Lesson
Initiation, Modality, and Life Plan
Kidney replacement starts when kidney failure creates an unacceptable clinical burden. Modality choice is a life plan shaped by physiology, access, home, work, support, transplant, and patient goals.
- Clinical indications
- Shared decision-making
- Transplant
- Home therapies
- Conservative care
Symptoms or failed homeostasis
Transplant, home or center dialysis, conservative care
Access, residual function, transitions, and goals
Start for clinical need
Dialysis is initiated for refractory hyperkalemia, acidosis, volume overload, uremic complications, selected dialyzable poisonings, progressive nutritional or functional decline attributable to kidney failure, or another failure of homeostasis. eGFR and BUN inform the trajectory but do not create a universal start threshold.
Compare complete care pathways
Discuss preemptive or subsequent transplant, peritoneal dialysis, home or in-center hemodialysis, incremental strategies when appropriate, and comprehensive conservative kidney management. Explain likely routines, benefits, burdens, access, caregiver needs, travel, work, cost, and emergency backup without steering by clinician convenience.
Build an ESKD Life-Plan
A life plan connects the current modality to future access, transplant, anticipated transitions, vessel preservation, residual kidney function, and patient goals. Avoid blood pressure cuffs, venipuncture, and PICC placement in veins that may be needed for hemodialysis access when feasible.
Prepare without locking the choice
Early education and access planning reduce crisis starts, but preferences and health change. Revisit modality after hospitalization, loss of function, caregiver change, access failure, transplant evaluation, or treatment burden. An urgent start should not permanently determine the long-term modality.
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Lesson
Solute, Fluid, and Dose Mechanics
Diffusion, convection, adsorption, and ultrafiltration remove different targets. Delivered therapy depends on blood and dialysate flow, membrane, time, access, distribution, residual function, and interruptions.
- Diffusion
- Convection
- Ultrafiltration
- Kt/V
- Residual kidney function
Small solute crosses a membrane
Solute travels with filtered water
Net water leaves the circulation
Match mechanism to target
Diffusion moves small solutes down a concentration gradient and dominates conventional hemodialysis urea clearance. Convection carries solute with plasma water and improves middle-molecule removal when replacement and filtration are designed for it. Adsorption contributes for selected membranes and toxins.
Separate solute from fluid removal
Ultrafiltration removes plasma water through a transmembrane pressure gradient. The prescribed volume must account for intake, urine, target weight, edema, pressure, and treatment duration. A high ultrafiltration rate can produce cramps, hypotension, myocardial stress, loss of residual function, and incomplete treatment.
Understand Kt/V
Kt/V is dialyzer or peritoneal clearance K multiplied by treatment time t and divided by the urea distribution volume V. It is a dimensionless small-solute dose marker. It does not directly measure volume control, middle molecules, nutrition, access health, symptoms, or every patient-valued outcome.
Protect residual function
Residual kidney clearance can contribute meaningfully to solute, potassium, phosphate, and volume control. Avoid unnecessary hypotension and nephrotoxins, measure residual urine and clearance when it changes prescription, and update medication dosing as native function changes.
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Lesson
Hemodialysis Prescription
Hemodialysis delivery is a coupled system of access, blood flow, dialysate, membrane, duration, frequency, anticoagulation, and ultrafiltration. A prescription is only successful when the delivered treatment meets the goal.
- Blood and dialysate flow
- Membrane and time
- Dialysate composition
- Ultrafiltration rate
- Anticoagulation
Access and pump bring solute to the membrane
Composition, flow, area, and time determine transfer
Fluid goal, pressure, anticoagulation, and recovery
Design for clearance and tolerance
Small-solute clearance rises with effective blood flow, dialysate flow, membrane performance, and time, but gains can plateau. Longer or more frequent treatment can improve volume and phosphate control and reduce the ultrafiltration rate. Access recirculation and interruptions reduce delivered dose.
Prescribe dialysate intentionally
Dialysate potassium, calcium, bicarbonate, sodium, glucose, and temperature change arrhythmia, pressure, mineral, and acid-base risk. Avoid automatic one-size prescriptions. Review predialysis and postdialysis patterns, medications, nutrition, ECG risk, and the concentration gradient.
