a b s t r a c t

Background: Emergency medical services (EMS) preparedness is essential to reduce morbidity and mortality from mass casualty incidents .

Objectives: We sought to describe types and frequencies of common procedures performed during MCIs by EMS providers at different service levels.

Methods: This study was carried out using the 2012 US National EMS Public-Release Research Dataset maintained by the National Emergency Medical Services Information System. Emergency medical services activations coded as MCI at dispatch or by EMS personnel were included. The Center for Medicare and Medicaid Services service level was used for the level of service provided. A descriptive analysis characterizing the most common procedure types and frequencies by service level was carried out.

Results: Among the 19 831 189 EMS activations in the 2012 national data set, 53 334 activations had an MCI code, of which 26110 activations were included. There were 8179 advanced life support (31.3%), 5811 basic life support (22.3%), 399 air medical transport (air transport fixed or rotary) (1.5%), and 38 specialty care transport (0.2%) activations. A total of 107 different procedure types were reported. The most common procedures by procedure count were “spine immobilization” (21.8%) followed by “venous access extremity” (14.1%) and “assessment adult” (13.4%). A similar order was found for procedure frequencies by included EMS activations (24.1%, 19.3%, and 18.3%, respectively). Top 20 procedures had different frequencies by Levels of care except for “medical director control” (P = .19).

Conclusions: Advanced EMS interventions are not frequent during MCIs in the United States. emergency medical services systems with other types of providers or MCI response patterns might report different findings.

(C) 2015

Introduction

Mass casualty incidents (MCIs) can overwhelm emergency medical services (EMS) systems. Although historically considered infrequent, MCIs are increasing in frequency with a reported estimate of 36529 MCI EMS responses (95% confidence interval, 35431-37626) in the United States for the year 2010 [1]. The surge capacity of an EMS system to respond to MCIs is highly dependent on planning using the best

? Source(s) of support: This publication was supported by Cooperative Agreement Number DTNH22-09-H-00262 from the US Department of Transportation, National High- way Traffic Safety Administration. The findings and conclusions of this publication do not necessarily represent the official views of US Department of Transportation, National High- way Traffic Safety Administration.

?? Conflicts of interest: The authors report no conflicts of interest. The authors alone are

responsible for the content and writing of the paper.

* Corresponding author at: Department of Emergency Medicine, American University of Beirut Medical Center, PO Box 11-0236 Riad El Solh, Beirut 1107 2020, Lebanon. Tel.: +961 1 350000×6631.

E-mail address: [email protected] (M. El Sayed).

available evidence. However, most of the published literature involving MCIs consists of specific event descriptions or brief reports recounting anecdotal information. Lessons learned from different MCIs frequently cite challenges in command structure, coordination, and communication and emphasize the need for resource coordination, preplanning, quick triage, assignment of transport priorities, and limited on-scene interven- tions with appropriate casualty distribution to receiving facilities [2-4].

On scene, medical interventions usually consist of lifesaving inter- ventions, part of a triage system for mass casualties. SALT triage system (sort, assess, lifesaving interventions, treatment/transport) that was proposed by the Centers for Disease Control and Prevention as a national guideline for mass casualty triage lists the following interventions as lifesaving: controlling major hemorrhage, opening the airway, chest de- compression, and autoinjector antidote administration [5].

Over time, different procedures, such as prehospital tourniquet use for life-threatening Hemorrhage control, are advocated (or discouraged) for victims with critical injuries or illnesses during an MCI [6,7]. Limited data are available on the types and frequencies of procedures done by EMS providers in the prehospital setting for MCI patients in general.

http://dx.doi.org/10.1016/j.ajem.2015.04.035

0735-6757/(C) 2015

M. El Sayed et al. / American Journal of Emergency Medicine 33 (2015) 1030-1036 1031

Quantifying the current practice in MCIs and identifying if this practice varies by EMS service level can be very helpful for preparing and training EMS providers for procedures that would be required in MCIs.

The National Emergency Medical Services Information System (NEMSIS) maintains a US national EMS database, which, for 2012, includes EMS activations submitted by EMS agencies in 42 states and territories [1,8,9]. This repository allows us to examine MCIs at a national level, to evaluate trends in the prehospital management of MCI patients, and to estimate resource requirements at a local level in the event of an MCI. In this study, we used the NEMSIS 2012 data set to describe the types and frequencies of procedures or medical interventions done during MCIs by different levels of EMS providers. The goal of this project is to provide EMS agencies at all service levels with information regarding procedure use for better planning and estimation of resource require- ments for field management of MCI victims.

