Pauses in chest compressions are known to be detrimental to survival in cardiac arrest, so much so that the 2010 American Heart Association (AHA) emphasize high-quality compressions while minimizing interruptions. There have been some studies that now advocate for continuous chest compressions during a defibrillation shock. There have been substantial changes to external defibrillation technology including:
Biphasic shocks with real-time impedance monitoring to reduce peak voltages
Paddles being replaced by adhesive pre-gelled electrodes
Enhancement in ECG filtering permitting rhythm monitoring during chest compressions.
So the mantra of "hard and fast" may be true when it comes to CPR, but the real question now becomes, should we be continuing CPR during defibrillation?
Recently, I have been asked by several students at my home institution (UTHSC at San Antonio) to help them understand bundle branch blocks. This is different than some of my usual posts because it is meant to be more educational than evidence based. So here we go. The normal conduction system of the healthy heart is shown to the right. If there is a delay or block in the left or right bundle, depolarization will take longer to occur. Therefore we get a widened QRS (>0.12 sec or >3 small boxes).
ECG interpretation is one of the most important skills to master as an emergency physician, and its interpretation can be very complex and frustrating. ECG manifestations can be very subtle, and sometimes the earliest and only ECG change seen will be reciprocal changes alone. To further complicate this, many patients have the atypical symptoms of nausea/vomiting, weakness, or shortness of breath and not chest pain.
In Advanced Trauma Life Support (ATLS), we learned that a carotid, femoral, and radial pulse correlates to a certain systolic blood pressure (SBP) in hypotensive trauma patients. Specifically ATLS stated: