Exam 4 - Systemic Hypertension Flashcards
what is the formula for blood pressure?
BP = HR X SV X SVR
blood pressure is the product of what?
cardiac output & systemic vascular resistance
what is the gold standard for measuring blood pressure? how is it done? what does it measure? is it commonly done?
direct blood pressure measurement - measured via catheterization of an artery & electronic transducer
measures systolic, diastolic, & mean arterial pressure
not commonly done - not practical for screening & management of hypertension
what is the best way to measure blood pressure in cats & small dogs? how is it done?
doppler sphygmomanometry - indirect, non-invasive way to measure
uses the frequency changes between emitted ultrasound & returning echos from moving blood cells or vessel walls to detect blood flow in an artery
why is oscillometry not the best way to measure blood pressure in cats?
it underestimates when blood pressure is high
how does oscillometry measure blood pressure?
microprocessor detects pressure oscillations that result when flow is occluded
what blood pressure reading is used for clinical assessment?
systolic blood pressure
where do you place the cuff for reading blood pressure?
midway between the elbow & carpus
in the tibial region
base of tail
what is the protocol that should be used for measuring blood pressure in a small animal patient?
same individual should take all measurements - allow 5-10 minutes for acclimation, keep patient calm & motionless & not sedated - need to be gently/minimally restrained in ventral or lateral recumbency with the cuff at the base of the heart
discard first measurement - 5-7 consecutive values are recorded & averaged - if they trend down over time, take measurements until plateau is reached & then record 5-7 measurements
written record should include person taking measurements, cuff size & site, values obtained, rationale for excluding any values, & mean result
how is pressure cuff size determined for blood pressure readings? what happens if the wrong size is used?
cuff width should be 30-40% of the limb circumference at the cuff site
if too small - falsely high readings
if too big - falsely low readings
how is doppler used to get blood pressure readings?
good contact between doppler probe & skin achieved with alcohol to dampen hair & plenty of ultrasound gel
inflate cuff 20-40 mmHg above the point where blood flow is no longer heard
what patients should you measure blood pressure on?
in patients with signs of target organ damage
in patients with conditions known to be associated with hypertension
in patients on meds/following toxin ingestion
screening of aging patients
T/F: sighthounds have higher normal ranges of blood pressures than other breeds
true
what were definitions of hypertension developed based off of?
risk of target organ damage
what defines normotensive?
minimal target organ damage risk - systolic blood pressure < 140 mmHg
what defines prehypertensive?
low target organ damage risk - systolic blood pressure 140-159 mmHg
what defines hypertensive?
moderate target organ damage risk - systolic blood pressure 160-179 mmHg
what defines severely hypertensive?
high target organ damage risk - systolic blood pressure > 180 mmHg
in general, hypertension should be documented as persistent for how many occasions?
needs to be documented as persistent for 2 or more occasions
over 4-8 weeks for patients with low or moderate target organ damage risk
over 1-2 weeks for patients with high target organ damage risk
T/F: hypertension with evidence of target organ damage warrants treatment after a single measurement session
true
what is white coat hypertension?
increase in blood pressure that occurs in clinic in a patient that is otherwise normotensive - important to differentiate from true hypertension
how is idiopathic hypertension diagnosed?
diagnosis is suspected when reliable measurements demonstrate persistent increase in blood pressure with a normal CBC, chem panel, & urinalysis
can be difficult to rule out subclinical kidney disease - also hypertension can cause pu/pd
what is secondary hypertension?
> 80% of cases & more common than idiopathic!!!
increased blood pressure due to a concurrent illness, medication, or toxin - hypertension may persist after treatment of the underlying condition
hypertension can occur with any IRIS CKD stage, so is severity of hypertension related to severity of CKD?
nope
what is the pathogenesis of hypertension from chronic kidney disease?
involves sodium & water retention, activation of the RAAS, sympathetic nervous system, & structural changes to arterioles, & endothelial dysfunction
what is the pathogenesis of hypertension in cushingoid dogs?
glucocorticoid induced production of angiotensinogen by the liver & exaggerated sympathetic nervous system response
can cause mild to moderate dose-dependent hypertension
what is the pathogenesis of hypertension in hyperthyroid cats?
may involve increased sensitivity to catecholamines & direct effect of thyroid hormone on cardiac myocytes
what are some toxins associated with causing hypertension?
ephedrine/pseudoepinephrine
cocaine
methamphetamine
5-hydroxytryptophan
T/F: hypertension can cause retinal detachment & acute onset blindness
true