Peritoneal Transport during Dialysis with Amino Acid-Based Solutions

Objective

To evaluate the potential clinical role of amino acids as an osmotic agent.

Design

The peritoneal transport of fluid, amino acids, and other solutes was investigated during a 6–hour single-cycle peritoneal dialysis with PDA 1% versus 1.36% glucose (n=6) or PDA 2.7% versus 3.86% glucose solution (n=9).

Patients

Fifteen stable nondiabetic continuous ambulatory peritoneal dialysis (CAPD) patients.

Results

The fractional absorption of the osmotic agents at 6 hours was higher with PDA 2.7% versus glucose 3.86% (p<0.005). The diffusive mass transport coefficient, KeD’ calculated for a period of dialysate isovolemia was higher with PDA 2.7% versus PDA 1% for essential, nonessential (p<0.005), and total (p<0.05) amino acids. The intraperitoneal volume-over-time curves and KqD values for urea, creatinine, glucose, albumin, β2microglobulin, and total protein did not differ between the amino acid solutions and the corresponding glucose solutions. KeD for urea was significantly higher during the dwell with PDA 2.7% versus PDA 1% (p<0.05). Plasma amino acid concentrations increased substantially during the first 1– 2 hours and then decreased gradually. Valine and methionine rose to 792% and 1119% of baseline values, respectively.

Conclusions

We conclude that the peritoneal transport of fluid and investigated solutes, except amino acids, was not different with the amino acid solutions compared with the corresponding equimolar glucose solutions. However, ultrafiltration tended to be lower with amino acid solutions.

Furthermore, the fractional absorption of amino acids and KeD values for amino acids was higher with PDA 2.7% versus PDA 1 %, suggesting an effect of the hypertonic amino acid solution on the peritoneal membrane transport properties. Also, the hypertonic PDA2.7% solution yielded nonphysiologically high plasma levels of several amino acids. We therefore consider this solution not to be safe enough for long term clinical use.”