Methods

Study design

This retrospective cross-sectional study used the NEMSIS 2012 public research data set released by the NEMSIS technical assistance Center. Institutional review board exemption for use of this deidentified data set was obtained from the institutional review board of the American University of Beirut.

Study setting

The NEMSIS Technical Assistance Center maintains a national EMS database that collects 83 variables using standardized definitions and formats from US states and territories [9]. Data are collected locally by different EMS agencies and aggregated at the state level and submitted to the NEMSIS national database. Submissions from different states vary in terms of inclusion criteria and proportion of EMS activations submit- ted [1]. The NEMSIS is considered a convenience sample, on a national scale, for EMS activations in the United States [9]. A single patient acti- vating the EMS system might be represented in the national database more than once, due to multiple EMS vehicles responding to the patient care event and reporting to the state database. Thus, the term EMS activation represents a patient encounter by a single responding vehicle. The unit of analysis in this study was “EMS activation” rather than individual patients because the national EMS database provides a deidentified database structure, prohibiting analysis at a patient level. Each activation was, therefore, treated as an independent entry.

Study population

The 2012 NEMSIS national data set contains information on 19 831189 EMS activations [9]. We included EMS activations that were recorded as MCI either at dispatch (the complaint dispatch reported to the responding unit) or on scene by the EMS provider.

Available data

The primary objective of this study was to describe types and fre- quencies of procedures performed by different levels of EMS providers during MCIs. Standardized definitions in the NEMSIS manual were used. An MCI is defined as “an event which generates more patients at one time than locally available resources can manage using routine pro- cedures or resulting in a number of victims large enough to disrupt the normal course of emergency and health care services and would require additional non-routine assistance” [1,10]. A procedure is an intervention performed on a patient and that is part of the “list of procedures that the agency has implemented and is available for use.” Procedures are coded and reported in a standardized manner. The number of procedure attempts is also reported. For level of care of providers, we used the

Center for Medicare and Medicaid Services (CMS) service level for the EMS encounter and divided the levels into 5 categories: unknown, basic life support (BLS [BLS and BLS emergency]), advanced life support (ALS [ALS level 1, level 1 emergency, and level 2]), air medical transport including both fixed wing (airplane) and rotary wing (helicop- ter), and Specialty Care Transport . Additional variables that were analyzed to better characterize the study population included the fol- lowing: urbanicity (population setting using US Department of Agricul- ture and Office of Management and Budget definitions) [1], primary role of the responding unit, patient’s sex, incident location type, and if there was a possible injury and its cause.

Data analysis

The SAS version 9.1 (SAS, Cary, NC) was used for the management and analyses of the data. Nonparametric techniques (ie, ?² tests) were conducted to evaluate differences in procedure use by EMS level of service. Categorical variables were summarized using frequencies and percentages.

We initially conducted an overall count of all procedures done for all MCI-related activations and calculated frequencies by types and count. We then carried out a descriptive characterization of the study popula- tion followed by an analysis of the types of procedures and correspond- ing frequencies performed by different EMS service levels. We relied on 2 different denominators (total procedures count and total MCI activa- tions) to report percentages. Procedure frequency is the count of a spe- cific procedure divided by the total count of all reported procedures. For example, if the total count of all procedures is 10 and the count of a spe- cific procedure is 2 regardless of whether the same activation or differ- ent activations (ie, a procedure could be repeated), then that procedure frequency is 20%. Procedure frequency per activation is the percentage of EMS activations for which a procedure was reported divided by total number of activations. For example, if 10 activations were available and activation 1 had the same procedure done once or twice, then that procedure frequency per activation is 10%. Neither measure takes into account multiple attempts to complete a procedure.

We also assessed whether the reported procedure frequencies by different service levels varied by urbanicity. For these analyses, we grouped AMT and SCT service level categories to account for low fre- quency distributions. Homogeneity across strata of urbanicity was assessed through the likelihood ratio test (?² test). Statistical signifi- cance level was set at P b .05.

Results

A total of 53 334 EMS activations were recorded as an MCI. We excluded MCI-related activations recorded as “call cancelled,” “no patient found,” or “patient refused treatment.” The 26110 remaining MCI activations were included and analyzed. More than half of the acti- vations (63.1%) were in an urban setting. The primary role of the EMS unit reporting the activation was transport (91.0%). Injury was reported in 14481 activations (55.5%) with unknown cause of injury accounting for 53.7% of activations followed by motor vehicle traffic accidents (33.5%). The 5 categories of EMS level of care were identified with “unreported” accounting for a large portion of the activations (44.7%; Table 1).

