# US 11,433,198 B2 · Methods and apparatus for flow therapy

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,433,198 B2
- Document ID: US11433198B2
- Status: Granted
- Kind: B2
- Application number: 15/310,746
- Filed: 2015-05-15
- Published: 2017-03-30
- Granted: 2022-09-06
- Earliest claimed: 2014-05-16
- Assignees: Fisher & Paykel Healthcare Limited
- Applicants: Fisher & Paykel Healthcare Limited
- Inventors: Craig Karl White; Alicia Jerram Hunter Evans; Callum James Thomas Spence
- Web page: https://patentgrep.com/patent/US11433198B2

## CPC

- A61M 16/0069: {the speed thereof being controlled by respiratory parameters, e.g. by inhalation}
- A61B 5/01: Measuring temperature of body parts {; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue} (clinical contact thermometers G01K13/20)
- A61B 5/036: {by means introduced into body tracts (A61B5/032 and A61B5/035 take precedence)}
- A61B 5/08: Measuring devices for evaluating the respiratory organs
- A61B 5/087: Measuring breath flow
- A61B 5/6819: {Nose}
- A61M 16/0057: {Pumps therefor}
- A61M 16/024: {including calculation means, e.g. using a processor}
- A61M 16/0672: {Nasal cannula assemblies for oxygen therapy}
- A61M 16/109: {the humidifying liquid or the beneficial agent}
- A61M 16/1095: {in the connecting tubes}
- A61M 16/16: Devices to humidify the respiration air {(A61M16/1045 takes precedence)}
- A61M 16/161: {with means for measuring the humidity}
- A61M 2016/0021: {with a proportional output signal, e.g. from a thermistor}
- A61M 2016/0027: {pressure meter}
- A61M 2016/0033: {electrical}
- A61M 2016/0039: {in the inspiratory circuit}
- A61M 2016/0042: {in the expiratory circuit}
- A61M 2205/3334: Measuring or controlling the flow rate
- A61M 2205/3368: Temperature
- A61M 2205/502: User interfaces, e.g. screens or keyboards
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A method of estimating respiratory demand of a patient being administered flow therapy can include: administering a gas flow rate to the patient through both nostrils using a flow therapy apparatus with a patient interface for each nostril, measuring a parameter associated with that nostril, the parameter being one or more of: respiratory demand of that nostril, indicative of respiratory demand of that nostril, or a parameter from which respiratory demand of that nostril can be derived, determining respiratory demand (or parameter indicative of respiratory demand) for the patient from the nostril parameter for each nostril.

## Claims

### Claim 1

A method of estimating a respiratory demand of a patient being administered flow therapy comprising:
using a controller of a flow therapy apparatus:
controlling a flow generator of a flow therapy apparatus so that the flow generator administers gas to the patient through both nostrils using a non-sealing patient interface, wherein the gas administered to the patient is at a predetermined gas flow rate;
for each nostril, measuring a nostril parameter associated with that nostril using one or more sensors of the flow therapy apparatus, the nostril parameter being one or more of:
a respiratory demand of that nostril,
a parameter indicative of the respiratory demand of that nostril, or
a parameter from which the respiratory demand of that nostril is configured to be derived;
wherein the nostril parameter associated with each nostril is a pressure of a nasal passage for that nostril, or a pressure of a conduit leading to the nasal passage of that nostril, or both; and
calculating the respiratory demand of the patient from the nostril parameter associated with each nostril using a relationship between the nostril parameter associated with each nostril and the respiratory demand of the patient, wherein the respiratory demand of the patient is the gas flow rate required by the patient during breathing,
wherein the respiratory demand is calculated by:
combining the pressure of the nasal passage for each nostril, and using the relationship to determine an offset flow rate or a respiratory demand flow rate for the patient using the combined pressure of the nasal passage for each nostril, the relationship being stored in the controller, or
using the relationship, determining an offset flow rate or a respiratory demand flow rate for each nostril using the pressure of the nasal passage for each nostril and combining the offset flow rate or nasal respiratory demand flow rate for each nostril to provide the offset flow rate or respiratory demand flow rate for the patient.

### Claim 2 (depends on 1)

A method according to claim 1 wherein the respiratory demand of the patient is:
an inspiratory demand, and/or
an expiratory demand.

