CA2351217C - An apparatus for supplying a therapeutic oxygen gas - Google Patents
An apparatus for supplying a therapeutic oxygen gas Download PDFInfo
- Publication number
- CA2351217C CA2351217C CA002351217A CA2351217A CA2351217C CA 2351217 C CA2351217 C CA 2351217C CA 002351217 A CA002351217 A CA 002351217A CA 2351217 A CA2351217 A CA 2351217A CA 2351217 C CA2351217 C CA 2351217C
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- CA
- Canada
- Prior art keywords
- valve
- respiration
- conduit
- pressure
- therapeutic gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/10—Preparation of respiratory gases or vapours
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/06—Respiratory or anaesthetic masks
- A61M16/0666—Nasal cannulas or tubing
- A61M16/0672—Nasal cannula assemblies for oxygen therapy
- A61M16/0677—Gas-saving devices therefor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
- A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
- A61M2016/0015—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors
- A61M2016/0018—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors electrical
- A61M2016/0021—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors electrical with a proportional output signal, e.g. from a thermistor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2202/00—Special media to be introduced, removed or treated
- A61M2202/02—Gases
- A61M2202/0208—Oxygen
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2230/00—Measuring parameters of the user
- A61M2230/40—Respiratory characteristics
- A61M2230/42—Rate
Abstract
The apparatus includes a cylinder for containing a pressurized therapeutic oxygen gas, a nasal cannula, adapted to be introduced into a nasal passage of a patient, and a conduit extending between the cylinder and the nasal cannula for directing the therapeutic oxygen gas to the nasal cannula from the cylinder. A pressure sensor is provided on the conduit for detecting the pressure in the conduit. A valve is provided, in the conduit, which allows and blocks the fluid communication between the cylinder and the nasal cannula. A controller controls the operation of the valve in synchronization with the respiration of a patient, based on the changes in the pressure detected by the pressure sensor. The volume of the oxygen therapeutic gas passing through the valve for each respiration is increased, compared with a normal respiration condition, when the respiratory frequency increases.
Description
- 1 ~
BACKGROUND OF THE INVENTION
1. Field of the Invention The invention relates to an apparatus for supplying a therapeutic oxygen gas.
BACKGROUND OF THE INVENTION
1. Field of the Invention The invention relates to an apparatus for supplying a therapeutic oxygen gas.
2. Description of the Related Art In treatmerits for respiratory system diseases such as pulmonary emphysema or chronic bronchitis, oxygen inhalation is known as one of the most effective treatments. In oxygen inhalation therapy, a therapeutic oxygen gas, such as oxygen gas or an oxygen enhanced gas which may be produced by separating nitrogen gas from air, is supplied to the patient with a therapeutic oxygen gas supplying apparatus.
Conventional therapeutic oxygen gas supplying apparatuses supply a therapeutic oxygen gas intermittently, in synchronization with the respiration of a patient, at a constant volume for each respiration.
The respiratory frequency, however, is not constant.
When the respiratory frequency is increased, in particular when tachypnea is presented, if the therapeutic oxygen gas supplying apparatus supplies the therapeutic oxygen gas at a constant volume for each respiration, dyspnea will result.
SUMMARY OF THE INVENTION
The invention is directed to solve the prior art problems, and to provide an apparatus for supplying a therapeutic oxygen gas improved to change the volume for each respiration in accordance with the respiratory frequency.
According to the invention, there is provided an apparatus for supplying a therapeutic oxygen gas. The apparatus comprises a cylinder for containing pressurized therapeutic oxygen gas, a nasal cannula, adapted to be introduced into a nasal passage of a patient, and a ~ 2 ~
conduit extending between the cylinder and the nasal cannula for directing the therapeutic oxygen gas to the nasal cannula from the cylinder. A pressure sensor is provided on the conduit for detecting the pressure in the conduit. A valve is provided on the conduit, which allows and blocks the fluid communication between the cylinder and the nasal cannula. A controller controls the operation of the valve in synchronization with the respiration of a patient based on the changes in the.
pressure detected by the pressure sensor. The volume of the therapeutic oxygen gas passing through the valve for each respixation is increased, compared with a normal respiration condition, when the respiratory frequency increases.
