Mortality and head injury: The pediatric perspective

Mortality and Head Injury: The Pediatric Perspective By J.J. Tepas III, Carla DiScala, M a x L. R a m e n o f s k y , and Barbara B a r l o w Jacksonville, Florida 9 The records of 10,098 children entered into the National Pediatric Trauma Registry (NPTR) w e r e analyzed to define the characteristics of pediatric head injury and the impact of extracranial trauma on Central Nervous System (CNS) injury. The 4,400 NPTR head injuries w e r e then compared with 16,524 head injuries recently reported from a predominantly adult trauma registry to illustrate potential population differences. Results indicate that children have a lower mortality, that the addition of axtracranial injury significantly reduces recovery potential, that CNS injury is the predominant and most common cause of pediatric traumatic death, and that the automobile is the most lethal component of a child's environment. 9 1990 by W.B. Saunders Company'. INDEX injury,

WORDS:

Pediatric trauma;

head injury;

brain

(AIS) as defined by the Association for the Advancement of Automotive Medicine (AAAM). 2 This universally accepted coding scheme categorizes degree of injury severity on a scale of 1 to 6 a s indicated in Table 1. Its applicability to pediatric injury was recently confirmed by review of the original authors with a panel of pediatric surgical and neurosurgical specialists. 3 Outcome was measured by mortality and the number of functional impairments recorded at discharge. The relationship between AIS and mortality for this population was then compared with that recently reported for a cohort of 16,524 head-injured patients recorded in a predominantly adult database. ~ The contribution of extracranial injury to outcome for adults and children was assessed by comparing mortality for each category of isolated head injury with the same category in ECI. Differences were compared for statistical significance as measured by Chi square analysis and Fisher's exact test. RESULTS

ENTRAL NERVOUS system (CNS) injury is the most devastating component of childhood trauma. It is the leading cause of death of the injured child and produces immeasurable suffering, both in functional disability and in diminished quality of life. This report describes pediatric head injury as recorded in the National Pediatric Trauma Registry (NPTR), compares it with a recent report from the predominantly adult Major Trauma Outcome Study (MTOS),I and analyzes its relationship to extracranial injury.

C

MATERIALS AND METHODS

The records of 10,098 patients entered into the NPTR were analyzed to identify those children with head injury alone (HI), those with head and extracranial injury (ECI), and those with extracranial injury only (N). The bead injury groups were then evaluated by comparing mechanisms of injury, presenting neurological status, overall injury severity; and outcome. Presenting status was assessed by admission systolic blood pressure, by initial Glasgow COMA Scale (GCS) and by intensity of initial therapeutic intervention as indicated by endotracheal intubation. Injury severity was compared using the 1985 version of the Abbreviated Injury Scale

From the Division of Pediatric Surgery, University of Florida Health Science Center, Jacksonville, FI. Supported by US Department of Education, Grant No. G008300042, National Pediatric Trauma Registry and Maternal and Child Health Grant No. I3-127, Florida Emergency Medical Services for Children Demonstration Project. Presented at the 20th Annual Meeting of the American Pediatric Surgical Association, Baltimore, Maryland, May 28-31, 1989. Address reprint requests to J.J. Tepas 1/1, MD, Division of Pediatric Surgery, University of Florida, Health Science Center Jacksonville, 655 W. 8th St, Jacksonville, FL 32209. 9 1990 by W.B. Saunders Company. 0022-3468/90/2501-0016503.00/0 92

Epidemiology (NPTR) Table 2 illustrates the distribution of adult and pediatric patients by head injury categories. Forty-four percent of the injured children sustained head injury versus 33% of the adult population (P < .0001). The pediatric group demonstrated the usual 2:1 male to female ratio for those sustaining head injury alone or in combination with other systemic trauma. Forty percent of HI and ECI were young children (age < 5 years) versus 33% in the group without head trauma. The proportion of infants (age < 1 year) with head trauma was three times larger than in the group without head injury. The most common mechanisms of injury for the entire pediatric group were fall (37.5%), motor vehicle (18.3%), pedestrian (17.2%), and bicycle (9.9%). The majority of fatal injuries occurred as a result of automotive mishaps, either as pedestrian or as passenger (Fig 1).

