Acute Kidney Injury Flashcards
Definition of AKI
Abrupt loss of kidney function that results in the retention of BUN, creatinine, and metabolic wastes normally excreted (Replaces acute renal insufficiency)
Classification of AKI & UOP: Anuric
<50mL urine/24 hours
-Patients with CKD, shock, bilateral urinary tract obstruction, bilateral renal artery obstruction
Classification of AKI & UOP: Oliguric
-<500mL/24 hours
-More likely to have acute tubular necrosis
Classification of AKI & UOP: Non-oliguric
> 500ml/24 hours
AKI Hx & ROS
-Fatigue, infectious symptoms
-oral/nasal ulcers, vision changes
-edema, weight gain/loss, HF hx, recent hypotension, chest pain
-SOB, Cough, sputum production
-intake amount, n/v, appetite, diarrhea, liver disease hx
-urine color, output amount, dysuria, stone hx, urgency/hesitancy, frequency
-Itching
-cramping, myalgia, arthralgia, trauma
-Confusion, asterixis, mental status changes, LOC changes, headaches, seizures
-Anemia, bleeding
–Rashes, fevers.
-Ask about any new OTC and prescribed meds?
-Any contrast administration?
-any chronic comorbid conditions-DM, HTN, stones, recurrent UTIs, vascular disease, cancer?
AKI Physical Exam
-Htn or HOtn
-ulcerations: ent
-Elevated JVP, S3 or S4 sounds, pericardial friction rub, peripheral edema
-Crackles, signs of pleural effusions, o2 requirements, pink frothy sputum
-ascites
-enlarged prostate, bladder distention,
-Rashes, poor skin turgor, itch marks,
-cramping, weakness
-asterixis, altered LOC,
-signs of bleeding, petechial rash
Prerenal AKI
-Sudden and severe drop in BP (shock), or interruption of blood flow to the kidneys from severe injury or illness
Intrarenal AKI
Direct damage to the kidneys by inflammation, toxins, drugs, infection, or reduced blood supply
-Medication induced (abx, nsaids, PPI)-fever, rash, athralgia, hematuria-allergic interstitial nephritis
-ATN
-Acute glomerulonephritis
Post renal AKI
-Sudden obstruction of urine flow due to enlarged prostate, kidney stones, bladder, tumor, or injury
Types of acute renal failure
-ATN-Leading
-prerenal
-Acute renal failure, chronic renal failure
-Urinary tract obstruction
-glomerulonephritis or vasculitis
-atheroemboli
-acute interstitial nephritis
Acute Tubular Necrosis
-intrarenal or intrinsic causes
-nephrotic exposure
-Abx, contrast, chemo, myeloma, uric acid, tumor lysis syndrome
Acute Glomerulonephritis
-Intrarenal
-inflammation and damage to glomeruli
-autoimmune causes (lupus, IGA, goodpasture, nephropathy)
-vasculitis (polyarteritis, wegners)
-infectious causes (strep, endocarditis, HIV, HEP B/C
Initial eval & dx
-Electrolytes-mag, phos, Ca
-ABG
-CXR-Volume overload
-Baseline creatinine level, BUN, bicarbonate
-+/- ultrasound
-Post void residual
Creatinine
-Byproduct derived from the metabolism of creatine in skeletal muscle and from dietary meat
-Affected by age, gender, race, muscle mass, protein intake
-12–24-hour lag behind of kidney damage
-Small increase in creatinine level may represent larger decrease in GFR
Cystatin C
-Measurement of kidney function
-less influenced by muscle mass or diet
-results affected by inflammation and atherosclerosis
-Expensive
-Estimates still being studied on age, race, and gender
Stage 1 of AKI
-Increase in SCr by by ≥0.3 mg/dL
-or ≥1.5 - <2.0 x baseline
-UOP: Less than 0.5 mL/kg per hour for more than 6 hours
Stage 2 of AKI
-Increase in SCr by ≥2.0 - <3.0 times baseline
-UOP: Less than 0.5 mL/kg per hour for more than 12 hours
Stage 3 AKI
-Increase in SCr by ≥3.0 times baseline
-Less than 0.3 mL/kg per hour for 24 hours or anuria for 12 hours
GFR in CKD
-Normal kidney function – GFR above 90mL/min/1.73m2 without proteinuria
1) CKD1 – GFR above 90mL/min/1.73m2 with evidence of kidney damage
2) CKD2 (Mild) – GFR of 60 to 89 mL/min/1.73m2 with evidence of kidney damage
3) CKD3 (Moderate) – GFR of 30 to 59 mL/min/1.73m2
4) CKD4 (Severe) – GFR of 15 to 29 mL/min/1.73m2
5) CKD5 Kidney failure - GFR less than 15 mL/min/1.73m2 or on dialysis, however many patients in CKD5 are not yet on dialysis.
