Dialysis Flashcards
List steps of water purification for dialysis
- Pretreatment
- Filtration, softening, pH neutralization
- Sediment filter – removes particulate matter such as clay, sand, sediment, contains multiple layers with variable pore sizes
- Carbon filter – removes chlorine, sediment, volatile organic compounds via adsorption
- Water softener – removes calcium and magnesium
- Filtration, softening, pH neutralization
- Purification – removes inorganic solute and bacteria and endotoxins
- Reverse osmosis
- Deionization
- Safety standards and monitoring – endotoxin retaining filter – reduce levels of bacterial fragments and endotoxins
- Distribution
What are the types of PD membrane failure?
- UF Failure – transition to high transporter
- due to increase in membrane vascularity and effective surface area (as a result of glucose exposure, bioincompatible PD solutions, peritonitis episodes, systemic inflammation with uremia
- Loss of aquaporin
- Loss of membrane surface area
- due to adhesions and scarring after severe peritonitis or other intra-abdominal complication or peritoneal sclerosis
- Lymphatic reabsorption of dialysate
Management of restless legs in dialysis patients
- Exercise, stretching
- Reduce caffeine intake
- Reduce/avoid meds associated with RLS (SSRIs, antidepressants)
- Treat iron deficiency
- Increase dialysis
- Dopamine agonists - pramipexole, ropinerole
- Alpha 2 delta calcium channel ligands - gabapentin, pregabalin
- Levodopa
- Benzodiazepines
What are biocompatible PD solutions?
List 3 reasons for and 2 reasons against the use of these solutions
Neutral pH, low glucose degradation product (GDP) solutions
For: preservation of kidney fxn, preserve urine output, help with inflow pain assoc with low pH solutions for some patients(?)
Against: No effect on technique survival, no effect on mortality, increased cost
What are the differences in clinical presentation and physical exam findings for inflow stenosis, outflow stenosis, and central vein stenosis?
See attached.
Also:
- Augmentation test - poor in inflow stenosis, good in outflow stenosis
- Arm elevation test: normal or accentuated collapse in inflow stenosis, no colapse in outflow stenosis
Risk factors for DDS?
Extremes of age
First run
High urea >60
Pre-existing neurologic diseases (head trauma, stroke, seizure disorder)
Concomitant presence of other conditions that could be associated with cerebral edema (such as hyponatremia, hepatic encephalopathy, or hypertensive emergency)
Concomitant presence of another condition associated with increased permeability of the blood-brain barrier (such as sepsis, vasculitis, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, encephalitis, or meningitis)
What did the IDEAL trial show?
- Early vs. late start HD (NEJM 2010)
- 828 adults randomized to start HD when GFR 10-14 or 5-7.
- No difference in survival or clinical outcomes between the groups.
Mechanical vs. non-mechanical complications in PD
- A)Mechanical
- Clot
- Omental wrap
- Leak
- B) Non-mechanical
- Infection
- Eosinophilic allergic reaction
How do you perform a PET test?
- Night dwell must be 8-12 hours. At start of test, drain night dwell over 20 minutes while sitting. Then instill 2L 2.5% dextrose dialysate over 10 minutes while supine, rolling side to side every 2 minutes.
- Once infused, obtain time 0h dialysate samples for glucose, urea, and creatinine
- At 2h obtain dialysate AND plasma samples for glucose, urea, and creatinine
- At 4h, obtain dialysate samples for glucose, urea, and creatinine
- Drain out dialysate over 20 minutes while sitting
- Measure drain volume
- Calculate:
- D/P Cr and plot over time (T0, T2, T4)
- D/D0 Glucose and plot over time (T0, T2, T4)
How do you interpret a PET test?
- High D/P Cr, high D/P urea, low D/D0 glucose):
- High transporter
- Low D/P Cr, low D/P urea, high D/D0 glucose)
- Low transporter
- D/PCr
- >0.83 - High
- 0.65-0.82 - High average
- 0.5-0.62 - Low average
- <0.5 - Low
What is the modified PET test for UF failure
2L of 4.25% - if in 4 hours they don’t UF >400mL, they have UFF. (4/4/4 rule)
DDx for bloody peritoneal dialysate?
