Pulse oximeter

United States Patent m

Hausman et al.

[li] Patent Number: [45] Date of Patent:

4,883,353 Nov. 28, 1989

[54] PULSE OXIMETER

[75] Inventors: Kenneth A. Hausman, Concord;

Edwin B. Merrick, Stow, both of
Mass.

[73] Assignee: Puritan-Bennett Corporation,

Wilmington, Mass.

[21] Appl. No.: 154,929

[22] Filed: Feb. 11,1988

[51] Int CI* G01N 33/49

[52] U.S. CI 356/41; 128/633

[58] Field of Search 356/39, 40, 41;

128/633

[56] References Cited

U.S. PATENT DOCUMENTS 3,412,729 11/1968 Smith, Jr 128/633

4,167,331 9/1979 Nielsen 356/41 X

4,407,290 10/1983 Wilber et al 356/41 X

4,714,341 12/1987 Hamaguri et al 356/41

Primary Examiner—Vincent P. McGraw
Attorney, Agent, or Firm—Fish & Richardson

[57] ABSTRACT

A pulse oximeter having a sensor responsive to light transmitted through an area of blood flow which is optically absorbed by hemoglobin for producing a pulsatile waveform indicating the current pulsatile component of blood flow. A process waveform is created for tracking the process of the oximeter during its determination of a maximum and a minimum value of the pulsatile waveform, which is used for calculating the saturation of oxygen.

22 Claims, 6 Drawing Sheets