor vehicle automatic crash notification (ACN) and telematics that could relay crash severity data from onboard computers (eg, event data recorders) to auto manufacturers' help centers or state emergency call centers. This technology will place new demands on state EMS systems. To meet the challenges posed by these technological changes, states will need to assess the type and number of EMS services required to respond to ACN motor vehicle crashes and develop methods to determine what level of service to deploy based on the information relayed from the vehicles. An initial step in this evaluation process is to determine the current use of EMS resources to place planned system changes and demand into context.
Introduction The Massachusetts Department of Public Health (MDPH) conducted a study of all people involved in fatal motor vehicle crashes (MVCs) for one EMS region in 1996 using an index case, multiple database linkage method to r~ view all air medical transports used. Massachusetts has one of the only statewide, population-based databases for civilian (nonmilitary, nonpolice) rotor-wing air medical transports in the country. The purpose of the study was to review the utilization of air medical (and ground) EMS services and identify new 83
Injury Pyramid for every 5 0 0 people involved in MVCs 1 fatality 8 requiring hospitalization 26 requiring medical treatment •~ "
85 slightly injured
Source:
NHTSA,CODES
- 380 uninjured
ways to reduce deaths and disabilities from MVCs. The MDPH's Bureau of Health Quality Management (BHQM) oversees the Office of Emergency Medical Services (OEMS), whose mission is to ensure that effective prehospital medical care is provided in the state. In 1997, OEMS convened a helicopter utilization review committee (HURC)--a multidisciplinary committee with representatives from regulatory, provider, and professional organizations--to assist and advise the MDPH on issues related to air medical service utilization. To help guide the field decision to request helicopter transport, the HURC developed recommended statewide air medical triage guidelines in 1997. Two Massachusetts air medical services currently cover a state of about 6 million people and 8300 square miles with four helicopters, two for each service.1 The state runs approximately 200 miles from east to west and 100 miles north to south and includes Cape Cod and the islands of Nantucket and Martha's Vineyard. Statewide Air Medical Data for 1996 In this study, an air medical mission was defined as each time a helicopter lifted (or was diverted in flight) as the result of a request for services. In 1996, 2547 patient transport missions were flown and 2582 patients were transported. 2 Thirty-five flights transported 84
more than one person. Types of missions included scene, in which the helicopter flies to a nonhospital landing site for patient pickup; interfacility, the pickup is made at a hospital landing site and involves the transport of a patient admitted to a hospital; and modified scene, a patient (but not an inpatient) picked up from a hospital landing site, although he or she might have received care in the ED. Usually, modified scene transports occur within a few hours of a patient being brought to an ED. Scene and modified scene missions are situations in which patients do not have complete access to inpatient hospital resources; as such, they generally are medical emergencies that are evoMng or being stabilized.
The "Index Event" Method for Utilization Review A goal of the MDPH and the HURC was to establish a method for reviewing both air medical utilization and the associated triage guidelines. Reviews of overor underutilization can be complex, controversial, and have serious ramifications. In the recent past, a neighboring state moved to terminate all air medical operations after an unfavorable evaluation result. ~ Utilization studies must consider many factors, including case severity, distance (by air or by ground) from a hospital, weather conditions, treatment facility credentials, availability of advanced life support (ALS) ground ser-
vices versus air medical transport, triage criteria, and outcome. General consensus in the literature holds that overutilization of some types of services may be preferable to underutilization. For example, the American College of Surgeons states that up to 50% overtriage of trauma patients to trauma centers may be required to maintain an acceptable level (5% to 10%) of undertriageJ The disadvantage of overutilization of air medical transport is the extra cost of the transport compared with ground ambulance and lack of helicopter availability for appropriate transports. To appropriately evaluate air medical utilization, all potential opportunities for utilization must be reviewed. This evaluation requires the underlying statewide (or regional) need for air medical services to be established as a "denominator." Although the air medical data for the state is a census (ie, populationbased), carrying out utilization analysis based on geographic region alone does not supply the denominator. The need for air medical transport on a geographic basis is related to many factors, including town population size and density, landing sites, and residents' ages and activities. This complexity makes determining an accurate denominator of need very difficult. To overcome the complexity of defining the denominator, the authors developed an alternative utilization approach. The method generates its denominator by collecting a statewide census of all patients with identifying "index events" that qualify them as possible air medical candidates. These events are independent of actual air medical transport. Selecting populations based on index events makes it possible to observe the response of the whole EMS system and place the air medical response in perspective. Because the HURC previously had agreed to adopt certain index events as part of the recommended statewide air medical triage guidelines, selecting one of these events has the added benefit of supplying data to gauge the effectiveness of that element in the guidelines. The statewide air medical triage guidelines include index events that specify cases in which air medical transport may be appropriate. One example is a fatal MVC in which an injured occu-
July-September 2000 19:3
Air Medical Journal
Figure 2
Statewide Fatal MVCs by Region 1996 - 392 Crashes D ^ . ; ^ . ~, Regi¢ n=!
