Accuracy of indirect oscillometric blood pressure measurement
in anesthetized neonatal foals
A diagnostic study
And
Course of blood pressure in neonatal foals
A short literature study
D.J.J. van den Broek
Research Internship article
Supervisor: Dr. I.D. Wijnberg
August 2013
Table of contents
Table of contents……………………………………………………………………………………………………………………1
Accuracy of indirect oscillometric blood pressure measurement in anesthetized foals
……….………2-14
Abstract………………………………………………………………………………………………………………………………….2
Introduction……………………………………………………………………………………………………………………….2-3
Material and Method………………………………………………………………………………………………………….4-5
Results………………………………………………………………………………………………………………………………5-11
Discussion………………………………………………………………………………………………………………………12-13
Literature……………………………………………………………………………………………………………………….13-14
Course of blood pressure in neonatal foals………………………………………………………………….15-16
1
Accuracy of indirect oscillometric blood pressure measurement
in anesthetized neonatal foals
D.J.J. van den Broek, Faculty of Veterinary Medicine, Utrecht University
Abstract
To obtain the arterial blood pressure in horses several techniques and devices can be used. Every
technique and device having its own advantages and disadvantages. In this study the Microlife BP
A100 Plus with Philips cuff M1872B size 4 is being analyzed. As participants on this study we used
foals which were undergoing surgery or were staying in the intensive care unit. The foals
undergoing surgery participated in the part of the study that analyses the accuracy of the blood
pressure device. The foals staying in the intensive care unit participated in the part of the study
that intended to investigate the blood pressure varieties in critical care foals during the day.
Statistical analysis revealed the device to be inaccurate for blood pressure measurements. There
seems to be an overestimation of the systolic and diastolic pressure with a low accuracy and a low
repeatability. However, for measuring the heart frequency (pulse rate) the device seems to be both
accurate and a precise in anesthetized foals. The data collected from the foals in the intensive care
unit was not further analyzed due to the performance of the device. The advice of the authors is
not to use the Microlife BPA 100 plus oscillometric blood pressure device in combination with the
Philips M1872B #4 cuff to obtain blood pressure values in foals.
Introduction
The peripheral arterial blood pressure can be
measurement of pneumatic cuff pressure
measured
gives an estimation of the peripheral blood
directly
by
intra-arterial
catheterization or indirectly by placement of
pressure.
an inflatable cuff. The advantage of direct
measurement
blood pressure measurement are the close
applicable, although careful positioning of the
relationship to the actual central arterial
cuff is necessary and continuous monitoring
pressure and the possibility of continuous
is not an option (Geddes, 1977).
monitoring. However a risk is involved during
repositioning or restraint of foals since
Several
it
pressure
Indirect
is
blood
non-invasive
techniques
of
measurement
and
indirect
in the
blood
horse
cause of thrombus formation (Corley, 2002;
techniques differ in their method to record
Franco et al., 1986; Taylor, 1981).
the return of pulsatile flow. Methods depend
auscultation,
mostly
are
described
on
literature;
easy
might be a port d’entrée for infection or a
Indirect blood pressure is measured in a
in
pressure
palpation
or
these
Doppler
non-invasive manner using an inflatable cuff
technique (Brown & Holmes, 1981; Taylor,
and
1981).
a
device
for
the
detection
of
the
peripheral pulse. The cuff is inflated up to a
The
middle
coccygeal
artery
is
most
pressure greater than the systolic pressure
commonly used to measure indirect blood
and then gradually deflated. Detection of the
pressure measurement and seems to have
peripheral
the
pulse
waves
together
with
2
most
accurate
agreement
with
the
arterial pressure, but the dorsal metatarsal
1975;
Glen,
1972)
although
some
artery can also be used (Giguère et al., 2005;
investigators claim the indirect method to
Parry et al., 1982; Covington & McNutt,
overestimate systolic pressure (Riebold &
1931).
Evans, 1985).
The auscultatory techniques are suitable for
As mentioned above, the middle coccygeal
the measurement of changes in systolic
artery is generally used for indirect blood
pressure
changes
pressure measurement. The cuff should be
accurately. But the method is subjective,
carefully placed tight at the base of the tail.
sensitive to external motion and sometimes
Clipping the hair of the tail is not necessary
fails to detect Korotkoff sounds (thumping
(Corley, 2002; Parry et al., 1982).
and
reflect
these
sounds being heard when the pressure in the
The
accuracy
of
the
measurement
is
cuff is between the systolic and diastolic
influenced by the bladder width. A width of
pressure)
about one-fifth to one-quarter of the member
(Riebold & Evans, 1985; Muir et
al., 1983; Ellis, 1975).