DESCRIPTION OF THE DRAWINGS
These and other objects and advantages and further description will now be discussed in connection with the drawings in which:
Figure 1 is a block diagram of a therapeutic oxygen gas supplying apparatus according to an embodiment of the invention;
Figure 2 is a flow chart showing an algorithm of determining the time period for opening the solenoid operated valve; and Figure 3 is graph which shows the volume of the therapeutic oxyge,n gas supplied to a patient, the volume increasing in steps according to an increase in respiratory frequency.
Description of the Preferred Embodiments With reference to Figure 1, a therapeutic oxygen gas supplying apparatus 10 according an embodiment of the invention supplies a therapeutic oxygen gas, pure oxygen gas or an oxygen enhanced gas, to a patient (not shown) from an oxygen gas cylinder 12 through a conduit 18 and a nasal cannula 16 attached to the face of the patient.
The conduit 18 comprises a flexible tube which is, at one of the ends, attached to a shut-off valve 14, connected to the oxygen cylinder 12, and, at the other end, to an inlet port 16a of the nasal cannula 16. The nasal cannula 16 provides means for introducing the therapeutic oxygen gas and includes a pair of cannula portions 16b which are adapted to be introduced into the nasal passages of the patient.
A pressure regulating valve 20 and an orifice 22 are provide on the conduit 18 downstream of the shut-off valve 14. Downstream of the orifice 22, a solenoid operated valve 24 is provided. The pressure regulating valve 20 and an orifice 22 regulate the pressure in the conduit 18 upstream of the solenoid operated valve 24 at a predetermined pressure. The solenoid operated valve 24 includes a solenoid 24a for moving the solenoid operated valve 24 between a first and a second position. At the first position, the solenoid operated valve 24 blocks the flow of the therapeutic oxygen gas, and at the second position, the solenoid operated valve allows the therapeutic oxygen gas to flow therethrough. A pressure sensor 26 is provided on the conduit 18 downstream of the solenoid operated valve 24. The pressure sensor 26 can be any kind of pressure sensor which provides an eleCtric signal representing the pressure in the conduit 18.
Preferably, the pressure sensor 26 comprises an electrostatic capacity type pressure sensor having a capacitor of which the capacitance changes in response to the changes in the pressure in the conduit 18.
The apparatus 10 further comprises a controller 30 for controlling the operation of the solenoid operated valve 24 in synchronization with the respiration of the patient. The controller 30 includes an A/D converter 32, a counter 34, a microcomputer 50, an input device 36, a solenoid driver 38 and a display 40. The microcomputer 50 includes CPU (central processing unit) 52, ROM (read-only memory) 54, RAM (random-access memory) 56, an input port 36 and an output ports 60, which are connected to each other through a bidirectional bus 62. The A/D
Conventional therapeutic oxygen gas supplying apparatuses supply a therapeutic oxygen gas intermittently, in synchronization with the respiration of a patient, at a constant volume for each respiration.
The respiratory frequency, however, is not constant.
When the respiratory frequency is increased, in particular when tachypnea is presented, if the therapeutic oxygen gas supplying apparatus supplies the therapeutic oxygen gas at a constant volume for each respiration, dyspnea will result.
SUMMARY OF THE INVENTION
The invention is directed to solve the prior art problems, and to provide an apparatus for supplying a therapeutic oxygen gas improved to change the volume for each respiration in accordance with the respiratory frequency.
According to the invention, there is provided an apparatus for supplying a therapeutic oxygen gas. The apparatus comprises a cylinder for containing pressurized therapeutic oxygen gas, a nasal cannula, adapted to be introduced into a nasal passage of a patient, and a ~ 2 ~
conduit extending between the cylinder and the nasal cannula for directing the therapeutic oxygen gas to the nasal cannula from the cylinder. A pressure sensor is provided on the conduit for detecting the pressure in the conduit. A valve is provided on the conduit, which allows and blocks the fluid communication between the cylinder and the nasal cannula. A controller controls the operation of the valve in synchronization with the respiration of a patient based on the changes in the.
pressure detected by the pressure sensor. The volume of the therapeutic oxygen gas passing through the valve for each respixation is increased, compared with a normal respiration condition, when the respiratory frequency increases.
