IN-VIVO GAS TRANSFER PERFORMANCE OF THE INTRAVASCULAR OXYGENATOR IN ACUTE RESPIRATORY-FAILURE

The intravascular oxygenator (IVOX) has undergone both animal and clin ical trials. Data from the animal studies have demonstrated that the d evice is capable of transferring up to approximately 100 ml/min of oxy gen and carbon dioxide. Initial data from the human trials suggest tha t gas transfer, although approaching these levels, varied widely in pa tients with respiratory failure. We studied the factors affecting gas exchange in 26 patients with severe acute respiratory failure who unde rwent intravenacaval support of gas exchange with IVOX. The patients u nderwent monitoring of IVOX gas transfer rates, hemodynamics, blood ga ses, and ventilation parameters at scheduled intervals following devic e insertion. All devices functioned following implantation. The mean v alue for O2 transfer was 64 +/- 21 SD ml/min (range 15-114 ml/min) and for CO2 transfer was 48 +/- 17 ml . min-1 (range 14-112 ml/min). CO2 transfer correlated positively with device surface area, cardiac outpu t, and mixed venous Pco2 and negatively with duration of implantation. O2 transfer did not correlate with any patient factors probably due t o error inherent in the measurement of this variable. Independent meas urements of IVOX gas transfer by respiratory gas exchange in a subset of patients with normal values of mixed venous Pco2 were in good agree ment with the routine measurements and indicated that the device provi ded up to 26% of gas exchange requirements in this subset. We conclude that IVOX transfers clinically useful amounts of oxygen and carbon di oxide in vivo. Factors that influence gas transfer include device surf ace area, Pvco2, cardiac output, and duration of implantation. Optimiz ation of these factors (such as with permissive hypercapnea) could res ult in enhanced performance in vivo.