Week 4: Kidney injury, renal failure Flashcards Preview

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Flashcards in Week 4: Kidney injury, renal failure Deck (55):

Role of Kidneys 

  • Production and excretion of urine.
  • Excretion of urea (this is a by product of protein metabolism).
  • The kidneys maintain the pH balance (acid and base) throughout the body.
  • Regulation of the amount of water that is retained and excreted by the body.
  • Assistance with fluid and electrolyte balance throughout the body.
  • Production of Erythropoietin hormone (which has a role in the production of red blood cells).
  • Compensatory functions (such as assistance with increased/decreased blood pressure).


Na+, K+, Cl-, Ca2+, Phosphorus, Magnesium Norms?

Normal Range

Sodium (Na+)            135-145 mEq/L
Potassium (K+)           3.5-5 mEq/L
Chloride (Cl-)              100-110 mEq/L
Calcium (Ca2+)          8.5-10.0 (total) mg/dL
Phosphorus (Po4-)    2.5-4.5 mg/dL
Magnesium (Mg2+)   1.8-2.5 mEq/L


proximal convoluted tubule

reabsorption of sodium potassium calcium and glucose, uses active transport


thick descending

absorption of na through active transport but get water as well


thick ascending

sodium chloride and bicarb being reabsorbed


distal tubule



collective tubule

selectively allow water reabsorption based on adh, it's the last ditch effort to maintain ph.  Bicarb and hydrogen and K+ reabsorbed


Antidiuretic Hormone

  • Increases the permeability of collecting tubule cells to water.
  • Increases water, but not electrolyte reabsorption



  • Converts angiotensin into angiotensin I which is then converted to angiotensin II
  • Angiotensin II causes vasoconstriction and the release of aldosterone (important for na+ reabsorption in the distal tubules)



  • Promotes sodium reabsorption in the distal tubules
  • Leads to increase water absorption


  • Urinalysis
  • Volume
  • pH
  • Protein
  • Glucose/ketones
  • Sediment
  • Osmolality
  • Sodium concentration
  • Fractional Excretion of Sodium Test


What do each of these tests help identify

  • Urinalysis
  • Volume: less than 30, they are anuric
  • pH: between 5 & 6.5.  High = UTI.  Low= acidodic states in the body
  • Protein: never normal in urine.  Check it with 24 hour urine collection
  • Glucose/ketones: present when high glucose serum.  Spillage above 200.  Ketones present for fat metabolism
  • Sediment: some time of cellular breakdown.  Not normal.  Good indicator for pre-renal failure
  • Osmolality: 300-900.  Specific gravity 1.001-1.022.  If specific gravity high= sediment and renal damage.
  • Sodium concentration: less than 10 is normal.  If elevated, think of renal failure.
  • *Fractional Excretion of Sodium Test*: compares serum sodium to urine sodium.  Greater than 1%= intrarenal failure.  1% or less= pre-renal failure




Blood Studies for renal failure

Creatinine/ Creatinine Clearance
Estimated Creatinine Clearance formula
(140-age) X weight in kg/ (Plasma Creatinine mg/dL) X 72

Blood Urea Nitrogen: increases in renal failure, GI bleed, dehydration, trauma.   
8-20 mg/dL (normal)

BUN/Creatinine ratio:   
Based on serum creatinine
BUN:Creatinine – 10:1 (normal)

-when ratio goes down: liver failure, fluid volume overload, 

-ratio up: dehydration, catabolic states or high protein diets

Osmolality: Up= kidneys not filtering properly
Normally 280-290

Uric Acid: elevated=kidneys not filtering uric acid properly
2-8.5 mg/dL

Hemoglobin & Hematocrit:  decrease shows renal problems
Men 13.5-17.5 g/dL & 40-52%
Women 12-16 g/dL & 37-48%






Increased Anion Gap

Increased anions: much more common than decreased
Metabolic acidosis
Lactic acidosis
Uremic acidosis

Ingestion of chemicals
Ethylene glycol


Decreased cations


Anion Gap

Provides insight into the chemical neutrality of the blood
Na+  + (Cl- + HCO3-)
Normal is 12 mEq/L



Decreased Anion gap

Decreased Anion Gap

  • Increased cations: Hypercalcemia, Hyperkalemia, Hypermagnesemia
  • Lithium
  • Myeloma
  • Decreased anions: hypoalbuminemia


Risk Factors for Excessive Fluid Loss

  • Fever
  • Environmental
  • Hyperventilation
  • Gastrointestinal loss
  • Third Spacing
  • Burns
  • Renal Loss
  • Surgical Blood Loss


1 liter of fluid =?kgs

1 liter of fluid = 1kg


Oliguria in a child 

an output of less than 0.5 mL/Kg/hour


Acute Kidney Injury

  • Classified as: Sudden loss of renal function resulting in impairment in fluid/ electrolyte and/or acid-base balance.
  • 5% of all hospitalized patients develop AKI
  • 20% of ICU patients develop AKIMortality associated with ARF remains 40-70%
  • Of those who survive, 45% will have return of renal function




Types of kidney failure

  • Pre-Renal: occurs before you get to the kidneys.  Hypovolemia, blockages.  Can lead to Intra-Renal.
  • Intra-Renal: Occurs inside the kidney.  Metabolites collecting and causing damage, trauma, toxicity, etc.
  • Post-Renal: Involves ureters, prostate, and bladder.  


