00:01
Now let's discuss
the interpretation
of fetal heart rate tracings.
00:06
So let's go over some
terminology
and some nomenclature.
00:09
When we talk about the fetal
heart rate tracing,
we talk about the baseline,
the variability
and accelerations.
00:17
When we talk about contraction,
the bottom part of this example
we discuss if the contractions
are normal and what
tachysystole means.
00:26
Let's start with baseline.
00:28
So a normal baseline is between
110 beats to a 160 beats per minute.
00:33
And this is for the fetal
heart rate.
00:37
Tachycardia is considered to be
160 beats per minute sustained
for a 10 minute time frame.
00:43
And bradycardia is considered
to be less than
100 beats per minute when it's
sustained for a 10 minute time
frame.
00:52
So variability talks about
the ability of the fetal heart rate
to change above
or below baseline.
00:59
When the variability is absent
that means there's no change in
the baseline.
01:04
When it's minimal, it means it's
less than 5 beats per minute.
01:08
Moderate is 6 to 25
beats per minute.
01:11
And marked is greater
than 25 beats per minute.
01:14
In our example here, we would
call this moderate variability.
01:19
For accelerations,
we divide them into two categories.
01:23
After 32 weeks,
it is an increase in fetal heart rate
by 15 beats per minute for 15 seconds
before 32 weeks, and increase
in fetal heart rate by ten beats
per minute for 10 seconds
is considered an acceleration.
01:37
Now remember, if the increase in heart rate occurs
for over 2 minutes is called a change in baseline.
01:44
Now, contractions.
01:47
A normal amount of contractions
are 5 or less contractions in
a 10 minute time frame.
01:53
Uterine tachysystole means
greater than 5 contractions
in 10 minutes.
01:58
Now there's something
called Montevideo Units.
02:02
When normally a patient is
monotronant labor they have
an external fetal monotron.
02:07
Because it sits at top of
the abdomen, it only tells us
how often a patient is
contracting.
02:13
It doesn't tell us how strong
those contractions are.
02:17
Within intrauterine pressure
catheter we're able to determine
the strength of
the contractions.
02:22
Now how do we do this.
02:24
We take a 10 minute strip
or a 10 minute tracing.
02:28
We look at the contractions
during that time and we measure
the area under the curve.
02:33
Now a normal amount of
contraction or strength
of contraction would be between
180 to 220 Montevideo units.
02:43
That's considered to be adequate
contractions to allow labor
to progress.
02:49
Now that we've talked about
the fetal heart rate tracing
and some of the terminology,
let's talk about
the nomenclature.
02:56
So why do we even look
at fetal heart tracing.
02:59
Well, fetal heart rate tracing
provides an information to us
to tell us about the current
acid-base status of the fetus.
03:06
Now we have 3 categories.
03:08
Category 1 which is normal.
03:11
Category 2 which can
be indeterminate.
03:13
And Category 3 which
we consider abnormal.
03:16
Let's see what makes
each of those categories.
03:21
So a category 1 tracing.
03:23
In order for a tracing to be
considered Category 1,
such as this one,
the fetal heart rate has to be
between 110 to 160 beats
per minute.
03:33
There must be
moderate variability.
03:35
And there are no late
or variable decelerations.
03:41
Now, a Category 2 tracing.
03:44
Again this is indeterminate
to determine the acid-base
status of our fetus.
03:51
So the fetal heart rate can
be between 110 to 160 beats
per minute.
03:56
But it can also be 100 beats per
minute which remember that means
bradycardia.
04:01
But variability must be present.
04:04
It can be greater than 160 beats
per minute which again that
means tachycardia.
04:09
But again variability
must be present.
04:14
As far as the variability it
can be minimal or moderate.
04:18
Or if it is absent, such as in
this case, there can be no late
or variable deceleration
for it to be considered
a Category 2 tracing.
04:28
Acceleration should be present.
04:32
And if there are decelerations
which again those can be late
or variable, they can be present
if there is minimal or moderate
variability present.
04:44
Now, Category 3 tracing.
04:46
This is considered abnormal.
04:47
And this would mean that
the acid base fetal status
is abnormal.
04:55
So, Category 3.
04:56
What makes a Category 3 tracing.
04:58
As far is variability
it is absent with late
or variable decelerations.
05:03
Such as in this tracing.
05:07
There can be bradycardia which
again is less than a 100 beats
per minute.
05:11
Or something called as
Sinusoidal Pattern.
05:13
You also see this called
a see-saw pattern.
05:15
And that actually
shows fetal anemia.
05:19
Now let's talk about
the different types of decelerations
that we can see on
a fetal heart rate tracing.
05:24
We have early decelerations.
05:26
These decelerations particularly
mirror the contractions
and these are physiologic.
05:31
They are due to the head
compression and due to
stimulation of the vagus nerve.
05:35
Because they are physiologic,
there's nothing that we need to
do about them.
05:41
Variable decelerations, you can
see there's a sharp decline in
the fetal heart decline and
there's a sharp incline back to
the baseline.
05:50
Variable decelerations are
due to cord compression.
05:54
Now, they can be released by
doing amino infusion which is
placing fluid inside the uterus
through the intrauterine
pressure catheter.
06:02
That allows the fetus to get off
of the cord and to release these
variable decelerations.
06:08
Now late decelerations
are little bit more ominous.
06:11
These are due to
the utero-placental insufficiency.
06:15
These we do have to address
and we do want to correct.
06:18
So how do we address them.
06:20
1. We give oxygen to the moms
so there's more oxygen going
to the fetus.
06:24
2. If we are given pitocin
to make contractions happen,
we want to stop the pitocin.
06:30
3. We want to give IV fluids
because that will allow more
fluid to go to the placenta.
06:36
And then 4. We want to commonly
place the patient
in left lateral decubitus.
06:41
So that means we roll them
on to the left side.
06:44
That will rotate the uterus
off of the inferior vena cava.
06:48
So we have increased venous
return to the placenta.
06:53
Now let's take a case.
06:55
You are called to the bedside
of a 23 year old Gravida 1 Para 0
female who was admitted
in active labor.
07:04
On her most recent cervical
exam she was 5/90 and -1.
07:09
She received an epidural
approximately 10 minutes ago.
07:13
Her fetal heart rate tracing
which was Category 1, is now
shown to be this.
07:19
How would you
describe this tracing?
What nomenclature
would you use?
Now would you say that,
A. The patient is having early
decelerations, most likely from
rapid cervical change.
07:37
B. Patient is having late
decelerations most likely from
rapid cervical change.
07:43
C. Patient is having late
decelerations most likely
from hypotension related
to recent epidural placement.
07:50
or D. Patient demonstrates
at Category 1 fetal heart tracing.
07:57
The answer is C.
07:58
We would describe this fetal
heart rate tracing
as a Category 3.
08:02
We can see that the patient
is having a large late
deceleration.
08:06
Now it's important to remember
that when the epidural is
placed, a lot of times moms
will suffer from hypotension.
08:12
This causes utero-placental
insufficiency.
08:15
And the fetus will compensate
by having late decelerations.