EMS
A New Approach to Teaching Prehospital Trauma Care to Paramedic Students From the Department of Emergency Medicine, New Mexico Emergency Medical Services Academy, University of New Mexico, School of Medicine, Albuquerque, NM.
David R Johnson, MD Darryl Macias, MD Ann Dunlap, PhD, NREMT-P Mark Hauswald, MD David Doezema, MD
Received for publication September 23, 1996. Revisions received January 6 and July 28, 1998. Accepted for publication August 12, 1998. Presented at the Annual Meeting of the National Association of EMS Physicians 1994, Portland, OR. Address for reprints: Darryl J Macias, MD, University of New Mexico Hospital, Department of Emergency Medicine, 4th Floor ACC, Albuquerque, NM 87131; 505-272-5062, fax 505-272-6503, E-mail
[email protected]. Copyright © 1999 by the American College of Emergency Physicians. 0196-0644/99/$8.00 + 0 47/1/94995
Study objective: A modification of the standard Department of Transportation student paramedic curriculum encouraging individualized patient assessment decreases inappropriate on-scene procedures (OSPs) and scene time, measured on simulated patients. Methods: Scenario-based testing from 1991 through 1993 was videotaped for all students. A new trauma curriculum was introduced in 1992, individualizing patient assessment and prioritization of OSPs. Recorded OSPs included spinal immobilization, application of military antishock trousers, endotracheal intubation, cricothyrotomy, intravenous catheter insertion, and needle thoracostomy. Twenty videotaped random student performances of the 1991 class was compared with a similar sample of 20 from the 1993 class; scene times and the OSP numbers were measured. Two board-certified independent emergency physicians unfamiliar with the students or the new curriculum reviewed all 40 tests on a master videotape. Patient assessment appropriateness, scene time, OSPs, scenario difficulty, and number of inappropriate OSPs were evaluated using a linear analog scale. Data are presented as means with confidence intervals (CIs), analyzed by Student’s t test and the Mann-Whitney 2-sample test. Results: Scene time from 1991 to 1993 decreased overall with a mean of 4.3 minutes (95% CI 2.8 to 5.8 minutes), as did the number of OSPs: 3.1 versus 1.7 (mean difference, 1.45 OSPs per scenario; 95% CI .91 to 1.99). Physician reviewers noted improvements in the appropriateness of patient assessment, scene time, and OSPs from 1991 to 1993. There was no significant difference in scenario difficulty for 1991 compared with 1993. Inappropriate OSPs done on scene declined. Physician 1 indicated a mean of inappropriate procedures of 1.6 in 1991 versus .5 in 1993. Physician 2 indicated a mean of 1.4 in 1991 versus .3 in 1993. Conclusion: This new paramedic curriculum decreased onscene time and inappropriate use of procedures in stabilizing the condition of patients with simulated critical trauma.
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[Johnson DR, Macias D, Dunlap A, Hauswald M, Doezema D: A new approach to teaching prehospital trauma care to paramedic students. Ann Emerg Med January 1998;33:51-55.]
available personnel differs from treatment in an urban location. Other factors, such as mechanism of injury, personnel, patient access, and transport time influences decisionmaking, yet no published paramedic training curriculum exists that explicitly considers these aspects.
