Low-dose citrate continuous veno-venous hemofiltration (CVVH) and acid-base balance

T. Naka, M. Egi, Rinaldo Bellomo, L. Cole, C. French, L. Wan, N. Fealy, I. Baldwin

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Abstract

Objective: To evaluate the acid-base effect of low-dose regional citrate anticoagulation (RCA) during continuous veno-venous hemofiltration (CVVH). Design: Prospective observational study. Setting: ICUs of tertiary public and private hospitals. Subjects: Thirty critically ill patients with acute renal failure at risk of bleeding or with a major contraindication to heparin-CVVH and/or short filter life. Methods: We used a commercial citrate-based fluid (11 mmol/L, sodium: 140 mmol/L, chloride: 108 mmol/L and 1 mol/L of potassium) as pre-dilution replacement fluid during CVVH. Further potassium was added according to serum potassium levels. We measured all relevant variables for acid-base analysis according to the Stewart-Figge methodology. Results: Before treatment, study patients had a slight metabolic acidosis, which worsened over 6 hours of RCA-CVVH (pH from 7.39 to 7.38, p<0.005; bicarbonate from 23.2 to 21.6 mmol/L, p<0.0001 and base excess from -2.0 to -3.0 mEq/L, p<0.0001) due to a significant increase in SIG (from 5.8 to 6.6 mEq/L, p<0.05) and a decrease in SIDa (from 37.5 to 36.6 mEq/L, p<0.05). These acidifying effects were attenuated by hypoalbuminemia and a decrease in lactate (from 1.48 to 1.34 mmol/L, p<0.005) and did not lead to progressive acidosis. On cessation of treatment, this acidifying effect rapidly self-corrected within six hours. Conclusions: Low dose RCA-CVVH induces a mild acidosis secondary to an increased strong ion gap and decreased SIDa which fully self-corrects at cessation of therapy. Clinicians need to be aware of these effects to correctly interpret changes in acid-base status in such patients.

Original languageEnglish
Pages (from-to)222-228
Number of pages7
JournalInternational Journal of Artificial Organs
Volume28
Issue number3
Publication statusPublished - 1 Mar 2005
Externally publishedYes

Keywords

  • Acid-base balance
  • Acidosis
  • Acute renal failure
  • Anticoagulation
  • Citrate
  • Lactate strong ion difference
  • Stewart

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