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Severity of illness and injury in pediatric air transport
ORIGINAL CONTRIBUTION air transport, pediatric; pediatric, air transport
Severity of Illness and Injury in Pediatric Air Transport To assess severity of illness or injury m pediatric patients undergoing air transport, we prospectively evaluated 636 patients during 29 months of service. All patients were classified by age, diagnosis, and method and distance of transport. Therapeutic intervention scoring system (TISS) scores were calculated in all patients, Glasgow coma scale (GCS) scores were used in patients with altered level of consciousness, and Modified Injury Severity Scale (MISS) scores were used in patients with multiple trauma. A total of 57.5% of patients were transported by helicopter, 37.5% by fixed-wing aircraft, and 5% by ground transport. Mean distance of transport was 207 miles. Age ranged from 3 weeks to 16 years, with 45% of children under 1 year of age. Trauma (24.6%), neurologic disease (24.2%), and respiratory failure (20%) were the most common diagnoses. Eighty-one percent of patients were taken to surgery or admitted to the intensive care unit immediately on arrival at the regional children's hospital. Mean TISS score was 36.7, with 51% of patients having TISS scores greater than 30. The mean MISS score was 34.5, and 75% of patients had MISS scores greater than 25. Nineteen percent of patients had GCS scores less than or equal to 8. Overall mortality was 7%, with 9% mortality in patients with trauma versus 6.3% in nontraumatic diseases. TISS scores greater than 30, MISS scores greater than 25, and GCS scores less than or equal to 8 were associated with increased mortality (P < .01). [Mayer TA, Walker ML: Severity of illness and injury in pediatric air transport. Ann Emerg Med February 1984;13:108-111.]
INTRODUCTION In recent years, significant emphasis has been placed on regionalization of certain aspects of critical care, including major trauma, head injury, bums, spinal cord injury, and pediatrics. The need for rapid and expert transportation to specialized centers has led to the development of air transport programs in many areas of the country. While these programs have received popular support and have undoubtedly been beneficial to many of the patients who have been transported, detailed analyses of the costs and benefits from air transport programs are lacking. We have reported a cost analysis of one such program, indicating that transportation could be delivered without exorbitant cost to the patient or the hospital. 1 Because air transport systems involve a great deal of time, effort, and expense, such systems should responsibly account for the type and number of patients transported. Ideally air transport and regionalization of pediatric care should be limited to those patients with serious illnesses or injuries, z To assess the severity of illness or injury in pediatric patients transported by an air transport system, we prospectively evaluated 636 patients treated during the initial 29 months of operation of the Pediatric LifeFlight service of the Primary Children's Medical Center, Salt Lake City.
Thom A Mayer, MD* Ft Lauderdale, Florida Marion L Walker, MD1Salt Lake City, Utah From the Department of Emergency Medicine, North Broward Hospital District, Ft Lauderdale, Florida, and the Departments of Pediatrics and Emergency Medicine, Georgetown University School of Medicine, Washington, DC;* and the Departments of Pediatrics and Neurosurgery, Primary Children's Medical Center, University of Utah College of Medicine, Salt Lake City.lPresented at the University Association for Emergency Medicine Annual Meeting in Boston, June'1983. Received for publication April 25, 1983. Revision received June 27, 1983. Accepted for publication August 15, 1983. Address for reprints: Thom A Mayer, MD, Coastal Group, Inc, 1500 Cypress Creek Road, NW, Ft Lauderdale, Florida 33309.
METHODS During a 29-month period (April 1979 through August 1981) all patients transported by the Pediatric LifeFlight program were classified prospectively according to age, diagnosis, and method and distance of transport. Depending on the patient's condition, either a physician and flight nurse or two flight nurses were sent on transport. All physicians and nurses had undergone in-
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PEDIATRIC AIR TRANSPORT Mayer & Walker
tensive, comprehensive training, and were able to perform endotracheal intubation, needle or tube thoracostomy, and intravenous cutdowns. In all patients therapeutic intervention scoring s y s t e m 3 (TISS) scores were calculated during the first 24 hours of admission to the regional children's hospital. The TISS system included assignment of four point interventions for cerebral intracranial pressure monitoring and diuresis for treatment of intracranial hypertension. In patients with neurologic injuries or altered level of consciousness, Glasgow c o m a scale 4 (GCS) scores were utilized as an index of severity, In p a t i e n t s w i t h m u l t i p l e t r a u m a (trauma to two or more body areas), modified injury severity scale 5 (MISS) scores were assessed. All patients were e v a l u a t e d at a m i n i m u m of six m o n t h s after illness or injury and were classified by the Glasgow outcome scale. 6 This scale classifies patients as normal, moderate disability, severe disability, vegetative survival, or death. Data were subjected to chi-square analysis with Yates' correction w h e n appropriate. RESULTS During the 29-month study period, 636 patients were transported by the Pediatric LifeFlight program. Rotarywing transport (helicopter) was used in 57.5% of cases; fixed-wing transport was used in 37.5% of cases; and an additional 5% of transports were effected by ground ambulance when weather precluded safe flight or when transport distances were less than 25 miles. Scene transports accounted for less than 1% of the total, and all scene transports were done for major multiple trauma. T h e m e a n distance of transport was 207 miles, with 51% of patients t r a n s p o r t e d less t h a n 150 miles. The mean transport distance was 452 miles for fixed-wing aircraft, 82 miles for helicopter, and 21 miles for ground ambulance. Patient age ranged from 3 weeks to 16 years; 45% were less than 1 year of age, 34% were between 1 and 5 years old, and 21% were more than 5 years old. D i a g n o s t i c c a t e g o r i e s are listed (Table 1). Trauma accounted for 24.6% of transports, with 9.3% due to multiple trauma and 15.3% due to isolated head injury, Neurologic diseases accounted for 24.2% of transports, while respiratory failure or i n f e c t i o n ac58~09
TABLE 1. Diagnosis in 636 air transport patients Diagnosis Head injury Multiple trauma Neurologic illness Respiratory failure/infection Gastrointestinal/genitourinary Metabolic disease Cardiovascular General pediatric surgical
counted for 20%. Only 6% of patients had a diagnosis of cardiovascular disease.
