By the end of this chapter, learners will be able to:
1. Understand the indications for renal replacement therapy (RRT).
2. Describe the principles and modalities of hemodialysis (HD).
3. Describe the principles and modalities of peritoneal dialysis (PD).
4. Discuss the benefits, risks, and considerations of kidney transplantation.
5. Compare and contrast the different RRT options.
10.1 Introduction to Renal Replacement Therapy
Renal Replacement Therapy (RRT) encompasses life-sustaining treatments for patients with kidney failure or severe acute kidney injury (AKI) who can no longer maintain fluid, electrolyte, and acid-base balance. RRT aims to remove waste products, excess fluid, and correct electrolyte and acid-base abnormalities, thereby replacing the lost functions of the kidneys.
10.2 Indications for RRT
The decision to initiate RRT is based on clinical signs and symptoms of uremia, rather than solely on GFR values. The classic indications for RRT are often remembered by the AEIOU mnemonic:
•Acidosis: Severe, refractory metabolic acidosis (pH <7.1) that does not respond to medical therapy.
•Electrolyte abnormalities: Severe, refractory hyperkalemia (K+ >6.5 mEq/L) or other life-threatening electrolyte imbalances.
•Intoxications: Overdose with dialyzable drugs or toxins (e.g., lithium, salicylates, methanol, ethylene glycol).
•Overload: Refractory fluid overload leading to pulmonary edema or severe hypertension.
•Uremia: Uremic complications such as encephalopathy, pericarditis, neuropathy, or coagulopathy.
10.3 Hemodialysis (HD)
Hemodialysis is a process that involves diverting the patient’s blood through an external filter (dialyzer or artificial kidney) to remove waste products and excess fluid.
1. Principles of HD
•Diffusion: Movement of solutes from an area of higher concentration (blood) to lower concentration (dialysate) across a semipermeable membrane.
•Ultrafiltration: Removal of excess fluid by applying hydrostatic pressure across the dialyzer membrane.
•Convection: Solute drag, where solutes are carried along with the fluid removed during ultrafiltration.
2. Modalities of HD
•Intermittent Hemodialysis (IHD): Most common form, typically performed 3 times per week for 3-5 hours per session in a dialysis center or at home.
•Daily Hemodialysis: Shorter, more frequent sessions (e.g., 5-7 times per week).
•Nocturnal Hemodialysis: Longer sessions performed overnight, often at home.
3. Vascular Access for HD
•Arteriovenous Fistula (AVF): Created surgically by connecting an artery and a vein. It is the preferred access due to lower infection and thrombosis rates, and longer patency. Requires maturation time (weeks to months).
•Arteriovenous Graft (AVG): Uses a synthetic tube to connect an artery and a vein. Used when AVF is not feasible. Higher risk of infection and thrombosis than AVF.
•Central Venous Catheter (CVC): A temporary or tunneled catheter placed in a large vein (e.g., internal jugular, femoral). Used for immediate access or when AVF/AVG are not ready. Highest risk of infection and thrombosis.
4. Complications of HD
•Hypotension, muscle cramps, nausea/vomiting, headache, disequilibrium syndrome, access-related complications (infection, thrombosis, aneurysm).
10.4 Peritoneal Dialysis (PD)
Peritoneal dialysis uses the patient’s own peritoneal membrane as the semipermeable filter. Dialysate fluid is instilled into the peritoneal cavity, where waste products and excess fluid diffuse across the membrane into the dialysate, which is then drained.
1. Principles of PD
•Diffusion: Solutes move from blood in peritoneal capillaries to dialysate in the peritoneal cavity.
•Ultrafiltration: Achieved by using dextrose (glucose) as an osmotic agent in the dialysate, creating an osmotic gradient that draws water from the blood into the dialysate.
2. Modalities of PD
•Continuous Ambulatory Peritoneal Dialysis (CAPD): Manual exchanges performed by the patient multiple times a day (e.g., 3-5 exchanges/day, 4-6 hours dwell time).
•Automated Peritoneal Dialysis (APD): Performed overnight using a cycler machine, typically 8-10 hours.
3. Peritoneal Access
•A permanent catheter is surgically placed into the peritoneal cavity.
4. Complications of PD
•Peritonitis (infection of the peritoneal cavity, most common and serious complication), catheter-related complications, fluid overload/dehydration, hyperglycemia (from dextrose in dialysate), weight gain, hernia.
