acute kidney injury Flashcards
What is the glomerular filtration rate (GFR)?
Amount of plasma filtered through the glomeruli per unit of time
125-200 ml/min
Directly related to the perfusion pressure in the glomerular capillaries: related to renal blood flow
What are the functions of the kidneys?
Filter blood
Excrete waste
Regulate electrolytes
Regulate pH
Regulate BP
Regulate RBC production
When kidneys are not working, the patient may be anemic
Vitamin D synthesis
What are the characteristics of acute kidney injury (AKI)?
When the kidneys cannot remove the body’s metabolic wastes or perform their regulatory functions
Accumulation of body wastes
Affecting endocrine and metabolic functions
Fluid, electrolyte, and acid-base disturbances
Systemic disease
Metabolic acidosis and fluid electrolyte imbalance
What is the assessment for AKI?
Renal sonogram or a CT or MRI: anatomic changes
BUN level increases dependent on the degree of
Catabolism (breakdown of protein)
Renal perfusion
Protein intake
Medications such as corticosteroids
Serum creatinine: monitoring kidney function and disease progression and increase with glomerular damage
More sensitive than BUN as an indicator of renal function
What are the categories of AKI?
Prerenal, infrarenal, and postrenal
What is prerenal AKI?
Hypoperfusion of the kidney
What percentage of patients with AKI have prerenal?
60-70%
What are the causes of prerenal AKI?
Volume depletion
Impaired cardiac efficiency
Vasodilation
Prerenal ARF
What causes volume depletion?
Hemorrhage
Burns
GI losses (vomiting, diarrhea, NG suction)
Renal losses (diuretics)
What causes impaired cardiac efficiency?
MI
HF
Dysrhythmias
Cardiogenic shocks
What causes vasodilation?
Anaphylaxis
Antihypertensive medications
Sepsis
What causes prerenal ARF?
Lasix/fluid challenge: increased urine output
What could happen if prerenal ARF is not treated promptly?
Ischemia
Necrosis
What is intrarenal AKI?
Actual damage to the kidney tissue
What causes intrarenal AKI?
Prolonged renal ischemia
Nephrotoxic agents
Infectious processes
What causes prolonged renal ischemia?
Pigment nephropathy (associated with the breakdown of blood cells containing pigments that in turn occlude kidney structures)
Myoglobinuria (trauma, crush injuries, burns)
Hemoglobinuria (transfusion reaction, hemolytic anemia)
What are nephrotoxic agents?
Aminoglycoside antibiotics (gentamicin, tobramycin)
Radiopaque contrast agents
Heavy metals (lead/mercury)
Solvents and chemicals (ethylene glycol, carbon tetrachloride, arsenic)
NSAIDs
ACE inhibitors
What infectious processes can cause intrarenal AKI?
Acute pyelonephritis
Acute glomerulonephritis
What is postrenal AKI?
Obstruction to urine flow distal to the kidney
What does an obstruction after the kidney cause?
Pressure rises in the kidney tubules and eventually, the GFR decreases
What causes postrenal AKI?
Calculi (stones)
Tumors
Benign prostatic hyperplasia
Strictures
Blood clots
What could happen after postrenal AKI?
Kidney failure
What are the phases of AKI?
Initiation, oliguria, diuresis, and recovery
What is the initiation phase of AKI?
Begins with the initial insult and ends when oliguria develops
What is the oliguria phase of AKI?
Less than 400ml urine in 24 hours or 0.5 ml/kg/hr of urine output
What electrolyte imbalance happens in the oliguria phase of AKI?
Increase in the serum concentration of substances usually excreted by the kidneys
Urea, creatinine, uric acid, organic acids, intracellular cations (potassium and magnesium)
May develop hyperkalemia: life-threatening
What is the diuresis phase of AKI?
Gradual increase in urine output → GFR has started to recover
What happens in the diuresis phase of AKI?
Lab results stabilize
Urine output may be normal or above normal
Uremic symptoms may still be present
Observed for dehydration
What is the recovery phase of AKI?
Improvement of renal function
Lab values return to normal
How long may the recovery phase of AKI take?
3-12 months
After the recovery from AKI, what percent of GFR is reduced?
1-3%
What may indicate the use of continuous renal replacement therapy (CRRT)?
Those who have an episode of AKI with a pre-existing condition of CKD
What are the lab result findings of someone with AKI?
Hyperkalemia (above 5)
Hyperphosphatemia (above 4.5)
Hypocalcemia (below 8.5)
Anemia (Hct: below 45 in male, below 37 in female)
What is the normal range for potassium?
3.5-5
What is the normal range for phosphate?
2.5-4.5
What is the normal range for calcium?
8.5-10.2
What is the normal range for Hct?
45-52 for male
37-48 for female
What is a hospital-acquired AKI?
Radiocontrast-induced nephropathy (CIN)
How can CIN be prevented?
Prehydration with saline
What is the treatment for AKI?
IV fluids
Transfusions of blood products (albumin)
What can dialysis be used to treat?
Hyperkalemia
Metabolic acidosis
Pericarditis
Pulmonary edema
What are the ECG changes seen in hyperkalemia?
Tall, tented, or peaked T waves
What are the clinical changes associated with hyperkalemia?
Irritability
Abdominal cramping
Diarrhea
Paresthesia
Generalized muscle weakness
What is the treatment for hyperkalemia?
Long-term: kayexalate (polystyrene sulfonate)
Immediate due to hemodynamically unstable: IV dextrose, 50% insulin, and sodium bicarbonate
What is the treatment for severe acidosis?
Sodium bicarbonate and dialysis
What is the treatment for hyperphosphatemia?
Calcium carbonate
What can cause severe nutritional imbalances?
NV
Impaired glucose use and protein synthesis
Increased tissue catabolism
What should be the diet of someone with an AKI?
High carbohydrate meals to spare protein for tissue healing
Avoid foods and fluids containing potassium or phosphorus
High-protein, high-calorie diet during diuretic phase
What is nursing management for someone with AKI?
Monitoring fluid and electrolyte balance
Reducing metabolic rate
Promoting pulmonary function
Preventing infection
Providing skin care
Providing psychosocial support
How can we reduce metabolic rate?
Bed rest: during acute stage of AKI
Treat fever and infection
