Renal replacement therapy (RRT) Flashcards
HD - frequency
- 3x/wk on alternate days
- 4 hrs each time
HD - types of substances
water, urea, Cr, uremic toxin, drug
HD - mechanism of transport
1) diffusion
- conc gradient
- factors affecting rate: solute conc, solute characteristic, dialyser composition, blood & diasylate flow rate
2) ultrafiltration
- move water across membrane due to hydrostatic/osmotic pressure
- primary mean for removing excess body water
3) convection
- drag solute across membrane w fluid transport
- factors affecting: hydrostatic pressure, pore size of dialyser
HD - component of dialysis
1) diayser
- large canister w small fibres (semi-permeable membrane)
- conventional: small pore (urea, Cr)
- high-efficiency: larger surface area (WAter, urea)
- high flux: large pore (high MW substance, drug)
2) diasylate
- adjusted to meet patient need
HD - process
- extrarenal vascular circuit
1) patient blood transferred in polyethylene tubing into dialyser through blood pump
2) anticoagulant introduced to prevent clotting
3) blood pass through dialyser on 1 side of semi permeable membrane, dialysate enter from opposite direction on other side
4) exchange of substances
5) cleansed blood return to patient through venous line
HD - types of access - general
- early referral cuz takes time to prepare (Create & mature to be functional)
HD - type of access - arteriovenous (AV) fistula
- preferred, permanent
- gradual increase in size over time & allow repeated needle insertion
- use more distal blood vessel in arm before moving upward
- advantage: longer survival, lowest complications
- disadvantage: >/= 2 month to dilate/thicken/mature, difficult in patient w small vein (old, DM, PVD)
HD - type of access - AV graft
- synthetic graft (polytetrafluroethylene) under skin, act as artificial vein for repeated needling, permanent
- used if vein too small for AV fistula
- advantage: quicker maturation time (2-3 wk)
- disadvantage: shorter survival, higher complciation rate
HD - type of access - venous catheter
- temporary access, not to be lef tin patient for long
- indication:
1) AKI (short term HD)
2) when AV not an option - disadvantage: short lifespan, prone to complication, low blood flow rate, proper cleaning & care required, no contact w water
HD - goals
- desired dry weight (normotensive & free of oedema/SOB)
HD - monitoring
1) urea reduction ratio (URR)
- goal: > 65%
- (predialysis urea - post)/predialysis urea X 100
2) Kt/V
- fraction of patient body water cleared of urea during dialysis
- K = dialyser clearance, t = time, V = distribution vol of urea
- goal: Kt/v around 1.4, min 1.2
HD - advantage
1) higher solute clearance
2) dialysis adequacy parameters better defined
3) low technique failure rate
4) closer patient monitoring
5) IV administration of some drugs
HD - disadvantage
1) multiple centre visit
2) complications
3) infections
4) Rapid decline in residual kidney function until anuria
HD - HD related complication - hypotension - causes
1) hypovolemia
2) excessive ultrafiltration (drop in urine vol)
3) anti HTN med
4) target dry weight too low
5) diastolic dysfunction
6) autonomic dysfunction
7) low Ca, Na in diasylate
8) high diasylate temperature
9) meal ingestion (Food = vasodilation), light snacks ok
HD - HD related complication - hypotension - management
1) lower position of head to maintain blood flow to head
2) Reduce rate/turn off ultrafiltration (other transport still possible)
3) administer fluids
4) increase diasylate Na conc
5) switch to bicarbonate-buffered diasylate (if diasylate contain lactate)
6) Accurately set up dry weight 7) lower diasylate temp
8) midodrine (alpha adrenergic agonist), CI w CVS hist
9) correct anaemia
10) Administer O2
11) avoid large meal before/during HD
HD - HD related complication - cramp - cause
1) muscle hypoperfusion
2) hypotension
3) electrolyte/acid-base imbalance
HD - HD related complication - cramps - management
1) correct/prevent vol contraction & excessive ultrafiltration
2) Vit E: 400 IU @ bedtime
3) other agent: skeletal muscle relaxant, benzodiazepine, pramipexole (restless leg syndrome)
HD - HD related complication - N/V
cause: hypotension, dialyser reaction
HD - HD related complication - headache
cause: disequilibrium syndrome, caffeine withdrawal (From HD)
HD - HD related complication - chest/back pain
unknown
HD - HD related complication - pruritus - cause
1) inadequate dialysis
2) dry skin
3) secondary hyperparathyroidism
4) electrolyte abnormalities
5) histamine release
6) mast cell production
HD - HD related complication - pruritus - management
moisturiser, antihistamine
HD - HD related complication - fever/chills
cause: endotoxin release, infection
HD - HD related complication - overall management
paracetamol, diphenhydramine, prochlorperazine
HD - catheter related thrombosis - general
- blood clot within/outside catheter
