3/2/2014
ACUTE KIDNEY INJURY A Hospital-Based Approach to Evaluation and Management
Kristen Lindamen MMs, PA-C Mayo Clinic Arizona
Zachary Hartsell MPAS, PA-C Wake Forest Baptist Medical Center
OBJECTIVES
ö 1. Define and classify renal damage based on the RIFLE Criteria
ö 2.Identify most common precipitants of acute kidney injury
ö 3.Discuss with patients and families the most common complications and prognosis of acute kidney injury
NO DISCLOSURES
1 3/2/2014
ACUTE KIDNEY INJURY
ö Incidence
ó 3-7% of hospitalized patients.
ó 25-30% of ICU patients
ö Sudden decline in renal function (GFR) ó Failure to excrete metabolic waste products
ó Inability to maintain fluid and electrolyte balance
ó Impaired acid-base regulation
DIAGNOSTIC CRITERIA
ö Risk Injury Failure Loss End stage (RIFLE) ó Utilizes serum creatinine and urine output
öSurrogates for GFR ö Acute Kidney Injury Network (AKIN) ó Also based on serum creatinine levels and urine output ó Captures small changes in serum creatinine ö Both used for diagnosis
DIAGNOSTIC CRITERIA
Kidney International Supplements; 2012.
2 3/2/2014
STAGING
ö Staging
ó Risk RRT ó Mortality
ó Long-term risk (after resolution)
öChronic kidney disease
öCardiovascular disease
öMortality
ö RIFLE or AKIN acceptable ó Highest stage
CLASSIFICATION
How much urine produced ö Oliguric <500ml/24 hour ö Nonoliguric >500ml/24 hour ö Anuric <100 ml/24 hour
What causes the injury ö Pre ö Intra ö Post
PRERENAL
ö Hypoperfusion of kidney
ó Volume depletion
öTrue
öEffective
ó Vasoconstriction
ó Hepatorenal
3 3/2/2014
TRUE VOLUME DEPLETION
ö Hemorrhage ö Renal
ó Diabetic ö GI ketoacidosis
ó Vomiting ó Addison ’s disease
ó Diarrhea ö Cutaneous
ó Burns ó Pancreatitis ó Sweating
EFFECTIVE VOLUME DEPLETION
ö Decreased effective circulating volume
ó Normovolemia ó Hypervolemia
ö Vasodilation
ó Sepsis
ó Third spacing
VASOCONSTRICTION
ö Renal vasoconstriction
ó Often medication-induced
öNSAIDs: Afferent arteriolar vasoconstriction
öACE-I/ARBs: Efferent arteriolar vasodilation
4 3/2/2014
INTRARENAL
ö Glomerular
ö Vascular
ö Interstitial
ö Tubular (85%) Most Common
TUBULAR
ö Ischemic ó Hypotension ó Sepsis
ö Nephrotoxic ó Medications öAminoglycosides, Amphotericin B, Cisplatin, Contrast ó Cast nephropathy öMultiple myeloma ó Rhabdomyolysis
CONTRAST NEPHROPATHY
ö Second leading cause of renal failure in hospitalized patients
ö Caused from renal tubular epithelial cell toxicity and renal medullary ischemia.
ö Risk factors include: Diabetes, age, preexisting renal disease, volume depletion, CHF, repeated doses of contrast
5 3/2/2014
CONTRAST NEPHROPATHY
ö Prevention ó Hydration is the Key!
ó Acetylcysteine
ó Sodium Bicarbonate
POSTRENAL
ö BPH
ö Obstruction
ó Bladder outlet obstruction
ó Stones ó Crystals
ó Tumors ó Clots
ó Retroperitoneal fibrosis
EVALUATION
ö Serum Creatinine
ö Normal Range (Adult) ö Male (0.6 – 1.2 mg/dL) ö Female (0.5 – 1.1 mg/dL)
ö Greater than 4mg/dL = serious renal impairment
Creatinine GFR 2 X normal 1/2 normal 3 X normal 1/3 normal 4 X normal 1/4 normal 5 X normal 1/5 normal
6 3/2/2014
BLOOD -PRIMARY EXAMS
ö BUN
ö Electrolytes
ö CBC with differential
ó Eosinophils
ö Phosphorus
BLOOD- SECONDARY EXAMS
ö Antistreptococcal Ab
ö Hep B & C Ab
ö ANA
ö ANCA
ö Anti-GBM Ab
ö Cryoglobulins
ö Complement levels
URINE
ö Urinalysis
ö Urinary sediment- Pathognomonic
ö Random electrolytes
ö Eosinophils
7 3/2/2014
URINE
ö Spot urine protein/ Creatinine ratio ó Nearly as accurate as 24 hour urine
ó Early morning sample best
ó Normal <30mg/g
FEN A
ö Fractional Excretion of Sodium (FENa)
UNa x PCr
ö FENa % = x 100 PNa x UCr
ö <1% suggests prerenal etiology
ö >3% more suggestive of intrarenal (ATN)
BLOOD AND URINE STUDIES
Type of BUN/ Urine Urinalysis Urine Proteinuria Urine Fractional renal Creat Osmolality Volume Na+ excretion failure ratio Na+ Prerenal >20:1 >500 Normal Decreased Trace < 20 <1% mOsm/kg MEq/dL
Intrinsic <20:1 250-300 Dark Oliguric or 2+ - 4+ >30 >3% mOsm/kg granular nonoliguric MEq/dL casts Postrenal <20:1 > 400 Hyaline Absent* 0 - Trace < 20 mOsm/kg casts MEq/dL
8 3/2/2014
RADIOLOGY
ö Ultrasonography ó Safe ó Relatively inexpensive ó Rule out
ö Obstruction
ö Stone
ö Cyst or mass
ö Infection
