Acute Renal Failure Flashcards
Risk factors for Acute Kidney Injury
Age greater than 75
DM
Preexisting chronic kidney dz
CHF
Liver failure
Sepsis
Exposure to IV contrast
Cardiac surgery
anything that reduces renal perfusion
Acute Kidney Injury Definition
abrupt decline (within 48hrs) in kidney function as manifested by: 1.increased serum creatinine
- decreased urine output
- or need for dialysis
Sx of acute renal injury
- *may be asymptomatic**
- N/V
- Malaise
- Altered sensorium
- HTN
- Pericardial effusion, arrhythmias
- pulm edema
- abd pain
- platelet dysfunction
- asterixis
- confusion
- seizures
- all of these are secondary to uremia/azotemia.
Decreased GFR leads to increased BUN in 2 ways, what are those?
- decreased flow through glomerulus
2. slower transport time allows for more BUN to be reabsorbed at the level of the PCT
What leads to increased levels of creatinine in the blood? BUN?
What is Normal BUN/Creat Ratio? elevated?
creat: increased with muscle breakdown (will be increased if greater mass)
BUN: breakdown of proteins
(tetracycline, burns, fever, steroids, GI bleeding)
Normal BUN/Creat = 10-20:1
Elevated: greater than 20:1
What are two mechanisms at the level of the nephron lead to increased serum creatinine?
- blockage at the sites in the DCT that allow for active secretion
- decreased GFR as there is less creatinine present at the glomerulus to be filtered out.
Kidney damage may lead to ____ serum Cr or ____ CrCl
kidney damage may lead to INCREASED SCr or INCREASED CrCl
What are some laboratory abnormalities with acute kidney injury?
- Increased BUN, creatinine
- decreased GFR
- Hyperkalemia
- Hypocalcemia
- Hyperphosphatemia
- Anemia
- Platelet dysfunction
- anion gap metabolic acidosis
Classification of acute kidney injury is based upon where the problem lies, what are the three types?
pre-renal (decreased renal perfusion )
Intrinisic (alteration of normal process within the kidney)
Post renal (inadequate drainage of urine distal to kidney)
Examples of Pre-renal failure
- low Cardiac output; CHF
- Hypotension: shock, sepesis
- Hypovolemia (bleeding. V/D)
- Renal artery stenosis
- Renal artery atheroembolic dz
- decreased glomerular perfusion pressure by dilation of efferent arteriole (ACEi/ARB) or afferent arteriole (NSAIDS)
Low perfusion pressure in prerenal failure, how does the kidney try to compensate?
-increases Na+ reabsorption in an attempt to increase volume. Water follows sodium
What is the urine sodium and urine osmalality be in prerenal failure? BUN/creat ratio? FENa%
Urine sodium is low(less than 20), urine water content is low which makes it very concentrated = high osmolality (greater than 500), high specific gravity (greater than 1.010).
BUN/creat ratio is elevated (greater than 20:1)
Fractional Excretion Na less than 1%
Tx of prerenal?
Treat the underlying cause**
maintain euvolemia and electrolyte balance
avoid nephrotoxic drugs
may require short course of dialysis
Most recover over time
Post Renal Acute Kidney Injury:
- what?
- most common cause
- reversible or not?
- other causes
What: obstruction somewhere in the kidney, ureter, bladder, or urethra.
MC Cause: prostatic obstruction
Reversible
Causes:BPH, Anticholinergic drugs(no shit, no spit, no pee, no see), Cancers, neurogenic bladder, urethral stones or strictures
Post Renal Acute Kidney Injury:
- SIgns and Sx
- Diagnostics
Signs and Sx:
- History is key!
- may or may not have oligura anuria
- flank pain
- low back or abdominal pain
- enlarged prostate or pelvic mass
- distended bladder
- inability to void
Dx:
- bladder ultrasound
- bladder catheterization (diagnostic and therapeutic)
- CT scan of the abdomen and pelvis (renal stones and hydronephrosis)
- Ultrasound of the kidney may show hydronephrosis