Oscillometric
circumference seems optimal (Latshaw et al.,
techniques
on
1979;) . Blood pressure is underestimated by
palpation of pulse waves and are not affected
5% using a bladder width of 30% of member
by motion, bumping or extraneous noise.
circumference (circumference of the limb or
Changes
diastolic
tail) and a 5% overestimation occurs using a
pressures are reflected accurately, but the
bladder with a width of 20% of the member
blood pressure values are lower than directly
circumference (Latshaw et al., 1979; Geddes
obtained pressure values. ( Nout et al., 2002)
et al., 1977). A bladder width/tail girth ratio
Nevertheless, the measurements of mean
of 0.482 underestimates the systolic pressure
and diastolic pressure are useful due to a
and overestimates the diastolic pressure both
good
by 8.8% (Parry et al., 1982).
in
mean,
correlation
are
systolic
between
based
and
directly
and
indirectly obtained blood pressure values. In
In foals the oscillometric technique with a
foals the level of agreement of the systolic
cuff around the middle coccygeal artery is
pressure was insufficient (Nout et al., 2002;
most frequently described. There seems to be
Holdstock
1997;
a good correlation between indirectly and
Franco et al., 1986; Riebold & Evans, 1985;
directly measured values, but the indirectly
Muir et al., 1983).
obtained
Methods using the Doppler technique for
Indirect
detection
close
placing an inflatable cuff seems to be an
relationship to true values obtained by direct
acceptable method for measuring at least the
measurement. One study reports that this
mean arterial pressure in foals (Giguère et
method
al., 2005; Nout et al., 2002; Franco et al.,
et
al.,
of
is
the
not
anesthetized
1998;
pulse
Branson,
disclose
acceptable
dorsally
for
recumbent
a
use
in
horses,
values
blood
are
pressure
constantly
lower.
measurement
by
1986).
because 5% of measurements obtained by
In this research we will study the accuracy of
Doppler have an error rate greater than 20.2
the Microlife BP A100 Plus with Philips cuff
mmHg (Bailey et al., 1994; Latshaw et al.,
M1872B
1979; Gay et al., 1977).
measurement device.
In general, the indirect methods tend to
underestimate
intra-arterial
pressure
(Branson, 1997; Franco et al., 1986; Ellis,
3
size
4,
an
indirect
blood
Material and Method
Intensive care indirect measurements.
Direct vs indirect measurements.
Design: Diagnostic study
Design: Diagnostic study
Participants: Neonatal foals up to 3 months of
Participants: Neonatal foals till 3 months of
age brought to the Intensive care unit of the
age brought to the Equine University Clinic of
Equine University Clinic of the faculty of
the faculty of Veterinary Medicine, Utrecht,
Veterinary Medicine, Utrecht, NL during
the
NL and undergoing intestinal surgery during
period of 01-03-11 t/m 31-05-11. Eight foals,
the period of 01-03-11 t/m 31-05-11. Five
male and female, participated in this study.
foals participated in this study
Equipment:
Equipment:
Blood pressure monitoring device (Microlife
A Blood pressure monitoring device; Microlife
BP A100 Plus with Philips cuff
BP A100 Plus with Philips cuff M1872B size 4
M1872B size
4)
was used to measure the blood pressure
Data collection:
indirectly.
For faculty staff and students an instruction
A 20G catheter was placed intravenously
form
directly
was
made
in
order
to
keep
the
after the foals were anesthetized,
measuring method constant.
and a BD DTX plus pressure transducer in
Foals staying in the intensive care unit were
combination with a datex-ohmeda S5 monitor
measured every two hours during 24 hours.
was used to record the intra arterial blood
The blood pressure was measured with the
pressure.
indirect method using the Microlife device.
Data collection:
The cuff was placed around the base of the
The blood pressure of foals that were under
tail in order to measure the pressure of the
anesthesia was measured every five minutes
middle
during the entire duration of the surgery. The
coccygeal
artery.
