Unit 6 - Cardiovascular system 3 Flashcards
What is MAP?
Mean arterial pressure
- time weighted average of blood pressure
How is mean arterial pressure calculated?
1/3 (Psystolic - Pdiastolic) + Pdiastolic
What is pulse pressure?
The difference between systolic and diastolic blood pressure
What does blood pressure provide?
The driving force to perfuse organs with blood
- determines perfusion pressure
Why isn’t blood pressure uniform throughout the body?
Effects of gravity
- measure at the level of the heart
Cardiac cycle is cyclical
What factors regulate blood pressure?
Short term - autonomic nervous system
Long term - Renin-angiotensin-aldosterone system
What is cardiac output?
Heart rate x stroke volume
How is MAP calculated?
MAP = CO x TPR (total peripheral resistance)
CO = HR x SV
How does the autonomic nervous system regulate blood pressure?
Smooth muscle tone changes total peripheral resistance
Vasoconstriction = increased resistance = increased blood pressure
Arterioles provide greatest contribution to changes in total peripheral resistance
How can the resistance to flow be calculated?
R = 8nL/pi r^4 R= resistance n = viscosity in blood l = vessel length r = vessel radius
How does the renin-angiotensin-aldosterone system control blood pressure?
Angiotensin II causes arteriolar vasoconstriction, increasing the blood pressure
What factors affect blood pressure?
Age
Sex
Population differences
What is the role of the pharmacist in diagnosing and treating hypertension?
- screening those at risk
- increasing public awareness of risk factors
- promoting appropriate lifestyle changes to limit risk
- no immediate perceivable gain
- regular monitoring and refining of medication
- ensuring compliance
What does hypertension increase the risk of?
Stroke
Coronary heart disease
How can the risk of CV be minimised?
Blood pressure < 120/80 mmHg
What is stage 1 hypertension?
Clinic blood pressure is 140/90 mmHg or higher Subsequent ABPM (ambulatory blood pressure monitoring) or HBPM (home blood pressure monitoring) average blood pressure 135/85 mmHg
What is stage 2 hypertension?
Clinic blood pressure is 160/100 mmHg or higher
ABPM or HBPM average blood pressure is 150/95 mmHg or higher
What is severe hypertension?
Clinic systolic blood pressure is 180 mmHg or higher or
Clinic diastolic blood pressure is 120 mmHg or higher
How is hypertension diagnosed?
Measure blood pressure in both arms whilst patient is sitting, relaxed and arm is supported
- repeat if > 15 mmHg difference and use arm with higher reading
Diagnosis of stage 1 or 2 hypertension should follow elevated BP measurements made over several visits and/or addition or ABPM or HBPM (if ABPM not tolerated)
What should be initiated if severe hypertension is observed?
Urgent or emergency treatment
What should be assessed whilst waiting for hypertension confirmation?
Cardiovascular risk
- Qrisk
End organ damage
What is the primary aim of treating hypertension?
Achieving target BP
Reducing risk of CVD
What is primary hypertension?
Essential or idiopathic
- unknown origin
- lifestyle
- genetic factors
Accounts for 95% of cases
What is secondary hypertension?
Elevated blood pressure due to underlying, identifiable cause
Accounts for 5% to 10 % of hypertension in adults.
