DESC:TECHNICAL FIELD
[001] The present disclosure generally relates to the field of medical devices.
Particularly, the present disclosure relates to the field of ventilator systems for
providing respiratory assistance to patients. More particularly, the present disclosure
relates to a medical ventilator having an improved airflow 5 control system.
BACKGROUND
[002] The information in this section merely provides background information related
to the present disclosure and may not constitute prior art(s) for the present disclosure.
10 [003] Patients that have respiratory difficulties often must be placed on a mechanical
ventilator. These difficulties may be pathological in nature or may be due to the fact
that a patient is too weak or sedated to independently perform proper respiration
functions. Often, the patient may be spontaneously attempting to breathe, but not able
to complete a full respiratory cycle. In these cases, mechanically assisted ventilation is
15 provided. In mechanically assisted ventilation, a combination of pressure and/or flow
sensors detects a patient's breath attempt. This detection triggers the delivery of a
mechanical breath, which is provided in the inspiratory phase by the delivery of a pulse
or plug of medical gases under a pressure that is sufficient to overcome the resistance
of the patient's airway, thus filling the lungs. When this pulse of medical gas is
20 discontinued, the natural compliance of the patient's chest wall forces the delivered
breath out of the patient in an expiratory phase.
[004] In order to control the ventilation process, the air pressure and velocity need to
be measured both during the patient inhalation and exhalation cycles. Further, to
ventilate at a preset pressure and flow, the air pressure and volumetric flow rate that are
25 delivered to the patient have to be controlled. However, the flow sensors associated
with ventilators can be adversely affected by moisture contained in the air exhaled by
the patient. If the exhaled air comes in contact with a cool surface, such as the exhalation
valve and flow/ pressure sensor associated therewith, the moisture condenses and
interferes with the function of the flow/ pressure sensor, and in some instances, the
30 exhalation and/or inhalation valves.
[005] For instance, in neonatal ventilation applications, flow rates are typically
measured using proximal flow sensors. These flow sensors measure differential
pressure close to the patient for improved accuracy and are therefore exposed to
moisture from the patient, which is undesirable. Known solutions for preventing
3
exposure of the sensor element to moisture or other contaminants include maintaining
a positive gas flow away from the sensor, but within margins of error of the sensor. To
provide the desired positive gas flow, currently known devices include pressure
regulators, accumulator tanks or acquiring the gas from blower fans. However, said
devices possess various technical difficulties, for example, accumulator 5 tanks require a
large amount of space, pressure regulators need to be checked at assembly as well as
periodically to ensure no error, blower fans require additional active powered
components, difficulties in manufacturability and assembly of the components, and
significantly high costs involved in manufacturing of the components.
10 [006] Typically, the ventilation system includes a nasal cannula control system used
with a ventilator adapted to deliver a supply of ventilation gas to a patient breathing
circuit to provide mechanical ventilation of the patient. The patient breathing circuit
includes a non-invasive ventilation breathing mask that is used to deliver gases to the
patient. The breathing mask may cover both the nose and mouth of the patient and form
15 a seal with the patient along the outer peripheral edges of the breathing mask. The
breathing mask includes an inlet that receives pressurized gases from the ventilator
during the inspiratory phase of the patient breathing cycle and provides an outlet path
for the exhaled gases from the patient to the ventilator during the expiratory phase of
the breathing cycle. Further, a nasal cannula is positioned in the nostrils of the patient
20 to either deliver a flow of gases to the patient or to sense the pressure within the nostrils
of the patient and within the mask. The nasal cannula control system includes a
monitoring unit that interfaces with the nasal cannula assembly including two separate
lumens - a nasal lumen that is in pneumatic communication with the patient's nostrils
and a mask lumen that is in pneumatic communication with the interior of the patient's
25 breathing mask. The nasal cannula control system is configured to utilize the
combination of the nasal lumen and the mask lumen to monitor the pressure within the
patient mask and nostrils of the patient, as well as to monitor an exhaled gas from the
patient.
[007] Said nasal cannula control system utilizes a differential pressure sensor to
30 determine pressure value in the nasal lumen and/ or the mask lumen and control the
flow rate of gases to the patient. As discussed above, the moisture content contained in
the exhaled air of the patient may interfere with the differential pressure sensor and alter
the readings thereof. Currently deployed solution to purge the moisture content from
the system includes using off the shelf orifice device(s) in the flow path proximal to the
4
differential pressure sensor. The orifice device(s) is adapted to facilitate enough
resistance to gas flow so as to provide positive gas flow directed away from the
differential pressure sensor. However, it is practically hard to accomplish the relatively
low flow rates required as the sizes of the orifice device/ restrictor required to create
these low flow rates are impossible or extremely 5 difficult to machine.
[008] Accordingly, there remains a need in the domain to devise an airflow control
system for a medical ventilator that is inclusive of components having relatively smaller
size and composed of off the shelf and readily available components, is easy to integrate
in the medical ventilator, requires no or minimal adjustments during assembly, has
10 rugged construction with no moving parts, offers improved service life and minimal
maintenance requirements, has reduced possibility of failure, etc.
SUMMARY
[009] The one or more shortcomings of the prior art are overcome by the system/
15 assembly as claimed, and additional advantages are provided through the provision of
the system/ assembly/ method as claimed in the present disclosure. Additional features
and advantages are realized through the techniques of the present disclosure. Other
embodiments and aspects of the disclosure are described in detail herein and are
considered a part of the claimed disclosure.