(Corley,
2002;
Giguere, 2005)
cuff around the base of the tail was placed at
To reduce the influences of the position of the
the moment the foal was under anesthesia
foal on the pressure, all the foals were
and lying on its back on the operating table.
measured
Methods
lying
down
while
taking
into
employed
were
the
indirect
account the vertical relation to the heart.
measurement with the Microlife device and
(Corley,2002)
Philips cuff around the base of the tail and
Every measuring point consisted of three
direct
measurements within three minutes. Time,
catherization of the a. facialis with a 20G
systolic pressure, diastolic pressure and pulse
catheter. The catheter was attached to an
frequency were recorded. (Corley, 2002)
electronic pressure transducer (BD DTX plus
During the measurements with the Microlife
pressure transducer) which was zeroed and
device the heart frequency was measured by
placed at the level of the sternal manubrium.
auscultation of the heart or palpation of the
The electronic pressure device was joined to
ictus cordis. Pulse frequency (heart rate),
a monitor (datex-ohmeda S5 monitor) which
body temperature and breathing rate were
displayed
documented . (Corley, 2002)
pressure and the pulse rate. (Nout, 2002;
measurement
the
systolic
with
intra
pressure,
arterial
diastolic
Corley, 2002; Giguere, 2005)
Measuring points were every five minutes.
During these measuring points the blood
4
pressure values were noted for the indirect
if there is any systematic difference between
device and at the same time the direct values
the obtained measurements. Bland-Altman
were obtained from the monitor. Systolic
plots are used to assess the agreement
pressure, diastolic pressure and pulse rate
among two different methods that measure
were documented in a time table. All data
the same parameter. In these plots the x-axis
collected was pooled in one group. (Nout,
is
2002; Giguere, 2005)
measurement (direct – indirect)/2 and the y-
Statistical analysis:
axis is assigned to the difference between
To investigate the accuracy and precision of
every measurement (direct – indirect). If
our
the
there is a systematic difference between the
Microlife BP A100 Plus with Philips cuff
direct and indirect method, for example one
M1872B size 4, in comparison to the direct
of
method, the following statistical analyses
considered to be too high, all of the dots in
were
difference
the plot will be located above or below the
obtained
zero line. If the dots are scattered in the plot
measurements) was calculated to investigate
it means that there is no consistent bias. The
the accuracy of the device. A paired sample t
lines in the plot indicate the mean difference
test was used to reveal if the difference
(solid line), or mean bias, and the limits of
between the values obtained by the direct
agreement (dashed lines). The
and
limits of agreement lines get, the closer the
indirect
blood
made.
between
The
directly
indirect
significant,
pressure
bias
and
(mean
indirectly
method
meaning
device,
the
was
statistically
device
to
be
assigned
the
to
methods
correlation
the
mean
gives
between
the
results
two
of
every
that
are
closer the
types
of
inaccurate. The confidence interval was set at
measurement. The closer the line of the
95%. The limits of agreement (d-2SD and
mean difference is to zero, the more similar
d+2SD) were calculated to investigate if the
the measurements are. (Vocht de, 2012)
device, obtains precise blood pressure values.
Bland Altman plots were made to investigate
Table 1. Mean and standard deviation of the direct and indirect measurements of blood
pressure.
Systolic
Diastolic
Mean pressure
Pulse rate
Measurement
N
Mean
SD
direct
indirect
direct
indirect
direct
indirect
56
56
56
56
56
56
66,54
89,91
40,13
51,75
39,670
70,830
13,280
15,965
6,742
13,275
24,8269
13,6486
direct
indirect
56
56
103,38
102,73
14,398
14,643
Table 1 shows the mean values of the systolic, diastolic, mean pressure and pulse rate for both the
direct and indirect measurements. Also the standard deviation (SD) is given which shows how
much variation exists from the average. N shows the number of valid observations.
5
Results
The data collected from the foals undergoing
In figure 1 the indirect and direct obtained
surgery were pooled in one group since they
blood pressure values are plotted for the
were similarly attached to both the direct
systolic, diastolic, mean pressure and pulse
blood pressure device as well as the indirect
rate values with the line of equality for
blood pressure device. This meaning; if the
reference. The line of equality is where X and
two devices both work properly they would
Y are exactly the same. Figure 1 a shows the
measure the same blood pressure. The group
scatterplot for the systolic pressure. The dots
consisted
indirect
are above the line of equality meaning the
method failed in one of these foals. The direct
indirect device to overestimate the systolic
method failed in two foals. Leaving two foals
pressure. Figure 1 b shows the scatterplot for
to participate this research. The indirect and
the diastolic pressure. Most of the dots are
direct method failed in three foals due to
above
incapability to place the cuff or intra-arterial
overestimation of the indirect device. The
catheter. The duration of the surgeries were
same goes for the mean pressure in figure 1
about 155 and 215 minutes. Fifty-six blood
c. Figure 1d shows the plot for the pulse rate.
pressure measurements were recorded from
The dots are centered around the line of
two foals which were undergoing surgery. The
equality, meaning a good correlation between
indirectly obtained
the indirect and the direct device.
were
5
foals.