DESCRIPTION OF THE DRAWINGS
These and other objects and advantages and further description will now be discussed in connection with the drawings in which:
Figure 1 is a block diagram of a therapeutic oxygen gas supplying apparatus according to an embodiment of the invention;
Figure 2 is a flow chart showing an algorithm of determining the time period for opening the solenoid operated valve; and Figure 3 is graph which shows the volume of the therapeutic oxyge,n gas supplied to a patient, the volume increasing in steps according to an increase in respiratory frequency.
Description of the Preferred Embodiments With reference to Figure 1, a therapeutic oxygen gas supplying apparatus 10 according an embodiment of the invention supplies a therapeutic oxygen gas, pure oxygen gas or an oxygen enhanced gas, to a patient (not shown) from an oxygen gas cylinder 12 through a conduit 18 and a nasal cannula 16 attached to the face of the patient.
The conduit 18 comprises a flexible tube which is, at one of the ends, attached to a shut-off valve 14, connected to the oxygen cylinder 12, and, at the other end, to an inlet port 16a of the nasal cannula 16. The nasal cannula 16 provides means for introducing the therapeutic oxygen gas and includes a pair of cannula portions 16b which are adapted to be introduced into the nasal passages of the patient.
A pressure regulating valve 20 and an orifice 22 are provide on the conduit 18 downstream of the shut-off valve 14. Downstream of the orifice 22, a solenoid operated valve 24 is provided. The pressure regulating valve 20 and an orifice 22 regulate the pressure in the conduit 18 upstream of the solenoid operated valve 24 at a predetermined pressure. The solenoid operated valve 24 includes a solenoid 24a for moving the solenoid operated valve 24 between a first and a second position. At the first position, the solenoid operated valve 24 blocks the flow of the therapeutic oxygen gas, and at the second position, the solenoid operated valve allows the therapeutic oxygen gas to flow therethrough. A pressure sensor 26 is provided on the conduit 18 downstream of the solenoid operated valve 24. The pressure sensor 26 can be any kind of pressure sensor which provides an eleCtric signal representing the pressure in the conduit 18.
Preferably, the pressure sensor 26 comprises an electrostatic capacity type pressure sensor having a capacitor of which the capacitance changes in response to the changes in the pressure in the conduit 18.
The apparatus 10 further comprises a controller 30 for controlling the operation of the solenoid operated valve 24 in synchronization with the respiration of the patient. The controller 30 includes an A/D converter 32, a counter 34, a microcomputer 50, an input device 36, a solenoid driver 38 and a display 40. The microcomputer 50 includes CPU (central processing unit) 52, ROM (read-only memory) 54, RAM (random-access memory) 56, an input port 36 and an output ports 60, which are connected to each other through a bidirectional bus 62. The A/D
converter 32 is connected to the pressure sensor 32 to receive the electric signal, preferably the capacitance, representing the pressure in the conduit 18. The A/D
converter 32 generates electric pulse to the counter 34, connected to the A/D converter 32. The counter 34 is connected to the input port 58 and provides it with a digital signal representing the number of the electric pulse from the A/D converter 32. The input device 36 may comprise keys, buttons or dials for setting parameters for controlling the apparatus 10. The display 40 may comprise liquid crystal display for indicating the parameters, set by the input device 36, and the operational condition of the apparatus 10.
The operational function of the embodiment will be described below.
