Patent ID: 7793659

Claim:
A bymixer device comprising: an inflow port connectable to a conduit such that all respiratory gas flowing through that conduit will enter the inflow port; a flow divider which divides the flow of respiratory gas that enters the inflow port into first and second streams; a main flow channel through which the first stream flows; a bypass flow channel through which the second stream flows; said bypass flow channel comprising a) a flow restrictor that restricts the flow of gas through the bypass flow channel, b) a mixing chamber positioned upstream of the flow restrictor, said mixing chamber comprising tubing that is alternately extendable and contractible so as to enable a user to alternately increase and decrease the volume of the mixing chamber; and c) sampling apparatus for sampling respiratory gas from said mixing chamber; a flow combiner that combines the first and second streams after they have passed through the main flow channel and bypass flow channel to form a combined outflow stream; and an outflow port that is connectable to a conduit such that the combined outflow stream enters that conduit.