20 [010] Pursuant to an aspect of the present disclosure, a ventilator system for
respiratory assistance to a patient is disclosed. The ventilator system comprises an air
conduit for supplying air in an inhalation side of a breathing circuit, an oxygen conduit
for supplying oxygen in the inhalation side of the breathing circuit, and a mixing
chamber coupled to the air conduit and the oxygen conduit for receiving air and oxygen.
25 The mixing chamber is adapted to form an inhalation charge therein. The ventilator
system further comprises a patient breathing interface fluidly coupled with the mixing
chamber to receive the inhalation charge. The patient breathing interface is adapted to
supply the inhalation charge to the patient, and receive an exhalation charge from the
patient. The ventilator system furthermore comprises a flow element coupled with the
30 patient breathing interface. The flow element is adapted to determine one or more
characteristics of the inhalation charge and the exhalation charge in the patient
breathing interface. Further, the ventilator system comprises an airflow control system
coupled to the air conduit or the oxygen conduit at one end and coupled to the flow
element at the other end. The airflow control system is configured to receive a part of
5
air or oxygen from the air conduit or the oxygen conduit, via a bypass conduit, and
purge the flow element with the part of air or oxygen.
[011] In another non-limiting embodiment of the present disclosure, the airflow
control system is configured to generate a positive gas flow with the part of air or
oxygen to purge moisture and/ or contaminants contained in 5 the exhalation charge
expelled from the patient.
[012] In another non-limiting embodiment of the present disclosure, the airflow
control system comprises a plurality of orifices arranged with each other either in series,
or parallel, or in parallel-series combination.
10 [013] In another non-limiting embodiment of the present disclosure, the airflow
control system comprises a first set of orifices and a second set of orifices. The first set
of orifices comprises one orifice (O1), the second set of orifices comprises two orifices
(O2, O3) arranged parallel to each other, and the first set of orifices is arranged in series
combination with the second set of orifices.
15 [014] In another non-limiting embodiment of the present disclosure, the airflow
control system comprises a first purge conduit and a second purge conduit. The first
purge conduit is coupled with a feed line containing a first probe of the flow element
for measuring pressure in a nasal lumen of the patient breathing interface. The second
purge conduit is coupled with a feed line containing a second probe of the flow element
20 for measuring pressure in a mask lumen of the patient breathing interface. The first
purge conduit and the second purge conduit are adapted to provide a positive gas flow
directed away from the first probe and the second probe of the flow element.
[015] In another non-limiting embodiment of the present disclosure, the airflow
control system comprises an outlet conduit for expelling a remaining portion of air or
25 oxygen into the atmosphere.
[016] In another non-limiting embodiment of the present disclosure, the air conduit is
coupled to an air source for supplying air in the inhalation side of the breathing circuit.
Further, the oxygen conduit is coupled to an oxygen source for supplying oxygen in the
inhalation side of the breathing circuit. Also, the air source and the oxygen source are
30 maintained at a high pressure.
[017] In another non-limiting embodiment of the present disclosure, the ventilator
system comprises a pressure regulator valve provided in the air conduit to control
pressure of air received from the air source. Further, the ventilator system comprises a
6
pressure regulator valve provided in the oxygen conduit to control pressure of oxygen
received from the oxygen source.
[018] In another non-limiting embodiment of the present disclosure, the ventilator
system comprises an inhale fluid conduit that fluidly couples an output end of the
mixing chamber with the patient breathing interface. Further, 5 the ventilator system
comprises an exhale fluid conduit fluidly coupled to the patient breathing interface for
expelling the exhalation charge into the atmosphere.
[019] In another non-limiting embodiment of the present disclosure, the flow element
is a differential pressure flow sensor.
10 [020] In another non-limiting embodiment of the present disclosure, the patient
breathing interface is endotracheal (ET) tube, ventilator face mask, or nasal mask.
[021] In another non-limiting embodiment of the present disclosure, the one or more
characteristics measured by the flow element comprises flow rate, velocities, pressure,
and temperature.
15 [022] Within the scope of the present disclosure, the airflow control system for the
medical ventilator system is inclusive of components having relatively smaller size and
composed of off-the-shelf and readily available components, is easy to integrate in the
medical ventilator, requires no or minimal adjustments during assembly, has rugged
construction with no moving parts, offers improved service life and minimal
20 maintenance requirements, has reduced possibility of failure, etc.
[023] It is to be understood that the aspects and embodiments of the disclosure
described above may be used in any combination with each other. Several of the aspects
and embodiments may be combined together to form a further embodiment of the
disclosure.
25 [024] The foregoing summary is illustrative only and is not intended to be in any way
limiting. In addition to the illustrative aspects, embodiments, and features described
above, further aspects, embodiments, and features will become apparent by reference
to the drawings and the following detailed description.
30 BRIEF DESCRIPTION OF FIGURES
[025] The novel features and characteristics of the disclosure are set forth in the
description. The disclosure itself, however, as well as a preferred mode of use, further
objectives, and advantages thereof, will best be understood by reference to the
following description of an illustrative embodiment when read in conjunction with the
7
accompanying drawings. One or more embodiments are now described, by way of
example only, with reference to the accompanying drawings wherein like reference
numerals represent like elements and in which:
[026] FIG. 1 illustrates a schematic view of a medical ventilator, 5 depicting various
components thereof, in accordance with an embodiment of the present disclosure.