However,
blood
compared
measured
blood
pressure
values
simultaneously
pressure
From
the
line
these
56
of
equality, meaning
values
the
bias
an
(mean
values,
difference between directly and indirectly
facial
obtained blood pressure values) and limits of
artery. The blood pressure was obtained by
agreement (2x the standard deviation of the
measuring
mean
difference) for systolic, diastolic, mean blood
pressure and pulse rate. In table 1 the mean
pressure and pulse rate were calculated and
and standard deviations of both the direct
are shown in table 2.
obtained
direct
with
the
by catheterization of the
the
systolic,
diastolic,
and indirect measurements for each are
given.
Table 2. Bias and limits of agreement for the blood pressure.
Descriptive Statistics
N
Mean
SD
Limits of agreement
Systolic
56
-23,37
12,585
-48,54; 1,8
Diastolic
56
-11,63
9,631
-30,892; 7,632
Mean pressure
56
-31,161
17,5326
-66,2262; 3,9042
Pulse rate
56
,64
5,154
-9,668; 10,948
In table 2 the mean difference for the systolic, diastolic, mean pressure and pulse rate is given.
Also the standard deviation (SD) is given, which shows how much variation exists from the
average. The limits of agreement show how much random variation may be influencing the ratings.
N shows the number of valid observation.
6
For the systolic pressure the mean bias is -
.64
23.37
of
agreement between -9.668 beats/min and
agreements of -48.54 mmHg and 1.8 mmHg.
10.948 beats/min. Figure 2 shows Bland
The diastolic and mean pressures have a bias
Altman plots, as described in methods, for
of
the blood pressure values.
±
12.585
-11.63
±
31.161±17.533
mmHg,
9.631
mmHg
limit
and
respectively,
-
5.154
beats/min,
with
limits
of
with
A paired sample t-test was used to determine
limits of agreement between -30.89 and 7.63
if a significant difference existed between the
mmHg
bias of the systolic, diastolic, mean pressure
and
mmHg
with
±
-66.23
and
3.90
mmHg,
respectively. The pulse rate has a low bias of
and pulse rate and is shown in table 3.
Table 3. Paired sample t-test showing the significant difference between the bias.
Mean
Std. Deviation
95%
Confidence
Interval
of
t
df
Sig. (2-
the
tailed)
Difference
Lower
Upper
Pair 1
Bias systolic
-23,375
12,585
-26,745
-20,005
-13,899
55
,000
Pair 2
Bias diastolic
-11,625
9,631
-14,204
-9,046
-9,033
55
,000
Pair 3
Bias mean pressure
-31,1607
17,5326
-35,8560
-26,4655
-13,300
55
,000
Pair 4
Bias pulse rate
,643
5,154
-,737
2,023
,933
55
,355
Table 3 shows the results of the paired sample t-test for the bias of the systolic, diastolic, mean
pressure and pulse rate. The significant difference, mean values and standard deviation are given
as well as the 95% confidence interval. To see if the means of the direct en indirect measurements
are different the t-value is shown. Degrees of freedom (n-1) are shown in the df queue.
Table 3 shows the results of the paired sample
89.91±15.965
t-test for the bias of the systolic, diastolic,
13.899. Meaning the values for indirect and
mean pressure and pulse rate. The bias is
direct measurements do not coincide. It also
measured by subtracting the obtained indirect
shows
values from the obtained direct values. The
between the bias of the diastolic blood pressure
mean and standard deviation (SD) are given as
and the mean pressure obtained by the direct
well as the lower and upper boundaries of the
method (Table 1: respectively 40.13±6.742 ;
95%
39.670±24.827)
confidence
interval.
