Module 12 - Dialysis Flashcards
Hemodialysis
process of separating elements in a solution by DIFFUSION across a semi permeable membrane DOWN a concentration gradient
Hemodialysis does the job of …
the kidneys
Hemodialysis allows for what 2 processes?
- Process for removing end products of nitrogen metabolism (urea, creatinine, uric acid)
- Process for repletion of bicarbonate deficit associated with metabolic acidosis in CRF
What moves things around in hemodialysis
pressure moving down a concentration gradient via diffusion
How much blood is circulated through the dialyzer
100-250 mL in the dialyzer at one time moving through a semipermeable membrane
___ and ___ never mix in hemodialysis
blood and dialysate
*they are separated by a semi permeable membrane
How long does a hemodialysis treatment take
3 to 6 hours with an average of 4 hours
All the movement of hemodialysis is done by what kind of pressure
positive hydrostatic pressure
Hemodialysis can remove what from blood ata rate of 1 L/hr with a flow rate of 200-300 mL/hr?
Sodium and Water - goes across the membrane
Why is heparin administered into hemodialysis
when removing blood there is a greater chance of clotting so heparin is put into the extra corporeal blood as it is removed
The amount is determined by clotting times like PT and PTT
What sort of intravenous access is available for Hemodialysis
- Subclavian Catheter
- internal Jugular Catheter
- Aterio-Venous Fistula
- Arterio-Venous Graft
what IV accesses are more temporary for hemodialysis
- subclavian catheter
2. internal jugular catheter
What do we need to do to check for the arterio-venous fistula or aterio-venous graft access?
palpate to feel a thrill and auscultate to hear a whooshing bruit indicating pressure going from high to low (that means the fistula is working)
__ is much better than using a vein for IV access
fistula
What is the basic way hemodialysis works?
Blood removed –> waste products removed, electrolytes balanced, excess water removed, blood filtered –> Returned to body as cleaned balanced blood
How many times a week does hemodialysis occur
2-4 times a week
done in an open room with other patients
Why does dialysate not have to be sterile
because bacteria is too large to cross the semipermeable membrane
but machines are cleaned after use
Dialysate
fluid with concentrations of products like IV fluids would have but does not have to be sterile
has a lower pressure than the blood to allow movement
How does Na, K, and Cl levels compare between the blood and dialysate
Blood and Dialysate have about the same Na and Cl but there is less K in the dialysate to allow pulling of it out of blood
Why is Na about the same in dialysate and blood
because we pull off fluid rather than sodium
How does Bicarbonate and Acetate concentrations compare between blood and dialysate
Bicarbonate and Acetate is higher in dialysate since the person does not have enough in the blood - it will move into the blood then to correct metabolic acidosis
Why is acetate moved to blood in hemodialysis
it metabolized into bicarbonate and can fix metabolic acidosis once shifted
How do Mg and Ca concentrations compare between dialysate and blood
they are about the same concentration but can be altered depending on the person
this is why its important to draw water blood levels to check to see if changes are needed
how much creatinine and urea is in the initial dialysate
none so that way it can be pulled off and removed
What is a physiological issue with hemodialysis
there is a fair amount of loss of cells in the process which contributes to anemia
also the lysis of cells means there more K potentially getting back in
What could mitigate the effect of lysis of cells releasing K in hemodialysis
use of a large bore needle with filters to prevent cell breaking and large specific tubing to prevent cell breakage
Why is there dextrose in the dialysate
to maintain oncotic pressure but it will not cross the membrane
What is movement of particles across a semi permeable membrane dependent on in diffusion
molecular weight and configuration of molecules
