Final answer:
The preferred method of assessing heart rate during CPR is by using an ECG, as it provides an accurate depiction of the heart's electrical activity and can indicate return of spontaneous circulation.
Step-by-step explanation:
The preferred method for assessing heart rate during chest compressions is through the use of an ECG or electrocardiogram. During cardiopulmonary resuscitation (CPR), it is crucial to monitor the heart's activity accurately, and ECG provides real-time electrical activity tracking, which helps to determine if the heart starts to show spontaneous rhythms which is indicative of successful resuscitation.
In emergency settings, it can be challenging to auscultate or palpate for a pulse because chest compressions might create pulsations that mimic a heartbeat, leading to misinterpretation. Pulse oximetry is also not reliable during CPR due to poor peripheral blood flow. Therefore, ECG monitoring is superior during active resuscitation efforts.