The pressure sensor 26 presents an electric signal representing the pressure in the conduit 18. For example, if the pressure sensor 26 is an electrostatic capacity type pressure sensor, a capacitance proportional to the pressure in the conduit 18 is transmitted to the A/D converter 32. The A/D converter 32 generates electric pulses of which the number is proportional to the capacitance of the pressure sensor 26. The counter 34 counts the electric pulses from the A/D converter 32 and generates a digital signal corresponding to the number of the electric pulses. The microcomputer 50 determines the initiation of the respiration by monitoring the changes in pressure in the conduit 18 with the digital signal from the counter 34 as follows.
Respiration includes inhalation and expiration.
During inhalation, the pressure in the conduit 18 decreases. On the other hand, during expiration, the pressure increases. The ratio between the time periods of inhalation and expiration (I/E ratio) is generally 1/2. The microcomputer 50 differentiates the pressure in the conduit 18 thus obtained. The time when the differentiated pressure is minimum is determined as the initiation of a respiration.
When the microcomputer 50 detects the initiation of a respiration, the microcomputer 50 generates a valve open command to the solenoid driver 38. When the solenoid diver 38 receives the valve open command, the solenoid driver 38 energizes the solenoid 24a to move the solenoid operated valve 24 to the second position whereby the valve 24 opens to allow the oxygen therapeutic gas to flow therethrough. The microcomputer 50 generates the valve open command for a valve opening time long enough to provide the patient with a predetermined volume of the oxygen therapeutic gas prescribed by a doctor, as described below.
Figure 2 is a flow chart showing an algorithm of determining the time period for opening the solenoid operated valve 24. After the activation of the apparatus 10, in step 510, an initialization is carried out wherein the following parameters are input to the microcomputer 50 with the input device 36.
R,,: respiratory frequency when the respiration of the patient is normal condition (BPM (breaths par minute)) Ra: a first threshold value for respiratory frequency larger than R,(aPM) Rb: a second threshold value for respiratory frequency larger than Ra(BPM) Fo: flow rate of oxygen therapeutic gas -whi.ch may be prescribed by a doctor (m'/min) In step 10, time period ti(minutes) for opening the solenoid operated valve 24 is calculated by the flowing equation.
ti=Fo/Ct.R,fo...(1) where:
a: non-dimensional constant fo: flow rate of oxygen therapeutic gas through the solenoid operated valve 24 when the valve 24 is open under the predetermined pressure in the conduit 18 upstream of the valve 24 (m3/min) The non-dimensional constant a is an inverse of ratio of the time period of inhalation relative to the time period of one respiration, and it can be 3 since the z/E ratio is generally 1/2. If the I/E ratio is not 1/2, the non-dimensional constant a can be altered, accordingly.
The time period T thus obtained means a time period for opening the solenoid operated valve 24 sufficient for the volume of the oxygen therapeutic gas, which may be prescribed by a doctor, to flow through the valve 24 during inhalation of normal condition.
In steps S12 and S14, the initiation of respiration is determined by monitoring the changes in the pressure, as described above. zn step S16, the microcomputer 50 calculates the respiratory frequency R by measuring the time interval between initiations of sequential tow respirations. In step S18, the respiratory frequency R
is compared with the first threshold value R. which is larger than the respiratory frequency R. under the normal respiration condition. If R is equal to or smaller than R. ("No" at the step S18), then the respiration is determined as normal, and the time period z is decided, in step 22, as valve opening time T,õ for actually opening the solenoid operated valve 24. If R is larger than Ra ("Yes" at the step S18), then, in step S20, R is further compared with the second threshold value Rb. If R is equal to or smaller than Rb ("Yes" at the step S20), then, the respiration is determined as mild tachypnea, and Zxa is decided, in step 24, as the valve opening time T.o. Here "a" is a predetermined constant larger than 1, and can, for example, be 1.25. If R is larger than Rb ("No" at the step S20) then the respiration is determined as heavy tachypnea, and ixb is decided, in step 26, as ~ 7 ~
the valve opening time Tõa. Here b is a predetermined constant larger than "a", and can, for example, be 1.50.
The microcomputer generates a valve opening command to the solenoid driver 38 for the valve opening time Tõa.