10.5 Kidney Transplantation
Kidney transplantation is the surgical placement of a healthy kidney from a donor into a recipient with ESRD. It is considered the optimal RRT option for most eligible patients, offering improved quality of life and longer survival.
1. Types of Donors
•Living Donor: A healthy living person (related or unrelated) donates one of their kidneys. Offers better long-term outcomes and can be planned.
•Deceased Donor: Kidney obtained from a deceased individual (brain-dead or circulatory-dead donor). Allocation is based on a complex system (e.g., UNOS in the US) considering factors like blood type, tissue match, waiting time, and medical urgency.
2. Benefits of Transplantation
•Improved quality of life (freedom from dialysis, fewer dietary restrictions).
•Longer life expectancy.
•Better control of blood pressure, anemia, and bone disease.
•Return to more normal lifestyle, including work and travel.
3. Risks and Complications
•Surgical Risks: Bleeding, infection, vascular complications.
•Immunosuppression: Lifelong need for immunosuppressive medications to prevent rejection. This increases risk of infection, cancer, and other side effects (e.g., diabetes, hypertension, bone disease).
•Rejection: Acute or chronic rejection of the transplanted kidney.
•Recurrence of Original Disease: Some kidney diseases can recur in the transplanted kidney.
4. Transplant Evaluation
•Comprehensive medical, surgical, and psychosocial evaluation to determine suitability for transplantation.
10.6 Comparison of RRT Modalities
| Feature | Hemodialysis (HD) | Peritoneal Dialysis (PD) | Kidney Transplantation |
|---|---|---|---|
| Location | In-center or home | Home | Hospital (surgery) |
| Frequency | 3x/week (IHD) | Daily (CAPD) or overnight (APD) | One-time surgery |
| Access | AVF, AVG, CVC | Peritoneal catheter | Surgical anastomosis |
| Independence | Less (IHD) | More | Most |
| Dietary/Fluid Restrictions | Strict | Moderate | Least |
| Quality of Life | Moderate | Good | Excellent |
| Survival | Moderate | Moderate | Excellent |
| Major Complications | Hypotension, infection, access issues | Peritonitis, catheter issues | Rejection, infection, immunosuppression side effects |
Key Points on Renal Replacement Therapy
1.Indications: AEIOU mnemonic (Acidosis, Electrolytes, Intoxications, Overload, Uremia).
2.Hemodialysis (HD): Blood filtered externally. Requires vascular access (AVF preferred). Complications include hypotension, infection.
3.Peritoneal Dialysis (PD): Peritoneal membrane acts as filter. Home-based. Complications include peritonitis.
4.Kidney Transplantation: Optimal RRT, improved QoL and survival. Requires lifelong immunosuppression. Living or deceased donors.
5.Comparison: Each modality has distinct advantages and disadvantages regarding independence, lifestyle, and complications.
RRT Decision-Making
•Patient preference: Crucial in choosing modality.
•Medical suitability: Co-morbidities, vascular access.
•Social support: Especially for home therapies.
General RRT Pearls
1.Early Referral: Refer patients with progressive CKD to nephrology early for RRT education and planning.
2.Shared Decision-Making: Involve patients and families in choosing the most appropriate RRT modality based on lifestyle, comorbidities, and preferences.
3.Pre-emptive Transplant: Kidney transplantation before initiating dialysis offers the best long-term outcomes.
Hemodialysis Pearls
1.AVF First: Always prioritize arteriovenous fistula creation for hemodialysis access due to superior outcomes.
2.Catheter-Related Infections: Central venous catheters are a major source of infection; remove them as soon as permanent access is ready.
3.Dialysis Disequilibrium Syndrome: More common in initial HD sessions, prevent by starting with shorter, less intensive dialysis.
Peritoneal Dialysis Pearls
1.Peritonitis Prevention: Meticulous sterile technique during exchanges is paramount to prevent peritonitis.
2.Exit Site Care: Proper exit site care is crucial to prevent catheter-related infections.
3.Encourage Home Therapy: PD offers greater flexibility and independence, making it a good option for suitable patients.
Kidney Transplantation Pearls
1.Immunosuppression Adherence: Non-adherence to immunosuppressive medications is a leading cause of graft rejection.
