L12: Hypertension And Hypotension Interventions Flashcards
What are the values to diagnose hypertension
140/90 +
What are advised to individuals who are just above the hypertension value
Change lifestyle such as through diet exercise, alcohol and smoking
What is the equation for arterial blood pressure (ABP)
ABP=CO X TPR
Therefore to decrease ABP what can we do
Decrease CO
Decrease TPR
In normal situations what is involved to control the blood pressure
Baroreceptor reflex
Renin angiotensin and aldosterone
Autonomic control by heart and vessels
What increases the cardiac output
Increased SV
Increased HR
How can we increase SV to increase CO
Increase venous return by venous constriction
Or increase pre-load volume by increasing blood volume
How can we increase the HR
Increase contractility by:
Decreasing PNS via vagus nerve
Increase SNS via pre/post ganglionic fibres
How can we increase TPR
Arterial constriction
What causes arterial constriction
SNS activity
Angiotensin 2
What guideline do we use to determine the treatment for hypertension
NICE guidelines
What are the characteristic of 2 groups that are split into for treating hypertension
Individuals younger than 55 years old
Individuals older than 55 years old or are African/Caribbean
What is the first line of treatment of class of drug to treat individuals younger than 55 years old with hypertension
Class A
What are class A drugs also known as
ACE inhibitors
Name ACE inhibitors
Lisinopril
Enalopril
What is the role of ace inhibitors
To inhibit the enzyme ACE which usually converts angiotensin 1 to angiotensin 2
Angiotensin 2 causes arterial vasoconstriction and increases the TPR
What is the role of ACE with bradykinin
ACE usually causes the degrading of vasodilator kinins such as bradykinin
When we use ACE inhibitors what happens to the levels of bradykinin
Increase
How does the ace inhibitor by acting to reduce angiotensin 2 also reduce venous return and CO as well as causing arterial constriction
1) Angiotensin 2 is required in making aldosterone
2) Aldosterone causes salt and venous retention
3) With ace inhibitors aldosterone is not produced so venous return decreases as water and sodium become excreted.
What are the side effects of ACE inhibitors
Dry cough
Sudden hypotension with diuretics
Why is there a dry cough with ACE inhibitors
Bradykinin increases deposits in the lungs causing a dry cough
Name another class A drug
Angiotensin 2 receptor antagonist
What is the mechanism of action of AT2 receptor antagonists i.e ARBs
It bins to angiotensin 2 receptors so angiotensin 2 cannot bind to cause its effect
What does ARBs cause
Reduces arterial constriction and causes a decrease in TPR
Does ARBs allow the production of aldosterone
Yes because they only block the effect of angiotensin 2 on the vessels not on aldosterone
How does ARBS reduces venous return
By acting on AT2 receptors on venous so it reduce constriction so venous return is decreased as veins are not squished to pump blood to the heart.
When are ARBs used
When ACE inhibitors are not tolerated by the patient
Wha are the 2 classes of drugs used to treat patients with hypertension who are over 55 years old and/or are African/Caribbean
Class C
Class D
What are class C drugs
Calcium channel blockers
What is the mechanism of action of calcium channel blockers
To block calcium channels in smooth muscles in the blood vessel as and therefore stop them from contracting
This reduces TPR
What are the side effects of calcium channel blockers
Affect the GIT activity by decreasing it
What are class D drugs
Diuretics
Where do diuretics act on
The kidney nephron
What is the mechanism of action of diuretics
Increase sodium and water excretion in the urine
This decreases the blood volume
Decrease in blood volume decreases stroke volume and therefore co.
What is the 2nd mechanism of diuretics
Diuretics can result in arterial vasodilation which decreases TPR.
As sodium is depleted calcium also become depleted so smooth muscles cannot contract.
What are the side effects of diuretic
Hypokalaemia
When do we use drugs that affects the SNS in hypertension
As a step 4 line treatments (very last option)
Name a drug that decreases the SNS activity
Beta adrenoceptor antagonist
Name a beta blocker
Propanolol
Atenolol
What is the mechanism of action of beta blockers
Reduce CO by reducing contractility
Decrease renin secretion and therefore angiotensin 2 os vasoconstriction cannot occur and this decreases TPR
What are the side effects of beta blockers
Bronchospasm due to beta 2 receptors in the lungs
Excercise intolerance
Name another drug that affects the SNS activity
Alpha 1 adrenoceptor antagonist
Name an alpha 1 antagonist
Prazosin
Doxazosin
What is the mechanism of action of alpha 1 adrenoceptor antagonist
Blocks alpha 1 receptors so vasoconstriction cannot occur
This decreases TPR
What are the side effects of alpha 1 adrenoceptor
Postural hypotension
What are the 2 options when people get worsening hypertension despite them being on a drug
Increase the dose
Combine therapy
How do combine class drugs
Combine them that covers the 2 types E.g A+C A+D C+D
Why might hypotension occur
Haemorrhage
Burns
Shock
How do we treat shock
Give adrenaline
How do we treat chonic hypotension
Increase salt intake.
