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Cardiorespiratory PBL > PBL 3 > Flashcards

PBL 3 Flashcards

1
Q

Abdominal bruit

A

this is a murmur sound that is generated by turbulent flow of the blood in an artery due to partial obstruction

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2
Q

Renal artery stenosis

A

this is the narrowing of one of the renal arteries due to atherosclerosis, narrowing of the renal artery can impede blood flow to the kidney and result in renovascular hypertension

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3
Q

Angioplasty

A

this is a procedure that is used to widen blocked or narrow coronary arteries, this procedure is done using a balloon to stretch open a narrowed or blocked artery

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4
Q

Occlusion proteinuria

A

this is protein in the urea caused by a blockage or closing of a blood vessel

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5
Q

Creatinine

A

this is a compound that is produced by metabolism of creatine and is excreted by the kidney in the urine

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6
Q

Describe the vascular anatomy of the kidney

A
  • The renal arteries branch of the abdominal aorta and supply the kidneys with blood
  • Arterial supply of the kidneys vary from person to person, and there may be one or more renal arteries supplying each kidney
  • The right renal artery is longer than the left renal artery due to the position of the IVC
  • Renal arteries carry a large portion of the total blood flow to the kidneys
  • ¼ of CO pass to the kidneys and are filtered by the kidneys
  • Renal blood supply starts with the branching of the aorta in the renal arteries and ends with the exiting of the renal veins to join the IVC
  • Renal arteries split into different segmental arteries upon entering the kidneys which then split into several arterioles
  • Afferent arterioles larger diameter than efferent arterioles
  • The afferent arteriole branch into the glomerular capillary which transfer fluid into the glomerulus and into the bowman’s capsule
  • Efferent arteriole takes blood away from the glomerulus and into the interlobular capillaries these provide tissue oxygenated to the parenchyma of the kidney
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7
Q

what is the GFR

A

the GFR is the total amount of fluid filtered through all the glomeruli in both the kidneys

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8
Q

what is the average GFR

A

120-125 ml/min

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9
Q

what is urine flow and why is it different from the GFR

A

Urine flow is amount 1 ml/min – it is different because most of the fluid filtered is therefore reabsorbed

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10
Q

what is GFR used for

A

Used to measure the level of kidney function and determine the stage of kidney disease

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11
Q

what happens if the GFR is below 60 for more than 3 months

A

If a GFR is below 60 for three months or more or a GFR above kidney with damage indicates chronic kidney disease

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12
Q

what happens to the GFR and RPF when the kidneys are damaged

A

If the kidneys are damaged generally the GFR will decrease but the RPF may be normal, measurement of GFR is essential test of kidney health

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13
Q

define clearance

A

Clearance is the effective volume of plasma that is completely cleared of a substance per minute

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14
Q

How do you measure clearance

A
  • used to measure the GFR

- measured in the units volume/time

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15
Q

what are the three outcomes of what clearance equals

A
  1. Not at all removed by the kidney – clearance = 0
  2. Removed at the same rate as water passes through the glomeruli – clearance = GFR
  3. Completely removed from blood passing through kidney – clearance = RPF
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16
Q

what is the clearance formula

A

urine concentration/plasma concentration x urine flow

17
Q

how do you measure clearance of a substance

A
  1. Measure the concentration of the substance in the plasma
  2. Collect urine for a fixed period to get the urine flow ml/min
  3. Measure the concentration of the substance in the collected urine
18
Q

What do you use to measure clearance

A
  • Inulin usually used, it is a polysaccharide and is completely filtered in the plasma and not absorbed
  • Inulin does occur naturally in the plasma so you have to infuse inulin over a period of hours to reach a steady plasma concentration this makes it impractical
  • Creatinine clearance is used to measure GFR, produced naturally by the body and is freely filtered by the glomerulus
  • Creatinine is the product of creatine metabolism
  • 10-20% error margin,
  • Already at a steady state concentration in the blood
  • You can make an approximation just on the blood levels only
19
Q

what is the normal creatinine clearance

A
  • Women 88-128 mL/min

- Men 97-137 mL/min

20
Q

Describe the renin angiotensin arterial system relating to blood pressure

A
  1. Sodium concentration is too low in the distal tubule
  2. This causes macula dense cells to become active they signal to the juxtaglomerular cells which release renin into the blood stream
  3. Renin is an enzyme
  4. Renin passes into the venous blood where it meets the globular protein angiotensinogen which is made by the liver
  5. The renin enzymically splits of a decapeptide angiotensin I from the angiotensinogen precursor
  6. Angiotensinogen I passes through the lungs and is further cleaved by an endothelial bound ACE into an octapeptide angiotensin II
  7. This passes into the artieral blood and in the arterioles it acts on a G protein
  8. This activates phospholipase C and increases calcium concentrations which triggers the constriction of the smooth muscle of the systemic arterioles
  9. Therefore it increases total peripheral resistance and afterload and therefore assuming there is a constant cardiac output it raises blood pressure
21
Q

How does renin release by sympathetic activation

A
  • Sympathetic activation, this is because there are beta receptors on the juxtaglomerular cells, therefore extra vasoconstriction can be produced by increased amount of renin and angiotensin release
22
Q