ö Little value in CT or MRI ó CT may be useful if retroperitoneal fibrosis ó No gadolinium with GFR<30
ROLE OF BIOPSY
Rarely needed to diagnose Acute Kidney Injury ö Indications ó Unexplained CKD/ worsening AKI ó Nephrotic syndrome ó Acute nephritic syndrome
ö Contraindications ó Solitary native kidney ó Bleeding diathesis ó Hydronephrosis ó Pylonephritis ó Renal Tumor
MANAGEMENT
ö Optimization volume status, hemodynamics
ö Renally dosed medications
ö Avoidance nephrotoxins
ö Nutritional support
9 3/2/2014
MANAGEMENT
ö Electrolytes
ó Hyperphosphatemia
ö Bleeding disorders
HYPERKALEMIA
ö Normal range vary
ö No specific number to start treatment ó Based on clinical findings ó Urgency based on EKG findings
ö Three treatment principles ó Stabilize cardiac membranes ó Drive extracellular potassium into cells ó Remove excess potassium from body
HYPERKALEMIA
ö Stabilize cardiac membranes ó IV Calcium
ö Drive extracellular potassium into cells ó Glucose/Insulin ó Beta 2- adrenergic agonist ó Sodium bicarbonate (controversial use)
ö Remove excess potassium from body ó Diuretics ó Cation exchange resins ó Dialysis
10 3/2/2014
INDICATIONS FOR DIALYSIS
ö A: Acid-base disturbance
ó Metabolic acidosis
ö E: Electrolyte abnormalities
ó Hyperkalmia with EKG changes
ö I: Ingested toxins
ö O: Overload refractory to diuretics
ö U: Uremia
ó AMS, Seizure, Pericarditis
WHAT IS DIALYSIS
ö Dialysis refers to the diffusion of small molecules down their concentration gradient across a semi- permeable membrane.
ó Diffusion- movements of small particles down their gradients
ó Ultrafiltration- removal of water from a patients circulation
ROLE OF NEPHROLOGIST
ö In general earlier is better ó CKD model
ö ICU patients ö Patients needing dialysis ö Patients possibly needing biopsy
11 3/2/2014
OUTCOMES
ö Overall mortality 20-90%
ö Postoperative
ó 18-47% develop
ó In-hospital mortality 60-80%
CAUSES OF DEATH IN ACUTE KIDNEY INJURY
ö Infections (30-70%)
ö Cardiovascular events (5-30%)
ö GI, Pulmonary or Neurologic complications (7-30%)
ö Hyperkalemia or Dialysis related (1-2%)
SPECIAL CASES
12 3/2/2014
REFERENCES
ö Coresh, J. et. Al. Prevalance of kidney disease in united states. JAMA 2007;298, 2038-2047. ö Hauser, A. et. Al. Characteristics and causes of immune dysfunction related to uremia and dialysis. Peritoneal Dialysis International, Vol. 28 (2008), Supplement 3. ö Graves, J. Diagnosis and Management of chronic kidney disease. Mayo clinic proceedings. Vol. 83 no. 9 1064-1069. 2008 ö Kidney Disease Improving Global Outcomes. Clinical Practice Guideline for Acute Kidney Injury. Kidney International Supplements. 2012;2:1-138. Available from: http://www.kidney- international.org . Accessed February 16, 2014. ö Kidney Disease Improving Global Outcomes. Clinical Practice Guideline for Acute Kidney Injury. Kidney International Supplements. 2012;2:1-138. Available from: http://www.kidney- international.org . Accessed February 16, 2014.
öKidney and urologic Diseases Statistics of United States, April 2010. National Kidney and Urologic Diseases Information Clearing house (NKUDIC). http://kidney.niddk.nih.gov/kudiseases/pubs/kustats/ . Accessed January 3, 2011. öKao, et. Al. Life expectancy, expected years of life lost and survival of hemodialysis and peritoneal dialysis patients. J Nephrol 2010; 23(06): 677-682. öLam AQ, Seifter JL. Assessment and Management of the Renal Patient. In: McKean SC, Ross JJ, Dressler DD, Brotman DJ, Ginsberg JS. Principles and Practice of Hospital Medicine. New York, NY: McGraw-Hill; 2010: 378-393. öMurphree DD, Thelen SM. Chronic Kidney Disease in Primary Care. J Am Board Fam Med 2010; 23:542–550.
ö Sharfuddin AA, Weisbord SD, Palevsky PM, Molitoris BA. Acute Kidney Injury. In: Taal MW, Chertow GM, Marsden PA, Skorecki K, Yu ASL, Brenner BM. Brenner and Rector ’s The Kidney. 9th ed. Philadelphia, PA: Elsevier Saunders; 2012: 1044-1099. ö Sprangers B, Evenepoel P, et al. Late Referral of Patients With Chronic Kidney Disease:No Time to Waste. Mayo Clinic Proceedings. 2006. 81(11):1487-1494 ö Tonelli et.al. Chronic kidney disease and mortality: a meta- analysis. J Am Soc Nephrol 2006. 17: 2034–2047.
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