Risk Factors for AKI/ ARF

  • Diabetes (Type I or II)
  • Chronic renal insufficiency
  • Heart disease (heart failure)
  • Hypertension
  • Advanced age
  • Sepsis


Contributing Factors in the Development of AKI/ARF Pre-renal

  • Hypotention
  • Hypovolemia
  • Decrease CO
  • Dehydration
  • Vascular Disease
  • Renal Vein Thrombosis
  • DM




Contributing Factors in the Development of AKI/ARF Intrarenal

  • Nephrotoxic episodes
  • Infection
  • Systemic inflammation
  • Injured red blood cells
  • Hemolytic blood transfusion reactions
  • Glomerular diseases (systemic lupus, glomerulonephritits)
  • Rhabdomylolysis




Contributing Factors in the Development of AKI/ARF postrenal

  • Medication that interferes with normal bladder emptying.
  • Benign prostatic hypertrophy (BPH)
  • Prostate cancer
  • Ovarian cancer
  • Obstruction of a urinary catheter
  • Renal calculi
  • Bladder/pelvic neoplasms
  • Urethral strictures


Pharmacological Causes and Agravators of AKI/ ARF

Contrast media
Diuretics (Furosemide)
Heavy metals (mercury, gold lead)
Organic chemicals or solvents
Nephrotoxic antibiotics (Gentamycin/Piperacillin)
ACE Inhibitors

Any medication containing magnesium tetracycline
Nonsteriodal anti-inflammatory agents


Clinical Manifestations of AKI/ ARF

  • Decreased urine output (urine may be pink or reddish in color)
  • Edema (face, arms, legs, feet eyes)
  • Flank pain/Pelvic pain
  • Poor appetite (nausea, vomiting)
  • Bitter or metallic taste in mouth
  • Dry itchy skin
  • Easy bruising
  • Fatigue
  • Seizures/LOC
  • Shortness of breath
  • Arrhythmias
  • Sudden weight gain


The Four Phases of AKI/ARF

Onset Phase: from hours to a day
-Renal flow at 25% of normal
-Oxygenation to the tissue at 25% of normal
-Urine output at 30 ml (or less) per hour
-Urine sodium excretion greater than 40 mEq/L.


Oliguric Phase: lasts 8-14 days.  Tubular wall damage
-Significant decrease in GFR
-Increase BUN/Creatinine
-Electrolyte Imbalance
-Metabolic Acidosis


Diuretic Phase: Occurs if problem corrected. Lasts 7-14 days.
-Increase in GFR
-Urine output as high as 2-4 L/day
-Renal cells that cannot concentrate urine

Recovery Phase: lasts months to a year.  Cells start having some recovery and generation
-GFR returns to70-80% Baseline
-Renal Tubules begin to function
-Fluid/ electrolyte balance returns




Diagnostic Imaging Studies in AKI/ARF

  • Creatinine Clearance Test: 
  • Ultrasound: look to see if there's a mass or obstruction 
  • Doppler Studies: look at vascular and arterial flow
  • Nuclear Studies: looking for a tumor or mass
  • Renal Biopsy: looking for cancer causing or some sort of systemic autoimmune disorder


Laboratory Findings for Prerenal vs. Intrarenal Failure

urine osmolality

urine sodium



See table


Medical Management of AKI/ARF

  • Address underlying cause
  • Maintain intravascular volume: monitoring how much output and dialyzing them or giving diuretics to get the volume out
  • Maintain MAP: want it above 70.  For elderly person, 90-100.
  • Discontinue nephrotoxic agents
  • Correct Acidosis
  • Correct hemolytic issues
  • Correct electrolyte imbalances
  • Strict I & O’s and daily weights
  • Fluid and diet restrictions


a loop diuretic that can be used to increase urinary flow with the intent of flushing out cellular debris that may be causing an obstruction.

Furosemide (Lasix)


an osmotic diuretic that can be used to dilate renal arteries by increasing the synthesis of prostaglandins (resulting in restored renal flow).



at low doses (1-5 mcg/kg/min), dopamine dilates renal arterioles and increases renal blood flow and glomerular filtration. Because dopamine (even at low doses) can cause tachycardia, myocardial ischemia and arrhythmias it use should be considered carefully.



this medication can help reverse acute renal failure when the cause is thought to be from a nephrotoxic source.

N-acetylcysteine (Mucomyst)


Extracorporeal Therapies in AKI/ARF


Peritoneal dialysis: Not used in ARF
Hemodialysis.  Good for quick removal of water and toxins



Less likely to cause hypotension: Hemodynamic stability
Correction of metabolic acidosis.  Quicker kidney recovery time.  Correction of malnutrition.  Solute removal


Three types of dialysis access

Venous Catheters: used for dialysis.  Heparinized.  Cannot use for blood draw. Used with short and long term dialysis.

