JP2000024109A - Device for helping respiration, its operating method and medical method for treating obstructive sleep apena syndrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a side-effect to be given to a patient by controlling gas pressure or the like so as to reach a required gas pressure (flow rate) just as humidity reaches a required humidity level in a device by which humidified air generated by means of a humidifier is supplied to the patient through a conduit. SOLUTION: A patient 1 receives a humidified and pressurized gas through a nose mask 2 connected to an inhalation conduit 3 which is extended from an exit 4 of a humidifying chamber 5 charged with water 6 and where a heating means is arranged in order to evade the condensing of the humidified gas in the conduit. The humidifying chamber 5 is provided with a high temp. conductive base part which is directly brought into contact with a heating plate 7 and air is supplied from a blower 15 having a speed-variable fan 21. The heating plate 7 and the blower 15 are controlled by an electronic controller 9 for inputting the output signals of a temp. sensor 11, a humidify sensor 12 and a heating plate temp. sensor 14 through a connector 13 and a setting signal by using a dial 19 in order to keep the humidity and the temp. of gas to be supplied to a required value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to health management devices, and particularly, but not exclusively, to obstructive sleep apnea (OSA).
The invention relates to a wet positive airway pressure (PAP) device for use in the treatment of cancer and a method of controlling such a device.

[0002]

BACKGROUND OF THE INVENTION OSA is a type of sleep dysfunction, which is estimated to affect at least only 5% of the population. The symptoms are that the muscles that keep the airway open during normal times relax, eventually crushing and obstructing the airway. The sleep pattern of a patient with OSA symptoms is characterized by repeating a series of actions such as snoring, dyspnea, lack of breathing, awakening, and returning to sleep. However, patients are often unaware that this pattern is occurring. Usually, OSA patients fall asleep or become hypersensitive during the day due to lack of good continuous sleep.

In treating OSA patients, a technique known as continuous positive airway pressure (CPAP) has been devised. CPAP devices using this technique typically consist of a gas supply (or blower) with a conduit connected to deliver pressurized gas to the patient via a nasal mask. The pressurized gas delivered to the patient effectively helps the muscles keep the patient's airway open, removing the typical OSA sleep pattern.

It is known that the use of this CPAP system has side effects such as dehydration of the airways and dehydration in the nasal cavity causing rhinitis (airway inflammation of the nasal cavity). This side effect is that patients will not want to respond to CPAP therapy,
This also means that the therapy itself may increase the resistance of the intranasal airways to high velocity airflow and reduce the pressure levels acting on the airways, thereby reducing the effectiveness of the therapy. Therefore, a wet CPAP system becomes important. For a modification of the standard CPAP system, see Respironics Inc.
No. 5,537,997 to U.S. Pat. In this refinement, a humidifier is incorporated into the CPAP system so that the patient receives the humidified gas.

[0005]

However, a simple combination of a known humidifier (in which gas passes through water vapor evaporating from the surface of a humidifying chamber on a heating plate) and a CPAP device, The benefits of wet CPAP therapy for patients are not maximized. This is due to the fact that it takes some time for the heating plate to warm up, and in some cases (especially when the device warms up) the patient receives a supply of unhumidified gas. It should be noted that the delicate tissues in the nasal swelling can be swelled after only a short period of non-humidified airflow, of the order of 10 minutes. It is therefore advantageous if the gas received by the patient is always humidified (up to the current capacity of the humidifier).

[0006] It is therefore an object of the present invention to provide at least some way to overcome the above disadvantages or to provide a respiratory assist device that gives the public at least some effective choices.

[0007]

SUMMARY OF THE INVENTION Accordingly, from a first aspect, the present invention is directed to a respiratory assist device adapted to deliver gas to a patient to assist the patient in breathing. Gas supply means including pressure regulating means adapted to supply gas with the resulting gas flow rate, and gas pressure sensing means for determining the pressure of the supplied gas and the resulting gas flow rate; Humidifying means for receiving the supplied gas before being transported to the patient, controllably humidifying the gas to a required humidity level, and a transport passage for flowing the humidified gas to the patient. Means, gas humidity detecting means for determining the humidity of gas supplied to the patient, and gas humidity and gas flow supplied from the gas humidity detecting means and the gas pressure detecting means. The humidity by controlling the gas supply means according to the information about the same time the gas pressure as to reach the required humidity consisting breathing assistance apparatus and a control means so as to reach the required pressure related.

