11 - Acute Kidney Injury Flashcards
Azotemia is?
Abnormally high serum levels of nitrogenous substances
- urea
- creatinine
Nitrogen+emia = blood condition
Azotemia = nirogen in blood
Uremia is
Clinical syndrome that results from abnormally high serum levels of nitrogenous substances
Uremia = urine in blood
Azotemia and uremia?
Azotemia -> -> Uremia
Abrupt drop in GFR results in?
Inability to maintain acid/base or fluid/electrolyte balance
Inability to excrete nitrogenous waste
Nonspecific symptoms of AKI/AFR?
Due to azotemia or its underlying cause
- prolonged azotemia can cause uremic syndrome
Urine with AKI or ARF?
Volume
- <400-500 mL/day
- or <20mL/hr
= oliguria
Can also be impaired renal concentration
- high or normal volume
Rarely anuria
Marker for severity with AKI/ARF?
Serum cratnine concentratino increase by 1-1.5 mg/dL/day
As GFR decreasees?
Tubular secretion of Cr increases so
- in early disease stages a large reduction in GFR is necissary to rase serum creatinine
RIFLE criteria?
Risk Injury Failure Loss ESRD
AKI/ARF categories?
- Prerenal causes
- Intrinsic renal disease
- Postrenal causes
1st step toward treating AKI/ARF?
Identifying the cause
MC cause of AKI?
Rerenal azotemia (40-80%)
Cause of prerenal azotemia?
Due to renal hypoperfusion
Why is the prognosis of prerenal azotemia
If reversed quickly w renal restoration of renal blood flow -> renal parenchymal damage is prevented
If hypoperfusion persists -> ischemia -> intrinsic renal injury
Causes of renal hypoperfusion with prerenal azotemia?
- L intravascular volume
- Change in vascular resistance
- Low cardiac output
Basically: Hypovolemia and Shock
Decrease in intravascular volume can be caused by?
- hemorrhage,
- GI losses,
- dehydration,
- excessive diuresis,
- extravascualr space sequestration,
- pancreatitis,
- burns,
- trauma,
- peritonitis
Change in vascular resistance can be caused by?
- sepsis
- anaphylaxis
- anesthesis
- afterload-reducing drugs
- renal artery stenosis
Low cardiac output can be caused by?
- Cariogenic shock
- CHF
- PE
- pericardial tamponade
- arrhythmia
- valvular disorders
prerenal Azotemia + NSAIDS + ACEI can lead to?
Hypovolemia - reduced kidney perfusion
+
NSAIDS - block vasodilatary prostaglandins at Afferent arteriole
+
ACEI - prevent Efferent arteriole vasoconstrition
=
Acute Renal Failure
Pts with prerenal azotemia present with?
Dehydration from renal or extrarenal fluid losses
Labs for prerenal azotemia?
BUN: Creatinine ratio >20:1
H urine osmolality
Urinary sedement - bland or hylaine casts
Una <20 mEq/L
FEna <1%
What lab did he make a huge deal about?
BUN: creatinine ration > 20:1
Be able to calculate it
Differentiates prerenal and intrinsic renal disease?
FE(na) <1%
Tx for prerenal azotemia?
- admit
- achievement of euvolemia
- fix serum electrolytes
- NO NEPHROGENIC DRUGS
- monitor unrine output (should go up)
Least common cause of AKI?
POSTrenal azotemia (5-10%)
Why is it important to detect POSTrenal azotemia?
It is reversible (if you find it)
Its obstructed urinary flow
Pathophys of Postrenal azotemia?
Obstruction
- > H intraluminal pressure
- > parenchymal damage
- > L GFR
Causes of postrenal azotemia?
Obstruction of both ureters/renal pelvises
Bladder dysfunction/obstruction
MC cause of urethral obstruction in men?
BPH
Other causes of postrenal azotemia?
- anticholinergic meds
- cancer
- retroperitoneal fibrosis
- ## neurogenic bladder
Less common causes of postrenal azotemia?
- blood clots
- bilateral ureteral stones
- urethral stones/stricture
- bilateral papillary necrosis
Presentation of postrenal azotemia?
Anuria or Polyuria
Lower abd pain
PE for postrenal azotemia?
Enlarged prostate
Pelvic mass
Distended bladder
Labs for postrenal azotemia?
