A patient you are caring for in the ED collapses. The nurses check pulses. One feels a pulse, one does not. Do you start CPR?
Studies do show that “feeling a pulse” does not mean a pulse is there. Many of these studies have significant limitations but overall they all seem to say the same thing. People feel pulses that are not there approximately 10% of the time.(Eberle Resuscitation 1996) One study in infants recommended using auscultation as more accurate than palpation.(Inagawa Paediatr Anaesth 2003)
We use unresponsiveness and apnea as adjuncts to recognize cardiac arrest. Apnea needs to be interpreted properly. An agonal gasping respiration raises the concern for cardiac arrest, rather than arguing against it. And respirations can continue for up to 3 minutes after ventricular fibrillation, so don’t be too rigid in using respiration to rule out the need for CPR.(Menegazzi AEM 1995)
How do we diagnose cardiac arrest? First, they have to be unconscious. Next, there needs to be some finding that indicates lack of perfusion. This can be pulselessness or apnea/gasping. Early on there is often doubt, but jump on the chest and start CPR if you don’t feel clear and obvious pulses.
Take Home Points:
-The pulse examination is not 100% sensitive or specific for cardiac arrest
-Given that we have to make decisions with imperfect information, it is better to err on the side of starting CPR
-Apnea is not 100% sensitive either, as respiration can continue for 1-3 minutes