Friendly skies?

Richard L Page MDAssociate Professor of Internal MedicineDirector, Clinical Cardiac ElectrophysiologyUniversity of Texas Southwestern Medical CenterDallas, TX

Qantas installed portable semiautomatic external defibrillator devices (AEDs) in 1991 on all its international Boeing 747 and 767 aircraft and at major Qantas airport terminals.

In the 65 months after these devices were installed, 46 incidents of cardiac arrest were treated, 27 in aircraft.

27 passengers went into cardiac arrest and were treated with the AED on board the aircraft. 6 of the 27 went into ventricular fibrillation (VF). The defibrillator worked in 5 of the 6. Two of them survived, apparently saved by the defibrillators.

19 cases of cardiac arrest were reported at the airports; 17 of those went into VF and defibrillation worked on all 17.

In-flight cardiac careQantas success story

By July 1997, AEDs were deployed on all international flights and certain domestic over-water routes; main flight attendants or pursers were trained to use the defibrillators in the event of an in-flight medical emergency.

By the end of 1998, all 649 American’s jet aircraft had defibrillators on board, and all 24,000 flight attendants had been trained to use the AED. 

In-flight cardiac careAmerican Airlines follows Qantas’s lead

FDA-designated indications for AED placement

• full loss of consciousness

• an absence of breathing, or

• absence of pulse

FDA guidelinesAED indications

Physicians present can request that an AED be used as a monitor because the device has a monitor screen. If the device is used as a monitor, it can then be placed outside of the typical or more strict indications.

In 69% of cases a physician was present.

In 42% of cases loss of consciousness was documented.

Rhythms associated with death were seen in 28 of the 204 patients

• 14 of the 28 had agonal rhythm

VF was documented in 14 of the 204 patients

• shock was administered in 13 patients

• relatives of 1 terminally ill patient refused treatment

In 2 cases where shock was administered, the EKG recording was not available for analysis, but it is likely that VF was present.

Of the 15 patients who received shock for VF, 6 (40%) were discharged from hospital to lead full functional lives.

American Airlines study204 cases of AED use

Richard L Page MD, presented at the 21st Annual Scientific Sessions of the North American Society of Pacing and Electrophysiology (NASPE), Washington, DC

A 40% resuscitation from VF compares favorably with any EMS system.

In many cases, the device was placed on passengers with fatal rhythms, and often without full loss of consciousness; but in no case did the AED recommend or deliver shock inappropriately.

Even in the isolated environment of the aircraft the device worked well for VF and was safe even if used when VF was not present.

American Airlines studyAED effective and safe

Using the AEDIdiot-proof technology

Remove the adhesive backing and place the 2 electrical patches (not paddles) on the bare chest.

Turn the device on.

The device reads the heart rhythm and gives both a verbal and a display recommendation to shock if ventricular fibrillation (VF) is detected.

If a shock is recommended, the person operating the AED will be instructed to stand back and push the flashing red button to deliver the shock.

The AED will not deliver a shock if it does not detect VF.

After the shock, the device re-analyses the electrograms and determines whether another shock is recommended.

In 204 AED uses, the device never inaccurately recommended a shock, and never failed to detect VF that required a shock.

In most uses, after tracking the heart rhythm, the device determined no shock was required.

All but 1 patient was shocked out of VF with a single shock.

The only case that didn't convert with a single shock converted with a second shock.

American Airlines studyReliable shocks

Robert C Kowal MD, presented at the 21st Annual Scientific Sessions of the North American Society of Pacing and Electrophysiology (NASPE), Washington, DC

Shockable rhythmsDifferences between airlines

AED can terminate VF, but survival is effected by the condition of the heart and the time the patient has been down.

A flat line or agonal rhythm may imply that the patient was in arrest long before it was recognized or that the heart is so sick that it can't be resuscitated; patients who persistently came out in an agonal rhythm died.

American Airlines had more shockable rhythms than Qantas, possibly because of the duration of the flights. On the longer Qantas flights, where more people were found in agonal or slow rhythms, it is more likely that passengers are assumed to be asleep, when they may be dead.

