CHARACTERISATION OF MASK SYSTEMS

• US 20120090610A1
• Filed: 09/27/2011
• Published: 04/19/2012
• Est. Priority Date: 12/29/2000
• Status: Active Grant

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: O'Connor, Gerard Michael, Oates, John David, Wickham, Peter John Deacon, Wickham, Nicola Frances
• Granted Patent: US 8,677,997 B2
• Time in Patent Office: Days
• US Class Current: 128/204.21
• 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 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• 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 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 16/1055 bacterial
• CPC Class Codes: A61M 16/106 in a 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 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 2230/46 Resistance or compliance of the lungs

Abstract

A method and CPAP apparatus characterizes different mask systems, e.g., masks and hoses. The CPAP apparatus can be calibrated for different mask systems and hoses by including sensors that measure flow and pressure at a flow generator of the apparatus. When the generator is fitted to a new mask system, or any changes are made to an existing one, a method calibrates the generator for the mask system. The method includes determining air flow characteristics using flow measurements from a first test period when flow through the mask system is open, measuring or estimating pressure in the mask system during a second test period when flow through the mask system is blocked and determining air flow characteristics of the diffuser of the mask system using the air flow characteristics of the air delivery hose determined during the first period and the pressure measurements made during the second period.

Claims

1-38. -38. (canceled)

39. A method for determining a characteristic of a mask system connected to a ventilation delivery device for delivering breathable air to a patient, where said ventilation delivery device includes a processor-controlled blower, a pressure sensor, and a flow sensor;

and said mask system includes a patient interface with a diffuser and an air delivery hose, the method comprising the steps of;

delivering breathable air at a first flow rate and measuring a corresponding first pressure drop in the air delivery hose,

delivering breathable air at a second flow rate and measuring a corresponding second pressure drop in the air delivery hose,

blocking the patient interface,

applying a first test pressure to the diffuser, minimizing unintentional leak and measuring a first diffuser flow corresponding to the first test pressure,

applying a second test pressure to the diffuser and measuring a corresponding second diffuser flow, and

determining a characteristic of the mask system as a function of the first and the second flow rates and their corresponding measured pressure drops, and the first and the second test pressures and their corresponding measured diffuser flows.

40. The method of claim 39 wherein the function includes a quadratic.

41. The method of claim 39 wherein the function includes a quadratic.

42. The method of claim 39 wherein the characteristic is flow.

43. The method of claim 39 wherein the characteristic is patient interface pressure.

44. The method of claim 39 wherein the characteristic is pressure drop in the hose.

45. The method of claim 39 wherein the characteristic is diffuser flow.

46. An apparatus for determining a characteristic of a mask system, which includes an air deliver hose and patient interface with a diffuser, connected to a ventilation delivery system including

a processor-controlled blower,

a pressure sensor, and

a flow sensor,

wherein said blower delivers flow at a first constant flow rate, said pressure sensor senses pressure drop in the air delivery hose,

said blower subsequently delivers flow at a second constant flow rate and said pressure sensor senses pressure drop in the air delivery hose,

said patient interface is blocked and said processor separately applies at least two test pressures to the diffuser and said flow sensor senses corresponding diffuser flows, and

said processor determines a characteristic of the mask system as a function of the first and the second flow rates and their corresponding measured pressure drops, and the first and the second test pressures and their corresponding measured diffuser flows.

47. The apparatus of claim 46 wherein the function includes a quadratic.

48. The apparatus of claim 46 wherein the function includes a quadratic.

49. The apparatus of claim 46 wherein the characteristic is flow.

50. The apparatus of claim 46 wherein the characteristic is patient interface pressure.

51. The apparatus of claim 46 wherein the characteristic is pressure drop in the hose.

52. The apparatus of claim 46 wherein the characteristic is diffuser flow.