Acute Kidney Injury

Question 1

What are the 3 causes of acute renal failure?

Answer 1

• Pre renal (functional; HYPOperfusion)
  
  • Decreased renal perfusion w/o cellular injury
• Renal-intrinsic (structural; renal tissue)
  
  • Acute Tubular Necrosis (ATN; 90%)
  • Acute Interstitial Necrosis (AIN)
  • Glomerulonephritis (GN)
  • ARF despite perfusion & excretion (check urinalysis, FBC, autoimmune screen)
• Post renal (obstruction)
  
  • Blocked outflow (check bladder, catheter, & ultrasound)

Question 2

What are some lab findings seen w/ patients w/ ARF?

Answer 2

• Rising K, creatinine/urea (cr. clearance r vs. GFR)
• Decreasing Hb and acidosis (would also see a rise in K+ lvls)
• Hyponatraemia & hypocalcaemia

Question 3

What level do creatinine levels need to be for the patient to be considered to be in acute renal failure?

Answer 3

An increase in 50% of serum creatinine levels would be indicative of acute renal failure. Normal range is from 0.5-1.5, however renal failure may be suspected once levels reach 1.5.

Question 4

What are the 3 phases of ARF and describe what occurs in each phase.

Answer 4

1. Initiating - Begins hours to days after event ends when renal injuries occur, reversible at this stage, MAP should be maintained above 70, oxygenation and hydration is key to aid in preventing further injury.
2. Maintenance - Hyperkalemia, lowest phase of urine output (<500ml/24hr), fluid volume overload, at risk for infections
3. **Recovery - **Slow process of tissue repair, urine output starts to increase, may be excessive

Question 5

What are some clinical manifestations of ARF?

Answer 5

• Dehydration (During the diuretic phase)
• Anemia (decreased erythropoietin)
• Pt. appears critically ill & lethargic
  
  • thinking and talking slow
  • weak and fatigued

CNS Manifestations (due to the electrolyte imbalances, hyperkalemia)

• Drowsiness
• HA
• Muscle twitching
• Seizures

Question 6

What are ways to prevent ARF from developing?

Answer 6

• Provide adequate hydration - This is very important for pts. going through procedures with contrast dyes or getting chemotherapy because these agents are nephrotoxic
• Prevent & treat shock/hypotension promptly w/ blood and fluid replacement
• Monitor central venous & arterial pressure & hourly urine output
• Assess renal function continually
• Make sure you are transfusing the right blood type during blood transfusions
• Prevent and treat infections (UTI’s) promptly.

Question 7

What are some cardiovascular system manifestations of ARF?

Answer 7

• Heart failure - Due to the fluid overload (during the oliguric phase) and hypertension (From the RAAS system being activated from poor renal perfusion)
• Pulmonary edema - ↑ pulmonary capillary permeability, Fluid overload, left ventricular dysfunction
• Dysrhythmias - Electrolyte imbalances (especially hyperkalemia and hypocalcemia)
• Peripheral edema - Fluid overload and right ventricular dysfunction
• Hypertension - Fluid overload, ↑ sodium retention

Question 8

What are some hematological system manifestations of ARF?

Answer 8

• Anemia - due to ↓ erythropoietin secretion, Loss of RBCs through GI tract, mucous membranes, or dialysis, ↓ RBC survival time, Uremic toxins’ interference with folic acid secretion
• Alterations in coagulation - Due to platelet dysfunction
• ↑ Susceptibility to infection - Due to ↓ neutrophil phagocytosis

Question 9

What are some electrolyte imbalance manifestations associated with ARF?

Answer 9

Metabolic acidosis due to:

• ↓ Hydrogen ion excretion
• ↓ HCO3 reabsorption and generation
• ↓ Excretion of PO4 salts or titratable acids
• ↓ Ammonia synthesis and ammonium excretion

Question 10

What are some respiratory system manifestations of ARF?

Answer 10

• Pneumonia - due to thick tenacious sputum from ↓ oral intake, depressed cough reflex, ↓ pulmonary macrophage activity
• Pulmonary edema - Fluid overload, left ventricular dysfunction, ↑ pulmonary capillary permeability

Question 11

What are some gastrointestinal system manifestations associated with ARF?

Answer 11

• Anorexia, nausea, vomiting - due to Uremic toxins, decomposition of urea releasing ammonia that irritates mucosa
• Stomatitis and uremic halitosis - due to Uremic toxins, decomposition of urea releasing ammonia that irritates mucosa
• **Gastritis and bleeding - **due to Uremic toxins, decomposition of urea releasing ammonia that irritates mucosa, causing ulcerations and increased capillary fragility

Question 12

What are some neuromuscular system manifestations associated with ARF?

Answer 12

Drowsiness, confusion, irritability, and coma - Due to uremic toxins producing encephalopathy, metabolic acidosis, and electrolyte imbalances (K+)

**Tremors, twitching, and convulsions - **Due to uremic toxins producing encephalopathy, ↓ nerve conduction from uremic toxins

Question 13

How would you manage a patient with ARF?

Answer 13

• Monitor labs (peaks & troughs for drugs)
• Monitor fluid & electrolyte balance, I&O’s
  
  • DAILY WEIGHTS
  • L/o for fluid excesses, listen to lung sounds, look for JCD, examine presacral and pretibial areas several times a day for generalized edema
  • Look for possible hidden sources of potassium in food/meds
• ** Reduce metabolic rate - bed rest during stages of disease**
• Prevent infection and prevent renal injury
• Skin care - skin is dry and susceptible to breakdown w/ edema
• Monitor dietary intake of protein, phosphorus, NaCl, and k+

Question 14

What is the DOC for treating hyperkalemia in ARF patients?

Answer 14

Sodium Polystyrene sulfonate (Kayexalate)
Given (PO or retention enema)

NOTE: Monitor for bowel sounds for paralytic ileus before giving this medication