The impact of peritonitis on peritoneal and systemic acid-base status of patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE

To assess the possible effects of peritonitis on peritoneal and systemic acid-base status.

DESIGN

pH, pCO2, lactate, and total leukocyte and differential count were simultaneously determined in the overnight dwell peritoneal dialysis effluent (PDE) and arterial blood in noninfected patients (controls) and on days 1, 3, and 5 from the onset of peritonitis.

SETTING

University multidisciplinary dialysis program.

PATIENTS

Prospective analysis of 63 peritonitis episodes occurring in 30 adult CAPD patients in a single center.

RESULTS

In controls, mean (+/- SD) acid-base parameters were pH 7.41 +/- 0.05, pCO2 43.5 +/- 2.6 mm Hg, lactate 2.5 +/- 1.5 mmol/L in the PDE, and pH 7.43 +/- 0.04, PaCO2 36.8 +/- 3.8 mm Hg, lactate 1.4 +/- 0.7 mmol/L in the blood. In sterile (n = 6), gram-positive (n = 34), and Staphylococcus aureus (n = 9) peritonitis PDE pH's on day 1 were, respectively, 7.29 +/- 0.07, 7.32 +/- 0.07, and 7.30 +/- 0.08 (p < 0.05 vs control). In gram-negative peritonitis (n = 14) PDE pH was 7.21 +/- 0.08 (p < 0.05 vs all other groups). A two-to-threefold increase in PDE lactate was observed in all peritonitis groups, but a rise in pCO2 was only seen in gram-negative peritonitis. Acid-base profile of PDE had returned to control values by day 3 in sterile, gram-positive and Staphylococcus aureus peritonitis and by day 5 in gram-negative peritonitis. Despite a slight increase in plasma lactate on the first day of peritonitis, arterial blood pH was not affected by peritonitis.

CONCLUSION

PDE pH is decreased in continuous ambulatory peritoneal dialysis (CAPD) peritonitis, even in the absence of bacterial growth. In gram-negative peritonitis, PDE acidosis is more pronounced and prolonged, and pCO2 is markedly increased. Arterial blood pH is not affected by peritonitis.