pore size of semi permeable membrane
solute concentration on both sides
Which way does Na, K, Cl, and HCO3 move in hemodialysis
in both directions to equalize concentrations
typically K goes into dialysate and bicarbonate moves to blood though
Which way does urea and creatinine move in hemodialysis
move from the blood into the dialysate solution from the concentration gradient
How does blood, cells, and plasma proteins move in hemodialysis
they stay on the blood side as the molecules are too large
Osmosis
movement water molecules from an area of higher concentration of osmotically active particles to a lower one
Which way does osmosis move in hemodialysis
pulls water from the blood into the dialysate solution
What helps osmosis occur for moving water to dialysate in hemodialysis
glucose/dextrose - osmotic pressure (pull)
Hydrostatic Pressure
fluid on the high pressure side of a semi permeable membrane moves to the lower pressure side
How does hydrostatic pressure work in hemodialysis
pressure (push) is applied to the blood which results in filtration of water from the blood into the dialysate
How does Temperature impact dialysis
as temperature increases, rate of diffusion and osmosis also increase
so the dialysate should be the same temperature as blood or slightly higher to speed things up, but not too high and too fast
Fresh Dialysate pumped through the machine is always…
coming in contact with blood that is constantly moving through the system
but they never mix
Why may more venipuncture occur with hemodialysis and what may it cause
lots of blood draws if health is unstable and they need custom dialysate (stable health can get regular dialysate and less venipuncture)
this contributes to pain and anemia
Potential Complications of Hemodialysis
Hypervolemia
Hypovolemia
Hemolysis
Dialysis Disequilibrium Syndrome
Transfusion Hazards
Physical Discomforts
Blood leaks, air embolisms, and clotting in the dialyzer
Why may hemodialysis cause hypervolemia
from accidental infusions of saline into the patient
why is hypervolemia particularly bad for hemodialysis patients
often they have a cardiac history so the hypervolemia is very bad as water follows salt for their heart
this can cause a cardiac event quickly
Why may hemodialysis cause hypovolemia
excessive ultrafiltration too rapidly or efficiently
removal of excess water and electrolytes too fast can mean the body cannot adapt quickly and hypovolemic shock occurs
Why may hemodialysis cause hemolysis
wrong dialysate concentration or high temperature
once they are lysed the person can become more hypovolemic
the wrong concentration can also increase K levels and contribute to anemia as well
Dialysis Disequilibrium Syndrome
may occur with the initiation of dialysis
High levels of urea and creatinine in the blood and CSF are not removed quickly causing an osmotic gradient which pulls water into the CSF
this results in cerebral edema, increased ICP, N/V, convulsion, and coma
What are some transfusion hazards available from hemodialsysi?
if they need transfusions they are at risk for:
Reactions
HIV
Hepatitis
Excess K+
Why may physical discomforts occur with hemodialysis
chest pain and muscle cramps from rapid dialysis
repeated venipuncture pain with large needles
What are some psychological dysfunctions from Hemodialysis
Body image issues like incorporating the machine into their body image
Grief from loss of kidney functions
Frustration from basic drives like hunger and thirst from restricted diet and decreased sex drive changing relationships
Fear of life and death, the future, QOL
Dependence on healthcare and inability to do other life actions
Denial
Powerlessness Despair Hopelessness
How does suicide attempt rate compare in ESRD patients
it is 400x more than normal
Peritoneal Dialysis
another dialysis option
this dialysis uses the many capillaries of the peritoneum and the peritoneum itself as a semipermeable membrane for dialysis
What is the number one risk of peritoneal dialysis
Peritonitis
What is a huge difference and consideration for peritoneal dialysis compared to hemodialysis