[027] Skilled artisans will appreciate that elements in the drawings are illustrated for
simplicity and have not necessarily been drawn to scale. For example, the dimensions
10 of some of the elements in the drawings may be exaggerated relative to other elements
to help to improve understanding of embodiments of the present disclosure.
DETAILED DESCRIPTION
[028] While the disclosure is susceptible to various modifications and alternative
15 forms, specific embodiments thereof have been shown by way of example in the FIGS.
and will be described in detail below. It should be understood, however that it is not
intended to limit the disclosure to the particular forms disclosed, but on the contrary,
the disclosure is to cover all modifications, equivalents, and alternatives falling within
the scope of the disclosure as defined by the appended claims.
20 [029] Before describing detailed embodiments, it may be observed that the novelty
and inventive step that are in accordance with the present disclosure resides in a
ventilator system for respiratory assistance to a patient. It is to be noted that a person
skilled in the art can be motivated from the present disclosure and modify the various
constructions of the ventilator system. However, such modification should be construed
25 within the scope of the present disclosure. Accordingly, the drawings are showing only
those specific details that are pertinent to understanding the embodiments of the present
disclosure so as not to obscure the disclosure with details that will be readily apparent
to those of ordinary skill in the art having benefit of the description herein.
[030] In the present disclosure, the term “exemplary” is used herein to mean “serving
30 as an example, instance, or illustration.” Any embodiment or implementation of the
present subject matter described herein as “exemplary” is not necessarily to be
construed as preferred or advantageous over other embodiments.
[031] The terms “comprises”, “comprising”, or any other variations thereof, are
intended to cover non-exclusive inclusions, such that a device that comprises a list of
8
components does not include only those components but may include other components
not expressly listed or inherent to such setup or device. In other words, one or more
elements in a system or apparatus proceeded by “comprises… a” does not, without more
constraints, preclude the existence of other elements or additional elements in the
5 system or apparatus.
[032] The terms like “at least one” and “one or more” may be used interchangeably
or in combination throughout the description.
[033] In an aspect of the present disclosure, a ventilator system for respiratory
assistance to a patient is disclosed. The ventilator system comprises an air conduit for
10 supplying air in an inhalation side of a breathing circuit, an oxygen conduit for
supplying oxygen in the inhalation side of the breathing circuit, and a mixing chamber
coupled to the air conduit and the oxygen conduit for receiving air and oxygen. The
mixing chamber is adapted to form an inhalation charge therein. The ventilator system
further comprises a patient breathing interface fluidly coupled with the mixing chamber
15 to receive the inhalation charge. The patient breathing interface is adapted to supply the
inhalation charge to the patient, and receive an exhalation charge from the patient. The
ventilator system furthermore comprises a flow element coupled with the patient
breathing interface. The flow element is adapted to determine one or more
characteristics of the inhalation charge and the exhalation charge in the patient
20 breathing interface. Further, the ventilator system comprises an airflow control system
coupled to the air conduit or the oxygen conduit at one end and coupled to the flow
element at the other end. The airflow control system is configured to receive a part of
air or oxygen from the air conduit or the oxygen conduit, via a bypass conduit, and
purge the flow element with the part of air or oxygen.
25 [034] The airflow control system is configured to generate a positive gas flow with
the part of air or oxygen to purge moisture and/ or contaminants contained in the
exhalation charge expelled from the patient. The airflow control system comprises a
plurality of orifices arranged with each other either in series, or parallel, or in parallelseries
combination. In an embodiment, the airflow control system comprises a first set
30 of orifices and a second set of orifices. The first set of orifices comprises one orifice
(O1), the second set of orifices comprises two orifices (O2, O3) arranged parallel to
each other, and the first set of orifices is arranged in series combination with the second
set of orifices.
9
[035] Further, the airflow control system comprises a first purge conduit and a second
purge conduit. The first purge conduit is coupled with a feed line containing a first
probe of the flow element for measuring pressure in a nasal lumen of the patient
breathing interface. The second purge conduit is coupled with a feed line containing a
second probe of the flow element for measuring pressure in a mask 5 lumen of the patient
breathing interface. The first purge conduit and the second purge conduit are adapted
to provide a positive gas flow directed away from the first probe and the second probe
of the flow element. The airflow control system further comprises an outlet conduit for
expelling a remaining portion of air or oxygen into the atmosphere.
10 [036] In an embodiment, the air conduit is coupled to an air source for supplying air
in the inhalation side of the breathing circuit. Further, the oxygen conduit is coupled to
an oxygen source for supplying oxygen in the inhalation side of the breathing circuit.
Also, the air source and the oxygen source are maintained at a high pressure. Further,
the ventilator system comprises a pressure regulator valve provided in the air conduit
15 to control pressure of air received from the air source. Furthermore, the ventilator
system comprises a pressure regulator valve provided in the oxygen conduit to control
pressure of oxygen received from the oxygen source.
