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Tuesday, March 29, 2011

Cardiac Arrest

An elderly man collapses in an airport. A physician who witnesses the collapse checks his pulse and respirations and finds neither.

Which of the following is the most important determinant for short-term survival in this patient?
A Time to cardiopulmonary resuscitation
B Time to defibrillation
C Time to intubation
D Time to transport to the hospital

Key Point
Time to defibrillation is the most important determinant of survival in cardiac arrest.

Answer and Critique (Correct Answer = B)

Because most adults who suffer cardiac arrest initially demonstrate ventricular arrhythmias, time to defibrillation is the most important determinant of survival. Defibrillation within the first 4 minutes of ventricular fibrillation results in high survival rates, and the availability of automated external defibrillators in many public settings such as airports has made early defibrillation possible. Each minute that defibrillation is delayed reduces the chance of eventual hospital discharge by 8% to 10%.

Bystander cardiopulmonary resuscitation has been shown to improve survival, but prompt defibrillation is more important. Time to transport to the hospital does not correlate with survival—it is restoration of normal blood flow that is critical. Intubation helps provide adequate oxygenation but also is not as important as restoration of a normal cardiac rhythm.

1. Ali B, Zafari AM. Narrative review: cardiopulmonary resuscitation and emergency cardiovascular care: review of the current guidelines. Ann Intern Med. 2007;147:171-9. [PMID: 17679705]

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