Method and apparatus for providing ventilatory assistance

• US 8,733,351 B2
• Filed: 09/21/2011
• Issued: 05/27/2014
• Est. Priority Date: 09/23/1996
• Status: Expired due to Fees

• Current Assignee: Resmed Limited (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Berthon-Jones, Michael
• Primary Examiner(s): MATTER, KRISTEN CLARETTE
• Application Number:
  US13/238,670
• Publication Number:
  US 20120006328A1
• Time in Patent Office: 979 Days
• Field of Search: 128/200.24, 128/204.18, 128/204.21, 128/204.23, 700/50, 706/1, 706 7- 9
• US Class Current: 128/204.23
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/1055 bacterial
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

The apparatus provides for the determination of the instantaneous phase in the respiratory cycle, subject'"'"'s average respiration rate and the provision of ventilatory assistance. A microprocessor (16) receives an airflow signal from a pressure transducer (18) coupled to a port (17) at a mask (11). The microprocessor (16) controls a servo (19), that in turn controls the fan motor (20) and thus the pressure of air delivered by the blower (10). The blower (10) is coupled to a subject'"'"'s mask (ii) by a conduit (12). The invention seeks to address the following goals: while the subject is awake and making substantial efforts the delivered assistance should be closely matched in phase with the subject'"'"'s efforts; the machine should automatically adjust the degree of assistance to maintain at least a specified minimum ventilation without relying on the integrity of the subject'"'"'s chemoreflexes; and it should continue to work correctly in the presence of large leaks.

Claims

1. A method for providing ventilatory assistance to a patient using a processor-controlled ventilation delivery device comprising the steps of:

delivering ventilatory assistance to a patient according to a waveform template,

determining the instantaneous respiratory phase of the patient'"'"'s respiratory cycle,

determining an estimate of the patient'"'"'s airflow throughout the patient'"'"'s respiratory cycle,

calculating at least one fuzzy index indicative of any leak change throughout the patient'"'"'s respiratory cycle,

calculating an instantaneous inspired volume as a function of said estimate of the patient'"'"'s respiratory airflow and a weighted coefficient based on the at least one fuzzy index, and

delivering ventilation to the patient according to the determined respiratory phase and the calculated inspired volume.

2. The method of claim 1 wherein said fuzzy index is calculated as the fuzzy extent to which the estimate of respiratory airflow is large for longer than expected.

3. An apparatus for providing ventilatory assistance to a patient comprising:

a blower for delivering ventilation to a patient;

a patient interface in communication with said blower; and

a processor for controlling said blower;

wherein said processor determines the instantaneous phase of the patient'"'"'s respiratory cycle, determines an estimate of the patient'"'"'s airflow throughout the cycle, calculates the inspired volume as a function of said respiratory airflow, calculates at least one fuzzy index indicative of any leak change throughout the patient'"'"'s respiratory cycle, calculates an instantaneous inspired volume as a function of said estimate of the patient'"'"'s respiratory airflow and a weighted coefficient based on the at least one fuzzy index, and controls the blower by delivering ventilation according to the determined respiratory phase and the calculated inspired volume.

4. The apparatus of claim 3

wherein said fuzzy index is calculated as the fuzzy extent to which the estimate of respiratory airflow is large for longer than expected.