Kidney Alterations and Acute Kidney Injury (AKI) Vocabulary Flashcards

A set of vocabulary flashcards covering concepts, definitions, classifications, and diagnostic techniques for kidney alterations and acute kidney injury (AKI).

Acute Kidney Injury (AKI)

A reversible syndrome characterized by a rapid loss of kidney function, resulting in a rise in serum creatinine and a decrease in urine output.

RIFLE Classification

A classification tool used to describe stages and outcomes of acute kidney injury, standing for Risk, Injury, Failure, Loss, and End-stage kidney disease.

RIFLE Stage: Risk

The first stage of AKI in RIFLE, defined by an SCr increase of $1.5\text{--}1.9\times$, a GFR reduction of $\neq 25\times$ (or $\neq 25\times$ reduction), or urine output $<0.5\times\text{mL/kg}$ per hour for $6\text{--}12\times\text{hours}$.

RIFLE Stage: Injury

The second stage of AKI in RIFLE, defined by an SCr increase of $2\text{--}2.9\times$, a GFR reduction of $\neq 50\times$, or urine output $<0.5\times\text{mL/kg}$ per hour for $12\text{--}24\times\text{hours}$.

RIFLE Stage: Failure

The third stage of AKI in RIFLE, defined by an SCr increase $\neq 3\times$ or $\neq 4\times\text{mg/dL}$ increase with an acute rise of $\neq 0.5\times\text{mg/dL}$, a GFR reduction $\neq 75\times$, or urine output $<0.3\times\text{mL/kg}$ per hour for $\neq 24\times\text{hours}$ or anuria for $\neq 12\times\text{hours}$.

RIFLE Outcome: Loss

A possible outcome in the RIFLE classification defined by total loss of kidney function for $>4\times\text{weeks}$.

RIFLE Outcome: End-Stage Kidney Disease

A possible outcome in the RIFLE classification defined by total loss of kidney function for $>3\times\text{months}$.

Prerenal AKI

A category of AKI caused by factors external to the kidneys that reduce systemic circulation and decrease renal blood flow, leading to decreased glomerular perfusion and filtration.

Intrarenal AKI

A category of AKI caused by direct damage or injury to the kidney structures themselves, including the tubules, glomerulus, or interstitium.

Postrenal AKI

A category of AKI caused by mechanical obstruction in the outflow of urine, causing urine to back up into the renal pelvis and impair kidney function.

Anatomical Locations of AKI Etiologies

An anatomical cross-section demonstrating prerenal impairment at the renal artery, intrarenal damage within internal structures, and postrenal obstruction along the ureter.

Acute Tubular Necrosis (ATN)

A common intrarenal cause of AKI that can be ischemic or nephrotoxic, resulting from major surgery, shock, ischemia, nephrotoxins, or sepsis.

Oliguric Phase

The stage of AKI characterized by urine output $<400\times\text{mL/day}$, occurring within $1\text{--}7\times\text{days}$ of kidney injury and lasting $10\text{--}14\times\text{days}$ or longer.

Kussmaul's Respirations

Rapid and deep breathing patterns exhibited by patients to compensate for metabolic acidosis during the oliguric phase of AKI.

Diuretic Phase

The stage of AKI where urine output increases to $1\text{--}3\times\text{L/day}$ (up to $5\times\text{L/day}$ or more), placing the patient at risk for hypovolemia, dehydration, hyponatremia, and hypokalemia.

Recovery Phase

The final stage of AKI that begins when the glomerular filtration rate increases, leading to stabilization and normalization of BUN, creatinine, fluid, and electrolyte levels over $1\text{--}2\times\text{weeks}$ up to $12\times\text{months}$.

Ultrasound-Guided Renal Biopsy

A diagnostic technique utilizing an ultrasound probe to guide precise needle placement into the kidney to obtain tissue for identifying intrarenal causes of AKI.

Indications for Renal Replacement Therapy

Clinical indications requiring dialysis or renal replacement therapy in AKI, including severe fluid overload, hyperkalemia, metabolic acidosis, BUN $>120\times\text{mg/dL}$, mental status changes, pericarditis, pericardial effusion, or cardiac tamponade.

Oliguria Assessment Threshold

A urine output of less than $30\times\text{mL/hr}$ for $2\times\text{hours}$ or the presence of dark amber urine, requiring prompt reporting to the healthcare provider.