INTRODUCTION
Despite limited research into the efficacy of many prehospital procedures, little has changed with regard to paramedic trauma care curriculum, with minimal guidance given for on-scene prioritization of resource utilization and on-scene procedures (OSPs).1 Paramedics are generally taught to manage trauma patients in a strictly protocol-driven fashion,1 rather than accounting for individual circumstances. Although most interventions can be beneficial to selected trauma patients, delayed transport of others to a hospital where definitive care can be delivered may result in an adverse outcome.2,3 Specifically, much of the controversy has centered on the prehospital use of intravenous fluids and military antishock trousers (MAST). 4 Other largely unproven techniques such as spinal immobilization and chest decompression may not be appropriate in the management of individual cases. Similarly, different approaches are required for victims of blunt versus penetrating trauma. A single thoracic stab wound usually requires minimal field assessment compared with multiple injuries sustained in a motor vehicle crash. Furthermore, the “setting” in which the traumatic event occurs may dictate the degree of field stabilization needed in a given situation. The treatment of a patient in a rural setting with long transport times and a paucity of
M AT E R I A L S A N D M E T H O D S
The standard Department of Transportation (DOT) trauma curriculum was taught to all of our paramedic classes up to 1992; our modified curriculum taught at the New Mexico EMS Academy additionally focused on disease processes and prioritization of procedures appropriate for a given prehospital setting and patientpresentation. Issues such as mechanism and severity of injury, availability of personnel, transport times, and patient access were included as additional considerations individualizing patient assessment. Treatment algorithms were developed based on current prehospital emergency medicine research or existing literature5 to aid in decisionmaking. Before passing the trauma course, each student was required to assess and manage a simulated trauma patient, and to demonstrate proficiency in 2 of 3 randomly chosen performances at the end of the entire paramedic curriculum. The simulated patient scenarios were not the same, but did not significantly differ between classes, although students from the 1991 class were allowed unlimited numbers of assistants. The 1993 class, however, were given varying numbers of assistants. This forced the student to consider alternative resources when treating the simulated patient, comparable with a true field situation. Allotted time for
Table.
Student performance ratings by 2 EMS physicians. Performance Measure
Rater
1991 Class
1993 Class
Appropriateness of patient assessment
Physician 1
32 mm
62 mm
Appropriateness of scene time
Physician 2 Physician 1
30 mm 22 mm
68 mm 59 mm
Difficulty of scenario
Physician 2 Physician 1
21 mm 54 mm
66 mm 63 mm
Physician 2
48 mm
50 mm
κ (95% CI)
.70 (.54 to .86) .86 (.77 to .93) .26 (.01 to .51) 1991: .76 (.66 to .87) 1993: .88 (.82 to .93) Inappropriate procedures
Physician 1
1.6
.5
Physician 2
1.4
.3
.50 (.29 to .71)
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didactic material and laboratory practice in both classes was equivalent. The same instructors were used for the same classes and laboratory sessions for both years. Proficiency in performing individual procedures had been demonstrated earlier in the trauma course. Scenario testing for all students was recorded on videotape. Students were informed of this policy at the beginning of the course. Videotaping at that time was done in a random fashion. No paramedic did more than 1 scenario. In 1994, all videotapes were collected and reviewed for recording quality. A person unfamiliar with the study or any participants did this review. In a few cases, scenarios were necessarily excluded from use because of poor videotape quality (inability to hear orders, or to clearly see what procedures the student was performing). Scenarios were not, however, excluded on the basis of whether the individual student received a passing evaluation in the scenario. From the viewable scenarios, 20 randomly selected student performances from each class were copied onto a master tape. Performances were selected by rewinding the tape and selecting the first trauma assessment scenario encountered. The scenarios of the 2 classes were matched only with respect to mechanism of injury (blunt versus penetrating trauma). All 40 performances from the 2 classes were randomly copied to 1 master tape with scenarios preceded by a brief synopsis. Scene time was measured in seconds and was defined as beginning when the student first made physical contact with the patient and ending when the patient was moved to an ambulance gurney and the student verbalized initiation of transport. The number of OSPs was counted and included endotracheal intubation, cricothyrotomy and needle thoracostomy, insertion of intravenous catheters, spinal immobilization,and application of MAST. “Inappropriate” OSPs were defined as OSPs that were not indicated for a specific scenario (eg, cervical spine immobilization for a penetrating chest injury). Procedures that were relatively contraindicated for that scenario (eg, prolonged intravenous insertion attempts/MAST application on scene for a hemodynamically compromised patient who needs immediate transport to a trauma facility) were also deemed “inappropriate.” Two board-certified emergency physicians with extensive experience in EMS and EMS medical direction reviewed the master tape. Both assessors were blinded without previous contact with either class, or with the development of the new curriculum. For each of the student performances, the physicians recorded the number of inappropriate OSPs based on their impressions of reasonable medical care. The physicians did not use the algorithms, since the algorithms were developed for the class of 1993. The physicians rated each performance on 100-mm linear analog scales with