In a second aspect, the present invention is directed to a gas supply means, a gas pressure regulating means adapted to supply gas at a required gas pressure and a resulting gas flow rate, and a required humidity level. Gas humidifying means capable of humidifying the gas in a controllable manner, a transport means, and a predetermined required pressure and humidity value are stored. A) Starting the operation of the gas humidifying means and Humidifying the gas from the gas supply means; b) detecting the pressure of the gas; c) detecting the humidity of the gas; d) adjusting the gas supply pressure to the patient to reach the required humidity level. Control means being programmed to perform each step of simultaneously causing said gas pressure and the resulting gas flow to reach said required pressure and the resulting gas flow. It consists of an operating method of the provided breathing assist device.

Further, from a third aspect, the present invention provides a gas supply means, a gas pressure regulating means adapted to supply gas at a required gas pressure and a resulting gas flow rate, and a required humidity level. Gas humidifying means capable of humidifying the gas in a controllable manner, conveying means for flowing the humidified gas to the patient, and storing predetermined required pressure and humidity values, and Activating the humidifying means to humidify the gas from the gas supply means; b) detecting the pressure of the gas; c) detecting the humidity of the gas; d) adjusting the gas supply pressure to the patient. Performing each step of causing the gas pressure and the resulting gas flow to reach the required pressure and the resulting gas flow at about the same time that the required humidity level is reached. A method for treating obstructive sleep apnea using a respiratory assist device having programmed control means.

[0010]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, there is shown a wet continuous positive airway pressure (CPAP) system in which a patient 1 is humidified pressurized gas via a nasal mask 2 connected to a humidified gas transport passage or inhalation conduit 3. Receive. However, the invention is not limited to the transfer of CPAP gas, but other types of gas delivery systems, such as variable positive airway pressure (VPAP), bilevel positive airway pressure (BiVPAP) type gases, etc. It should be understood that it can also be applied to transportation systems. The intake conduit 3 is connected to an outlet 4 of a humidification chamber 5 containing a predetermined volume of water 6. The intake conduit 3 may include heating means or heating wires (not shown). The heating wire heats the walls of the intake conduit to ensure a constant humidity profile along the intake conduit, thus reducing condensation of the humidified gas in the intake conduit. The humidifying chamber 5 is preferably formed of a plastic material, and may have a base having a high thermal conductivity (for example, an aluminum base) that directly contacts the heating plate 7 of the humidifier 8. The humidifier 8 includes a control means or an electronic control device 9.
The control device 9 may include a microprocessor-based control device that executes computer software instructions stored in an attached memory.

The control unit 9 receives input from an input source such as a user input device or dial 10. The user of the device can set a predetermined required value (preset value) of, for example, the humidity or temperature of the gas supplied to the patient 1 via the input device. The controller 9 may also receive inputs from other input sources, such as temperature, humidity and / or flow rate sensors 11 and 12 via a connector 13, and an input from a hotplate temperature sensor 14. Dial 1
Depending on the value of the humidity or temperature set by the user via 0 and other setting values, the control device 9 controls when (or to what level) the heating plate 7 to heat the water 6 in the humidification chamber 5.
Determines whether to energize. A predetermined volume of water 6 in the humidification chamber 5
Is heated, the steam begins to fill the humidification chamber volume above the water surface and exits the humidification chamber 5 with the gas flow (eg, air) provided by the gas supply or blower 15 into the humidification chamber inlet 16. pass. Note that a relationship between the gas humidity in the humidification chamber 5 and the temperature of the heating plate 7 can be obtained. Thus, the temperature of the hotplate can be used in an algorithm or look-up table to determine the humidity of the gas (thus, the hotplate temperature acts as a gas humidity indicator, and these two terms are interchangeable herein). Used as a possible term). The gas exhaled from the patient's mouth is directly discharged to the surrounding atmosphere of FIG. Note that while the preferred embodiment of the present invention uses hotplate temperature to represent humidity, any suitable humidity sensor could be used instead.

The blower 15 is provided with a variable pressure regulating means or a variable speed fan 21 which draws air or other gas through the inlet 17 of the blower to form a final gas flow. The speed of the variable speed fan 21 is controlled by another control means or electronic control according to an input from the control device 9 and a predetermined value (preset value) of the flow rate or pressure set by the user using the dial 19 or the fan speed. Controlled by device 18 (the function of controller 18 can also be performed by controller 9) (fan speed, gas flow rate and gas pressure, as described above for the relationship between hot plate and humidity). , So that these three terms are used interchangeably herein).

A modifiable preferred embodiment of the wet CPAP system is shown in FIG. In FIG. 2, the humidifier is a blower 15
The same conduit 3 and nasal mask 2 are integrated into the system
Only the main elements connected to the patient via the In this embodiment, only one control device 9 is required. This wet CPAP system is both "warm up"
Any of the foregoing, including mode embodiments, can be substituted. All reference numbers common to FIG. 1 represent similar features of the present invention.