Procedure frequencies

A total of 107 different procedure types were reported during MCIs with 41798 procedures reported for all MCI activations (Table 2). The 10 most frequently attempted procedures in descending order were as follows: “spine immobilization” (21.8%), “venous access extremity” (14.1%), “assessment adult”(13.4%), “pulse oximetry” (11.5%), “cardiac monitor” (7.5%), “Pain measurement” (6.3%), “blood glucose analysis” (3.6%), “wound care-general” (2.4%), “patient loaded” (2.0%), and “assessment pediatric” (1.6%). Among all reported procedures, 43

1032 M. El Sayed et al. / American Journal of Emergency Medicine 33 (2015) 1030-1036

Table 1

Mass casualty incident activations study population characteristics

Characteristic	Subcategory	Count, n (%)
MCI coding (n = 26110)	Complaint by dispatch	5513 (21.1%)
	Complaint by provider	19819 (75.9%)
Urbanicity (n = 25849)	Complaint by both Urban	778 (3%) 16297 (63%)
	Rural	5065 (19.6%)
	Suburban	2929 (11.3%)
Primary role of the unit (n = 26110)	Wilderness Transport	1558 (6%) 23769 (91%)
	Nontransport	1764 (6.8%)
	Rescue	472 (1.8%)
Sex (n = 26110)	Supervisor Male	105 (0.4%) 11656 (44.6%)
	Female	12212 (46.8%)
CMS service level (n = 26110)	Not reported	2242 (8.6%)
	Not reported	11683 (44.7%)
	ALS	8159 (31.2%)
	BLS	5811 (22.3%)
	AMT	399 (1.5%)
Incident location type (n = 26110)	SCT Street or highway	38 (.2%) 14036 (53.7%)
	Home/residence	5158 (19.7%)
	Health care facility (clinic, hospital, or nursing home)	1573 (6%)
	Not reported	1215 (4.6%)
	Public building (schools, government offices)	1080 (4.1%)
	Place of recreation or sport	777 (2.9%)
	Other location	733 (2.8%)
	Trade or service (business, bars, restaurants, etc)	671 (2.6%)
	Industrial place and premises	228 (0.9%)
	Residential institution (nursing home, jail/prison)	432 (1.6%)
	Lake, river, ocean	120 (0.5%)
Possible injury (n = 26110)	Farm Mine/quarry Yes	82 (0.3%) 5 (b0.1%) 14481 (55.5%)
	No	7437 (28.5%)
	Not reported	4192 (16%)
Cause of injury (n = 26110)	Not reported	14013 (53.7%)
	Motor vehicle traffic accident	8746 (33.5%)
	Motor vehicle nontraffic accident	825 (3.2%)
	Struck by blunt/thrown object	603 (2.3%)
	Falls	584 (2.2%)
	Motorcycle accident	415 (1.6%)
	Fire and flames	113 (0.4%)
	Pedestrian traffic accident	127 (0.5%)
	Firearm assault	104 (0.4%)
	Chemical poisoning	84 (0.3%)
	Smoke inhalation	52 (0.2%)
	Stabbing/cutting assault	56 (0.2%)
	Water transport accident	47 (0.2%)

types were infrequently reported (ie, count b 10) including “decontam- ination” and “wound care-tourniquet”.

Procedure frequencies per activations

Overall, less than a quarter of MCI-related EMS activations reported a procedure with spine immobilization being the most frequently re- ported (24.1%). Among the top 20 procedures reported for all provider levels (Table 3), less than half required additional equipment beyond general assessment and transport of patients. These included “venous access” (extremity) and “venous access Blood draw,” “cardiac monitor- ing,” “blood glucose analysis,” “wound care” (general), “12-lead ECG,” and “airway nasal.” airway interventions were not frequent with “air- way nasal” and “airway bagged BVM” occurring in 1.3% and 0.8% of

cases, respectively. Tourniquet application was very rare and was re- ported in only 7 EMS activations. chest decompression was reported in 40 EMS activations.

Procedures performed during MCIs by different levels of care

Spine immobilization was the most frequently reported procedure performed for MCI patients at the BLS level (16.2%; Table 4). Medical control during MCI was not frequently reported, only 1.8% among BLS activations.

Procedures were more frequently performed among ALS level providers with “venous access extremity” occurring among 32.2% of ALS activations. Spine immobilization was the second most commonly performed procedure among ALS providers (28.4%).