- DDx bloody dialysate
- Menstrual bleeding
- Encapsulating peritoneal sclerosis (important not-to-miss, consider if >1 year PD)
- Intra-abdominal or retroperitoneal pathology
- Splenic rupture/infarct, liver carcinomatosis/rupture, iliopsoas hematoma, bleeding from outer uterine wall in a pregnant patient, spontaneous rectal sheath hematoma
- Renal tumors, renal cyst rupture, retroperitoneal hematoma
- Catheter-related post-insertion
Management of bloody dialysate
- Investigate cause
- Instil heparin in the dialysate to prevent clotting in the peritoneal catheter (not systemically absorbed so it will not increase risk of bleeding).
- Perform 2-3 rapid exchanges with room temp dialysate to cause peritoneal vasoconstriction and decrease bleeding.
- Stop antiplatelet/anticoagulants if it’s reasonable to do so.
DDx eosinophilic peritonitis
- Bacterial peritonitis
- Fungal/parasitic peritonitis
- Chemical peritonitis, allergic reaction to some component of the PD system (plastics in the catheter, additives like heparin, antibiotics or dialysis bag, dialysis fluid itself)
- Icodextrin
- Systemic eosinophilia/eosinophilia of effluent eg. hypereosinophilic syndrome
- Malignancy
- Pneumoperitoneum (laparoscopic surgeries)
Risk factors for ESP
- Duration of peritoneal dialysis
- Severe peritonitis, or recurrent and fungal
- Higher dialysate glucose concentrations, use of acetate as dialysate buffer, bioincompatible dialysate?
- UF failure
- Drugs – Bb, CNIs
Management of ESP
- Steroids in inflammatory phase (eg. pred 40 mg daily x 4 months then taper)
- Anti-fibrotic (tamoxifen)
- Rest the peritoneum (4-12 weeks, depending on symptoms)
- Transition to HD or dual-modality PD/HD (symptoms may worsen after stopping PD)
- Parenteral nutritional support
- Surgery (adhesion lysis and excision of peritoneum) if acute obstruction
Problems for high transporter vs. low transporter
- Hyperglycemia, dyslipidemia, truncal obesity
- Ultrafiltration
- More exposure to glucose-based dialysate due to more frequent exchanges
- Higher dialysate protein losses (lower serum albumin)
- Poor phosphate clearance (requires longer dwell times)
What are biocompatible PD solutions?
- Neutral pH, low glucose degradation product (GDP) solutions
Possible pros and cons for biocompatible PD solutions?
- Pros: preservation of kidney fxn, preserve urine output, help with inflow pain assoc with low pH solutions for some patients(?)
- Cons: No effect on technique survival, no effect on mortality, increased cost
List reasons/clinical findings you would want to intervene/investgate fistula
- Shiny skin
- Non-healing ulcer or eschar
- Prolonged bleeding post-dialysis
- Increasing pain
- Rapid expansion in size
- Steal syndrome
- High-output heart failure
List strategies to preserve vascular access
- Avoid peripheral blood draws (use dorsum of the hand whenever possible)
- Avoid PICC lines and midline catheters
- Avoid central lines, especially subclavian lines
- Avoid arterial cannulation of radial and brachial arteries (use other sites if needed for cardiac and other endovascular interventions)
- Avoid cardiac implantable devices (can affect patency of the central veins, and increase longterm risk of infection). Consider epicardial or subcutaneous lead placement.
How does ischemic monomelic neuropathy present?
Who is at risk?
- Immediate onset after the AVF creation (pain, numbness), due to axonal nerve injury from ischemia
- Significantly more likely to occur in patients who have vascular access creation with brachial artery inflow
Ischemic monomelic neuropathy vs. steal?
- In contrast to typical steal, patients with IMN have profound motor and sensory deficits without other associated manifestations of tissue ischemia such as tissue loss.
How to diagnose ischemic monomelic neuropathy and manage?
- In contrast to typical steal, patients with IMN have profound motor and sensory deficits without other associated manifestations of tissue ischemia such as tissue loss.
- Needs immediate ligation
Causes of hypercalcemia in dialysis patients (other than meds)
- Tertiary hyperparathyroidism
- High calcium dialysate bath
- Non-PTH mediated hypercalcemia
- Multiple myeloma
- Bone metastases/malignancy
- Sarcoidosis
- Lymphoma
- Endocrine – hyper/hypothyroid, adrenal insufficiency
Side effect of ESA
- Access thrombosis
- CV events (MI/stroke)
- Hypertension
- ?malignancy
What is a filtration fraction?