This lack of recognition may account for the higher percentage of slow heart rhythms seen on airlines than in public places where people are moving around.

With the use of a mock cardiac arrest scenario, AED use by 15 6th grade children was compared with that of 22 emergency medical technicians (EMTs) or paramedics.

The primary endpoint was time from entry at the cardiac arrest scene to delivery of the shock into simulated ventricular fibrillation.

The secondary endpoint was appropriateness of pad placement.

All performances were videotaped to assess safety of use and compliance with AED prompts to remain clear of the mannequin during shock delivery.

Gundry JW, et al. Circulation 1999;100:1703-1707

Children vs EMTsStudy design

Electrode pad placement was appropriate for all subjects.

All remained clear of the patient during shock delivery.

The speed of AED use by untrained children was only modestly slower than that of professionals.

The difference between the groups is surprisingly small, considering that the children were untutored first-time users.

These findings suggest that widespread use of AEDs will require only modest training.

Gundry JW, et al. Circulation 1999;100:1703-1707

Children vs EMTsStudy results and conclusions

Mean time to defibrillation(range), seconds

Children EMTs/paramedics p value

90 ± 14 (69–111) 67 ± 10 (50–87) <0.0001

Every day more than 600 Americans died from cardiac arrest.

Chance of survival is reduced by 10% for every minute of waiting.

All too frequently, by the time the paramedics arrive and defibrillation is performed it is too late to save the patient.

Any reasonable individual can probably obtain enough information from the AED instructions to administer treatment, which would be better than waiting for emergency assistance.

According to estimates by the American Heart Association, 30% of Americans suffering from cardiac arrest could be saved by immediate treatment with AEDs.

Survival statistics Response time key to survival

The House of Representatives passed a bill in 1999 that directs the Department of Health and Human Services to develop guidelines for installing AEDs in federal buildings, and granting legal immunity to those who use them.

President Clinton proposed a new Federal Aviation Administration (FAA) rule that would require all commercial airplanes with at least 1 flight attendant to carry an AED on international and domestic flights.

Cardiac Arrest Survival Act

http://thomas.loc.gov/cgi-bin/bdquery/z?d106:h.r.02498:

The Cardiac Arrest Survival Act of 1999 provides that any person who provides emergency medical care through the use of a defibrillator, any person who maintained, tested, or provided training in the use of the device, any physician who provided medical oversight of the device, and the person who acquired the device (if specified conditions have been met) is immune from civil liability for any personal injury or wrongful death resulting from the provision of such care, unless the person engaged in gross negligence or willful or wanton misconduct under the applicable circumstances.

Immunity for AED users

http://thomas.loc.gov/cgi-bin/bdquery/z?d106:h.r.02498:

Chest compression vs CPRA Seattle study conducted between 1989 and 1998 looked at 520 episodes of cardiac arrest.

In a randomized manner, telephone dispatchers gave bystanders at the scene of apparent cardiac arrest instructions in either chest compression alone or chest compression plus mouth-to-mouth ventilation.

Complete instructions were delivered in 62% of episodes for the group receiving chest compression plus mouth-to-mouth ventilation and in 81% of episodes for the group receiving chest compression alone.

Instructions for compression required 1.4 minutes less to complete than instructions for compression plus mouth-to-mouth ventilation.

Time to response by emergency services averaged 4 minutes, and all units were equipped with automated defibrillators.

Hallstrom A, et al. N Engl J Med 2000; 342:1546-1553

Results

Chestcompressio

n only (n=241)

StandardCPR

(n=279)

p valu

eDischarged from hospital alive 14.6% 10.4% 0.18Admitted to hospital 34.1% 40.2% 0.15

The rates were higher in the group receiving instructions on chest compression alone, although the differences were not statistically significant. Outcome was similar for both types of instructions, but chest compression alone may be the preferred approach for bystanders inexperienced in CPR.

Hallstrom A, et al. N Engl J Med 2000; 342:1546-1553

Chest compression vs CPR