Renal Assessment Part 2: Kidney Flashcards
Test 3
Where are the kidneys located?
Retroperitoneal
between T12 - L4
Which kidney is slightly caudal? Why?
Right
to accommodate liver
What is the primary functional/structural unit of the kidney?
nephron
Each kidney has about _____ nephrons
1 million
What does the nephron consist of? (6)
-Glomerulus
-Tubular system: Bowmans capsule
Proximal convoluted tubule (PCT)
Loop of Henle
Distal convoluted tubule (DCT)
Collecting duct
The kidney gets ___% of CO which is about _______ L/min
20%
1-1.25 L/min
What is the outer layer of the nephron? Inner layer? How much RBF does each of these layers receive?
outer: Cortex 85-90%
Inner: Medulla 10-15%
what area of the nephron is especially vulnerable to ischemia? Why?
The medulla/LOH
Receive less RBF (10-15%) –> more prone to be affected by hypotension and decreased kidney perfusion
What are the functions of the kidney?
-regulates extracellular, volume, osmolarity, composition
-regulate blood pressure (long-term/ intermediately) via RAAS, ANP
-maintains acid/base balance
-produces hormones (Renin, Erythropoietin, calcitriol, prostaglandins)
-blood glucose homeostasis
EPO is involved in _____ production
RBC
Calcitriol helps maintain __________
serum ca++
Kidneys play a role in ___________ and re-absorption of glucose
Gluconeogenesis
Renal labs define & value: GFR
125 - 140 ml/min
Glomerular filtration rate
Best measurement of renal function over time
How does GFR decrease with age?
After 20yo it decreases by 10 ml/min every decade (10yrs)
Renal labs define & value: creatinine clearance
110 - 140 ml/min
Most reliable measure of GFR
Done over 24 hours
What is GFR heavily influenced by?
Hydration
What is the most accurate measurement of GFR?
Creatinine clearance
Creatinine is freely ________ but not ________ in the kidney.
Freely filtered
Not reabsorbed
Renal labs define & value: serum creatinine
females: 0.6 - 1.3 mg/dL
males: 0.8 - 1.3
of creatinine left after kidney filtered
# should be low
Serum creatinine can be influenced by what?
High protein diet
Protein supplements
Muscle breakdown
Serum creatinine is ________ related to GFR. What does this mean?
Inversely
Decrease SC = increase GFR
In acute cases, double serum creatinine = _______ GFR
50% decrease
Renal labs define & value: BUN
10 - 20 mg/dL
Blood Urea Nitrogen
Shows how well kidneys reabsorbing urea into blood
What effects BUN?
Low: malnourished, Volume diluted
High: high protein diet, Dehydration, G.I. bleed, trauma muscle wasting kidney damage
Renal labs define & value: BUN:Creatinine ratio
10:1
BUN reabsorbed: creatinine not reabsorbed
-Good measure of hydration status
Renal labs define & value: Proteinuria
<150 mg/dL
protein in urine
A proteinuria greater than ______ suggests what?
750 mg/dL
glomerular injury or UTI
Renal labs define & value: specific gravity
1.001 - 1.035
Measures nephrons ability to concentrate urine
-compares 1ml urine to 1ml of distilled water
High specific gravity =
Urine too concentrated
Low specific gravity =
Urine too dilute –> kidney unable to concentrate urine
Drop in UO is a _______ sign of volume loss
late
What is normal UO?
30ml/hr
0.5-1ml/kg/hr
Define oliguria
<500ml in 24 hrs
Beside UO, what are other signs of volume depletion?
Orthostatic pressure changes
Decrease in base access (-2 –> also suggests metabolic acidosis)
Increase lactate
What does a compressed Inferior vena cava (IVC) indicate?
50% collapse = Dehydration
What is SVV?
Stroke Volume variation
Compares inspiratory vs expiratory pressures
-assumes pt ventilated & NSR
What motion can determine fluid responsiveness before administration?
Passive leg raise
What causes an AKI? Patho?
Causes: hypertension/hypovolemia
-nephrotoxins
Can’t excrete nitrogen waste products
-can’t maintain fluid/electrolytes homeostasis
Happens over hours-days
What is the Hallmark symptom of AKI?
Azotemia: buildup of nitrogen products –> urea; creatinine
AKI w/ MSOF requiring dialysis has a ____% mortality
50%
What type of dialysis is used for AKI?
