RESUMO
This study was designed to assess lactate and TCO2 transfers during PET and in 24-hour drained dialysate, relating them with the membrane transport type and acid-base status. Forty PETs were studied, performed in 23 clinically stable patients maintained on CAPD for 6.5 +/- 3 months using 35 mEq/l of lactated-based dialysate. No significant changes in plasma concentration of lactate and TCO2 were observed. Lactate gain (LG) was 51.91 +/- 4.86 and 220.82 +/- 22.61 mEq and TCO2 loss was 46.49 +/- 6.9 and 183.51 +/- 32.9 mEq during PET and 24 h respectively. When analyzed these transfers according to membrane transport characteristics (High/High-average group: HHAG and low/low-average group: LLAG), LG was significantly higher (53.94 +/- 3.7 vs 48.86 +/- 4.8 mEq during TEP p < 0.01, and 228.06 +/- 15.6 vs 209.96 +/- 27.2 mEq during 24 h p < 0.05). TCO2 loss was greater (48.66 +/- 7.15 vs 43.25 +/- 5.5 mEq p < 0.05 and 187.22 +/- 27.3 vs 177.93 +/- 35.3 during PET and 24 h respectively) in HHAG vs LLAG. When evaluating transfers according to patients' acid-base status (normal and acidotic group), no significant differences were found in LG, but there was a significant difference in TCO2 loss (47.7 +/- 5.9 vs 39.76 +/- 6.1 mEq p < 0.01). We did not observe significant differences in acid-base balance during PET according to membrane transport characteristics (HHAG vs LLAG). However, acid-base balance was more positive in acidotic patients' PET than in normal patients (9.87 +/- 6.6 vs 3.92 +/- 6.8 mEq p < 0.05). TCO2 loss during PET directly correlated with plasma TCO2 concentration pre-PET (r: 0.43, p < 0.01). However no significant correlation was found between plasma lactate levels and lactate gain during PET. In conclusion, the lactate gain and bicarbonate loss account for the net dialytic base balance during PET and 24 h. However, the peritoneal membrane transport characteristics as well as the acid-base status can determine a higher or lower aionic transfer (lactate and bicarbonate).