Systems and methods for monitoring and displaying respiratory information
Various embodiments of the present disclosure provide systems, methods and devices for respiratory support. As one example, a ventilation system is disclosed that includes a graphical display, a processor and a computer readable medium. The computer readable medium is communicably coupled to the processor and includes instructions executable by the processor to receive a measured pressure value, and receive a net flow value. The instructions are further executable to calculate a patient effort value based on a relationship between patient effort, the measured pressure value and the net flow value; and to plot the patient effort value to the graphical display.
1. A ventilation system, the ventilation system comprising:
a graphical display;
a processor communicably coupled to a computer readable medium, wherein the computer readable medium includes instructions executable by the processor to:
receive a measured pressure value;
receive a net flow value;
calculate a patient effort value based on a relationship between the measured pressure value, the net flow value, and an estimated normalized prediction error, wherein the estimated normalized prediction error is based at least in part on a current estimated value of a parameter vector; and
plot the patient effort value to the graphical display.
2. The system of claim 1 , wherein the patient effort value is an estimate of actual patient effort.
3. The system of claim 1 , wherein the patient effort value is a first derivative of the actual patient effort.
4. The system of claim 1 , wherein the patient effort value is a filtered patient effort.
5. The system of claim 1 , wherein the instructions are further executable by the processor to:
calculate a mean time between breaths based on the patient effort value; and
display the mean time between breaths to the graphical display.
6. The system of claim 1 , wherein the instructions are further executable by the processor to:
identify a peak breathing effort based on the patient effort value; and
display the peak breathing effort to the graphical display.
7. The system of claim 1 , wherein the instructions are further executable by the processor to:
identify a peak effort for a particular breath based on one or more patient effort values calculated during the particular breath; and
display the peak effort for the particular breath to the graphical display.
8. The system of claim 1 , wherein the instructions are further executable by the processor to:
calculate a duration of last inspiration based on the patient effort value; and
display the duration of last inspiration to the graphical display.
9. The system of claim 1 , wherein the instructions are further executable by the processor to:
calculate a duration of last expiration based on the patient effort value; and
display the duration of last expiration to the graphical display.
10. The ventilation system of claim 1 , wherein the patient effort value is further based on a combination of one or more intermediate values calculated using the measured pressure value and the net flow value, the one or more intermediate values selected from:
a filtered pressure value and a regression vector.
11. The ventilation system of claim 1 , wherein the relationship is a parameterized system input to output relationship.
12. The method of claim 11 , wherein the parameterized system input to output relationship is the regression form: z=Θφ+φ d , wherein z is a filtered pressure value, Θ is a current estimated value of a parameter vector, φ is at least apart of regression vector, and φ d is a filtered patient effort.
13. The method of claim 11 , wherein the parameterized system input to output relationship is derived from a transfer function.
14. The ventilation system of claim 13 , wherein the transfer function is derived from the model:
[
p
.
Y
p
.
L
]
=
[
-
1
C
T
R
P
1
C
T
R
P
1
C
L
R
P
-
1
C
L
R
P
]
[
p
Y
p
L
]
+
[
1
C
T
1
C
T
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1
C
T
0
0
0
]
[
q
AIR
q
O
2
q
E
]
+
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0
-
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T
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C
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[
p
.
P
q
Tleak
q
Pleak
]
wherein p y is a value for a wye gas pressure, p L is a value of a pressure in a patient's lungs, {dot over (p)} y is a value for a first derivative of a wye gas pressure, {dot over (p)} L is a value for a first derivative of pressure in the patient's lungs, C T is a value for a tubing compliance, C L , is a value for a lung compliance, R P is a value for a patient resistance, q air is a value for an inlet flow of air, q 02 is a value for an inlet flow of oxygen, q E is a value for an outlet gas flow, q Tleak is a value for gas flow associated with tubing leakage, q Pleak is a value for gas flow associated with leakage in the patient, and {dot over (p)} P is a value for the derivative of patient effort.
