US-20260124412-A1 - FLOW PATH FAULT DETECTION METHOD FOR A RESPIRATORY ASSISTANCE APPARATUS

US20260124412A1US 20260124412 A1US20260124412 A1US 20260124412A1US-20260124412-A1

Abstract

A respiratory assistance apparatus is configured to provide a heated and humidified glow of gases and has a control system that is configured to detect a fault in the flow path. A flow path is provided for a gases stream through the apparatus from a gas inlet through a blower unit and humidification unit to a gases outlet. A flow rate sensor is provided in the flow path and is configured to sense the flow rate and generate an flow rate signal and/or a motor speed sensor is provided that is configured to sense the motor speed of the blower unit and generate an indicative motor speed signal.

Inventors

Kevin Peter O'Donnell
John Han
Jack Che-Wei Hsu
Samuel Robertson Frame
Grant Martin Dover

Assignees

FISHER & PAYKEL HEALTHCARE LIMITED

Dates

Publication Date: 20260507
Application Date: 20250812

Claims (20)

1 . (canceled)
2 . A respiratory assistance system which detects a blockage in a flow path, the respiratory assistance system comprising: a motor-driven blower unit which generates a gases stream at a configurable set flow rate into the flow path; a humidification unit comprising a removable humidification chamber which heats and humidifies the flow of gases in the flow path and which is fluidly connected or coupled to the motor-driven blower unit; and a controller which: controls a motor speed of the blower unit to deliver the gases stream at the set flow rate in normal operation; detects, in a first stage operating at a first motor speed or first set flow rate, a possible blockage based on comparing a sensed or determined motor speed or flow rate against a first blockage threshold that is based on a flow rate versus motor speed characteristic; increases the first motor speed or first set flow rate to a higher motor speed or higher set flow rate if an indicative blockage is detected in the first stage; detects, in a second stage operating at the higher motor speed or the higher set flow rate, a blockage based on comparing a sensed or determined motor speed or flow rate against a second blockage threshold that is based on a flow rate versus motor speed characteristic; and generates a blockage detection signal if a blockage is detected in the second stage.
3 . The respiratory assistance system of claim 2 wherein the blockage detected in the second stage is indicative of a true blockage, following the detection of the possible blockage in the first stage.
4 . The respiratory assistance system of claim 2 , further comprising a patient interface in the flow path comprising a flexible user conduit connected to a gases outlet of the system at one end and a user interface at another end, and wherein the first and second blockage thresholds are configured for detecting a blockage in the flow path extending from an outlet of the blower unit to the user interface.
5 . The respiratory assistance system of claim 2 , wherein the second blockage threshold of the second stage is set based on a true or expected flow rate versus motor speed characteristic for a flow path having a blockage.
6 . The respiratory assistance system of claim 2 , wherein the second stage of detecting comprises detecting true blockages based on filtering out possible blockages detected in the first stage that are false alarms.
7 . The respiratory assistance system of claim 2 , further comprising adjusting the first blockage threshold if a blockage is not detected in the second stage.
8 . The respiratory assistance system of claim 7 , wherein adjusting the first blockage threshold comprises adjusting the first blockage threshold by a predetermined level or limiting the adjustment of the first blockage threshold based on a stored limit level.
9 . The respiratory assistance system of claim 7 , wherein the first blockage threshold is adjusted multiple times as blockage detection is repeated or looped during operation of the system such that the first blockage threshold is progressively modified to a value having a reduced probability of false alarms relative to its original value.
10 . The respiratory assistance system of claim 2 , wherein the first motor speed or first set flow rate of the first stage is a current motor speed or set flow rate in normal operation, such that the first stage is during normal operation.
11 . The respiratory assistance system of claim 2 , wherein if no blockage is detected at the second stage, the controller reduces the motor speed or set flow rate to that of a prior normal operation or to the first motor speed or first set flow rate.
12 . The respiratory assistance system of claim 2 , wherein increasing the first motor speed or first set flow rate to the higher motor speed or the higher set flow rate comprises increasing the motor speed or set flow rate by or to a predetermined higher value or into a predetermined higher range.
13 . The respiratory assistance system of claim 2 , wherein the controller further triggers an alarm or warning if the blockage detection signal is generated.
14 . The respiratory assistance system of claim 2 , wherein the controller further shuts down the blower unit if the blockage detection signal is generated.
15 . The respiratory assistance system of claim 2 , wherein the controller further enters a standby mode if the blockage detection signal is generated.
16 . The respiratory assistance system of claim 2 , wherein the controller reruns the blockage detection continuously or periodically.
17 . The respiratory assistance system according to claim 2 , further comprising a flow rate sensor in the flow path which senses the flow rate.
18 . The respiratory assistance system of claim 2 , further comprising a motor speed sensor which senses the motor speed of the blower unit or wherein the motor speed is sensed by the controller.
19 . The respiratory assistance system of claim 2 , further comprising: a gases inlet configured to receive a supply of gases; a gases outlet for the heated and humidified gases stream; a flow path for the gases stream through the system from the gas inlet through the blower unit and humidification unit to the gases outlet; and a flow rate sensor in the flow path that is configured to sense the flow rate and generate an indicative flow rate signal or a motor speed sensor that is configured to sense the motor speed of the blower unit and generate an indicative motor speed signal.
20 . A method for detecting a blockage in a flow path of a respiratory assistance apparatus, the flow path comprising a motor-driven blower unit that is configured to generate a gases stream at a configurable set flow rate and which is fluidly connected or coupled to a humidification unit comprising a removable humidification chamber that is configured to heat and humidify the flow of gases, comprising: controlling a motor speed of the blower unit to deliver the gases stream at the set flow rate in normal operation; detecting, in a first stage operating at a first motor speed or first set flow rate, a possible blockage based on comparing a sensed or determined motor speed or flow rate against a first blockage threshold that is based on a flow rate versus motor speed characteristic; increasing the first motor speed or first set flow rate to a higher motor speed or higher set flow rate if an indicative blockage is detected in the first stage; detecting, in a second stage operating at the higher motor speed or the higher set flow rate, a blockage based on comparing a sensed or determined motor speed or flow rate against a second blockage threshold that is based on a flow rate versus motor speed characteristic; and generating a blockage detection signal if a blockage is detected in the second stage.

