A-line--confusion about damping, ringing, and natural frequency

[Honeeplz3]

Hello, I'm doing a little reading and really confused about damping and ringing and wanted to see if anyone can clear up my confusion.

1. I originally thought ringing was synonymous with underdamping, is this true?
2. I understand that ringing is the overlapping of natural frequency signals and biological signals. Where you get a decrease in natural frequency (caused by long, narrow tubing, multiple stock cocks and micro air bubbles) and increase in biological signals (increase HR, BP, contractility).

HOWEVER, the damping coefficient is proportional to (viscosity X length X density)/(diameter X stiffness X density).
In other words, underdamping is caused by short, wide and stiff tubing.

The causes of ringing and damping seem to contradict each other. That is what is most confusing me, if in fact they are synonymous.

I guess I'm confused how ringing, damping and natural frequency the transducer system all relate to one another.

Help me.

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[Timeoutofmind]

Hello, I'm doing a little reading and really confused about damping and ringing and wanted to see if anyone can clear up my confusion.

1. I originally thought ringing was synonymous with underdamping, is this true?
2. I understand that ringing is the overlapping of natural frequency signals and biological signals. Where you get a decrease in natural frequency (caused by long, narrow tubing, multiple stock cocks and micro air bubbles) and increase in biological signals (increase HR, BP, contractility).

HOWEVER, the damping coefficient is proportional to (viscosity X length X density)/(diameter X stiffness X density).
In other words, underdamping is caused by short, wide and stiff tubing.

The causes of ringing and damping seem to contradict each other. That is what is most confusing me, if in fact they are synonymous.

I guess I'm confused how ringing, damping and natural frequency the transducer system all relate to one another.

Help me.

None of this matters in real life or will alter your practice in any way.

Further, even if you learn all this theory, real systems are much more complex than such theoretical models.

Much the same as a lot of other anesthesia "knowledge". For instance, mapleson circuits, halothane questions, etc etc...

Would be better if they actually taught u guys some pain and icu stuff (both enormous and sophisticated fields), relevant recent and landmark articles, got u TEE certified by the end of residency etc, instead of asking about this Horsecrap. I was rolling my eyes throughout the written boards, which I passed the first time by plowing through this junk.

Another reason we are losing to the CRNAs...

Anyway, my advice is to create your own destiny by reading very regularly from relevant sources such as the above types of knowledge, to rise above the disasters of our field. Knowing more about the theory of Aline waves is not enough. You need to look beyond what is taught in residency, from the get go, while still learning the minimum needed of this kind of knowledge to pass your boards...this level of nitpicking from your question is way beyond the minimum.

I use almost nothing that I learned in residency in my everyday practice of pain, literally! And I love reading and learning these days, because it actually matters and changes my practice.

End rant...

 

[Noyac]

Thanks OP, now I'm as confused as you are. 🙁

 

[sigrhoillusion]

Thanks OP, now I'm as confused as you are. 🙁

It'll be OK.

Just guess "C".

 

[epidural man]

Hello, I'm doing a little reading and really confused about damping and ringing and wanted to see if anyone can clear up my confusion.

1. I originally thought ringing was synonymous with underdamping, is this true?
2. I understand that ringing is the overlapping of natural frequency signals and biological signals. Where you get a decrease in natural frequency (caused by long, narrow tubing, multiple stock cocks and micro air bubbles) and increase in biological signals (increase HR, BP, contractility).

HOWEVER, the damping coefficient is proportional to (viscosity X length X density)/(diameter X stiffness X density).
In other words, underdamping is caused by short, wide and stiff tubing.

The causes of ringing and damping seem to contradict each other. That is what is most confusing me, if in fact they are synonymous.

I guess I'm confused how ringing, damping and natural frequency the transducer system all relate to one another.

Help me.

I don't remember what ringing is. I know what hyper resonance is - which will over-estimate the BP (or as you say, underdamped system). An over damped system will underestimate the BP.

A highly damped system is caused by small diameter, complaint tubing, stop cocks, bubbles, etc - or a system with a natural resonance that can't respond to the frequencies required (but I think this is rare).

This is just restating what you stated - so I don't think you should be too confused. Do you remember that trick where you pull on the a-line thingy, and then measure the 2nd and third peak amplitudes (from the ringing) and that ratio helps you figure out your damping coefficient.

Although the math isn't all that useful, the concept certainly is - and I think it is useful to understand causes of over damped or underdamped systems.

I don't know that formula you mention. I just remember the damping coefficient being the square root of a bunch of numbers that included the amplitude ratio of the reverberations.

 

[Scotty_G]

Academic masturbation at its best :0

 

[fakin' the funk]

short, wide and stiff tubing.
...
Help me.

Heh