FR2779965A1 - Humidifier apparatus for sleep apnea treatment - Google Patents

Abstract

A breathing assistance apparatus comprises: (1) a gas supply including a gas pressure regulator for supplying gas at a required pressure with a resulting flow rate; (2) a gas pressure sensor for determining the pressure of the gas and therefore the resulting gases flow rate; (3) a humidifier for receiving and controllably humidifying the gases before delivery to the patient; (4) a transportation pathway (3) between the humidfier and the patient; (5) a gas humidity sensor; and (6) a controller (9) which controls the gas supply in response to gas humidity and gas pressure information so that the gas pressure and flow rate reach the required values at about the same time as the required humidity is reached. An Independent claim is included for a method of operating the breathing apparatus which comprises: (1) initiating the gas humidfier to humidify the gases form the gas supply; (2) sensing the gas pressure; (3) sensing the humidity of the gases; and (4) controlling the pressure at which the gases are supplied to the patient.

Description

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  BREATHING ASSISTANCE DEVICE AND IMPLEMENTATION METHOD

ARTWORK

  The present invention relates to a care device and in particular, although not only, a breathing aid device of the humidified positive pressure device type of the respiratory tract used in the treatment of apnea

  obstructive sleep and a method of controlling such a device.

  Obstructive sleep apnea is a sleeping sickness that affects what is estimated to be less than 5% of the population in which the muscles that normally keep the airways open, free them and ultimately crush them, ensuring the tightness of respiratory tracts. The sleep profile of an obstructive sleep apnea patient is characterized by repeated sequences of snoring, difficulty breathing, no breathing, waking with a start and then returning to sleep. Often the patient is not informed about the appearance of this profile. The first 5 people with obstructive sleep apnea usually experience drowsiness

  and irritability during the day due to the lack of good continuous sleep.

  In an effort to treat patients with obstructive sleep apnea, a technique known as continuous positive airway pressure has been devised. A continuous positive airway pressurization device consists of a gas supply (or blower) having a conduit connected to a pressurized gas supply to a patient, usually through a nasal mask. The pressurized air sent to the patient effectively helps the muscles to keep the patient's airways open, eliminating the

  sleep profile typical of obstructive sleep apnea.

  The use of a continuous positive airway pressure system is known to have side effects such as dehydration of the airways and passages of the nose which can lead to rhinitis (inflammation of the passages of the nose). Side effects mean that the patient is less likely to comply with his continuous positive airway pressure therapy and that the therapy itself may cause increased nasal resistance in response to a high, degrading airflow lc level of pressure applied to the respiratory tract and thus reducing the effectiveness of therapy. In

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  therefore, a continuous humidified positive airway pressure system would be an improvement. An improvement to the standard continuous positive airway pressure system is described in US Patent 5,537,997 assigned to Respironics Inc. in which a humidifier is incorporated into the continuous positive airway pressure system so that the patient

receives humidified gases.

  However, a simple combination of a well-known humidifier (in which gases are sent through water vapor rising from the surface of the water in a water humidification chamber to the top of a hot plate) and a continuous positive airway pressure device will not maximize patient benefit from humidified continuous positive airway pressure therapy. This is due to the fact that the heating plate takes some time to heat up so that the patient will, on certain occasions (especially during the warming up of the device), be supplied with gases which are not humidified. It will be noted that the sensitive tissues of the nasal passage may be caused to swell after receiving a flow of unhumidified gas for as little as 10 minutes. Consequently, an advantage would be that the gases received by the patient are always humidified (by the present or existing capacity of

humidifier) at any time.

  It is therefore an object of the present invention to provide a breathing aid device which will at least somehow overcome the

  disadvantages above or that will provide the public with a useful choice.

  Consequently, in a first aspect, the present invention consists of a breathing aid device adapted to supply gases to a patient to aid said breathing of the patient, comprising: gas supply means, comprising pressure regulation means suitable for supplying gases at a pressure required with a resulting gas flow rate, - gas pressure detection means for determining the pressure of said gases supplied and consequently the flow rate resulting from the gases,

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  - humidification means which receive and humidify said supplied gases before sending them to said patient, said humidification means being able to humidify said gases in a controlled manner to a required humidity level, - means forming a transport path which channel said humidified gases towards said patient, - gas humidity detection means for determining the humidity of the gases supplied to said patient, and - control means which in response to information concerning the humidity of the gases and the gas flow, supplied by said gas humidity detecting means and said gas pressure detecting means, control the gas supply means so that the gas pressure reaches the pressure

  required almost at the same time as the required humidity level is reached.