Diagnostic testing: UA
appearance, osmolality, specific gravity, eosinophils
Dx testing: Urine chemistry
Sodium, creatinine, urea (only if on diuretics)
Dx testing: UA with microscopy
Cells, casts, crystals, bacteria, nitrates
What do Feurea and Fena tell us?
-Helps to differentiate between prerenal and ATN
-BUN, Cr, Urine Urea, Urine Cr – diuretics
-Na, Cr, Urine Na, Urine Cr – no diuretics
FeUrea + diuretics, FeNa - diuretics
FeX = (urine x/ serum x)/ (urine Cr/serum Cr) x 100
FeNa > 1% in ATN, < 1% in prerenal
FeUrea > 50% in ATN, < 35% in prerenal
Dx Testing Prerenal
-Urine specific gravity: >1.018
-Urine sodium: <10mEq/L
-FeNa: <1%, FeUrea: <35%
-Urine Osmo: >500 mOsm/L
-Urine sediment: normal, hyaline casts
Dx testing of ATN
-Urine specific gravity: 1.010
-Urine Na: >30-40 mEq/L
-FeNa: >1%
-FeUrea: >50%
-Urine osmo: 280 mOsm/L
-Urine Sed: Renal tubular cells, epithelial, granular casts, muddy brown
Urine Microscopy Interpretation
-WBC- UTI or asymptomatic
-Eosinophils- AIN (acute interstitial nephritis)
-Epithelial cells- contaminate
-RBC- UTI, Malignancy, Traumatic Cath
f/u dipsticks with microscopic exam
-Gram Stain- presence of bacteria
-Contaminant if polymicrobial growth
Urine Microscopy Interpretation: Casts
-RBC—vasculitis, glomerulonephritis
-WBC—Interstitial nephritis, pyleonpehritis
-Epithelial– ATN, AIN
-Waxy—Advanced renal failure
-Hylaine—normal in concentrated urine or diuretic use
-Fatty—heavy proteinuria (Nephrotic syndrome)
-Granular—”muddy brown”, ATN
—-High amount of protein in urine may consider a 24 hour urine collection
Renal US
-Reserve for ordering when concerned about hydronephrosis or prerenal failure not improving with conservative measures
r/o hydronephrosis
Swelling of kidney, obstruction of urine due to anatomy, stone, prostate, clots
-Kidney size: Normal is 10-13 cm
-r/o abscess, cyst
-CT stone protocol to r/o stone
-Doppler measurement for flow of renal arteries and veins
-May not be needed if CT Abdomen/pelvis performed
Management of High Risk AKI
-D/c all nephrotoxic agents when possible
-ensure volume status and perfusion pressure
-consider functional hemodynamic monitoring
-monitor serum creatinine and UOP
-Avoid hyperglycemia
-consider alternatives to radiocontrast procedures
Management of AKI: Stage 1
-D/c all nephrotoxic agents when possible
-ensure volume status and perfusion pressure
-consider functional hemodynamic monitoring
-monitor serum creatinine and UOP
-Avoid hyperglycemia
-consider alternatives to radiocontrast procedures
-Non-invasive dx workup
-Consider invasive dx workup
Management of AKI Stage 2
-D/c all nephrotoxic agents when possible
-ensure volume status and perfusion pressure
-consider functional hemodynamic monitoring
-monitor serum creatinine and UOP
-Avoid hyperglycemia
-consider alternatives to radiocontrast procedures
-Non-invasive dx workup
-Consider invasive dx workup
-check for changes in drug dosing
-consider renal replacement therapy
-consider ICU admission
Management of AKI Stage 3
-D/c all nephrotoxic agents when possible
-ensure volume status and perfusion pressure
-consider functional hemodynamic monitoring
-monitor serum creatinine and UOP
-Avoid hyperglycemia
-consider alternatives to radiocontrast procedures
