Apparatus for aspirating a dead space

Abstract

In a method and apparatus for determining an aspiration flow and an aspiration time during aspiration of a dead space, the aspiration is made more effective by determining the volume of the dead space to be aspired during an expiration, determining an expiration flow with respect to time during at least a latter part of the expiration, and optimizing the aspiration time and the aspiration flow from the determined volume of the dead space and the measured expiration flow with respect to time is such a way that the dead space can be aspirated during an ongoing expiration with a minimum of interference to the flow balance in the expiration flow as observed from a point upstream and/or downstream the dead space.

1 . An apparatus for aspiration of gas from a dead space associated with breathing assistance involving a breathing cycle having an expiration phase and an inhalation phase, said apparatus comprising: 
 aspiration tubing in fluid communication with a dead space;    an extraction unit in fluid communication with said aspiration tubing; and    a regulating unit comprising a first signal input at which an expiration flow signal is received, representing a determined expiration flow with respect to time, and a second signal input at which a dead space signal is received, representing the dead space to be aspirated during the expiration phase, said regulating unit optimizing an aspiration time and an aspiration flow of said aspiration to allow the dead space to be aspirated during an ongoing expiration with a minimum of interference with a flow balance in the expiration flow at a point selected from the group consisting of a point upstream of said dead space, and a point downstream of said dead space, said regulating unit operating said extraction unit to generate said aspiration flow during said aspiration time.