Renal failure is a relevant condition as the incidence of patients treated with intermittent dialysis continues to grow each year. One of the strongest predictors of mortality in these patients is Protein-Energy Wasting (PEW). Optimal nutritional support, combined with physical exercise may be able to improve the physical condition objectified as muscle wasting and weakness. Correct nutritional support must aim to supplement the correct combination of protein and caloric needs. Although no other way exist than predicting formula to assess protein need, predicting formula don't seem to capture the individual caloric need of the patients. The gold standard to assess caloric need by measuring Resting Energy Expenditure (REE) is indirect calorimetry. Even when caloric and protein targets are defined, intake remains a challenge because of intake restriction in dietary patterns. This is why intradialytic parenteral nutrition (IDPN) can play an crucial role for closing the nutritional gap. Whether IDPN guided by indirect calorimetric measurements of metabolism can close the gap when oral intake fails, remains an unanswered question.

Renal failure is a relevant condition as the incidence of patients treated with renal replacement therapy and specifically intermittent dialysis, continues to grow each year. In 2021 up to 4845 patients required intermittent dialysis in Flanders, Belgium. Weight loss and homeostatic disturbances of energy and protein balances are often present in Chronic Kidney disease (CKD) and end-stage renal disease (ESRD).The international society of renal nutrition and metabolism defines Protein-Energy Wasting (PEW) as the state of nutritional and metabolic disorders in patients with CKD and ESRD, characterized by simultaneous loss of systemic body protein and energy stores. PEW is one of the strongest predictors of mortality in CKD patients. Up tot 54% of adults undergoing chronic intermittent haemodialysis (IHD) suffer from PEW due to a combination of the disease and therapy. Adequate nutritional therapy can reverse the negative impact of PEW. Optimal nutritional support, next to physical exercise may be able to improve the physical condition objectified as muscle wasting and weakness. Correct nutritional support must aim to supplement the correct combination of protein and caloric after assessing the needs and intake of different nutrients. Although no other way exist than predicting formula to assess protein need, predicting formula don't seem to capture the individual caloric need of the patients. The gold standard to assess caloric need by measuring Resting Energy Expenditure (REE) is indirect calorimetry. This technique measures the individual VCO2 and VO2 and after integrating it into the Weir equation it calculates REE. Even when caloric and protein target are defined, intake remains a challenge because of intake restriction in dietary patterns. This is why intradialytic parenteral nutrition (IDPN) can play an crucial role for closing the nutritional gap. In clinical practice, in 38% of dialysis patients, IDPN is used. The most common IDPN were triple phase bags. Whether IDPN guided by indirect calorimetric measurements of metabolism can close the gap when oral intake fails, remains an unanswered question.

Inclusion Criteria:

• Patient on intermittent hemodialysis
• Protein-Energy Wasting defined as 5% within 3 months or 10% within 6 months (not due to water loss, established at the discretion of the treating physician)

Exclusion Criteria:

• Pregnancy
• Contra-indications for the use of indirect calorimetry as stated by the AARC (oxygen therapy for COPD,...)
• Metabolic diseases