### Claim 3 (depends on 1)

A method according to claim 1 wherein the relationship is one or more of:
a look up table,
a mathematical relationship, or
a graph,
wherein the relationship correlates the offset flow rate or respiratory demand to the pressure of the nasal passage for each nostril or for the patient.

### Claim 4 (depends on 3)

A method according to claim 3 wherein the relationship comprises the mathematical relationship that is:
Q
offset
=
SQR
⁡
(
ABS
⁡
(
P
T
)
R
nasal
)
wherein
Qoffset is the offset flow rate for the respective nasal passage at a point in time and is calculated using said mathematical relationship,
PT is a terminal pressure in, at, near, or proximate an outlet of a respective nasal prong of the non-sealing patient interface or in, at, near, or proximate the respective nasal passage of the patient—at a point in time, and
Rnasal is a nasal resistance to flow of the respective nasal passage.

### Claim 5 (depends on 4)

A method according to claim 4 wherein:
for a non-laminar flow condition, the mathematical relationship is determined using the following equation:
R
nasal
=
P
trans
-
P
char
Q
offset
2
wherein
Ptrans is a pressure at an inspiration/expiration transition of breathing,
Pchar is a system characteristic pressure when Ptrans is being measured, wherein Pchar is zero or close to zero when measured at the nasal passage or nasal prongs,
and wherein for a laminar flow condition, the mathematical relationship is determined using the following equation:
R
nasal
=
P
trans
-
P
char
Q
offset
wherein Pchar=0 if the nostril parameter associated with each nostril is the pressure of the nasal passage for that nostril.

### Claim 6 (depends on 3)

A method according to claim 3 wherein the mathematical relationship is formed from an electrical analogy of the patient and is:
I=V/R
wherein
I is a current in the electrical analogy and corresponds to the offset flow rate for each nostril or the patient,
V is voltage in the electrical analogy and corresponds to the pressure of the nasal passage for each nostril, and
R is a resistance in the electrical analogy and corresponds to a nasal resistance to flow.

### Claim 7 (depends on 1)

A method according to claim 1 wherein:
a gas flow rate required to be supplied through both nostrils, or
a gas flow rate to be required through each nasal prong of the non-sealing patient interface to meet a respiratory demand of each nasal passage or of the patient, is configured to be determined using one or more of the following equations:
I
M
=
I
P
⁢
⁢
1
+
I
P
⁢
⁢
2
I
P
⁢
⁢
1
=
V
M
-
V
N
⁢
⁢
1
R
P
⁢
⁢
1
I
P
⁢
⁢
2
=
V
M
-
V
N
⁢
⁢
2
R
P
⁢
⁢
2
I
L
⁢
⁢
1
=
V
N
⁢
⁢
1
R
N
⁢
⁢
1
I
L
⁢
⁢
2
=
V
N
⁢
⁢
2
R
N
⁢
⁢
2
I
L
⁢
⁢
1
=
I
P
⁢
⁢
1
+
I
N
⁢
⁢
1
I
L
⁢
⁢
2
=
I
P
⁢
⁢
2
+
I
N
⁢
⁢
2
f
⁡
(
I
P
⁢
⁢
1
)
=
AI
P
⁢
⁢
1
2
+
BI
P
⁢
⁢
1
=
R
P
⁢
⁢
1
R
P
⁢
⁢
2
=
CI
P
⁢
⁢
2
2
=
DI
P
⁢
⁢
2
R
N
⁢
⁢
1
=
EI
L
⁢
⁢
1
2
+
FI
L
⁢
⁢
1
R
N
⁢
⁢
2
=
GI
L
⁢
⁢
2
2
+
HI
L
⁢
⁢
2
wherein
VM is a voltage of a manifold of the non-sealing patient interface, which corresponds to a pressure in the manifold or a system pressure (Psys),
Vn1 and Vn2 are nasal passage voltages for first and second nasal passages, which correspond to a pressure of the first and second nasal passages,
IM is a manifold current, which corresponds to a flow rate in the manifold or a system flow rate,
In1 and In2 are nasal passage current for the first and second nasal passages, which correspond to the respiratory demand flow rates for the first and second nasal passages,
IP1 and IP2 are prong currents for the first and second nasal passages, which correspond to the flow rates for the first and second nasal passages,
IL1 and IL2 are respective leakage currents, which correspond to the respective offset flow rates for the first and second nasal passages,
RP1 and RP2 are prong electrical resistances for the first and second nasal passages, which correspond to resistances to flow for the first and second nasal passages, and
RN1 and RN2 are respective leakage electrical resistances, which correspond to the respective offset resistances to flow for the first and second nasal passages.