CVVHD
What are risk factors for AKI?
Pre-existing renal disease
-Advanced age
-CHF
-PVD
-DM
-sepsis (hypotension)
-jaundice
-major procedures
-IV contrast
What is the AKI criteria for Dx?
Increase serum creatinine 0.3 mg/dL in 48h or 50% in 7 days
Decrease in creatinine clearance by 50%
Abrupt oliguria
What are physical symptoms of AKI?
Asymptomatic
Malaise
HTN/hypo
increase/decrease volume
What are the 3 different types of AKI?
Prerenal Azotemia
Renal Azotemia
Postrenal Azotemia
What is the most common form of AKI?
Prerenal
Describe Prerenal Azotemia; Tx.
Caused by decreased RBF
Usually reversible
Tx: Restore RBF (Increase BP; restore fluid volume; etc); Fluids, Pressors, mannitol, diuretics
What is the most common cause of ATN?
Prerenal –> renal
What is the lab dx for prerenal AKI?
BUN:Cr > 20:1
Normal is 10:1
Describe Renal Azotemia; S/S; Tx.
Damage to nephrons (intrinsic)
Potentially reversible
S/S: Decreases GFR, urea reabsorption, BUN, creatinine filtration; increased serum creatinine
What is the lab Dx for renal azotemia?
BUN:Cr <15:1
Normal: 10:1
Describe postrenal Azotemia; S/S; Tx.
Outflow obstruction –> increases nephron tubular hydrostatic pressure –> damage nephron & tubular epithelium
Tx: remove obstruction asap
How can you Dx post renal azotemia?
US
Postrenal Azotemia reversibility is ______ related to duration
inversely
(longer obstruction = less likely to be reversible)
What are causes of prerenal Azotemia?
-hemorrhage
-G.I. fluid loss
-trauma
-surgery
-burns
-cardiogenic shock
-sepsis
-aortic clamping
-thromboembolism
What are causes of renal Azotemia?
-acute glomerulonephritis
-vasculitis
-interstitial nephritis
-ATN
-contrast dye
-nephrotoxic drugs
-Myoglobinuria
What are causes of postrenal Azotemia?
-nephrolithiasis
-BPH
-clot retention
-bladder carcinoma
What are the Neuro complications of AKI?
Related to protein/amino acids in blood:
-uremic encephalopathy (improved w/ dialysis)
- mobility disorders
-neuropathies
-myopathies
-seizures
-strokes
What are cardiovascular complications of AKI?
-systemic HTN
-L ventricular hypertrophy
-CHF
-Pulm edema
-uremic cardiomyopathy
-arrhythmias (from increased electrolytes)
-cardiac tamponade
-pericarditis
-anemic heart failure
-ischemic heart disease
What are hematological complications of AKI?
Anemia:
-decrease EPO production –> decrease RBC production
-decrease RBC survival (don’t survive well in uremic environment)
-platelet dysfunction
-vWF disturbed (by uremia) –> DDAVP helps
What are metabolic complications of AKI?
-hyperkalemia
-water/Na imbalances
-hypoalbuminemia
-metabolic acidosis
-malnutrition
-hyperparathyroidism
Why is Vasopressin the preferred pressor in AKI?
Preferentially constricts the efferent arteriole better than alpha agonists for maintaining RBF
What colloid is preferred w/ AKI? Why?
albumin
Natural and not synthetic
You should give _____ prophylactically with AKI. Why?
Sodium bicarb
Decreases formation of free radicals –> prevents ATN from causing renal failure
With AKI, we have a ____ threshold for invasive hemodynamic monitoring
Low
A patient may need ______ postop if they cannot clear drugs on their own
Dialysis
What are the leading causes of CKD? What are the percentages?
DM 38%
HTN 26%
T/F: CKD is progressive but it’s easily reverse
F
It is progressive and irreversible
What is the presentation for CKD?
-Sx for dialysis access
-DM
-toe/foot debridement
-amputations
-non-healing wounds
Describe the stages of CKD (5)
Stage 1: Normal/increased GFR
GFR >90
Stage 2: mildly decreased
GFR 60 - 89
Stage 3: moderately decreased
GFR 30 - 59
Stage 4: severely decreased
GFR 15 - 29
Stage 5: kidney failure
Completely dependent on dialysis
GFR <15
What is the hallmark symptom of CKD? What is this dt?
systemic HTN/fluid overload
This is dt Na/water retention from activation of RAAS
What are the drugs used in Tx for CKD? 1st line?