During "warm-up" (the period when the hotplate has not reached its set or required temperature), the manner in which the hotplate and / or blower fan is energized can be controlled. Two preferred examples of control methodologies used during this period are described below. First Preferred "Warm-Up" Mode Embodiment In use, the user of the wet CPAP system determines a pressure setpoint (or setpoint) _Pset of the gas delivered to the patient 1 by the blower 15. This set value is sent to the control device 18 by the dial 19. Further, the user determines a set value (or required value) T _set of the temperature of the heating plate 7. This set value is input from the dial 10 to the control device 9. The dial for setting temperature user input may be labeled “humidity” for convenience. Next, the control device 9 sends the current gas pressure P via the sensor 14 to the current temperature T _actual of the heating plate 7.
_actual is determined via the speed sensor 20, for example. Note that it may take 30 minutes for the gas to reach its set humidity level, depending on environmental conditions, gas flow rates, and obstructions in the patient's airways (eg, sites of inflammation). The current pressure value may be determined by a pressure or flow sensor in the blower 15, in the humidification chamber 5, or in the conduit connecting the system. Alternatively, the speed of the fan 21 can be used to represent the gas pressure as described above (the speed detected by the speed sensor 20 or the command speed issued from the control device 18 to the fan may be the actual speed). Available as a fan speed).

Next, the control device 9 controls the temperature (representing the humidity).
The humidity and pressure of the airflow to the patient 1 are controlled using the set value and the actual value of the pressure (or fan speed). The pressure and temperature (humidity) of the gas delivered to the patient will eventually reach the values set by the user, respectively, but the humidified gas saturated with the maximum possible water vapor (within the currently existing limits of the humidifier) To ensure that it is always supplied to the patient,
The controller 9 controls the speed of the fan 21 based on the humidity of the gas (or synchronized with the temperature of the heating plate 7). As an example (see FIGS. 3 and 4), the following table shows the detected temperature (initial temperature) and set temperature (or required temperature), and the (relative) pressure value (equivalent to fan speed) at the start of the system. ing.

[0016]

[Table 1] The controller 9 then determines the required pressure change (ΔP) and the required temperature change (ΔT) to obtain the required set pressure and temperature of the system, respectively. In this example

[0017]

[Table 2] Next, the control device 9 determines the required average pressure increase rate with respect to the temperature by dividing ΔP by ΔT. In this example, the calculation result is 10 cmH ₂ O / 30 ° C. or (1
/ 3) cmH ₂ O / ° C. Therefore, in this example, every time the temperature of the heating plate 7 rises by 1 ° C., the control device 9 increases the speed of the fan 21 to reduce the pressure to (１ ／) cmH ₂ O.
Is given to the control device 18 so as to ascend. In this way, (the time t _s shown i.e. in Figures 3 and 4) at the same time to each of the set point temperature and pressure of the gas delivered to the patient arrives. Preferably, the hotplate is a wet CPA
When the P system is activated, it is energized and its temperature is gradually raised to a set temperature (as shown in FIG. 4), and when the set temperature is reached, the controller 9 continuously deactivates the heating plate appropriately. And re-energize to maintain the set temperature. The controller 9 continuously monitors the temperature of the hotplate until the set temperature is reached and continuously determines the updated required average rate of increase value, or initially determines it over the entire warm-up period. Requested average growth rate can be used.
In this way, the patient will always receive the humidified gas. This is because at the start of operation, a small amount of water vapor in the humidifying chamber 5 is conveyed by a light or slow air flow, while the heating plate reaches the required set temperature (thus, a large amount of water vapor is generated in the humidifying chamber. Because the blower is controlled to generate a larger volume flow of gas. Second Preferred "Warm-Up" Mode Embodiment It should be noted that all integers shown and described in connection with FIGS. 1 and 2 relate to this second embodiment.

As with the preferred embodiment described above, the wet CPAP system according to this preferred embodiment has a "warm-up" function. The warm-up function determines how to increase the motor speed of the fan 21 (and thus the flow rate or pressure of the conveyed gas) over time after system operation. Therefore, it is desirable that the pressure increase as the humidity increases and the flow rate increase so that the desired set pressure is reached when the humidity output of the device reaches its equilibrium or required level.

