Intradialytic parenteral nutrition improves protein and energy homeostasis in chronic hemodialysis patients

Abstract

Decreased dietary protein intake and hemodialysis-associated protein catabolism are among several factors that predispose chronic hemodialysis (CHD) patients to protein calorie malnutrition. Since attempts to increase protein intake by dietary counseling are usually ineffective, intradialytic parenteral nutrition (IDPN) has been proposed as a potential therapeutic approach in malnourished CHD patients. In this study, we examined protein and energy homeostasis during hemodialysis in seven CHD patients at two separate hemodialysis sessions, with and without IDPN administration. Patients were studied 2 hours before, during, and 2 hours following a hemodialysis session, using a primed constant infusion of L-(1-(13)C) leucine and L-(ring-(2)H(5)) phenylalanine. Our results showed that IPDN promoted a large increase in whole-body protein synthesis and a significant decrease in whole-body proteolysis, along with a significant increase in forearm muscle protein synthesis. The net result was a change from an essentially catabolic state to a highly positive protein balance, both in whole-body and forearm muscle compartments. We conclude that the provision of calories and amino acids during hemodialysis with IDPN acutely reverses the net negative whole-body and forearm muscle protein balances, demonstrating a need for long-term clinical trials evaluating IDPN in malnourished CHD patients.

Figures

Figure 1

Schematic diagram of the metabolic study-day protocol. Arrowheads denote time points for blood draws, breath sample collections, and muscle plasma flow measurements. A primed-constant infusion of L-(1-13C) leucine and L-(ring-2H5) phenylalanine was maintained throughout the entire study (360 minutes).

Figure 2

Plasma enrichment of phenylalanine (Phe) and KIC comparing CTL and IDPN. Diamonds denote phenylalanine enrichment during IDPN protocol, squares denote phenylalanine enrichment during CTL protocol, triangles denote KIC enrichment during IDPN protocol, and plus sign denotes KIC enrichment during CTL protocol.

Figure 3

Plasma AA concentrations over the study period, comparing CTL and treatment (IDPN) protocols. Units are micromoles per liter.

Figure 4

Forearm balance of AAs (by groups) during HD comparing CTL and IDPN. Units are nanomoles per 100 ml per minute.

Figure 5

Whole-body protein components during HD, comparing control (white bars) and IDPN (black bars). Units are in milligrams per kilogram of FFM per minute. Significant differences were observed for all components of whole-body protein homeostasis during this period. There were no differences during predialysis or postdialysis periods (refer to Table 3).