[037] The ventilator system comprises an inhale fluid conduit that fluidly couples an
output end of the mixing chamber with the patient breathing interface. Further, the
20 ventilator system comprises an exhale fluid conduit fluidly coupled to the patient
breathing interface for expelling the exhalation charge into the atmosphere. In an
embodiment, the flow element is a differential pressure flow sensor. Also, the patient
breathing interface is endotracheal (ET) tube, ventilator face mask, or nasal mask. The
one or more characteristics measured by the flow element comprises flow rate,
25 velocities, pressure, and temperature.
[038] Reference will now be made to the exemplary embodiments of the disclosure,
as illustrated in the accompanying drawings. Wherever possible, same numerals will be
used to refer to the same or like parts. Embodiments of the disclosure are described in
the following paragraphs with reference to FIG. 1.
30 [039] Embodiments of the disclosure are described in the following paragraphs with
reference to FIG. 1. Referring to FIG.1, a schematic view of a medical ventilator system
(10) (herein after, referred to as “ventilator system”) according to an embodiment of
the present disclosure is shown. Within the scope of the present disclosure, the
ventilator system (10) of the present disclosure may include a housing (not shown) with
10
a touch screen to control one or more operations of the ventilator system (10), provide
patient information, and provide feedback from one or more sensors associated with the
ventilator system (10) to monitor a patient’s breathing pattern. The ventilator system
(10) may further include an inhalation valve assembly and an exhalation valve assembly
which, through use of tubing to the patient, places the medical ventilator 5 system (10) in
fluid communication with the patient.
[040] The ventilator system (10) of the present disclosure may comprise one or more
turbine assemblies (not shown), each of which includes a turbine and drive motor to
create a positive air/ gas flow towards the patient in an inhalation side of the breathing
10 circuit (12). The ventilator system (10) may further include pressure regulators
associated with a corresponding turbine assembly and adapted to control/ regulate
pressure of air/ gas in the inhalation side of the breathing circuit (12), control valves to
control air/ gas flow in the form of a proportional obstacle valve having a movable valve
operated by a stepper motor coupled to the proportional obstacle valve, a high pressure
15 box, a mixing chamber, an inhalation valve and strut to provide a one-way path for
airflow/ gases to the patient. The ventilator system (10) may further comprise an
exhalation valve and strut to receive exhaled air from the patient.
[041] In accordance with the present disclosure, the airflow path to the patient may
additionally comprise an air filter (not shown). The ventilator system (10) may be
20 adapted to draw ambient air into the breathing circuit (12) through the inlet air filter in
fluid communication with an inlet of the turbine intake. Thus, air provided to the patient
is filtered upon entry into the ventilator system (10) as well as prior to being output to
the patient. Additionally, to cool the turbine during operation, the turbine assembly may
be provided with an internal heat sink. A cooling fan may be used to blow air over the
25 turbine assembly.
[042] Within the scope of the present disclosure, the ventilator system (10) is
configured to provide respiratory assistance to patients. In illustrated FIG. 1, the
ventilator system (10) comprises two conduits, namely an air conduit (21) and an
oxygen conduit (31) so as to comprise two fluid flow paths, namely, an air path (20)
30 and an oxygen path (30). In accordance with the present disclosure, the air conduit (21)
is configured for supplying air in an inhalation side of the breathing circuit (12) and the
oxygen conduit (31) is configured for supplying oxygen in the inhalation side of the
breathing circuit (12).
11
[043] Further, the ventilator system (10) comprises a mixing chamber (40) in the
inhalation side of the breathing circuit (12). The mixing chamber (40) is adapted to be
coupled to the air conduit (21) and the oxygen conduit (31) such that the air path (20)
and the oxygen path (30) merge with each other at the mixing chamber (40) to provide
a metered air-oxygen mixture to the patient. The mixing chamber (5 40) is configured to
receive air and oxygen, from the air conduit (21) and the oxygen conduit (31),
respectively, to form an inhalation charge therein.
[044] As illustrated, the air path (20) and the oxygen path (30) originate from an air
source (22) and an oxygen source (32), respectively. In accordance with the present
10 disclosure, the air conduit (21) is coupled to the air source (22) for supplying air in the
inhalation side of the breathing circuit (12), and the oxygen conduit (31) is coupled to
the oxygen source (32) for supplying oxygen in the inhalation side of the breathing
circuit (12). Each of the air source (22) and the oxygen source (32) is maintained at a
high pressure, for example, at 4 bar pressure, in the hospital premises to supply air and
15 oxygen, respectively, to a plurality of medical ventilator systems in the hospital. The
air source (22) and the oxygen source (32) may be coupled with a respective turbine
assembly (not shown) which is driven by a motor to supply air/ oxygen in the air/
oxygen path (20, 30) of the medical ventilator system (10). The ventilator system (10)
may further comprise pressure regulator valves provided in the air path (20) and the
20 oxygen path (30) to control/ reduce pressure of the air/ oxygen received from the air
source/ oxygen source (22, 32). For example, in the illustrated embodiment of the
present disclosure, the ventilator system (10) comprises a pressure regulator valve (24)
disposed in the air conduit (21) and a pressure regulator valve (34) disposed in the
oxygen conduit (31), respectively. The pressure regulator valve (24) and the pressure
25 regulator valve (34) are configured to control/ regulate the pressure of air and oxygen
in the air path (20) and the oxygen path (30), respectively, according to the requirement
of fluid in the breathing circuit (12). In the illustrated embodiment, the pressure
regulator valves (24, 34) have been shown to reduce/ regulate the pressure of air and
oxygen to 1.5 bar.