Severity of Injury Five hundred fifteen patients (81%) were taken to surgery or to the intensive care unit immediately on arrival at the regional children's hospital. TISS scores are listed (Table 2). The mean TISS score was 36.7. Seventyfour percent of patients had scores of 20 or more, 51% had scores greater than 30, and 30% had scores over 40. More than half the patients with TISS scores less than 20 were referred for complex pediatric surgical procedure. In patients with multiple trauma, MISS scores ranged from 5 to 59, with a mean of 34.5. Approximately 75% (119 of 156 patients) had MISS scores greater than or equal to 25. A m o n g those patients with MISS scores less than 25, 90% were referred for neurosurgical evaluation and 75% had GCS scores less than or equal to 8. Overall, 119 patients (19%) had GCS scores less than or equal to 8.
Outcome Outcome data are shown (Table 3). Overall mortality was 7%, with 9% mortality in patients with trauma versus 6.3% in patients with nontraumatic diseases. Two percent of patients had severe disability and 5.5% had moderate disability. Of the 7.5% who were disabled, more than 90% suffered multiple trauma, head injury, or other severe neurologic insults (near drowning, m e n i n g i t i s , Reye's syndrome, etc). There were 33 deaths in 325 pat i e n t s (10% m o r t a l i t y ) w i t h TISS scores greater than or equal to 30, while there were 12 deaths in 311 patients (4%) with scores less than 30 (P < .01). Of 117 p a t i e n t s w i t h MISS scores greater than or equal to 25, 11% Annals of Emergency Medicine
n
%
97 59 153 132 64 57 38 36
15.3 9.3 24.2 20.1 10.2 9.2 6 5.7
died; only one of 39 patients (2.6%) with scores less than 25 died. In patients with severe neurologic injury {GCS less than or equal to 8) mortality was 14.3%; mortality was 3.6% in patients with GCS scores greater than 8 {P< .01).
Ground Versus Air Transport Only 5% of patients (n = 32) were t r a n s p o r t e d by g r o u n d a m b u l a n c e , usually when transport distances were less than 25 miles or when weather precluded safe flight. Because the m e a n transport distance for ground ambulance was 21 miles, it is apparent that distance was the more c o m m o n reason for selecting ground transport. Further, less than 1% of patients were transported from the scene of accident, all of which were for a diagnosis of major trauma. Because of the small n u m b e r of p a t i e n t s t r a n s p o r t e d by ground ambulance, it was impossible to compare statistically severity of illness or injury and outcome in ground versus air transport patients. However, the diagnoses of ground a m b u l a n c e patients were remarkably similar to those transported by air. With regard to outcome, three patients (9.4%) died following ground transport.
DISCUSSION In an era in which more than 10% of the gross national product is spent on health care, the r e i m b u r s e m e n t s t r u c t u r e for h e a l t h care costs is changing rapidly, and competition for the health care dollar is increasing, it is incumbent upon professionals and health planners to account responsibly for the costs of critical care services and the outcome of patients. This is p a r t i c u l a r l y t r u e for p r o g r a m s in w h i c h major i n v e s t m e n t s of time, effort, and expense are involved, such as air transport systems for critically ill or injured patients. These systems 13:2 February 1984
TABLE 2. TISS* scores (mean = 36.7) TISS score
n
%
i> 40 30-39 20-29 10-19 < 10
191 134 146 134 31
30 21 23 21 5
*Therapeutic Intervention Scoring System.
TABLE 3. Outcome data Category
n
% Mortality
Overall Trauma Nontraumatic
45 14 31
7 9 6.3
GCS* <~ 8 GCS > 8
17 28
14.3 3.6§
TISSt I> 30 TISS < 30
33 12
10§ 4
MISS:~ ~> 25 MISS < 25
13 1
11 2.5§
*Glasgow Coma Scale. 1-Therapeutic Intervention Scoring System. ~Modified Injury Severity Scale, §P < .01.