2.Infection Risk: Post-transplant patients are at increased risk of opportunistic infections due to immunosuppression.
3.Cardiovascular Risk: Despite improved outcomes, cardiovascular disease remains a significant cause of morbidity and mortality post-transplant.
Question 1
Which of the following is NOT a classic indication for initiating renal replacement therapy (RRT)? A) Refractory fluid overload B) Severe, refractory hyperkalemia C) Mild nausea and fatigue D) Uremic pericarditis
Answer: C) Mild nausea and fatigue Explanation: Mild nausea and fatigue are symptoms of uremia but are not typically considered urgent indications for RRT unless they are severe or accompanied by other life-threatening complications.
Question 2
Which type of vascular access is considered the preferred option for long-term hemodialysis due to its lower infection and thrombosis rates? A) Central venous catheter B) Arteriovenous graft (AVG) C) Arteriovenous fistula (AVF) D) Peritoneal catheter
Answer: C) Arteriovenous fistula (AVF) Explanation: The AVF is the gold standard for hemodialysis access due to its superior patency and lower complication rates.
Question 3
What is the most common and serious complication of peritoneal dialysis? A) Hypotension B) Muscle cramps C) Peritonitis D) Disequilibrium syndrome
Answer: C) Peritonitis Explanation: Peritonitis, an infection of the peritoneal cavity, is the most frequent and significant complication of peritoneal dialysis.
Question 4
Which of the following is considered the optimal renal replacement therapy option for most eligible patients with ESRD? A) Intermittent hemodialysis B) Continuous ambulatory peritoneal dialysis C) Kidney transplantation D) Nocturnal hemodialysis
Answer: C) Kidney transplantation Explanation: Kidney transplantation offers the best quality of life and longest survival for patients with ESRD.
Question 5
Which of the following is a key principle of hemodialysis that involves the movement of solutes from an area of higher concentration to lower concentration? A) Ultrafiltration B) Convection C) Diffusion D) Osmosis
Answer: C) Diffusion Explanation: Diffusion is the primary mechanism by which waste products move from the patient’s blood into the dialysate across the semipermeable membrane.
Question 6
Lifelong immunosuppressive medication is required for patients undergoing which renal replacement therapy? A) Hemodialysis B) Peritoneal dialysis C) Kidney transplantation D) All of the above
Answer: C) Kidney transplantation Explanation: Immunosuppressive drugs are essential after kidney transplantation to prevent the recipient’s immune system from rejecting the new organ.
Question 7
Which of the following is a benefit of peritoneal dialysis compared to in-center hemodialysis? A) Fewer dietary restrictions B) Greater patient independence and flexibility C) Lower risk of peritonitis D) Faster removal of toxins
Answer: B) Greater patient independence and flexibility Explanation: PD offers patients more control over their treatment schedule and allows for home-based therapy, leading to greater independence.
Question 8
Which of the following is a common complication of hemodialysis, particularly during or immediately after a session? A) Peritonitis B) Hyperglycemia C) Hypotension D) Catheter exit site infection
Answer: C) Hypotension Explanation: Hypotension is a frequent complication during hemodialysis, often due to rapid fluid removal.
Question 9
What is the primary osmotic agent used in peritoneal dialysis dialysate to achieve ultrafiltration? A) Sodium chloride B) Potassium C) Dextrose (glucose) D) Bicarbonate
Answer: C) Dextrose (glucose) Explanation: Dextrose creates an osmotic gradient that draws excess water from the patient’s blood into the dialysate in the peritoneal cavity.
Question 10
Which of the following is a potential long-term risk associated with lifelong immunosuppression after kidney transplantation? A) Decreased risk of infection B) Improved bone density C) Increased risk of certain cancers D) Reduced risk of diabetes
Answer: C) Increased risk of certain cancers Explanation: Long-term immunosuppression increases the risk of various malignancies, including skin cancers and post-transplant lymphoproliferative disorder (PTLD).
Nephrologist’s Kidney-Replacement Framework
Kidney replacement therapy (KRT) should be presented as one component of a broader care plan that includes conservative management, transplant evaluation, home dialysis, intermittent hemodialysis, peritoneal dialysis, and continuous or prolonged therapies. The decision is based on symptoms, complications, metabolic control, volume status, trajectory, prognosis, goals, and feasibility rather than a creatinine or eGFR threshold alone.