Therefore, the volume of the oxygen therapeutic gas supplied to the patient for each respiration increases in steps according to the increase in the respiratory frequency, as shown in Figure 3. In Figure 3, võ
indicates the volume of the therapeutic oxygen gas supplied for each respiration under the normal respiration condition, V, indicates the volume when the respiratory frequency is above R,, and V. indicates the volume when the respiratory frequency is above Rb.
zt will also be understood by those skilled in the art that the forgoing description is a preferred embodiment of the disclosed device and that various changes and modifications may be made without departing from the spirit and scope of the invention.
converter 32 generates electric pulse to the counter 34, connected to the A/D converter 32. The counter 34 is connected to the input port 58 and provides it with a digital signal representing the number of the electric pulse from the A/D converter 32. The input device 36 may comprise keys, buttons or dials for setting parameters for controlling the apparatus 10. The display 40 may comprise liquid crystal display for indicating the parameters, set by the input device 36, and the operational condition of the apparatus 10.
The operational function of the embodiment will be described below.
The pressure sensor 26 presents an electric signal representing the pressure in the conduit 18. For example, if the pressure sensor 26 is an electrostatic capacity type pressure sensor, a capacitance proportional to the pressure in the conduit 18 is transmitted to the A/D converter 32. The A/D converter 32 generates electric pulses of which the number is proportional to the capacitance of the pressure sensor 26. The counter 34 counts the electric pulses from the A/D converter 32 and generates a digital signal corresponding to the number of the electric pulses. The microcomputer 50 determines the initiation of the respiration by monitoring the changes in pressure in the conduit 18 with the digital signal from the counter 34 as follows.
Respiration includes inhalation and expiration.
During inhalation, the pressure in the conduit 18 decreases. On the other hand, during expiration, the pressure increases. The ratio between the time periods of inhalation and expiration (I/E ratio) is generally 1/2. The microcomputer 50 differentiates the pressure in the conduit 18 thus obtained. The time when the differentiated pressure is minimum is determined as the initiation of a respiration.
When the microcomputer 50 detects the initiation of a respiration, the microcomputer 50 generates a valve open command to the solenoid driver 38. When the solenoid diver 38 receives the valve open command, the solenoid driver 38 energizes the solenoid 24a to move the solenoid operated valve 24 to the second position whereby the valve 24 opens to allow the oxygen therapeutic gas to flow therethrough. The microcomputer 50 generates the valve open command for a valve opening time long enough to provide the patient with a predetermined volume of the oxygen therapeutic gas prescribed by a doctor, as described below.
Figure 2 is a flow chart showing an algorithm of determining the time period for opening the solenoid operated valve 24. After the activation of the apparatus 10, in step 510, an initialization is carried out wherein the following parameters are input to the microcomputer 50 with the input device 36.
R,,: respiratory frequency when the respiration of the patient is normal condition (BPM (breaths par minute)) Ra: a first threshold value for respiratory frequency larger than R,(aPM) Rb: a second threshold value for respiratory frequency larger than Ra(BPM) Fo: flow rate of oxygen therapeutic gas -whi.ch may be prescribed by a doctor (m'/min) In step 10, time period ti(minutes) for opening the solenoid operated valve 24 is calculated by the flowing equation.
ti=Fo/Ct.R,fo...(1) where:
a: non-dimensional constant fo: flow rate of oxygen therapeutic gas through the solenoid operated valve 24 when the valve 24 is open under the predetermined pressure in the conduit 18 upstream of the valve 24 (m3/min) The non-dimensional constant a is an inverse of ratio of the time period of inhalation relative to the time period of one respiration, and it can be 3 since the z/E ratio is generally 1/2. If the I/E ratio is not 1/2, the non-dimensional constant a can be altered, accordingly.
The time period T thus obtained means a time period for opening the solenoid operated valve 24 sufficient for the volume of the oxygen therapeutic gas, which may be prescribed by a doctor, to flow through the valve 24 during inhalation of normal condition.