The controller 9 uses closed-loop control of the temperature of the heating plate 7 to reach the desired level of humidity as quickly as possible. Through some trials, the hotplate temperature itself (as used in the previous example) is not necessarily a very good indicator of the humidity transported to the patient, and the temperature of the water in the humidification chamber 5 Has been found to be a better humidity index. It should be noted that the temperature rise of the water is very slow compared to the heating plate 7, since water has a very poor property in terms of energy transfer. Therefore, if the fan speed is controlled based solely on the heating plate temperature, the flow rate may suddenly become excessive during the warm-up cycle. Although the water temperature is not measured directly (it is not practical, if not impossible to include a temperature sensor inside the humidification chamber 5), as described below, how the temperature of the water in the humidification chamber 5 is It is possible to reasonably and accurately estimate whether it will rise.

The specific heat capacity of water represents the amount of heat (or energy) required to raise the unit mass of water by one degree. When the operation of the wet CPAP system according to this preferred embodiment of the present invention is started, the controller 9 measures the actual temperature of the hot plate 7 (assuming that it is equal to the water temperature in a steady state) and receives a user's instruction (for example, button, switch, etc.). An input of a set (or required) temperature of the hotplate (or via a user interface including a dial) is received. The controller 9 then determines the temperature change required to reach the set (or required) humidity value. Preferably, the control device 9 sets the temperature of the heating plate 7 to 90 ° in a steady state when the water temperature in the humidifying
Utilize 90% of the temperature change required to reach%.
Using the required temperature change value (or the percentage thereof), the mass of the water in the humidifying chamber (the humidifying chamber 5 is 400 ml,
g of water), the amount of energy required to raise the water temperature to the set temperature can be calculated.

Further, the control device 9 controls, for example, the duty cycle of the element (time _on / (time _on + time)
By controlling e _off )), the urging action of the heating plate 7 is controlled, so that the amount of energy transferred from the heating plate 7 to water can be known. For example, a hot plate element with a 60% duty cycle and 85 watts transfers 51 joules of energy per second to water. Energy is removed from water by two dominant means: conduction and convection.

The conduction losses are displaced through the humidification chamber walls and conduits. During warm-up and in steady state, the amount of energy loss due to conduction losses is directly proportional to the temperature gradient between water and the environment (air temperature). Knowing the temperature of the water and the ambient temperature (e.g. by ambient air temperature sensor 22 or more preferably by estimating a fixed temperature, e.g., 20 [deg.] C), the conduction energy loss _Econd can be estimated during warm-up. . Although the water temperature is not directly measured in this embodiment, from some trials, the difference between the average water temperature and the ambient temperature is about 68% of the difference between the hot plate temperature and the ambient temperature.
I know that That is, (T _water −T
_{ambient) = 0.68 × (T heater} -T ambi ent). This approximation of the water temperature involves sampling the hotplate temperature and water temperature over the warm-up period, dividing the water temperature by the hotplate temperature, and dividing the resulting value over the warm-up period (from start of operation to gas (Until supplied at the required humidity).

The energy loss due to the convection is caused by the air flow crossing the water in the humidification chamber 5. For the average flow of CPAP users, the flow rate (Q) expressed in liters per minute is given per minute (RPM) for a given limit (for example, assuming a standard conduit of 6 feet in length). And the loss due to convection is almost directly proportional to the flow rate. Determine appropriate proportional constants from experiments and substitute them into the following equation. Therefore, the energy loss E _conv due to convection can be calculated. Thus, at any time, it is possible to calculate the net amount of energy E _{tr ans} moved to the water in the humidifier chamber 5.

When using the system (see FIG. 5), the warm-up algorithm according to the second preferred embodiment of the present invention operates as follows. A. Ignore losses Upon operation of the CPAP system, the controller 9 reads the required or set fan speed and temperature (representing gas pressure and humidity) from the user input devices 19 and 10, respectively, and reads the current temperature T _start of the heating plate 7.
The water temperature at this time is about 90% of the temperature of the heating plate 7. The fan 21 is energized at a low initial speed of, for example, 3000 RPM to form an initial pressure and the resulting flow rate, for example, 16 liters per minute (in QAP systems, the flow rate (Q) expressed in Q liters per minute) It is directly proportional to the fan motor speed (υ) expressed in RPM and therefore Q
= Υ / 186.2. ). Next, the energy amount E _{required required} to raise the temperature of the water of mass (m) in the humidifying chamber 5 to the set temperature by the temperature (ΔT = (T _required −T _start ) × 0.9) is as follows. (Where k _s is the specific heat capacity of water).

E _{total required} = k _s × m × ΔT = 4.
19 × 103 × 0.4 × (T _required −T _start ) ×
0.9 The controller 9 then applies (eg, applied to the heating element) such that the predetermined required hot plate temperature (eg, about 60 ° C.) is achieved as quickly as possible and with or without overshoot. Closed-loop control system that adjusts the duty cycle of the applied voltage).