Planning Before Kidney Failure
Early planning allows time for education, shared decision-making, transplant referral, vascular preservation, access creation, home assessment, caregiver preparation, vaccination, medication review, and advance-care planning. Patients with progressive CKD should receive modality education before urgent dialysis is likely. The timing of access referral depends on kidney-function trajectory, anatomy, local surgical capacity, and the possibility of pre-emptive transplantation.
| Planning domain | Nephrologist’s assessment | Practical action |
|---|---|---|
| Trajectory | eGFR slope, albuminuria, KFRE risk, recurrent AKI, potassium and bicarbonate trends | Estimate the likelihood and timing of kidney failure without presenting the estimate as certain. |
| Modality | Home support, cognition, dexterity, vision, housing, work, travel, body habitus, prior surgery, and preferences | Offer balanced education on transplant, home HD, PD, in-center HD, and conservative kidney management. |
| Access | Vascular anatomy, prior catheters, cardiac function, expected duration of dialysis, and transplant plans | Preserve veins, avoid unnecessary PICCs, and coordinate access planning with the anticipated treatment pathway. |
| Transplant | Comorbidity, frailty, malignancy, infection, psychosocial readiness, and living-donor potential | Refer early enough for evaluation and consider pre-emptive transplantation where feasible. |
| Goals of care | Life priorities, symptom burden, caregiver capacity, and acceptable treatment burden | Document the patient’s goals and revisit them as health status changes. |
When to Initiate KRT in AKI or Advanced CKD
In AKI, initiate emergent KRT for life-threatening fluid, electrolyte, or acid–base abnormalities that are refractory to medical therapy. In advanced CKD, initiation is usually driven by uremic symptoms or complications, inability to control volume or blood pressure, progressive nutritional deterioration, or refractory metabolic abnormalities. A single eGFR value should not determine initiation in an otherwise stable, asymptomatic patient.
| Indication | Examples | Specialist considerations |
|---|---|---|
| Electrolyte or acid–base emergency | Refractory hyperkalemia, severe acidemia, or rapidly evolving metabolic derangement | Stabilize immediately with medical therapy while arranging KRT; do not delay for a numeric threshold when the clinical risk is high. |
| Fluid or oxygenation failure | Refractory pulmonary edema, severe hypoxemia, or uncontrolled volume-related hypertension | Assess hemodynamics, diuretic response, venous congestion, and whether ultrafiltration can be tolerated. |
| Uremic complications | Encephalopathy, pericarditis, clinically significant bleeding, severe pruritus, nausea, or nutritional decline attributable to uremia | Exclude alternative causes and consider the urgency of treatment, modality, and goals of care. |
| Intoxication | Selected dialyzable toxins such as lithium, methanol, ethylene glycol, or salicylate | Use poison-center or toxicology guidance because clearance depends on toxin, distribution, rebound, and antidote therapy. |
| Progressive kidney failure | Persistent symptoms and complications despite optimized conservative treatment | Plan access and modality before an emergency start whenever possible. |
Intermittent Hemodialysis Prescription
Hemodialysis combines diffusion, convection, and ultrafiltration. The prescription includes treatment time, blood-flow rate, dialysate-flow rate, membrane characteristics, dialysate sodium, potassium, calcium, bicarbonate, temperature, anticoagulation, and ultrafiltration goal. It should be individualized to body size, residual kidney function, catabolic state, vascular access, hemodynamics, and the desired rate of solute and volume removal.
| Prescription component | What it controls | Common specialist pitfalls |
|---|---|---|
| Blood and dialysate flow | Solute clearance and treatment efficiency | Assuming a prescribed flow equals delivered clearance when access recirculation or interruptions occur. |
| Treatment time and frequency | Weekly clearance, volume control, phosphate control, and symptom burden | Using a nominal schedule without accounting for residual kidney function and interdialytic weight gain. |
| Ultrafiltration rate and goal | Net fluid removal and hemodynamic stress | Removing a large volume rapidly without reassessing target weight, refill, nutrition, and cardiac function. |
| Dialysate composition | Potassium, calcium, sodium, bicarbonate, and temperature gradients | Creating arrhythmia, alkalemia, hypocalcemia, or rapid sodium shifts through an inappropriately aggressive bath. |
| Anticoagulation | Prevention of circuit clotting | Failing to adjust for bleeding risk, heparin exposure, thrombocytopenia, or recent procedures. |
Dialysis Adequacy and Volume Management
Dialysis adequacy is multidimensional. Small-solute measures such as single-pool Kt/V or urea reduction ratio should be interpreted alongside treatment time, missed treatments, access function, residual kidney function, nutrition, phosphate, potassium, bicarbonate, anemia, symptoms, blood pressure, and volume status. A technically adequate urea clearance does not prove adequate fluid management or patient-centered treatment.
