Curtis R White

US Patent:

50039857, Apr 2, 1991

Filed:

Oct 19, 1989

Appl. No.:

7/423643

Inventors:

Curtis D. White - San Antonio TX
Billy L. Carpenter - San Antonio TX

Assignee:

Nippon Colin Co., Ltd.

International Classification:

A61B 508

US Classification:

128716

Abstract:

A method and apparatus for determining a number of important physiologic characteristics of a patient based on a end tidal determinations taken from a single respiratory waveform. In the preferred embodiment, breath detection, end-tidal occurrence, and respiratory information is determined using only the expired CO. sub. 2 gas concentration waveform. The system of the present invention is capable of performing the following basic functions: (1) identification of breath-by-breath inspired/expired end-tidal gas concentrations of three or more other expired gases (i. e. , O. sub. 2, NO. sub. 2, and a volatile anesthetic); (2) calculation of the respiratory, inspiratory, and expiratory periods; (3) calculation of the respiratory rate and inspiratory/expiratory ratio; and (4) calculation of the multi-breath and time-trend averages. The preferred embodiment of the invention system comprises a breath detection algorithm which is implemented in two phases--initialization and normal. The initialization phase tests for presence of a respiratory signal presence then determines the parameters necessary for the normal search phase.