The
significant
a
1:
mmHg),
statistically
Table
3:
significant
and
the
respectively
t(55)=-
difference
indirect
method
difference is shown for the bias in the most
(Table
51.75±13.275
right queue. To see if the means of the direct
70.830±13.649) with respectively
en indirect measurements are different the t-
t(55)=-9.046 and t(55)=-13.300. Meaning the
value is shown. The closer the t value is to
values for indirect and direct measurements do
zero, the more the values for direct and indirect
not coincide. The difference between the mean
coincide.
pulse rate obtained by the direct method (Table
Table
;
3:
1: 103.38±14.398) and indirect method (Table
The paired samples t test reveals a statistically
2:
significant
significant
significantly different (Table 3: t(55)=0.933).
difference = 0,000) between the mean systolic
Meaning the values for indirect and direct
blood pressure measurements obtained by the
measurements coincide.
difference
(Table
3;
direct method (Table 1: 66.54±13.280 mmHg)
and
the
indirect
method
(Table
1:
7
102.73±14.643)
is
not
found
to
be
Figure 1: a, b, c, d The mean values of the systolic (a), diastolic(b), mean pressure (c) and pulse
rate (d) determined by the indirect device (Y-axis) plotted against the mean values measured by
the direct device (X-axis). The line of equality is drawn in for reference.
a) Systolic: direct vs indirect systolic pressure (mmHg)
b) Diastolic: direct vs indirect diastolic pressure (mmHg)
8
c) Mean pressure: direct vs indirect mean pressure (mmHg)
d) Pulse rate: direct vs indirect pulse rate (beats/min)
9
Figure 2: a, b, c, d Bland Altman plots of the mean systolic diastolic, mean pressure and pulse
rate values. The bias is calculated by extracting the obtained indirect values from the obtained
direct values (Y-axis). The mean values are calculated by adding up the direct and indirect values
and dividing them by 2 (X-axis). Solid line: mean difference (mean bias). Dashed lines = limits of
agreement; upper: mean difference (mean bias) + 2x SD, lower: mean difference (mean bias) - 2x
SD.
a) Bland Altman systolic pressure (mmHG)
b) Bland Altman diastolic pressure (mmHG)
10
c) Bland Altman mean pressure (mmHG)
d) Bland Altman pulse rate (beats/min)
The results from the foals staying in the intensive care unit are not analysed due to poor
performance of the device as will be described in the discussion. Therefore it was redundant to put
the results together in graphs and figures in this article.
11
Discussion
In this study we investigated the accuracy
oscillometric technique as is used in our
and precision of the Microlife BPA 100 plus
device (Riebold & Evans, 1985).
oscillometric blood pressure device and the
The wide range between the limits of
Philips M1872B #4 cuff used for indirect
agreement (dashed lines in fig. 2a: bland
blood pressure measurement in foals.
altman systolic pressure) suggest that this
The
indirectly
obtained
blood
pressure
device
is
not
a
precise
method
for
values were compared with simultaneously
measurement of the systolic pressure. The
measured
values,
conclusion must be that the Microlife BPA 100
obtained by catheterization of the facial
plus oscillometric blood pressure device and
artery. In total we obtained 56 values from
the Philips M1872B #4 cuff is not a valid
two foals.
measurement system for systolic pressure in
From these 56 values we calculated the bias
the foal, with both low accuracy and low
(mean
repeatability. Nout et al. (2002) also found
direct
blood
difference
pressure
between
directly
and
indirectly obtained blood pressure values)
the
and limits of agreement (d-2SD and d+2SD)
pressure to be insufficient when obtained by
for systolic, diastolic, mean blood pressure
an indirect oscillometric method in foals.
and pulse rate (table 2 in results).
level
of
agreement
of
the
systolic
The device also has a low accuracy for the
The independent samples t test reveals a
measurement of diastolic pressure. Although
statistically significant difference between the
the bias for diastolic pressure is half as high
mean systolic blood pressure measurements
as the bias for systolic pressure, these values
obtained by the direct method and the
still
indirect method. In this study we agree that
significantly
the direct method is the gold standard,
between the limits of agreement (dashed
meaning the indirect device to be inaccurate.
lines
Fig 1a shows the scatterplot for the systolic
pressure) suggest that this device is not a
pressure. The dots are above the line of
precise method for measurement of the
equality meaning an overestimation of the
diastolic pressure.
blood pressure using the indirect device.
