Page 44 - Basic Monitoring in Canine and Feline Emergency Patients

inaccurate since large differences in the systolic and develop high sympathetic tone simply from trave-
diastolic pressures should yield an easy-to-detect ling to or entering the hospital, and therefore will
VetBooks.ir femoral pulse. tend to have a higher blood pressure reading in the
As mentioned above, the oscillometric unit should
hospital environment than in their home environ-
always report the heart rate at the time the pressure
relatively rare phenomenon in the healthy dog or
was measured based on the number of oscillations ment. Furthermore, hypertension appears to be a
of the blood vessel detected per minute. It is impor- cat. In the healthy pet population with a low inci-
tant for the operator to ensure that the heart rate dence of disease, measuring a high blood pressure
reported at the time of the blood pressure reading is may be more likely to be a false positive measure-
accurate and representative of the patient’s true ment than truly represent hypertension. As a result,
heart rate. If a discrepancy is noted, the blood pres- it is not recommended that healthy cats and dogs
sure measurement should be discarded since the automatically have their blood pressure measure-
unit was not able to accurately distinguish the ment obtained at every appointment.
blood vessel wall oscillations over time. There may be a reasonable argument to measure
Similar to pressures measured using the Doppler blood pressure in a patient periodically (e.g. 2–3
flow method, the first oscillometric measurement years old, 4–6 years old, and 7–9 years old) to
should be discarded and the next five to seven establish a baseline of what may be normal in that
measurements recorded and averaged to deter- patient in the event changes occur which do war-
mine the patient’s blood pressure. The oscillomet- rant blood pressure measurement. Age-related
ric units require less technical skill than the increases in blood pressure have been documented
Doppler ultrasonic equipment and have an advan- in people and a small (<3 mmHg/year) increase in
tage that they may be programmed to cycle at blood pressure has been variably reported in dogs.
pre- determined intervals to obtain oscillometric The relationship between age and blood pressure in
readings over time. cats is not clear based on the current literature.
Regardless of the indirect technique used, many In contrast, there are several organs that are more
studies have illustrated that indirect blood pres- susceptible to damage in patients suffering from
sure monitoring is inconsistent and may not be hypertension, especially if prolonged. This damage is
representative of direct blood pressure readings. often referred to as target organ damage (TOD).
In an effort to reduce variability within a given When an animal exhibits signs of TOD during an
patient, measurements should always be obtained exam, it warrants blood pressure evaluation. Target
consistently. The patient’s position (recumbency), organs include the eyes, central nervous system (CNS),
limb used for measurement, cuff size, and dispos- heart, and kidneys. The most common effect of hyper-
ition should all be recorded to ensure repeat- tension on the eyes is retinal detachment. However,
ability. In addition, the indirect blood pressure hypertension may also manifest as additional changes
monitoring modality used and environment (e.g. in the eye including retinal hemorrhage, retinal blood
with owner, location/room used) should also be vessel tortuosity, retinal edema, hyphema, and retinal
documented. degeneration. Central nervous system changes may be
referred to as hypertensive encephalopathy and can
range from lethargy to seizures, altered mentation, and
2.3 Indications
vestibular changes. Hemorrhage and infarction in the
Which veterinary patients warrant a blood pressure CNS have also been reported. Central nervous system
measurement is not always easily determined and changes are more likely to occur after an acute
there are many factors that contribute to this increase in blood pressure. Cardiac changes in response
debate. In addition, as discussed later, a blood pres- to chronic hypertension include murmurs, gallop
sure measurement that is consistently representa- rhythms, and left ventricular hypertrophy. Chronic
tive of the arterial blood pressure is not easily and hypertension also consistently increases the degree of
predictably obtained. proteinuria or albuminuria in experimental settings
and may contribute to renal damage.
In addition, there are numerous diseases (see
Hypertension
Table 2.2) that have been shown to have an association
When a clinician is concerned about hypertension, with hypertension. Dogs or cats with these diseases (or
it is important to remember that some patients highly suspected of having these diseases) should

36 D.S. Foy