are expensive, with start-up costs exceeding $200,000.7 In a p r e v i o u s study, 1 we noted that air transport costs were within 1% of ground transportation costs when distances were between 25 and 200 miles, and that air transport was performed at considerably less cost for distances greater than 200 miles. While that report detailed cost concerns, it did not specifically assess the severity of illness or injury in p a t i e n t s u n d e r g o i n g air transport. Baxt and Moody 8 recently compared ground versus helicopter transport in 300 trauma patients transported from the scene of injury in San Diego. They found a statistically significant decrease in predicted mortality in patients transported by helicopter compared to ground ambulance. Further, the major impact of their program was on patients with the most severe injuries. Their air transport program emphasizes the i m p o r t a n c e of rapid provision of a well-trained physician13:2 February1984
nurse team to trauma patients at the scene of injury. In our pediatric air transport program, the majority of patients (99%) are referred after initial triage at referring hospitals. Thus the emphasis in our program has been on rapid provision of expert pech'atrlc care to patients with serious illnesses or injuries, whether at the referring hospital or at the scene of injury. Our intent in this study was to assess prospectively the severity of illness or injury in pediatric patients undergoing air transport. The underlying assumption was that such transport should be limited largely to patients with critical illness. To address this topic, we sought to use benchmarks of severity that had been previously studied in detail. Numerous indices of severity have been developed and validated for patients with acute illnesses or diseases, including those w i t h m u l t i p l e trauma,5, 9-11 altered level of consciousness, 4 general m e d i c a l or surgical disease, g,12 and burns. 13 We chose to evaluate our patients by scales whose efficiency had been verified by previous studies. The TISS score, originally described by C u l l e n 14 and m o d i f i e d by others,14A5 has been shown to be of value in classifying both adult and pediatric patients requiring intensive care.3,1s, 16 This score uses the type,and number of monitoring and therapeutic interventions to assess the overall severity of disease. The APACHE (Acute Physiology and Chronic Health Evaluation) 12 classification has also been useful in evaluating illness, but has only recently been adapted for use in pediatric patients.17 For this reason, we felt the TISS system was better suited for our patients. The injury severity scale score, originally described by Baker et al, 9 has been validated by studies in both this and other countries, lo We previously described a modification of the ISS (MISS) which was intended to improve the classification of head injuries.S, is Because this scale has been shown to be an accurate index of severity in pediatric patients w i t h multiple trauma, 5 it was used to classify such patients. The Glasgow coma scale score was used to describe patients with neurologic illness or injury. The GCS score has gained wide acceptance following detailed evaluation at m a n y centers worldwide.4,5,19 While necessarily imprecise, we also characterized patients by admisAnnals of Emergency Medicine
sion to the intensive care unit or immediate surgery on arrival at the regional children's hospital. Finally, outcome was assessed by the Glasgow outcome scale. Data from our study indicate clearly that the majority of pediatric patients transported by our air transport system did have severe illness or injury. Depending on the scale used, between 74% and 81% of patients had serious illness or injury. Seventy-four percent of patients had TISS scores greater than or equal to 20. Among patients with scores less than 20, more than half were referred for complex pediatric surgical procedures. Previous studies of the TISS in pediatric patients have indicated that increasing TISS scores are associated with increased morbidity and mortality, ls-lz and that scores above 10 correlated statistically w i t h poorer survival. 16 Previous studies have d o c u m e n t e d that MISS or TISS scores over 25 were associated with poorer outcome.5,1o, is In our series, approximately 75% of those with multiple trauma had MISS scores over 25. Further, in patients with scores less than 25, 90% were referred specifically for neurosurgical evaluation and 75% had a GCS score less than or equal to 8. The multi-center study by Gennarelli et a119 clearly documents that head-injured patients with GCS scores less than 8 have m u c h greater morbidity and mortality. Overall 19% of our patients had GCS scores less than or equal to 8. As indicated previously, 81% of all patients were taken either to the operating room or to the intensive care unit immediately on arrival at the regional children's hospital. While this is an imprecise index, it does give a general sense of the clinical assessment of severity of illness or injury. Considerations of time, geography, or the need for specialized tertiary care may be justifications for air transport. By far the most c o m m o n reason for choosing air transport has been the shorter time required for air transport when patients are long distances from the hospital. In certain cases, geography (whether in urban or rural settings) m a y also m a k e air transport preferable to ground transport. However, a critical factor in jusifying the effective use of air transport is the concept of providing well-trained teams of physicians and nurses at the earliest possible time. This is particularly true in pediatric patients, w h o often re110/59
PEDIATRIC AIR TRANSPORT Mayer & Walker