Region B n =76
Region I n = 100
n =59
-igure 3
Police Injury Severity for Region C 1996, 59 crashes, 151 people involved Severity unknown n=2
Fatal n=59
Possible n=15
Nonincapac n=21 Incapacitated n=26
pant was in the same passenger compartment as the fatality. The assumption (with some logical exceptions) that a helicopter may be called to the scene of a crash in which at least one person was killed is reasonable. This index event, the fatal crash, was selected as the first group to study for air medical utilization. Other triage criteria events likely to be found in fatal crashes include prolonged extrication, ejection, and pedestrians struck and thrown more than 15 feet. This study retrospectively applied the triage criteria guidelines recommended in 1998 by the HURC to 1996 fatal crash data to establish baseline air medical utilization figures. Fatal M-VCs also are a good starting point because they involve people at all injury levels, and fatal injuries are related to other injury severities as shown by the Injury Pyramid in Figure 1.5 This Air Medical Journal
19:3
relationship suggests a logical pathway for future extension of the index events to other crash severities. To identify the index cases for analysis, data on statewide fatal MVCs were required. An analysis was conducted using the Fatal Analysis Reporting System (FARS), a special database maintained by the National Highway Traffic Safety Administration (NHTSA) and based on police crash reports (PCRs).6 FARS contains data on a census of fatal traffic crashes within the 50 states, the District of Columbia, and Puerto Rico. To qualify for inclusion, a crash must involve a motor vehicle traveling on a trafficway customarily open to the public and must result in the death of an occupant of a vehicle or a n o n m o t o r i s t within 30 days of the crash. For 1996, FARS lists 41,907 people killed in 37,351 crashes for an overall death
July-September 2000
rate of 16/100,000 population. 6 In 1996, M a s s a c h u s e t t s ' death rate of 6.8/100,000 was the lowest in the United States. 6 Figure 2 shows the 392 crashes by EMS region. This article presents the air medical utilization results for EMS Region C, which had 59 index event crashes. The FARS data for these crashes provide the date and location, weather conditions, some EMS arrival times, type of crash, type of roadway, and speed limit among other elements. Eighty-three vehicles were involved in the 59 index crashes, and for each vehicle FARS records part of the vehicle identification number (VIN), make, model, year, body type, estimated damage, fire occurrence, impact point (initial and principal), whether the vehicle was towed from the scene, most harmful event, travel speed, and other information. 6 The 59 index crashes also include information on 151 involved people, of whom 59 died. FARS collects demographic information about everyone involved in a fatal crash (killed, injured, or uninjured), which is why the number of involved people greatly exceeds the crash count. Data on the people involved include age, gender, air bag availability and function, drug and alcohol use (for drivers and pedestrians), restraint use, and seating position. 6 To designate injuries, FARS uses "KABCOU,"a single attribute injury system. KABCOU is designed for quick use at the scene by police officers completing PCRs. 6 As Table 1 shows, only one rating is assigned per person. The KABCOU injury ratings for the 151 people involved in the 59 index c r a s h e s are shown in Figure 3. Although FARS contains much useful information, it also has limitations. Among these are the lack of specific in-
Table • Police Injury Rating System K A B C O U
or or or or or or
4 3 2 1 0 5 6 9
= = = = = = = =
Killed Incapacitating injury Nonincapacitating injury Possible injury No injury U n k n o w n if injured Died before crash Unknown
85
:igure 4
Linkage of Fatal Crash Index Events All Deaths
Detailed Injuries, ICD-9-CM
Place of Death Status at Death ICD-9 Codes Demographics
62 Total Deaths 59 Trauma Deaths 1 Non-trauma 2 Non-Residents
Vital
Crash Data Vehicle Data Police Severity
Statistics
Multiple Cause of Death Data
Length of Stay Charges
Hospital
Severity & ISS
Case Mix
NHTSA FARS l
HCFP
(Inpatient) Data
Fatal Level MV Crash
Deaths: 26 Inpatient
13 DOA 10 Outpatient 13 at Scene
Data
First Responder Ambulance Hospital
Massachusetts I
Narrative 63 Crashes 62 Crash Reports 88 Vehicles 163 Persons 108 Transported 76 Serious Inj.