2. At predetermined time intervals (t _f ), for example, every 30 seconds, the net energy (E _{transferred) transferred} from the heating element or heating plate 7 (power rating _Pr watts, duty cycle D (%)) to water during this interval. ) Is calculated. This value is then subtracted from the total energy required to heat the water to the set temperature to obtain the energy required to reach the set temperature from this point.

[0027]

(Equation 1) More generally, for each subsequent iteration (i),

[0028]

(Equation 2) 3. Using the net energy transferred to the water during the last 30 seconds, or rather the average transfer rate P _transfer of the net energy, and the energy value required to reach the newly calculated set temperature, the time to reach the set temperature t _s can be calculated as follows. _{P transfer} = E transperred / 30 (W) and t _s = E _needed / P _transfer Accordingly, initially

[0029]

(Equation 3) Estimated time to be updated for subsequent iterations

[0030]

(Equation 4) Can be calculated as follows:

[0031]

(Equation 5) B. Including Loss However, as mentioned above, conduction and convection losses must be used to account for the amount of energy lost to water in the humidification chamber. The conduction and convection losses can be calculated as follows.

E _conv = k _conv × Q and Q = k _Q × υ Therefore, E _conv = k _conv × k _Q × υ = (1 / 186.2) × 5.79 × υ (for 30 seconds) _cond = k _cond x (T _water- T _ambient ) = 10.83 x 0.68 x (T _heater -20) = 7.4 x T _heater -148 (joule, 30 seconds during warm-up) Add to _needed and subtract from E _transferred . Therefore,

[0033]

(Equation 6)

[0034]

(Equation 7) Therefore,

[0035]

(Equation 8) Or

[0036]

(Equation 9) 4. Using the time calculated here and the difference between the set speed and the actual speed, the average increase rate (γ) of the speed can be calculated.

[0037]

(Equation 10) The actual speed of the motor is adjusted to form the calculated acceleration. 5. These steps 2 to 4 are repeated every 30 seconds (the value of E _{total requied} is reduced by the net energy transferred to the water E _{transferred in the} last 30 seconds), thereby the net energy transfer rate to the humidification chamber As time varies, the average required increment of time to reach set point and motor speed is continuously calculated. This process is repeated until the time to reach the set temperature t _s becomes zero and the set speed is reached, at which time the temperature of the water in the humidifying chamber 5 should have reached the required or set temperature.

In the above algorithm, the humidification chamber is 400
Note that it is assumed to hold ml water
I want to be. When a smaller amount of water has less time to reach the set temperature
Time, thereby increasing the duty cycle of the heating element
Set more quickly to a lower level, and as a result
Net energy transfer rate (E_net= E_transferred-E
_cond-E_conv) Is lower, so the humidification chamber is 400m
Warm up when holding less than l water
The time gets longer. Under the experimental conditions, the wet CPAP device
The warm-up time ranges from 15 minutes to 2 depending on the operating conditions.
It has changed within 5 minutes.

It should be noted that in the preferred embodiment described above, the fan speed is essentially controlled depending on the water temperature which is determined indirectly. However, as described above, it is desirable to control the pressure of the gas being transported to the patient, depending on the humidity of that gas. In the above system (such as a hose about 6 feet long) pressure (P) and flow (Q) can be approximated by the following equations:

P = 8.836 × 10 ⁻³ Q ² Therefore, the pressure increases with the square of the fan speed. But,
Using the above equation, the fan speed can be used as an index of the pressure, and the gas pressure can be calculated from the fan speed. Similarly, for example, determine the mass of water that evaporates in one second,
By dividing that value by the current flow rate, an equation can be formed that relates temperature to humidity. Thus, while the preferred embodiment according to the present invention has been described with reference to fan speed and water temperature, the CPAP system of the present invention controls the gas pressure to deliver only fully humidified gas to the patient. More surely. Also, the known relationship between fan speed, pressure, temperature and humidity can be used in step 1 above so that the user can input the required pressure and humidity values directly into the device.
The controller 9 can then calculate the required fan speed and temperature values and perform the remaining steps sequentially.