The device also has a low accuracy for mean
The conclusion is that the device used in this
blood pressure and tends to overestimate
study
and
this value (fig 1 c and fig 2c). The wide range
In
between the limits of agreement (dashed
contrast to this finding, other authors state
lines in fig. 2c: bland altman mean pressure)
that the indirectly obtained values tend to
suggest that this device is not a precise
underestimate systolic pressure (Branson,
method
1997; Franco et al., 1986; Ellis, 1975; Glen,
pressure. The mean bias line (solid line in
1972) and only one other study states that
figure 2 a,b,c) is nowhere near zero and
the systolic pressure is overestimated when
therefore the indirect measurements differ
using the indirect method (Riebold & Evans,
too much from the direct measurements.
1985). However, their device was based on
As far as the author is aware of, no other
auscultatory
authors reports about overestimation of the
tends
overestimating
to
be
the
systolic
technique
inaccurate
pressure.
and
not
on
overestimate
in
fig.
for
(fig
2b:
diastolic
1b).
The
bland
measurement
pressure
wide
altman
of
range
diastolic
the
mean
diastolic blood pressure using an indirect
12
method of blood pressure measurement.
obtained from the eight foals in the intensive
Again, the limits of agreement for both
care unit. Our aim was to investigate the
diastolic and mean pressures suggest this
trends in blood pressure during the day.
device
significant
These foals were measured using the indirect
difference between obtained values. Earlier
device and did not have an intra-arterial
reports about the use of an oscillometric
catheter and therefore the results cannot be
technique
analyzed.
to
be
for
imprecise
diastolic
with
and
mean
blood
pressure measurement in the horse show
In conclusion, the Microlife BPA 100 plus
good correlation and precision, when applied
oscillometric blood pressure device together
on foals (Giguère et al., 2005; Nout et al.,
with the Philips M1872B #4 cuff seems not to
2002; Holdstock et al., 1998; Branson, 1997;
be
Franco et al., 1986; Riebold & Evans, 1985;
measurement in anesthetized foals. However,
Muir et al., 1983).
it seems to be both an accurate and a precise
The bladder width/tail girth ratio is of
a
valid
device
for
blood
pressure
device for heart frequency measurement in
importance for the accuracy of indirect blood
anesthetized
foals.
In
the
future,
more
pressure measurement (Parry et al., 1982;
measurements should be obtained taking the
Latshaw et al., 1979; Geddes et al., 1977).
bladder width/tail girth ratio into account.
In our study, this ratio was not calculated. All
foals were measured with the same size of
There
cuff. The unusual findings of overestimation
between directly and indirectly measured
of blood pressure by the indirect method in
values
our study could possibly be explained by
devices (Giguère et al., 2005; Nout et al.,
using a cuff with an unfitting bladder width
2002; Franco et al., 1986). Hence, the advice
(Geddes et al., 1977).
of the authors is not to use the Microlife BPA
Although the described device does not
seems
to
obtained
be
a
by
good
other
correlation
oscillometric
100 plus oscillometric blood pressure device
seem to be a valid system for blood pressure
in combination with the
measurement in foals, it seems to be both an
cuff to obtain blood pressure values in foals.
accurate
and
measurement
a
of
precise
the
method
pulse
for
rate
in
anesthetized foals. There is no statistically
significant
difference
between
the
Literature
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mean
Young
measurements of the directly and indirectly
between
the
limits
Accuracy
of
of
pressure
blood
indirect
in
neonatal foals. J Vet Intern Med 2005;
the device to be accurate for pulse rate. The
range
L.
measurement
obtained pulse rate measurements meaning
narrow
Philips M1872B #4
19:571-576.
of
2. Nout YS, Corley KTT, Donaldson LL, Furr
agreement (dashed lines in fig. 2d: bland
MO. Indirect oscillometric and direct blood
altman pulse rate) and the close position to
pressure measurements in anesthetized
zero of the mean bias (solid line in fig 2d)
and
suggest that this device is a precise method
Emergency and Critical care 2002; 12:75-
for measuring the pulse rate.
80.
3. Corley
The poor performance of the device as
described
above
makes
it
abundant
conscious
KTT.
neonatal
Monitoring
foals.
and
J
Vet
treating
haemodynamic disturbances in critically ill
to
neonatal foals. Part 1; haemodynamic
perform statistical analysis on the results
13
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12. Ellis P.M. The indirect measurement of
2002; 5:270-279.
arterial
blood
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in
the
horse.
