This application is divided out of Indian Patent Application number 202217003049 dated 19/01/2022,
which, in turn is the National Phase entry of International (PCT) application number PCT/NZ2020/050072
having International filing date 20/07/2020.
FIELD OF THE INVENTION
Present invention relates to a patient interface for delivering respiratory gas to a patient.
5 In particular, the present invention relates to a non-invasive patient interface.
BACKGROUND
One current treatment for obstructive respiration diseases, such as chronic obstructive
pulmonary disease (COPD -which includes emphysema, refractory asthma and Chronic
10 bronchitis), is non-invasive ventilation (NIV). This treatment applies a positive airway
pressure to the lungs throughout the inhalation and exhalation cycle so as to splint the
airways open. This improves the flow of respiratory gas into and out of the lungs.
However, one side effect of the positive pressure applied in current NIV treatments is
15 that it can make patients uncomfortable and, therefore, less willing to undergo the
treatment. A follow-on effect of the positive pressure is that it requires the patient
interface to be secured firmly to the patient to avoid leakages and, thereby ensure that
the pressure is maintained in the patient interface and the respiratory system. Such firm
application of the interface can cause pressure sores, particularly for patients that are
20 semi-conscious or unconscious and, therefore, are unable to provide feedback on any
soreness caused by the pressure of the patient interface on their skin.
The NIV treatment gives rise to two challenges, namely compliance (the extent to which
patients are willing to submit to the treatment) and pressure sores. In addition to these
25 challenges, a further challenge for patients with obstructive respiration diseases is
flushing carbon dioxide out of anatomical dead space. Specifically, the end of the
exhalation cycle is characterised by a reduction in pressure of the exhaled respiratory
gas. This means that the carbon dioxide-loaded respiratory gas remains in the throat,
nose and mouth of the patient and is pulled back into the lungs at the commencement of
30 the inhalation cycle. Replacing the carbon dioxide-loaded respiratory gas in these regions
with respiratory gas that includes oxygen in suitable concentrations for treating
obstructive respiration diseases therefore assists patients.
It is desirable to provide a patient interface that improves patient comfort and that
35 reduces pressure sores.
It is also desirable to provide a patient interface that assists with flushing anatomical
dead space.
2
SUMMARY OF THE INVENTION
The present invention will now be described by way of a set of embodiments in which the
invention may be defined by the features of each embodiment exclusively. However, it
5 will also be appreciated that the invention may be defined by the features of two or more
of the embodiments.
According to a first aspect, there is provided a non-invasive patient interface having a
seal member which is shaped to encompass a mouth and nares of a patient, the
10 interface defining:
(a) a primary flow path to communicate respiratory gas from a gas source to each of
the mouth and the nares separately, and
15 (b) a flushing flow path to communicate respiratory gas from the primary flow path
and/or from the gas source to the nares.
The primary flow path may include a primary flow cavity having one or more primary
flow inlets for respiratory gas and having one or more primary flow outlets to deliver the
20 respiratory gas to each of the mouth and the nares.
25
The primary flow path may include a primary flow cavity having one or more primary
flow inlets for respiratory gas and having one or more primary flow outlets to deliver the
respiratory gas to each of the mouth and the nares separately.
The flushing flow path may include a flushing flow cavity having one or more flushing
flow inlets for respiratory gas and one or more flushing flow outlets to deliver the
respiratory gas to the nares of a patient.
30 The interface may include a mask housing and wherein at least one of the one or more
primary flow inlets is in the housing.
The primary flow cavity may be formed by the seal member and the housing.
35 At least one of the one or more primary flow inlets may be formed in the mask housing.
The patient interface may include one or more of the flushing flow inlets in the seal
member.
3
The interface may include one or more of the flushing flow inlets in the mask housing.
The flushing flow cavity may be a bifurcated cavity having one flushing fluid inlet, two
5 passages downstream of a bifurcation and respective flushing flow outlets at a
downstream end of each of the passages.
The flushing flow cavity may be integrally formed with the seal member.
10 The flushing flow outlets may be flush with primary flow outlets to the nares.
The flushing flow outlets may be recessed within the primary flow cavity from the one or
more primary flow outlets to the nares.
15 The flushing flow cavity may be shaped to direct respiratory gas into the nares.
The flushing flow cavity may be shaped to accelerate respiratory gases into the nares.
The flushing flow cavity may be defined by a cavity wall extending between the one or
20 more flushing flow inlets and the one or more flushing flow outlets.
The flushing flow cavity may be defined by the cavity wall and the outer wall of the seal
member.
25 The flushing flow cavity may be configured to accelerate the respiratory gas. The
acceleration of the respiratory gas is an increase in the velocity of the respiratory gas.
References, throughout this specification and the claims, to acceleration of the
respiratory gas are taken to have the same meaning, unless indicated otherwise.
30 The seal member may have a first primary flow outlet defined by a first portion of the
mask seal which forms a seal or substantially forms a seal surrounding the mouth of the
patient and a second primary flow outlet defined by a second portion of the mask seal
which forms a seal or substantially forms a seal around the nares of the patient.
35 The seal member may be a resilient material and may be connected to the mask housing
to form a unitary structure.
4