The graph shown in FIG. 5 shows that the temperature of the hotplate reaches its set point relatively quickly, and that the control system described in connection with the second embodiment provides fan speed (FIG. 5). RPM) increases linearly and more gradually as the water temperature increases. Other considerations When the hot plate temperature is close to the set temperature at the start of the CPAP system (for example, the patient was using the device,
The controller may stop synchronizing and maintaining the temperature and pressure when the temperature and pressure increase (if the device is temporarily turned off and the device is switched off or the device is put into standby mode). . In this case, the controller may first determine whether the actual hotplate temperature is about 75% or more of its set value, or within, for example, 5% of its set value. If so, the speed of the fan 21 is controlled to linearly increase from a somewhat lower initial value to a required set value for a predetermined period (for example, 15 minutes).
Alternatively, the controller determines whether the actual hotplate temperature is within a certain range, for example, within about 10 ° C. of the required set temperature value, and then determines the fan speed for a predetermined period of time. The speed of the fan 21 can be controlled so as to reach the set value.

The alternative fan speed control process described above means that when the hotplate is already warm, the hotplate will soon reach its set temperature (before the patient goes to sleep), thus humidifying the gas within the capabilities of the humidifier. This is necessary due to the fact that the maximum fan speed should be reduced for a set period so that the gas can be humidified and / or the user can go to sleep before the maximum flow is reached. The predetermined period may be set by the manufacturer before the device is sold, or the value may be made controllable by the user, for example by adding a further dial so that it can be entered into the control device 9. You may.

Also preferably, the controller monitors the calculated net energy transfer value E _net and determines that value (eg, 3
When found to be zero or negative (zero second period), it is determined that the warm-up should have been completed (starting with less energy than the calculated value because the water in the humidification chamber was less than expected). Due to the fact that it was not necessary from time to time). In this state, the fan speed is automatically increased to the set fan speed. Another feature is to monitor the warm-up period, so if the warm-up continues after approximately 25 minutes, the fan speed is automatically increased to the set fan speed as if the warm-up period had ended. can do.

Buttons can be additionally provided in the input section of the control device 9. When the user presses this button,
The above-described fixed period in which the fan speed increases linearly can be started. Once the warm-up is complete (when the temperature and pressure have reached their respective required values), the user knows that they cannot go to sleep, and thus the user needs to temporarily reduce the fan speed. In this case, the user simply presses the above button, which causes another linear fan speed increase effect which increases to the required set speed at a predetermined low speed (even if the water temperature is already at the required set temperature). Even if it was).

Thus, the present invention provides a wet breathing system that provides beneficial humidified gas to a patient both during periods when the humidifier is warming up and during periods when the humidifier is actually operating (at its set temperature). Provide an auxiliary system. Further, the humidity of the gas delivered to the patient is maintained throughout both of these periods within the limits of the humidifier's ability to humidify the gas beneficial to the patient. This means that unhumidified or poorly humidified gas flow to the patient can cause harmful swelling of the nasal airways, even for a short period of time (eg, 10 minutes), and is even greater if delivered through the oral cavity. The present invention is extremely beneficial to the patient because it can cause discomfort.

[Brief description of the drawings]

FIG. 1 is a block diagram of a wet continuous positive airway pressure (CPAP) system according to a preferred embodiment of the present invention.

FIG. 2 shows a wet CPA according to another preferred embodiment of the present invention.
It is a block diagram of a P system.

FIG. 3 is a graph showing an example of a relationship between air pressure (estimated by fan speed) and time of the wet CPAP system according to the first preferred embodiment;

FIG. 4 shows the humidity (actually, the temperature of the heating plate) and the second value of the present invention.
4 is a graph (corresponding to FIG. 3) showing an example of a relationship with time in a wet CPAP system according to a preferred embodiment of the present invention.

FIG. 5 is a graph showing the relationship between experimentally obtained data and many parameters of a wet CPAP system according to a second preferred embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Patient 2 ... Nasal mask 3 ... Inhalation conduit 5 ... Humidifying chamber 6 ... Water 7 ... Heat plate 8 ... Heating device 9 ... Control device 10 ... Dial 15 ... Blower 21 ... Fan

Claims (30)