quire m e d i c a l e x p e r t i s e t h a t is unavailable at outlying hospitals. In this regard, one critical issue is n o t h o w long it takes the child to arrive at the regional p e d i a t r i c center, b u t r a t h e r how long it takes the center's expert care to be delivered to the child. The rapid provision of such expert patient care teams can be costly. For that reason, such care should be limited to patients with severe illnesses or injuries. It was for this reason that we sought to document the severity of illness or injury in the patients using our air transport system. A much more difficult question (and one that is not answered by this study) is "Does air transport improve o u t c o m e of p a t i e n t s u s i n g t h e system?" Answering this question would require a randomized trial of both patients transported from the scene of injury and those referred from outlying hospitals. As indicated, the small number of ground ambulance patients in our study precludes significant statistical analysis of ground versus air t r a n s p o r t p a t i e n t s . N o n e t h e l e s s , we currently a t t e m p t to deliver the physic i a n - n u r s e t e a m to t h e p a t i e n t and back to the tertiary care center by the fastest yet safest possible means. Further study m a y prove that the clearest advantage of air transport programs relates more to the advanced modalities of patient care (as well as continuity and standardization of such care) delivered by well-trained physiciannurse flight teams than to the method of t r a n s p o r t itself. F u r t h e r s t u d y of ground ambulance versus air transport will be necessary to clarify this matter. A n a d d i t i o n a l p o i n t t h a t deserves emphasis is outcome in this series of patients. Overall m o r t a l i t y was 7%, w i t h 9% m o r t a l i t y in patients w i t h multiple trauma or head injury versus 6.3% mortality in patients with nont r a u m a t i c d i s e a s e s . D e a t h a n d disability were more c o m m o n in patients with head injury or severe neurologic insult than in patients w i t h other diagnoses. MISS scores greater than or equal to 25 and TISS scores greater than or equal to 30 were associated with poorer outcome (P ~ .01). Comparison of these outcome data
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with those from other institutions is complicated by a n u m b e r of factors. Our series was l i m i t e d to p a t i e n t s w h o were referred by air t r a n s p o r t , and was not a systematic study of the i n t e n s i v e care u n i t p a t i e n t s at our children's hospital. Thus our study design specifically selected out those patients who had survived their initial illness or i n j u r y a n d h a d been stabilized to the extent that they were able to undergo air transport. In addition, we had a m u c h lower percentage of patients with cardiovascular disease and congenital malformations. Nonetheless t h e overall m o r t a l i t y of 7% probably compares favorably w i t h the studies by Yeh et a116 (10% mortality) and Rothstein et a115 (18% mortality).
SUMMARY The majority of patients transported by this system had serious illness or injury, as assessed by the MISS, GCS, and TISS scoring systems or by the need for i m m e d i a t e intensive care or surgical intervention. Compared w i t h other studies of severely ill or injured p e d i a t r i c p a t i e n t s , o u t c o m e in this group of patients was acceptable, w i t h an overall m o r t a l i t y of 7%. Nevertheless, further studies comparing outcome in patients transported by air versus ground a m b u l a n c e are necessary to clarify w h e t h e r air transport improves outcome.
Jack Gallagher, EdD, reviewed the data and provided invaluable statistical assistance.
REFERENCES 1. Black R, Mayer T, Walker ML, et al: Air transport of pediatric emergency patients. N Engl J Med 1982;307:1485-1488. 2. Mayer T: Transportation of the injured child, in Mayer T (ed}: Emergency Management of Pediatric Trauma. Philadelphia, WB Saunders Co, in press, 1984. 3. Keene AR, Cullen DJ: Therapeutic intervention scoring system: Update 1983. Crit Care Med 1983;11:1-3. 4. Jennett B, Teasdale G, Galbraith S, et al: Severe head injuries in three countries. J Neurol Neurosurg Psychiatry 1977;40: 291-298.
Annals of Emergency Medicine
5. Mayer T, Walker ML, Clark P: Further experience with the modified abbreviated injury severity scale. J Trauma 1984, in press. 6. Jennett B, Bond M: Assessment of outcome after severe brain damage. A practical scale. Lancet 1975;1:480-484. 7. Cooper MA, Klippel AP, Seymour JA: A hospital-based helicopter service: Will it fly? Ann Emerg Med 1980;9:451-455. 8. Baxt W, Moody P: The impact of a rotor craft aeromedical emergency care service on trauma mortality. JAMA 1983; 249:3047-3051. 9. Baker 8P, O'Neill B, Hadden W Jr, et al: The injury severity scale score: A method for describing patients with multiple injuries and evaluating emergency care. J Trauma 1974;14:187-196. 10. Bull JP: The injury severity score of road traffic casualties. Accid Anal Prey 1975;7:249-255. ll. Champion H, Sacco W, Carnazzo AJ, et al: The trauma score. Crit Care Med 1981;9:672-676. 12. Knaus WA, Zimmerman JE, Wagner DP, et al: APACHE - - Acute Physiology and Chronic Health Evaluation: A physiologically based classification system. Crit Care Med 1981;9:951. 13. Edlich R~ Larkham N, O'Hanlan JT, et al: Modification of the American Burn Association injury severity grading system. JACEP 1978;7:226. 14. Cullen DJ, Civetta JM, Briggs BA, et al: Therapeutic intervention scoring system: A method for quantitative comparison of patient care. Crit Care Med 1974; 2:57-60. 15. Rothstein P, Johnson P: Pediatric intensive care. Factors that influence outcome. Crit Care Med 1982;10:34-37. 16. Yeh TS, Pollack MM, Holbrook PR, et al: Assessment of pediatric intensive care - - Application of the therapeutic intervention scoring system. Crit Care Med 1982;10:497-500. 17. Pollack MM, Yeh TS, Ruttiman U, et al: Validation of the physiologic stability index for critically ill infants and children. Crit Care Med 1983;11:216. 18. Mayer T, Matlak ME, Johnson OG, et al: The modified injury severity scale in pediatric multiple trauma patients. J Pediatr Surg 1980;15:719-726. 19. Gennarelli TA, Speilman GM, Langfitt TW, et al: Influence of the type of intracranial lesion on outcome from severe head injury. J Neurosurg 1982;56:26-32.