  In a second aspect, the present invention consists of a method of actuating a breathing aid device, the breathing aid device 1 5 comprising gas supply means, means of regulation of the pressure of the gases suitable for supplying gases at a pressure required with a resulting gas flow, gas humidification means capable of humidifying the gases in a controlled manner to a required humidity level, means transport and control means storing predetermined required pressure and humidity values, and programmed to perform the steps consisting in: a) triggering the gas humidification means to humidify the gases coming from the gas supply means , b) detecting the gas pressure, c) detecting the humidity of the gases, and d) adjusting the pressure at which the gases are supplied to said patient so that the gas pressure and the flow rate result both reach the required pressure and flow

  resulting substantially at the same time that the required humidity level is reached.

  In a third aspect, the present invention consists of a method for treating obstructive sleep apnea using a breathing aid device comprising gas supply means, gas pressure regulation means. adapted to supply gas at a pressure required with a gas flow

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  resulting, gas humidification means capable of controlled humidification of the gases to a required humidity level, transport means and control means memorizing the predetermined required pressure and humidity values, and programmed to execute the steps consisting in: a) triggering the gas humidification means for humidifying the gases coming from the gas supply means, b) detecting the gas pressure, c) detecting the humidity of the gases, and d ) adjusting the pressure at which the gases are supplied to said patient so that the gas pressure and the resulting flow reach the required pressure and the flow

  resulting substantially at the same time that the required humidity level is reached.

  A preferred form of the present invention will now be described with reference to the accompanying drawings, in which: - Figure 1 is a block diagram of a humidified continuous positive pressure system of the respiratory tract according to a preferred embodiment of the present invention, - Figure 2 is a block diagram of a humidified continuous positive pressure system of the respiratory tract according to another preferred embodiment of the present invention, - Figure 3 is a graph of given air pressure as an example (approached by a fan speed) as a function of time for the humidified continuous positive pressurization system of the respiratory tract according to the first preferred embodiment of the present invention, - Figure 4 is a graph given as an example ( corresponding to Figure 3) of 2 5 humidity (actually the temperature of the hot plate) depending on the time for the humidified continuous positive airway pressure system according to the second preferred embodiment of the present invention, and - Figure 5 is a graph of the data collected experimentally as a function of time for several parameters of the air system humidified continuous positive airway pressure according to the second preferred embodiment

of the present invention.

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  Referring to Figure 1, a humidified continuous positive pressurization system of the respiratory tract is shown in which a patient 1 receives humidified and pressurized gases through a nasal mask 2 connected to a transport path of humidified gases or a inspiration line 3. It should be understood that the present invention, however, is not limited to the supply of continuous positive pressurization gas to the respiratory tract but may also be applied to other types of delivery systems gases such as variable positive airway pressure systems and two-level positive airway pressure systems. The inspiration pipe 3 is connected to the outlet 4 of a humidification chamber 5 which contains a volume of water 6. The inspiration pipe 3 can contain heating means or heating wires (not shown) ) which heat the walls of the duct to ensure a constant humidity profile along the duct and therefore reduce the condensation of humidified gases in the duct. The humidification chamber 5 is preferably formed from a plastic material and can have a thermally very conductive base (for example a base in

  aluminum) which is in direct contact with a heating plate 7 of the humidifier 8.

  The humidifier 8 is provided with control means or with an electronic control 9 which may include a microprocessor-based control executing

  computer software instructions stored in associated memory.

  The control 9 receives inputs from sources such as input means or a dial for user 10, through which a user of the device can, for example, establish a predetermined required value (preset value) for humidity or the temperature of the gases supplied to patient 1. The control can also receive inputs from other sources, for example temperature, humidity and / or flow velocity detectors 11 and 12 via a connector 13 and a hot plate temperature detector 14. In response to the input of a humidity or temperature value established by the user via the dial and the other inputs, the command determines whether (or at what level) it is necessary to turn on the heating plate 7 to heat the water 6 located in the humidification chamber 5. When the volume of water 6 located in the humidification chamber 5

  is heated, steam begins to fill the volume of the chamber located

  above the surface of the water and is sent to the outside of the outlet 4 of the humidification chamber 5 with the flow of gases (for example air) supplied by

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  gas supply or blower means 15, which enter the chamber through the inlet 16. It should be noted that it is possible to obtain the relationship between the humidity of the gases

  located in the humidification chamber 5 and the temperature of the heating plate 7.