Fraction of plasma removed by ultrafiltration
FF = (UF rate x 100) / Qp
where Qp = filter plasma flow rate (ml/min)
Qp = Qb x(1 - Hct)
A filtration fraction of <30% limits haemoconcentration. Increasing the blood pump speed (Qb) will reduce the filtration fraction (aim for 20-30%) and make filter clotting less likely.
What is an icodextrin solution?
- A polyglucose solution, iso-osmolar and induces ultrafiltration by itsoncotic effect.
- Absorption of polyglucose is by the lymphatics and so is much slower compared with glucose.
- The oncotic effect and the associated ultrafiltration are therefore more sustained than with glucose.
Advantages of icodextrin solutions
Indications to use icodextrin?
Advantages:
- Better UF
- Better glycemic control, less weight gain, less dyslipidemia
- Potential preservation of membrane (less glucose exposure)
Indications:
- Long dwell exchanges
- Type 1 UF failure
- Diabetics
- CHF
Advantages of short daily dialysis over conventional dialysis?
- LVH regression
- Better BP control
- Better volume control and hemodynamic stability on HD
- Better small molecule clearance
- Quality of life
Components of CRRT orders
- Mode of CRRT - CVVHDF, CVVH
- Dialyzer choice - ST140
- Dose of dialysis - 25-30 mL/kg/hr
- Access
- Qb 150-180 mL/min
- Qd, Qr - split dose of dialysis, (mL/hr)
- % Pre-filter or post-filter
- Replacement fluid choice - choose K and Ca
- Fluid balance goal
- Anticoagulation - citrate (140-180mL/hr) with post-filter Ca infusion, or heparin (250-500 U/hr) per protocol
- Lab monitoring - q6h lytes and iCa, daily Mg, phos, Cr, urea, albumin
Causes of prolonged AVF bleeding after dialysis?
- Outflow stenosis
- Aneurysm
- Anticoagulation
- Underlying bleeding disorder
- Uremia
- Traumatic needling
Management of HIT in dialysis patient?
- Stop heparin during dialysis
- Note in chart to prevent heparin locks at end. Citrate lock instead.
- Increase Qb
- Saline flush during HD
- Consider HDF with prefilter replacement
- Evaluate for thrombosis
- Argatroban or bivalirudin
Causes of intradialytic hypertension?
- Volume overload
- Hyperactive renin-angiotensin system in response to fluid removal
- ESA given during HD
- High sodium dialysate
- Removal of antihypertensives during dialysis
Treatment of intradialytic hypertension?
Optimize target weight
Clonidine or captopril post-HD if SBP >180
List consequences of intradialytic hypotension
- Increased mortality
- Decreased cardiac function/myocardial stunning
- Vascular access thrombosis
- Decline in residual renal function
- Volume overload
- CVA, cognitive impairment
- GI hypoperfusion
- Symptoms- cramping, N/V
Pros and Cons of AVF
- Pros
- Less infection
- Associated with less mortality
- More reliable Qb
- Longer patency
- Cons
- Time to mature
- Not able to create in all patients
- High output HF
- Steal syndrome
Pros and Cons of CVC
- Pros
- Immediate use
- Ease of insertion
- May be only possible access
- Cons
- Increased risk of infection
- Associated with higher mortality
Why PD over HD?
- Maintain vascular access for the future
- May provide higher likelihood of preserved renal function
- Better hemodynamic stability (eg. cardiorenal)
- Less exposure to anticoagulation
- More independence, quality of life, easier to travel
- Improved LV mass
- Less dietary restrictions
How to increase AVF use in your dialysis program?
- Vascular access preservation strategies
- Early surgical referral
- Vascular mapping to optimize AVF maturation
- Proper maintenance care to prevent failure (eg. thrombosis)
Immediate management of type A dialyzer reaction
- Do not return blood
- Bolus fluid
- Epi IM (0.5mg or 0.1mg IV)
- Benadryl
- Ranitidine
- Steroids
Prevention of type A dialyzer reaction
- Avoid ethylene oxide to sterilize membrane
- Sterilization methods – gamma radiation, steam, electron beam
- Avoid AN69 with ACEi membrane
- Monitor dialysis solution
- Make sure it’s not contaminated
- Avoid heparin at HD
- Switch to a different membrane
- Rinse the circuit
Features of amyloidosis in a dialysis patient
- Carpal Tunnel
- Scapulohumeral periarthritis
- Flexor tenosynovitis
- Destructive spondyloarthropathy
- Bone cysts
- Visceral
- Especially GI tract
- Cardiac (Rare)
- Peripheral neuropathy
- Macroglossia and difficult swallowing