Low-dose citrate continuous veno-venous hemofiltration (CVVH) and acid-base balance.
OBJECTIVE
To evaluate the acid-base effect of low-dose regional citrate anticoagulation (RCA) during continuous veno-venous hemofiltration (CVVH).


METHODS
Prospective observational study.


METHODS
ICUs of tertiary public and private hospitals.


METHODS
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.
Naka
T
T
Department of Intensive Care and Department of Medicine, Austin Hospital and Melbourne University, Melbourne, Australia.
Egi
M
M
Bellomo
R
R
Cole
L
L
French
C
C
Wan
L
L
Fealy
N
N
Baldwin
I
I
D000136:Acid-Base Equilibrium / Q000502:physiology*; D058186:Acute Kidney Injury / Q000628:therapy*; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D019343:Citric Acid / Q000627:therapeutic use*; D015331:Cohort Studies; D016638:Critical Illness; D005260:Female; D006440:Hemofiltration / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
D000925:Anticoagulants; D019343:Citric Acid