in peritoneal dialysis the dialysate must be sterile as the peritoneum is a sterile cavity and bacteria could get in and cause peritonitis
What are signs of peritonitis with peritoneal dialysis
cloudy drainage and rebound tenderness
How often does peritoneal dialysis occur
3-5 times in 24 hours while awake
Will more peritoneal dialysis drainage come out or go in
come out
Why is peritoneal dialysate warm
to dilate blood vessels and improve urea clearance
another benefit is that it contributes to client comfort
CAPD - Continuous Ambulatory Peritoneal Dialysis
a continuously running peritoneal dialysis bag
it gives more independence and ability to take vacations
it does require cognitive ability and manual dexterity to use though and has a higher risk of infection
Why may CAPD be a preferred choice to hemodialysis
lots of urea and fluid builds up between hemodialysis treatment and this has less shock in comparison and less buildup when removing
also some people have fragile cardiovascular systems and need peritoneal dialysis as it is easier on the system
How does peritoneal dialysate differ from hemodialysis dialysate
- Absolutely no K in the dialysate since we want it coming out
- Na, Cl, Ca, and Mg are about the same concentrations as blood
- In this glucose acts as an osmotic force to pull fluid from the blood and since there is no hydrostatic pressure it is more gentle on the body
Benefits of Peritoneal dialysis
less stressful than hemodialysis in hemodynamically unstable patients
allow patients to be more flexible in terms of schedule, travel, and employment
there are automatized machines available that work at night and can tell you if it is not working
Downfalls of Peritoneal Dialysis
it is less efficient that hemodialysis and longer treatment times are needed to get through a cycle
also you are continuously attached to the bag which can get old
you can feel dialysate in the peritoneum and can feel bloated at times
How long is a peritoneal dialysis cycle
8 hours
What in peritoneal dialysate causes osmotic removal of water
glucose
What can the exchange volume of fluid into the peritoneum in peritoneal dialysis be
1-3 Liters
1 liter isnt bad but you can feel distention and bloating with 3
Where is peritoneal dialysate infused
between the visceral and parietal components of the peritoneum - so the peritoneal cavity where there is abundant capillaries to do exchange
Peritoneal Dialysis is infused via a ___ catheter
Tenckhoff
____ are the membrane for exchange in peritoneal dialysis
capillaries
How does drainage work in peritoneal dialysis
it is periodically drained and replenished in a tidal fashion
some is put in but more is drained out (but not as much as hemodialysis
ex: CAPD does this 4 times a day
What is the goal of peritoneal dialysis
more drainage than inflow (negative water balance - removal of excess)
What is the major complication of peritoneal dialysis
Peritonitis
repeated episodes will scar the peritoneum and reduce dialysis surface making poor exchange occur
How to prevent peritonitis in peritoneal dialysis
Catheter tunneled under the skin exiting caudally with 2 Dacron cuffs to decrease infection risk
strict asepsis
UV radiation treatment to kill anything in the catheter
cap off procedure to prevent bacteria entering
Tenckhoff Catheter
a catheter with 2 Dacron cuffs so Sub Q tissue grows into the Dacron and prevents bacteria entry
the first cuff is very close to the skin
this catheter can be used for ascites drainage as well
Benefits of CAPD
need fewer blood transfusions
can eat a normal diet without fluid restriction since its always removing toxins
insulin can be added to dialysate for diabetics
do not spend long periods of times multiple times a week on a hemodialysis machine
also do not get wide variations in H and bicarb or K levels because this is continuous
Acute Renal failure (ARF)
syndrome characterized by relatively rapid decline in renal function (measured by GFR) over a period of hours to days
develops very fast
What is significant ARF associated with?