30 [045] In the downstream direction of the air path (20) and the oxygen path (30),
proportional valves may be provided in the ventilator system (10). The proportional
valves may be disposed downstream of the pressure regulator valves (24, 34). As
illustrated in FIG. 1, a proportional valve (26) is provided downstream of the pressure
regulator valve (24) in the air path (20). Similarly, a proportional valve (36) is provided
12
downstream of the pressure regulator valve (34) in the oxygen path (30). Each of the
proportional valves (26, 36) is adapted to regulate flow/ quantity of air or oxygen in the
breathing circuit (12). An output of each of the proportional valve (26, 36) of the air
path (20) and the oxygen path (30) may be connected to the mixing chamber (40) to
supply desired/ required flow/ quantity of air and oxygen in the 5 mixing chamber (40)
and form an air-oxygen mixture to be circulated in the inhalation side of the breathing
circuit (12) and to be provided to the patient.
[046] The ventilator system (10) further comprises an inhale fluid conduit (42) that
fluidly couples an output end of the mixing chamber (40) with a patient breathing
10 interface (60) of the ventilator system (10). The patient breathing interface (60) may
comprise, but not limited to, endotracheal (ET) tube, ventilator face mask, or nasal
mask, or any other suitable device adapted to be worn by the patient or coupled to the
respiratory system of the patient. The patient breathing interface (60) is fluidly coupled
with the mixing chamber (40) to receive the inhalation charge. The patient breathing
15 interface (60) is adapted to receive the air-oxygen mixture (i.e., the inhalation charge)
from the ventilator system (10), i.e., the mixing chamber (40), and supply the same to
the patient’s lungs as the inhalation charge. Also, the patient breathing interface (60) is
adapted to receive an exhalation charge from the patient’s lungs and supply the same to
an exhalation side of the breathing circuit (12) of the ventilator system (10). A plurality
20 of sensors or check valves (44) or regulator valves may be disposed on the fluid flow
path between the mixing chamber (40) and the patient breathing interface (60) to
determine and/ or regulate the characteristics, for example, pressure, velocity, flow rate,
temperature, etc., of the air-oxygen mixture being supplied to the patient breathing
interface (60) from the mixing chamber (40) of the ventilator system (10).
25 [047] The exhalation side of the ventilator system (10) includes an exhale fluid
conduit (46) that is adapted to be fluidly coupled to the patient breathing interface (60)
and couple the patient breathing interface (60) with the ventilator system (10). The
exhale fluid conduit (46) is configured to facilitate supplying the exhalation charge from
the patient’s lungs to the ventilator system (10). In an embodiment, the exhale fluid
30 conduit (46) may facilitate discharging/ expelling the exhalation charge into the
atmosphere. A valve (48) may be disposed on the exhale fluid conduit (46) to control/
regulate the pressure of exhalation charge being released into the atmosphere or the
ventilator system (10), as indicated in FIG. 1.
13
[048] Within the scope of the present disclosure, the ventilator system (10) comprises
a flow element (50) coupled with the patient breathing interface (60). Further, in an
embodiment, the flow element (50) is adapted to be coupled to the inhale fluid conduit
(42) and the exhale fluid conduit (46) of the ventilator (10), as shown in FIG. 1. The
flow element (50) is adapted to determine/ sense one or more characteristics 5 of the
inhalation charge supplied to the patient breathing interface (60) and that of the
exhalation charge expelled from the patient’s lungs. The characteristics determined/
sensed by the flow element (50) may include, but not limited to, flow rate, velocities,
pressure, temperature, etc.
10 [049] In an exemplary embodiment of the present disclosure, the patient breathing
interface (60) is embodied as a face mask (not shown) and the flow element (50) is
embodied as a differential pressure flow sensor (50) fluidly coupled with the face mask,
i.e., the patient breathing interface (60). The face mask comprises a nasal lumen and a
mask lumen. The nasal lumen of the face mask is adapted to be in fluid/ pneumatic
15 communication with the patient’s nostrils, and the mask lumen is adapted to be in fluid/
communication with an interior of the face mask worn by the patient. Although, the
nasal lumen and the mask lumen are described as extending to defined areas, namely
the nostrils and the interior of the face mask, the lumens could terminate at other
locations depending upon the specific patient and the configuration of the patient
20 breathing circuit (12)/ ventilator system (10). The differential pressure flow sensor (50)
is configured to measure the pressure in the nasal lumen and the mask lumen and utilize
the combination of pressures measured by the nasal lumen and the mask lumen to
monitor the pressure within the patient mask and nostrils of the patient, as well as to
monitor an exhaled gas/ exhalation charge from the patient, such as the carbon dioxide
25 concentration within the nasal canal of the patient. However, there exists instances
wherein the moisture and/ or contaminants contained in the exhalation charges from the
patient’s lungs interferes with the working of the pressure differential flow sensor (50).
[050] In accordance with the present disclosure, the ventilator system (10) comprises
an airflow control system (100) to purge the moisture and/ or contaminants contained
30 in the exhalation charges expelled from the patient’s lungs. Within the scope of the
present disclosure, the airflow control system (100) is adapted to facilitate a positive
gas flow that is directed away from the differential pressure flow sensor (50),
specifically, the measuring probes of the differential pressure flow sensor (50), to
14
prevent moisture from reaching the differential pressure flow sensor (50) but that does
not alter or interfere with the measurements of the differential pressure flow sensor (50).
