Aeromedical evacuation of rural victims of nontraumatic cardiac arrest

EMS/ORIGINAL CONTRIBUTION aeromedical evacuation

A

_/-&.eromedical Evacuation of Rural Victims of Nontraumatic Cardiac Arrest

From the Division of Emergency Medicine, Department of Medicine, University of Virginia Health Sciences Center, Charlottesville. Received for publication March 24, 1992. Revision received November 16, 1992. Accepted for publication December 3, 1992. Presented at the Association of Air Medical Services Scientific Section in Tampa, Florida, October i991; and the Southern Medical Association Scientific Assembly in Atlanta, Georgia, November i99i.

George H Lindbeck, MD David S Groopman, MD Robert D Powers, MD

Study objectives: To determine if the deployment of a helicopter-borne nurse/paramedic team contributed to survival of victims of nontraumatic cardiac arrest in a rural setting. Design: Retrospective chart review. Setting: A university hospital-based helicopter aeromedical program serving a primarily rural region with a volunteer basic life support/advanced life support ground emergency medical services system.

Participants: Victims of nontraumatic cardiac arrest, older than 15 years, in cardiac arrest at the time of request for air evacuation.

Measurements and main results: Eighty-four patients were identified who met the study inclusion criteria between January 1, 1986, and December 31, 1989. Basic life support care was always available before aeromedical crew arrival; advanced life support care was available in 58% of cases before helicopter arrival. Resuscitative efforts were terminated in the field in 55 cases; of 29 patients transported to the emergency department, only ten (12%)survived to hospital admission. Only one patient (1%) survived to hospital discharge; this patient was resuscitated by ground advanced life support providers before helicopter arrival. Conclusion: Despite providing improved availability of advanced life support care in some cases, deployment of aeromedical teams had a negligible effect on patient survival from nontraumatic cardiac arrest in a rural setting. [Lindbeck GH, Groopman DS, Powers RD: Aeromedical evacuation of rural victims of nontraumatic cardiac arrest. Ann Emerg MedAugust 1993;22:1258-1262.]

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INTRODUCTION

Patients suffering cardiac arrest require the rapid initiation of basic life support (BLS) measures, followed in a narrow time frame by advanced life support (ALS) care, for mortality to be affected. ~-5 Aeromedical programs have been viewed as a mechanism for augmenting local emergency medical services (EMS) resources by rapidly providing advanced levels of care at the scene of illness or injury This concept has been particularly attractive in rural areas, where response times of ground units to calls for help are longer than in suburban or urban areas, EMS agencies often are staffed by volunteer crews, and local ALS resources may be limited. Although the use of aeromedical services as a component in a system for the coordinated management of trauma victims has been described, their role in augmenting ALS care in the prehospital management of acute medical illness remains undefined. The purpose of this study was to analyze the experience of an aeromedical program with the deployment of helicopter-borne nurse/paramedic teams responding to assist lodal EMS providers in the care of victims of nontraumatic cardiac arrest in a rural setting.

December 31, 1989, were reviewed to identify instances when the helicopter was requested to be dispatched to the scene of a patient in cardiac arrest. "Scene" flights were defined as those to locations other than EDs, including doctor's offices or health care facilities without ALS care. Only cases in which the patient was in cardiac arrest at the time of request/dispatch were included. Patients who arrested following trauma and those 15 years of age or younger were excluded. Once cases were identified, flight records, ED charts, and hospital records were reviewed to obtain the following information: the time course of successive phases of the flight, distance, availability of BLS and ALS care, circumstances of the arrest, estimated "down" time before BL5 care, estimated time to ALS care, procedures performed by the helicopter crew, disposition, and outcome of the patient. The outcome end points of death or discharge from the hospital were chosen. A favorable outcome from the introduction of aeromedical services would be expected to result in similar if not improved survival rates compared with those reported in comparable systems. Charges to the patient for flight services were estimated using charges in effect at the time.