  As a result, it is possible to use the temperature of the heating plate in an algorithm or a look-up table to determine the humidity of the gases (correspondingly, the temperature of the heating plate acts as an indication of the humidity of the gases. gas and the two terms are used interchangeably in the present application). The gases exhaled through the patient's mouth are sent directly to the ambient environment in Figure 1. It should also be noted that in the preferred form of the present invention, the temperature of the hot plate is used to represent humidity, however, any suitable humidity detector can be used as an alternative. The blower 15 is provided with variable pressure regulation means or with a variable speed fan 21 which displaces air or other gases through the inlet 17 of the blower, producing a resulting gas flow. The speed of the variable speed fan 21 is controlled by other control means or an electronic control 18 (or alternatively the function of the control 18 can be executed by the control 9) in response to inputs from the control 9 and at a predetermined required value established via a dial 19 by the user (preset value) of the flow rate or of the pressure or of the fan speed (as mentioned above in relation to the temperature of the heating plate and humidity, it is also possible to determine a relationship between fan speed, gas flow and gas pressure and the three terms are therefore used

  interchangeable in this application).

  A preferred alternative embodiment of a humidified continuous positive pressurization system of the respiratory tract is shown in Figure 2 where the humidifier has been incorporated into the blower 15 so that the system has only one main component connected to the patient via the same conduit 3 and the same nasal mask 2. A single command 9 is necessary in this embodiment. This humidified continuous positive pressure system of the respiratory tract can be installed in any one of the two modes of implementation of a mode of

  "preheating" included in the above description. All digital references

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  common with Figure I represent the same features of the present invention. It is possible to control the way in which the heating plate and / or the blower fan are energized during "preheating" (any period during which the heating plate has not reached its established or required temperature). In the following we will describe two preferred examples of control methodology,

used in this period.

  In the use of a first preferred "preheat" mode, a user of the humidified continuous positive airway pressurization system 10 determines an "established" (or required) value for the gas pressure (Peta) to be sent by the blower 15 to the patient 1. This established value is sent to the control 18 by the dial 19. The user also determines an "established" (or required) value for the temperature (Teta) of the hot plate 7 which is entry into control 9 via dial 10. The user input dial for the set temperature can be marked with the word "Humidity" to assist the user. The control 9 then determines the current temperature of the hot plate 7 (Tactu) via the detector 14 and the current gas pressure (Pactu), for example, via the speed detector 20. It should be noted gases can take up to 30 minutes to reach their established humidity level, depending on the ambient conditions, flow rates and any obstructions in the patient's airways (e.g. inflammation). The current pressure value can be determined by a pressure or flow detector located in the blower 15, the humidification chamber 5 or the conduits connecting the system or, alternatively, as already mentioned, the speed of the fan 21 (detected by the speed sensor 20 or, alternatively, the speed instruction issued to the fan by control 18 can be used as the current fan speed) can be used to represent the

gas pressure.

  Control 9 then uses the established and current values of temperature (representing humidity) and pressure (or fan speed) to control humidification and pressure of the gas flow to patient 1. The pressure and temperature (humidity) of the gases sent to the patient will eventually be able to reach their value set by the user, however, to ensure that the patient is always supplied with humidified gases which have been saturated with the

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  maximum possible quantity of water vapor (within the currently existing limits of the humidifier), control 9 controls the speed of fan 21, in stages, using the humidity of the gases (or in stages using the hot plate temperature 7). As an example (with reference to Figures 3 and 4), the following table establishes the detected (initial) and established (or required) temperature and pressure values

  (relative) (equivalent to fan speed) when the system starts.

  Temperature Initial Pressure 20 C 0 Established 50 C 980 Pa (10 cm H20) Command 9 then determines the required pressure change (AP) and the required temperature change (AT) to obtain the required established pressure and temperature, respectively, of the system. In this case: AP = 980 Pa (10 cm H2O) AT = 30 C Command 9 then determines the average speed required for the pressure increase relative to the temperature by dividing AP by AT. In this case, this

  calculation results in 980 Pa (10 cm H2O) / 30 C or 32.66 Pa per C (1/3 cm H2O by C).

  Consequently, for each increase in IC of the temperature of the hot plate 7, the control 9 will send an instruction to the control 18 to increase the speed of the fan 21 to obtain an increase of 32.66 Pa (1/3 cm H20) pressure in this example. In this way, the temperature and pressure of the gases sent to the patient will reach their value established at the same time (that is to say, a time ts in FIGS. 3 and 4). Preferably, the hot plate will be energized when the humidified continuous positive pressurization system of the respiratory tract is triggered and will gradually increase in temperature to its established temperature (as shown in FIG. 4) at which time the control 9 will continuously and appropriately remove the voltage sent to the heating plate and then switch the heating plate back on to maintain the established temperature. It will be noted that the control 9 can continuously monitor the temperature of the plate until the established temperature

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  is reached and continuously determine the required average speed update of the increase values, or the required average increase speed determined initially will be able to be used over the entire preheating period. In this way, the patient will always receive only humidified gases because at startup a small amount of water vapor which is present in the humidification chamber 5 will be transported by a slight flow of gas while when the hotplate reaches its required set value (and therefore more water vapor is created in the humidification chamber) the blower will be controlled to

  produce a higher gas flow rate.

