Does Icodextrin (a glucose polymer) improve clearance in Peritoneal Dialysis (PD)?

Icodextrin in Peritoneal Dialysis: Impact on Clearance

Icodextrin does not significantly improve small solute clearance in peritoneal dialysis but enhances ultrafiltration, which indirectly supports overall clearance by allowing for better volume control and potentially extending technique survival.

Mechanism and Effects of Icodextrin

Icodextrin is a high molecular weight glucose polymer used as an alternative osmotic agent to dextrose during long-dwell exchanges in peritoneal dialysis (PD). Unlike conventional glucose-based solutions that work through crystalline osmosis, icodextrin works through colloid osmosis 1. This mechanism provides several advantages:

• Induces sustained ultrafiltration over prolonged (12-16 hour) dwells
• Slower absorption from the peritoneal cavity compared to glucose
• Lower carbohydrate load than medium (2.5%) and strong (4.25%) glucose exchanges

Impact on Clearance Parameters

Small Solute Clearance

• Icodextrin modestly increases peritoneal clearances of creatinine and urea nitrogen compared to 2.5% glucose solution 1
• The increase in clearance is primarily due to convective transport resulting from enhanced ultrafiltration rather than diffusive transport 2

Ultrafiltration Benefits

• Significantly increases net ultrafiltration compared to 1.5% and 2.5% dextrose solutions 3
• Produces ultrafiltration equivalent to 4.25% dextrose solution but with lower glucose exposure 1
• Reduces the incidence of negative net ultrafiltration during long dwells 3
• Particularly effective in patients with high peritoneal transport status 3

Clinical Applications

Icodextrin is most beneficial when used for:

1. Long nocturnal dwell in CAPD patients
2. Long daytime dwell in APD patients
3. Patients with high or high-average peritoneal membrane transport characteristics
4. Patients experiencing fluid overload refractory to conventional glucose solutions

According to the American Journal of Kidney Diseases guidelines, icodextrin has been shown in randomized controlled trials to both increase peritoneal ultrafiltration and decrease extracellular fluid volume when used for the long dwell in PD patients 4.

Volume Management Benefits

The KDIGO guidelines highlight that icodextrin augments peritoneal ultrafiltration compared with standard glucose solutions, with moderate-certainty evidence supporting this benefit 4. This improved volume control can indirectly support overall clearance by:

• Allowing for better management of hypertension
• Reducing the need for hypertonic glucose solutions that may damage the peritoneal membrane
• Extending PD technique survival in patients who would otherwise fail dextrose-based dialysis 5

Practical Implementation

When incorporating icodextrin into a PD prescription:

• Use for the long dwell period (8-16 hours)
• For CAPD: Use during the long nocturnal dwell
• For APD: Use during the long daytime dwell
• Consider combining with amino acid-based solutions in APD to further reduce glucose exposure 6

Limitations and Considerations

• Icodextrin may cause skin rashes in approximately 5.5% of patients (vs 1.7% with glucose) 1
• Serum levels of icodextrin metabolites increase with use 6
• May slightly reduce residual diuresis in some patients 6
• Not designed to replace all glucose-based exchanges, but rather to optimize the long dwell period

Conclusion

While icodextrin does not dramatically improve direct small solute clearance, it provides significant benefits in ultrafiltration and volume control, which indirectly supports overall dialysis adequacy. For patients with inadequate ultrafiltration, high transport characteristics, or those requiring reduced glucose exposure, icodextrin represents an important tool in the PD prescription that can extend technique survival and improve quality of life.