Effect of Protein Intake During Hemodialysis on Blood Pressure and Arterial Stiffness Indices

Acute Effect of Protein Intake During Dialysis on Intradialytic Blood Pressure, 24-hour Ambulatory Blood Pressure and Arterial Stiffness Indices in Maintenance Hemodialysis Patients.

Open label, randomized, cross-over clinical study comparing the acute effect of high versus low protein meals during dialysis on intradialytic blood pressure, 24-hour ambulatory blood pressure and arterial stiffness indices on maintenance hemodialysis patients.

A series of demographic, anthropometric and clinical data will be collected prior to enrollment. The intervention will last 3 consecutive weeks. Eligible subjects will be randomised to one group (high or low protein meals during dialysis) for one week (3 dialysis sessions). Second week will be a wash out period (patients will not consume meals during dialysis) and during the third week randomised subjects will cross over to the other study group. Every meal will provide 1/3 of daily recommended energy and protein intake (35 kcal/kg body weight/day, 0.7 gr protein/kg body weight/day for low protein meals and 1.5 gr protein/kg body weight/day for high protein meals). All the meals will be prepared in the hospital's kitchen and will be personalized to each patient's preferences. The meal will be given one hour after the start of the session and should be consumed completely during dialysis.

Patients will be evaluated for the following parameters during their midweek dialysis session:

1. Intradialytic blood pressure
2. 24-hour ambulatory blood pressure
3. Arterial stiffness indices (Central Aortic blood pressure, Pulse Wave Velocity, Augmentation Index)
4. Hemodialysis adequacy
5. Nutritional status

Intradialytic blood pressure, 24-hour ambulatory blood pressure and arterial stiffness indices will be evaluated with the use of the brachial cuff-based oscillometric device Mobil-O-Graph NG (IEM, Stolberg, Germany). Urea reduction ratio (URR) and Kt/V (standard and equilibrated) will be used as measures for dialysis adequacy. Possible changes in patients nutritional status will be assessed using the Malnutrition-Inflammation Score (MIS).

Inclusion Criteria:

• Patients to have provided informed written consent
• Patients undergoing maintenance hemodialysis for at least 3 months prior to enrollment
• Ability to self-ingest food during the dialysis session

Exclusion Criteria:

• History of malignancy or any other clinical condition associated with very poor prognosis
• Hospitalization for acute myocardial infarction, unstable angina or acute ischemic stroke within the 3 previous months
• Patients receiving parenteral nutrition
• Body mass index (BMI) of >40 kg/m2
• Bilateral functioning or non-functioning arteriovenous fistula (AVF) and/or arteriovenous graft (AVG) used as dialysis access
• Patients with major amputations (eg lower limbs)
• Women during pregnancy or lactation
• Patients with unsuccessful 24-hour ambulatory recording of blood pressure with Mobil-O-Graph device, in accordance with the current European Society of Hypertension Guidelines.