In steps S12 and S14, the initiation of respiration is determined by monitoring the changes in the pressure, as described above. zn step S16, the microcomputer 50 calculates the respiratory frequency R by measuring the time interval between initiations of sequential tow respirations. In step S18, the respiratory frequency R
is compared with the first threshold value R. which is larger than the respiratory frequency R. under the normal respiration condition. If R is equal to or smaller than R. ("No" at the step S18), then the respiration is determined as normal, and the time period z is decided, in step 22, as valve opening time T,õ for actually opening the solenoid operated valve 24. If R is larger than Ra ("Yes" at the step S18), then, in step S20, R is further compared with the second threshold value Rb. If R is equal to or smaller than Rb ("Yes" at the step S20), then, the respiration is determined as mild tachypnea, and Zxa is decided, in step 24, as the valve opening time T.o. Here "a" is a predetermined constant larger than 1, and can, for example, be 1.25. If R is larger than Rb ("No" at the step S20) then the respiration is determined as heavy tachypnea, and ixb is decided, in step 26, as ~ 7 ~
the valve opening time Tõa. Here b is a predetermined constant larger than "a", and can, for example, be 1.50.
The microcomputer generates a valve opening command to the solenoid driver 38 for the valve opening time Tõa.
Therefore, the volume of the oxygen therapeutic gas supplied to the patient for each respiration increases in steps according to the increase in the respiratory frequency, as shown in Figure 3. In Figure 3, võ
indicates the volume of the therapeutic oxygen gas supplied for each respiration under the normal respiration condition, V, indicates the volume when the respiratory frequency is above R,, and V. indicates the volume when the respiratory frequency is above Rb.
zt will also be understood by those skilled in the art that the forgoing description is a preferred embodiment of the disclosed device and that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (7)
1. An apparatus for supplying an oxygen therapeutic gas, comprising:
a nasal cannula adapted to be introduced into a nasal passage of a patient;
a conduit communicating with the nasal cannula and arranged to direct a pressurized oxygen therapeutic gas to the nasal cannula;
a pressure senor provided on the conduit, arranged to detect the pressure in the conduit;
a valve, provided on the conduit, arranged to allow and block a fluid communication to the nasal cannula;
a controller adapted to control the operation of the valve in synchronization with the respiration of a patient based on the changes in the pressure detected by the pressure sensor, to increase the volume of the oxygen therapeutic gas passing through the valve for each respiration, compared with a normal respiration condition, when the respiratory frequency increases, such that the volume of oxygen therapeutic gas supplied to the patient increases in steps according to the increase in the respiratory frequency, wherein the time period (T) for opening the valve is given by the formula T=F o/.alpha.R n f o wherein:
f o is the flow rate of oxygen therapeutic gas through the valve when the valve is open under a predetermined pressure In the conduit upstream of the valve;
R n is the respiratory frequency when the respiration of the patient is in normal condition;
F o is a predetermined flow rate of oxygen therapeutic gas; and .alpha. is a non-dimensional constant that is an inverse of the ratio of the time period of inhalation relative to the time period of one respiration.
a nasal cannula adapted to be introduced into a nasal passage of a patient;
a conduit communicating with the nasal cannula and arranged to direct a pressurized oxygen therapeutic gas to the nasal cannula;
a pressure senor provided on the conduit, arranged to detect the pressure in the conduit;
a valve, provided on the conduit, arranged to allow and block a fluid communication to the nasal cannula;
a controller adapted to control the operation of the valve in synchronization with the respiration of a patient based on the changes in the pressure detected by the pressure sensor, to increase the volume of the oxygen therapeutic gas passing through the valve for each respiration, compared with a normal respiration condition, when the respiratory frequency increases, such that the volume of oxygen therapeutic gas supplied to the patient increases in steps according to the increase in the respiratory frequency, wherein the time period (T) for opening the valve is given by the formula T=F o/.alpha.R n f o wherein:
f o is the flow rate of oxygen therapeutic gas through the valve when the valve is open under a predetermined pressure In the conduit upstream of the valve;
R n is the respiratory frequency when the respiration of the patient is in normal condition;
F o is a predetermined flow rate of oxygen therapeutic gas; and .alpha. is a non-dimensional constant that is an inverse of the ratio of the time period of inhalation relative to the time period of one respiration.
