Difference between diagnostic and monitoring monitor modes

[NPO]

So I know that just looking at Lead II or III or any lead for that matter on the monitor is usually considered nondiagnostic, if it's not in 12 lead mode. And I know that the 12-lead mode uses different filters to reveal things that monitoring mode might otherwise cover-up.

But how come (assuming no gain is applied) sometimes the monitoring mode shows significantly more ST elevation than the 12 lead? I've had multiple times when you look at the monitor, or even a printed rhythm strip, and think you've got a STEMI, but no matter what you do, you can't get it to show up on the EKG. What gives?

Case in point, just my most recent that got me thinking...

I looked down and saw large STE on leads II, and III on the monitor. The patient had a significant cardiac history and was very symptomatic for ACS. I did an EKG and the and the STE was negligible and hardly discernable. What gives?

I'm using an LP15, but I've also had this happen on Zolls.

Side bar thoughts on the EKG are also welcomed.

The STE was obvious on a printed strip, but the digital one is attached anyway.

 

[StCEMT]

I've noticed it on zolls. If I go to the 12 lead screen it seems to get rid of the distortion. I never fully trust it when I see it pop up in the standard screen, I just do the 12 as a CYA if it looks funny.

That being said, I have no idea what causes it, I just know when to verify.

 

[mgr22]

See the ".05-150 Hz" frequency at the lower left of the 12-lead? Compare that to the much narrower range of "monitor-mode" tracings on 3-lead EKGs -- e.g., 1-30 Hz -- and you have your answer for why ST segments appear to vary. In general, the 12-lead tracings are accurate and the 3-lead tracings may not be. It's not uncommon for a monitor-mode EKG to show ST deflection opposite to what you'd see in "diagnostic mode" (i.e. 12-lead quality). It has to do more with restrictions to low-frequency response than high frequency.

Not sure how much more of an explanation you want. I have some literature on this if you want to email me at [removed]

 

[NomadicMedic]

I was just about to write this almost exact same post. Well done.

 

[Summit]

SUMMIT'S QUICK GUIDE TO EKG FILTERS:


Ever wonder why the monitor shows ST segment changes that aren’t there on the 12 lead?

Usually it is the filtering mode (and a bit of electrode placement and patient position). Filtering helps us with false alarms and artifact caused by patient movement, tremors, and other sources of interference such as signal leakage from electrical lines and devices. However, the filtering can alter, falsely create, or eliminate EKG features we need to see. One of the principle ways we see filtering is that it will mask ST segment changes or create ST segment elevation/depression where this is none.

What do the filter modes do?

Diag – (almost) no filtering

Use continuously: to allow continuous ST segment monitoring, on immobile or paralyzed patients

Use intermittently: to view unaltered ST segments, check for U waves, or closely evaluate QRS morphology such as R wave notching.

WARNING: Very sensitive to patient movement which can lead to false alarms or unreadable telemetry.


Ext Filter –Almost diagnostic but filters baseline wander

When to use: on patients needing close monitoring of QRS morphology but have a wandering baseline.

WARNING: ST segment cannot be evaluated in this mode. Very sensitive to patient movement which can lead to false alarms or unreadable telemetry.


Monitor –Filters out motion artifact and baseline wander

When to use: Most of the time on mobile patients

WARNING: ST segment cannot be evaluated in this mode.


Filter – Maximum filtering

When to use: Patients with a tremor or severe artifact

WARNING: May HEAVILY alter QRS morphology. ST segment cannot be evaluated in this mode.

 

[Brandon O]

Christopher Watford had the best explanation of the artifact here: http://www.ems12lead.com/2014/03/10/understanding-ecg-filtering/

 

[Summit]

Nice tech article Brandon I love it!

(My post above I originally wrote as a quick education regarding hospital telemetry monitors)