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

Abstract

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.