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regard to the appropriateness of patient assessment, scene time, and the difficulty of the scenario. All data are presented as means with 95% confidence intervals (CIs). Continuous variables were analyzed by Student’s t test. The Mann-Whitney 2-sample test was used where appropriate. Exact weighted κ values with 95% CI were also calculated. R E S U LT S
Twenty trauma simulations were reviewed in each of the 2 paramedic classes. In both groups 13 blunt trauma and 7 penetrating trauma scenarios were reviewed. The new curriculum resulted in a decrease in overall mean scene time of 4.3 minutes (95% CI 2.8 to 5.8 minutes). A subgroup analysis of the 2 classes demonstrated that for blunt trauma, the class of 1993 spent 2.3 minutes less on scene (95% CI .5 to 4.2). For penetrating trauma, the latter class spent an average of 7.9 minutes less on scene (95% CI 6.7 to 9.0). Although there was a trend toward shorter scene times for blunt trauma in the 1993 class, the overall decrease in scene times occurred primarily in the penetrating trauma scenarios. The Table shows results of the review by the 2 boardcertified emergency physicians. Ratings by the physicians on linear analog scales showed improvements in patient assessment and appropriateness of scene time. Interobserver agreement for appropriateness of scene time was excellent (κ=.86, 95% CI .77 to .93),6 whereas agreement for patient assessment was moderate (κ=.70, 95% CI .54 to .86).6 Although averages of scenario difficulty appeared somewhat equivalent, interobserver agreement for all 20 scenarios with respect to difficulty was poor (κ=.26, 95% CI .01 to .51).6 The number of inappropriate procedures done on scene declined. Physician 1 indicated a mean of inappropriate procedures of 1.6 in 1991 versus .5 in 1993. Physician 2 indicated a mean of 1.4 in 1991 versus .3 in 1993. The number of OSPs performed also decreased from 3.1 per scenario in 1991 to 1.7 in 1993 (mean difference, 1.45 OSPs per scenario; 95% CI .91 to 1.99). Interestingly, up to 20% of those deleted procedures between the classes may have been deemed “appropriate,” but were not specifically measured in the study. Serious omissions (not using spinal immobilization when indicated, for instance) would have resulted in failure; no student failed. For all 4 variables, agreement between the physicians was good in 1991 (κ=.76, 95% CI .66 to .87). Agreement between the physicians was excellent in 1993 (κ=.88, 95% CI .82 to .93). The observed difference in κ value by year was not statistically significant (P>.05).6
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DISCUSSION
The efficacy of the standard DOT curriculum has not been studied extensively, yet most paramedic curricula are based on this standard. The existing curriculum may insufficiently tailor assessment and treatment for individual circumstances, likely resulting in longer scene times. In our curriculum, students from the latter class demonstrated shorter scene times, less inappropriate procedures, and were encouraged to use “clinical judgment,” which is not commonly taught to paramedic students. For instance, we stressed that unless there is a necessary delay in transport, all intravenous lines are to be started en route to the hospital; previous field studies validate this.7 Selective spinal immobilization was also taught. Those with minor mechanisms of injury, no neck pain or tenderness, no neurologic complaints or findings, and no distracting injuries would not require cervical spine immobilization. Immobilization is mandated if these criteria are not met.8 Furthermore, spinal immobilization would be unnecessary in most cases of penetrating trauma, especially in the absence of neurologic signs or symptoms.9 Unnecessary spinal immobilization may be of limited benefit, and may delay transport where definitive care would better serve a patient, given that full immobilization can also take almost 3 minutes to accomplish under optimal conditions.9 Moreover, evidence supporting the efficacy of backboards in preventing further neurologic injury is lacking, and could actually be deleterious to the patient.9 However, pending further outcome data, overimmobilization may be prudent in uncertain circumstances. Students were taught to evaluate and treat trauma patients in consideration of available personnel and training level, patient access barriers, transport unit availability, and need for other resources such as extrication and fire suppression. These factors were weighted in a fashion akin to real field triage: immediate life-threatening injuries are dealt with on scene, with subsequent transport; injuries that would threaten survival at a later time would be treated en route. Students also learned resource management skills based on initial dispatch information before scene arrival. When videotaped performances from a class before the new curriculum were compared with those from after the new curriculum, there was a significant decrease in scene time. This was likely a result of the decrease in OSPs performed. On subgroup analysis, it appears that the major decrease in scene time was for simulated penetrating trauma cases. Gervin and Fischer2 suggested that there is a significant correlation between survival from penetrating trauma to the heart and scene time, thus scene time may be a surrogate marker for survival.
