Profiling pediatric patients involved in automobile crashes in Japan.

INTRODUCTION: There is little data concerning the injuries induced by being run over in children. PROBLEM: Characteristics of injuries suffered in children by being run over were investigated.
MATERIALS AND METHODS: Between January 1998 and December 2007, the medical charts were retrospectively reviewed to investigate characteristics of the injuries in pediatric patients run over by a car. Patients meeting the following criteria were included: (1) age ≤ 12 years old; (2) the patient was struck by an automobile. The subjects were divided into three groups by the mechanisms of injury: (1) run over; (2) carried away; (3) contact.
RESULTS: Twelve patients had been run over, 44 patients were carried away and 44 patients had been hit by a car (contact). The average age in the run over group was the lowest, followed by that in the carried away group and that in the contact group was the highest. The children's coma score and injury severity score were not significantly different among the three groups; however, the average chest abbreviated injury score was the highest in the run over group, followed by that in the carried away group and that in the contact group was the lowest. The average duration of admission and survival rate among three groups, were not significantly different.
CONCLUSION: The patients who were injured due to being run over by a car, tended to be younger and to have severe chest injury.

INTRODUCTION

Contact with a moving automobile can result in severe injury to the human body.[12] The severity of the injury depends on the speed and weight of the automobile.[13] Pedestrian injuries have three phases; the bumper impact, hood and windscreen impact and ground impact.[1] Each of these phases has a specific pattern of injury and is well studied.[1] However, there is little data concerning the injuries induced by being run over.[45] Hence, the characteristics of injuries suffered in children by being run over were investigated.

MATERIALS AND METHODS

Between January 1998 and December 2007, the medical charts were retrospectively reviewed for the all blunt trauma patients who were treated in the emergency department. Patients meeting the following criteria were included: (1) age ≤12 years old; (2) injured in an automobile accident when walking or on a bicycle. Individual medical records were reviewed with regard to the following data: sex, age, mechanism of injury, the place of accident, vital signs on arrival (systolic blood pressure, heart rate, children's coma score)[6], abbreviated injury score (AIS)[7], injury severity score (ISS)[7], type of injury, treatment, duration of admission and survival rate. The children's coma score (Raimondi) was evaluated by the ocular, verbal and motor response. The maximum score assignable is 11 and minimal 3. The subjects were divided into three groups based on the mechanisms of injury: (1) run over; (2) carried away (struck by an automobile and the impact carried the subject at least 1 m away from the scene); (3) contact. The variables mentioned above were investigated in the three groups. A statistical analysis was performed using contingency table analyses, a one-way factorial analysis of variance and the Kruska-Wallis test. Fisher's PLSD post hoc test was used to determine significant differences (P<0.05).

RESULTS

A total of 169 patients with blunt trauma whose age ≤12 years old were identified. The causes of the injuries are described in Table 1 shows among these patients, 44 patients were injured by being carried away, 44 patients by contact and 12 patients war run over. These patients were analyzed as subjects. All of the subjects that were run over, were run over by a car not a truck.

Table 1

Cause of injury

Table 2 shows the results of the place of the accident. The most common location of an accident in the group of patients that were run over by an automobile was at an intersection and while walking along the side of the road. Three subjects were run over when a car was backing up. There was no such case in the two other groups. The most common location of an accident in the carried away group was while crossing the street. Collisions at intersections were the most common locations of accidents in which the patient was struck by a car. These differences were significant.

Table 2

Place of accident

Table 3 shows the results of a comparison among the three mechanisms of injury. The average age in the run over group was the lowest, followed by that in the carried away group and that in the contact group increase was the highest [run over group (average 4.5-years old: 95% confidence interval (CI) 3.6–5.4 years old), carried away group (average 6.7-years old: 95% CI 5.9–7.4 years old), contact group (average 8.1-years old: 95% CI 7.3-8.8 years old)]. The sex and systolic blood pressure were not significantly different among the three groups. The average heart rate was the highest in the run over group, followed by that in the carried away group and that in the contact group was the lowest [the run over group (average 150.0/minute: 95% CI 138.4–161.6/minute), the carried away group (average 115.9/minute: 95% CI 109.2–122.6/minute), the contact group (average 103.0/minute: 95% CI 96.9–109.1/minute)]. The Children's Coma Score and ISS were not significantly different among the three groups; however, the average chest AIS was highest in the run over group, followed by that in the carried away group and that in the contact group decrease was the lowest [the run over group (average 1.1: 95% CI 0.8–1.4), the carried away group (average 0.5: 95% CI 0.3–0.7), the contact group (average 0.1: 95% CI 0.0–0.2)]. The average head AIS was lowest in the run over group, followed by that in the contact group and that in the carried away group decrease was the lowest [the run over group (average 0.7: 95% CI 0.4–1.1), the contact group (average 1.8: 95% CI 1.6–2.0), the carried away group (average 2.0: 95% CI 1.8–2.2)].

