1. Acute kidney injury AKI

NUR 325 Week 11

• Acute kidney injury (AKI)

Answer

• May be referred to as acute renal failure (older term)

• Abrupt decline in kidney function leading to

• Increased serum creatinine and/or
• Decreased urine output
• Usually develops over hours to days with progressive elevations of BUN, creatinine & potassium

with or without oliguria (urine output <400 mL/24 hrs or <30 mL/hr)

• 3 categories of AKI

• Pre-renal (occurs before the kidneys)

causes that lead to renal hypoperfusion (ex. hypovolemia)

• Intra-renal

causes that affect the renal tissue directly (intrinsic)

• Post-renal

involves obstruction of the urinary tract; problem w/ urine leaving (after leaving the kidneys)

• Pre-renal AKI and hypovolemia

Answer Related to factors that reduce renal blood flow leading to decreased glomerular perfusion and filtration

• Most common cause is hypovolemia (ex. hypotension) 1 / 3

a) Causes decrease in CO, which causes ->

• Release of angiotensin II and aldosterone, which leads to sodium & water retention ->
• Decreased urine output ->
• Decreased filtration leads to accumulation of waste products in the blood (azotemia)

a) Azotemia refers to elevated creatinine & blood urea nitrogen

• Other pre-renal causes of AKI

Answer

• Vasoactive medications

a) Ex. ACE inhibitors, ARBs, epinephrine, dopamine

b) Cause renal vasoconstriction -> hypoperfusion of the glomeruli

• NSAIDs and radiocontrast agents

a) These medications can cause renal vasoconstriction leading to hypoperfusion of the glomeruli

*AKI associated with pre-renal causes is usually reversible *Pre-renal AKI can progress to intra-renal disease if not corrected (must be given fluids to reverse pre-renal AKI

• Intra-renal causes of AKI

Answer

• Conditions that cause direct damage to the renal tissue

• Causes include

• Acute tubular necrosis (most common cause)

• Glomerulonephritis

inflammation of the glomerulus

• Vascular causes

ex. renal vein thrombosis or renal infarction - obstruct the kidney

• Interstitial disease 2 / 3

infection of the interstitial tissue (such as from infection, or tumor growth)

• Nephrotoxins

Answer things that are toxic to the kidneys such as radiocontrast agents, some antibiotics (aminoglycosides, gentamicin, tobramycin), NSAIDs

• Acute tubular necrosis causes

Answer Primarily due to

• Ischemia (#1 cause)

less blood and oxygen delivered to the nephron -> causes epithelial cells that line the tubules to be damaged or destroyed, causing them to slough off -> can create an obstruction -> decreases GFR and increases pressure in tubules -> oliguria develops b/c less fluid can get through -> products that normally get excreted get reabsorbed

• Nephrotoxins

directly damage epithelial cells in the tubules, causing the same process in ischemia to occur

• Acute tubular necrosis can be reversible if

Answer

• Ischemia is not prolonged and is stopped

• Basement membrane of the glomerulus is not destroyed
• Tubular epithelium regenerates

• Post-renal causes of AKI

Answer

• These involve an obstruction of urinary outflow (involving ureters, bladder, urethra)
• / 3