Sudden cardiac death is responsible for ≈300 000 to 400 000 deaths yearly in the United States, depending on the definition used. When the definition is restricted to death occurring <1 hour from the onset of symptoms, patients included have a >90% incidence of an arrhythmic death.1
Sudden cardiac death is commonly the initial manifestation of coronary heart disease. It accounts for 50% of the mortality from cardiovascular disease, which remains the main cause of death in this country.2 Sudden cardiac death rates in developed countries outside the United States are similar. Approximately 75% of cardiac arrests occur at home, and about two thirds are witnessed. The chances of surviving sudden cardiac arrest are <10%, with most persons dying before reaching a hospital. Those people who do survive a cardiac arrest have a good chance of living many more years; ≈80% are alive at 1 year, and as many as 57% are alive at 5 years.
Arrhythmias in Sudden Cardiac Death
Ventricular fibrillation is the initial recorded rhythm in 40% to 70% of patients who have cardiac arrest, depending on the patient population and the time to first recording.3 4 Sustained ventricular tachycardia is the first rhythm documented in fewer than 2% of sudden death victims, but it is unknown how often it precedes and precipitates ventricular fibrillation. In 157 patients who were wearing an ambulatory ECG recorder at the time of their cardiac arrest, primary ventricular fibrillation was documented in 8%, ventricular tachycardia degenerating into ventricular fibrillation in 62%, and torsades de pointes in 13% of patients.5
Electromechanical dissociation and asystole are found in 30% to 50% of cardiac arrest patients, and their occurrence usually parallels the time interval from collapse to first monitoring of the rhythm, suggesting that it is a later manifestation of cardiac arrest.3 4 Not surprisingly, it is a more common finding in persons with unwitnessed cardiac arrests.
Public Access Defibrillation
The most important determinant of successful cardiopulmonary resuscitation is the time interval from cardiovascular collapse to initial intervention. Because most patients are found to be in ventricular fibrillation, the time from onset to defibrillation is the key element in the acute management of the cardiac arrest victim. The chance of survival decreases 7% to 10% for each minute that defibrillation is delayed. The importance of early intervention is reflected in the “chain of survival” concept of emergency cardiac care systems: early access, early cardiopulmonary resuscitation, early defibrillation, and early advanced cardiac life support.6
Because early defibrillation appears to be the most important treatment in the chain of survival, in 1991 the American Heart Association challenged manufacturers to develop simple, low-cost automatic defibrillators for use by targeted groups and where large numbers of people congregate.7 At the AHA Public Access Defibrillation Conference of 1994, it was further recommended that an enhanced defibrillation strategy be extended to include defibrillation by minimally trained members of the public.8 Since then, considerable advances have occurred, and several manufacturers have developed small, lightweight, simple semiautomatic external defibrillators (AEDs) for use by the public.9 10 11 12
A second Public Access Defibrillation Conference entitled “Strengthening the Chain of Survival” was recently held by the American Heart Association in Washington, DC, from April 17 through 19, 1997; it was chaired by Dr Myron L. Weisfeldt. This conference addressed the present status of emergency medical services, the current technology of AEDs and optimal AED waveforms, training curricula for targeted responders in the use of AEDs, a clinical trial to evaluate public access defibrillation, regulatory considerations, and three levels of public access defibrillation (P.A. Bowser, coordinator, AHA Automatic External Defibrillation Task Force, personal communication). Level 1 applies to targeted, nontraditional first-responder defibrillation and includes defibrillation efforts by police and highway patrol personnel, lifeguards, security personnel, and airline flight attendants.
Sudden Cardiac Death Among Airline Passengers
The number of lives lost due to cardiac arrest in commercial aircraft each year has been estimated to be as high as 1000 per year in International Airlines Transport Association (IATA) carriers.13 14 15 The incidence of sudden cardiac death in airplane passengers has likely been underreported due to the lack of mandatory reporting procedures.
The need for better data was underscored in a Chicago Tribune special report, “Code Blue: Survival in the Sky,” published on June 30, 1996.14 Based on available data from foreign and US airlines, the Chicago Tribune estimated the number of passenger deaths aboard US carriers to be between 114 and 316 a year, not including sick passengers who died after being taken from the airplane. Most of the latter deaths were also likely due to cardiac arrest. This report also compared the relatively few drugs and scarcity of other medical equipment available aboard US airlines with the more extensive medical kits available on other international airlines.
Few airlines have equipped some or all of their aircraft with AEDs and trained selected aircraft personnel in the use of AEDs for the treatment of ventricular defibrillation, the usual initial arrhythmia in patients with sudden cardiac death; these few airlines include Qantas, Virgin Atlantic, and Air Zimbabwe, the latter of which is equipped with AEDs only on aircraft bound for London or Frankfort. In October 1996, the US Food and Drug Administration approved the use of AEDs for commercial aircraft. Recently, American Airlines bought 300 AEDs for use on “over water” aircraft and began an airline cardiac arrest program similar to that first initiated by Qantas.16 Hong Kong–based Cathay Pacific Airlines plans to equip all of its 60 aircraft with AEDs in the near future.
In the past, most US airline management believed that a fast landing is “the best thing for the patient” who is severely ill. This makes no sense for victims of sudden cardiac death considering that the time to defibrillation is the main predictor of a successful outcome in patients with sudden cardiac arrest and that 10% fewer patients will survive for each minute of delay in initiating electrical shock when ventricular defibrillation occurs. Diversion is an unsatisfactory alternative for patients with cardiac arrest because even under ideal conditions, an emergency landing from cruising altitude takes ≥20 minutes—longer if weather, air traffic, and other factors are less than perfect—and 20 minutes is too long to wait for a defibrillator.