Presenting Status Injury severity significant enough to warrant immediate endotracheal intubation (and presumably hyperventilation) occurred in 20% of ECI versus only 10% of HI. Neurological dysfunction on presentation was Table 1. Abbreviated Injury Scale Code

Severity

1 2 3 4 5 6

Minor Moderate Serious Severe (survivable) Critical (7 survivable) Unsurvivable

Journal of Pediatric Surgery, Vo125, No 1 (January), 1990: pp 92-96

93

MORTALITY FROM PEDIATRIC HEAD INJURY

Table 2. Distribution of Injury Catagories HI

Adult (MTOS) (%) HI ECI N

Mortality(%)

Ped (NPTR)(%)

Mortality(%)

3,O61 (6.2) 13,463 (27.3) 32,619 (66.3)

23.1 17.1 6.1

2,113 (20.9) 2,287 (22.6) 5,698 (56.4)

5.5 7.1 0.7

Total 49,143 (100)

10.1

10,098 (100)

3.1

ECI

categorized as severe (GCS 3 to 7), moderate (GCS 8 to 13), or minimal (GCS 14 to 15). The proportion of ECI presenting with moderate or severe CNS dysfunction (45.1%) was twice that of children with isolated head injury (23.4%) (P < .0001, Fig 2). Analysis of the 117 fatalities in HI compared with 165 in ECI demonstrated no difference in distribution of admission systolic blood pressures (Table 3).

Injury Severity Versus Mortality--Adult Versus Child Table 4 demonstrates the effect of increasing AIS severity of pure head injury on mortality for pediatric versus adult patients. While mortality is lower for the pediatric population, it is significantly so for AIS 3 (Chi Square, 63.03; P < .0001) and 4 (Chi Square, 44.38; P < .0001), which represent moderate and severe degrees of injury, respectively. The impact of ECI is demonstrated in Table 5. Increasing severity of head injury (columns) in association with increasing severity of the extracranial injury (rows) produces progressively higher mortality in both children and adults. The incidence of severe extracranial injury differs significantly in the pediatric population in that only 26% of extracranial injuries were potentially severe (AIS 3 to 6) versus 48% in the adult group (P > .001). For both the pediatric and adult population, increasing severity of the head injury produced more significant impact on mortality. However, the impact of extracranial injury is more notable in the pediatric population where the addition of increasing extracranial trauma almost doubles mortality (Fig 3). ECI

vs

HI

HI

m

Lmd

m

ECI

3-7

8-13

14-15

G(~ Cotlor t

Fig 2.

Presenting GCS indicates increased ECl severity.

Impairment at Discharge As potential for mortality begins at AIS 3, so also does the likelihood of discharge impairment. Table 6 demonstrates the incidence of impairment at discharge for HI versus ECI and illustrates the two to fourfold increase caused by extracranial injury. The incidence of severe handicap (four or more new impairments at discharge) was increased by the addition of moderate extracranial injury (AIS 3) to head injury with AIS of 3 or less (Table 7). In cases of severe head injury (AIS 4 or 5), no appreciable increase above that caused by head injury alone could be appreciated. The number of children with severe extracranial injury (AIS >__4) and minor head injury was too small to analyze reliably. DISCUSSION

Head injury is a very common component of pediatric trauma. 4 Kraus et al estimate that over 100,000 children a year sustain CNS injury severe enough to warrant hospital admission.5 The actual impact of head injury as the sole cause of pediatric mortality, and as a contributor to fatal outcome, has never been well defined. This is primarily the result of different studies focusing on the problem from different perpsectives. Mayer and Walker identified a significant mortality rate in patients with severe brain injury, which they defined as those children with a presenting GCS of 8 or less.6 Kraus et al, on the other hand, reviewed the experience with pediatric head injury in San Diego County during the year 1981 and identified an extremely low incidence of severely injured patients as indicated by similar GCS criteria. 5 Mortality from head injury, per se, has been reported to be as high as 21% and as low as 1% to 2%. This study identifies an Table 3. Distribution of Initial Systolic Blood Pressure--Fatalities

Fig 1.