M. El Sayed et al. / American Journal of Emergency Medicine 33 (2015) 1030-1036 1033

Table 2

Procedure frequencies

Top procedure type	Count (n = 41798)	Frequency (%)		Top procedure type	Count (n = 26110)	Frequency (%)
Spine immobilization	9101	21.80		Spine immobilization	6306	24.1
Venous access, extremity	5876	14.10		Venous access, extremity	5047	19.3
Assessment, adult	5609	13.40		Assessment, adult	4770	18.3
Pulse oximetry	4799	11.50		Pulse oximetry	3489	13.4
Cardiac monitor	3127	7.50		Cardiac monitor	3038	11.6
Pain measurement	2651	6.30		Pain measurement	1863	7.1
Blood glucose analysis	1488	3.60		Blood glucose analysis	1459	5.6
Wound care, general	1026	2.40		Wound care, general	936	3.6
Patient, loaded	830	2.00		Patient, loaded	767	2.9
Assessment, pediatric	676	1.60		Assessment, pediatric	620	2.4
12-lead ECG, obtain	661	1.60		12-lead ECG, obtain	588	2.2
Splinting, basic	616	1.50		Splinting, basic	577	2.2
Temperature measurement	603	1.40		Temperature measurement	485	1.9
Contact medical control	455	1.10		Contact medical control	437	1.7
Venous access, blood draw	401	1.00		Venous access, blood draw	353	1.3
Extrication	357	0.80		Airway, nasal	348	1.3
Airway, nasal	352	0.80		Extrication	325	1.2
Patient, off-loaded	290	0.70		Patient, off-loaded	268	1
Airway, bagged (via BVM)	212	0.50		Airway, bagged (via BVM)	205	0.8
Capnography (CO2 measurement)	200	0.50		Orthostatic blood pressure management	185	0.7
Other procedures	2468	5.90

Table 3

Procedure frequencies per activations (all levels)

Abbreviation: BVM, bag valve mask.

Pulse oximetry was the most frequent procedure reported among MCI activations transported by air (48.6%). Airway interventions were also more frequently performed among AMT providers.

The number of activations billed at the SCT level was low (38). “Air- way ventilator operation” was among the top 10 procedures performed among SCT activations (13.2%). Similar to AMT level, airway-related procedures were more frequently reported.

When comparing the frequency of Procedure performance between the different levels of EMS care, a statistically significant difference was found for all procedures reported among the “top 20” across different levels of care (P b .05) except for “contact medical control” (P = .19; Figure).

The associations between reported procedure frequencies and EMS service level were found to be significant according to urbanicity (P b

.05) for almost all top 20 most frequently reported procedures except

for “splinting basic,” “airway nasal,” and “airway bagged (via BVM)” (data not shown).

Discussion

This is the first study to date that uses a national data set to examine management patterns and frequencies of procedures performed among MCI-related activations.

The study has important implications regarding MCI preparedness for EMS systems. Emergency medical services agencies at all service levels can use these data to plan resource requirements and to train and prepare EMS providers for MCIs. By examining procedure frequen- cies or how often procedures are performed, EMS administrators can plan for equipment requirements related to interventions in the event of an MCI. Similarly, EMS medical directors can use procedure frequen- cies per activations or how often procedures are performed per activa- tions, to become familiar with the types and frequencies of procedures that are done during MCIs to improve training and medical protocols to better prepare EMS providers for commonly performed interventions.

In the NEMSIS 2012 data set, procedures reported by EMS providers responding to MCIs are not frequent and fall within the expected Scope of practice of providers at each specific level of training. The most com- mon procedures reported across all EMS level of care consist mainly of BLS procedures. The rate of spine immobilization during MCIs (24.2%) is similar to that previously reported by the Dutch ambulance services in a Turkish airlines crash near Amsterdam in 2009 [11]. During that crash, 75 of 100 patients transported by EMS to receiving hospitals did not receive any form of immobilization [11]. The Dutch system used

the TriAge SIeve and Sort Algorithm for triage, the guidelines for field tri- age devised by the American College of Surgeons and Nexus criteria for spine immobilization [12-14]. A higher immobilization rate was de- scribed in a case review of an MCI in the United States involving 35 pa- tients (full-size tour bus accident) where approximately 48.6% (17/35) of patients received prehospital immobilization. This was, however, a descriptive review more focused on operations and scene management of MCIs and less on Prehospital interventions [15].