The Qantas Cardiac Arrest Program
In this issue of Circulation, O’Rourke (no relation to this author) et al13 report the first 65 months’ experience of the Qantas Airline Cardiac Arrest Program. AEDs were installed in the major international Australian terminals and in each of the 55 aircraft by August 1992, and all flight service directors were trained to operate the device and supervise the management of cardiac arrest. Approximately 4000 cabin crew were trained in the rapid initiation of cardiopulmonary resuscitation for the victim of sudden cardiac death. Further supervision was available through volunteer physician responders en route on Qantas aircraft or remotely by Qantas medical staff in Sydney. Recently, each aircraft was supplied with an extensive Qantas medical kit that contains all the facilities for advanced cardiac life support by traveling medical practitioners who volunteer and wish to use them.
During the study period, there were 27 episodes of sudden death on aircraft and 19 in the major Australian international terminals attended by Qantas staff. The monitor defibrillator was used on all 46 of these persons and in 63 other acutely ill persons for monitoring purposes. As might be anticipated, all 19 episodes of cardiac arrest occurring in terminals were witnessed compared with just 16 of the 27 (59%) occurring on aircraft. In 8 cases, passengers could not be aroused from sleep, and 7 of these were found to be in asystole. Not surprisingly, 17 of the 19 patients (89%) with cardiac arrest occurring in terminals were found to be in ventricular fibrillation compared with only 6 of the 27 airborne passengers with cardiac arrest; each of these 6 had a witnessed arrest. Successful defibrillation was accomplished in 5 of the 6 airborne patients with ventricular fibrillation, and the aircraft was diverted expeditiously to its destination. Two of the 6 patients were long-term survivors (≥2 years), with no residual neurological impairment.
Defibrillation was initially successful in 16 patients with ventricular fibrillation in terminals, and 4 of the l7 (24%) were long-term survivors. Thus, 23 of the total number of 46 persons with cardiac arrest were found to be in ventricular fibrillation. It is highly likely that the others were initially in ventricular fibrillation that degenerated into asystole.
The report by O’Rourke and associates indicates the importance of having AEDs available in airport terminals for the early ventricular defibrillation of patients who have cardiac arrest while visiting the terminals or while passengers in transit. The greater success rate in the treatment of victims of sudden death in airline terminals, where they are frequently witnessed events and there is a shorter time interval to defibrillation compared with cardiopulmonary resuscitation attempts in airborne passengers, is extremely important. A strong case can be made for requiring the presence of an AED and other medical equipment necessary for successful cardiopulmonary resuscitation in all major airline terminals based on the experience of the Qantas Airline Cardiac Arrest Program.
In the Qantas Airline Cardiac Arrest Program, the available monitor-defibrillator device functioned well, and shocks were delivered appropriately to all patients with ventricular fibrillation and to none with sinus rhythm, idioventricular rhythm, or asystole. In response to the Public Access Defibrillation initiative of the American Heart Association, several manufacturers have developed smaller, lightweight simple defibrillators for use by the public, and the number and type of available devices are rapidly evolving. In the future, the price, weight, and complexity of these devices will likely continue to decrease; the current much reduced price is $3000 to $4000 for each AED.
The cost of supplying each aircraft and terminal with AEDs, of maintaining the equipment, and of providing additional medical supplies for advanced life support after defibrillation has been an obstacle to the more widespread use of AEDs on IATA. Additional expense also is required to train aircraft personnel in the use of AED and in maintaining that expertise. However, as indicated by the Qantas Cardiac Arrest Program experience, the monies saved by not diverting aircraft for the care of victims of sudden death who were pulseless and had no treatable arrhythmia could amount to many millions of dollars.
Also, based on the Federal Aviation Administration current valuation of $2.7 million for each human life, it has been estimated that the American Airlines AED program need save only one or two lives over the next 5 years to justify the cost of installing and maintaining AEDs and providing the expanded medical kits. The added cost per passenger would be less than 2¢ per flight over the same 5-year period.17 This certainly is an inexpensive approach to a major problem when one considers the airport tax used at many airline terminals throughout the world.
On May 16, 1997, the Honorable Barbara Kennelly of Connecticut introduced legislation to promote greater safety in commercial aviation with the introduction of the Airline Passenger Safety Act (HR 1670). This legislation would require commercial flights to carry adequate medical supplies and equipment to deal with in-flight medical emergencies. This bill would require air carriers to establish steps to be taken in the event of an emergency. It would also require airlines to carry AEDs and require each member of the flight crew to be trained in cardiopulmonary resuscitation and the use of an AED. This new legislation would also mandate that the air carriers describe what happened and what actions were taken to assist the passenger in the event of an in-flight medical emergency and report the incident to the Secretary of Transportation so the public can be fully aware of the number of in-flight medical emergencies that occur each day. Also included is a “Good Samaritan” provision that exempts from liability trained airline staff, physicians, and other medical personnel who step forward to offer assistance during an in-flight medical emergency. As previously stated, the US Food and Drug Administration has already approved the use of AEDs for commercial aircraft (as of fall 1996).
As the number of aircraft equipped with AEDs increases, the group of airline flight attendants trained in first-responder defibrillation increases, and the medical supplies necessary for advanced life support are provided on more aircraft, many more airborne victims of sudden cardiac death will be defibrillated successfully. Thus, “Saving Lives in the Sky” will become a major airline achievement rather than just an unusual experience reported by the few airlines currently involved in cardiac arrest programs.
The author wishes to acknowledge Richard Kerber, MD (Division of Cardiology, University of Iowa) for his constructive criticism.
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
- Copyright © 1997 by American Heart Association
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