13:2 February 1984
Severity of Illness and Injury in Pediatric Air Transport To assess severity of illness or injury m pediatric patients undergoing air transport, we prospectively evaluated 636 patients during 29 months of service. All patients were classified by age, diagnosis, and method and distance of transport. Therapeutic intervention scoring system (TISS) scores were calculated in all patients, Glasgow coma scale (GCS) scores were used in patients with altered level of consciousness, and Modified Injury Severity Scale (MISS) scores were used in patients with multiple trauma. A total of 57.5% of patients were transported by helicopter, 37.5% by fixed-wing aircraft, and 5% by ground transport. Mean distance of transport was 207 miles. Age ranged from 3 weeks to 16 years, with 45% of children under 1 year of age. Trauma (24.6%), neurologic disease (24.2%), and respiratory failure (20%) were the most common diagnoses. Eighty-one percent of patients were taken to surgery or admitted to the intensive care unit immediately on arrival at the regional children's hospital. Mean TISS score was 36.7, with 51% of patients having TISS scores greater than 30. The mean MISS score was 34.5, and 75% of patients had MISS scores greater than 25. Nineteen percent of patients had GCS scores less than or equal to 8. Overall mortality was 7%, with 9% mortality in patients with trauma versus 6.3% in nontraumatic diseases. TISS scores greater than 30, MISS scores greater than 25, and GCS scores less than or equal to 8 were associated with increased mortality (P < .01). [Mayer TA, Walker ML: Severity of illness and injury in pediatric air transport. Ann Emerg Med February 1984;13:108-111.]
INTRODUCTION In recent years, significant emphasis has been placed on regionalization of certain aspects of critical care, including major trauma, head injury, bums, spinal cord injury, and pediatrics. The need for rapid and expert transportation to specialized centers has led to the development of air transport programs in many areas of the country. While these programs have received popular support and have undoubtedly been beneficial to many of the patients who have been transported, detailed analyses of the costs and benefits from air transport programs are lacking. We have reported a cost analysis of one such program, indicating that transportation could be delivered without exorbitant cost to the patient or the hospital. 1 Because air transport systems involve a great deal of time, effort, and expense, such systems should responsibly account for the type and number of patients transported. Ideally air transport and regionalization of pediatric care should be limited to those patients with serious illnesses or injuries, z To assess the severity of illness or injury in pediatric patients transported by an air transport system, we prospectively evaluated 636 patients treated during the initial 29 months of operation of the Pediatric LifeFlight service of the Primary Children's Medical Center, Salt Lake City.
Thom A Mayer, MD* Ft Lauderdale, Florida Marion L Walker, MD1Salt Lake City, Utah From the Department of Emergency Medicine, North Broward Hospital District, Ft Lauderdale, Florida, and the Departments of Pediatrics and Emergency Medicine, Georgetown University School of Medicine, Washington, DC;* and the Departments of Pediatrics and Neurosurgery, Primary Children's Medical Center, University of Utah College of Medicine, Salt Lake City.lPresented at the University Association for Emergency Medicine Annual Meeting in Boston, June'1983. Received for publication April 25, 1983. Revision received June 27, 1983. Accepted for publication August 15, 1983. Address for reprints: Thom A Mayer, MD, Coastal Group, Inc, 1500 Cypress Creek Road, NW, Ft Lauderdale, Florida 33309.
METHODS During a 29-month period (April 1979 through August 1981) all patients transported by the Pediatric LifeFlight program were classified prospectively according to age, diagnosis, and method and distance of transport. Depending on the patient's condition, either a physician and flight nurse or two flight nurses were sent on transport. All physicians and nurses had undergone in-
13:2 February 1984
Annals of Emergency Medicine
108/57
PEDIATRIC AIR TRANSPORT Mayer & Walker
tensive, comprehensive training, and were able to perform endotracheal intubation, needle or tube thoracostomy, and intravenous cutdowns. In all patients therapeutic intervention scoring s y s t e m 3 (TISS) scores were calculated during the first 24 hours of admission to the regional children's hospital. The TISS system included assignment of four point interventions for cerebral intracranial pressure monitoring and diuresis for treatment of intracranial hypertension. In patients with neurologic injuries or altered level of consciousness, Glasgow c o m a scale 4 (GCS) scores were utilized as an index of severity, In p a t i e n t s w i t h m u l t i p l e t r a u m a (trauma to two or more body areas), modified injury severity scale 5 (MISS) scores were assessed. All patients were e v a l u a t e d at a m i n i m u m of six m o n t h s after illness or injury and were classified by the Glasgow outcome scale. 6 This scale classifies patients as normal, moderate disability, severe disability, vegetative survival, or death. Data were subjected to chi-square analysis with Yates' correction w h e n appropriate. RESULTS During the 29-month study period, 636 patients were transported by the Pediatric LifeFlight program. Rotarywing transport (helicopter) was used in 57.5% of cases; fixed-wing transport was used in 37.5% of cases; and an additional 5% of transports were effected by ground ambulance when weather precluded safe flight or when transport distances were less than 25 miles. Scene transports accounted for less than 1% of the total, and all scene transports were done for major multiple trauma. T h e m e a n distance of transport was 207 miles, with 51% of patients t r a n s p o r t e d less t h a n 150 miles. The mean transport distance was 452 miles for fixed-wing aircraft, 82 miles for helicopter, and 21 miles for ground ambulance. Patient age ranged from 3 weeks to 16 years; 45% were less than 1 year of age, 34% were between 1 and 5 years old, and 21% were more than 5 years old. D i a g n o s t i c c a t e g o r i e s are listed (Table 1). Trauma accounted for 24.6% of transports, with 9.3% due to multiple trauma and 15.3% due to isolated head injury, Neurologic diseases accounted for 24.2% of transports, while respiratory failure or i n f e c t i o n ac58~09
TABLE 1. Diagnosis in 636 air transport patients Diagnosis Head injury Multiple trauma Neurologic illness Respiratory failure/infection Gastrointestinal/genitourinary Metabolic disease Cardiovascular General pediatric surgical
counted for 20%. Only 6% of patients had a diagnosis of cardiovascular disease.