- intrinsic (inside lumen) vs extrinsic (outside)
- suspected when blood cannot be aspirated from catheter but saline flow normally
HD - catheter related thrombosis - management
1) non pharm
- forced saline flush
- mechanical thrombectomy
- catheter stripping/removal
- exchange catheter over guidewire
2) pharm: intraluminal thrombolytics to lyse thrombus
- Alteplase (r-TPA): small dose per catheter port and allowed to stay inside for awhile, attempt to aspirate after 30 mins, repeat if function not restored
- Urokinase: aspirate after 4 min, aspiration attempt every 5 min, secondary injection required
HD - catheter related infection (CRSBI) - S&S
fever, chill, rigor, elevated white count
HD - catheter related infection (CRSBI) - risk factors
- DM, immunosuppression, (+) his of catheter infection
- S. aureus nasal carriage
HD - catheter related infection (CRSBI) - process
- obtain peripheral blood culture & culture from catheter site before starting Abx
HD - catheter related infection (CRSBI) - complications
endocartitis, bacteremia, sepsis
HD - catheter related infection (CRSBI) - AV fistula infection
- rare
- treat as subacute bacterial endocarditis x 6 wk
- maybe need to remove fistula if septic emboli
HD - catheter related infection (CRSBI) - synthetic graft infection
- treat for 2-4 wks
- maybe resection of infected portion of graft
HD - catheter related infection (CRSBI) - venous catheter - exit site infection
- external part where catheter leaves
- w/wo drainage
- topical antibiotics (mupirocin ointment) or IV (gram +ve)
- proper local exit site care
- no catheter removal unless infection not responsive to therapy
HD - catheter related infection (CRSBI) - venous catheter - catheter related bacteremia
- infection: send culture for testing: start empirical therapy (Abx that worked) before susceptibility results release then streamline according to results (resistance etc)
- remove catheter only if symptomatic > 36h/clinically unstable
- if stable & asymptomatic: culture-specific antibiotic coverage min 3 wks
- X place new permanent access until blood cultures (after stop antibiotics) have been -ve for at least 48 hr
- empiric therapy usually cover both gram +Ve and -ve
1) Gram +Ve: MSSA (Cefazolin), MRSA (Vancomycin, when theres hist of MRSA, need TDM)
2) Gram -ve: Gentamicin/Ceftazidime IV after each dialysis
HD - complications - HTN - causes
- excess fluid & Na intake
- RAAS/sympathetic sys problems
- ESA use
HD - complication - HTN - BP goals
- pre-dialysis: < 140/99 mmHG
- postdialysis: < 130/80 mmHg
HD - complication - HTN - manage excess fluid accumulation btwn dialysis session
- dietician counselling
- fluid restriction (~800mL)
- Na restriction
- increase ultrafiltration
- longer dialysis
- increase dialysis freq
- drugs that reduce appetite
HD - complication - HTN - manage by restart ACEi/ARB or DHP CCB
- end stage CKD stop ACEi/ARB cuz hyperphosphatemia , can restart after HD
HD - complication - HTN - management by diuretics
- can use if patient still peeing
- end stage kidney atrophy, not as effective as before, urine output stop
- stop diuretics when anuric
HD - complication - HTN - other management
- anti-HTN @ night to reduce nocturnal BP surge & minimise intradialytic hypotension
- hold AM dose of anti-HTN drug
- switch to drug that is cleared by dialysis if BP very low or vice versa
- ARB not dialysable
PD - process
1) diasylate instilled into peritoneal cavity through trans-abdominal catheter (surgically inserted) and allowed to dwell (remain in peritoneal cavity for 4-6h)
2) diffusion & ultrafiltration take place during exchange to remove metabolic waste
3) dialysate drained
4) repeat cycle a few times a day
PD - types
1) chronic ambulatory PD (CAPD): a few times a day
2) automated PD (APD): done overnight w/wo daytime dwell
PD - indications
1) haemodynamically unstable patients
2) significant residual kidney function
3) ambulant and desire self-care
PD - requirement
1) no major abdominal surgery in the past
2) motivated to adhere to therapy + family support
3) storage space to store bags of dialysate
4) good manual dexterity to do PD exchange on their own
5) good personal hygiene
PD - diasylate solution component
. vary concentration of electrolyte (Na, Cl, Ca, Mg, Lactate) and dextrose
. Dextrose
- hyperosmolar dextrose solution induce ultratfiltration by crystalline osmosis
- disadvantages: incompatibility w peritoneal mesothelial cells/peritoneal leukocytes
. Icodextrin
- iso-osmolar
- produce prolonged ultrafiltration by “colloid osmosis”
- fewer metabolic effects
PD - monitoring
Kt/v = 1.7/wk
PD - advantages
- more haemodynamically stable
- suitable for elderly & young patient
- > clearance of larger solute
- preserve residual kidney function
- intra-peritoneal (IP) drug administration (Abx for peritonitis)
- less blood loss & Fe deficiency
