indirect measurement of blood pressure Flashcards
what are the two general ways to measure blood pressure?
direct and indirect
what is a direct method of measuring blood pressure?
sensory is in the artery
what are indirect methods of measuring blood pressure?
palpation
korotkoff sounds
doppler
oscillometry
what is the only indirect method that accurately measures diastolic pressure
oscillometry
what do spygmomanometers consist of
rubber back surrounding cuff
manometer to measure bag pressure
inflation/deflation system with rubber bulb and exhaust valve
which is more accurate and informative palpation of ausculatation?
ausculation
what is the usefulness of the palpatory method?
can measure systolic pressure and serves as a useful check
how does blood flow in circulation normally? laminar or turbulent flow?
laminar
what are pathological causes of turbulent flow?
narrowed arteries, stiff or partially closed heart valves
what does turbulence cause?
friction and production of heat
what is reynold’s number?
R=(mean velocitydiameterblood density)/blood viscosity
what happens when reynold’s number is exceeded?
turbulence occurs
when is the Reynold’s number decreased?
when vessels branch or atheroslerosis plaques intrude on the lumen
what are Korotkoff sounds?
they are sounds that are created by turbulent flow in the artery and are used for indirect blood pressure measurement
what is phase I Korotkoff sounds?
sharp sounds
what are phase II korotkoff sounds?
sounds murmurish
what are phase III korotkoff sounds?
sounds loud and thumping
what are phase IV korotkoff sounds?
sounds muffled, diastolic pount
what are phase V korotkoff sounds?
silence
what is doppler measurement of blood pressure?
the doppler probe is placed over the artery distal tothe blood pressure cuff
what is the most common method used to determine blood pressure in a human clinical setting?
oscillometry
what are the principles of measuring blood pressure by oscillometry?
with the cuff inflated there are no oscillations. when the cuff deflates, oscillations appear and amplitude increases to a maximum at mean arterial pressure; oscillations then decrease; the systolic and diastolic pressures are then calculated from the mean arterial pressure
(algorithms differ for different species)
systolic is first major oscillation
diastolic is last major oscillation
where is the cuff placed for oscillometry in the dog and cat
on the tail, measuring the caudal artery