Severity of Injury Five hundred fifteen patients (81%) were taken to surgery or to the intensive care unit immediately on arrival at the regional children's hospital. TISS scores are listed (Table 2). The mean TISS score was 36.7. Seventyfour percent of patients had scores of 20 or more, 51% had scores greater than 30, and 30% had scores over 40. More than half the patients with TISS scores less than 20 were referred for complex pediatric surgical procedure. In patients with multiple trauma, MISS scores ranged from 5 to 59, with a mean of 34.5. Approximately 75% (119 of 156 patients) had MISS scores greater than or equal to 25. A m o n g those patients with MISS scores less than 25, 90% were referred for neurosurgical evaluation and 75% had GCS scores less than or equal to 8. Overall, 119 patients (19%) had GCS scores less than or equal to 8.
Outcome Outcome data are shown (Table 3). Overall mortality was 7%, with 9% mortality in patients with trauma versus 6.3% in patients with nontraumatic diseases. Two percent of patients had severe disability and 5.5% had moderate disability. Of the 7.5% who were disabled, more than 90% suffered multiple trauma, head injury, or other severe neurologic insults (near drowning, m e n i n g i t i s , Reye's syndrome, etc). There were 33 deaths in 325 pat i e n t s (10% m o r t a l i t y ) w i t h TISS scores greater than or equal to 30, while there were 12 deaths in 311 patients (4%) with scores less than 30 (P < .01). Of 117 p a t i e n t s w i t h MISS scores greater than or equal to 25, 11% Annals of Emergency Medicine
n
%
97 59 153 132 64 57 38 36
15.3 9.3 24.2 20.1 10.2 9.2 6 5.7
died; only one of 39 patients (2.6%) with scores less than 25 died. In patients with severe neurologic injury {GCS less than or equal to 8) mortality was 14.3%; mortality was 3.6% in patients with GCS scores greater than 8 {P< .01).
Ground Versus Air Transport Only 5% of patients (n = 32) were t r a n s p o r t e d by g r o u n d a m b u l a n c e , usually when transport distances were less than 25 miles or when weather precluded safe flight. Because the m e a n transport distance for ground ambulance was 21 miles, it is apparent that distance was the more c o m m o n reason for selecting ground transport. Further, less than 1% of patients were transported from the scene of accident, all of which were for a diagnosis of major trauma. Because of the small n u m b e r of p a t i e n t s t r a n s p o r t e d by ground ambulance, it was impossible to compare statistically severity of illness or injury and outcome in ground versus air transport patients. However, the diagnoses of ground a m b u l a n c e patients were remarkably similar to those transported by air. With regard to outcome, three patients (9.4%) died following ground transport.
DISCUSSION In an era in which more than 10% of the gross national product is spent on health care, the r e i m b u r s e m e n t s t r u c t u r e for h e a l t h care costs is changing rapidly, and competition for the health care dollar is increasing, it is incumbent upon professionals and health planners to account responsibly for the costs of critical care services and the outcome of patients. This is p a r t i c u l a r l y t r u e for p r o g r a m s in w h i c h major i n v e s t m e n t s of time, effort, and expense are involved, such as air transport systems for critically ill or injured patients. These systems 13:2 February 1984
TABLE 2. TISS* scores (mean = 36.7) TISS score
n
%
i> 40 30-39 20-29 10-19 < 10
191 134 146 134 31
30 21 23 21 5
*Therapeutic Intervention Scoring System.
TABLE 3. Outcome data Category
n
% Mortality
Overall Trauma Nontraumatic
45 14 31
7 9 6.3
GCS* <~ 8 GCS > 8
17 28
14.3 3.6§
TISSt I> 30 TISS < 30
33 12
10§ 4
MISS:~ ~> 25 MISS < 25
13 1
11 2.5§
*Glasgow Coma Scale. 1-Therapeutic Intervention Scoring System. ~Modified Injury Severity Scale, §P < .01.
