What is the relationship between nitrogen balance, nutrition, edema, and the effectiveness of peritoneal dialysis (PD) in patients with impaired renal function?

From the Guidelines

Maintaining proper nitrogen balance is essential for patients on peritoneal dialysis, as it directly impacts nutritional status, edema management, and overall dialysis effectiveness, with a recommended dietary protein intake of 1.2-1.3 g/kg/day to achieve positive nitrogen balance, as supported by the most recent and highest quality study 1. The relationship between nitrogen balance, nutrition, edema, and peritoneal dialysis effectiveness is complex and multifaceted. Patients on peritoneal dialysis should consume 1.2-1.3 g/kg/day of protein to achieve positive nitrogen balance while managing their condition, as inadequate protein intake leads to negative nitrogen balance, causing muscle wasting and poor wound healing, while excessive protein can burden the kidneys and worsen uremia 1.

Key Considerations

• Nutritional management should include sufficient caloric intake (30-35 kcal/kg/day) with appropriate protein distribution throughout meals, along with monitoring of albumin levels (target >3.5 g/dL) 1.
• Edema in peritoneal dialysis patients often results from fluid overload due to inadequate ultrafiltration or excessive sodium intake, which can compromise dialysis efficiency, and can be managed by restricting sodium intake to 2-3 g/day, limiting fluid intake to 1-1.5 L/day plus urine output, and optimizing dialysis prescriptions with appropriate dwell times and glucose concentrations in dialysate 1.
• Regular monitoring of weight, blood pressure, and residual renal function helps maintain the delicate balance between adequate nutrition and fluid status.
• Peritoneal dialysis effectiveness depends on maintaining peritoneal membrane integrity, preventing protein loss through the dialysate (which can reach 5-15 g/day), and adjusting dialysis prescriptions based on peritoneal equilibration tests to optimize solute clearance and ultrafiltration 1.

Recommendations

• Patients should strive to achieve an nPNA of at least 0.9 g/kg/day in adult PD patients, with individualized recommendations for dietary protein intake benefiting from measurement of dialysate protein losses in children 1.
• PNA values at this level or higher are likely to be associated with neutral or positive nitrogen balance in the absence of significant comorbidity or dialysate protein losses 1.

From the Research

Relationship Between Nitrogen Balance, Nutrition, Edema, and Peritoneal Dialysis Effectiveness

• The effectiveness of peritoneal dialysis is influenced by various factors, including fluid balance, electrolyte management, and nutrition 2.
• Nitrogen balance is an important aspect of nutrition in peritoneal dialysis patients, as it affects the overall health and well-being of the patient 3.
• Edema is a common complication in peritoneal dialysis patients, and it is often related to fluid overload and electrolyte imbalances 4, 5.
• Peritoneal dialysis can be an effective treatment for fluid overload and edema, especially in infants and children 6, 5.

Factors Affecting Peritoneal Dialysis Effectiveness

• Residual renal function (RRF) is an important factor in peritoneal dialysis effectiveness, as it affects the patient's ability to remove waste products and excess fluids 4.
• The use of diuretics, such as furosemide, can help improve fluid balance and reduce edema in peritoneal dialysis patients, but its effectiveness may vary depending on the individual patient 4, 5.
• Nutrition and dietary management are crucial in maintaining a healthy nitrogen balance and preventing malnutrition in peritoneal dialysis patients 2, 3.
• The type of peritoneal dialysis used, such as continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD), can affect the patient's fluid balance and electrolyte management 3.

Clinical Implications

• Peritoneal dialysis can be a safe and effective treatment for fluid overload and edema in infants and children, especially when compared to diuretic administration 5.
• The use of peritoneal dialysis should be strongly considered in patients at high risk for postoperative acute kidney injury and fluid overload 5.
• Regular monitoring of fluid balance, electrolyte levels, and nitrogen balance is essential in peritoneal dialysis patients to prevent complications and ensure optimal treatment outcomes 2, 4, 6, 3.