Patent ID: 6308706
Filing Date: 2001-10-30
Classification: A61B,A61M

Abstract:
A ventilation system comprising(a) a ventilation tube system comprising a treatment device for creating a first flow resistance and a device selected from the group consisting of a filter and a heat and moisture exchanger;(b) a monitoring unit for evaluating ventilation system quantities selected from the group consisting of pressure quantities and flow quantities;(c) first and second pressure sensors located respectively upstream and downstream of the treatment device;(d) means for creating a second flow resistance in series to the first flow resistance, said second flow resistance being suitable as a reference;(e) third and fourth pressure sensors located respectively upstream and downstream of the means for creating a second flow resistance;(f) whereby said pressure sensors feed signals to the monitoring unit, the monitoring unit calculating selected parameters derived from a first differential pressure across the first flow resistance and a second differential pressure across the second flow resistance as a function of time to determine the degree of permeability of the filter or exchanger.