-Non-invasive dx workup
-Consider invasive dx workup
-check for changes in drug dosing
-consider renal replacement therapy
-consider ICU admission
-avoid subclavian catheters if possible
Renal Diet
-60 grams of protein (more restricted than CKD)
-90 meq low sodium
-60 meq potassium
-800-1000 mg phosphorus
+/- fluid restriction
Hyperkalemia Tx
-Ca Gluconate 1.5-3g IV over 2-5 minutes: stabilizes cardiac membrane, prevents arrhythmias: K >6.5
-Insulin 10 u R & D50W
5-10 units IV insulin in 50 mL D50W (25 g) infused over 15-30 min— K >5.5
-Albuterol 10-20 mg over 10 min vs. 2.5 mg—K >5.5
-Sodium polystyrene sulfonate (Kayex)
15-30 grams PO: K >5.5
-Lasix
Hypermagnesia
-Rare problem unless renal failure
–Level 4-6 meq/L–nausea, flushing, headache, lethargy, drowsiness, and diminished DTs
-Level 6-10-somulence, absent DTs, hypotension, bradycardia
-Level >10-muscle and respiratory paralysis, heart block, cardiac arrest
Hyperphosphatemia
-Long term effects of CAD, calciphylaxis, secondary hyperparathyrodism and hypocalcemia
-Initiation of phosphate binders
Calcium-containing phosphate binders. (Calcium Acetate)
Non-calcium containing phosphate binders (Sevelamer)
Hemodialysis Removes
-Salicylates (ASA)
-Theophylline
-Lithium
-Isopropanol (rubbing alcohol)
-Methanol and ethylene glycol
Medications induce metabolic acidosis
Metformin
Medications associated with urinary retention
-Antidepressants
-Antiarrhythmics
-Anticholinergics
-Antiparkinson meds
-Antipsychotics
-Muscle relaxants
-Narcotics
-Antihistamines
Rhabdomyolysis is associated with
-Trauma or crush injuries
-Prolonged immobilization
-Vigorous exercise
-Compartment syndrome
-Use of statins
-Prolonged seizures
Diagnostic Testing of Rhabdomyolysis
-Creatinine Kinase (CK)
-AKI w/ CK levels-15,000-20,000
-Urine myoglobin
Treatment for Rhabdomyolysis
-Hyperkalemia, hypocalcemia,
-hyperphosphatemia, hyperuricemia
-Hyperkalemia – tx as previously discussed
-Hyperuricemia – Allopurinol
-Hydration – 100-200 ml/hr
-Lasix if volume overload
-Continue until CK level is < 5,000
Cardiorenal Syndrome Type 1
-Acute HF leads to worsening kidney function
Cardiorenal syndrome type 2
Chronic HF leads to progressive chronic kidney disease
Hepatorenal Syndrome
Associated portal hypertension, cirrhosis, ascites, SBP
Type 1 – twofold increase in Cr w/ level >2.5 mg/dL in < 2 weeks, UOP < 500 ml/24 hrs
Type 2 – less severe Cr reduction w/ ascites that is diuretic resistant
Hepatorenal Syndrome: Clinical Features
Diagnosis of exclusion
Decompensated liver disease
Progressive rise in Cr > 0.3 mg/dl
Benign urine sediment
No or minimal proteinuria < 500 mg/24 hrs
Low Na excretion - < 10meq/L
Oliguria
Hepatorenal syndrome tx
-Improvement in liver function etiology
-Improves with transplantation
ICU
Norepinephrine to raise MAP
Albumin IV x 48 hours 1 g/kg per day
-General:
Midodrine 7.5 to 15 mg by mouth TID
Octreotide-continuous IV 50 mcg/hr) or Subq (100 to 200 mcg TID)
Albumin 1g/kg/24 hrs x 48 hrs
-Consider TIPS procedure
Nephritic & Nephrotic Syndrome
-Collection of symptoms that indicate damage to the glomeruli, not a separate disease
Glomerulonephritis PHAROAH Pneumonic
-P: Protein
-H: Hematuria
-A: Azotemia
-R-RBC casts
-O-Oliguria
-A-Anti-strep titers
-H-Hypertension
