Injury profiles in pedestrian motor vehicle trauma

~iiiii!i

ORIGINAL CONTRIBUTION motor vehicle accidents, pedestrians; trauma, motor vehicle, pedestrian

Injury Profiles in Pedestrian Motor Vehicle Trauma One hundred fifteen consecutive pedestrians who were struck by motor vehicles were studied to determine the magnitude and patterns of the injuries sustained. The mortality rate was 22%, and 17 of 25 patients who died did so during the initial resuscitative efforts, primarily due to head, chest, and/or abdominal injury. The average Injury Severity Score (ISS) among all patients was 20; however, it was significantly higher (46) in nonsurvivors. The majority of the victims were men (72%), and the average age of all patients was 35 years. As the patient's age increased, so did the likelihood of mortality, fractures, and prolonged hospital stay Blood alcohol levels were measured in 85 patients, 65% of whom had detectable levels (mean, 0.25 mg/dL). There was no correlation between the presence of alcohol and mortality, ISS, head injury, or number of fractures. The most frequently injured organ system was musculoskeletal (77%), followed by head (34%), abdomen (2I%), and chest (15%). The most common fractures seen were tibia-fibular (39), pelvis (35), and femur (31). Hospital stay averaged 11 days, and patient charges averaged $16,900. /Brainard BJ, Slauterbeck J, Benjamin JB, Hagaman RM, Higie S: Injury profiles in pedestrian motor vehicle trauma. Ann Emerg Med August 1989;18: 881-883.]

INTRODUCTION Motor vehicle and traffic accidents are the leading cause of premature death in the United States. Pedestrian motor vehicle accident victims comprise 14% of this groupJ Although they represent a small proportion of the overall number of traffic accident victims, these patients have the highest mortality and morbidity rates (greater than motor vehicle occupants or motorcyclists2,.~), especially in rural areas. Other than epidemiologic studies documenting the existence of this problem within the spectrum of motor vehicle trauma, little has been written characterizing this subset of patients. The purpose of our study was to investigate the injury patterns and health care requirements associated with pedestrians struck by motor vehicles.

Bradley J Brainard, MD James Slauterbeck, MD James B Benjamin, MD Roberta M Hagaman, MS Stephanie Higie, RN Tucson, Arizona From the Section of Orthopedic Surgery, University of Arizona Health Sciences Center, Tucson. Received for publication August 29, 1988. Revision received March 20, 1989. Accepted for publication April 4, t989. Presented at the 18th Annual Scientific Meeting of the Western Trauma Association, February, March, 1988, Steamboat Springs, Colorado. Address for reprints: James Benjamin, MD, Department of Surgery, Section of Orthopedics, University of Arizona Health Sciences Center, Tucson, Arizona 85724.

MATERIALS A N D METHODS The University of Arizona Health Sciences Center was established as a Level I trauma center in August 1985. The indications for primary transport to this center are respirations less than 10 or more than 29; systolic blood pressure less than 90 m m Hg; or Glasgow Coma Scale less than 13. All pedestrians struck by a motor vehicle believed to be traveling at Z0 mph or more are transported to a Level I facility. Pedestrians struck by slower moving vehicles are also taken to a Level I trauma center unless another facility is requested. The medical records of all pedestrian motor vehicle accident victims treated between August l, 1985, and June l, 1987, were reviewed for standard epidemiologic data, injury patterns, and hospital course. Injury Severity Score (ISS) was calculated by a single examiner for all patients on arrival in the emergency department. Patients were evaluated for age, sex, time of accident, blood alcohol level, ISS, days of ICU stay, ventilator use, hospital stay, mortality, head-chest-abdominal injury, fractures, number and type of surgical procedures, and total charges. Due to the Arizona Health Care Cost Containment System ( A H C C C S -

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PEDESTRIAN TRAUMA Brainard et al

FIGURE.

Surgical procedures.

~ the state's equivalent of Medicaid) structuring, patients frequently are assigned to providers at other facilities after discharge. Therefore, no meaningful assessment of long-term patient disability was possible in our study. Statistical analysis of the data collected was performed by X~, t test, or Pearson's correlation coefficient as indicated.

