Assessing Vitals: Not As Easy As Pushing A Button

Whenever evaluating a new patient, I always start of my objective portion with a pulse and blood pressure assessment. I've always been leery of using machines to do this due to the frequency with which they provide inaccurate findings. This became even more evident a couple weeks ago. I was assessing a patient's pulse when I noted an abnormal rate. The rhythm was 3 consistent pulses followed by a rest. This pattern continued. I had another PT assess the patient's pulse as well to confirm my findings. The patient denied any previous cardiac issues. Due to the irregularities, I advised the patient to return to his PCP for further assessment and likely cardiologist referral. About a week later, the patient phoned in and said he was going to a cardiologist and would start PT once everything was taken care of.

The reason I bring this up is because a machine does not typically pick this up. When relying on blood pressure machines or pulse-oximeters for heart rate, we often end up just getting the bpm. The actual rhythm is missed. This patient showed no other signs of cardiovascular disease. I'm not saying you shouldn't use machines, but be sure to assess for rhythm and intensity of the pulse as well.

Expected ECG Findings

The easiest way to explain the heart rhythm is to refer back to an electrocardiogram (ECG - as depicted below). For review, we will go over the basics of an ECG first:

-P Wave: depolarization of atria (starting at the SA node, then spreading out to the atria)
-PR Interval: time it takes for the electrical pulse to get from the SA node to the AV node)
-QRS Complex: depolarization of ventricles (starting at the AV node; re-polarization of atria hidden here)
-T Wave: re-polarization of ventricles

This patient in particular, as you recall, had 3 pulses followed by a pause. This likely signifies a Second Degree AV Block: Mobitz Type I (Wenckebach). This would be depicted at a slowly increasing PR interval, before a lack of QRS complex occurs. The cycle then restarts. Basically this means the signal from the SA node to the AV node slows until it doesn't make it through to initiate ventricular contraction, before the next SA node initiates again to restart the cycle.

If you've ever struggled with interpretting ECG's, I recommend reading this book by Dale Dubin. It provides a step-by-step understanding and asssessment of ECG's along with the associated pathologies, at an MD level. It is an excellent source for reviewing for a CardioPulm course or preparing for the Cardiovascular section of the boards!

-Chris