Dry weight is a clinical estimate, not a fixed number. Reassess blood pressure, edema, lung findings, symptoms, intradialytic hypotension, nutritional status, and trends in bioimpedance or imaging when available. Recurrent intradialytic hypotension should prompt review of ultrafiltration rate, target weight, dialysate temperature and sodium, antihypertensive timing, autonomic dysfunction, cardiac disease, and occult sepsis or bleeding.
Vascular Access
Access choice should follow an individualized life-plan approach rather than a universal fistula-first rule. Autogenous fistula, graft, tunneled catheter, and selected unconventional options each have different maturation times, failure modes, infection risks, and suitability for the patient’s expected dialysis duration. Examine the access before every treatment and investigate changes in thrill, bruit, venous pressures, recirculation, bleeding time, or delivered clearance.
Catheter-related bloodstream infection requires prompt culture collection and antibiotic management according to local protocols, with a decision about catheter salvage, exchange, or removal based on the organism, tunnel involvement, metastatic infection, access options, and hemodynamic stability. Preserve future access sites by avoiding unnecessary central venous devices and venipuncture in planned access limbs.
Peritoneal Dialysis Prescription and Monitoring
Peritoneal dialysis uses the peritoneal membrane for solute and fluid exchange. Prescription variables include fill volume, dwell time, number of exchanges, dextrose concentration, icodextrin use, cycle timing, last fill, and residual kidney function. The prescription should be adjusted for transport characteristics, ultrafiltration, sodium removal, symptoms, nutrition, glycemic effects, and patient lifestyle.
| PD monitoring domain | What to assess | Response to concern |
|---|---|---|
| Peritonitis | Abdominal pain, cloudy effluent, fever, leukocyte count, differential, Gram stain and culture | Collect effluent promptly and begin empiric intraperitoneal therapy according to local and ISPD protocols; do not wait for culture results. |
| Ultrafiltration failure | Weight, edema, blood pressure, urine output, drain volumes, membrane transport, and constipation | Review catheter position, constipation, prescription, glucose exposure, icodextrin suitability, and membrane function. |
| Exit-site or tunnel infection | Drainage, erythema, pain, cuff involvement, and organism | Culture, treat promptly, and assess for catheter removal when refractory or associated with peritonitis. |
| Nutrition and metabolic effects | Protein losses, appetite, glucose exposure, lipids, weight, and residual kidney function | Coordinate dietetic care and tailor glucose load and prescription to the patient’s metabolic profile. |
Continuous and Prolonged KRT
Continuous kidney replacement therapy is often selected for hemodynamically unstable patients, severe fluid overload, cerebral edema risk, or the need for gradual control of solutes. Intermittent HD, prolonged intermittent KRT, and CRRT should be viewed as complementary modalities. Delivered effluent dose is lower than prescribed because of downtime, filter clotting, access problems, and interruptions; dose should therefore be prescribed and audited against the delivered therapy.
Monitor phosphate, potassium, magnesium, calcium, bicarbonate, temperature, nutrition, antimicrobial clearance, and anticoagulation during CRRT. Reassess the indication daily and discontinue or transition when kidney function and hemodynamics permit. Avoid continuing KRT solely because it was started previously when the original indication has resolved.