Neuro(10%) General(16%) Orthopedic(74%)

RESULTS The study was composed of 115 consecutive pedestrian motor vehicle accident victims, 83 (72%) of whom were men and 32 (28%) of w h o m were women. There were 647 motor vehicle accident trauma patients who presented to this institution during the study period. Tucson, Arizona, has one other Level I trauma center; during the study period, 89 motor vehicle accident patients were treated at that institution. These patients were not included in our analysis. Patients' ages ranged from 1 to 84 years (mean, 35 years). A majority of pedestrians (54%) were struck during the evening {6:00 PM to midnight), 29% during the day (8:00 AM to 6:00 PM), and 17% at n i g h t ( m i d n i g h t to 8:00 AM). Blood alcohol levels were obtained in the ED on 85 patients at the discretion of the treating physician. Detectable levels were recorded in 55 patients (65%) (mean level, 0.25 rag/ dL). The average age of the patients with measurable blood alcohol levels was 39 years, and their average ISS was 19. Nine of these patients died, a mortality rate of 16%. The average age of the patients with no detectable blood alcohol was 44 years, and their average ISS was 20. There were eight deaths, a 27% mortality ~cate. Alcohol level did not correlate with mortality or head injury (t test), ISS, or number of fractures (Pearson's correlation coefficient). There were 25 fatalities (22%) in our study, with 17 (68%) occurring during the initial resuscitative efforts. The mean ISS for all patients was 20. The average score for nonsurvivors was 46, with survivors averaging an ISS of 12. Of 98 patients hospitalized, 68 (69%) were sent to ICU, and 32 of those (47%) required ventilatory support (Table). These find136/882

ings were particularly evident in the elderly; the older the victim, the greater the mortality rate (P < .05, t test), the likelihood of fractures, the need for intensive care and ventilator support, and the need for prolonged hospitalization {P < .05, Pearson's correlation coefficient). However, increased age was not associated with higher ISS (P > .05, Pearson's correlation coefficient). Using the criteria established in the Abbreviated Injury Severity Score (AISS), patients had injuries to the head (34%), abdomen (21%) and chest (15%) and extremity-pelvis fractures (77%). There were a total of 227 fractures, an average of two per patient. The most common sites were tibiafibular fractures (39), followed by pelvis fractures (35) and femur fractures (31). The combination of head injury, pelvis-hip fracture, al~d knee injury was found in ten patients. One hundred eleven operative procedures were performed, of which 82 were orthopedic (usually fracture stabilization). General surgical procedures (18) and neurosurgical procedures (11) were performed less frequently (Figure). There was a strong correlation (P < .001, X2) with either a head, chest, or abdominal injury and death. Patients with chest or abdominal trauma were at increased risk for a head injury (P < .001, X2). In contrast, the presence of a pelvic or tibia-fibular fracture did not increase the likelihood of mortality or injury to the head, chest, or abdomen. Pedestrians sustaining femur fractures were at increased risk for abdominal trauma and pelvic fracture but not for accompanying tibiafibular fractures. A m o n g patients Annals of Emergency Medicine

hospitalized, the average stay was 11 days, with five days spent in ICU. Hospital, ED, and physician charges averaged $16,900 per patient.

DISCUSSION Analysis of the results shows that the victim of a pedestrian motor vehicle accident is usually a man in his 30s, frequently intoxicated, who is struck during the evening. McCarroll's review 4 of pedestrian fatalities showed a male predominance (75%), as h a v e m a n y o t h e r t r a u m a studies s 7 His New York City study group averaged 52 years old compared with 35 years old for the Tucson, Arizona, study group; 43% of those tested had detectable alcohol levels (although less than half were evaluated for this parameter4). In this study, nearly three fourths of the patients were screened for blood alcohol, and 55 (65%) had detectable levels. This is a much higher incidence of intoxication than is seen in studies of passenger car occupants, motorcyclists, and even other pedestrians.~ to The mean alcohol level in this study group (0.25 mg/dL) was also significantly higher than that reported in other trauma series. Ward et a] 11 found that a m o n g multiple trauma patients, 32% had d e t e c t a b l e alcohol levels, w i t h a mean level of .149 mg/dL. In this study, there was no statistically significant difference between the ISS of patients who had consumed alcohol and those who had not; however, those with detectable alcohol levels had a lower m o r t a l i t y rate and a higher incidence of head injury, t1 Despite the high incidence and level of alcohol intoxication in our study, 18:8 August 1989

TABLE. C r i t i c a l c a r e r e q u i r e m e n t s ICO

No. of Patients

Length of Stay (days)

