Hypertension Flashcards
what is hypertension?
Persistently elevated BP measured on 3 separate occasions, minimum of 2 days apart, systolic ≥140 and / or diastolic ≥90 mmHg.When severely elevated, minimum of 3 readings on same visit.
NB with correct blood taking techniques :
- Rested patient, seated 5-10 mins, arm at heart level supported.
- correct Size of the cuff. (Upper arm cuff is the most reliable). Wrist cuff or finger pulse not recommended
- correct cuff placement ->over brachial artery,2-3 cm above antecubital fossa
- placed on the bare arm or over a thin sleeve. The patient’s sleeve should not be rolled up, as this may act as a tourniquet, nor should the measurement be taken over a thick sleeve, as this may lead to an overestimate of the patient’s BP.
Even though left side is prefered when taking blood pressure ,Conditions such as aortic dissection do necessitate BP reading rom both arms anda difference in these readings is difference but what is the threshold of this difference ?
The threshold difference is >20mmHg.
describe the pathophysiology of hypertension .
different organs play a part .
Brain ->inappropriaely high sympathetic outflow -> catecholamines ->NE and E ( this then can because the root oof evrything )
Blood vessels -> increased large arterial stiffness (arteriolar sclerosis in old age )->increased systemic resistance
– Abnormal venoconstriction and high venous return .
KIDNEYS :
- inappropriate high renin release
- abnormal renal salt/water handling
explain the mechanism of hypertension
- Blood Pressure = CO Cardiac Output (volume of blood that the body pumps in 1 minute [Stroke volume – volume of blood pumped out of the left ventricle during each systolic cardiac contraction ]
- Heart Rate [number of beats per minute] x PVR [ Peripheral Vascular Resistance] Resistance in the circulatory system that is used to create blood pressure, flow of blood and is also a component of cardiac function
= When blood vessels constrict, this leads to an increase in PVR/SVR this is also called the afterload.
=Preload – volume of blood in the ventricles, determined by venous return.
=Afterload – pressure against which the heart has to pump. - Sympathetic outflow > noradrenaline and adrenaline (alpha 1, B1, Alpha 2, B2).
what is the general approach to management of HTN?
What are the therapeutic objectives in the management of HTN?
Explain the non-pharmacological measures /management .
what are the determinants of BP?
Volume overload/salt overload
⇧ systemic vascular resistance
⇧ central drive to increase BP
⇧ sympathetic nerve stimulation.
BP = CO x PVR
[CO= SV x HR]
BP = SV x HR x PVR
list the hypertension stages
systolic/diastolic
Optimal BP=<120/<80
Normal <130/<85
Prehypertension 130 to 139 /85-89
Grade 1 hypertension (mild)=140 to 159/90 to 99
Grade 2 hypertension (moderate )=160 to 179/100 to 109
Grade 3 hypertension (severe)= >180 />110
Isolated systolic hypertension (grade 1)= 140 to 159 /< 90
Isolated systolic hypertension (Grade 2)=>160/<90
explain the suggested algorithm in HTN management (SA hypertension management algorithm 2015)
STEP1 :
Risk Factor Assessment / Target Organ Damage / Complications.
Levels of the BP:
-
STEP 2:
STEP 3:
STEP4:
Explain the initial choice of antihypertensive treatment or combination
Explain the causes of primary hypertension
Explain the causes of secondary hypertension
Which drugs causes secondary hypertension?explain how .
List the group of drugs used in hypertension
- Diuretics (low ceiling and High ceiling )
- Angiotensin converting enzyme inhibitor (ACEi) and Angiotensin receptor blockers (ARBs)
- Calcium chanel blockers
- Mineralocorticoids antagonists
- Sympatholytic agents
- Beta Blockers
- ALPHA2 recepter agonist - Alpha receptor blocker
7.Vaspdilators
Explain the concept of glomerular filtration,sexcretion,secretion and reabsorption.
Concept of excretion, secretion and reabsorption.
Afferent arteriole -> Glomerular capillaries fenestrated (Filtration) glucose, ions like Na, amino acids, into the Bowmans capsule -> not filtered, out through the Efferent arteriole
2. Filtered reabsorbed into the peritubular capillaries.
3.Some of what was (molecules from the blood not filtered can be secreted (occurs in PCT) from the capillaries into the nephron [antibiotics, toxins, molecules that are in excess].
4. Whatever is not absorbed will be excreted in urine.
what are the 4 sites of Sodium reabsorption
4 sites of Sodium reabsorption:
1. Proximal convoluted tubule – Na+HCO3- cotransporter (65%)
2. Thick ascending limb – Na+K+CL- symporter (25%)
3. Distal convoluted tubule – Na+Cl- symporter (5%)
4. Collecting duct – Na reabsorption/K+-H+ excretion (2-4%)
generally which drugs acts on the different sites of Na+ reabsorption?
4 sites of Sodium reabsorption:
1. Proximal convoluted tubule – Na+HCO3- cotransporter (65%)->Carbonic anhydrase inhibitors and osmotic diuretics
2. Thick ascending limb – Na+K+CL- symporter (25%)-> Loop diuretics
3. Distal convoluted tubule – Na+Cl- symporter (5%)->Thiazides
4. Collecting duct – Na reabsorption/K+-H+ excretion (2-4%)-> Aldosterone antagonist and ADH antagonists.
what is meant by High ceilingg diuretics ?
- Effect of diuresis increases with increasing dose
- Cause substantial diuresis
- Loop diuretics (e.g Furosemide)
what is meant by Low ceiling diuretics ?
- Effect of diuresis flattens with dose increase
-Increased risk of adverse effects ( when you keep increasing the dose you are only increasing the side effects at this point not the effect ) - Thiazide diuretics (e.g Hydrochlorothiazide)