  We will now describe a second preferred embodiment of "preheating". It should be noted that all the references indicated and described with reference to

  Figures I and 2 are involved in this second embodiment.

  As in the previous preferred embodiment, the humidified continuous positive airway pressurization system according to this preferred embodiment has a "preheat" function which determines how the engine speed (and therefore the flow rate) supplied or the supplied pressure) of the fan 21 increases over time after the device has been triggered. Therefore, it is desirable to increase the pressure and therefore the resulting flow when humidity increases and therefore to achieve the desired set pressure when the

  humidity output of the device reaches its required equilibrium or level.

  The control 9 uses a closed loop control of the temperature of the heating plate 7 to reach the desired humidity level as soon as possible. Tests have indicated that the temperature of the hot plate alone (as used in the previous embodiment) is not necessarily a very good indicator of the humidity sent to the patient and that a significantly better indicator of the humidity is the temperature of the water in the humidification chamber 5. It should also be noted that the increase in the temperature of the water is much slower than that of the heating plate 7 because the water is extremely low when it comes to energy transfer. Controlling the fan speed only on the basis of the temperature of the heating plate can lead too quickly to excessive flow rates in the preheating cycle. Although the water temperature is not directly

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  measured (it would be impractical if not impossible to include a temperature detector inside the humidification chamber 5), it is possible to estimate in a reasonably precise manner how the temperature of the water in the

  humidification chamber 5 as will be described below.

  The mass heat of water describes the amount of heat (or energy) that is required to increase a unit of water mass by one degree. When the humidified continuous positive pressurization machine of the respiratory tracts is triggered according to this preferred embodiment of the present invention, the control 9 measures the current temperature of the heating plate 7 (assumed to be equal to the temperature of the water at stable state) and also receives an input consisting of the established temperature of the hot plate (or required) from a user (via a user interface comprising buttons, switches or dials for example). Command 9 then determines the required change in temperature to reach the established (or required) humidity value. Preferably, the control 9 uses 90% of the required temperature change since the temperature of the water in the humidification chamber 5 always reaches only 90% of the value of the established temperature of the hot plate 7 for conditions stable state. Using the value of the required temperature change (or a percentage thereof), and knowing the mass of water located in the chamber (assuming that the humidification chamber 5 is filled with 400 ml of equivalent water at a mass of 400 g), the amount of energy

  required to increase the water to the set temperature, can be calculated.

  As the command 9 also controls the energization of the heating plate 7, for example by controlling the useful cycle (timeactive / l (timeactive + cutting time) of the element, the amount of energy transferred to water by the plate Heating element 7 is known, for example, for an 85 watt heating element with an efficiency of 60%, an energy of 51 Joules is transferred to the water every second. The energy is taken from the water by two means

  dominants which are conduction and convection.

  Conduction losses are transferred through the walls of the chamber and the conduit. During preheating and in a stable state, the amount of energy lost through conduction losses is directly proportional to the temperature gradient between water and ambient temperature (air temperature). By knowing the temperature of the water and the temperature of the ambient air (via for example there 2779965 an ambient temperature sensor 22 or more preferably by estimating a fixed temperature say 20 C), the losses d Conduction energy (Econd) can be estimated during preheating. In this embodiment, the water temperature is not directly measured, however, tests have indicated during preheating, that the difference between the average water temperature and the ambient temperature is about 68% of the difference between the temperature of the hot plate and the ambient temperature, i.e. (Teau - Tambiante) = 0.68 x (Tplaque - Tambiantc). This approximation of the water temperature was obtained by sampling the hot plate and the water temperature over the preheating period, dividing the water temperature by the temperature of the hot plate and then establishing the average of the resulting values during the preheating period (from start up until gases are supplied to their

humidity level required).

  Convection losses are due to a flow of air through the water located in the humidification chamber 5. For the average flow of a user of a continuous positive pressure system of the respiratory tract, the flow ( Q) in liters per minute is directly proportional to the speed (v) of the fan motor 21 in revolutions per minute, for a given restriction (assuming for example a standard duct having a length of 2 m (6 feet)) and the Convection losses are approximately directly proportional to the flow. From the experiments, the appropriate proportionality constants have been determined and are incorporated into the equations below. Therefore, energy loss by convection (Eoov) can be estimated. Consequently, at any time in time the net amount of energy transferred (Etran) to the water located in the humidification chamber 5 can be

2 5 calculated.