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This study had some significant limitations. Although scene time may be a logical surrogate of outcome 2 (“the faster to the hospital, the better”), it is not definitive. Further outcome studies are necessary to correlate scene times to outcome. Actual scenarios given to the students were not controlled for; although patient injuries were similar, environmental factors differed. Different scenarios given to the 2 groups might produce different results. The 2 physician reviewers did not find any significant difference in the difficulty of the scenarios between the 2 classes. Nonetheless, groups were not specifically assessed for motor skill competency—although the same instructors taught both classes, we did not account for how well 1 student in a given class could “outperform” another. It is also intuitive that students perform in the manner in which they are taught; although the reviewers had no previous knowledge of the curriculum, they may have favorably graded faster scenarios if they themselves approve of this philosophy. It is impossible to conclude that the measurements indicate improved quality; outcome studies in the field would be necessary to validate this. Nevertheless, previous EMS literature has not challenged paramedic teaching standards to this degree; evolution of existing standards therefore necessitate studies such as this to be improved on with validation from the field. We used linear analog scales to rate the student performances in a subjective basis. Although this methodology has been used in rating pain, less experience exists with this method to measure other subjective variables.10 Linear analog scales are powerful tools to demonstrate small statistical differences between interventions; the clinical significance of these differences, however, can easily be questioned.10 Although a well-defined measurable endpoint for scenario difficulty and appropriateness of OSPs was lacking, we used equivalent scenarios for each class. We did not specifically capture omissions, although necessary omissions would have resulted in failure, which did not occur. Physician reviewers did not receive specific instructions or protocols to compare assessments for appropriateness; they evaluated scenarios on the basis of their view of “reasonable treatment” expected of any paramedic. More reviewers, and the availability of a well-researched, standard nationwide EMS treatment protocol would have minimized these problems. In conclusion, the adoption of a new curriculum, which stresses the mechanism of injury, and the setting in which a traumatic event occurs, enables paramedics to individualize patient care. Such individualized care can result in a decrease in scene times and the number of procedures performed on the scene in simulated trauma scenarios. These effects can
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be shown to be appropriate when reviewed by experienced EMS physicians. The effect on patient outcomes will have to await carefully designed field studies. REFERENCES 1. Bledsoe BE, Porter RS, Shade BR: Paramedic Emergency Care, ed 3. Upper Saddle River, NJ: Brady Prentice Hall, 1994:553-569. 2. Gervin AS, Fischer RP: The importance of prompt transport in salvage of patients with penetrating heart wounds. J Trauma 1982;22:443-448. 3. Spaite DW, Tse DJ, Valenzuela TD, et al: The impact of injury severity and prehospital procedures on scene time in victims of major trauma. Ann Emerg Med 1991;20:1299-1305. 4. Mattox KL, Bickell W, Pepe PE, et al: Prospective MAST study in 911 patients. J Trauma 1989;29:1104-1112. 5. Rosen P, Barkin RM: Emergency Medicine; Concepts and Clinical Practice, ed 3. St. Louis: Mosby–Year Book, 1992. 6. Fleiss JL: Statistical methods for rates and proportions. Wiley Series in Probability and Mathematical Statistics, ed 2. New York: John Wiley & Sons, 1981:212, 236. 7. Slovis CM, Herr EW, Londorf D, et al: Success rates for initiation of intravenous therapy en route by prehospital care providers. Am J Emerg Med 1990;8:305-307. 8. Ringenberg BJ, Fisher AK, Vrandeta LF, et al: Rational ordering of cervial spine radiographs following trauma. Ann Emerg Med 1988;17:792-796. 9. Hauswald M, Ong G, Tandberg D, et al: Out of hospital spinal immobilization: Its effect on neurologic injury. Acad Emerg Med 1998;5:214-219. 10. Todd KH, Funk JP: The minimum clinically important difference in physician-assigned visual analog pain scores. Acad Emerg Med 1996;3:142-146.
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