are expensive, with start-up costs exceeding $200,000.7 In a p r e v i o u s study, 1 we noted that air transport costs were within 1% of ground transportation costs when distances were between 25 and 200 miles, and that air transport was performed at considerably less cost for distances greater than 200 miles. While that report detailed cost concerns, it did not specifically assess the severity of illness or injury in p a t i e n t s u n d e r g o i n g air transport. Baxt and Moody 8 recently compared ground versus helicopter transport in 300 trauma patients transported from the scene of injury in San Diego. They found a statistically significant decrease in predicted mortality in patients transported by helicopter compared to ground ambulance. Further, the major impact of their program was on patients with the most severe injuries. Their air transport program emphasizes the i m p o r t a n c e of rapid provision of a well-trained physician13:2 February1984
nurse team to trauma patients at the scene of injury. In our pediatric air transport program, the majority of patients (99%) are referred after initial triage at referring hospitals. Thus the emphasis in our program has been on rapid provision of expert pech'atrlc care to patients with serious illnesses or injuries, whether at the referring hospital or at the scene of injury. Our intent in this study was to assess prospectively the severity of illness or injury in pediatric patients undergoing air transport. The underlying assumption was that such transport should be limited largely to patients with critical illness. To address this topic, we sought to use benchmarks of severity that had been previously studied in detail. Numerous indices of severity have been developed and validated for patients with acute illnesses or diseases, including those w i t h m u l t i p l e trauma,5, 9-11 altered level of consciousness, 4 general m e d i c a l or surgical disease, g,12 and burns. 13 We chose to evaluate our patients by scales whose efficiency had been verified by previous studies. The TISS score, originally described by C u l l e n 14 and m o d i f i e d by others,14A5 has been shown to be of value in classifying both adult and pediatric patients requiring intensive care.3,1s, 16 This score uses the type,and number of monitoring and therapeutic interventions to assess the overall severity of disease. The APACHE (Acute Physiology and Chronic Health Evaluation) 12 classification has also been useful in evaluating illness, but has only recently been adapted for use in pediatric patients.17 For this reason, we felt the TISS system was better suited for our patients. The injury severity scale score, originally described by Baker et al, 9 has been validated by studies in both this and other countries, lo We previously described a modification of the ISS (MISS) which was intended to improve the classification of head injuries.S, is Because this scale has been shown to be an accurate index of severity in pediatric patients w i t h multiple trauma, 5 it was used to classify such patients. The Glasgow coma scale score was used to describe patients with neurologic illness or injury. The GCS score has gained wide acceptance following detailed evaluation at m a n y centers worldwide.4,5,19 While necessarily imprecise, we also characterized patients by admisAnnals of Emergency Medicine
sion to the intensive care unit or immediate surgery on arrival at the regional children's hospital. Finally, outcome was assessed by the Glasgow outcome scale. Data from our study indicate clearly that the majority of pediatric patients transported by our air transport system did have severe illness or injury. Depending on the scale used, between 74% and 81% of patients had serious illness or injury. Seventy-four percent of patients had TISS scores greater than or equal to 20. Among patients with scores less than 20, more than half were referred for complex pediatric surgical procedures. Previous studies of the TISS in pediatric patients have indicated that increasing TISS scores are associated with increased morbidity and mortality, ls-lz and that scores above 10 correlated statistically w i t h poorer survival. 16 Previous studies have d o c u m e n t e d that MISS or TISS scores over 25 were associated with poorer outcome.5,1o, is In our series, approximately 75% of those with multiple trauma had MISS scores over 25. Further, in patients with scores less than 25, 90% were referred specifically for neurosurgical evaluation and 75% had a GCS score less than or equal to 8. The multi-center study by Gennarelli et a119 clearly documents that head-injured patients with GCS scores less than 8 have m u c h greater morbidity and mortality. Overall 19% of our patients had GCS scores less than or equal to 8. As indicated previously, 81% of all patients were taken either to the operating room or to the intensive care unit immediately on arrival at the regional children's hospital. While this is an imprecise index, it does give a general sense of the clinical assessment of severity of illness or injury. Considerations of time, geography, or the need for specialized tertiary care may be justifications for air transport. By far the most c o m m o n reason for choosing air transport has been the shorter time required for air transport when patients are long distances from the hospital. In certain cases, geography (whether in urban or rural settings) m a y also m a k e air transport preferable to ground transport. However, a critical factor in jusifying the effective use of air transport is the concept of providing well-trained teams of physicians and nurses at the earliest possible time. This is particularly true in pediatric patients, w h o often re110/59