  In use (and with reference to FIG. 5) the preheating algorithm according to the second preferred embodiment of the present invention acts as follows: A Ignoring the Losses 1. When the pressurizing device is put into service humidified continuous positive airway, control 9 reads the required or established ventilator speed and temperature (representing gas pressure and humidity) from user inputs 19 and 10 respectively and also the present temperature

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  (Tdcm) of the hot plate 7, remembering that the water temperature is approximately 90% of that of the hot plate 7. The fan 21 is energized at a low initial speed, for example 3000 revolutions per minute , to create an initial pressure and a resulting flow rate for example of 16 liters per minute (it is assumed that the flow rate (Q) in liters per minute is directly proportional to the speed of the fan motor (v) in revolutions per minute in a system continuous positive airway pressure, so that Q = v / 186.2). The amount of energy required (Erequise) to increase the temperature of the mass (m) of water located in the humidification chamber 5 by an amount (AT = (Trequise - Tdem) x 0.9) up to its established temperature is then calculated as follows (where k5 is the thermal mass capacity of the water): Required total = ks xmx AT = 4.19 x 103 x 0.4 x (Trequise - Tdem.) x 0.9 La control 9 then energizes the heating plate 7 in such a way (for example a closed loop control system adjusting the efficiency of the voltage applied to the heating element) that a predetermined required heating plate temperature (for example of approximately 60 C) is obtained as soon as

  possible with minimal overshoot, if not none.

  2. At predetermined time intervals (Tf), for example every 30 seconds, the amount of net energy (Etransfc, ee) which has been transferred to water in this interval from the heating plate 7 (having a nominal power of Pr watts and an efficiency of D (%)) is calculated Etransfcrce = Pr x tf x D Etransf &, có = 85 x 30 x D = 2550 x D [for a period of 30 seconds] This value is then subtracted of the total energy required to heat the water to the set temperature, which gives the energy required (for this point in time) to reach the set temperature. Thus initially: Encccssaire (dcm.) = Etotalc required - EtansfCrcc, = 4,19x 103x0,4 x (Trequise - Tdem.) X 0,9 - (2550 x D) and more generally for each iteration (i) which follows: Enecessaire (i) = Enecessaire (il) - 2550 x D)

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  3. Using the net energy transferred to water during the last 30 seconds or rather the average speed of net energy transfer (Ptransfert), and the newly calculated value of the energy required to reach the established temperature, a estimated time (ts) to reach the established temperature can be established as follows: Ptransfer = Etransferee / 30 [in Watts] and ts = Enéccssairc / Ptransfert therefore initially ts = (30 x Necessary (total / Etransfcré [in seconds] and for the iterations that follow an estimated update time (ts (i)) can be calculated as follows: ts (i) = (30 x (Necessary (i-1) - Etransférée (i))) / Eltransfree (i) [in seconds] B Including Losses But, as indicated above, the amount of energy loss from the water located in the humidification chamber via conduction and convection losses can also be taken into account The losses by conduction and convection can can be calculated as follows: Econv = kconv x Q AND Q = kQ xv therefore Econv = onv x kQ xv = (1 / 186.2) x 5.79 xv [for a period of 30 seconds] also Econd = kcond x (Teau - Tambiantc) = 10.83 x 0.68 x (Tpla.chauf - 20) = 7.4 x Tplachauf - 148 [in Joules for a period of 30 seconds during preheating] the losses are added to Necessary and subtracted of Etransferred, so that Enecessairc (reclle) = Encccssaire (il) Etransféree (i) + Econv (i) + Econd (i) Etransferée (reelle) = Etransferec (i) - Econv (i) - Econd (i) and therefore

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  (30 X (Necessary (il) - Etransférée (i) + Econv (i) + Econd (zl,)) ts (i) = (Etransférée (il) - Econv (i) - Econd (i) or alternatively: (30 (I_ (2560x X + (1 / "Meâ 9 X + (7.4 XTiaa -140) ts (ó) = ((250 X - ((-1 / 1 x 5.79 x - (7.4 x T , - 1i) 4. Using this calculated time and the difference between the established speed and the actual speed an average speed increase speed (y) can be calculated: Y = (Vrequise Vréelle (i)) / ts (i ) [in number of revolutions per second] The actual speed of the motor will then be adjusted accordingly to produce

the calculated acceleration.

  z 0 5. Steps 2 to 4 are repeated every 30 seconds (the required value of Etotale being reduced by the net amount of energy transferred Etransferce, for water in the previous seconds) so that the time to reach the set temperature and the required average increase in engine speed are calculated continuously

  when the rate of net energy transfer to the humidification chamber changes.

  This step is repeated until the time to reach the set temperature (t) is zero and the set speed is reached, at which time the water temperature in

  the humidification chamber 5 has also reached its required or established temperature.

