What is blood pressure?
Blood pressure is the force of blood against the walls of blood vessels
Recorded as two numbers:
Blood pressure Terminology
•Mean Arterial Pressure
–MAP = Diastolic + 1/3 Pulse pressure
average Blood pressures
Factors involved in maintaining BP
••Elasticity of the arteries
ØSuction during inspiration
The volume of blood ejected from the left ventricle into the aorta each minute.
Cardiac Output (CO) = Stoke Volume (SV) x Heart Rate (HR)
In a typical resting adult male, cardiac output is CO
(4.9 l/min) = 70 x 70 = 4900ml/min
•Blood pressure also depends on the total volume of blood in the cardiovascular system.
•Normal blood volume is approx 70ml/kg lean body mass in an adult and 80ml/kg in children
•Therefore 70ml/kg x 70kg = 4900ml
•It is usual to round this up to approx 5 litres
(can increase by up to 50% during pregnancy)
Control of blood pressure
Short term regulation:
Long term regulation:
Some factors that increase blood pressure
•Sedentary or inactive lifestyle
•Heavy alcohol consumption
•Obesity and overweight
Some factors that decrease blood pressure
•Abnormal heart rhythms
••Antidepressants, such as amitriptyline
•Some allergic reactions
••Calcium channel blockers
How to obtain a Blood Pressure
•Locate brachial pulse in antecubital fossa (ACF)
•Place correctly sized cuff
•Palpate radial pulse
•Feel pulse disappear
•Place diaphragm of stethoscope on previously located brachial pulse in ACF
•Release pressure listen for sounds
Pulse pressure is the difference between Systole and Diastole e.g.
•BP = 120mmHg :- Pulse Pressure = ?