[Claims] 1. A respiratory assist device adapted to deliver gas to a patient for assisting the patient in breathing, wherein the gas is supplied at a required gas pressure and a resulting gas flow rate. Gas supply means including pressure adjusting means, gas pressure sensing means for determining the pressure of the supplied gas and the resulting gas flow rate, and receiving the supplied gas before being transported to the patient Humidifying means capable of controllably humidifying the gas to a required humidity level, conveying path means for conveying the humidified gas to the patient, and determining the humidity of the gas supplied to the patient. Gas humidity detection means, gas humidity and gas pressure supplied from the gas humidity detection means and the gas pressure detection means, and the resulting gas flow rate. The gas pressure and the resulting gas flow rate reach the required pressure and the resulting gas flow rate at about the same time that the humidity reaches the required humidity by controlling the gas supply means in accordance with the information A respiratory assistance device provided with control means for controlling the respiration. 2. A humidifying chamber means in which the humidifying means receives a predetermined volume of water, and an energizable heating means for heating the predetermined volume of water to generate steam in the humidifying chamber means. 2. The respiratory assist device according to claim 1, further comprising: humidifying the gas by passing water vapor in the humidifying chamber means. 3. 3. The gas pressure adjusting means includes a variable speed fan, and the gas pressure detecting means detects a speed of the fan and includes a speed sensor for supplying a flow rate indicator of the gas flow to the control means. The respiratory assist device according to claim 1 or 2, wherein: 4. The temperature of the energizable heating means detected by the gas humidity detecting means comprises a part of the control means and includes a means for detecting the temperature of the energizable heating means. The respiratory assist device according to claim 2 or 3, wherein the humidity of the gas is estimated based on the following. 5. The gas / humidity detecting means constitutes a part of the control means and includes means for detecting a temperature of the energizable heating means, wherein a temperature of the predetermined volume of water in the humidifying means is determined. Estimating the humidity of the gas based on the calculated value of and adding an amount dependent on the amount of energy added to the predetermined volume of water to the detected temperature of the energizable heating means, The respiratory assist device according to claim 2 or 3, wherein the calculated value is determined. 6. The control means is a programmable processor storing a program, the program being executed on the processor, i) being moved to the gas humidification means to reach the required humidity level. Ii) determining the current energy transfer rate to the humidifying means; and iii) converting the total energy determined in step (i) to the energy transfer determined in step (ii). Calculating the time to reach the required humidity level by dividing by a rate; iv) the ratio of the pressure of the gas transported from the gas supply device to the required pressure by controlling the gas pressure regulator. Performing each step of making the ratio of the humidity of the gas relative to the required humidity level substantially equal to that of the required humidity level, 6. A breath as claimed in any one of the preceding claims, wherein steps (i) to (iv) are repeated until the humidification is approximately at the required humidity level with the required pressure and the resulting flow rate. Auxiliary equipment. 7. In the step (ii), the energy transfer rate is determined by determining an energy transfer amount to the gas humidifier within a predetermined set period, and determining the determined energy transfer amount in the set period. The respiratory assist device according to claim 6, wherein the estimation is performed by dividing. 8. Adding a first amount equal to the estimated convective energy loss at the respiratory assist device and a second amount equal to the estimated conduction energy loss at the respiratory assist device to the determined amount. The respiratory assist device according to claim 7, wherein the time until the required humidity level is reached is calculated in step (iii). 9. A method according to claim 1, wherein a first amount equal to the estimated convective energy loss in the respiratory assist device and a second amount equal to the estimated conducted energy loss in the respiratory assist device are applied to the gas humidifier. The respiratory assist device according to claim 6 or 8, wherein a time until the required humidity level is reached in step (iii) is calculated by subtracting from the energy transfer amount. 10. The method according to claim 1, wherein the predetermined setting period is about 30.
The respiratory assist device according to any one of claims 7 to 9, wherein the second is seconds. 11. The method according to claim 6, wherein said step (i) includes calculating a required initial energy amount and subtracting an energy amount sequentially moving to said humidifying means in a preceding period to be integrated. The respiratory assistance device according to claim 1. 12. The gas conveying passage means includes a passage heating means therein, the passage heating means being controllably biased by the control means to reduce condensation along the length of the conveying passage means. The respiratory assist device according to any one of claims 1 to 11, wherein: 13. In response to an input from an operator, independent of the humidity of the gas over a period determined by the operator input, to achieve a predetermined pressure profile of the supplied gas. The respiratory assist device according to any one of claims 1 to 12, further comprising a variable user input unit that controls the control unit to control the gas supply unit. 14. The respiratory assist device of claim 13, wherein the predetermined pressure profile is a linear slope from an initial low pressure for the supplied gas to a final pressure equal to the required pressure. 