More procedures were reported for ALS level activations. This re- flects the fact that ALS providers have a larger skill set and a wider scope of practice than BLS providers. The most frequent ALS procedure reported was venous access. This finding was expected because billing at the ALS level by CMS requires the provision of ALS procedures that in- clude, but are not limited to, intravenous access for medication admin- istration. More specifically, billing at ALS level 2 usually requires “at least three separate administrations of one or more medications by in- travenous push/bolus or by continuous infusion (excluding crystalloid fluids)” or provision of at least one of the following ALS level 2 proce- dures listed: manual defibrillation/cardioversion, endotracheal intuba- tion, Central venous line, cardiac pacing, chest decompression, Surgical airway, or intraosseous line [16]. Most other procedures reported at the ALS level with the exception of Peripheral venous access, cardiac monitoring, and obtaining 12-lead electrocardiogram consisted of BLS level procedures.

Similar findings were noted at the AMT level with more frequent airway-related interventions. Procedures at the SCT level, although uncommon, were more advanced and consisted mainly of airway and Ventilator management in addition to cardiac monitoring. This finding is consistent with the fact that SCT teams are involved at a later stage of the MCI and mainly conduct interfacility transports rather than immediate MCI scene response [16].

A primary objective during an EMS response to MCIs in the United States relates to ensuring agencies and responders integrate within the Incident Command System for scene management and emphasize using a triage system such as SALT or START triage to assign transport priorities. The recommended procedures to be used on scene consist of lifesaving interventions only. The findings of our study reflect this practice with the low rate of reported procedures during MCIs.

The finding of significant associations between reported procedure frequencies and EMS service levels according to urbanicity is also expected because the prehospital phase and on-scene times are usually longer in rural and wilderness settings compared to urban ones. More prehospital management is also needed in such cases until arrival to definitive destination. This finding may also be related to the different

1034

Table 4

Twenty most frequent procedures by EMS level of care

M. El Sayed et al. / American Journal of Emergency Medicine 33 (2015) 1030-1036

	Unknown, n = 11683			BLS, n = 5811			ALS, n = 8159			AMT, n = 399			SCT, n = 38
	Procedure type	n (%)		Procedure type	n (%)		Procedure type	n (%)		Procedure type	n (%)		Procedure type	n (%)
	Spine immobilization	2994 (25.6)		Spine immobilization	941 (16.2)		Venous,	2637 (32.2)		Pulse oximetry	194 (48.6)		Pulse oximetry	9 (23.7)
							access extremity
	Assessment, adult	2379 (20.4)		Assessment, adult	818 (14.1)		spinal immobilization	2323 (28.4)		Pain measurement	169 (42.4)		Cardiac monitor	9 (23.7)
	Venous access, extremity	2210 (18.9)		Pulse oximetry	567 (9.7)		Cardiac monitor	1584 (19.4)		Assessment, adult	167 (41.8)		Venous access, extremity	6 (15.8)
	Pulse oximetry	1568 (13.4)		Pain measurement	262 (4.5)		Assessment, adult	1403 (17.2)		Blood glucose analysis	71 (17.8)		Airway, ventilator operation	5 (13.2)
	Cardiac monitor	1358 (11.6)		Blood glucose analysis	164 (2.8)		Pulse oximetry	1151 (14.1)		Venous access, extremity	60 (15.0)		Assessment, adult	3 (7.9)
	Pain measurement	795 (6.8)		Patient, loaded	139 (2.4)		Pain measurement	636 (7.8)		Spine immobilization	47 (11.9)		Orthostatic BP measurement	2 (5.3)
	Blood glucose analysis	635 (5.4)		Venous access, extremity	134 (2.3)		Blood glucose analysis	589 (7.2)		Temperature measurement	45 (11.3)		Capnography	2 (5.3)
	Wound care, general	531 (4.6)		Wound care, general	120 (2.1)		12-lead ECG, obtain	419 (5.1)		Extrication	37 (9.3)		(CO2 measurement) Venous access, existing catheter	2 (5.3)
	Assessment, pediatric	376 (3.2)		Assessment, pediatric	105 (1.8)		Wound care, general	276 (3.4)		Assessment, pediatric	33 (8.3)		Airway, bagged (via tube)	2 (5.3)
	Patient, loaded	368 (3.2)		Contact medical control	104 (1.8)		Temperature measurement	271 (3.3)		Patient, loaded	31 (7.8)		Spine immobilization	1 (2.6)
	Splinting, basic	312 (2.7)		Splinting, basic	77 (1.3)		Airway, nasal	240 (2.9)		Cardiac monitor	26 (6.5)		Pain measurement	1 (2.6)
	Contact medical control	188 (2.6)		Orthostatic BP measurement	72 (1.2)		Venous access, blood draw	234 (2.9)		Airway, intubation confirm EB	18 (4.5)		Wound care, general	1 (2.6)
	12-lead ECG, obtain	155 (1.3)		Patient, off-loaded	63 (1.1)		Patient, loaded	229 (2.8)		Airway, nasal	17 (4.3)		Contact medical control	1 (2.6)
	Extrication	163 (1.4)		Cardiac monitor	61 (1.0)		Splinting, basic	184 (2.2)		Airway, orotracheal intubation	12 (3.0)		Temperature measurement	1 (2.6)
	Temperature measurement	117 (1.0)		Temperature measurement	51 (0.9)		Contact medical control	143 (1.7)		Specialty center activation,	9 (2.3)		Airway, bagged (via BVM)	1 (2.6)
										adult trauma
	Venous access, blood draw	110 (0.9)		Airway, nasal	37 (0.6)		Patient, off-loaded	116 (1.4)		Capnography (CO2 measurement)	9 (2.3)		Airway, orotracheal intubation	1 (2.6)
	Airway, bagged (via BVM)	108 (0.9)		Airway-cleared, opened, or Heimlich	28 (0.5)		Assessment, pediatric	106 (1.3)		Wound care, general	8 (2.0)		Airway, suctioning	1 (2.6)
	Patient off-loaded	88 (0.8)		Airway, bagged (via BVM)	24 (0.4)		Extrication	106 (1.3)		Airway, rapid sequence intubation	8 (2.0)		Airway, nebulizer treatment	1 (2.6)
	Airway, orotracheal intubation	74 (0.6)		Extrication	19 (0.3)		Capnography	86 (1.1)		Airway, ventilator operation	7 (1.7)		Airway, intubation confirm	1 (2.6)
	Venous access,	70 (0.6)		Patient cooling (cold pack, etc)	19 (0.3)		(CO2 measurement) Airway, bagged (via BVM)	71 (0.9)		Chest decompression	7 (1.7)		colorimetric ETCO2 Splinting, traction	1 (2.6)

