Renal System 5% Flashcards
Myoglobin
- Muscle protein / heavy pigment
- Seen in urine after extensive muscle injury (electrical burns, status epilepticus, crush injuries)
- May cause acute tubular necrosis by having direct toxic effect on tubule epithelial cells or inducing intratubular cast formation
- Prevent damange to tubules by forcing diuresis with fluids and osmotic diuretics
Recombinant Human Erythropoietin
Treats anemia resulting from reduced renal production of erythropoietin.
Erythropoietin
Hormone that promotes the production of red blood cells.
What causes anemia in a patient with chronic renal failure?
Decreased renal production of erythropoietin.
What Does Acute Pancreatitis Cause
Hypocalcemia -> Muscle Spasm -> Prolonged QT interval -> torsades de pointes
Hypocalcemia Causes …
- Muscle Spasms
- Stridor
- Paresthesias
Hypomagnesemia Causes …
Respiratory Arrest
Hypokalemia Causes …
- Asystole
- Premature Ventricular Contractions
- Paralytic Ileus
Hyponatremia Causes …
Seizures
Cardiac Output (CO) = ?
- Stroke Volume (SV) x Heart Rate (HR)
- (4 to 8 L/min)
- Predicts oxygen delivery to cells
Cardiac Index (CI) = ?
- Cardiac Output (CO) / Body Surface Area (BSA)
- (2.5 to 4 L/min/m2)
- Assessment of cardiac output value based on patient’s size
Kidneys receive what percentage of Cardiac Output?
- 20% to 25% (approx 1200 ml/min)
- Without sufficient CO, kidneys cannot perfuse properly and filtration cannot be effective
Rhabdomyolysis
- Acute muscle destruction
- Associated with myoglobinuria
- Common cause for acute tubular necrosis (ATN) in normotensive patients with crush injuries
Increase in urine specific gravity is indicative of …
Dehydration
Prerenal Acute Kidney Injury
- “Before”
- Result of inadequate perfusion of a normal kidney > decreased glomerular filtration rate
- Significant cause: dehydration
- BUN/creatinine ration greater than 10:1 -Hemorrhage
Hyperkalemia Causes …
- Gastric motility (Diarrhea)
- Flaccid paralysis (Partially depolarizing the muscle cell membrane, preventing further depolarization)
Hypermagnesemia Causes …
- Diminished deep tendon reflexes Muscle weakness
- Smooth muscle relaxation
- Hypotension
- Respiratory Muscle Paralysis Respiratory arrest
Calculating Fluid Volumes for Acute Kidney Injury (ARF) patients on Fluid Restrictions
Replace what was previously lost and add an allotment for insensible losses that cannot be tracked (approx 500ml)
What is indicated when Blood Urea Nitrogen (BUN) is greater than 100 mg/dl for a patient in acute tubular necrosis (ATN)?
DIalysis
Loop Diuretics
- Most potent diuretic
- Block the reabsorption of sodium chloride at the thick segment of the medullary ascending loop of Henle.
- Results in large diuresis of isotonic urine
Loop Diuretic Meds
Furosemide (Lasix)
Osmotic Diuretic Meds
Mannitol
Aldosterone Antagonists Diuretic Meds
Spironolactone (Aldactone)
Dialysis Disequilibrium Syndrome
- Occurs when urea is removed from the blood at a rate faster than it is removed from the brain tissue.
- Greater amount of urea in the brain causes a fluid shift resulting in cerebral edema
- During dialysis/hemodialysis treatments
- Headache, nausea, agitation, confusion, twitching
- Prevent by slowing blood flow rate which slows the rate at which solute is removed from the vascular space
Hyposmolar Hyponatremia
- Hyponatremia -> Psychogenic Polydipsia
- Neurologic manifestations are hallmark of hyponatremia
- Swelling of brain cells results from the intracellular movement of water
- Lethargy, confusion, and even coma
Acute Kidney Injury Risk Factors
- Any cause of hypoperfusion
- Cardiogenic shock
- Duration of cardiopulmonary bypass
- Antibiotic therapy
Angiotensin-Converting Enzyme (ACE) Inhibitors
- Block the conversion of angiotensin I to angiotensin II.
- Angiotensin II causes vasoconstriction and blocks aldosterone.
- Aldosterone causes the retention of sodium and water and the excretion of potassium.
- ACE Inhibitors cause the excretion of sodium and water and the retention of potassium
Hypovolemia Concerns
- Sympathetic Nervous System stimulation
- Narrowed pulse pressure
- Tachycardia
- Volume Depletion
- Temperature elevation
- Dry, sticky mucous membranes
- Small volumes of dark, concentrated urine
Reciprocal Condition to Hypocalcemia
Hyperphosphatemia
Hyperphosphatemia
- Impaired sensitivity of the skeleton to the bone-resorbing action of parathyroid hormone
- Reduced absorption of calcium
- Calcium trapped in insoluble form as calcium phosphate complexes
- Common problem in chronic kidney disease
Why is Albumin prescribed for patients with alcoholic cirrhosis that has peripheral edema and ascites?