MATERIALS AND METHODS

The Pegasus air transport program is operated by the University of Virginia Health Sciences Center, a 650-bed Level I trauma center and tertiary care referral center with an annual adult emergency department volume of approximately 44,000 visits. The nine-county area (3,833 square miles) primarily served by the program for scene flights is largely rural, with some suburban areas and small towns. The estimated population of these nine counties was 240,000 in the 1990 census. The flight program began operations in fall 1984 and pursued a policy of responding to all requests for scene flights from authorized EMS, fire, or law enforcement agencies regardless of the reported nature of the patients' illness or i n j u ~ The flight program operated an MBB BK 117 helicopter staffed by a registered nurse and a nationally registered paramedic during the period of the study. The ground EMS system serving the area is a tiered volunteer system, providing levels of care from firstresponder through Virginia cardiac technician certification. Many ALS technicians have been trained in endotracheal intubation. Data were gathered by chart review. Flight records were maintained on a computer data base (Aero Med Software ®, Innovative Eng{neering, Hood, Virginia) beginning in 1986. All flights between January 1, 1986, and

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RESULTS

During the period of January 1, 1986, to December 31, 1989, the Pegasus air transport program completed 2,410 flights, of which 1,003 (42%) were scene flights. Of these, 84 cases were identified that met the inclusion criteria. There were 54 male and 30 female patients. The mean age was 58.3 years (+ 17.8 years), with a range of 18 to 99 years. Patients were "found down" in 34 cases (41%); arrests were observed by bystanders in 34 cases (41%), by rescue squad crews in 12 instances (13%), and in health care settings in four cases (5%). The predominant previously existing major illnesses or immediate factors contributing to the arrest, if identified, are shown (Table). Review of flight characteristics revealed that the mean response time (dispatch to fiftoff) was 4.9 minutes (_+_2.4 minutes; range, one to eight minutes). The average distance traveled was 22 miles (+ 8.6 miles; range, four to 44 miles), and the average flight time was 12.9 minutes (+ 4.3 minutes; range, four to 29 minutes). Seventy-nine flights (94%) were to field locations, and five (6%) were to physicians' offices (four) or a nursing home (one). The average on-scene time was 35.6 minutes (_+ 17.5 minutes; range, four to 81 minutes). Estimating the time of the arrest, and hence "down" time before BLS measures and time to availability of ALS

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care, was difficult because of inadequate information in many prehospital records. In 53 cases (63°/O), there was specific reference to the estimated time of arrest by bystanders or the arrest was observed by rescue squad crew members or other health care providers. The mean time to BLS measures in this group was 5.77 minutes (+ 8.86 minutes; range, zero to 40 minutes). In 31 cases, no confident estimate could be made. In 51 cases in which times were recorded, the estimated mean time to ALS care was 15.8 minutes (+ 15.68 minutes; range, zero to 51 minutes). Fifteen Patients with evaluable time records suffered an arrest while in the presence of prehospital ALS providers. CPR was initiated by bystanders in 25% of cases, by first arriving rescue squad crews in 68% of cases, by nurse or physician health care providers in 6% of cases, and by fire department first-responders in one case (1%). Of 65 cases in which the patient's care could have been initiated by bystanders (found down, observed by bystanders, or in three cases of drowning), CPR was initiated by bystanders in 21 instances (32% of opportunities). The aeromedical team provided the first available ALS care in 35 cases (42%); the mean time to ALS care in those instances was 33.6 minutes (+ 10.8 minutes; range, 20 to 51 minutes). The disposition of the transported patients is shown (Figure). All patients received endotracheal intubation, IV drug therapy, and defibrillation or cardioversion according to American Heart Association standards. Resuscitative efforts were discontinued in the field only after consultation with the medical control physician. Ten patients experienced the return of spontaneous circulation. The single patient surviving to discharge was a 69-year-old woman with severe asthma who had suffered a primary respiratory arrest followed by cardiac arrest (ventricular fibrillation). She was resuscitated by prehospital providers after dispatch but before the arrival of the airborne medical team.