existing catheter

Abbreviations: BP, blood pressure; EB, esophageal bulb.

M. El Sayed et al. / American Journal of Emergency Medicine 33 (2015) 1030-1036 1035

Figure. Comparison of frequencies across different levels in the top 20 procedures.

types of MCIs occurring in different settings. This was not, however, assessed in our study.

The findings of this study can help EMS systems plan for MCI responses. Our findings, however, are closely linked to the structural elements of EMS systems in the United States: in terms of prehospital provider levels, MCI response training, scope of practice, and the existing MCI response framework. Despite the fact that EMS systems in the United States are highly advanced and developed, there seems to be a limited role for advanced interventions in MCI activations. Other systems with different types of providers (such as physicians) and with different MCI response patterns may report different frequen- cies of field procedures. Countries with less developed EMS systems can plan a basic level response to MCIs without the worry of advanced resource requirements in the field.

Limitations

Our study used data from a national database that may be subject to information and selection bias because inconsistencies in the measure- ment and reporting of clinical variables, treatment options, and trans- port practices may systematically differ between reporting agencies. In addition, missing data were not excluded from our study and were re- ported as a separate category to allow for comparison. Although it is likely that not all procedures were documented in the national data- base, there is little reason to believe that ALS vs BLS procedures are more or less likely to be documented. Thus, the differences in ratios (or percentages) that we report between the prevalence of basic and advanced procedures is likely not overtly influenced by systematic bias. Finally, we should note that NEMSIS data represent EMS resource activations and not the number of treated patients. For the purposes of this study, this fact allowed us to focus on actual procedure frequency, types, and utilization patterns across multiple providers who may have cared for the same MCI patient over the course of an actual incident.

Conclusion

Procedures performed by EMS providers during MCIs are infrequent. Although ALS level activations had higher rates of procedures performed, BLS-type procedures were most common. These findings

may be related to billing systEMS used by EMS and to the type of MCI re- sponse training that EMS providers receive in the United States. Emergency medical services systems can, however, use the findings of this study to plan and manage resources needed for MCI activations.

Acknowledgment

The authors would like to acknowledge and thank all of the partici- pating EMS providers, EMS agencies, and state EMS offices who support and provide data to the NEMSIS national database.

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