Kidney Transplantation
Transplantation is the preferred kidney-replacement option for suitable patients because it can improve survival and quality of life compared with remaining on dialysis. Evaluation includes cardiovascular and peripheral vascular assessment, malignancy screening, infection and vaccination review, frailty and functional status, psychosocial readiness, adherence capacity, substance-use assessment, anatomy, recurrence risk of the native kidney disease, and living-donor exploration.
| Transplant phase | Nephrologist-level priorities | Common risks to address |
|---|---|---|
| Candidate evaluation | Comorbidity, frailty, malignancy, infection, immunologic risk, psychosocial support | Unrecognized cardiovascular disease, active infection, incomplete screening, unrealistic expectations, or inadequate support. |
| Perioperative period | Volume, delayed graft function, immunosuppression, thrombosis, infection prophylaxis, and drug interactions | Calcineurin-inhibitor toxicity, acute tubular injury, hyperkalemia, rejection, and medication errors. |
| Long-term graft care | Creatinine and proteinuria trends, blood pressure, metabolic complications, malignancy screening, and adherence | Chronic rejection, recurrent disease, BK virus, CMV, cardiovascular disease, and immunosuppression toxicity. |
| Recurrence counseling | Risk depends on the original disease, phenotype, genetics, and prior response to therapy | Do not assume all native kidney diseases have the same recurrence risk or treatment approach. |
Immunosuppression and Graft Dysfunction
Maintenance immunosuppression commonly combines a calcineurin inhibitor, an antiproliferative agent, and corticosteroid, but the regimen is individualized. A rising creatinine or new proteinuria requires a structured evaluation that includes volume and obstruction, drug levels and interactions, infection, rejection, recurrent disease, thrombotic microangiopathy, and biopsy when indicated. Drug levels should be interpreted with timing, formulation, adherence, albumin, hematocrit, and interacting medications.
Conservative Kidney Management
Conservative kidney management is active, holistic care without dialysis or transplantation as the primary life-prolonging treatment. It includes symptom control, volume and electrolyte management, anemia and acidosis care when consistent with goals, medication simplification, nutrition, psychosocial support, advance-care planning, and coordination with palliative-care services. It should be offered as a legitimate option rather than as an absence of treatment.
Shared Decision-Making and Modality Selection
| Option | Potential strengths | Important limitations or burdens |
|---|---|---|
| In-center HD | Professional support, predictable schedule, rapid solute and fluid removal | Travel, vascular access, hemodynamic stress, post-dialysis fatigue, and limited scheduling flexibility. |
| Home HD | Greater schedule flexibility and potential for more frequent or longer treatments | Training, equipment, caregiver or self-care demands, and home suitability. |
| PD | Home therapy, preservation of residual kidney function, and no vascular access requirement | Peritonitis risk, catheter and abdominal issues, glucose exposure, and daily treatment responsibility. |
| Transplant | Potential survival and quality-of-life benefit with freedom from dialysis | Evaluation delay, surgery, lifelong immunosuppression, rejection, infection, and recurrent disease. |
| Conservative care | Goal-concordant symptom-focused care without treatment burden of KRT | Requires proactive support, careful symptom management, and clear communication about prognosis. |
Clinical Pearls for Nephrologists
Do not start KRT because an eGFR number looks uncomfortable when the patient is clinically stable and complications are controlled. Do not delay urgent therapy while repeatedly calculating a threshold when refractory hyperkalemia, pulmonary edema, severe acidemia, toxin exposure, or uremic complications are present. A dialysis prescription must be audited by delivered treatment, not only the ordered treatment. When the access fails, the patient’s future access plan is part of the emergency.
References
[1] KDIGO. Acute Kidney Injury and Acute Kidney Disease Guideline: https://kdigo.org/guidelines/acute-kidney-injury/
[2] KDIGO. 2024 Clinical Practice Guideline for the Evaluation and Management of CKD: https://kdigo.org/guidelines/ckd-evaluation-and-management/
[3] KDIGO. Evaluation and Management of Candidates for Kidney Transplantation: https://kdigo.org/guidelines/evaluation-and-management-of-candidates-for-kidney-transplantation/
[4] KDIGO. Kidney Transplant Recipient Guideline: https://kdigo.org/guidelines/kidney-transplant-recipient/
[5] KDOQI. Clinical Practice Guideline for Vascular Access: https://www.ajkd.org/article/S0272-6386(19)31137-0/fulltext
[6] KDOQI. Clinical Practice Guideline for Hemodialysis Adequacy: https://www.ajkd.org/article/S0272-6386(14)00825-2/fulltext
[7] International Society for Peritoneal Dialysis. Peritonitis Recommendations: https://journals.sagepub.com/doi/10.1177/08968608231157949