The mean charge to the patient for aeromedical services, using charges in effect over the course of the study, was $638.00 per completed flight. This figure does not include additional ED or hospital costs. Patients whose care was terminated in the field were not billed for flight services. Presently, similar flights would result in an average patient charge of $1,676.00 per flight. DISCUSSION

Aeromedical programs have held promise for improving patient outcomes by providing advanced levels of care rapidly at the scene of illness or injury. Whether this affects outcome in rural cardiac arrest is an important question, considering the costs and risks of helicopter operations. The crucial initial factor in improving a victim's chances of surviving arrest has been shown to be the time between arrest and the initiation of BLS and ALS care; survival rates fall precipitously if BLS care is delayed more than four minutes and if ALS care, primarily defibrillation, is delayed for more than eight minutes after arrest, s The difficulties faced in bringing the most appropriate care to the victim's side in the shortest amount of time are Figure.

Disposition of cardiac arrest victims (N = 84) Efforts terminated in the field 55 (65%) Transported to ED 29 (34%) Efforts in 19the terminated (23%) ED

Admitted 10 (12%)

Table.

Primary contributing conditions Condition

No. (%1

Noneidentified Cardiac Diabetes Pulmonary Malignancy Drowning Stroke Drugs(cocaine) Anaphylaxis(beesting)

35 (42) 30 (35) 5 (6) 4 (5) 3 (4) 3 (4) 2 (2) 1 (1) 1 (1)

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Support withdrawn 4 (5%)

Efforts terminated on admission to the CCU 1 (1%)

Expired due to cardiac/respiratory insufficiency 4 (5%) Discharged alive 1 (1%)

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most evident in rural areas where the population is thinly distributed, response times of EMS units are longer than in urban or suburban areas, and ALS care may be less readily available. Nontraumatic out-of-hospital cardiac arrest has a poor prognosis; reported survival rates vary from 2% to 26%, with a trend toward higher survival rates in urban, multiple response systems.4 Survival rates in suburban/rural systems with ALS care available from ground units have been reported to range from 4% to 11%.6-s The use of aeromedical programs as part of a comprehensive system for the management of trauma is thought to improve survival. 9-n However, little is known about the benefits of aeromedical evacuation in the management of patients with acute medical illness in general and cardiac arrest in particular. One study that examined the outcome of 67 victims of traumatic cardiac arrest attended by aeromedical crews reported that no patients survived to discharge. 12 Response of the aeromedical team did not appear to affect survival in the group of patients reported here. The survival rate in this study was low even when compared with victims of arrest in similar settings. Survival among cardiac arrest victims treated by ALS providers in Durham County, North Carolina, was 4%,6 6% in York County, Pennsylvania/and 11% in patients treated in the field by paramedics in rural northeastern Minnesota. 8 Factors that may have contributed to low survival in the current study group include a large percentage of patients "found down" (41%) conceivably experiencing long delays before the initiation of care, long times to BLS (mean, 5.77 minutes) and ALS care (mean, 15.7 minutes), and the low percentage of patients receiving bystander CPR (32% of opportunities). The estimates of time to BLS and ALS care may be quite conservative and biased toward shorter times, as the documentation of "down times" and times to BLS and ALS care were more often complete in cases in which arrests were observed by bystanders or prehospital providers. These figures are illustrative of the problems associated with the provision of care to cardiac arrest patients in rural areas. These results suggest that aeromedical programs cannot be expected to augment local BLS and ALS resources for rural cardiac arrest victims. Although the aeromedical team may represent the pinnacle of prehospital sophistication and in this study was able to provide ALS care in 42% of instances in which it was otherwise unavailable, their response appears, to have been of little benefit to the patients because the primary requirement of rapid provision of care was not achieved. The mean time of 17.8