[051] With reference to FIG. 1, the airflow control system (100) has been illustrated.
In an embodiment, the airflow control system (100) is coupled to the air conduit (21) at
one end and coupled to the flow element (50) at the other end. In 5 another embodiment,
the airflow control system (100) is coupled to the oxygen conduit (31) at one end and
coupled to the flow element (50) at the other end. In accordance with the present
disclosure, the airflow control system (100) is disposed downstream of the air path (20)
or the oxygen path (30) by way of a bypass conduit (102). Within the scope of the
10 present disclosure, the airflow control system (100) is configured to receive a part of
air or oxygen from the air conduit (21) or the oxygen conduit (31), via the bypass
conduit (102). In an embodiment where the airflow control system (100) is coupled to
the air conduit (21), the airflow control system (100) is configured to receive a part of
air from the air conduit (21), via the bypass conduit (102). In an embodiment where the
15 airflow control system (100) is coupled to the oxygen conduit (31), the airflow control
system (100) is configured to receive a part of oxygen from the oxygen conduit (31),
via the bypass conduit (102).
[052] Further, the airflow control system (100) is configured to purge the flow element
(50) with the part of air or oxygen received from the bypass conduit (102). In
20 accordance with the present disclosure, the airflow control system (100) is configured
to generate a positive gas flow with the part of air or oxygen to purge moisture and/ or
contaminants contained in the exhalation charge expelled from the patient/ patient’s
lungs.
[053] The airflow control system (100) is fluidly coupled with the differential pressure
25 flow sensor (50), i.e., the flow element (50) of the ventilator system (10). The airflow
control system (100) is configured to provide at least a portion of oxygen/ air bypassed
from the oxygen conduit (31) or the air conduit (21) towards the differential pressure
flow sensor (50) so as to generate the positive gas flow for purging purposes. In the
illustrated exemplary embodiment, the airflow control system (100) comprises two
30 purge conduits, namely a first purge conduit (110) and a second purge conduit (120).
The first purge conduit (110) is coupled with a feed line containing a first probe (of the
flow element (50)) for measuring pressure in the nasal lumen of the patient breathing
interface (60) or the face mask. The second purge conduit (120) is coupled with a feed
line containing a second probe (of the flow element (50)) for measuring pressure in the
15
mask lumen of the patient breathing interface (60) or the face mask. Each of the first
purge conduit (110) and the second purge conduit (120) is adapted to provide the
positive gas flow directed away from the first and second measuring probes of the
differential pressure flow sensor (50).
[054] Further, the airflow control system (100) comprises an outlet 5 conduit (104) for
expelling the remaining portion of oxygen/ air out of the airflow control system (100)
and into the atmosphere.
[055] Within the scope of the present disclosure, to generate a desired positive gas
flow in the airflow control system (100) that prevent moisture from reaching the
10 differential flow sensor (50)/ probes but that does not alter or interfere with the
measurements of the differential pressure flow sensor (50), the airflow control system
(100) of the present disclosure comprises a plurality of orifices arranged with each other
either in series, or parallel, or in parallel-series combination. In an embodiment, the
airflow control system (100) comprises two sets of orifices, as shown in FIG. 1. The
15 two sets of orifices may be arranged with each other either in series, or parallel, or in
parallel series combination. Said combination of the sets of orifices offers to use/
employ off-the-shelf orifice devices and create larger resistance for the flow of bypass
gas, for example, the part of air or oxygen, to generate desired positive gas flow for
purging of the differential pressure flow sensor (50). In the illustrated exemplary
20 embodiment of FIG. 1, the two sets of orifices are shown as a first set of orifices (130)
comprised of orifice (O1), and a second set of orifices (140) comprised of orifice (O2)
and orifice (O3). As illustrated, the second set of orifices (140) is comprised of a parallel
arrangement of the orifices (O2) and (O3), and said second set of orifices (140) is
arranged in series with the first set of orifices (130) or the orifice (O1).
25 [056] Within the scope of the present disclosure, the parallel arrangement of the
orifices (O2) and (O3) results in a much larger drop of flow rate across the second set
of orifices (140) compared to each of the individual orifices (O2) and (O3), for the
reason that the resultant diameter or the area of cross-section across the parallel
arrangement of the orifices (O2) and (O3) comes out to be lesser than the diameter or
30 the area of cross-section of the individual orifices (O2) and (O3). The determination of
the resultant diameter or the area of cross-section of a parallel arrangement or a series
arrangement of orifices can be construed analogous to determining a resultant resistance
across a parallel arrangement or a series arrangement of resistances in electrical circuits.
Also, since the flow rate across an orifice is inversely proportional to square of diameter
16
of the orifice, a much narrower diameter would offer high resistance to flow rate of gas
and thus would facilitate controlling the flow rate/ pressure to generate the desired
positive gas flow for purging of moisture in the differential pressure flow sensor (50)
associated with the face mask or the patient breathing interface (60).