59 Crashes 83 Vehicles 151 Persons 106 Transported 59 Deaths in 30 days 1 Death unconfirmed
Crash Reports
T ALS Ambulance Run Reports
Origin/Dest. TLmes
Transport Details Vital Signs
y
I -
DPH Air Medical
Transport Data
Missions
Vital Signs
18 Patients Transported from 16 Crashes
Narrative 27 Persons with ALS Runs
Linking Index Events with Air Medical and O t h e r Databases
Sources of complementary data can be added by linking unique variables from different sources to tell the complete story of an event. 5 Linkage takes advantage of data already collected by different entities; therefore, it does not require new data collection efforts. Candidates for linkage to this study's index events included the air medical database, EMS ALS patient care reports, ED records, hospital case mix discharge data and autopsy reports, or vital statistics data. Direct linkage was used for this study so that individual medical record review could be undertaken if required. This linkage method is different than others that result in match probabilities. Massachusetts is believed to be the first 86
2 Aborts 1 Cancel 17 Transport 10 Scene 2 Mad. Scene 5 Interfacility
Demographics
jury information, the identity and type of facility where the people involved were treated, physiological measurements at the crash scene, treatment procedures and costs, and EMS transport times for each person, all of which are desirable for utilization review. Another limitation is that FARS does not record what type of transport occurred, such as air medical, basic life support (BLS), or ALS. Although FARS provides a starting point for the index event study, complementary information must be sought from other sources.
Landing Zone Destination
state to conduct linked index case analysis to review air medical transports. The FARS index cases plus an additional five sources of linkage data ultimately were selected for the fatal crash index event study: • Vital statistics records, MDPH • Police crash reports, Registry of Motor Vehicles (RMV) * ALS patient care reports, MDPH • Air medical services data, MDPH • Hospital case mix data, Division of Health Care Finance and Policy Figure 4 illustrates the linkage sources, the key data elements they contain, and initial linkage results. A description of each linkage database's characteristics follows. Vital s t a t i s t i c s data. T h e s e data are
collected by the states and centralized at the National Center for Health Statistics. M a s s a c h u s e t t s maintains its death records in electronic format, and these data provide information on the location of death, identity and type of medical facility, time of death, underlying cause of injury (external cause of injury codes), and multiple cause of injury (ICD-9 nature of injury codes).7 In some cases, anatomic location of injury (eg, chest), organ involved (eg, heart) or type of lesion (eg, laceration) can be ascertained from the vital statistics data. The data on people who were dead at the scene or dead on arrival (DOA) at a treatment fa-
cility are particularly useful. In these cases, detailed information is not available from other medical sources, such as the ED, hospital case mix, or trauma registry data. Vital statistics data are a natural enhancement to the FARS' limited injury information, and linking these data sources on a national basis is described elsewhere by the authors, s Crash reports. These data are collected by the police for all crashes with bodily injury or property damage in exc e s s of $1000 and operators when the police are not present. The data are collected severally within 30 days of the crash by the RMV from all police departments in the state. Compliance is required by state law. A subset of data elem e n t s from the p a p e r copy of the police-reported crashes are entered into the RMV's statewide computerized database, and these data include information on the crash, vehicles, and demographics of the people involved. 9 For the index case study, the computerized data variables were augmented with information from the p a p e r reports, including the crash narrative, the emergency response (first responder, police, EMS, etc.), and where the injured people were transported. The crash report often was a rich source of details about the number of people involved, their injury levels, occupant seating position and vehicle, the EMS response, whether air medical
July-September 2000 19:3 Air Medical Journal