4. Covington N.G. & McNutt G.W. Studies of
Equine Veterinary Journal 7: 22-26, 1975.
normal blood pressure in animals I: Blood
13. Gay C.C., McCarthy M., Reynolds W.T.,
pressure in the horse with brief note on
Carter
the ox. Journal of the American Veterinary
measurement of arterial blood pressure in
Medical Association 7: 22-26, 1931.
the horse. Australian Veterinary Journal
5. Franco R.M., Ousey J.C., Cash R.S.G.,
in
electronic
newborn
foals
using
sphygmomanometer.
J.B.
Indirect
blood
method
for
indirect
14. Geddes L.A., Chaffee V., Whistler S.J.,
an
Bourland J.D., Tacker W.A. Indirect mean
Equine
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Veterinary Journal 18: 475-478, 1986.
6. Glen
A
53: 163-166, 1977.
Rossdale P.D. Study of arterial blood
pressure
J.
American Journal of Veterinary Research
pressure
38: 2055-2057, 1977.
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15. Latshaw H., Fessler J.F., Whistler S.J.,
Veterinary Journal 4: 204-208, 1972.
Geddes
L.A. Indirect measurement of
7. Holdstock N.B., Ousey J.C., Rossdale P.D.
mean blood pressure in the normotensive
Glomerular filtration rate, effective renal
and hypotensive horse. Equine Veterinary
plasma flow, blood pressure and pulse
Journal 11: 191-194, 1979.
rate in the equine neonate during the first
16. Muir
W.W.,
Wade
A.,
Grospitch
B.
10 days postpartum. Equine Veterinary
Automatic
Journal 30: 335-343, 1998.
sphygmomanometry in horses. Journal of
8. Journal
of
Reproduction
and
Fertility,
the
Supplement 35: 623-628, 1987.
noninvasive
American
Veterinary
Medical
Association 182: 1230-1233, 1983.
9. Bailey J.E., Dunlop C.I., Chapman P.L.,
17. Parry B.W., McCarthy M.A., Anderson G.A.,
Demme W.C., Allen S.L., Heath R.B.,
Gay. C.C. Correct occlusive bladder width
Crump K.T., Golden C.S., Wagner A.E.
for indirect blood pressure measurement
Indirect Doppler ultrasonic measurement
in horses. American Journal of Veterinary
of arterial blood pressure results in a large
Research 43: 50-54, 1982.
measurement error in dorsally recumbent
18. Riebold T.W. & Evans A.T. Blood pressure
anaesthetized horses. Equine Veterinary
measurements in the anesthetized horse:
Journal 26: 70-73, 1994.
comparison of four methods. Veterinary
10. Branson K.R. A clinical evaluation of an
Surgery 14: 332-337, 1985.
oscillometric blood pressure monitor on
19. Taylor
P.M.
Techniques
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application
Veterinary Science 17: 537-540, 1997.
measurements
11. Brown C.M. & Holmes J.R. A review of
indirectly
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arterial
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in
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clinical
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Equine
Veterinary Journal 13: 271-275, 1981.
some factors which may influence values
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20. Vocht de, A. SPSS20 IBM SPSS statistics,
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2012
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14
Course of blood pressure in neonatal foals
D.J.J. van den Broek, Faculty of Veterinary Medicine, Utrecht University
In equine pregnancy the fetal arterial blood
al., 2008). Cardiac output increases as foals
pressure increases towards term. Increasing
gain weight, as does the stroke volume with
vasopressinergic
increasing age.
influences,
and
and
noradrenergic
changes
in
oxygen
During the first 6 days of life the ductus
metabolism contribute to the rise of the fetal
arterial
blood
pressure
(Giussani
et
arteriosus can be patent in normal foals. The
al.,
systemic
2005). Within the first 24 hours of life rapid
vascular
resistance
declines
gradually in the first 14 days of life. The
changes occur in the circulation of the normal
mean pulmonary arterial pressure is about 40
foal. A few hours after birth the mean
mmHg
systemic arterial pressure of the neonate is
and
within
24
hours
this
value
decreases to about 30 mmHg. The pulmonary
>80 mmHg and in the next two weeks this
vascular resistance also decreases rapidly
value increases to 100 mmHg (Thomas et al.,
during this first 24 hours leading to a
1987). Franco et al. (1986) report blood
decrease in blood pressure.(Thomas et al.,
pressure values in the first 3 days of life that
1987). There is a decrease of the resting
are substantially higher;144 and 74 mmHg
heart
on day 1 to 154.5 and 80 mmHg on day 3
rate
during
the
second
and
third
months of life (Lombard et al., 1984). Franco
postpartum for the systolic and diastolic
et al. (1986) found a significantly higher
pressures respectively. Others report about
blood pressure in thoroughbred foals than in
an increase in blood pressure during the first
pony foals, but Holdstock et al. (1998) could
3 days of age and unchanged values in the
not reproduce this difference. However they
following 7 days (Holdstock et al., 1998). In
found a marked individual variation in blood
pony foals, a rapid increase in blood pressure
pressure within breeds.