Arteriovenous catheters (fistula): From artery and the vein.  more for long term dialysis. (wait 1-3 months

Synthestic Grafts: Similar, but connects from a synthetic graft that connects aretery and vein.  Has more complications than AV fistula (wait 2-4 weeks)


Nursing Care of the AV Fistula

  • Cleanse with Soap and water daily
  • Limit contact with site
  • Assess for signs of infection
  • No BP or needle sticks to arm
  • Assess site for Thrill/bruit
  • Patient teaching to avoid pressure to site




Risk for increased clotting during dialysis.  What is the reversal agent?



HIT acronym

heparin induced thrombocytopenia



high concentration to low concentration.  Not great for person in renal failure, but good for fluid volume overload



from high concentration to low concentration.  Plasma is low, dialysate is high



based on hydrostatic pressure.  Positive in the blood, negative in the dialysate, allows both water, small, and moderate sized molecules to transfer over.  


Types of Continuous Renal Replacement

  • Slow Continuous Ultrafiltration (SCUF): 100-300 ml taken off every hour.  Good for removing fluid, but not good for uremia.
  • Continuous Venovenous Hemofiltration (CVVH): 7-30 liters removed every 24 hours.  Can be used for convection.
  • Continuous Venovenous Hemodialysis (CVVHD): Used a lot.  Good at getting fluid off, but not the moderate sized molecules
  • Continuous Venovenous Hemodiafiltration (CVVHDF): Good for small and moderate sized molecules.  Run continuously, low rate, over 24 hours.  Best type for acute renal failure pt.


Assessment and management pre, during, and post proceedure dialysis pt.

Assessment & Management:

Pre-procedure: Vital Signs, Dry Weight, Electrolytes
Procedure: Dialyzers, Dialysate, Hemodynamic stability
Post Procedure: Fluid  volume, Dysrhythmias, Muscle cramps, Dialysis Disequilibrium


Advantages and disadvantages for intermittent therapy vs. continuous therapy

see table


t waves peaked

 k+ 5-6.5


prolonged PR interval 

6-6.5 k+


wide qrs no p wave



Overview of Hyperkalemia Treatment  table insulin, calcium gluconate/carbonate, salbutamol, ion exchange resin, haemodialysis

see table


Most common colloids given

  • albumin 5%: giving volume
  • Albumin 25%: more hypertonic, fluid shift from extravascular to intravascular
  • Has high molecular weight, so it doesn't cross dialysate membrane well.  Helps keep fluid inside pt. easier


Severe Metabolic Acidosis common in AKI ph?

pH less than7.2


treatment of acidosis common in AKI

Alkaline Medications
Sodium bicarbonate tablets)

Sodium bicarbonate???
Used in severe acidosis.  Many complications. Now try to not give this bc increases sodium levels and osmolarity.






Things that can occur that cause acute renal failure that are outside the norm

  1. Rapidly progressive glomerulonephritis: seen with autoimmune disorders.  Confirm diagnosis with renal biopsy.
  2. Haemolytic‐uraemic syndrome: Pt has ecolli.  Do plasma exchange to get ecoli out of the system
  3. Tubulointerstitial nephritis: Drug induced by steroids.  Removal of steroids and then therapeutic support
  4. Contrast nephropathy: Contrast dye being given.  Nac given day before and day of to help ward it off
  5. Rhabdomyolysis: Muscle breakdown, endotoxin cascade, leads to renal vasoconstriction and ischemia. Decreased vascular volume to kidneys Leads to acute tubular necrosis.  Push fluids to get out myoglobin toxins and promote 200ml an hour urine output
  6. Liver disease—hepatorenal syndrome: Less than 10% of people will live from this.  Standard treatment is liver transplant.  Kidneys have shut down.  


Nursing Diagnosis for ARF

  • Alteration in urinary elimination
  • Fluid volume deficit
  • Fluid volume overload
  • Altered nutrition (less than bodily requirement)
  • Potential for impaired skin integrity
  • Decreased cardiac output
  • Activity intolerance 


How to prevent ARF?

  • Recognize that patients with pre‐existing renal impairment are at higher risk of developing further renal insufficiency—treat and monitor accordingly
  • Temporarily withhold nephrotoxic (especially ACE‐I, ARBs, NSAIDs) and diuretics (to prevent dehydration) when patients become unwell—either in the community or in hospital
  • Ensure that patients remain adequately hydrated, to maintain renal perfusion
  • Remember to monitor renal function after starting, or increasing the dose, of ACE‐I or ARBs (check one to two weeks later)
  • Where necessary, adjust drug doses in patients with renal impairment
  • Monitor drug levels when using aminoglycoside (gentamicin) and/or glycopeptide (vancomycin) antibiotics—and adjust dose accordingly
  • Hydrate the patient and consider using N‐acetyl cysteine before procedures entailing radiological contrast media