Table 3

Comparison among the different mechanisms of automobile injury

The direct injuries associated with being run over except for skin lesion coding AIS = 1, are summarized in Table 4. The number of lung contusions was greatest in the run over group, followed by liver injury. There was one patient who underwent a skin graft for a degloving injury in the run over group. There were three patients who underwent intracranial surgery and one patient who underwent an internal fixation for a tibial fracture in the carried away group. There were four patients who underwent intracranial surgery and one patient who underwent an internal fixation for a femur fracture in the contact group. The average duration of admission and the survival rate among three groups were not significantly different.

Table 4

Summary of the direct injuries suffered after being run over except for skin lesion (AIS = 1)

There was one 7-year-old male patient, who had isolated head injury by being run over, which included skull fracture, cerebral contusion and diffuse cerebral swelling resulting in respiratory arrest followed by cardiac arrest. After resuscitation, the patient regained spontaneous circulation and thereafter was admitted to the hospital, but later died of brain death 4 days after admission. All of the subjects who died in the other group also died due to head injury.

DISCUSSION

This study showed that the patients who were injured by being run over tended to be younger and to also have severe chest injuries. If the head of the patient had not been not run over, then the outcome tended to be favorable.

Previous reports have analyzed a variety of injury such as traumatic asphyxia,[89] open pelvic fracture,[10] head injury,[11] liver injury,[12] degloving injury,[13] anogenital injuries,[14] neck injury[15] and chest injury,[16] that occurred when children were run over. Bell et al., summarized 14 injury cases resulting from being run over.[4] In their report, there were eight cases of lung contusions and this injury was the most common in comparison to other injuries, as observed in the current study. Generally, the trunk and head in a child accounts for a greater portion of the body than those in an adult. In addition, patients often fall down after a collision with a car and the position of head is farther from the car in comparison to his or her trunk. Accordingly, there is a greater proportion of the trunk in close proximity to the car, which might tend to induce more frequent body injuries in comparison with other points (head, extremity) of injury.

The average age in the run over group was the smallest among the three groups. Bell et al., also reported that the average age of children run over was 3-years old.[4] This might be because the younger children are smaller so that driver could not see them, thus they are more frequently run over in comparison to older children. In addition, a small child has a lower center of gravity so that they fall down easily, or a small child cannot move quickly to avoid collision with an automobile. These may explain why younger children are more likely to be run over.

The current study demonstrated that the average heart rate was the highest in the run over group. As a newborn begins in life with a rapid heart which gradually slows down over time, and the average age in the run over group was the smallest among the three groups, and this might simply reflect a negative correlation between age and heart rate.

The outcome of a run over injury may depend on the incidence of head injury. Bell et al., reported that only one patient died due to head injury induced by being run as observed in the current study.[4] Takeshi et al. reported seven cases of head crush injury.[11] Among them, six cases were induced by being run over or backed over and three of the six died of the head injury itself. In contrast, in animal experiments, no animal survived compression by five times its own weight for longer than 10 mins;[17] however, weights of up to 2-7 tons have been tolerated for short periods in humans.[8] Accordingly, trunk injuries incurred by being run over seem to have favorable outcomes if the automobile was not too heavy and the duration of being run over was short.[48918]

As all subjects who died in this study died of head injury, it may be necessary for all children that go outside of home might need put on helmets to prevent death due to automobile accident including being run over. However, we could not compare the findings of subjects who wore helmet with those who did not, because no law exists in Japan to ensure that children wear helmets, even when riding a bicycle in Japan. Accordingly, we could not comment on any useful preventable methods based on the results of the current study.

CONCLUSIONS

The patients who were injured by being run over tended to be younger and to have severe chest injuries. If the head of the patient was not run over and the duration of the time being run over was short, then the outcome tended to be favorable.