Patent ID: 6277081
Filing Date: 2001-08-21
Classification: G01N

Abstract:
An apparatus for measuring the concentration of anesthetic gas in a patient's respiratory airstream flowing through a gas conduit comprising:a source of infrared radiation for illuminating the gas in the conduit;a plurality of independent infrared detectors for detecting infrared radiation from the gas illuminated in the conduit, each detector further comprising a filter to permit only infrared radiation of a particular wavelength to reach each respective infrared detector;one or more reference infrared detectors, each detector furtherer comprising a filter to permit only infrared radiation of a particular wavelength to reach each respective reference infrared detector;at least one blocked infrared detector with an opaque filter to prevent substantially all infrared radiation from reaching said blocked detector infrared detector, the number of blocked infrared detectors being fewer than said plurality of independent infrared detectors; anda processor for correcting each independent infrared detector output by algebraic removal of a scaled version of the output of said reference and said at least one blocked infrared detectors from the output of each independent infrared detector.