Mechanisms of fatal injury, ECl versus HI.

ECI HI

N

>140

165 117

12% 13%

90-139 38% 32%

50-89

<50

Missing

28% 28%

15% 13%

6% 6%

94

TEPAS ET AL

:

Table 4. Percent Mortality for Pure Head Injury Abbreviated InjuryScale Adult Pediatric

No.

2

3

4

5

6

3061 2113

0.7 0

18.4 0.3

31.2 2.3

69.3 61.9

93 94

0,6

overall mortality rate from head injury of 6%, which is clearly lower than the adult cohort to which these patients were compared. Moreover, the incidence of mortality for increasing degrees of CNS injury as indicated by the AIS identifies the pediatric population as having better potential for survival than their adult counterparts. This observation was also reported by Luerssen et al in a series of 8,814 patients admitted to 41 hospitals in three major metropolitan areas. 7 This study included 1,906 pediatric patients whose survival in relation to the adult cohort was significantly better. Only when severe head injury was associated with hypotension or intracerebral bleed was the pediatric mortality similar to that of the adults. The influence of age on recovery was also documented by Stablein et al in their evaluation of prognostic determinants of head injury,s Logistic regression analysis of data from 115 patients indicated that age was second only to need for surgical decompression as a predictor of outcome. It would thus appear from this data and from other studies that the pediatric patient does indeed have a significantly greater physiological reserve in regard to potential for recovery from injury to the C N S . 7"9 It would also appear, however, that a significant proportion of pediatric head injury occurs as a component of poly-system trauma and that the contribution of the extracranial component of the injury pattern may exert a significant effect on overall survival of the child. As indicated in Fig 3 this additive effect is most apparent for mid-range levels of extracranial injury which, by themselves, usually have a negligible mortality. In this regard the relationship between intracranial and extracranial injury appears to differ between the child and the adult. When the contribution of extracranial injury to increasing degrees of intracranial injury is compared with the contribution of intracranial injury to increasing extracranial injury severity in the

,

,

,

9

,

9

t, IS

Fig 3. Impact of extracranial injury: &, effect of increasing head injury on mortality of extracranial; ~ , effect of increasing extracranial severity on mortality of head injury; + , pure head injury.

adult population, it becomes obvious that the mortality rate in these injury combinations is primarily driven by the presence of increasing severity of head injury? However, in the pediatric population, a similar relationship does not exist (Fig 4). A comparison of the pediatric component of Tables 4 and 5 suggests that the addition of minor extracranial injury to minor intracranial injury essentially doubles the mortality for those two cohorts of patients. Although the actual numbers of patients in these categories was quite small, the number of deaths increased fourfold in AIS 3 and twofold for head injury of AIS 4. It thus appears that the combination of head injury and extracranial injury in the pediatric population does indeed contribute to poor outcome from the intracranial injury. This particular observation was also noted by Mayer and Walker in their assessment of severe head injury and was used by them to emphasize to the emergency physician the importance of expeditious and efficient management of all the child's injuries to minimize the contribution of relatively minor injuries to poor outcome. 6 The need for intubation on arrival in the emergency department was used as an indicator of severity on presentation since it equates not only with a degree of injury that mandates intensive intervention, but also because it represents an essential first step in the management of a multiply injured child. The contribution of extracranial injury is clearly demonstrated by

