A new type of low blood flow ECCO₂R using a hemodialysis system in apneic states

Abstract

To perform low blood flow extracorporeal CO₂ removal (ECCO₂R), we developed a device for extracorporeal circulation (ECC) equipped with a dialyzer for elimination of CO₂ as bicarbonate. The major problem with this method was the decrease in blood pH. To control blood pH and clarify the limit of CO₂ elimination in this method, a study of apneic dogs was performed. Six anesthetized mongrel dogs were intubated and paralyzed with muscle relaxant. Vascular access was achieved with venovenous bypass. ECC was initiated under apneic oxygenation (100% O₂, 10 cm H₂O continuous airway pressure), and the CO₂ concentration in the airway outlet was measured.
The CO₂ was converted to bicarbonate by systemic infusion of trihydroxymethylamino methane (THAM), and generated bicarbonate was removed by hemodialysis. Blood flow rate in the ECC wan 15 ml/kg/min, and the duration of ECC was 5 hr. During ECC, the hemodynamic parameters of the dogs were stable, and the PaCO₂ remained at about 90 mmHg with a PaO₂ above 350 mmHg ; CO₂ elimination from the airway was negligible.