Renal Response to CPB- Exam 1 Flashcards Preview

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Flashcards in Renal Response to CPB- Exam 1 Deck (56)
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1

What does the kidney do?

Regulates fluid composition, intravascular volume and excretion of metabolic byproducts

2

What is the incidence of renal failure (i.e. requiring dialysis)

Decreasing; 1%

3

Why is the incidence of renal failure decreasing?

Better patient preparation
Improved perfusion techniques
better management cardiac performance post op

4

If renal dysfunction occurs, what is the mortality rate?

>50% mortality rate

5

What is the function unit of the kidney?

Nephron

6

How many nephrons in each kidney?

More than 1 million

7

What are the two main parts of the nephron?

Glomerulus
Tubular system

8

What is the glomerulus?

Specialized capillary network
Allows filtration of fluid from plasma (no cellular components or proteins)

9

Glomerular membrane vs. normal capillaries

100x more permeable than normal capillaries

10

Tubular system

Collects filtered fluid
alters composition converting plasma filtrate to urine

11

What is the normal Glomerular Filtration Rate

100-200 mL/min in normal adult; preserved over a broad range of blood pressures

12

What percent of the volume filtered is reabsorbed (osmotic diffusion)?

99%

13

How is urine output related to arterial blood pressure?

Linear increase in output with increase in arterial blood pressure

14

If you increase pressure 100 to 200 mmHg urine output increases by factor of what?

7

15

Decrease blood pressure below 50 mmHg causes what?

Urine output to stop

16

What allows long term control of blood pressure?

Urine output

17

What determines how concentrated or dilute the urine is?

ADH

18

ARF Risk in patients with valve surgery vs. CABG

Patients undergoing valve surgery twice the risk compared to CABG patients

19

What is the most significant risk factor for acute renal failure?

Preoperative renal dysfunction

20

How can you determine preoperative renal dysfunction?

Elevated serum creatinine
Decreased creatinine clearance

21

What are some other risk factors for acute renal failure?

Impaired cardiac function
Complexity of procedure
Advanced age
genetics

22

ARF-D develops in what percent of patients?

1.2 to 13% of patients post CPB

23

Intraoperative Renal Risk Factors

Low flow
Decreased blood volume
IABP
Prolonged CPB times with SIRS
Inappropriate hemodilution
Emboli
Avoiding hypothermia
Pulsatility

24

High Hematocrit results in

Decrease in microcirculatory blood flow

25

Low hematocrit results in

Decrease in renal oxygen-carrying capacity

26

What lowers organ metabolic requirements?

Hypothermia

27

What is hte most important target in hypothermia?

Brain

28

Stroke & Renal failure at 37C vs 34C?

Strokes and renal failure occured more frequently at 37C than 34C; difference not statistically significant

29

What is the difference in plasma renin activity or concentration of vasopressin?

No difference in plasma renin activity or concentration of vasopressin 37C vs 34C

30

What happened to renal clearance and other indices of renal function while on bypass with warm heart surgery?

Transient increase in renal clearance returned to normal after bypass; temp had no lasting effect