Lippincott Nursing Pocket Card - April 2022

Acute Kidney Injury

Formerly known as acute renal failure, acute kidney injury (AKI) is a reversible rapid reduction in glomerular filtration rate (GFR) or kidney function, resulting in an increase in serum blood urea nitrogen (BUN), creatinine, and metabolic waste products (Okusa & Rosner, 2022). If left untreated, AKI can lead to reduced urine output, fluid retention, volume overload, and chronic kidney disease.

Definition (Kellum & Lameire, 2012)

The Kidney Disease: Improving Global Outcomes (KDIGO) organization (Kellum & Lameire, 2012) defines AKI as any of the following:

Increase in serum creatinine (SCr) by greater than or equal to 0.3 mg/dL (25.6 µmol/L) within 48 hours
Increase in SCr greater than or equal to 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days
Urine volume less than 0.5 mL/kg/hour for 6 hours

Classifications of Acute Kidney Injury (Lippincott Advisor, 2022)
	Prerenal	Intrarenal (Intinsic)	Postrenal
Pathophysiology	Decreased blood flow to kidneys	Structural injury that causes vessel constriction within the kidney	Blockage along the urinary tract obstructing urine outflow from the kidney
Causes	Injury or trauma to the back Massive fluid loss (vomiting, diarrhea, bleeding, or dehydration) Systemic vasodilation and hypotension caused by sepsis, anaphylaxis, anesthesia, drug overdose	Acute tubular necrosis Coagulation defect Malignant hypertension Infection and inflammation Leukemia, lymphoma Medications (antibiotics, nonsteroidal anti-inflammatory drugs)	Kidney stones Blood clots Hematoma Prostate enlargement Fibrosis tumors Genetic anatomic narrowing

Contrast-induced AKI (CI-AKI) (Kellum & Lameire, 2012)

CI-AKI may occur in patients who receive iodinated radiocontrast for procedures. Patients should be screened for risk factors such as: advanced age, diabetes, hypertension, congestive heart failure, chronic kidney disease, volume depletion, hemodynamic instability, concurrent nephrotoxic medication use and use of large volume and/or high osmolality contrast agents. To minimize risk, consider these strategies:

Consider alternative methods of imaging studies.
Use low dose iso-osmolar or low-osmolar contrast medium through an intravenous (IV) route.
Begin IV fluids (isotonic sodium chloride or sodium bicarbonate) at least one hour before administration of contrast media and continue for 3 to 6 hours after administration to achieve urine output greater than 150 mL/hour in 6 hours.

Signs and Symptoms

AKI may not produce signs or symptoms until other organs are affected (Dihn, 2020). Signs and symptoms depend on the cause or complications of AKI.

Common Signs and Symptoms of AKI (Lippincott Advisor, 2022)
Shortness of breath	Tachycardia	Arrhythmias
Nausea	Hypertension	Muscle cramps
Vomiting	Weakness	Seizures
Edema (abdomen, extremities)	Tiredness	Oliguria or nonoliguria

Diagnosis (Lippincott Advisor, 2022)

Laboratory Tests

Electrolytes: sodium, potassium, calcium, chloride, phosphorus, bicarbonate
Blood glucose
Albumin
Blood urea nitrogen (BUN) and creatinine
Urinalysis
Complete blood count

Imaging

Ultrasound of kidneys and perirenal structures – detects kidney tissue damage, kidney stones, urinary tract obstruction, or other abnormalities
Computed tomography (CT) scan
Renal angiography – examines the blood vessels

Diagnostic Procedures

Electrocardiography (ECG) to assess for arrhythmias related to electrolyte imbalance
Kidney biopsy to test for malignancy

Stages of Acute Kidney Injury

Stages of AKI (Kellem & Lameire, 2012; Palevsky, 2021)
Stage	CLINICAL MANIFESTATIONS
1	Any of the following: SCr increased 1.5 – 1.9 times baseline SCr increased greater than or equal to 0.3 mg/dL (26.5 µmol/L) Urine output reduced to less than 0.5 mL/kg/hour for 6 – 12 hours
2	Any of the following: SCr increased 2.0 – 2.9 times baseline Urine output reduced to less than 0.5 mL/kg/hour for 12 hours or more
3	Any of the following: SCr increased 3.0 times baseline SCr increased greater than or equal to 4.0 mg/dL (353.6 µmol/L) Urine output reduced to less than 0.3 mL/kg/hour for 24 hours or more Anuria for 12 hours or more Initiation of renal replacement therapy In patients less than 18 years, decrease in estimated GFR to less than 35 mL/min per 1.73m²

Complications (Okusa & Rosner, 2022)

The following complications require immediate kidney replacement therapy (KRT)/dialysis.

Pulmonary edema
Hyperkalemia
- For any serum potassium greater than 6.5 mEq/L
- Hyperkalemia associated with cardiac arrhythmias or muscle weakness
- Hyperkalemia greater than 5.5 mEq/L associated with tissue breakdown or significant gastrointestinal bleeding
Signs of uremia, such as pericarditis, seizure, or unexplained change in mental status
Severe metabolic acidosis (pH less than 7.1) and hypervolemia
Acute poisoning (i.e., metformin, methanol, ethylene glycol)

Treatment

The goal of therapy is to prevent life-threatening complications and limit further damage to the kidneys (Dihn, 2020). Treatment of AKI is mainly supportive, to preserve volume homeostatis and correct biochemical abnormalities.