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minutes required for the aeromedical team t o reach the landing zone greatly exceeds the nominal ten-minute time frame during which the initiation of ALS care most probably would improve survival rates. In cases in which the aeromedical team constituted the only available ALS care, nearly 34 minutes elapsed on average before they arrived on scene. Aeromedical programs are an inefficient way to provide "first-line" prehospital care; they are very expensive to operate and staff and are a limited resource in most situations. Their operation imposes a small but appreciable risk for air crews and patients. Between 1978 and 1991 there were 75 accidents, for an accident rate of 3.10 accidents per 100,000 patients flown. E3,14 Augmenting local resources by increasing the chance of prompt BLS provision and defibrillation has been the thrust of many efforts to reduce mortality from out-of-hospital cardiac a r r e s t . 1-5,15-19 Increasing the local availability of BLS care through citizen CPR classes and increasing the number of first-responder units trained and equipped to provide CPR and rapid defibrillation may be the most efficient options for improving survival from cardiac arrest in the rural setting. No study patient who arrived in the ED without a spontaneous perfusing rhythm survived to hospital admission. This is in keeping with other investigators' findings that the patients most likely to respond to resuscitative efforts are those who respond quickly. 2°-22 Patients who have had access to prehospital ALS care and who have not responded have a low likelihood of responding to continued efforts in the ED, 23-25 as do those who have received prolonged BLS care (more than 45 minutes) without the benefit of ALS treatment. 24 It is important that some groups of patients be considered separately, such as those suffering from hypothermia, and that each case be considered for extenuating circumstances. 22-27 Several facets of this study require further examination to put the results in perspective. We report the experience of a single aeromedical program responding to requests in a single EMS system; other systems may have differences in the structure of response and the availability of BLS and ALS units that could change the role of an aeromedical program in that system or change the spectrum of cardiac arrest victims the system would encounter. The number of patients comprising the study group was small; a larger series of patients, probably derived from a multicenter trial, will be required to answer this question in a definitive manner. The study cohort was heterogeneous with respect to major pre-existing conditions or insults that led

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to cardiac arrest. Although the number of patients in each of these subgroups was small, it can be argued that once cardiac arrest has occurred, the initial factors influencing survival are similar across all groups and revolve around the availability and proximity of emergency care. This study did not present the outcomes of all cardiac arrest victims encountered in the EMS system during the study period. The patients selected as the study cohort were those who were still in arrest at the time the assistance of the aeromedical team was requested. Patients who were resuscitated before the request were not included; thus, the study patients may have represented a group with a particularly poor chance of survival because they either had not responded to field therapy or did not have access to ALS care in the field. Nevertheless, this group comprised a readily identifiable subset of patients, which amounted to just more than 8% of scene flights for our program in a four-year period. The availability of accurate records regarding the time periods between cardiac arrest, initiation of BLS care, and the availability of ALS care was also a limitation in accurately describing the study group. In light of the results of this study and the results of the previously cited study regarding traumatic cardiac arrest and air transport,12 the Pegasus Air Transport Program has modified its response to patients who are in cardiac arrest at the time of request, have access to ALS care, and do not appear to have suffered an insult (eg, hypothermia) that might improve their chances of survival. Dispatch of the aeromedical team is no longer automatic in these cases but is reviewed immediately by the emergency physician providing on-line medical command, who may elect to dispatch the aircraft if extenuating circumstances exist. CONCLUSION

Successful resuscitation from cardiac arrest requires the rapid initiation of BLS and ALS care. Although helicopter air transport programs offer the possibility of providing improved availability of ALS care in rural areas, their deployment in a series of 84 instances of nontraumauc cardiac arrest in a rural setting had no apparent effect on mortality. The reason for a lack of demonstrable benefit was the inability of the flight program to provide ALS care within the optimal time flame. The role of air medical programs in the setting of rural cardiac arrest may be limited to providing rapid transport of resuscitated patients or providing rapid transport in cases in which circumstances suggest an enhanced chance of recover K from cardiac arrest.

