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Adult ECMO Simulator

The effect of 'Sweep' Gas Flow Rate on PaCO2.

The data shown below are from a simulated patient with severe respiratory failure and an oxygen consumption of ~200 ml/min on stable VV ECMO. The patient has been completely paralysed with pancuronium and is ventilated on 100% oxygen with a tidal volume of 400 mls at 10 breaths per minute. The VV ECMO system has been set at a constant blood flow rate of 5.0 lpm while the ‘Sweep Gas’ rate has been increased step-wise from 2.0 lpm to 10 lpm. The patient's native cardiac output is about 5 lpm.

Note how the PaCO2 falls steadily from about 60 mm Hg at a sweep gas rate of 2 lpm to about 27 mm Hg at a sweep gas rate of 10 lpm.

Thus we can appreciate one of the important concepts of VV ECMO – that, for any given blood flow, carbon dioxide clearance is largely determined by the rate of gas flow through the oxygenator.

Effect Of Fresh Gas Flow