2. The apparatus according to claim 1, wherein the ratio of the time period of inhalation relative to the time period of respiration is 1:2, so that the non-dimensional constant a is 3.
3. The apparatus according to claim 1, wherein the controller compares the respiratory frequency with a threshold to increase the volume of the oxygen therapeutic gas for each respiration when the respiratory frequency is larger than the threshold.
4. The apparatus according to claim 1, wherein the valve is a solenoid operated valve having a solenoid, and the controller controls the solenoid to open the valve for a time period sufficient for a volume of the oxygen therapeutic gas to flow therethrough for each respiration.
5. The apparatus according to claim 1, wherein the pressure sensor is an electric capacitor-type pressure sensor having a capacitor of which the electrostatic capacitance represents the detected pressure.
6. The apparatus according to claim 1, wherein the controller determines, the initiation of each respiration by monitoring the changes in the pressure detected by the pressure sensor:
7. The apparatus according to claim 6, wherein the controller calculates the respiratory frequency by measuring the time interval between the initiations of sequential respirations.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002351217A CA2351217C (en) | 2001-06-19 | 2001-06-19 | An apparatus for supplying a therapeutic oxygen gas |
| US09/884,138 US6880556B2 (en) | 2001-06-19 | 2001-06-20 | Apparatus for supplying a therapeutic oxygen gas |
| EP01113681.9A EP1270035B1 (en) | 2001-06-19 | 2001-06-20 | An apparatus for supplying a therapeutic oxygen gas |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002351217A CA2351217C (en) | 2001-06-19 | 2001-06-19 | An apparatus for supplying a therapeutic oxygen gas |
| US09/884,138 US6880556B2 (en) | 2001-06-19 | 2001-06-20 | Apparatus for supplying a therapeutic oxygen gas |
| EP01113681.9A EP1270035B1 (en) | 2001-06-19 | 2001-06-20 | An apparatus for supplying a therapeutic oxygen gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2351217A1 CA2351217A1 (en) | 2002-12-19 |
| CA2351217C true CA2351217C (en) | 2008-12-02 |
Family
ID=27171570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002351217A Expired - Lifetime CA2351217C (en) | 2001-06-19 | 2001-06-19 | An apparatus for supplying a therapeutic oxygen gas |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US6880556B2 (en) |
| EP (1) | EP1270035B1 (en) |
| CA (1) | CA2351217C (en) |
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| US20050217668A1 (en) * | 2003-10-24 | 2005-10-06 | Pulmonox Technologies Corporation | System and elements for managing therapeutic gas administration to a spontaneously breathing non-ventilated patient |
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| US7533670B1 (en) | 2005-09-20 | 2009-05-19 | Breathe Technologies, Inc. | Systems, methods and apparatus for respiratory support of a patient |
| US7523752B2 (en) | 2005-09-21 | 2009-04-28 | Ino Therapeutics, Llc | System and method of administering a pharmaceutical gas to a patient |
| US8893717B2 (en) | 2005-09-21 | 2014-11-25 | Ino Therapeutics Llc | Systems and methods of administering a pharmaceutical gas to a patient |
| FR2896697B1 (en) * | 2006-02-01 | 2009-04-17 | Air Liquide | DEVICE FOR DELIVERING APPROPRIATE RESPIRATORY OXYGEN QUALITY |
| US8460223B2 (en) | 2006-03-15 | 2013-06-11 | Hill-Rom Services Pte. Ltd. | High frequency chest wall oscillation system |
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- 2001-06-19 CA CA002351217A patent/CA2351217C/en not_active Expired - Lifetime
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- 2001-06-20 US US09/884,138 patent/US6880556B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| US20020195106A1 (en) | 2002-12-26 |
| EP1270035A1 (en) | 2003-01-02 |
| US6880556B2 (en) | 2005-04-19 |
| CA2351217A1 (en) | 2002-12-19 |
| EP1270035B1 (en) | 2017-06-07 |
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