Table 5. Percent Mortality by Increasing AIS Pediatric

Adult

Head

A2

A3

A4

A5

A6

P2

P3

P4

P5

P6

EC 1 EC 2 EC 3 EC 4 EC 5 EC 6

0.4 1.1 3 12 21 70

6.5 12 20 41.7 62.4 92.3

22.6 19.2 30.4 45.6 58.2 95

55.3 54.2 48.7 68.3 71.4 92.3

100 93.8 100 100 95.7 100

0 0 0.6 4.5 0 100

1.4 0 2 20 43

1.8 3.9 5 31 67

38.2 39.1 51.2 64 60 100

100 100 82 100 100

NOTE. A2 to A6, increasing AIS for adult head injury; P2 to P6, increasing AIS for pediatric head injury; EC, AIS of extracranial component of ECI,

MORTALITY FROM PEDIATRIC HEAD INJURY

95 1

Table 6. Incidence of Discharge With One or More Impairments A I S (H)

1

2

3

4

5

HI ECI

3% 23%

2% 25%

11% 43%

17% 53%

79% 82%

13.8

/

0.6

0,4

Table 7. Percent of Children With 4 or More New Impairments at Discharge Head AIS

1

2

3

4

5

ECI 1 ECI 2 ECI 3 ECI 4 ECI 5

0% 0% 4% 0% 0%

0% 1% 3% 5% 0%

1% 8% 20% 33% 25%

11% 31% 31% 11% 100%

71% 65% 81% 78% 63%

02

0

the doubling of the necessity for intubation in this patient cohort. This is especially interesting in light of the similarity of distribution of presenting systolic blood pressures for ECI and HI. If simple exsanguination caused by an associated extracranial injury were the major contributing factor to mortality, the proportion of ECI presenting with shock or hypotension should have been significantly different from HI. The fact that this was not so may be explainable by the type of extracranial injuries seen in the pediatric population since the actual proportion of extracranial injuries of a moderate to severe degree is half of what was reported in the adult population. It may also relate to differing mechanisms of injury seen in adult trauma patients, as well as to the overall primacy of C N S injury as a major component of pediatric trauma care. Although mortality is a major factor in pediatric trauma care morbidity after convalescence is an even more significant factor in regard to long-term care and quality of life. 4'~~Here again the relationship between increasing degrees of extracranial injury severity and functional discharge impairment illustrates the impact of extracranial injury on worsening outcome. The addition of a minor extracranial injury to a minor head injury increases the percentage of children who are discharged with disability as defined by four or more functional impairments. The combination of severe

Fig 4. Impact of extracranial injury: I~-I, pediatric head with increasing extracranial injury; + , pediatric extracranial with increasing head injury; &, adult extracranial, with increasing head injury; r%~3,adult head with increasing extracranial injury.

extracranial injury with severe intracranial injury, however, makes no difference in this proportion suggesting that the primary determinant is the head injury. This study illustrates the role of C N S injury as the primary component of pediatric trauma care, and confirms the following observations: (1) Overall survival from head injury is better in the pediatric population than in the adult. (2) C N S injury is the major factor impacting on outcome in the pediatric population. (3) C N S injury is the most common cause of death in the pediatric trauma population. (4) The addition of even a minor extracranial injury to head injury may have significant consequence in regard to mortality and discharge impairment. (5) The automobile continues to be the most lethal component of the child's environment. Since the overall survival of the head-injured child is significantly better than that of his adult counterpart and since the contribution of extracranial injury is more marked in the pediatric population, it becomes obvious that aggressive management of the child, strict attention to details relating to extracranial injury management, and basic life support of C N S function are the essential ingredients for improvement of pediatric trauma care.

REFERENCES

1. Gennarelli TA, Champion HR, Sacco WJ, et al: Mortality of patients with head injury and extracranial injury treated in trauma centers. J Trauma 29:1193-1202, 1989 2. Committee on Injury Scaling of the American Association for Automotive Medicine: The Abbreviated Injury Scale (1985 Revision). Arlington Heights, IL, 1985 3. Baker SB: Personal communication, August 1986 4. Casey R, Ludwig S, McCormick M: Morbidity following minor head trauma in children: Pediatrics 78:497-502, 1986 5. Kraus JF, Fife D, Conroy C: Pediatric brain injuries: The nature, clinical course, and early outcomes in a defined United States' population. Pediatrics 79:501-507, 1987 6. Mayer TA, Walker ML: Pediatric head injury: The critical