Set a safe fluid goal
Estimate target weight from longitudinal symptoms, pressure, examination, lung and cardiac context, nutrition, and recovery after treatment. Calculate required ultrafiltration across available time. Extend time, increase frequency, reduce sodium exposure, or reassess target rather than repeatedly forcing an intolerable rate.
Verify delivered therapy
Review treatment time, missed or shortened sessions, blood flow, access pressures, alarms, clotting, Kt/V or urea reduction ratio, symptoms, potassium, bicarbonate, phosphate, weight, pressure, and recovery time. A nominal prescription cannot substitute for delivered treatment.
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Lesson
Peritoneal Dialysis Prescription
Peritoneal dialysis uses the peritoneal membrane, dialysate osmotic gradient, exchange volume, dwell time, and frequency to provide continuous solute and fluid removal at home.
- CAPD and APD
- Dwell and exchange
- Dextrose and icodextrin
- Membrane transport
- Residual function
Glucose or icodextrin creates osmotic force
Solute equilibrates as the gradient evolves
Effluent, ultrafiltration, symptoms, and clearance
Build an exchange
Each exchange has drain, fill, dwell, and drainage phases. CAPD uses manual daytime exchanges, while APD commonly uses a cycler overnight. Prescription depends on body size, membrane transport, residual kidney function, lifestyle, glucose exposure, volume, and clearance goals.
Use dwell time and osmotic force
Small-solute equilibration increases with dwell time, while glucose-driven ultrafiltration can dissipate as glucose is absorbed. Higher dextrose increases early fluid removal but also glucose exposure and membrane stress. Icodextrin can support long-dwell ultrafiltration in appropriate patients.
Interpret membrane transport
A peritoneal equilibration test characterizes solute transport and helps align dwell length and modality. Faster transport can favor shorter dwells for ultrafiltration, while slower transport may require longer contact for solute equilibration. Clinical response remains essential.
Measure total therapy
Assess residual and peritoneal clearance, urine and ultrafiltration volume, symptoms, nutrition, potassium, bicarbonate, phosphate, pressure, edema, glucose, catheter function, adherence, and patient experience. More exchanges are not automatically better if burden rises without meaningful benefit.
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Lesson
Continuous and Hybrid Kidney Replacement
CRRT and prolonged intermittent therapies spread fluid and solute removal across more time. They can improve physiologic tolerance in selected critically ill patients, but modality alone has not established a survival advantage.
- CRRT and prolonged intermittent therapy
- CVVH, CVVHD, and CVVHDF
- Effluent dose
- Circuit anticoagulation
- Dynamic medication dosing
CVVHD moves small solute down a gradient
CVVH carries solute with filtered plasma water
CVVHDF joins both modes and requires downtime audit
Choose time and intensity deliberately
CRRT is physiologically attractive when unstable pressure, difficult fluid balance, or increased intracranial pressure makes rapid intermittent shifts undesirable. Prolonged intermittent therapy offers an intermediate duration. Randomized evidence has not shown that continuous therapy itself improves survival or kidney recovery, so patient physiology and reliable delivery should drive selection.
Name the transport mode
CVVH emphasizes convection through replacement-fluid-supported hemofiltration. CVVHD emphasizes diffusion through dialysate flow. CVVHDF combines diffusive and convective clearance. Slow continuous ultrafiltration primarily targets fluid. The acronym is less important than tracing blood flow, dialysate, replacement fluid, effluent, and net patient fluid removal.
Prescribe delivered effluent
For adults receiving CRRT for AKI, current KDIGO guidance supports a delivered effluent volume of 20 to 25 mL/kg/h rather than augmented intensity for small-solute clearance. Interruptions, filter clotting, procedures, and downtime reduce delivery, so the ordered rate may need a margin and the actual delivered dose must be audited.
Prevent treatment-created deficits
Monitor temperature, pressure, acid-base status, sodium, potassium, phosphate, magnesium, calcium, glucose, nutrition, bleeding, citrate balance when used, and circuit life. CRRT can continuously remove medicines and nutrients. Recalculate antimicrobial and other narrow-index regimens whenever effluent rate, downtime, residual kidney function, or modality changes.
