Renal Flashcards
How much cardiac output is directed towards the kidneys?
20-25% ‘
What is a healthy GFR?
100-120 ml/minute
What is the function of the kidneys?
Filter the blood of waste products and excrete urine
What is bowmans capsule permeable to?
Water
Ions
Glucose
Amino acids
What is bowmans capsule not permeable to?
Proteins
RBCs
Other large molecules
What is the descending loop of henle permeable to?
Only permeable to water
What is the ascending loop of henle permeable to?
Only permeable to ions
What are the indications for diuretics?
Heart failure
Pulmonary edema
Liver cirrhosis
Hypertension
Raised intracranial pressure
What is the mechanism of action for loop diuretics?
Inhibit ion reabsorption along the ascending loop of henle
What is the most common diuretic used for heart failure?
Loop diuretics
What are examples of loop diuretics?
Furosemide
Bumetanide
Todemide
What are adverse effects associated with loop diuretics?
Metabolic alkalosis
Hypokalemia
Hypochloremia
What is the mechanism of action for thiazides?
Inhibit ion transport along the distal tubule
When are thiazides typically used?
As a secondary or adjunct diuretic for congestive heart failure
What are examples of thiazides?
Hydrochlorothiazide
What are adverse effects associated with thiazides?
Hyponatremia
Describe the mechanism of action for potassium sparing diuretics
Inhibits ion reabsorption at the collecting duct
Limits the amount of potassium lost
What is a drawback of potassium sparing diuretics?
Not a powerful diuretic
What is typically administered with potassium sparing diuretics?
Loop diuretics
Helps limit the amount of potassium lost
What is an example of a potassium sparing diuretic?
Spironolactone
What are some adverse effects of potassium sparing diuretics?
Hyperkalemia
Metabolic acidosis
What is the mechanism of action for osmotic diuretics?
Inhibits sodium and water reabsorption in the proximal tubule and loop of henle
Pulls fluid out of intracellular compartment into extracellular compartment
What are the common uses for osmotic diuretics?
Cerebral edema
Drug toxicity overdose
What is an example of an osmotic diuretic?
Mannitol
What are adverse effects of osmotic diuretics?
Increase plasma volume leading to increased cardiac workload
What is being examined during a urinalysis?
Color
Clarity
Concentration
Content
Chemical analysis
When analyzing kidney function, what values are we looking for?
BUN
Creatinine
Which is more accurate for determining kidney function, creatinine or BUN?
BUN will increase earlier in renal disease, but creatinine is a more accurate assessment
What creates creatinine?
Creatinine is a by-product of creatine-phosphate in muscle which is produced at a constant rate
What is urea a product of?
Protein metabolism
Describe what baroreceptors are
Nerve endings that feel or sense our blood pressure
What effects does the sympathetic nervous system have on the cardiogenic system?
Increase HR
Increase stroke volume
Increase contractility
Increase BP by vasoconstriction
What effects does the parasympathetic nervous system have on the cardiogenic system?
Decrease HR
Decrease stoke volume
Decrease contractility
Decrease BP by vasodilation
What does the juxtaglomerular apparatus have that helps regulate blood pressure?
Houses specialized cells that participate in RAAS
Renin angiotensin aldosterone system
What is the renin angiotensin aldosterone system responsible for?
Critical regulator of blood volume, electrolyte balance, and system vascular resistance
What are the specialized cells located in the juxtaglomerular apparatus?
Juxtaglomerular cells
Macula densa cells
Mesangial cells
What do the macula densa cells do?
Chemoreceptor
Distal convoluted tubule
Senses changes in filtrate concentrations
What do the mesangial cells do?
Provide structural support to the nephron
What do juxtaglomerular cells do?
Baroreceptor
Smooth muscle around the arteriole
Senses changes in pressure in the afferent arteriole
What causes the release of renin?
Juxtaglomerular cells sense decrease in blood pressure in the afferent arteriole
Macula densa cells sense a low sodium contraction in the filtrate of the DCT
What are the organs involved in the renin angiotensin aldosterone system?
Kidneys
Liver
Lungs
Adrenal gland
Where is angiotensinogen stored? And it what state?
Liver
Inactivated
What activates angiotensinogen in the liver?