- no systemic heparinisation (no blood flow outside of body): good for patient experiencing heparin-induced thrombocytopenia (low platelet count from heparin administration)
- SC dosing of ESA possible
PD - disadvantages
- greater protein & AA loss, glucose load, peritonitis
- risk of obesity w glucose absorption (dextrose)
- complications
- inadequate ultrafiltration (& solute removal in certain patient
- patient burnout & high technique failure rate
- extensive abdominal surgery preclude PD
- no convenient access for IV meds
PD - complications - mechanical
kinking of catheter: inflow/outflow obstruction
PD - complication - infectious - peritonitis - definition
- elevated diasylate WBC > 100/mm^3
- > 50% PMN neutrophil
PD - complication - infectious - peritonitis - clinical presentation
- abdominal pain, cloudy effluent, fever, N/V, chills
- +ve gram stain & culture of diasylate effluent
PD - complication - infectious - peritonitis - types
- sterile culture
- culture -ve: microorganisms stick to bag/peritoneal cavity, miss them when taking specimen
PD - complication - infectious - peritonitis - treatment
- broad spectrum Abx for initial empiric therapy then modify according to culture & sensitivities
PD - complication - infectious - peritonitis - fungal peritonitis
- remove catheter immediately
- treat w azoles (fluconazole), echinocandin (caspofungin), amphotericin B
- anti-fungal during abx to prevent risk (oral nystatin, fluconazole)
PD - complication - infectious - peritonitis - prevention - systemic prophylactic Abx
- immediately before catheter placement even if no infection
- perioperative IV broad spectrum agents: +ve (Cefazolin, Vancomycin), -ve (Gentamacin)
- used before colonoscopy & invasive gynae procedure
PD - complication - infectious - peritonitis - prevention - others
1) avoid/treat hypokalaemia
- reduce peritonitis risk
2) avoid/limit H2RA (formatidine)
- prevent enteric peritonitis
- suppress gastric acid = overgrowth of bacteria
- use PPi instead
3) avoid/treat GI problem (C/enteritis)
- laxative cuz constipation affect outflow of effluent
PD - complication - infectious - peritonitis - treatment - frequency
- 14 - 21 days
- intermittent: 1 large dose into 1 exchange/day, dwell 6h
- continuous: w each exchange
PD - complication - infectious - peritonitis - treatment - initial empiric therapy
- broad spectrum + Adjust
- same as previous
- Cefepime cover both +Ve and -ve so mono Tx possible
PD - complication - infectious - peritonitis - Abx treatment - dose adjustment
- increase dose by 25% empirically in patient w significant residual kidney func (urine output > 100mL/day)
- drug renally excreted
PD - complication - infectious - peritonitis - Abx treatment guidlines
- no long term use to prevent ototoxicity (adjunctive N-acetylcysteine)
- AG & penicillin cannot mix into same bag
- if high WBC/no clinical improvement by 6 days then remove PD catheter, initiate HD, continue IV abx for 2 wk
PD - complication - infectious - catheter related infection - clinical presentation
1) purulent discharge
2) erythema at exit site
3) fever, chills
PD - complication - infectious - catheter related infection - treatment
- empiric Abx treatment
- not as serious as peritonitis so oral Abx possible
PD - complication - infectious - catheter related infection - prevention
- topical Abx/antiseptic at catheter site
PD - complication - medical
1) fluid overload
- rectified by increase ultrafiltration, diuretics if residual kidney function
2) electrolyte abnormalities
- change in Ca, low K
3) malnutrition
- AA/glucose loss, muscle waste, decreased appetite
4) glucose load
- calories from diasylate (dextrose)
- DM exacerbation
- increase insulin requirements cuz continuous absorption of glucose from peritoneal cavity/adsorption of insulin to PVC bag and administration set
5) fibrin formation in diasylate
- fibrinogen secreted into PD -> fibrin formation
- identifying feature: cloudy effluent
- complication: intraperitoneal adhesion, outflow obstruction
- treatment: IP heparin (minimally absorbed cuz high MW so minimal sys SE)
PD vs HD
- PD not as efficient cuz not in direct contact w blood
- no method of regulating blood flow to surface of peritoneal membrane
- no countercurrent blood flow & diasylate
when to initiate dialysis
- Non-DM: GFR < 15 ml/min/1.73m^2
- DM: GFR < 20 ml/min/1.73m^2 (Start earlier cuz progress faster)
- most patient start thwn GFR < 10 or when signs/symptoms of kidney failure present
indication for dialysis
1) chronic dialysis
- azotemia vs uremia
- symp: fatigue, weakness, SOB, mental confusion, N/V, bleeding, loss appetite, itching, cold intolerance, weight gain, neuropathy, uremic breath
- signs: oedema, changes in urine output, abdominal distension, pericardial rub, asterixis, critical lab value (BUN, SCr, K)
2) acute/emergent dialysis
- acid base imbalance, electrolyte imbalance, intoxication, oedema, uremia