  It should be noted that the algorithm described above assumes that the humidification chamber contains 400 ml of water. If the chamber has less than 400 ml, then the preheating time will be longer than the time that the smaller quantity of water will take to reach the established temperature, causing the working cycle of the element to stabilize more quickly at a lower level, the result being a lower net energy transfer speed (F = -F: -E) to water. Under experimental conditions, the warm-up times for a humidified continuous positive pressure machine of the respiratory tract varied between about 15 and 25 minutes depending on the operating conditions.

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  It will also be noted that in the preferred embodiment above, the speed of the fan is essentially controlled as a function of a water temperature determined indirectly. However, as explained above, it is desirable to control the pressure of the gases sent to the patient as a function of the humidity of these gases. The pressure (P) and the flow (Q) in the system described above (having a length of approximately 2 m (6 feet) etc.) can be approximated by the following equation: P = 8.836 x 10-3Q2

  As a result, the pressure increases with the square of the fan speed.

  However, with the above equation, it is possible to use the fan speed as a pressure indication and calculate the gas pressure from it. Similarly, it is possible to produce an equation relating temperature to humidity, for example by determining the mass of water evaporating per second and dividing this value by the existing flow. Therefore, although this preferred embodiment of the present invention has been described with reference to fan speed and temperature, the system still ensures that the gas pressure is

  controlled to the patient with adequately humidified gases only.

  The known relationships between fan speed and pressure and temperature and humidity can also be used in step 1 described above so that the user can enter required pressure and humidity values directly in the device. Control 9 can then calculate the required fan speed and temperature values and execute the remaining steps accordingly. The graphs shown in Figure 5 show that the temperature of the hot plate reaches its established temperature relatively quickly and that, due to the control system described above with reference to the second preferred embodiment, the fan speed ( in revolutions per minute in Figure 5)

  increases more gradually, in line with the increase in water temperature.

  We will now make other considerations.

  In cases where the temperature of the hot plate is close to the temperature established at system start-up (for example when the patient has used the device but has been called temporarily elsewhere and has switched off the device or placed the

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  device in a standby mode), the controller can avoid maintaining the temperature and pressure when they increase. In this case, the control can first of all determine whether the actual temperature of the heating plate is approximately 75% of its required set value above or above or, alternatively, say at 5 C of its established value. If this is the case, then the speed of the fan 21 is controlled to increase linearly from a certain low initial value to the established value required over a predetermined period of time (for example 15 minutes). Alternatively, the controller can determine if the actual temperature of the hot plate is within a range, for example, of about 10 C, of the required set temperature value, and then control the speed of the fan 21 to reach the set value of the

  fan speed in a predetermined period of time.

  The above mentioned steps are required due to the fact that when the hot plate is already hot it quickly reaches its set temperature (before the patient has fallen asleep) and therefore the full speed of the ventilator must be delayed by an established period to allow gases to be humidified in the humidifier's ability to humidify gases and / or to allow the user to fall asleep before maximum flow occurs. The predetermined period of time can be established by the manufacturer before selling the device or alternatively this value can be controlled by the user for example by adding a

  another dial and another input to the control 9.

  The control also preferably monitors the calculated net energy transfer value (Enett) and if it is found to be zero or negative (for example a second 30 second period), then it is decided that preheating should be stopped (because there is less energy required since start-up than what has been calculated because there is less water than expected in the room). In this situation, the fan speed is automatically increased to the set fan speed. Another feature can be the management of the preheating period so that if the preheating still exists after 25 minutes, then the fan speed can be increased automatically up to the speed of

  fan established when the warm-up period should be completed.

  An additional possibility may be the provision of a button having an input to control 9. The button can be pressed by the user to start the period of linear increase in the fixed fan speed

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  above. When preheating is finished (temperature and pressure have reached their required values), the user may find that he has been unable to bring him to sleep and therefore it is necessary that the fan speed be temporarily reduced. In this case, the user can simply press the button mentioned above and another linear increase in fan speed will occur (even if the water temperature is already at its required set temperature) by starting at a speed predetermined low and increasing linearly to the

established speed required.

  Accordingly, the present invention provides a humidified breathing aid system in which the patient is supplied with beneficially humidified gases during the period when the humidifier is warming up and also when the humidifier is in operation (and at its temperature established). In addition, the humidity of the gases sent to the patient is maintained over all of these two periods within the limits of the humidifier's ability to humidify these gases until they are beneficial to the patient. This is extremely beneficial to the patient since even a flow of unhumidified or inadequately humidified gases to the patient for a short period of time (e.g. 10 minutes) can cause destructive swelling of the nasal passages and even more discomfort. great if

food is oral.