DAILY increases in serum creatinine and urea nitrogen
Why is creatinine increases so significant in ARF
kidney function has decreased as creatinine increased
so if creatinine jumps from .9 to 1.9 that’s a 50% kidney function loss, triple from .9 to 2.7 means a 75% loss of function
What is the most common cause of ARF
iatrogenic (we caused it)
50% of cases are iatrogenic with 60% being related to surgery
5% of patients total
What sort of urinary output is common in ARF
Oliguria with urine flow less than 400 mL a day
Anuria could also occur but is uncommon
What are the 3 types of ARF
Pre Renal (Before)
Intra Renal (in)
Post Renal (After)
Pre Renal ARF
cause before the level of the kidneys
often it is hypovolemia causing this but there are other reasons
Intra Renal ARF
cause is in the level of the kidneys itself like anything that kills nephrons
Post Renal ARF
cause is after the level of the kidney
so something like an obstruction after this level causing retention or backup
Pre Renal ARF Causes
Hypovolemia (The main one)
Cardiovascular Disorders
Peripheral Vasodilation
Renovascular Obstruction
Severe Vasoconstriction
How does Pre Renal causes lead to ARF
it decreases the effectiveness of perfusion of the kidney parenchyma (nephron)
What are some causes of Pre Renal ARF Hypovolemia
hemorrhage
burns
dehydration
GI losses like diarrhea and vomiting
diuretics and osmotic diuresis
third spacing like in peritonitis and burns
premature separation of the placenta
trauma
What are some causes of Pre Renal ARF Cardiovascular Disorders
arrhythmias
cardiac tamponade
cardiogenic shock
heart failure
MI
anything that causes decreased kidney flow
What may cause peripheral vasodilation that leads to Pre Renal ARF
antihypertensive drugs
sepsis
leads to lack of perfusion and circulating blood volume
What may cause Renovascular Obstruction that leads to Pre Renal ARF
arterial embolism
arterial or venous thrombosis
tumor
blocks flow to the kidney
What may cause Severe vasoconstriction leading to Pre Renal ARF
DIC
eclampsia
malignant HTN
vasculitis
prevents flow to the kidney
Vasculitis
inflammation of the vasculature (constricts)
Post Renal Causes for ARF
Ureteral Obstruction
Bladder Obstruction
Urethral Obstruction
Examples of Ureteral Obstruction Post Renal Causes of ARF
blood clots
calculi
edema or inflammation
necrotic renal papillae
surgery - accidental ligation
tumors
uric acid crystals
Examples of Bladder Obstruction Post Renal Causes of ARF
anticholinergic drugs
ANS dysfunction
infection
tumor
Examples of Urethral Obstruction Post Renal Causes of ARF
1 is BPH
prostatitis
tumors
urethral stricture
Hydroureter
enlargement of the ureter from backflow to the kidney
What is the number one type of post renal cause of ARF in males
Urethral Obstruction from BPH
Why does obstruction cause post renal ARF
because the back pressure can kill nephrons and lead to not enough blood getting to the kidneys
Intra Renal (Renal) Causes of ARF
Acute tubular necrosis
obstetric complications
pigment release
parenchymal disorders
anything that kills the kidney itself
What are some examples of acute tubular necrosis intra renal causes for ARF
ischemic damage to nephrons from poorly treated or unrecognized pre renal failure
nephrotoxins like analgesics, anesthetics, antibiotics, heavy metals, radiographic contrast media and organic solvents
What are some examples of OB complications leading to intra renal ARF
eclampsia
postpartum renal failure
septic abortion
uterine hemorrhage
What causes pigment release leading to intra renal ARF
crush injury
myopathy
sepsis
transfusion reaction
Other Parenchymal Disorders that can cause Intra Renal ARF
Acute glomerulonephritis Acute interstitial nephritis Acute pyelonephritis Bilateral renal vein thrombosis Malignant nephrosclerosis Papillary necrosis Peri-arteritis nodosa Renal or multiple myeloma Sickle cell disease Systemic lupus erythematous Vasculitis
sometimes something liek MI, CPR< or transfusion reaction can cause damage yet it does not involve the kidney directly itself
What are the main reasons for Pre Renal, Post Renal, and Intra Renal ARF?
