Workshop3: Blood pressure control Flashcards
What is blood pressure?
The driving force to circulate blood around the body
generated from the heart
There are two phases of the cardiac cycle so BP is reported as two numbers. The Systolic pressure and the Diastolic pressure
What is intermittent ejection of blood balanced by?
constant loss from arterial system to capillaries
What is the relationship between MABP and systolic and diastolic pressure?
MABP = Diastolic + 1/3(Systolic-Diastolic)
How is Blood pressure controlled?
By hormones and peptides like ANP, Angil, Aldosterone etc
By mechanistic control MABP=COxTPR
What effects CO?
Stroke volume and heart rate (CO=SVxHR)
What affects SV?
Cardiac contracility, preload and afterload
What affects TPR?
Blood vessels tone
atherosclerosis
arterial stiffening (which increases with age)
What causes korotkoff sounds?
Turbulence of the blood causes vibrations. This occurs as systolic blood pressure is large enough to momentarily open the artery
How is blood pressure measured?
Place cuff snugly around upper arm at same vertical height as heart. Make sure subject is seated and arm is supported
Inflate cuff until brachial artery is completely occluded (~180mmHg) no sounds should be heard
Use air valve to slowly release pressure by 1-2mm/s
SYSTOLIC:
When systolic BP in artery is greater than cuff pressure blood slowly flows to the arm through partially collapsed artery. Korotkoff sounds are heard. The bloodflow is turbulent so these can be heard with a stethscope
DIASTOLIC:
As cuff pressure is reduced the sounds increase in intensity then become mottled and disappear as normal blood flow is re-established. the point of disappearance = diastolic BP
Why is the bell of the stethescope used instead of the diaphragm?
It minimises the effect of room noise and picks up low frequency sounds
What is Auscultation?
Using a stethoscope and a sphygomomanometer