transport was used, and to which hospitals the injured were transported. ALS patient care reports. These reports sometimes are centralized by EMS region and generally are not computerized. ALS reports provided additional information about the patients' injuries and vital signs at the scene, initial treaixnent, time at scene, transport time, and receiving hospital. BLS patient care reports were not linked as part of the initial study but are intended to be in the future. Air medical t r a n s p o r t data. This statewide database includes time/date of flight request, referring agency, mission start time/date, type of transport, type of medical e m e r g e n c y , arrival time/date, facility patient transported to/from, and clinical m e a s u r e m e n t s (vital signs, Glasgow coma score, etc.) Hospital case mix database. This computerized database includes records for every inpatient from every hospital in the state. Compliance is required by regulation. The case mix data is derived from patient discharge summaries and medical records. Data elements include demographics, hospital ID number, nature of admission (emergent, urgent, elective, etc.), source of admission (ED, clinic referral, transfer, etc.), date of admission, outcome (discharge to home, transferred, died, etc.), discharge diagnoses (ICD-9-CM codes), E-codes, procedures, payers, and charges. ~° Case mix data provides detailed information on the type of injury or medical problem, charges, and outcome. Hospital ICD-9CM injury codes can be used to estimate severity (threat to life) for trauma patients, a capability of great interest for outcome review. T M Using linked data from the above sources, the authors profiled the index events selected from FARS. Summary results and information on selected cases from the linked data are presented in the following section. R e s u l t s of I n d e x E v e n t L i n k a g e
The first result of the linkage process was that additional index events were identified. The group of original FARS events and the event group after linkage are summarized in Table 2 for the total number of crashes, deaths, and people involved. The added events are a result of the different goals of the FARS and
I'able :
Summary
of Index Cases
Index cases from FARS Crashes Deaths People involved
Index cases after linkage Crashes Total deaths Deaths in Mass. vital statistics People with ambulance ALS run reports Air medical missions 18 people, 2 aborts, 1 cancellation People transported to treatment facilities Total people involved
vital statistics databases. FARS collects data on potentially preventable fatal MVCs occurring on public roadways with deaths that occur within 30 days. However, the system also excludes data for certain people and crashes, including crashes on private property and vehicular homicide. 6 Vital statistics, on the other hand, collects data on all deaths. Because air medical response might be required for crashes on private property and vehicular homicides, the FARS index cases can be complemented with these additions. Table 2 compares the index cases before linkage (in FARS) with those identified after linkage. The linkage matched 56 of the 59 FARS index case deaths with vital statistics records. One of the 56 cases linked was categorized as a fatal heart attack, which occurred just before the crash, rather than a traumatic death from a MVC (FARS would not consider this event to be a motor vehicle fatality). Two of the three unmatched cases involved deaths of nonMassachusetts residents. Massachusetts vital statistics will not contain these cases because they would be counted in their home state's data. The remaining case was listed in FARS as "killed" at the scene, but no death certificate was found in the vital statistics data. The Massachusetts resident involved was transported by air to a trauma center and likely survived. As a result, the number of deaths in the original FARS index case group was reduced by 1 to 58. However, all 59 of the original index cases were retained in the index group.
Air Medical Journal 19:3 July-September 2000
Number 59 58 151
Number 63 62 60 27 17 108 163
Further review of the vital statistics data using MVC-related E-codes identified four MVC-related deaths not listed in FARS. Three of t h e s e - - a vehicular homicide, a death after 30 days, and a crash on private property--are excluded under FARS coding rules. The fourth case qualified for inclusion in FARS but was overlooked. Three of the four additional vital statistics deaths linked to crash reports, and these events involved six people. No crash report exists for the fourth death (the private p r o p e r t y crash), but it is believed that two people were involved, including the decedent. All four of these additional cases could have resulted in air medical transport requests and therefore were added to the index group, bringing the total index cases to 63 (59 + 4). The four additional cases increased the deaths from 59 to 62, including correction for the one person mentioned in the preceding paragraph for whom no death certificate was found (59- 1 + 4 = 62). The vital statistics review, together with other additional information, led to an upward revision in the number of people involved in the 63 index events from 151 to 163. The increase resulted from unknown drivers involved with hitand-run crashes, the extra four cases not originally included, and people noted in the crash reports who were excluded from FARS (eg, drivers outside their vehicle at the time of the crash). It was possible to link ALS ambulance patient care reports for 27 of the 163 people (17%). ALS may have been deployed for additional people, but the 87
