Normal QRS duration

NPO

Forum Deputy Chief
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I have always used and been told .08-.12 sec is normal for QRS duration, however an instructor just told us .06-.10 which I've never heard, and after looking in the book, it says .08-.10.

What do you use?
I'll probably be sticking to .08-.12.
I doubt it makes much difference, but I'm curious why there are so many variations on what I believed to be such a standard.
 

TomB

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A normal QRS duration is in the 80-100 ms range. It is considered prolonged between 100-119 ms but not "wide" for the purposes of identifying complete bundle branch blocks and ventricular rhythms.
 

MackTheKnife

BSN, RN-BC, EMT-P, TCRN, CEN
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Others teach 0.04-0.12
 

18G

Paramedic
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During school, I was always taught <120ms is a normal QRS duration. While writing an article on TCA toxicity recently, I found out that the normal QRS duration is, in fact, <100ms. The treatment threshold for treating TCA toxicity is a widened QRS measured at >100ms. Multiple sources state the normal QRS as 100ms. It was also stated by multiple sources that some adults have a normal QRS up to 120ms. But when it comes to making a treatment decision with sodium bicarb in TCA toxicity, a QRS of >100ms is very important as this represents cardiotoxicity.
 
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