Description

FIELD OF THE INVENTION This invention relates to a flow path fault detection method and system for a respiratory assistance apparatus that provides a stream of heated and humidified gases to a user for therapeutic purposes. In particular, although not exclusively, the respiratory assistance apparatus may provide respiratory assistance to patients or users who require a supply of heated and humidified gases for respiratory therapies such as respiratory humidification therapy, high-flow oxygen therapy, Positive Airway Pressure (PAP) therapies, including CPAP therapy, Bi-PAP therapy, and OPAP therapy, and typically for the treatment of diseases such as Obstructive Sleep Apnea (OSA), snoring, or Chronic Obstructive Pulmonary Disease (COPD). BACKGROUND TO THE INVENTION Respiratory assistance devices or systems for providing a flow of humidified and heated gases to a patient for therapeutic purposes are well known in the art. Systems for providing therapy of this type (for example respiratory humidification) typically have a structure where gases are delivered to a humidifier chamber from a gases source, such as a blower (also known as a compressor, an assisted breathing unit, a fan unit, a flow generator or a pressure generator). As the gases pass over the hot water, or through the heated and humidified air in the humidifier chamber, they become saturated with water vapour. The heated and humidified gases are then delivered to a user or patient downstream from the humidifier chamber, via a gases conduit and a user interface. In one form, such respiratory assistance systems can be modular systems that comprise a humidifier unit and a blower unit that are separate (modular) items. The modules are connected in series via connection conduits to allow gases to pass from the blower unit to the humidifier unit. For example, FIG. 1 shows a schematic view of a user 1 receiving a stream of heated and humidified air from a modular respiratory assistance system. Pressurised air is provided from an assisted breathing unit or blower unit 2a via a connector conduit 10 to a humidifier chamber 4a. The stream of humidified, heated and pressurised air exits the humidification chamber 4a via a user conduit 3, and is provided to the patient or user 1 via a user interface 5. In an alternative form, the respiratory assistance systems can be integrated systems in which the blower unit and the humidifier unit are contained within the same housing. A typical integrated system consists of a main blower unit or assisted breathing unit which provides a pressurised gases flow, and a humidifier unit that mates with or is otherwise rigidly connected to the blower unit. For example, the humidifier unit is mated to the blower unit by slide-on or push connection, which ensures that the humidifier unit is rigidly connected to and held firmly in place on the main blower unit. FIG. 2 shows a schematic view of the user 1 receiving heated and humidified air from an integrated respiratory assistance system 6. The system operates in the same manner as the modular system shown in FIG. 1, except the humidification chamber 4b has been integrated with the blower unit to form the integrated system 6. The user interface 5 shown in FIGS. 1 and 2 is a nasal mask, covering the nose of the user 1. However, it should be noted that in systems of these types, a mask that covers the mouth and nose, a full face mask, a nasal cannula, or any other suitable user interface could be substituted for the nasal mask shown. A mouth-only interface or oral mask could also be used. Also, the patient or user end of the conduit can be connected to a tracheostomy fitting, or an endotracheal intubation. U.S. Pat. No. 7,111,624 includes a detailed description of an integrated system. A ‘slide-on’ water chamber is connected to a blower unit in use. A variation of this design is a slide-on or clip-on design where the chamber is enclosed inside a portion of the integrated unit in use. An example of this type of design is shown in WO 2004/112873, which describes a blower, or flow generator 50, and an associated humidifier 150. For these integrated systems, the most common mode of operation is as follows: air is drawn by the blower through an inlet into the casing which surrounds and encloses at least the blower portion of the system. The blower pressurises the air stream from the flow generator outlet and passes this into the humidifier chamber. The air stream is heated and humidified in the humidifier chamber, and exits the humidifier chamber via an outlet. A flexible hose or conduit is connected either directly or indirectly to the humidifier outlet, and the heated, humidified gases are passed to a user via the conduit. This is shown schematically in FIG. 2. In both modular and integrated systems, the gases provided by the blower unit are generally sourced from the surrounding atmosphere. However, some forms of these systems may be configured to allow a supplementary gas to be blended