IIIH
US006814073B2
(12) United States Patent ao) Patent No.: us 6,814,073 B2
Wickham (45) Date of Patent: Nov. 9,2004
Page 2
(54) RESPIRATORY APPARATUS WITH IMPROVED FLOW-FLATTENING DETECTION
(75) Inventor: Peter John D. Wickham, Five Dock (AU)
(73) Assignee: ResMed Limited, North Ryde (AU)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 140 days.
(21) Appl. No.: 09/924,325
(22) Filed: Aug. 8, 2001
(65) Prior Publication Data
US 2002/0043264 Al Apr. 18, 2002
Related U.S. Application Data
(60) Provisional application No. 60/228,630, filed on Aug. 29, 2000.
(51) Int. CI.7 A61M 16/00
(52) U.S. CI 128/204.18; 128/204.23
(58) Field of Search 128/204.18, 204.21,
128/204.22, 204.23, 204.26, 205.11
(56) References Cited
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OTHER PUBLICATIONS
Schwartz, A.R., et al., "Effect of positive nasal pressure on upper airway pressure-flow relationships", J. Appl. Physiol., pp. 1626-1634, 1989.
Smith, PL., et al., "Upper airway presssure-flow relationships in obstructive sleep apnea", J. Appl. Physiol., 64(2):789-95, 1988.
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Primary Examiner—Henry Bennett
Assistant Examiner—-Joseph Weiss
(74) Attorney, Agent, or Firm—Gottlieb Rackman & Reisman, PC.
(57) ABSTRACT
In a respiratory apparatus for treatment of sleep apnea and other disorders associated with an obstruction of a patient's airway and which uses an airflow signal, an obstruction index is generated which detects the flattening of the inspiratory portion of the airflow. The obstruction index is used to differentiate normal and obstructed breathing. The obstruction index is based upon different weighting factors applied to sections of the airflow signal thereby improving sensitivity to various types of respiration obstructions.
40 Claims, 9 Drawing Sheets
CHECK FOR
VALID INSPIRATION
CALCULATE MEAN (M) OF FLOW SIGNAL
ASSIGN WEIGHT FACTORS W, and V, to each sample F.
CALCULATE OBSTRUCTION INDEX