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Claims (20)

  1. Breathing aid device suitable for supplying gases to a patient (1) to aid in the patient's breathing, comprising: - gas supply means (15), comprising pressure regulation means ( 21) adapted to supply gases at a pressure required with a resulting gas flow, - gas pressure detection means for determining the pressure of the gases supplied and therefore the resulting gas flow, - humidification means (8 ) which receive and humidify the gases supplied before sending them to the patient (1), the humidification means (8) being able to humidify the gases in a controlled manner to a required level of humidity, - means (3) forming a transport path which channels the humidified gases towards the patient (1), - means for detecting the humidity of the gases to determine the humidity of the gases supplied to the patient (1), and characterized in that - means command (9, 18) comm andent the gas supply means (15) in response to information regarding gas humidity and gas pressure and resulting gas flow, provided by the gas humidity detecting means and the detecting means gas pressure, so that the gas pressure and the resulting flow reach the required pressure and the resulting flow practically the same   time the required humidity level is reached.   2. Breathing aid device according to claim 1, characterized in that the humidification means (8) comprise means (5) forming a humidification chamber adapted to receive a volume of water (6) and heating means which can be switched on (7) to heat the volume of water (6) to produce water vapor in the means (5) forming a humidification chamber, the gases passing through the steam water located in the means (5) forming a humidification chamber thus being moistened.   3. Breathing aid device according to claim I or 2, characterized in that the pressure regulation means (21) comprise a speed ventilator 19 2779965   variable and the pressure detection means comprise a speed detector which detects the fan speed to indicate to the control means (9, 18) the flow gases.   4. Breathing aid device according to claim 2 or 3, characterized in that the means for detecting the humidity of the gases are a part of the control means (9, 18) and comprise means for detecting the temperature. heating means which can be energized (7), the humidity of the gases being estimated on the basis of the detected temperature of the heating means which can be energized (7). 5. Breathing aid device according to claim 2 or 3, characterized in that the means for detecting the humidity of the gases are a part of the control means (9, 18) and comprise means for detecting the temperature. heating means which can be energized (7). the humidity of the gases being estimated on the basis of a calculated value of the temperature of the volume of water (6) located in the humidification means (8), the calculated temperature value being determined by adding a quantity depending on the amount of energy that has been added to the volume of water (6) at the   detected temperature of the heating means which can be switched on (7).   6. Breathing aid device according to any one of claims 1 to   , characterized in that the control means (9, 18) consist of a programmable processor having in memory a program which, when executed in the processor, performs the steps consisting in: i) determining the total quantity d energy required to be transferred to the humidification means (8) to reach the required humidity level, ii) determine the current rate of energy transfer to the humidification means (8), iii) calculate the time for reach the required humidity level by dividing the total amount of required energy determined in step (i) by the energy transfer rate determined in step (ii), and iv) controlling the regulation means of pressure (21) to give the gases coming from the gas supply means (15) a pressure which is substantially similar in proportion to the pressure required when the humidity of the gases is at the required humidity level, 2779965   steps (i) to (iv) being repeated until the gases supplied are substantially humidified to the required humidity level and are substantially at pressure   required and at the resulting debit required.   7. Breathing aid device according to claim 6, characterized in that the energy transfer rate of step (ii) is estimated by determining the amount of energy transferred to the humidification means (8 ) for a predetermined period of time and dividing the amount of energy determined by the predetermined period of time. 8. Breathing aid device according to claim 7, characterized in that a first quantity equal to the estimated losses of energy by convection in the respiration aid device and a second quantity equal to the estimated losses of energy by conduction in the breathing aid device, are added to said determined quantity to calculate the time to reach the required humidity level of step (iii).   1 5 9. Breathing aid device according to claim 6 or 8, characterized in that a first quantity equal to the estimated losses of energy by convection in the respiration aid device and a second quantity equal to estimated losses of energy by conduction in the breathing aid device, are subtracted from the total amount of energy transferred to the humidification means (8) to calculate the   time to reach the required humidity level of step (iii).   10. Breathing aid device according to any one of claims 7   to 9, characterized in that the predetermined period of time is approximately 30 seconds.   He. Breathing aid device according to any one of claims 6   to 10, characterized in that step (i) involves the calculation of an initial quantity of energy required and the subtraction of the quantity of energy subsequently transferred to the means   humidification (8) in the previous predetermined periods of time accumulated.   12. Breathing aid device according to any one of claims 1   1, characterized in that the transport path means (3) comprises path heating means which are adapted to be energized in a controlled manner by the control means (9, 18) to reduce condensation along   the length of the means (3) forming the transport path. 21 2779965   13. Breathing aid device according to any one of claims 1   to 12, characterized in that it further comprises variable input means by the user who in response to an input by an operator causes the control means (9, 18) to control the means (15) d gas supply to achieve a predetermined pressure profile of the gases supplied regardless of the humidity of the   gas, over a period of time determined by the input made by the operator.   