Sidestream gas sampling system with detachable sample cell

#for monitoring respiratory gases such as a radiation source and detector, are coupled to the sample cell to measure the constituents of gas passing through the sample cell. An example of such a conventional mainstream Gas Measurement System is shown in U.S. Pat. No. 4,914,720 issued to Knodle et al.

#A sidestream type of gas sampling system transports a portion of sampled gases from the sampling site, which is typically a breathing circuit coupled to the patient's airway or directly at the patient's airway, through a sampling tube to the sample cell, where the constituents of the gas are measured by a gas sensing system. Gases are continuously aspirated from the sample site, through the sampling tube, and into the sample cell, which is located within a gas measurement instrument. Gases are commonly sampled at flow rates ranging from about 50 ml/min to about 250 ml/min.

#The optical and electronic components associated with the sample cell for measuring the gas passing therethrough are positioned in the monitor a distance away from the patient's airway or a respiratory circuit. Examples of conventional sidestream gas sampling systems are taught in U.S. Pat. Nos. 4,692,621 to Passaro et al.; 4,177,381 to McClatchie; 5,282,473 to Braig et al.; and 5,932,877 also issued to Braig et al.

#FIG. 1A is a top view of a first embodiment of a stand-alone sidestream gas sampling system according to the principles of the present invention, and FIG. 1B is an exploded view of the sidestream gas measurement assembly in the sidestream gas sampling system shown in FIG. 1A;

#FIGS. 2A-2B are, respectively, perspective and exploded views of a second embodiment of a sidestream gas sampling system that forms a component in a multiparameter monitoring apparatus according to the principles of the present invention;

#FIGS. 3A and 3B are perspective views and FIG. 3C is an exploded view of third embodiment of a sidestream gas measurement assembly of a sidestream gas sampling system that is adapted to be tightly coupled to a multi-parameter monitoring system;

#FIGS. 1A and 1B illustrate a first embodiment of a stand-alone sidestream gas sampling system 30 according to the principles of the present invention. Sidestream gas sampling system 30 includes a sidestream gas measurement assembly 40 and a sample cell 60 that selectively attaches to the sidestream gas measurement assembly. Sidestream gas measurement assembly 40 is shown in exploded view in FIG. 1B.

#Sidestream gas measurement assembly 40 includes a housing 42, which, in an exemplary embodiment of the present invention, is defined by two housing portions 42a and 42b that are adapted to be joined together in an assembled relation. The various elements of sidestream gas measurement assembly 40 may be at least partially contained within or otherwise carried by housing 42, which is configured to receive a substrate 43 on which one or more of the components of the sidestream gas measurement assembly can be mounted. A radiation source 44 and a radiation detector 46 are disposed in the housing in optical alignment so that radiation emitted by the source is received by the detector after passing through the gas contained in sample cell 60.

#In an exemplary embodiment of the present invention, radiation source 44 includes an infrared emitter, a mounting, a parabolic mirror, and a window of an infrared radiation-transmitting material, such as sapphire. Radiation detector 46 comprises a window of infrared radiation-transmitting material, a beam splitter, one or more filters, and data and reference detectors. Radiation detector 46 may also include electronics that facilitate monitoring and/or temperature control of the data and reference detectors thereof.