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REFERENCES 1. Eisenberg MS, Bergner L, Hallstrom A: Importance of rapid provision and implications for program planning. JAMA 1979;241:1905-1907. 2. Hunt RD, McCabe JB, Hamilton GC, et ah Influence of emergency medical services systems and prehospital defibrillation on survival of sudden cardiac death victims. Am J EmergMad 1989;7:68-82. 3. Rinke CM: Prehospital cardiopulmonary resuscitation, is it effective? JAMA 1985;253:24082412. 4. Eisenberg MS, Herwood BT, Cummins RO, et al: Cardiac arrest and resuscitation: A tale of 29 cities. Ann EmergMeal1990;19:179-186. 5. Weaver WD, Cobb LA, Hallstrom AP, et ah Factors influencing survival after out-of-hospital cardiac arrest. JACC1986;7:752-787. 6. Pressley JC, Raney MP, Wilson BH, et al: Assessment of out-of~hospital resuscitation. Am J EmergMed 1984;2:215-216. 7. Eitel DR, Walton SL, Guerci AD, et al: Out-of-hospital cardiac arrest: A six-year experience in a suburban-rural system. Ann EmergMad 1988;17:808-812. 8. Bachman JW, McDonald GS, O'Brien PC: A study of out-of-hospital cardiac arrests in northeastern Minnesota. JAMA 1986;256:477-483. 9. Moylan JA, Fitzpatrick KT, Bayer AJ, et ah Factors improving survival in multisystem trauma patients. Ann Surg1988;207:679-685. 10. Baxt WG, Moody P: The impact of a retorcraft aeromedical emergency care service on trauma mortality. JAMA 1983;249:3047-3051. 1I. Baxt WG, Moody P, Cleveland HC, et ah Hospital-based rotorcraft aeromedical emergency care services and trauma mortality: A mutticenter study. Ann EmergMad1985;14:859-864. 12. Wright SW, Dronen SC, Combs TJ, et al: Aeromedical transport of patients with posttraumatic cardiac arrest. Ann EmergMad1989;18:721-726. 13. Collett HM: Air medical accident rates. JAirMed Trans1991;10:14-15. t4. Preston M: 1991 air medical helicopter accident rates. J Air Mad Trans1992;11:14-16. t5. Lund I, Akulberg A: Cardiopulmonary resuscitation by lay people. Lancat1976;702-704. 16. Copley UP, Mantle JA, Rogers W J. et al: Improved outcome far prehospital cardioputmonary collapse with resuscitation by bystanders. Circulation1977;58:901-905. 17. Thompson RG, Hallstrom AP, Cobb LA: Bystander-initiated cardiopulmonary resuscitation in the management of ventricular fibrillation. Ann InternMad 1979;98:737-740. 18. Guzy PM, Pearce ML, Greenfield S: The survival benefit of bystander cardiopulmonary resuscitation in a paramedic served metropolitan area. Am J PublicHealth 1983;73:768-769. 19. Kowaiski R, Thompson BM, Horwitz L, et al: Bystander CPR in prehospital coarse ventricular fibrillation. Ann EmergMad 1984;13:1016q 020. 20. Aprahamian C, Thompson BM, Gruchow HW, et ah Decision making in prehospital sudden cardiac arrest. Ann EmergMad 1986;15:445-449. 21. Wolford RW, Kaplan RM, Stewart RD, et ah ALS witnessed prehospital cardiac arrest (abstractL Ann EmargMad 1988;17:410. 22. Warner LL, Hoffman JR, Baraff LJ: Prognostic significance of field response in out-of-hospital ventbcular fibrillation. Chest1985;87:22~28. 23. Kellerman AL, Staves DR, Hackman B8: In-hospital resuscitation following unsuccessful prehospitat advanced cardiac life support: "Heroic efforts" or an exercise in futility? Ann Emerg Mad 1988;17:589-594. 24. Smith JP, 8odai B]: Guidelines for discontinuing prehospital CP8 in the emergency department--A review. Ann EmergMad 1985;14:1093-1098. 25. Bonnin M J, Swor RA: Outcomes in unsuccessful field resuscitation attempts. Ann ErnergMad 1989:18:507-512. 26. Eisenber9 MS, Cummins 80: Termination of CPR in the prehospital arena {letter). Ann Emerg Med1985;14:1106-1107. 27. Kellermann AL, Hackman BB: Terminating unsuccessful advanced cardiac life support in the field (letter). Am J EmergMad 1987;5:548-549. Address for reprints: George H tindbeck, MD Division of Emergency Medicine Box 523-21, University of Virginia Hospital CMrlottesville, Virginia 22908

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