What are the guidelines for initiating and managing hemodialysis in patients with impaired renal function?

Hemodialysis Initiation and Management

Timing of Dialysis Initiation

Dialysis should be initiated when GFR falls below 10 mL/min/1.73 m² in the presence of uremic symptoms or specific clinical complications, not based on GFR alone, as early initiation provides no survival benefit and may cause harm. 1, 2

GFR-Based Thresholds

• Conservative management should continue until GFR <15 mL/min/1.73 m² unless specific clinical indications exist 1
• Target GFR for initiation is approximately 10 mL/min/1.73 m² based on theoretical considerations and historical data 1, 2
• Mean GFR at dialysis initiation is 9.8 mL/min/1.73 m², with lower values (7-9 mL/min/1.73 m²) for young and middle-aged adults and higher values (10-10.5 mL/min/1.73 m²) for children and elderly patients 1, 2
• Early initiation (GFR >10 mL/min/1.73 m²) shows no survival advantage when corrected for lead-time bias and may increase mortality risk 1, 2, 3

Mandatory Clinical Indications for Earlier Initiation

Dialysis must be initiated regardless of GFR when any of the following are present:

• Uremic symptoms: pericarditis, encephalopathy, intractable nausea/vomiting, bleeding diathesis, pruritus 1, 2
• Protein-energy malnutrition that persists despite vigorous dietary optimization with no other apparent cause 1, 2
• Volume overload refractory to diuretic therapy 1, 2
• Uncontrolled hypertension despite maximal medical management 1, 2
• Severe metabolic derangements: refractory metabolic acidosis or hyperkalemia 1, 2
• Progressive nutritional deterioration: declining edema-free body weight, falling serum albumin, lean body mass <63% 1, 2
• Cognitive impairment attributable to uremia 1, 2

Conditions Permitting Delayed Initiation

Dialysis may be safely deferred even when GFR <10 mL/min/1.73 m² if ALL of the following criteria are met:

• Stable or increased edema-free body weight 1, 2
• Adequate nutritional parameters (serum albumin above lower limit of normal and stable/rising) 1, 2
• Lean body mass ≥63% 1, 2
• Complete absence of uremic symptoms 1, 2

Critical Pitfalls in GFR Assessment

When Standard eGFR Equations Are Unreliable

Use measured GFR via 24-hour urine collection for creatinine and urea clearances in the following situations rather than creatinine-based estimating equations 1:

• Unusually low creatinine generation: malnutrition, amputation, muscle-wasting diseases, vegetarian diet, advanced age 1
• Unusually high creatinine generation: bodybuilders, high meat intake 1
• Altered tubular creatinine secretion: cimetidine, trimethoprim use, advanced liver disease 1

Lead-Time Bias Considerations

• Observational data showing better outcomes with early initiation are confounded by lead-time bias 1, 2, 3
• Frailer patients with more comorbidities tend to start dialysis at higher GFR levels but do not live as long as healthier patients who start later—this reflects patient selection, not benefit from early initiation 1, 2
• When properly corrected for lead-time bias, early dialysis initiation shows no survival advantage and potentially increased mortality 1, 2, 3

Initial Dialysis Prescription: "Low and Slow" Approach

The first hemodialysis treatment must use a reduced-intensity protocol to prevent dialysis disequilibrium syndrome, hemodynamic instability, and other acute complications. 4

First Session Parameters

• Duration: 2-2.5 hours (not full 4 hours) 2, 4
• Blood flow rate: 200-250 mL/min 2, 4
• Ultrafiltration: Minimal during first session, focusing on clearance rather than fluid removal 2, 4
• Dose escalation: Gradual increase over subsequent sessions as tolerated 2, 4

Physiological Rationale

• Rapid urea removal creates an osmotic gradient between brain and blood, leading to cerebral edema (dialysis disequilibrium syndrome) 4
• Symptoms include headache, nausea, vomiting, restlessness, seizures, and potentially coma 4
• Risk is highest in patients with very high BUN levels at initiation 4
• Rapid fluid removal causes hypotension, myocardial stunning, arrhythmias, and increased cardiovascular mortality 4

Monitoring During Initial Treatment

• Vital signs every 15-30 minutes during first session 4
• Close observation for neurological symptoms (headache, nausea, confusion) 4
• Assessment of vascular access function and blood flow 4
• Post-dialysis evaluation for delayed complications 4

Ongoing Hemodialysis Adequacy

Dose Measurement and Targets

• Delivered dose must be measured monthly using spKt/V calculated by formal urea kinetic modeling or second-generation natural logarithm formula 1
• Minimum target spKt/V: Values should meet or exceed adult population recommendations 1
• Include treatment frequency in dose expression 1
• Nutritional assessment (nPCR) should be measured monthly 1

Special Considerations

• Residual kidney function (RKF) preservation is critical as HD-related hypotension may accelerate RKF loss 1
• Dialysis is not innocuous and does not replace all kidney functions 1, 2
• Vascular access complications and dialysate-related risks must be considered 1, 2

Pre-Dialysis Planning (Stage 4 CKD)

Education and planning must begin when patients reach CKD stage 4 (GFR <30 mL/min/1.73 m²) to allow adequate preparation. 1

Essential Components

• Comprehensive education about all renal replacement therapy modalities including conservative management 1
• Evaluation for preemptive kidney transplantation (living donor transplant should be considered when GFR <20 mL/min/1.73 m²) 1
• Timely vascular access placement to ensure permanent access at dialysis initiation 1
• Training for home dialysis modalities if appropriate 1
• Discussion of conservative care without dialysis as a valid option 1

Rationale for Early Planning

• Rate of CKD progression is unpredictable 1
• Substantial variability exists in when uremic symptoms appear 1
• Patients require time to assimilate information and make informed decisions 1
• Vascular access procedures have variable success rates and may require months to mature 1
• Uremic cognitive impairment may cloud decision-making if delayed 1

Risks of Dialysis Therapy

Dialysis imposes significant burden and risks that must be weighed against benefits:

• Accelerated loss of residual kidney function from HD-related hypotension 1, 2
• Vascular access complications (infection, thrombosis, steal syndrome) 1, 2
• Dialysate-related complications 1, 2
• Significant burden on patient, family, and healthcare system 1, 2
• Does not replace all kidney functions (endocrine, metabolic) 1