How does renal stenosis cause hypertension

A
  • Narrowing of the renal artery can impede blood flow to the target kidney resulting in renovascular hypertension
  • Due to local blood flow the kidneys mistake increases in blood pressure of the entire cirucaltory system
  • There is a low GFR which is what the creatinine clearance tells us therefore increased production of rennin and increased production of aldosterone as aldosterone increases reabsorption of sodium which leads to hypernatremia and increased blood volume
  • Increased renin causes increased angiotensin II which causes increased systemic vasoconstriction and increase ADH release
23
Q

what is the definition of renal artery stenosis

A

It is the occlusion (narrowing) of the renal arteries)

24
Q

what are the symptoms of renal artery stenosis

A
  • Low creatinine clearance this means that there is a low gfr
  • Renovascular hypertension
  • High blood urea nitrogen
  • Dizziness
  • Headaches
  • Oedema
  • Proteinuria
  • Might not get any symptoms except for hypertension, this is only realised when it is tested for
25
Q

what are the risk factors of renal artery stenosis

A
  • Dyslipidaemia
  • Smoking
  • Diabetes
  • Female sex
26
Q

what are the causes of renal artery stenosis

A

Atherosclerosis
- Accounts for 90% of all RAS
- This is the build-up of fats and cholesterol and other substances in the artery wall, these harden as they build up
- Reduces the diameter of the renal artery
- Therefore, it increases total peripheral resistance
Fibromuscular dysplasia
- Accounts for 10% of all RAS
- This is when the muscle in the artery wall grows abnormally
- This means that the renal artery can have narrow sections alternating with wider sections giving a beadlike appearance in images of the artery
- This condition is more congenital

27
Q

describe how the blood results are caused

A

170/110 – deterioration in BP control

left abdominal bruit – turbulent blood flow usually
due to an obstruction

hypokalaemia - due to excess aldosterone. Na+/K+
activity increased – so greater loss of K+.

Raised blood urea nitrogen – measure of kidney
function. High levels of blood urea indicate impaired
kidney function.

moderate proteinuria – damage to the basement
membrane due to chronic high blood pressure

kidneys of uneven sizes – ischaemic kidney will be
smaller

28
Q

How do you treat RAS

A

RAS caused by atherosclerosis

  1. antihypertensive therapy and lifestyle modification e.g. lower cholesterol and fats diet
    - statin
    - antiplatelet agent
  2. renal artery stenting and continuation of medical therapy
    - post stent clopidogrel
  3. surgical reconstruction of the renal arteries

RAS caused by fibromuscular dysplasia

  1. antihypertensive therapy and lifestyle modification
    - percutaneous renal artery balloon angioplasty
  2. surgical reconstruction of the renal arteries
    - renal artery stenting and dual antiplatelet therapy
29
Q

what medication is used to treat RAS

A
  1. ACE – block the angiotensin converting enzyme and prevent the formation of angiotensin II, e.g. cptorpil
  2. Diuretics
    - Thiazide derivatives – block sodium chloride transporter in the distal tubule
    - Aldosterone antagonist
    - Loop diuretics
  3. Beta blockers
  4. Calcium channel blockers
30
Q

What lifestyle changes are used to treat RAS

A
  1. maintain healthy weight and lose weight if you are overweight
  2. eat healthy food
  3. limit salt in your diet
  4. be physically active
  5. reduce stress levels
  6. drink alcohol or caffeinated beverages in moderation if at all
  7. don’t smoke
31
Q

How is an angioplasty done

A
  • this is when a stent is placed in the artery in order to widen it therefore increasing blood flow and reducing total peripheral resistance
    1. a small incision in the thigh is made
    2. then they guide a flexible tube called a catheter through the femoral artery into the narrowed renal artery
    3. doctor then inflates the surgical balloon which is on the tip of the catheter and this pushes plaque against the inner walls of the artery allowing for better flow
    4. stent is placed
    5. keeps artery open
    6. balloon is then deflated and withdrawn
32
Q

what does the renin- angiotensin aldosterone system do

A
  • increased TPR
  • increased after load
  • raises blood pressure
    cardiac output = BP/TPR
33
Q

how can the sympathetic activation increase blood pressure

A

Noradrenaline release

Increases Renin and Angiotensin release - due to beta receptors on the juxtaglomerular cells

34
Q

what is aldosterone

A

a mineralocorticoid steroid hormone

- acts on channel protein in the distal convoluted tubule ENac

35
Q

define clearance

A

this is the volume of plasma completely cleared of a substance per minute

36
Q

what are antihypertensive medication

A
  • interrupt function of RAAS - ACE and ARB
    ACEi – Captopril, Ramipril

SE : Dry Cough ! Increased levels of bradykinin →
bronchoconstriction. Also, risk of angioedema.

ARB – Losartan

or

diuretics
- stop sodium and water retention
- Thiazides- Bendroflumethiazide – block Na/Cl in the DCT
- Aldosterone Antagonists – Spironolactone – Potassium
Sparing!
- Loop Diuretics – Furosemide - Na-K-Cl cotransporter in the
thick ascending limb of the loop of Henle

37
Q

why does bradykinin occur with ACE inhibitors

A

Dry Cough – occurs due to increase in bradykinin which causes
bronchoconstriction. ACE is produced in the lungs and will
normally break down bradykinin into non active metabolites.

38
Q

what lifestyle modifications can rose make

A

Improve her diet – reduce salt intake, reduce fatty foods

Stop Smoking

Exercise More

Cardiorespiratory PBL (5 decks)

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