Acute Kidney Injury

Question 1

Definition of AKI

Answer 1

-abrupt loss of kidney function that results in the retention of blood urea nitrogen (BUN), creatinine, and metabolic wastes normally excreted by the kidneys.
-Replaces “Acute Renal Insuffiency”

Question 2

Classifications of AKI & UOP

Answer 2

-Anuric: <50 mL urine/24 hours (ex: pts in shock, bilateral urinary tract obstruction, bilateral renal artery obstruction)
-Oliguric <500 mL/24 hours (patients with acute tubular necrosis)
-Nonoliguric >500 mL/24 hours

Question 3

AKI Physical Examination

Answer 3

-ENT: Ulcerations
-Cardiac: Elevated JVP, S3 or S4, pericardial friction rub, peripheral edema
-Respiratory: crackles, pleural effusions, oxygen requirements, pink frothy sputum
-GI: Ascites
-GU: Enlarged prostate, bladder distention, tenderness
-Skin: Poor skin turgor, rash, itch marks

Question 4

Causes of AKI: Prerenal

Answer 4

-Sudden and severe drop in BP (shock), or interruption of blood flow to the kidneys from severe injury or illness
-problem that occurs before perfusion to the kidney, such as decreased perfusion from a lack of blood volume from either bleeding, dehydration, sepsis, hypotension, trauma, heart failure, a problem within the renal artery from a clot or stenosis, dissection
–Drugs: NSAIDs, ACE, ARBS, prograf, cyclosporine, contrast-all change renal perfusion

Question 5

Intrarenal: Causes of AKI

Answer 5

-Direct damage to the kidneys by inflammation, toxins, drugs, infection or reduced blood supply.
-Acute tubular necrosis: Progression of prerenal, kidney may require dialysis, recovery phase may last months, nephrotic exposure (Abx, contrast, chemo, uric acid, tumor lysis syndrome)
–Allergic interstitial nephritis: Medication induced (abx, PPI, NSAIDs)-fever, rash, arthralgia, hematuria
-Acute glomerulonephritis

Question 6

Causes of AKI: PostRenal

Answer 6

-Sudden obstruction of urine flow due to enlarged prostate, kidney stones, bladder tumor, or injury

Question 7

Types of Acute Renal Failure

Answer 7

-Acute Tubular Necrosis — 45%
-Prerenal — 21%
-Acute on chronic renal failure — 13% (mostly due to ATN and prerenal disease)
-Urinary tract obstruction — 10%
89% Prerenal, ATN, or Obstructive Causes
-Glomerulonephritis or vasculitis — 4 percent
-Acute interstitial nephritis — 2 percent
-Atheroemboli — 1 percent

Question 8

Acute Glomerulonephritis

Answer 8

-Inflammation and damage to glomeruli
-Autoimmune causes (lupus, goodpasture, IgA nephropathy)
-Vasculitis (polyarteritis, Wegner’s)