Hey guys this is Tammy Dunnett with NurseMinder and today we are talking about
oxygen saturatio,n in particular we're going to talk about how to take the
oxygen saturation reading. We're going to talk about what the waveforms actually give
us information about, and a little bit about prepping your patient and clinical
consideration, and of course we're gonna do all of that right after this. Welcome
back my name is Tammy and this is NurseMinder and on this channel we do
everything nursing so if you're new here consider subscribing below so that you
get the next video when it's released. So talking about oxygen saturation, what we
typically do is just kind of put this on a person's finger, take a reading write
some numbers, and I don't know if we really give too much thought about what
exactly we are measuring. So we're going to talk about that today.
So our oxygen saturation our SPO2 as we call it, is a measurement of
oxygenation, and oxygenation is a reflection of our perfusion and
ventilation. So our abilities to breathe in and get rid of oxygen and the
abilities for our lung cells to transfer oxygen and carbon dioxide from the blood
system into the lungs and from the lungs into the blood system. When using a pulse
oximetry to measure oxygen saturation we're really looking at the hemoglobin
that is in the red blood cells and how much of that is bound to oxygen. So each
red blood cell has a certain capability to carry a volume of oxygen and that's
what we're measuring, and it's measured in a percentage. So in a normal healthy
adult the normal values are greater than 92%. Now depending on if you have some
other pathologies such as COPD, we may actually want it to be lower
88% or higher because of what's happening within the lungs.
In terms of preparing your patient for an O2 sat reading, education around how
it is non-invasive - so there is no pain at simply a light pressure on your
finger is important - and then it will simply need to sit there for about 30
seconds while it adjusts and it reads and you get a baseline. Now in preparing
your patient and selecting the place that you will do your monitoring we
often will use the hand and the ring finger to complete that process. Now we
want to make sure that the digits are free from nail polish and that they are
warm and they are pinK. If they are cold and blue you're gonna get a really
low reading and you will want to see if there's a digit that actually is pink. So
either hand is fine in some cases you might also need to use the toes.
Other locations for doing O2 monitoring could be the ear if you've got the ear
ones and the feet in infants we tend to wrap the sensor around their foot pad.
Now when it comes to waveforms there is a characteristic pattern that we would
expect to see in a healthy individual and that's this first one here; the
normal waveform for a pulse oximeter, and you'll have seen it on my reading as
well that we have this sharp rise up and then kind of almost a hill on the way
down. This is called the dicrotic notch if you see that present, it is not always
there, but we have this rise and fall to baseline, rise and fall to baseline, and
this will be considered normal, and with this we consider a normal stroke volume
and peripheral vascular resistance as well. When we have a weak wave form you
may only see a slight rise and fall and a slight rise and a slight fall. This may
be due to hypovolemia that they have a decreased volume in the vasculature,
which is causing a decreased stroke volume and there may be increased
peripheral vascular resistance such as with heart failure. When we have a large
bounding waveform you'll see these really tall structures show up and
they're consistent across that's not a problem, but they're taller and a little
bit more pronounced than usual so somebody has a fever,
you know the vasculature has dilated and we're really pumping that fluid through
the heart because we're circulating oxygen, we may have an increased stroke
volume, and with that dilation we have a decrease in peripheral vascular
resistance. Other conditions that may be consistent with this pattern would be a
aortic regurgitation, anemia, and an increasing in intracerebral pressure
ICP.
There are some limitations to the use of a pulse oximetry and that would be
nail-polish on the fingers, dark nail-polish limits the ability for that
red light to shine through. The second would be if the patient is already cold
and clammy, there might be perfusion problems we're going to get an
inaccurate reading potentially, and then the third is when they're shivering or
there's artifact that can influence the reading.
Clinically there may be some limitations as well.
Patients who are anemic have fewer red blood cells. that doesn't mean that their
hemaglobin concentration won't actually be greater than 92 percent because the
hemoglobin that is bound to that red blood cell may in fact be saturated to
an efficient level but our patients may still be symptomatic because they have
fewer of them, which means there's less oxygen available to the cells when they
arrive. So if you do have a symptomatic patient who is anemic and they have a
normal SPO2 then you may still need to use some oxygen, trauma patients fall
into the same category in the sense that if they are bleeding, they are losing
blood, but they may have a normal SPO2 reading and still require oxygen if they
are in distress. Carbon dioxide is the third clinical consideration I want to
talk about at this point. So carbon dioxide has a greater affinity to bind
to hemoglobin than oxygen and in the presence of carbon dioxide it will still
appear as if our patients are sat'ing with oxygen greater than 92% which can
be misleading. If a patient is at all suspected to have carbon dioxide
poisoning you'll want to apply oxygen to improve their oxygenation and one of the
tests they may order in order to definitively identify their oxygen
status would be an arterial blood gas. One of the questions I get asked is how
long will it take before I notice a change in my patient status if I give
oxygen and I'm monitoring their SPO2. Well here's something I like to have my
students do is to put on a sat probe and hold their breath. In fact let me do that,
let me grab my sat probe. See that change. Currently my oxygen saturation is at 97%
I'm gonna hold my breath for as long as I can ....
Okay that's getting pretty long and you see my oxygen hasn't changed at all huh
so it can take a couple minutes before you see a change in your patient status
when you're increasing or decreasing oxygen saturations, so do be sure to
check back in on them. That's our less of an oxygen saturation
so be sure to comment below and let me know how this has helped you and if
you've got some more information of course share it because you know that we
are stronger together. And share this with your friends let them know that
you've watched a really cool video, like it, thumbs up, and until next time make it
a great day :)