records were not available; neither were records on BLS requests and patient care reports. Table 2 shows that air medical services transported 18 of the 163 people involved (11%) as either scene, modified scene, or interfacility transfers. In one event, the same helicopter transported two people; in three events, more than one helicopter was involved. From reviews of the police reports, ALS patient care reports, and air medical missions, at least 108 (66%) of the 163 people involved in the fatal crashes were transported to hospitals directly from the scene; this figure does not include the 13 people dead at the scene but does include 11 people DOA at the hospital, some of which could be bodies transported to hospital morgues. Air medical services transported 18 (17%) of the 108 people taken to hospitals versus 11% of the 163 involved people. The request records, which were recorded for only one service, showed no "skids down" misses or stand downs for any of the 63 index events. Three air medical missions resulted in "skids up" scrubs, including two aborts and one cancellation. The cancellation patient was flown later as a modified scene transport, but neither abort patient was transported by air. The 17 missions, two aborts, and one cancellation were related to 16 (25%) of the index events. Air medical services were not requested for the remaining 47 (75%) of the crashes for one service, and the request status for these crashes is unknown for the second service. Table 3 summarizes location of death and transport information of the people who died. Of the total 62 deaths, 13 died at the scene. Of the remaining 49 fatalities, nine people were transported by helicopter: two were DO& two died in the ED, and five died as inpatients within 1996 according to vital statistics records. The remaining 40 fatalities were trans~able :
Location of death Scene DOA Outpatient/ED Inpatient Total
88
ported by ground: 11 were DOA, eight died in the ED, and 21 died as inpatients. The index cases included 89 people with "killed" or "serious" police injury ratings at the scene. Eliminating the 13 people who died at the scene leaves 76 people with serious injuries who did not. Of that group, 18 (24%) were transported by helicopter. The universe of people involved or injured in nonfatal MVCs is not included in the study sample; therefore, death rates can not be calculated. However, the individual DOAs and ED and inpatient deaths can be reviewed by an appropriate panel to study EMS response, medical treatment, and outcome. Linking the inpatient hospital case mix data has been completed to determine additional details, such as injury severity, procedures, hospital charges, and disposition (home, rehabilitation hospital, long-term care, etc.). An effort was made to profile the injury severity for any person who was hospitalized as an inpatient subsequent to a fatal crash, whether or not he or she was recorded as being transported directly from the scene. These results will be reported in a subsequent article. Utilization Insights Resulting from the Index Event Linkage Review of the linked crash data provided examples of a variety of situations in which air medical services were not used at the scene but: • A mechanism of injury existed that was consistent with the current triage guidelines. • Multiple serious casualties were involved. • A helicopter was requested for the scene, but the mission was aborted or canceled. Also identified were situations in which air medical services were used at
L o c a t i o n of D e a t h by T r a n s p o r t S t a t u s Air medical transport-yes
Air medical transport-no
Total
0 2 2 5 9
13 11 8 21 53
13 13 10 26 62
the scene or later for inteffacility transfers but: • Multiple casualties were involved and multiple air medical transports were requested, but not all patients were transported by air. • Coordination was required between both air medical services to meet the needs of multiple people injured at the same crash. The average number of seriously injured people was greater than two, yet the helicopters generally were configured to transport one patient. • Scene pickups were canceled by the requester and reinstated later for inteffacility transfers. Conclusions about the appropriateness of EMS response and air medical transport cannot be drawn from the linkage data presented in this article alone. A peer review process would be necessary to provide in-depth review of the deployment of EMS and air medical resources to these crashes. Implications for the Impact of New Technology on the EMS System New technology in automotive design has led to the development of systems to capture or record, through onboard computers, the characteristics of a crash event. Some crash characteristics that may be associated with risk of serious injury are air bag deployment, "crash pulse," delta V (change in velocity), and rollover. The technology currently exists in certain m a k e / m o d e l vehicles to record this important information through event data recorders. In addition, some vehicles have the capability to transmit some information about a crash event to a call or help center generally operated by an automobile manufacturer. These call centers can then relay basic information about crash events to state 9-1-1 or EMS systems. General Motors' On-Star system is an example of an automatic crash notification (ACN) system; it has been designed to recognize a crash event that results in air bag deployment. Deployment then opens a line of communication between the vehicle occupants and the call center by which the center can talk with the occupants to determine if they need assistance. In a situation in which the occupants cannot communicate (eg,