Renin
What does renin turn angiotensinogen turn into once activated by renin?
Becomes angiotensinogen 1
Where does angiotensin 1 become angiotensin 2?
It becomes angiotensin 2 in the lungs when it interacts with angiotensin converting enzyme
What does angiotensin 2 do?
Generalized vasoconstrictor
Constricts afferent arteriole
Stimulates adrenal gland to produce aldosterone
What are the targets of aldosterone?
Distal convoluted tubule
Hypothalamus
What effect does aldosterone have on the DCT?
Promotes more sodium reabsorption
What effect does aldosterone have on the hypothalamus?
Activates antidiuretic hormone
Tells kidneys to reabsorb more water
What is the sympathetic nervous systems response to low blood pressure?
Secretes adrenaline which is a potent vasoconstrictor including the afferent and efferent arterioles
What is autoregulation in regards to the kidneys?
Local mechanism withing the kidney that maintain a consistent GFR over a range of systemic MAP
How does the kidney achieve autoregulation?
Myogenic mechanism
Tubular glomerular mechanism
What is the myogenic mechanism?
Baroreceptor
What is the tubular glomerular mechanism?
A chemoreceptor
What are the 3 types of acute renal injury?
Prerenal
Intrinsic renal
Postrenal
Describe prerenal injury
Issues arising before the kidney
Decreased blood flow, volume depletion
Describe intrinsic renal injury
Caused by a process within the kidneys
Damage to the tissue associated with trauma, infection and/or toxicity
Describe postrenal injury
Issue arising after the kidney
Obstruction of urine outflow
How is acute kidney injury diagnosed?
Decreased GFR
Increased Creatinine
Increased BUN
Lack of urine output
What is the time course for acute kidney injury?
Usually reversible
2 weeks - 2 months
What are the 4 phases of acute kidney injury?
Initial
Oliguria
Diuresis
Recovery
Describe chronic kidney failure
Progressive process
Gradual onset (months to years)
Deterioration inevitable, leading to dialysis/transplant
Describe the epidemiology of chronic renal disease
Increases as rates of DM and HTN increase
Incidence increases with age
Significantly greater in african americans
What is the pathophysiology of chronic kidney disease?
Characterized by nephron deterioration
Rate is dependent on etiology
Progression usually occurs in 5 distinct stages
What is the normal GFR?
> 90 ml/min
What are complications associated with end stage renal disease?
Fluid retention
Uremia/azotemia
What is the GFR of stage 5 renal disease?
<15 ml/minute
What the result of the fluid retention caused by kidney failure?
Respiratory compromise
Hypertension
Encephalopathy
What is the result of uremia/azotemia caused by kidney failure?
Toxins building up in the blood
What is the purpose of dialysis?
Removal of wastes and fluids from the blood
What are the three options for dialysis?
Continuous renal replacement
Hemodialysis
Peritoneal dialysis
Where is hemodialysis performed?
ICU
Inpatient or outpatient areas
How often is hemodialysis performed?
4 hour treatment 3 times a week
What is needed to perform hemodialysis?
Catheter or fistula
Where is continuous renal replacement therapy performed?
ICU only
What does hemodialysis cause?
Large fluid shifts
What is required for continuous renal replacement therapy?
Specialized nurses
Central dialysis catheter
What are the benefits of continuous renal replacement therapy?
Improved tolerance
Less fluid shifts
Where is peritoneal dialysis performed?
At home on patient schedule
What are concerns associated with continuous renal replacement therapy?
Clotting
Describe how peritoneal dialysis is performed
Permanent catheter placed in abdomen
Peritoneal cavity is filled with hypertonic solution to eliminated solutes and extra water into drainage bag
Why is peritoneal dialysis feasible?
The peritoneum is highly vascularized allowing for fluid exchange
When is peritoneal dialysis generally performed?
Overnight
Generally takes 8-9 hours
What are the risks associated with peritoneal dialysis?
Infection
Patient compliance
What is contraction alkalosis?
Occurs when there is a large loss of extracellular fluid
Plasma HCO3 concentration rises due to lack of fluid
What can cause contraction alkalosis?
Loop diuretics
Sweat losses in CF
What are interventions for contraction alkalosis?
Diamox
Chloride
Fluids
