Now, we're going to put our stethoscopes away for a bit,
we'll come back to them in a minute to demonstrate percussion of the chest.
This is an extremely useful skill first described by Auenbrugger in the 1800s
where he found that he's father had shown him that tapping on a cask of wine
could give him a sense as to how much wine was left in the cask,
and he, as a physician, learned that you could do the same thing
with the chest wall to discern whether or not there is fluid in the chest.
So percussion is a very important skill that we'll use certainly in the abdomen
and particularly here in the chest.
A few important points about percussion,
when you are percussing any organ you're really looking for three specifics sounds,
resonance, tympany, and dullness.
Dullness is a very short, flat, low pitched sound that you would hear
simply if you percuss over some muscle, so we can do that now.
Barely hear anything at all.
It's a very short quick sound that doesn't -- doesn't last very long, since it's short.
The next sound we were listening for is resonance.
Resonance is the sound of a chorus of low pitch sounds throughout a tissue
that is relatively hollow.
It's not a hollow viscus, it's not a drum, but it is nonetheless airy and light,
and that perfectly describes the chest,
right, so let's take a listen to see what the sound of resonance sounds like.
You'll note that my finger is typically, for most physicians or clinicians,
you're hitting the distal segment of your middle digit.
I'm keeping my other hands off the chest to avoid dampening down the sound
and that's the sound that I'm reproducing which is a sound of resonance.
In contrast tympany is -- since that's also described a particular drum in somebody's drum set,
is a specific pitch and you're typically looking for tympany
when you percuss over a hollow viscus, the stomach would be the most obvious example.
When you percuss over the stomach, you'll actually hear one pitch,
it's a hollow sounding sound and it tends to have a longer duration
and it's lower in pitch depending upon the size of the viscus that you are percussing.
Maybe we should demonstrate that now as well.
So this is the sound of tympany -- you can tell it's a single pitch.
It's hallow sounding and it's relatively long as well.
Normally the chest should only have resonance sounds
and we'll talk about what the significance is of finding sounds other than resonance in a moment.
Alright, now we're back at the examining the chest again with percussion.
We're going to march down and compare one side to the other as we engage in percussion.
And you'll note that right around here is the transition point
where I go from resonance to dullness,
which in this case would be me moving from above the diaphragm
where I'm percussing the lungs, to below the diaphragm
where I'm presumably I'm percussing the spleen on the left side
and on the right side I'd be percussing the liver.
So just by doing that simple technique you can get a good sense
of where the bottom of your lungs is located.
You can imagine that if his lungs were full of fluid or if one side is full of fluid,
we'd have asymmetry where that dullness would occur much earlier on one side
than on the other side.
Incidentally, for some folks who may have very small hands
or have trouble making a significant sound with their,
this is called the plexor, this is the pleximeter,
you can actually cheat by using a reflex hammer like so.
Makes a bit more noise if you need to, to create a louder sound.