14. Breathing aid device according to claim 13, characterized in that the predetermined pressure profile of the gases supplied is a rising linear ramp starting from a lower initial pressure towards a final pressure equal to the pressure required.   15. Method for actuating a breathing aid device, the breathing aid device comprising means (15) for supplying gas, means (12) for regulating the pressure of suitable gases for supplying gases at a required pressure with a resulting gas flow, gas humidification means (8) capable of controlled humidification of the gases to a required humidity level, transport means (3 ) which channel the humidified gases towards the patient (1) and control means (9, 18) memorizing predetermined required pressure and humidity values, the method comprising the steps consisting in: a) triggering the humidification means gases (8) for humidifying the gases coming from the gas supply means (15), b) detecting the pressure of the gases, c) detecting the humidity of the gases, and characterized in that d) the pressure at which the gases are supplied to the patient (1) is ordered from the te that the gas pressure and the resulting flow reach the required pressure and the resulting flow required at approximately the same time that the required humidity level is reached. 16. Method according to claim 15, characterized in that the humidification means (8) comprise means (5) forming a humidification chamber adapted to receive a volume of water (6) and heating means that can be put energized (7) to heat the volume of water (6) to produce water vapor in 22 2779965   the means (5) forming a humidification chamber, the gases passing through the water vapor situated in the means (5) forming a humidification chamber being thus humidified. 17. Method according to claim 15 or 16, characterized in that the pressure regulation means (21) comprise a variable speed fan and the step of detecting the pressure and the flow rate resulting from the gases comprises the step consisting in: detecting the fan speed to provide the control means (9. 18) with a   indication of the pressure and flow resulting from the gases.   18. The method of claim 16 or 17, characterized in that the step of detecting the humidity of the gases consists in estimating the humidity on the basis of the   temperature of the heating means which can be energized (7).   19. The method of claim 16 or 17, characterized in that the step of detecting the humidity of the gases consists in estimating the humidity on the basis of a calculated value of the temperature of the volume of water (6) located in the humidification means (8), the calculated temperature value being determined by detecting the temperature of the heating means which can be energized (7) and by adding to it a quantity which is a function of the quantity of energy that has been added in the volume water (6).   20. Method according to any one of claims 15 to 19, characterized in that   o that step (d) further comprises the steps of: 1) determining the total amount of energy that it is necessary to transfer to the humidification means (8) so that the humidity of the gases reaches the humidity level required,   2) determine the rate of energy transferred to the humidification means (8).   3) calculate the time to reach the required humidity level by dividing the total amount of required energy determined in step (1) by the energy transfer rate determined in step (2), 4) order the pressure regulating means (21) so that they deliver the gases coming from the gas supply means (15) at a pressure which is substantially similar in proportion to the pressure required when the humidity of the gases is at the level d humidity required, 23 2779965   and in that steps (1) to (4) are repeated until the gases supplied are substantially humidified to the level of humidity required practically at the level of   required pressure and resulting gas flow.   21. The method of claim 20, characterized in that step (2) involves determining the amount of energy transferred to the humidification means (8) in a predetermined period of time and dividing the amount of 'energy   determined by the predetermined period of time.   22. Method according to claim 21, characterized in that a first quantity equal to the estimated losses of energy by convection in the breathing aid device and a second quantity equal to the estimated losses of energy by conduction in the device of breathing aid, are added to said quantity determined for   calculate the time to reach the required humidity level from step (iii).   23. Method according to any one of claims 20 to 22, characterized in that   that a first quantity equal to the estimated losses of energy by convection in the breathing aid device and a second quantity equal to the estimated losses of energy by conduction in the breathing aid device, are subtracted from the total amount of energy transferred to the humidification means (8) to calculate the   time to reach the required humidity level of step (iii).   24. Method according to any one of claims 21 to 23, characterized in that   That the predetermined period of time is about 30 seconds.   25. Method according to any one of claims 20 to 24. characterized in that   that step (1) involves the calculation of an initial quantity of energy required and the subtraction of the quantity of energy added thereafter to the humidification means   in the previous predetermined time periods accumulated.   2 5 26. Method according to any one of claims 15 to 25, characterized in that   that path heating means contained in the means (3) forming the transport path are energized in a controlled manner by the control means (9, 18) to reduce condensation along the length of the means (3) forming path transport.   27. Method according to any one of claims 15 to 26, characterized in that   that the breathing aid device further comprises variable input means by the user, and the control means (9, 18) control the means (15) 2 4 2779965   supply of gas to achieve a predetermined pressure profile of the gases supplied independently of the humidity of the gases over a period of time, in response to input by an operator, the predetermined time being determined by the input of the operator. 28. The method of claim 27, characterized in that the predetermined pressure profile of the gases supplied is a linear rising ramp starting from a pressure   lower initial towards a final pressure equal to the required pressure.