role of the emergency physician. Ann Emerg Med 14:1178-1184, 1985 7. LuerssenTG, Klauber MR, Marshall LF: Outcome from head injury related to patient's age: A longitudinal prospectivestudy of adult and pediatric head injury. J Neurosurg 68:409-416, 1988 8. Stablein DM, Miller JD, Choi SC: Statistical methods for determining prognosis in severe head injury. Neurosurgery 6:243248, 1980 9. Kraus JF, Fife D, Cox P: Incidence, severity, and external causes of pediatric brain injury. Am J Dis Child 140:687-693, 1986 10. Lundar T, Nestvold K: Pediatric head injuries caused by traffic: A prospective study with five-year follow-up. Childs Nerv Syst 1:24-28, 1985

96

TEPAS ET AL

Discussion D. Wesson (Toronto, Ontario): Two quick questions. Why isn't there a third peak in the children? Trunkey's article in Scientific American was reported to show a distinct late mortality peak resulting from renal failure, respiratory failure, etc. Why don't we see that? I also have a comment. We have just finished doing a follow-up study which showed in fact that impairment at discharge does not necessarily predict impairment at 6 months. I would like to ask you about the feasibility of including late outcome data in at least a portion of the Pediatric Trauma Registry. J. Alex Hailer (Baltimore, CA): I have not been entirely happy with Dr Tepas' Pediatric Trauma Score only because it does not weight the head injury enough. Now he has come forward with some beautiful data to show that there is no question but that head injury is the key factor in survival. As Dr Tepas has also pointed out, the PTS score is not intended for triage, but as a measure of injury severity. My question then is, now that the data is in, do you plan to modify your Pediatric Trauma Score so that you will give a higher number, that is greater weight, to the head injury as a determinate in survival? J.J. Tepas (closing): To answer the question about impairment first, this has been a very difficult issue and, in fact, we have devised a method of assessing that which uses impairment at discharge on a much simpler scale. I discussed it yesterday and would only reiterate that we must have long-term follow-up. Discharge impairment, as measured by the presence of a cast or loss of a limb function temporarily, is far different than discharge impairment measured by loss of cognitive function. This is the hot topic because the mortality rate overall of pediatric trauma, at least what we see, is low. The morbidity rate as measured by long-term disability and handicap is significant. We have some of that information and intend t~embark on a pilot study

using the N P T R to analyze that on a long-term basis. The third peak does exist, but it appears to be very, very far out. At least that has been my understanding. When I looked at mortality, there was a very small cohort of patients who do indeed die 6 weeks, 8 weeks, 2 months, 3 months later, probably as a result of their CNS dysfunction. I have been studying multiple organ system failure in the nursery and in the PICU. Since we are a level I trauma center, I have a very interesting control in our adults, and, in fact, we don't see the same spectrum of disease. 1, therefore, think there is a third peak, but I think it is a very small one. I did not show the data, Dr Haller, that looked at the triage ability of the Pediatric Trauma Score in regard to this because I discussed it yesterday. If you look at increasing AIS, the proportion of patients who would be triaged (with a PTS of 8) to a trauma center goes up exactly parallel and about 20% higher than the mortality rate, suggesting a very high sensitivity. When we evaluate the Glasgow Coma Score in relation to PTS, we get the same factor. So, we are not planning on modifying it. It seems to work quite well. In regard to the question regarding population bias, as you end up with a large population, you may approach but will not achieve a population-based study. There is no question that this study does not represent every injured child in this country. There are kids dying in very small towns that we know nothing about, but this report does represent the disease that we see. Finally, in answer to Dr Harris' question, and thanking him for his kind comments, the reason we used the AIS was as a quantitator of injury severity, not to create the quadratic equation produced by the ISS. It just let us put these into the separate grades of severity which have been well understood and well accepted throughout the past 20 years of trauma and injury research.