is seen in the first month. The systolic and
diastolic pressure increase respectively, from
In 1931, a weak relationship was noticed
81 and 35 mmHg on day one, to 100 and 41
between the age of the horse and its blood
mmHg on 7 days of age to 111 and 57 mmHg
pressure values (Covington & McNutt, 1931).
on 3 months of age. On 3 months of age the
Later studies report about a strong positive
blood pressure values are still below those in
correlation between age and blood pressure
adult
in the horse (Östlund et al., 1983). Studies
horses
(Lombard
et
al.,
1984).
Interestingly, Piccione et al. (2008) report
report
about a decrease in mean blood pressure
conscious adult horses to be between 90 to
during the first 40 days of life, with a mean
112 mmHg for the systolic pressure, 40 to
blood pressure of 105 mmHg on the first day
77.3 mmHg for diastolic pressure (Parry et
of life to 96.7 mmHg on the 40th day of life.
al.,
Rhythmicity is lacking in blood pressure of
Schilling, 1919) and a mean arterial pressure
neonatal
of 140 mmHg (Glen, 1972).
foals
and
this
leads
to
the
conclusion that blood pressure maturation is
absent in foals up to 40 days old (Piccione et
15
normal
1984;
blood
Covington
pressure
&
values
McNutt,
of
1931;
Literature
1. Covington N.G. & McNutt G.W. Studies of
normal blood pressure in animals I: Blood
pressure in the horse with brief note on
the ox. Journal of the American Veterinary
Medical Association 7: 22-26, 1931.
2. Franco R.M., Ousey J.C., Cash R.S.G.,
Rossdale
P.D.
pressure
in
electronic
Study
of
newborn
arterial
foals
blood
using
sphygmomanometer.
an
Equine
Veterinary Journal 18: 475-478, 1986.
3. Giussani D.A., Forhead A.J., Fowden A.L.
Development of cardiovascular function in
the horse fetus. Journal of Physiology
565: 1019-1030, 2005.
4. Glen
J.B.
Indirect
blood
pressure
measurement in conscious horses. Equine
Veterinary Journal 4: 204-208, 1972.
5. Holdstock N.B., Ousey J.C., Rossdale P.D.
Glomerular filtration rate, effective renal
plasma flow, blood pressure and pulse
rate in the equine neonate during the first
10 days postpartum. Equine Veterinary
Journal 30: 335-343, 1998.
6. Lombard C.W., Evans M., Martin L., Tehrani
J. Blood pressure, electrocardiogram and
echocardiogram
growing
pony
measurements
foal.
Equine
in
the
Veterinary
Journal 16: 342-347, 1984.
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C.,
Pero
R.W.,
Olsson
B.
Reproducibility and the influence of age on
interspecimen
pressure
in
determinations
the
horse.
of
blood
Comparative
Biochemistry and Physiology 74A: 11-20,
1983.
8. Parry B.W., McCarthy M.A., Anderson G.A.
Survey of resting blood pressure values in
clinically normal horses. Equine Veterinary
Journal 16: 53-58, 1984.
9. Piccione G., Assenza A., Fazio F., Giannetto
C., Caola G. Chronobiologic blood pressure
assessment:
rhythm
in
maturation
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the
daily
Biological
Research 41: 51-57, 2008.
10. Schilling S. The blood pressure of the
horse. Journal of the American Veterinary
Medical Association 55: 401-416, 1919.
11. Thomas W.P., Madigan J.E., Backus K.Q.,
Powell W.E. Systemic and pulmonary
haemodynamics in normal neonatal foals.
Journal of Reproduction and Fertility,
Supplement 35: 623-628, 1987.
16