Extracorporeal CO2 removal in a lung lavage model of respiratory failure

Extracorporeal life support (ECLS) is a recognized treatment for neonatal respiratory distress unresponsive to other forms of therapy. Variations of this technique are being developed in an effort to extend its applicability and safety. Extracorporeal CO2 removal (ECCO2R) is one such modification that requires blood flows of 20% to 50% of cardiac output and therefore lends itself to percutaneous venous cannulation. The authors evaluated ECCO2R in conjunction with low-frequency ventilation, using a lung lavage-induced model of respiratory failure in rabbits. Six rabbits were lavaged an average of 9 times with 15 mL/kg Plasma-Lyte A at 37 degrees C via an endotracheal tube. Incremental ventilatory changes were made during lavage, to an FIO2 of 1.0, rate of 80, peak inspiratory pressure (PIP) of 37 cm H2O, and positive end-expiratory pressure (PEEP) of 4 cm H2O. Arterial blood gas values of PaO2 < 40 mm Hg and PaCO2 > 60 mm Hg resulted, meeting our criteria for respiratory failure. The rabbits were placed on veno-venous ECCO2R using a 0.8-m2 hollow fiber oxygenator and a commercially available double-lumen dialysis catheter. Blood flows of 10 to 20 mL/kg/min were used to manage CO2 removal. A low-frequency ventilation technique was employed using an FIO2 of 1.0 and a rate of 5 breaths per minute. PEEP was increased incrementally to maintain the PaO2 above 80 mm Hg. After initiation of ECCO2R, the arterial PaO2 increased to 165 +/- 109 mm Hg, with PEEP above 15 cm H2O, and PaCO2 decreased to 37 +/- 5 mm Hg, with a bypass flow rate of 15 mL/kg/min.(ABSTRACT TRUNCATED AT 250 WORDS)