[057] Referring to FIG. 1, the airflow control system (100) receives 5 the part of air or
oxygen from the air conduit (21) or the oxygen conduit (31), respectively, and said part
of air or oxygen is made to flow across the first set of orifice (130) or the orifice (O1),
thereby reducing the pressure of the part of air or oxygen to a value less than the
pressure of air or oxygen at the hospital air source or oxygen source (32) or at the
10 pressure regulator valves (24, 34). Subsequently, the part of air or oxygen (of reduced
pressure) is made to flow across the second set of orifices (140) comprised of the
parallel arrangement of the orifices (O2) and (O3). As discussed above, the second set
of orifices (140) offers larger resistance to gas flow and thus reduce the pressure of air
or oxygen to a value that generate the desired positive gas flow for purging of moisture
15 in the differential pressure flow sensor (50) but that does not alter or interfere with the
operation of measuring probes of the sensors.
[058] According to the present disclosure, the airflow control system (100) for the
medical ventilator (10) is inclusive of components having relatively smaller size and
composed of off-the-shelf and readily available components, is easy to integrate in the
20 medical ventilator, requires no or minimal adjustments during assembly, has rugged
construction with no moving parts, offers improved service life and minimal
maintenance requirements, has reduced possibility of failure, etc.
[059] The table below provides a few exemplary embodiments of the airflow control
system (100) having varying configurations of the orifices (O1), (O2), and (O3), and
25 corresponding flow rate/ pressure characteristics:
17
18
[060] The calculations for estimating the flow rates of the embodiments of the airflow
control system (100) can also be adapted to include the difference in pressures between
the outlet conduit (104) and the purge conduits (110, 120). This pressure difference
exists due to the nature of providing mechanical ventilation 5 to a patient, usually
requiring pressures above atmospheric in the breathing circuit (12) and fluid conduit
(46) to inflate the patient’s lungs. Thus, purge conduits (110, 120) are venting into this
higher pressure with respect to the outlet conduit (104). Depending on the range of
difference in pressures expected between the outlet conduit (104) and the purge
10 conduits (110, 120), this adaptation may be used to obtain calculation results that more
appropriately represent the system (100). This calculation can also influence the
selection of the orifices (130, 140). This is taken into account in the Cases I, II, III in
the table above to illustrate the effect.
[061] The various embodiments of the present disclosure have been described above
15 with reference to the accompanying drawings. The present disclosure is not limited to
the illustrated embodiments; rather, these embodiments are intended to fully and
completely disclose the subject matter of the disclosure to those skilled in this art. In
the drawings, like numbers refer to like elements throughout. Thicknesses and
dimensions of some components may be exaggerated for clarity.
20 [062] Herein, the terms “attached”, “connected”, “interconnected”, “contacting”,
“mounted”, “coupled” and the like can mean either direct or indirect attachment or
contact between elements, unless stated otherwise.
[063] Well-known functions or constructions may not be described in detail for
brevity and/or clarity. As used herein the expression “and/or” includes any and all
25 combinations of one or more of the associated listed items.
[064] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the disclosure. As used herein,
the singular forms “a”, “an” and “the” are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further understood that the
30 terms “comprises”, “comprising”, “includes” and/or “including” when used in this
specification, specify the presence of stated features, operations, elements, and/or
components, but do not preclude the presence or addition of one or more other features,
operations, elements, components, and/or groups thereof.
19
[065] While considerable emphasis has been placed herein on the particular features
of this disclosure, it will be appreciated that various modifications can be made, and
that many changes can be made in the preferred embodiments without departing from
the principles of the disclosure. These and other modifications in the nature of the
disclosure or the preferred embodiments will be apparent to those 5 skilled in the art from
the disclosure herein, whereby it is to be distinctly understood that the foregoing
descriptive matter is to be interpreted merely as illustrative of the disclosure and not as
a limitation.
10
20
REFERENCE NUMERALS
PARTICULARS REFERRAL NUMERAL
Ventilator System 10
Breathing circuit 12
Air path 20
Air Conduit 21
Air source 22
Pressure regulator valve 24
Proportional valve 26
Oxygen path 30
Oxygen Conduit 31
Oxygen source 32
Pressure regulator valve 34
Proportional valve 36
Mixing chamber 40
Inhale fluid conduit 42
Check valve 44
Exhale fluid conduit 46
Proportional valve 48
Flow element/ Differential
Pressure Flow Sensor
50
Patient Breathing Interface 60
Airflow control system 100
Bypass conduit 102
Outlet conduit 104
First Purge conduit 110
Second Purge conduit 120
First set of orifices 130
Second set of orifices 140
Orifice O1
Orifice O2
Orifice O3
21
EQUIVALENTS:
[066] The embodiments herein and the various features and advantageous details
thereof are explained with reference to the non-limiting embodiments in the description.
Descriptions of well-known components and processing techniques are omitted so as
to not unnecessarily obscure the embodiments herein. The examples 5 used herein are
intended merely to facilitate an understanding of ways in which the embodiments herein
may be practiced and to further enable those of skill in the art to practice the
embodiments herein. Accordingly, the examples should not be construed as limiting the
scope of the embodiments herein.