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Lesson
Access, Infection, and Acute Complications
Vascular and peritoneal access are lifelines and infection portals. Complications require rapid recognition, cultures or imaging when indicated, source control, treatment, and a plan to preserve future access.
- AV fistula and graft
- Central venous catheter
- PD catheter
- Peritonitis
- Disequilibrium and hypotension
Thrill, bruit, pressure, bleeding, swelling, fever
Exit site, drainage, cloudy fluid, abdominal pain
Hypotension, arrhythmia, hemolysis, air, disequilibrium
Choose access within the life plan
An AV fistula, AV graft, or central venous catheter can each be appropriate in a particular patient and time horizon. Consider vessel anatomy, expected use, maturation, prior access, heart function, infection risk, urgency, transplant, and patient preference rather than applying fistula-first without context.
Protect and examine vascular access
Inspect, palpate, and auscultate before treatment. New loss or change of thrill, prolonged bleeding, difficult cannulation, high pressures, inadequate blood flow, arm swelling, hand ischemia, aneurysm, pain, redness, drainage, or fever requires prompt evaluation. Clinical indicators, not surveillance numbers alone, drive intervention.
Treat suspected PD peritonitis promptly
Cloudy effluent or abdominal pain should trigger effluent cell count, differential, Gram stain, and culture, followed by prompt empiric intraperitoneal antibiotics covering gram-positive and gram-negative organisms according to local patterns. Review technique, exit site, tunnel, recent procedures, fungal risk, and catheter-removal indications.
Recognize treatment emergencies
Intradialytic hypotension, arrhythmia, hemolysis, air embolism, dialyzer reaction, access hemorrhage, disequilibrium, and severe electrolyte shift require immediate protocol-based action. Disequilibrium risk is greatest with severe azotemia and rapid initial clearance, so early prescriptions may require slower, shorter treatment.
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Lesson
Medications, Adequacy, and Transitions
Kidney replacement changes clearance but does not erase native function, nonrenal elimination, protein binding, or distribution. Adequacy includes symptoms, volume, access, nutrition, function, and the person's own goals.
- Dialyzability
- Dose timing
- Therapeutic monitoring
- Goal-directed adequacy
- Modality transitions
Clearance, timing, medication removal, and levels
Time, access, interruptions, adherence, and support
Hospital, recovery, transplant, modality, and goals
Predict dialyzability
Small molecular size, low protein binding, small volume of distribution, water solubility, and significant kidney clearance favor hemodialysis removal. Membrane, blood and dialysate flows, time, and residual function also matter. Peritoneal clearance is slower and continuous, and CRRT prescriptions differ from maintenance dialysis.
Separate loading, maintenance, and replacement
Loading dose is driven mainly by distribution and may not require reduction. Maintenance depends on total clearance. A post-hemodialysis supplemental dose is needed only when clinically important drug is removed. Verify the exact modality schedule and use concentrations when available for narrow-index therapy.
Define adequacy around goals
Kt/V and clearance are necessary measures but do not capture recovery time, cognition, sleep, work, symptoms, mobility, volume, access pain, treatment burden, or caregiver impact. Set patient-prioritized goals and change duration, frequency, modality, symptom care, or support when the treatment is technically adequate but life is not.
Manage every transition
Hospitalization, AKI recovery, loss of residual function, access failure, peritonitis, transplant, travel, pregnancy, caregiver change, and patient preference can alter treatment. Reconcile doses, update target weight and prescription, preserve future access, communicate the plan, and revisit goals after each transition.
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Module practice
Check the connections.
Each attempt draws 10 questions from the complete 120 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.
- KDIGO Dialysis Initiation, Modality, Access, and Prescription Report
- KDIGO Acute Kidney Injury and Acute Kidney Disease Guideline Suite
- KDIGO Home Dialysis Conference Report
- KDOQI Vascular Access Guideline and Tools
- ISPD Guidelines and Educational Resources
- KDIGO Symptom-Based Dialysis Complications
- DailyMed Current Medication Labeling