### Claim 8 (depends on 1)

A method according to claim 1 further comprising displaying on a display the respiratory demand of the patient determined from the nostril parameter associated with each nostril.

### Claim 9 (depends on 1)

A method according to claim 1 further comprising manually or automatically controlling the flow therapy based on the respiratory demand of the patient determined from the nostril parameter associated with each nostril.

### Claim 10

A flow therapy system comprising:
a non-sealing patient interface, and
a flow therapy apparatus comprising:
a flow generator,
one or more sensors, and
a controller configured to:
control the flow generator to administer gas at a gas flow rate to the patient through both nostrils using the non-sealing patient interface,
for each nostril, measure from the one or more sensors a nostril parameter associated with that nostril, the nostril parameter being one or more of:
a respiratory demand of that nostril,
a parameter indicative of the respiratory demand of that nostril, or
a parameter from which the respiratory demand of that nostril is configured to be derived,
wherein the nostril parameter associated with each nostril is a pressure of a nasal passage for that nostril, or a pressure of a conduit leading to the nasal passage of that nostril, or both;
calculate a respiratory demand of the patient from the nostril parameter associated with each nostril using a relationship between the nostril parameter associated with each nostril and the respiratory demand of the patient, wherein the respiratory demand of the patient is the gas flow rate required by the patient during breathing,
wherein the respiratory demand is calculated by:
combining the pressure of the nasal passage for each nostril, and using the relationship to determine an offset flow rate or a respiratory demand flow rate for the patient using the combined pressure of the nasal passage for each nostril, or
using the relationship, determining an offset flow rate or a respiratory demand flow rate for each nostril using the pressure of the nasal passage for each nostril and combining the offset flow rate or nasal respiratory demand flow rate for each nostril to provide the offset flow rate or respiratory demand flow rate for the patient.

### Claim 11 (depends on 10)

A system according to claim 10 wherein the respiratory demand of the patient is:
an inspiratory demand, and/or
an expiratory demand.

### Claim 12 (depends on 10)

A system according to claim 10 wherein the relationship is one or more of:
a look up table,
a mathematical relationship, or
a graph,
wherein the relationship correlates the offset flow rate to the pressure of the nasal passage for each nostril or for the patient.

### Claim 13 (depends on 12)

A system according to claim 12 wherein the relationship comprises the mathematical relationship that is:
Q
offset
=
SQR
⁡
(
ABS
⁡
(
P
T
)
R
nasal
)
wherein
Qoffset is the offset flow rate for the respective nasal passage at a point in time and is calculated using said mathematical relationship,
PT is a terminal pressure in, at, near, or proximate an outlet of a respective nasal prong of the non-sealing patient interface or in, at, near, or proximate the respective nasal passage of the patient—at a point in time, and
Rnasal is a nasal resistance to flow of the respective nasal passage.

### Claim 14 (depends on 13)

A system according to claim 13 wherein:
for a non-laminar flow condition, the mathematical relationship is determined using the following equation:
R
nasal
=
P
trans
-
P
char
Q
offset
2
wherein
Ptrans is a pressure at an inspiration/expiration transition of breathing,
Pchar is a system characteristic pressure when Ptrans is being measured,
wherein Pchar is zero or close to zero when measured at the nasal passage or nasal prongs,
and wherein for a laminar flow condition, the mathematical relationship is determined using the following equation:
R
nasal
=
P
trans
-
P
char
Q
offset
wherein Pchar=0 if the nostril parameter associated with each nostril is the pressure of the nasal passage for that nostril.

### Claim 15 (depends on 12)

A system according to claim 12 wherein the relationship comprises the mathematical relationship that is formed from an electrical analogy of the patient and is:
I=V/R
wherein
I is a current in the electrical analogy and corresponds to the offset flow rate for each nostril or the patient,
V is voltage in the electrical analogy and corresponds to the pressure of the nasal passage for each nostril, and
R is a resistance in the electrical analogy and corresponds to a nasal resistance to flow.

