Arteriovenous perfusion with a disposable bubble oxygenator for the temporary support of respiration

Prolonged pumpless arteriovenous perfusion for carbon dioxide extraction

A method of extracorporeal carbon dioxide extraction from the blood using an efficient microporous membrane oxygenator or membrane gas exchanger was evaluated during pumpless arteriovenous perfusions with a view to its application for partial respiratory support. The first study carried out in dogs revealed some increase in cardiac output, cardiac index, and cardiac work, although this increase was less than that normally expected from the added extracorporeal blood flow. In sheep during 3 to 7 days of continuous bypass, there was practically no hemolysis and relatively stable hemoglobin and hematocrit levels, and the platelet counts remained within safe levels. The maximum extracorporeal blood flow tended to decrease from a mean of 1.55 L/min on day 1 to 1.34 L/min on day 3 to 1.28 L/min on day 7. Carbon dioxide extraction remained efficient throughout the perfusion, but there was a minimal decrease from the first day (10.92 mmol/L) to the third day (8.46 mmol/L) at the higher blood carbon dioxide concentrations; it remained stable thereafter at 9.0 mmol/L.

Cardiopulmonary Dynamics during Pumpless Arteriovenous Bypass for Respiratory Assistance

The effect of a pumpless arteriovenous bypass with a microporous membrane oxygenator (MO) on the cardiopulmonary dynamics of dogs revealed an increase in cardiac output and cardiac work proportional to the increase in extracorporeal blood flow. Several current MOs offer so little resistance to blood flow that shunt flows exceeding a third of the normal cardiac output can easily be obtained. This should be enough for CO2 extraction covering metabolic production, and would add a non negligible amount of O2 to the blood