15. Gas supply means, gas pressure adjusting means adapted to supply gas at a required gas pressure and a resulting gas flow rate, and humidifying said gas controllably to a required humidity level. A method for operating a respiratory assist device, comprising: gas humidifying means capable of performing the above-mentioned steps; transport means for flowing humidified gas to the patient; and control means for storing a predetermined required pressure and humidity values. Starting the operation of the gas humidifier to humidify the gas from the gas supply means; b) detecting the pressure of the gas; c) detecting the humidity of the gas; d) controlling the gas supply pressure to the patient. The gas pressure and the resulting gas flow reach the required pressure and the resulting gas flow at about the same time as reaching the required humidity level. Method of operating a breathing assistance apparatus including. 16. A humidifying chamber means in which the gas humidifying means receives a predetermined volume of water, and an energizable heating for heating the predetermined volume of water to generate water vapor in the humidifying chamber means. 16. The operating method according to claim 15, further comprising means for humidifying the gas by passing water vapor in the humidifying chamber means. 17. The gas pressure adjusting means comprises a variable speed fan, and the step of sensing the pressure of the gas and the resulting gas flow rate senses the speed of the fan and directs the control means to the control means. 17. The operating method according to claim 15 or 16, comprising providing a pressure and a flow index of the gas flow. 18. The method of claim 16, wherein detecting the humidity of the gas comprises estimating the humidity based on the temperature of the energizable heating means. 19. The method of claim 19, wherein detecting the humidity of the gas comprises estimating the humidity based on a calculated value of a temperature of the predetermined volume of water in the gas humidifier. A calculated value for the temperature is determined by sensing the temperature and adding an amount dependent on the amount of energy added to the predetermined volume of water to the sensed temperature of the energizable heating means. An operating method according to claim 16. 20. The step (d) comprises: 1) determining the total amount of energy to be transferred to the gas humidifier in order for the humidity of the gas to reach the required humidity level; 3) The time to reach the required humidity level by dividing the total energy determined in step (1) by the energy transfer rate determined in step (2). 4) controlling the gas pressure regulating device so that the ratio of the pressure of the gas transported from the gas supply device to the required pressure is substantially equal to the ratio of the humidity of the gas to the required humidity level. The steps until the supplied gas is substantially humidified to the required humidity level at the required pressure and the resulting flow rate. The operating method according to any one of 1) (4) from claim 15 to repeat until 19. 21. The step (2) comprising: determining an amount of energy transfer to the gas humidifier within a predetermined set period, and dividing the determined energy transfer amount by the set period. 21. A method according to claim 20, comprising: 22. A first amount equal to an estimated convective energy loss in the respiratory assist device and a second amount equal to a conductive energy loss estimated in the respiratory assist device are added to the determined amount. 22. The operating method according to claim 21, wherein the time until the required humidity level is reached is calculated in step (3). 23. A method for applying a first amount equal to the estimated convective energy loss in the respiratory assist device and a second amount equal to the estimated conduction energy loss in the respiratory assist device to the gas humidifying means. 23. The operating method according to claim 20, wherein the time required to reach the required humidity level in step (3) is calculated by subtracting from the energy transfer amount. 24. The method according to claim 24, wherein the predetermined setting period is about 30.
An operating method according to any one of claims 21 to 23, wherein the second is seconds. 25. The method according to claim 20, wherein said step (1) includes the steps of calculating a required initial energy amount and subtracting an energy amount sequentially added to said gas humidifying means in a preceding period to be integrated. The operation method according to any one of claims 1 to 4. 26. The transfer passage means includes a passage heating means therein, the passage heat means being controllably biased by the control means to reduce condensation along the length of the transfer passage means. 26. The operating method according to any one of 15 to 25. 27. A system comprising: a variable user input means responsive to an input from an operator, independent of the humidity of the gas for a period determined by the input of the operator.
27. A method according to any one of claims 15 to 26, wherein the control means controls the gas supply means to achieve a predetermined pressure profile of the supplied gas. 28. The method of claim 27, wherein the predetermined pressure profile is a linear ramp from an initial low pressure for the supplied gas to a final pressure equal to the required pressure. 29. Gas supply means, gas pressure adjustment means adapted to supply gas at a required gas pressure and the resulting gas flow rate, and humidifying said gas controllably to a required humidity level. Humidifying means, a conveying means for flowing humidified gas to the patient, and a control means for storing predetermined required pressure and humidity values. In the method for treating respiratory disease, a) starting the operation of the gas humidifier to humidify the gas from the gas supply means, b) detecting the pressure of the gas, c) detecting the humidity of the gas d. The gas pressure and the resulting gas flow rate at approximately the same time as controlling the gas supply pressure to the patient to reach the required humidity level; The method of treating obstructive sleep apnea provided with the respective stages so as to reach. 30. The step (d) comprises: I) determining the total amount of energy to be transferred to the gas humidifier in order for the humidity of the gas to reach the required humidity level; III) the time to reach the required humidity level by dividing the total energy determined in step (I) by the energy transfer rate determined in step (II) IV) controlling the gas pressure regulator so that the ratio of the pressure of the gas transported from the gas supply to the required pressure is approximately equal to the ratio of the humidity of the gas to the required humidity level. Until the supplied gas is substantially humidified to the required humidity level at the required pressure and the resulting flow rate. The method of treating obstructive sleep apnea according to claim 29 which is adapted to repeat said from step (I) (IV).