- BUN:creatinine ratio >20:1
- H urine osmolality -> later L urine osmolality
- urine sediment: bland (benign)
- Fe(na) variable
- U(na) variable
Tx for postrenal azotemia?
- Admit
- bladder catheterization
- find cause (US, CT, MRI)
- correct obstruction
- postobstructive diuresis
After relieving long-term bladder outlet obstruction beware of?
Postobstructive diuresis -> hypovolemia
After pre and post renal causes are excluded look at?
Intrinsic renal disease
Sites of injury that cause intrinsic renal disease?
- tubules
- interstitium
- vasculature
- glomeruli
Acute tubular necrosis (ATN) =?
AKI/ARF due to tubular damage
- 85% of intrinsic AKI/ARF
Major causes of ATN?
Ischemia
Nephrotoxin exposure
What is ischemic ATN?
Tubular damage due to low perfusion -> tubular necrosis and apoptosis
- begins as prerenal azotemia
Ischemic ARF is characterized by?
Inadequate GFR
Inadequate renal blood flow
- inability to maintain parenchymal cellular perfusion
Ischemic ATN occurs?
In the setting of prolonged HOTN or hypoxemia
- (volume depletion, shock, trauma etc)
Nephrotoxic ATN causes?
Exogenous (MC)
Endogenous
Exogenous nephrotoxins?
Aminoglycosides Vanc Amphotericin B IV acyclovir Cephalosporins Radiographic contrast Cyclosporine Antineoplastics Heavy metals
Endogenous nephrotoxins?
Heme-containing/mimicking products - myoglobin (rhabdo) - hemoglobin (intravascular hemolysis) Uric acid (hypouriecmia) - rapid cell turnover and lysis (chemo) Paraproteins - bence jones protein (multiple myeloma)
ATN presentation?
Gen swelling N/V Oliguria Signs of Hypovolemia decreased LOC Anorexia Gi bleed Muscle weakness/twitching
ATN labs?
Active urine sediment - muddy brown cysts - renal tubular epithelial cysts/casts Urine output: oliguric/nonoliguric BUN:creat <20:1 UA(na) >20 FE(na) >1-2% Hyperkalemia Hyperphosphatemia (Common)
Tx for ATN
Admit ICU Avoid volume overload - dieuritics - monitor pulmonary edema Mantai fluid electrolyte and acid/base - avoid hyperK Nutritional support - protein restriction Dialysis
ATN tx indication for dialysis
Life-threat electrolyte disturbancy Volume overolad unresponsive to diuretics Worsening acidosis Uremic complications - encephalopathy, pericarditis, seizures
3 phases (clinical course) of ATN?
Initial injury
Maintenance (1-3 wks or months)
Recover - heralded by diuresis
Mortality with ATN?
Varies 20-70%
Causes
- infection
- fluid/electrolyte disturbances
- worsening underlying disease
Acute interstitial nephritis (AIN) essentials for diagnosis?
Fever Transient maculopapular rash Acute renal insufficiency Pyruria (eosinophils) - WBC casts Hematuria
Causes of AIN?
Drugs (70%)
Infectious diseases
Idiopathic conditions
Full list on 41
AIN presentation
Fever (80%)
Rash
Arthralgias
Peripheral blood eosinophilia (80%)
Classic triad of AIN?
Fever
Rash
Arthralgias
10-15% of cases
AIN labs?
Bun:creat <20:1 UA - RBC - WBC - WBC casts - eosinophiluria Proteinura Peripheral blood smear: eosinophilia
AIN tx?
– Nephrology consult
– Supportive measures
– Removal of inciting agent
– If renal failure persists → short course of steroids
– Good prognosis w/ recovery usually w/in weeks-months – Acute dialysis therapy may be necessary in 1/3 of
patients
• Rarely progress to ESRD
Vascular ARF causes?
Renal vein thrombosis
Renal infarction
Malignant HTN
Acute glomerulonephritis and AKI/ARF?
Uncommon cause - 5%
Essentials for diagnosis w acute glomerulonephritis?
hematuria
- dysmorphic RBC
- RBC casts
- mild proteinuria
Dependent edema and HTN
Acute renal insufficiency
Intrinsic renal disease comparison?
Slide 46
Might be a good one
Homeopathic surgery
“Quick nurse, hand me nothing”