### Claim 16 (depends on 10)

A system according to claim 10 wherein:
a gas flow rate required to be supplied through both nostrils, or
a gas flow rate to be required through each nasal prong of the non-sealing patient interface to meet a respiratory demand of each nasal passage or of the patient, is configured to be determined using one or more of the following equations:
I
M
=
I
P
⁢
⁢
1
+
I
P
⁢
⁢
2
I
P
⁢
⁢
1
=
V
M
-
V
N
⁢
⁢
1
R
P
⁢
⁢
1
I
P
⁢
⁢
2
=
V
M
-
V
N
⁢
⁢
2
R
P
⁢
⁢
2
I
L
⁢
⁢
1
=
V
N
⁢
⁢
1
R
N
⁢
⁢
1
I
L
⁢
⁢
2
=
V
N
⁢
⁢
2
R
N
⁢
⁢
2
I
L
⁢
⁢
1
=
I
P
⁢
⁢
1
+
I
N
⁢
⁢
1
I
L
⁢
⁢
2
=
I
P
⁢
⁢
2
+
I
N
⁢
⁢
2
f
⁡
(
I
P
⁢
⁢
1
)
=
AI
P
⁢
⁢
1
2
+
BI
P
⁢
⁢
1
=
R
P
⁢
⁢
1
R
P
⁢
⁢
2
=
CI
P
⁢
⁢
2
2
=
DI
P
⁢
⁢
2
R
N
⁢
⁢
1
=
EI
L
⁢
⁢
1
2
+
FI
L
⁢
⁢
1
R
N
⁢
⁢
2
=
GI
L
⁢
⁢
2
2
+
HI
L
⁢
⁢
2
wherein
VM is a voltage of a manifold of the non-sealing patient interface, which corresponds to a pressure in the manifold or a system pressure (Psys),
Vn1 and are nasal passage voltages for first and second nasal passages, which correspond to a pressure of the first and second nasal passages,
IM a manifold current, which corresponds to a flow rate in the manifold or a system flow rate,
In1 and In2 are nasal passage current for the first and second nasal passages, which correspond to the respiratory demand flow rates for the first and second nasal passages,
IP1 and IP2 are prong currents for the first and second nasal passages, which correspond to the flow rates for the first and second nasal passages,
IL1 and IL2 are respective leakage currents, which correspond to the respective offset flow rates for the first and second nasal passages,
RP1 and RP2 are prong electrical resistances for the first and second nasal passages, which correspond to resistances to flow for the first and second nasal passages, and
RN1 and RN2 are respective leakage electrical resistances, which correspond to the respective offset resistances to flow for the first and second nasal passages.

### Claim 17 (depends on 10)

A system according to claim 10 further comprising the controller being configured to display on a display of the apparatus the respiratory demand of the patient determined from the nostril parameter associated with each nostril.

### Claim 18 (depends on 10)

A system according to claim 10 further comprising the controller controlling flow therapy based on the respiratory demand of the patient determined from the nostril parameter associated with each nostril.

### Claim 19

A respiratory support system comprising:
a non-sealing patient interface, and
a respiratory support apparatus comprising:
a flow generator,
one or more sensors, and
a controller configured to:
control the flow generator to administer gas at a gas flow rate to the patient through both nostrils using the non-sealing patient interface,
for each nostril, measure from the one or more sensors a nostril parameter associated with that nostril, the nostril parameter being one or more of:
a respiratory demand of that nostril,
a parameter indicative of the respiratory demand of that nostril, or
a parameter from which the respiratory demand of that nostril is configured to be derived,
wherein the nostril parameter associated with each nostril is a pressure of a nasal passage for that nostril, or a pressure of a conduit leading to the nasal passage of that nostril, or both;
calculate a respiratory demand of the patient from the nostril parameter associated with each nostril using a relationship between the nostril parameter associated with each nostril and the respiratory demand of the patient, wherein the respiratory demand of the patient is the gas flow rate required by the patient during breathing,
wherein the respiratory demand is calculated by:
combining the pressure of the nasal passage for each nostril, and using the relationship to determine an offset flow rate or a respiratory demand flow rate for the patient using the combined pressure of the nasal passage for each nostril, the relationship being stored in the controller, or
using the relationship, determining an offset flow rate or a respiratory demand flow rate for each nostril using the pressure of the nasal passage for each nostril and combining the offset flow rate or nasal respiratory demand flow rate for each nostril to provide the offset flow rate or respiratory demand flow rate for the patient.