Thiazide diuretics <– 1st
ACE-I/ARBs
How does ACE-I/ARBs help in CKD? (4)
- Decrease systemic blood pressure
- Decrease glomerular pressure.
- Decrease proteinuria <– glomerular filtration
- Decrease glomerulosclerosis
In CKD, what are the dyslipidemia labs associated with this?
Triglycerides >500
LDL >100
CKD are predisposed to “Silent _____”. What is this?
Silent MI
CKD/DM –> peripheral & autonomic neuropathy –> blunted sensations –> may not feel normal MI pains
Who is more at risk for silent MIs?
Women
DM pts
What is your target hgb in CKD?
10
What are the hematologic effects with CKD? What consideration should we have?
Anemia
Tx: Exogenous EPO
Transfusion can make lead to excessive Hgb –> sluggish circulation –> further decrease perfusion (also acidosis & increased K)
What are indications for dialysis?
-volume overload
-severe hyperkalemia
-metabolic acidosis
-symptomatic uremia
-failure to clear medication’s with metabolites (neuro/respiratory SE present)
PD is ______ than HD. Why does this matter?
slower
HD more efficient/faster
pt may not be able to tolerate HD because of this, may only be able to tolerate PD or CRRT.
What is the leading cause of death in dialysis patients?
Infection dt impaired immune system/healing
You need a pre/post dialysis weight ____ within Sx
24 hrs
What will an A1C tell you that a spot check sugar wont?
A1C can help indentify if there will be long term kidney injury present
How does DM & Obesity effect your anesthesia care plan with CKD?
Affects GI motility –> aspiration precautions
Use US if need to to see gastric contents
May need to RSI
With CKD, what pressors may they not be responsive to? Why?
Neo
Ephedrine
Because of the increasing circulating endogenous catecholamines –> use vaso, NE, epi
CKD causes _____ bleeding. What considerations should we have?
uremic bleeding
-Assess platelet function
-Consider giving cryo, F VIII, vWf to decrease bleeding
-Desmopressin (DDAVP)
DDAVP peaks in _____ and lasts _____. What consideration should I have with this?
2-4 hrs
6-8hrs
Needs to be given early dt prolonged peak time
DDAVP _______ in effect with each use. What is the word for this?
Decreases
Tachyphylaxis
With CKD, what type of drugs do we want to avoid? Why? What are some examples?
Drugs that have active metabolites
Ex) morphine; Demerol
They will accumulate in the system dt not being able to be excreted and cause CNS negative effects
Many anesthetic agents are ______ soluble and our reabsorbed by ________
lipid
Renal tubular cell
What is the best NMB that is not dependent on renal elimination?
Nimbex –> metabolize by plasma esterase
With CKD, drugs that are lipid ______ had a prolong DOA. What consideration should I have with this?
insoluble
Need to use renal dosing based on GFR
What drugs are lipid insoluble and need renal dosing based on GFR with CKD?
Thiazide diuretics
Loop Diuretics
Digoxin
Many abx
What drugs use renal excretion and will stay in the system longer with CKD?
Induction: phenobarbital
Thiopental
Muscle relaxant: pancuronium
Vecuronium
Cholinesterase inhibitors: Edrophonium
Neostigmine
CV drugs: atropine
Digoxin
Glycopyrrolate
Hydralazine
Milrinone
Antimicrobials: Aminoglycosides
Cephalosporins
PCN
Vanc
Liver will eventually metabolize these if functioning properly
What are morphines metabolites?
Morphine-3 glucuronide
Morphine-6 glucuronide
__% of morphine is excreted through urine/kidney
40%
What is the active metabolite of demerol? What does it cause?
Normeperidine
has analgesia & CNS effects
AE: Neurotoxicity –> nervousness, tremors, muscle twitches, seizures
The 1/2 life of Normeperidine is _______ compared to demerol/meperidine which is ________
15-30hrs
2-4hrs
Increasing catecholamines –> activates ________ –> increases _____ateriole constriction –> _____ RBF
Alpha 1-R
afferent
decreases