10 [067] The foregoing description of the specific embodiments will so fully reveal the
general nature of the embodiments herein that others can, by applying current
knowledge, readily modify and/or adapt for various applications such specific
embodiments without departing from the generic concept, and, therefore, such
adaptations and modifications should and are intended to be comprehended within the
15 meaning and range of equivalents of the disclosed embodiments. It is to be understood
that the phraseology or terminology employed herein is for the purpose of description
and not of limitation. Therefore, while the embodiments herein have been described in
terms of preferred embodiments, those skilled in the art will recognize that the
embodiments herein can be practiced with modification within the spirit and scope of
20 the embodiments as described herein.
[068] Any discussion of documents, acts, materials, devices, articles and the like that
has been included in this specification is solely for the purpose of providing a context
for the disclosure. It is not to be taken as an admission that any or all of these matters
form a part of the prior art base or were common general knowledge in the field relevant
25 to the disclosure as it existed anywhere before the priority date of this application.
[069] The numerical values mentioned for the various physical parameters,
dimensions or quantities are only approximations and it is envisaged that the values
higher/lower than the numerical values assigned to the parameters, dimensions or
quantities fall within the scope of the disclosure, unless there is a statement in the
30 specification specific to the contrary. ,CLAIMS:We Claim:
1. A ventilator system (10) for respiratory assistance to 5 a patient, the ventilator
system (10) comprising:
an air conduit (21) for supplying air in an inhalation side of a breathing
circuit (12);
an oxygen conduit (31) for supplying oxygen in the inhalation side of
10 the breathing circuit (12);
a mixing chamber (40) coupled to the air conduit (21) and the oxygen
conduit (31) for receiving air and oxygen, the mixing chamber (40) adapted to
form an inhalation charge therein;
a patient breathing interface (60) fluidly coupled with the mixing
15 chamber (40) to receive the inhalation charge, the patient breathing interface
(60) adapted to:
supply the inhalation charge to the patient, and
receive an exhalation charge from the patient;
a flow element (50) coupled with the patient breathing interface (60),
20 and adapted to determine one or more characteristics of the inhalation charge
and the exhalation charge in the patient breathing interface (60); and
an airflow control system (100) coupled to the air conduit (21) or the
oxygen conduit (31) at one end and coupled to the flow element (50) at the other
end, wherein the airflow control system (100) is configured to:
25 receive a part of air or oxygen from the air conduit (21) or the
oxygen conduit (31), via a bypass conduit (102), and
purge the flow element (50) with the part of air or oxygen.
2. The ventilator system (10) as claimed in claim 1, wherein the airflow control
30 system (100) is configured to generate a positive gas flow with the part of air or
oxygen to purge moisture and/ or contaminants contained in the exhalation
charge expelled from the patient.
23
3. The ventilator system (10) as claimed in claim 1, wherein the airflow control
system (100) comprises a plurality of orifices arranged with each other either in
series, or parallel, or in parallel-series combination.
4. The ventilator system (10) as claimed in claim 1, wherein 5 the airflow control
system (100) comprises a first set of orifices (130) and a second set of orifices
(140), in which
the first set of orifices (130) comprises one orifice (O1),
the second set of orifices (140) comprises two orifices (O2, O3) arranged
10 parallel to each other, and
the first set of orifices (130) is arranged in series combination with the
second set of orifices (140).
5. The ventilator system (10) as claimed in claim 1, wherein the airflow control
15 system (100) comprises:
a first purge conduit (110) coupled with a feed line containing a first
probe of the flow element (50) for measuring pressure in a nasal lumen of the
patient breathing interface (60), and
a second purge conduit (120) coupled with a feed line containing a
20 second probe of the flow element (50) for measuring pressure in a mask lumen
of the patient breathing interface (60),
wherein the first purge conduit (110) and the second purge conduit (120)
are adapted to provide a positive gas flow directed away from the first probe
and the second probe of the flow element (50).
25
6. The ventilator system (10) as claimed in claim 1, wherein the airflow control
system (100) comprises an outlet conduit (104) for expelling a remaining
portion of air or oxygen into the atmosphere.
30 7. The ventilator system (10) as claimed in claim 1, wherein
the air conduit (21) is coupled to an air source (22) for supplying air in
the inhalation side of the breathing circuit (12),
the oxygen conduit (31) is coupled to an oxygen source (32) for
supplying oxygen in the inhalation side of the breathing circuit (12), and
24
the air source (22) and the oxygen source (32) are maintained at a high
pressure.
8. The ventilator system (10) as claimed in claim 7, wherein the ventilator system
5 (10) comprises
a pressure regulator valve (24) provided in the air conduit (21) to control
pressure of air received from the air source (22), and
a pressure regulator valve (34) provided in the oxygen conduit (31) to
control pressure of oxygen received from the oxygen source (32).
10
9. The ventilator system (10) as claimed in claim 1, wherein the ventilator system
(10) comprises
an inhale fluid conduit (42) that fluidly couples an output end of the
mixing chamber (40) with the patient breathing interface (60), and
15 an exhale fluid conduit (46) fluidly coupled to the patient breathing
interface (60) for expelling the exhalation charge into the atmosphere.
10. The ventilator system (10) as claimed in claim 1, wherein the flow element (50)
is a differential pressure flow sensor (50).
20
11. The ventilator system (10) as claimed in claim 1, wherein the patient breathing
interface (60) is endotracheal (ET) tube, ventilator face mask, or nasal mask.
12. The ventilator system (10) as claimed in claim 1, wherein the one or more
25 characteristics measured by the flow element (50) comprises flow rate,
velocities, pressure, and temperature.