- To reduce third-spacing
- Decrease in serum albumin (Primary intravascular protein) results in third-spacing
- Replacing albumin increases intravascular colloidal oncotic pressure to hold and pull fluid into vascular space
Antagonist for Hypermagnesemia
Calcium
Metabolic Acidosis is a result of the kidneys inability to do what?
Excrete the acid by-products of cellular metabolism
Metabolic Alkalosis is a result of the kidneys inability to do what?
Inability to excrete bicarbonate ions
Damage to the glomerulus causes what?
- Loss of protein and proteinuria
- Ex: glomerulonephritis, Goodpasture syndrome, and nephrotic syndrome
Electrolyte Imbalances in Acute Renal Injury and Chronic Kidney Disease
- Hypermagnesemia
- Hypocalcemia
- Hyperkalemia
- Hyperphosphatemia
Intrarenal or Intrinsic Acute Kidney Injury
- Problems “within”, changes to, and injury of the nephron -Intrarenal failure due to injury within the kidney
- Intrarenal-cortical: caused by an infectious or inflammatory process within the kidney
- Intrarenal-medullary: caused by prolonged ischemic injury or a nephrotoxin
Postrenal Acute Kidney Injury
- Problems “after” and relates to obstructive processes
- Renal failure caused by problem after the kidney
- Tumor, stone
- Involving the bladder
Potassium Movement with pH Changes
- Acidosis: Potassium leaves the cell and increases serum potassium levels
- Alkalosis: Potassium enters the cell and decreases serum potassium
- 0.1 pH change = 0.5 mEq/L potassium change
Cause of Acute Tubular Necrosis (ATN)
Nephrotoxic drugs
Indications of Dehydration in Elderly Patients
- Tachycardia
- Hypotension
- Oliguria
- Dry Mucous Membranes
- Poor Skin Turgor
Anion Gap Equation
- Anion gap = (Na + K) - (Cl + HCO3)
- (Normal < 15 mEq/L)
Immediate management for a patient requiring elimination of excess fluid in a patient with chronic kidney disease includes …
Dialysis
Best parameter to evaluate effectiveness of fluid removal during hemodialysis
- Postdialysis weight
- 1 pound = 500ml
Myoglobinuria occurs in what cases?
- Electrical burns
- Status epilepticus
- Muscle ischemia
- Statins
- Crush injuries (leading to muscle destruction and rhabdomyolysis)
Urine Creatinine Clearance
Comparison between the creatinine in the blood and the creatinine excreted in the urine
Glomerular Filtration Rate (GFR)
- Evaluationes the ability of kidneys to filter a waste product (creatinine) that is neither reabsorbed nor secreted.
- Passive filtration of blood through the glomeruli
Refeeding Syndrome
- Nutritional support allows cells to begin making more adenosine triphosphate (ATP)
- Phosphate supplies are depleted
What should not be restricted during the oliguric phase of acute kidney injury?
- Carbohydrates
- Inadequate carbohydrate intake can cause catabolism
Peritoneal Dialysate Color Change
- Clear/Pale Yellow
- Amber
- Brownish
- Red/Pink
- Cloudy
- Clear/Pale Yellow: Normal
- Amber: Bladder Perforation
- Brownish: Bowel Perforation
- Red/Pink: Bleeding in the peritoneal cavity
- Cloudy: Infection in the peritoneal cavity
Acute Renal Failure Prevention
- Comorbidities
- Diabetes
- Heart failure
- Hypternsion
- Avoid potentially nephrotoxic substances
- Antibiotics
- NSAIDs
- Ace inhibitors, ARBs
- Antineoplastics
- Contrast media
- Diuretics
- Careful assessment and monitoring
- Fluid balance
- Hemodynamics, hypotension
- Renal function, labs
- Urine output
Blood Urea Nitrogen (BUN)
- Measures the amount of nitrogen in the blood that comes from the waste product urea (formed in liver)
- Dehydration and shock may elevate BUN, not best parameter for monitoring renal function or glomerular filtration rate (GFR)
- Normal 10-23 mg/dL
Creatinine
- Non-protein waste product of creatinine phosphate metabolism by skeletal muscle tissue
- Better indicator of renal function (GFR) than BUN
- Normal: males 0.8 - 1.4 mg/dL; females 0.6 - 1.1 mg/dL
24-hour Urine for Creatinine Clearance
- Best indicator of glomerular filtration rate (GFR)
- Variables needed to calculate include urine creatinine, serum creatinine, and volume of urine
Glomerular Filtration Rate (GFR)
- Volume of plasma filtered from the glomerular capillaries into Bowman’s capsule per minute
- Normal GFR = 125 mL/minute, total blood volume filtered - 60 times per day
- Normal urine volume is ~1000 mL/day
- GFR inversely related to the serum creatinine (NOT the BUN)
RIFLE Criteria for Renal Failure
