Case Studies in Sudden Cardiac Arrest

Gerald W. Smetana, MD

Disclosures

May 05, 2003

In This Article

Case #2

A 77-year-old woman presented to the ED after a witnessed cardiac arrest at the local airport. She was widowed and had lived alone in a senior apartment complex for the past 5 years. The nearest hospital was 1 mile away and EMTs were based at the same institution. She was retired and had worked as an attorney until age 68.

Past medical history included hypertension, elevated cholesterol, and obstructive sleep apnea. She wore CPAP nightly, but continued to experience daytime somnolence. She has smoked half a pack of cigarettes a day for the past 40 years, and drank no alcohol. She had a chronic daily cough. She walked 2 miles daily without dyspnea or other limitation. She had never experienced chest pain, palpitations, presyncope, or syncope and had no known history of CAD. Current medications included nifedipine 30 mg orally once daily and simvastatin 20 mg orally once daily.

On the day of presentation, she was at the airport waiting for a flight to visit her grandchildren. Bystanders at the airport reported that they saw her suddenly drop to the floor while walking in the terminal. At a subsequent interview, the first lay responder described that the woman collapsed abruptly without any vocalization and was found to be unresponsive, pulseless, and without respirations. This lay responder, along with another bystander who was a nurse without formal training in advanced resuscitation, began CPR. This particular airport had recently instituted a policy of providing public access defibrillators in the terminals. Bystanders notified airport security staff who brought a defibrillator to the scene and also called the EMTs.

Question: What percentage of SCA occurs outside of the hospital?

The most recent (1999) US mortality data, compiled from death certificates, showed that 728,743 cardiac disease deaths occurred in the United States. Of these, 63.4% of deaths were a result of SCA, 46.9% of which occurred out-of-hospital.

The nurse bystander, who had no training in defibrillator use, applied the defibrillator pads approximately 4 minutes after the patient's collapse. The defibrillator did not identify a shockable rhythm and therefore no shock was delivered. Subsequent interrogation of the public access defibrillator device indicated that the initial rhythm was a junctional bradycardia. Trained emergency medical personnel arrived 8 minutes after the collapse.

Question: In what proportion of cases of sudden cardiac arrest is a shockable rhythm present?

Ventricular fibrillation or pulseless ventricular tachycardia, rhythms that commonly occur following MI, are the rhythms most often detected immediately following SCA.[1] Both of these rhythms can respond to shock. Although reported rates of shockable rhythms have varied, the majority of rhythms found have been ventricular fibrillation. In a recent study in which public access defibrillators were used shortly after SCA, ventricular fibrillation was present in 18 of 21 victims of SCA.[8]

But the exact proportion of individuals experiencing SCA who present with a shockable rhythm is unknown, since rhythms typically change as the cardiac arrest progresses over time, and because time from collapse to rescue attempt varies among victims. For example, ventricular fibrillation could be the presenting rhythm but asystole may be present at the time of an initial rescue attempt 10 minutes following arrest.

Question: How likely are untrained Good Samaritans to correctly use a public access defibrillator in an emergency situation?

Data documenting successful use of defibrillators by untrained lay individuals has emerged from studies of public access defibrillator rescue. To date, the most compelling evidence of successful bystander use comes from a study conducted at 3 Chicago area airports.[8] During a 2-year time period, 14 people were defibrillated following SCA by Good Samaritans. Although defibrillation was done within the first 5 minutes of arrest, 3 people died. But 11 were successfully resuscitated and were alive at 1 year after arrest. Six of the 11 successful rescuers did not have training in use of defibrillators (although 3 of 6 had a medical degree).

All 50 US states have Good Samaritan legislation that protects lay rescuers from any liability associated with public defibrillator use.[21] In addition, recent national legislation requires the placement of defibrillators in Federal buildings and on commercial airliners.[22]

At the time the EMTs arrived, they found the patient to be unresponsive to voice and painful stimulus, pulseless, and apneic.

The initial electrocardiogram in the field revealed asystole.

EMTs continued CPR and established phone contact with the ED while en route to the hospital. They intubated the patient in the field and began advanced cardiac life support. The patient was briefly transcutaneously paced, then EMTs administered atropine 1 mg IV and epinephrine 1 mg IV, with restoration of sinus rhythm and a palpable pulse. Upon arrival to the emergency department, a thready pulse was palpable, but there were no spontaneous respirations. Her first electrocardiogram in the emergency department revealed sinus tachycardia.

After admission to the coronary care unit, blood pressure stabilized but the patient remained ventilator-dependent. A temporary pacing lead was placed. Telemetry demonstrated sporadic complete heart block with no underlying escape rhythm. Serial cardiac enzymes did not demonstrate evidence of MI. Despite successful hemodynamic resuscitation, the patient's neurologic status did not recover. At day 3 she did not respond to voice or painful stimulus, and had no spontaneous respirations while intubated. At a family meeting with the treating physicians, the patient's children elected to withdraw support. The patient died the following day. There was no postmortem examination.

Question: Could minimal training of security officers or other airport personnel in the use of portable defibrillators have increased the likelihood of a favorable outcome in this case?

It most likely would not have made a difference in this case if the rescuer had been trained in CPR, including use of a defibrillator. The most significant factor related to survival for this patient was that she did not have a rhythm following SCA that would potentially respond to shock. However, it is recommended that all personnel working in public areas where defibrillators are available be trained to use the device.

Questions: What is the cost of a home defibrillator? Given 300,000 sudden cardiac deaths per year, how much would have to be spent in total to prevent some of these deaths?

The cost of a home defibrillator is around $2300. It is not considered durable medical equipment and thus is not reimbursable by insurance. As a rough approximation, 80% of SCA occurs at home. If we assume that one half of these are witnessed, then opportunities could potentially exist for home defibrillation in up to 40% of all patients who sustain SCA. While data are limited, if we assume that a shockable rhythm would exist in 25% of home SCA cases,[23,24] then universal availability of home defibrillators could lead to potential delivery of a shock to 10% of all patients who sustain a SCA. If 50% of these patients survived to hospital discharge with no neurologic impairment, then 5% of all patients undergoing SCA would have this good result (in addition to those with a favorable outcome after arrest outside of the home such as in a hospital setting, and those who have a favorable result after resuscitation by EMTs or other trained responders). These estimates are, of course, imprecise due to the limited available data.

If home defibrillator use was restricted to only those patients with known CAD, the societal costs would be less, but this technology would not benefit the approximately 50% of SCA victims for whom SCA was the first clinical manifestation of heart disease.

At the current time, the cost of purchasing a home defibrillator is not covered by insurance. Therefore, the decision to purchase a unit for home use is ultimately an individual decision, based on desire and financial resources. Many individuals may consider owning a home defibrillator to be of benefit for themselves and for others living in or visiting in their home, even if they correctly perceive their own risk for SCA to be low.

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