15. A method for providing graphical respiratory feedback, the method comprising:
providing a graphical display;
measuring a pressure and providing a measured pressure;
measuring an inlet flow and an outlet flow, and providing a measured net flow;
using a relationship between a first value related to the measured pressure, a second value related to the measured net flow and an estimated normalized prediction error, wherein the estimated normalized prediction error is based at least in part on a current estimated value of a parameter vector, to calculate an estimate of patient effort from the measured pressure and measured net flow; and
repeatedly displaying the estimate of patient effort as a function of time via the graphical display.
16. The method of claim 15 , wherein the estimate of patient effort is an estimate of actual patient effort for an associated time instant.
17. The method of claim 15 , wherein the estimate of patient effort is an estimate of a first derivative of the actual patient effort for an associated time instant.
18. The method of claim 15 , wherein the estimate of patient effort is a filtered actual patient effort.
19. The method of claim 15 , wherein the method further comprises:
calculating various ventilation characteristics based on the estimate of patient effort, wherein the various ventilation characteristics are selected from: a mean time between breaths, a peak breathing effort, a peak effort for a particular breath, a duration of last inspiration, a duration of last expiration, an average duration of inspiration, and an average duration of expiration.
20. The method of claim 15 , wherein the method further comprises:
graphically displaying various ventilation characteristics based on the estimate of patient effort, wherein the various ventilation characteristics are selected from: a mean time between breaths, a peak breathing effort, a peak effort for a particular breath, a duration of last inspiration, a duration of last expiration, an average duration of inspiration, and an average duration of expiration.
21. The method of claim 15 , wherein the relationship is defined by a parameterized system input to output relationship in the regression form z=Θ T φ+φ d , and wherein the input to output relationship is derived from a transfer function, wherein z is a filtered pressure value, Θ is a current estimated value of a parameter vector, φ is at least a part of regression vector, and φ d is a filtered patient effort.
22. The method of claim 21 wherein the transfer function is derived from a model:
[
p
.
Y
p
.
L
]
=
[
-
1
C
T
R
P
1
C
T
R
P
1
C
L
R
P
-
1
C
L
R
P
]
[
p
Y
p
L
]
+
[
1
C
T
1
C
T
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1
C
T
0
0
0
]
[
q
AIR
q
O
2
q
E
]
+
[
0
-
1
C
T
0
1
0
-
1
C
T
]
[
p
.
P
q
Tleak
q
Pleak
]
wherein p y is a value for a wye gas pressure, p L is a value of a pressure in a patient's lungs, {dot over (p)} y is a value for a first derivative of a wye gas pressure, {dot over (p)} L is a value for a first derivative of pressure in the patient's lungs, C T is a value for a tubing compliance, C L is a value for a lung compliance, R P is a value for a patient resistance, q air is a value for an inlet flow of air, q 02 is a value for an inlet flow of oxygen, q E is a value for an outlet gas flow, q Tleak is a value for gas flow associated with tubing leakage, q Pleak is a value for gas flow associated with leakage in the patient, and {dot over (p)} P is a value for the derivative of patient effort.
23. A ventilation system, the ventilation system comprising:
a gas inlet;
a gas outlet;
a tube coupling the gas inlet and the gas outlet;
a pressure sensor, wherein the pressure sensor is operable to provide a measured pressure value indicating a pressure in the tube;
a first flow sensor, wherein the first flow sensor is operable to provide an inlet flow value indicating a flow associated with the gas inlet;
a second flow sensor, wherein the second flow sensor is operable to provide an outlet flow value indicating a flow associated with the gas outlet;
a graphical display; and
a processor communicably coupled to a computer readable medium, wherein the computer readable medium includes instructions executable by the processor to:
receive a measured pressure value;
receive a net flow value;
calculate a patient effort value based on a relationship between patient effort, an estimated normalized prediction error, wherein the estimated normalized prediction error is based at least in part on a current estimated value of a parameter vector, the measured pressure value, and the net flow value;
calculate a gas delivery metric that varies as a first function of the patient effort value;
determine an inhalation phase based on the patient effort value; and
plot the patient effort value to the graphical display.