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
