Successful VV-ECMO weaning facilitated by addition of sodium bicarbonate to the dialysate in a COVID-19 patient with severe metabolic acidosis

Abstract

Case: A man in his 60s with COVID-19 required mechanical ventilation on day 8 of the illness. On day 12, the P/F ratio reached 120, and veno-venous ECMO （VV-ECMO） was started. His creatinine level increased to 1.45 mg/dL, and high-volume continuous hemofiltration was initiated. On day 19, he developed severe diarrhea, with losses exceeding 2,000 g/day, and metabolic acidosis (pH 7.19). The renal failure worsened (creatinine 1.78 mg/dL). It was difficult to maintain pH when PaCO₂ exceeded 50 mmHg. NaHCO₃ (bicarbonate 35 mEq/L) was added to the replenisher to raise the bicarbonate level to 40 mEq/L, and continuous renal replacement therapy was initiated. The bicarbonate level increased to 27 mEq/L and pH improved to 7.34. However, NaHCO₃ supplementation was discontinued owing to an increased serum sodium level, and metabolic acidosis worsened. Therefore, the same dosage was reinitiated to maintain the pH, and weaning from VV-ECMO was started. VV-ECMO was stopped on day 41. Conclusion: Addition of NaHCO₃ to the dialysate to facilitate prolonged VV-ECMO withdrawal in severe metabolic acidosis can be performed safely. It does not require intravenous access and the risk of infection is lower than with conventional intravenous infusion.