July-September 2000
19:3 Air Medical Journal
unconscious), the call center refers informarion about the crash (eg, the car location) to a state 9-1-1 or EMS system. ACN is a subset of telematics, which refers to the c o n s u m e r products, services, and supporting systems that deliver information, communications, and entertainment to vehicles and mobile devices. The study suggests that a ~ t u r e ACN s y s t e m could be u s e d to c a p t u r e and transmit critical crash, vehicle, and perhaps o c c u p a n t characteristics to state EMS systems. With the use of appropriate guidelines, the EMS systems potentially could triage the crashes by optimal level of response needed: air medical, ALS, or BLS. This prioritization could save valuable response time and potentially better match the level of resources needed to the s e v e r i t y of c r a s h injuries that oc-
curred. The ultimate goal is to save lives and reduce disabilities from crashes. However, this type of ACN s y s t e m might be expected to deploy air medical or ALS services to 100% of the types of c r a s h e s p r e s e n t e d in t h i s a r t i c l e - - a trend that may present significant operational challenges to state EMS air medical systems and require different guidel i n e s and l e v e l s of r e s o u r c e s t h a n currently are used. Fatal crashes are just the "tip of the iceberg," however. F o r every fatal crash, several serious crashes occur, approximately eight to 10, that would place their own demands on air medical and EMS systems. Conclusion This article describes an index event
approach to air medical utilization re-
v i e w u s i n g data linkage. Fatal M V C s were used as the index events for this article. The approach identifies an entire population based on an aspect of the air m e d i c a l t r i a g e c r i t e r i a g u i d e l i n e and then collects detailed information available on that group through data linkage. Results were shown for all fatal MVCs from one of Massachusetts' five EMS regions for 1996. As a result of the regional findings, t h e M a s s a c h u s e t t s G o v e r n o r ' s Highway safety B u r e a u has funded an exp a n s i o n of t h i s s t u d y to c o l l e c t s t a t e w i d e l i n k e d d a t a for 1996 fatal MVCs. T h e B u r e a u of Health Quality and M a n a g e m e n t will collaborate with t h e G H S B on t h i s i n i t i a t i v e . T h e statewide results are expected to be reported later in 2000.
References
1. Bureau of the Census. Vital statistics of the United States, 1995. Washington (DC): Government Printing Offices;1995. 2. Massachusetts Department of Public Health, Bureau of Health QualityManagement & Office of Emergency Medical Services. Air medical services database. 1996. 3. Vermont Health PolicyCounciland Health Care Authority regulatory rulings regarding air medical transport within Vermont. 1996 Feb 27, April5. 4. American College of Surgeons Committee on Trauma. Resources for optimal care of the injured patient, 1999. Chicago:The College;1998. 5. Johnson S, Walker J. The crash outcome data evaluation system. NHTSA Technical Report. DOT HS 808 338. Washington (DC): National HighwayTrafficSafetyAdministration; 1996Jan.
6. Department of Transportation, National Highway Traffic SafetyAdministration. Fatal analysis reporting system, 1996. 7. Massachusetts Department of Public Health, Registry of Vital Records and Statistics. Death files. 1996. 8. Mango N, Garthe E. Why people die in motor vehicle crashes: linking detailed causes of death with FARSData. SAE Congress, 1998Feb. 9. Massachusetts Registry of Motor Vehicles. Police and operator crash report data. 1996. 10. Massachusetts Divisionof Health Care Finance and Policy. Hospital case mix and charge database, 1996. 11. Garthe E. The compatibilitybetween the abbreviated injury scale (AIS-80)and the international classification of diseases (ICD-9-CM).Proceedings from the annual conference of the Ameri-
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can Association of Automotive Medicine, San Francisco, California;1981. Quarterly Journal of the AAAM;March 1982. 12. MacKenzie EJ, Steinwachs MD, Shankar B. Classifying trauma severity based on hospital discharge diagnoses: validation of an ICD-9-CM to AIS-85 conversion table. Medical Care 1989;27:412. 13. Garthe E, Mango N. A motor vehicle crash injury specific map--ICD-9-CM to NASS/CDS. Proceedings of the AA.AMAnnual Conference, Orlando, Fla., 1997. 14. Baker SP, O'NeillB, Haddon W Jr, et al. The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma 1974;14:187-96.
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