[Continuous veno-venous hemofiltration in treatment of acute severe hyponatremia: a report of 6 cases].

Objective: To investigate the effect of continuous veno-venous hemofiltration (CVVH) in the treatment of acute severe hyponatremia.
Methods: Six patients with acute severe hyponatremia were studied, including 5 males and 1 female, aged 48.5 (25 - 61) years. Clinical manifestations of hyponatremia included confusion (6/6), drowsiness (3/6), and delirium (3/6). The course of hyponatremia before the initiation of CVVH was 45 - 48 hours. AN69, AV600, FH66 and HF1200 hemofilters were applied and changed every 24 hours. The ultrafiltration rate was 2 000 ml/h, with a blood flow rate of 200 - 250 ml/min, and the substitute fluid was infused by a pre-dilution route. Low molecular weight heparin was used for anticoagulation.
Results: The average treatment duration of CVVH was 59.7 (45.6 - 86) hours. All the patients survived and tolerated CVVH well. During CVVH, the serum sodium increased significantly from (101.2 +/- 4.2) mmol/L before CVVH, to (115.0 +/- 2.7) mmol/L at the 6th hour of CVVH, (129.2 +/- 4.1) mmol/L at the 24th hour, and (140.3 +/- 1.6) mmol/L at the 48th hour of CVVH; with the correction rate of serum sodium controlled at (2.5 +/- 0.4) mmol.L(-1).h(-1) over the first 24 hours, (1.2 +/- 0.1) mmol.L(-1).h(-1) for the first 48th hour, and the correction rate of (0.82 +/- 0.10) mmol.L(-1).h(-1). The sodium concentrations in the replacement solution were (16.0 +/- 6.0) mmol/L higher than the serum sodium concentration at 0 hour, (11.6 +/- 4.3) mmol/L higher at 4th hour, (5.5 +/- 5.1) mmol/L higher at 24th hour, and (0.75 +/- 0.96) mmol/L higher at 48th hour of CVVH. After CVVH, the serum osmolarity increased significantly, from (216.7 +/- 7.4) mOsm/kgH(2)O pre-CVVH, to (245.0 +/- 5.5) mOsm/kgH(2)O at 6th hour, with a correction rate of (5.16 +/- 0.81) mOsm.kgH(2)O(-1).h(-1); (272.7 +/- 7.1) mOsm/kgH(2)O at 24th hour, with a correction rate of (2.33 +/- 0.28) mOsm.kgH(2)O(-1).h(-1); and (295.0 +/- 4.2) mOsm/kgH(2)O at 48th hour, with a correction rate of (1.63 +/- 0.20) mOsm.kgH(2)O(-1).h(-1). The Glasgow scores and APACHEII scores improved significantly as compared to pretreatment.
Conclusion: CVVH is effective in the treatment of acute severe hyponatremia, and could be considered as a treatment option because of its slow and continuous nature. A low-sodium replacement solution should be prepared to minimize its sodium concentration difference from the serum concentration. We recommend that the serum sodium concentration be corrected at an average rate of (2.50 +/- 0.14) mmol.L(-1).h(-1) at 6 h, (1.2 +/- 0.1) mmol.L(-1).h(-1) at 24 h and (0.82 +/- 0.10) mmol.L(-1).h(-1) at 48 h.