Hypertension Flashcards
How can you calculate blood pressure?
BP = CO x peripheral vascular resistance
Define hypotension
A systolic BP <90mmHg and/or diastolic <60mmHg
Define pre-hypertension
SBP 130-139, DBP 85-89. Not a disease and isn’t treated but lifestyle changes encouraged
Define hypertension
When SBP persistently >140mmHg and DBP persistently >90mmHg
Define postural hypotension
If, when standing, systolic BP falls more than 20mmHg or diastolic BP falls greater than 10mmHg; this is associated with dizziness and fainting. More frequent in the eldery and those with diabetes
Define hyponatraemia
Where extracellular fluid sodium levels fall below 135mmol/L (normal is 135-145mmol/L)
What are the risks associated with hypertension?
Increase in stroke, cardiac death and peripheral artery disease
What are the main two mechanisms that control blood pressure?
Baroreceptors in carotid arteries (neuronal system) and the RAAS hormonal system
Explain how baroreceptors work to control blood pressure
Detects changes in blood pressure via stretch receptors in the carotid sinus which activates sympathetic nervous system relay to modify BP
Explain how the RAAS system works to control blood pressure
Low BP causes renin production, and this then activates angiotensin and aldosterone production which causes increased water reabsorption (increased blood volume) and vasoconstriction to increase BP
What is primary hypertension?
Hypertension with no obvious underlying cause
What is secondary hypertension?
Hypertension with a clear underlying case, such as renal disease, endocrine disease, coarctation of the aorta, thyroid dysfunction or iatrogenic causes (due to other drugs)
How may hypertension be treated?
The ladder approach:
- Lifestyle changes
- Thiazide diuretic e.g. Bendroflumethazide
- Thiazide + (beta blocker or ACE inhibitor)
- Angiotensin receptor blocker (ARB)
- Calcium Channel blocker
- Alpha blocker
