Acute Kidney Injury Overview

Study Notes

AKI is a sudden deterioration in the kidneys' ability to maintain fluid, solute, or electrolyte homeostasis.
Causes of AKI are categorized as pre-renal, intrinsic, and post-renal.
- Pre-renal: Hypovolemia (e.g., vomiting, diarrhea, hemorrhage), decreased effective circulating volume (e.g., cardiac failure, septic shock, cirrhosis), and medications (e.g., ACE inhibitors).
- Intrinsic: Glomerular diseases (e.g., glomerulonephritis, glomerular endothelium, vasculitis, hemolytic uremic syndrome (HUS), malignant hypertension), tubular diseases (e.g., acute tubular necrosis, rhabdomyolysis, myeloma), and interstitial nephritis.
- Post-renal: Obstructions (e.g., renal calculi, retroperitoneal fibrosis, prostatic hypertrophy, carcinoma, cervical carcinoma, urethral stricture, bladder/pelvic neoplasm, retroperitoneal neoplasm).
There are specific criteria for diagnosing AKI, which often involves assessing GFR (glomerular filtration rate) and urine output.
A classification/staging system for AKI may be used to stage the severity. Different stages have different creatinine criteria and urine output criteria.
Treatment strategies for AKI are tailored to the cause. Strategies may include restoring blood volume (pre-renal), correcting electrolyte imbalance, discontinuing nephrotoxic drugs (intrinsic), or relieving obstructions (post-renal).

CKD is defined as abnormalities of kidney structure or function for more than three months.
Risk factors for CKD are hypertension, diabetes mellitus, autoimmune disorders, age, and African ancestry.
- Other risk factors include family history of renal disease or previous episodes of acute kidney injury.
- Proteinuria or abnormal urine sediment, or structural abnormalities of the urinary tract may also indicate potential CKD.
GFR is a key indicator of kidney function. A normal GFR in young adults is approximately 125 mL/min/1.73 m2. A GFR of less than 15 mL/min/1.73 m2 is considered kidney failure.
Estimation of GFR (eGFR) can be conducted using equations like the Cockcroft-Gault equation or the Modification of Diet in Renal Disease (MDRD) study equation.
Different stages of CKD are defined based on GFR levels. The stages are numbered, from 1 (least severe) to 5 (most severe). The criteria for staging are based on GFR values in mL/minute per 1.73 square meters. Stages of CKD are typically reflected as a progressive decline in function.
Evidence of kidney damage may be present, separate from low GFR numbers. This can include specific pathologies of the tubules, vessels, or glomeruli, in addition to potential problems arising if there has been a kidney transplant. Other signs may also be considered, such as abnormalities in urinary albumin excretion or urinary sediment abnormalities.

Identification, diagnosis (Renal), assessment of progression.
Monitoring GFR, Blood pressure (BP) control, management of Cardiovascular Disease (CVD) risk, use of ACE/ARB (Angiotensin-converting enzyme inhibitors/Angiotensin receptor blockers).

Blood pressure targets for different clinical CKD situations may be recommended, including use of specific medications.

Glycemic control improves outcomes in people with diabetes.
Recommended target HbA1c is 7.0% to prevent hypoglycemia and delay progressions in microvascular complications of diabetes.

Maintain euvolemia (proper blood volume) via adjusting dietary salt intake and use of diuretics.
Address and remedy specific electrolyte imbalances, such as hyponatremia and hyperkalemia.

Sterile techniques (hand washing, protective equipment, and masks are recommended).
Monitor the site for infection (redness, pus, odor).
Check patency by palpating for thrills and auscultating for bruits.
Evaluate for puncture-site pain and numbness.

Ensure hemodynamic monitoring during RRT.
Administer anticoagulants and monitor for clots and air in the extracorporeal circuit.
Encourage patient activity as clinically appropriate.
Maintain medication timing.

Patient education on vascular access care and blood pressure (BP) measurement techniques, avoiding harmful procedures, and reporting specific issues.
Importance of follow-up appointments for ongoing and changing health needs.
Referral to home healthcare to support care at home.