Martel et al 5
When evaluating the agreement level between the methods for DBP
values in the three pressure ranges, the bias
was dependent on the pressure range with the smaller
bias observed at low DPB.
Running additional pulse wave analyses to identify
correlation of SBP and DBP, a high correlation was found
for SBP, whereas a similar poor correlation was observed
for DBP. However, these analyses suggested a good correlation
between DBP measured with telemetry and MBP measured with HDO. This observation was confirmed by correlation
analyses performed on these data
showing a CC of 0.90 ± 0.02. In addition, a good correspondence between DBP
by HDO and MBP by telemetry
was achieved when tested by means of the Bland-
Altman method (Table 3).
We assessed heart rate during the simultaneous BP
measurements with HDO measurement through the
experiment. On the first day of BP measurement with
HDO, the mean level of heart rate during the recording
was 197 ± 6 beats/min. On the following days, heart rate
during measurement decreased to achieve a level that
remained below 180 beats/min, suggesting that animals
were accustomed to the recording conditions and were
apparently undisturbed by the HDO measurement
(Figure 4).
Discussion
Hypertension in cats is mainly secondary to an underlying pathology,
particularly in cats with chronic kidney
disease. To predict outcomes in affected cats, proteinuria
is arguably a better clinical parameter than measurement
of BP.16 However, BP measurements in studies of spontaneous chronic
kidney disease in cats have relied upon
devices that meet neither the AAMI nor the ACVIM criteria for validation,6
which may have compromised the
reliability of BP measurements. Future studies will be
necessary to assess the reliability of BP measurements
obtained with a validated device.
It is now established that about 20% of hypertensive
cats have idiopathic hypertension.17 The diagnosis of idiopathic hypertension is based on elevated SBP
and DBP
above 150 mmHg and 95 mmHg, respectively, associated
with target organ damage (TOD) depending on its risk
category.3 Hypertensive cats frequently display TOD,
Table 1 Correlation between systolic blood pressure
(SBP) and diastolic blood pressure (DBP) values
measured with high-definition oscillometry and telemetry
Parameter Pressure
group
Correlation
coefficient
SBP Low 0.71 ± 0.26
n = 5-6
Normal 0.78 ± 0.09
n = 14-19
High 0.87 ± 0.07
n = 10-13
Overall 0.92 ± 0.02
n = 25
DBP Low 0.51 ± 0.21
n = 7-19
Normal 0.40 ± 0.34
n = 6-20
High 0.51 ± 0.29
n = 5-9
Overall 0.81 ± 0.02
n = 25
n = number of measurements used for individual correlation analysis
for each cat
Mean (± SD) data calculated from individual data obtained in six
animals
Figure 2 Bland-Altman plot of agreement between systolic blood pressure (SBP) and diastolic blood pressure (DBP)
measured with high-definition oscillometry and telemetry in cat number 2008018. Mean difference (bias): - -- - -- - -- -, low limit
of agreement (-2 SD) and high limit of agreement (+ 2SD): - - - - - - -. SBP: bias = -2.7 mmHg; limits of agreement = ± 20.7
mmHg; percentage of paired measurements lying within a difference between the two methods less than 10 mmHg = 84%;
less than 20 mmHg: 100%. DBP: bias = 19.5 mmHg; limits of agreement = ± 24.5 mmHg; percentage of paired measurements
lying within a difference between the two methods less than 10 mmHg = 25%; less than 20 mmHg = 47%