Treat the underlying cause.
- Manage hypotension; administer vasopressor to improve renal perfusion.
- Correct volume depletion in patients with vomiting, diarrhea, hypotension, tachycardia, or oliguria
  - Avoid fluid therapy in patients with pulmonary edema or anuria.
  - Administer 1-3 liters crystalloid (preferably buffered) followed by maintenance isotonic fluids at 75 mL/hour for volume responsive patients.
- Urology and/or interventional radiology consultation for patients with hydronephrosis due to urinary tract obstruction.
Prioritize glycemic control and nutritional support.
- Target plasma glucose between 110 and 149 mg/dL.
- Restrict salt intake.
- Low potassium, low phosphate diet.
- Recommend high-calorie diet; start enteral feeding as soon as possible to decrease risk of stress ulcer, gastrointestinal bleeding, or hemorrhage.
Administer medications.
- All medications should be reviewed, and dose adjusted based on GFR.
- Diuretics are recommended only to manage volume overload (i.e., 80-100 mg IV furosemide) in patients who are not anuric; unless the patient requires fluid overload management, diuretics are not recommended to treat AKI.
- Vasodilators do not show improvement for AKI patients; dopamine, fenoldapam, and/or natriuretic peptides are not recommended as treatment to improve kidney function.
- Replenish electrolytes and treat acid-base imbalance, as ordered.
- The following medications can worsen AKI. Discuss discontinuing these agents with the healthcare provider.
  - Nonsteroidal anti-inflammatory drugs (NSAIDs)
  - Angiotensin-converting enzyme (ACE) inhibitors
  - Angiotensin receptor blockers (ARBs)
  - Nephrotoxins (aminoglycoside antibiotics, pipercillin-tazobactam, amphotericin B, tenofovir, nephrotoxic chemotherapy)
Institute kidney replacement therapy (KRT) as ordered.
- KRT is indicated immediately for life-threatening changes in fluid, electrolyte, and acid-base balance.
- For patients with volume overload who have anuria for more than 24 hours, who fail to respond to diuretics, or whose response to diuretics is not enough to avoid worsening hypervolemia, KRT is also indicated.
- Types:
  - Hemodialysis (intermittent) is recommended for patients that can tolerate a rapid removal of toxins.
  - Continuous renal replacement therapy (CRRT) is recommended for hemodynamically unstable patients.
  - Peritoneal dialysis is rarely used for AKI.
- The recommended dialysate buffer solution is bicarbonate to correct acidosis, reduce lactate levels and improve hemodynamic stability.
- Anticoagulant therapy is recommended to prevent clotting of the filter.
  - For intermittent KRT with low risk for bleeding, use unfractionated or low-molecular weight heparin.
  - For CRRT with bleeding risk, regional citrate anticoagulation is recommended; if citrate is contraindicated, use heparin.
  - If heparin-induced thrombocytopenia (HIT), discontinue all heparin and use a direct thrombin inhibitor, or Factor Xa.
Surgery
- Insertion of vascular access port as needed for dialysis.
  - Choice of access is uncuffed, non-tunneled catheter
  - Choice of vein in order of preference: right jugular vein, femoral vein, left jugular vein and subclavian vein
- A nephrostomy tube or ureteral stent may be needed to relieve obstruction especially in patients with sepsis due to urinary tract infection.
- Kidney transplant for ESRD

Nursing Interventions

Monitor vital signs including pulse oximetry.
Perform daily weights.
Insert an indwelling bladder catheter to monitor urine output.
Calculate intake and output each shift or more frequently in ICU.
Assess lung sounds.
Monitor level of consciousness and neurologic examination.
Assess for edema.
Keep head of bed elevated, unless contraindicated.
Administer IV fluids as ordered to patients with AKI due to prerenal factors such as dehydration.
Ensure fluid restriction and/or administer diuretics as ordered for patients with volume overload.
Maintain continuous cardiac monitoring; assess for rhythm changes that may signal hyperkalemia (bradycardia, peaked T waves).
Encourage a low sodium, low potassium diet.

References

Dinh N. (2020). Acute kidney injury: Challenges and opportunities. The Nurse practitioner, 45(4), 48–54. https://doi.org/10.1097/01.NPR.0000657324.33611.12

Kellum, J. A. and Lameire, N. (2012, March). KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney International Supplements, Volume 2, supplement 1. https://kdigo.org/guidelines/acute-kidney-injury/

Lippincott Advisor (2022, January 7). Teaching about diseases and conditions: Kidney injury (acute). Lippincott Advisor. https://advisor.lww.com/lna/document.do?bid=31&did=1092377&searchTerm=acute%20kidney%20injury&hits=kidney,injury,acute,kidneys,acutely,injuries

Okusa, M.D. & Rosner, M.H. (2022, February 1). Overview of the management of acute kidney injury (AKI) in adults. UpToDate. https://www.uptodate.com/contents/overview-of-the-management-of-acute-kidney-injury-aki-in-adults

Palevsky, P.M. (2021, February 9). Definition and staging criteria of acute kidney injury in adults. UpToDate. https://www.uptodate.com/contents/definition-and-staging-criteria-of-acute-kidney-injury-in-adults

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Acute Kidney Injury