Pre Renal - Lack of perfusion / Hypovolemia
Post Renal - Obstruction
Intra Renal - Direct Organ Damage
What are the stages of ARF
- Oliguric Phase
- Diuretic Phase
- Recovery Phase
What signals the Oliguric Phase of ARF
decreased urinary output 50-400 mL/day and increased BUN and creatinine daily
Complications of the Oliguric Phase of ARF
infection
HF from hypervolemia
PE
hyperkalemia
metabolic acidosis
GI bleeding (stress ulcers)
How to manage infection in the oliguric phase
prevention of infection via NO indwelling catheter and good mouth care and pulmonary hygiene
How should fluid management be done in the oliguric phase
daily weight should be taken with expected loss of .5 to 1 kg per day from catabolism
fluid replacement is then based on these weights
In the oliguric phase it is important to avoid what?
negative nitrogen balance
for that reason high biologic value protein should be given for maintenance and repair, protein restrictions, sufficient carbs to stop catabolism of proteins and possible TPN if needed
Nephramine
a special formula of TPN for ARF patients with fewer amino acids
What may vary in Oliguric phase
Hyperkalemia levels
What can be done to manage mild, moderate, and severe Hyperkalemia
Mild - Kayexalate PO or enema
Moderate - GIK insulin
Severe - Calcium gluconate, GIK, dialysis
How do we manage and prevent acidosis in the oliguric phase
protein restriction
give sodium bicarbonate PO
dialysis if needed
How do we prevent GI bleeds in the Oliguric phase
there is a chance of GI bleed from ulceration of the wall so we can prevent this with H2 inhibitors like Pepcid and axis
Why does anemia occur in the oliguric phase
there is decreased production and survival due to azotemia occurring
What neurologic manifestations can occur in the oliguric phase
convulsions and coma indicating need for dialysis since it is a s/s of encephalopathy
ay change in LOC of mental status indicates dialysis need
Diuretic Phase
stage 2 lasting 7-14 days
urinary output progressively increases with it double each day until 1-2 L is met in 4-5 days
How long does the oliguric phase last
for a few weeks - this is a risk for hypervolemia
What is important to monitor for in the diuretic phase
hypovolemia since UO is increasing
Recovery Phase
Stage 3 of ARF lasting 3-12 months
it is a convalescent phase where kidneys finish healing
can take up to a whole year to fix and may need dialysis during that time but not after
ARF Prognosis
good chance for recovery but it takes time
Nursing Responsibilities during the Oliguric Phase
Administer IV fluids for rehydration and watch for overhydration
Consistently evaluate mental status including anxiety and level of understanding
do accurate I&O
administer kayexalate (PO preferably)
100-150 gm CHO daily to reduce protein catabolism
administration of loop diuretics
restrict proteins to 10-20 gm with high biologic value
know and prevent conditions increasing protein catabolism
prepare for peritoneal or hemodialysis if indicated
What fluid replacement is needed usually during the oliguric phase
usually 500-600 ccs to cover insensible water losses + whatever the UO was in the last 24 hours + any other measurable losses
Hypervolemia in the oliguric phase can lead to PE which can show as what on assessmetn
crackles in the lungs
Always take daily weights…
using the same scale
Why do we give Kayexalate in the oliguric phase
it can lower serum potassium levels 1-2 mEq every 24 hours
Why do we give 100-150 grams of carbohydrates to someone in the oliguric phase
to prevent protein catabolism and nitrogenous waste buildup
What are some examples of food with proteins of high biologic value
milk
eggs
Rapid administration or repeated doses of Lasix (loop diuretic) can cause what
deafness
We administer loop diuretics to work on the loop of Henle. How can we tell if it is ARF or hypo perfusion to the kidney when giving this?
A fluid challenge
We give fluid and the diuretic
If it is ARF there will be little UO but if it is hypo perfusion there will be UO
What are some conditions that increase protein catabolism that a nurse should know and prevent
fever
steroid use
immobilization
infection
necrosis
Nursing Responsibilities during the Diuretic Phase
Watch for dehydration and salt depletion from UO doubling
Monitor daily electrolytes
Replace fluids (volume lost in 24 hours (UO) + 500-600 cc of insensible loss)
Daily weights on the same scale
protein intake increases as long as the BUN is low
What measure of BUN can indicate an increase in protein intake during the diuretic pahse
A BUN under 80 mg/dL
Nursing Responsibilities during the Recovery Phase
Follow up care
self care
teaching if on a special diet or medications / continued temporary dialysis use