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quire m e d i c a l e x p e r t i s e t h a t is unavailable at outlying hospitals. In this regard, one critical issue is n o t h o w long it takes the child to arrive at the regional p e d i a t r i c center, b u t r a t h e r how long it takes the center's expert care to be delivered to the child. The rapid provision of such expert patient care teams can be costly. For that reason, such care should be limited to patients with severe illnesses or injuries. It was for this reason that we sought to document the severity of illness or injury in the patients using our air transport system. A much more difficult question (and one that is not answered by this study) is "Does air transport improve o u t c o m e of p a t i e n t s u s i n g t h e system?" Answering this question would require a randomized trial of both patients transported from the scene of injury and those referred from outlying hospitals. As indicated, the small number of ground ambulance patients in our study precludes significant statistical analysis of ground versus air t r a n s p o r t p a t i e n t s . N o n e t h e l e s s , we currently a t t e m p t to deliver the physic i a n - n u r s e t e a m to t h e p a t i e n t and back to the tertiary care center by the fastest yet safest possible means. Further study m a y prove that the clearest advantage of air transport programs relates more to the advanced modalities of patient care (as well as continuity and standardization of such care) delivered by well-trained physiciannurse flight teams than to the method of t r a n s p o r t itself. F u r t h e r s t u d y of ground ambulance versus air transport will be necessary to clarify this matter. A n a d d i t i o n a l p o i n t t h a t deserves emphasis is outcome in this series of patients. Overall m o r t a l i t y was 7%, w i t h 9% m o r t a l i t y in patients w i t h multiple trauma or head injury versus 6.3% mortality in patients with nont r a u m a t i c d i s e a s e s . D e a t h a n d disability were more c o m m o n in patients with head injury or severe neurologic insult than in patients w i t h other diagnoses. MISS scores greater than or equal to 25 and TISS scores greater than or equal to 30 were associated with poorer outcome (P ~ .01). Comparison of these outcome data
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with those from other institutions is complicated by a n u m b e r of factors. Our series was l i m i t e d to p a t i e n t s w h o were referred by air t r a n s p o r t , and was not a systematic study of the i n t e n s i v e care u n i t p a t i e n t s at our children's hospital. Thus our study design specifically selected out those patients who had survived their initial illness or i n j u r y a n d h a d been stabilized to the extent that they were able to undergo air transport. In addition, we had a m u c h lower percentage of patients with cardiovascular disease and congenital malformations. Nonetheless t h e overall m o r t a l i t y of 7% probably compares favorably w i t h the studies by Yeh et a116 (10% mortality) and Rothstein et a115 (18% mortality).
SUMMARY The majority of patients transported by this system had serious illness or injury, as assessed by the MISS, GCS, and TISS scoring systems or by the need for i m m e d i a t e intensive care or surgical intervention. Compared w i t h other studies of severely ill or injured p e d i a t r i c p a t i e n t s , o u t c o m e in this group of patients was acceptable, w i t h an overall m o r t a l i t y of 7%. Nevertheless, further studies comparing outcome in patients transported by air versus ground a m b u l a n c e are necessary to clarify w h e t h e r air transport improves outcome.
Jack Gallagher, EdD, reviewed the data and provided invaluable statistical assistance.
REFERENCES 1. Black R, Mayer T, Walker ML, et al: Air transport of pediatric emergency patients. N Engl J Med 1982;307:1485-1488. 2. Mayer T: Transportation of the injured child, in Mayer T (ed}: Emergency Management of Pediatric Trauma. Philadelphia, WB Saunders Co, in press, 1984. 3. Keene AR, Cullen DJ: Therapeutic intervention scoring system: Update 1983. Crit Care Med 1983;11:1-3. 4. Jennett B, Teasdale G, Galbraith S, et al: Severe head injuries in three countries. J Neurol Neurosurg Psychiatry 1977;40: 291-298.
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5. Mayer T, Walker ML, Clark P: Further experience with the modified abbreviated injury severity scale. J Trauma 1984, in press. 6. Jennett B, Bond M: Assessment of outcome after severe brain damage. A practical scale. Lancet 1975;1:480-484. 7. Cooper MA, Klippel AP, Seymour JA: A hospital-based helicopter service: Will it fly? Ann Emerg Med 1980;9:451-455. 8. Baxt W, Moody P: The impact of a rotor craft aeromedical emergency care service on trauma mortality. JAMA 1983; 249:3047-3051. 9. Baker 8P, O'Neill B, Hadden W Jr, et al: The injury severity scale score: A method for describing patients with multiple injuries and evaluating emergency care. J Trauma 1974;14:187-196. 10. Bull JP: The injury severity score of road traffic casualties. Accid Anal Prey 1975;7:249-255. ll. Champion H, Sacco W, Carnazzo AJ, et al: The trauma score. Crit Care Med 1981;9:672-676. 12. Knaus WA, Zimmerman JE, Wagner DP, et al: APACHE - - Acute Physiology and Chronic Health Evaluation: A physiologically based classification system. Crit Care Med 1981;9:951. 13. Edlich R~ Larkham N, O'Hanlan JT, et al: Modification of the American Burn Association injury severity grading system. JACEP 1978;7:226. 14. Cullen DJ, Civetta JM, Briggs BA, et al: Therapeutic intervention scoring system: A method for quantitative comparison of patient care. Crit Care Med 1974; 2:57-60. 15. Rothstein P, Johnson P: Pediatric intensive care. Factors that influence outcome. Crit Care Med 1982;10:34-37. 16. Yeh TS, Pollack MM, Holbrook PR, et al: Assessment of pediatric intensive care - - Application of the therapeutic intervention scoring system. Crit Care Med 1982;10:497-500. 17. Pollack MM, Yeh TS, Ruttiman U, et al: Validation of the physiologic stability index for critically ill infants and children. Crit Care Med 1983;11:216. 18. Mayer T, Matlak ME, Johnson OG, et al: The modified injury severity scale in pediatric multiple trauma patients. J Pediatr Surg 1980;15:719-726. 19. Gennarelli TA, Speilman GM, Langfitt TW, et al: Influence of the type of intracranial lesion on outcome from severe head injury. J Neurosurg 1982;56:26-32.
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