31

1

Total

25

2-7

12

>7 Average

68

5.1

Ventilator Use

12

1

14

2-7

6 Total

32

t h e r e was no s t a t i s t i c a l l y s i g n i f i c a n t c o r r e l a t i o n b e t w e e n a l c o h o l l e v e l and m o r t a l i t y , ISS, h e a d injury, or t o t a l n u m b e r of fractures. P e d e s t r i a n s s t r u c k b% m o t o r vehicles h a v e t r a d i t i o n a l l y had h i g h m o r t a l i t y rates, and o u r s t u d y c o n f i r m s t h a t f i n d i n g . T h e m o r t a l i t y r a t e of 2 2 % in o u r s e r i e s is in a g r e e m e n t w i t h t h a t of o t h e r p u b l i s h e d series, w h i c h range f r o m 6% to 3 0 % . 4,I2,13 Neither this study nor the others c i t e d h a v e i n c l u d e d p e d e s t r i a n s declared dead at t h e scene. T h i s w o u l d suggest a higher actual mortality rate. A large p o r t i o n of t h e fatalities (68%) o c c u r r e d as a d i r e c t r e s u l t of t h e i n j u r i e s s u s t a i n e d at t h e t i m e of the accident rather than from late complications. As expected, the m e a n ISS of 20 w a s h i g h . S e v e r a l studies have documented that the p r o g n o s i s for s u r v i v a l is p o o r w h e n t h e ISS is m o r e t h a n 40.14, ~s T h e patient population in this study s h o w e d a s i m i l a r l y p o o r o u t l o o k , as o n l y one of 16 p a t i e n t s w i t h an ISS of m o r e t h a n 40 survived. A l t h o u g h t r a u m a affects p r i m a r i l y t h e young, its c o n s e q u e n c e s are part i c u l a r l y d e l e t e r i o u s for t h e elderly, is It is n o t surprising t h a t an i n c r e a s e in age r e s u l t e d in an i n c r e a s e d r i s k of mortality, fractures, and long-term specialized care. As with other t r a u m a , it is t h e head, chest, and abd o m i n a l i n j u r i e s t h a t are p a r t i c u l a r l y l e t h a l in t h e i m m e d i a t e p o s t i n j u r y period, e s p e c i a l l y w h e n o c c u r r i n g in c o m b i n a t i o n . M c C a r r o l l et al f o u n d 18:8 August 1989

REFERENCES

Duration of Use (days)

No. of Patients

>7 Average

t i m s r e p r e s e n t a s m a l l b u t l e t h a l category of m o t o r v e h i c l e t r a u m a . T h e y are c h a r a c t e r i z e d by m u l t i s y s t e m injury w i t h c o n c o m i t a n t h i g h ISS and m o r t a l i t y r a t e s , p a r t i c u l a r l y in t h e p e r i a c c i d e n t period. T h e p a t i e n t s suffer m u l t i p l e fractures t h a t f r e q u e n t l y r e q u i r e o p e r a t i v e t r e a t m e n t . T h e increased n e e d for o p e r a t i n g r o o m facilities, i n t e n s i v e care m o n i t o r i n g , and support c o m b i n e to m a k e t r e a t m e n t of t h e s e p a t i e n t s an e x p e n s i v e and prolonged proposition.

6.8

t h a t 80% of fatalities suffered signific a n t i n j u r i e s to t w o or m o r e b o d y areas; a l t h o u g h this s t u d y used a different c l a s s i f i c a t i o n s y s t e m , t h e findings w e r e similar. 4 If head, chest, or a b d o m i n a l t r a u m a is p r e s e n t , t h e physician must suspect additional m a j o r a r e a s of i n v o l v e m e n t . O t h e r than abdominal trauma associated w i t h f e m u r fracture, e x t r e m i t y fractures did n o t s h o w a s t a t i s t i c a l l y sign i f i c a n t c o r r e l a t i o n w i t h t r a u m a to t h e h e a d or trunk. W a d d e l l and D r u c k e r d e s c r i b e d ten p a t i e n t s w i t h a triad of h e a d injury, h i p - p e l v i s f r a c t u r e , and k n e e i n j u r y b u t did n o t i n d i c a t e t h e t o t a l n u m b e r of p e d e s t r i a n s e v a l u a t e d . 16 G a r l a n d et al i d e n t i f i e d this triad in six of 25 pedestrians who sustained head t r a u m a ; h o w e v e r , t h i s s u b s e t of pat i e n t s is n o t r e p r e s e n t a t i v e of t h e ent i r e p e d e s t r i a n t r a u m a p o p u l a t i o n . 17 This study showed a similar incid e n c e of t h e t r i a d a m o n g h e a d i n j u r e d p a t i e n t s (26%), b u t it was n o t s t a t i s t i c a l l y s i g n i f i c a n t as a charact e r i s t i c i n j u r y p a t t e r n a m o n g all ped e s t r i a n s s t r u c k by m o t o r v e h i c l e s . T h e i m p o r t a n c e of e x t r e m i t y fractures lies in t h e i r r e c o g n i t i o n d u r i n g t h e i n i t i a l r e s u s c i t a t i o n and p r o m p t t r e a t m e n t to p r o m o t e m o b i l i z a t i o n . CONCLUSION As w i t h a n y p a t i e n t s u s t a i n i n g multiple trauma, pedestrian motor v e h i c l e a c c i d e n t v i c t i m s place a significant demand on hospital and h e a l t h care resources. P e d e s t r i a n vic-

Annals of Emergency Medicine

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