JP6793351B2 - Nasal CPAP element - Google Patents

Description

The present invention relates to a nasal CPAP element.

Nasal Continuous Positive Airway Pressure (CPAP) therapy, which pumps pressurized air through the nose to remove airway obstruction, ensures positive airway pressure in the lungs, such as in patients with neonatal respiratory distress syndrome. It is widely practiced to do.
Patent Document 1 includes an air supply pipe connection port to which an air supply tube is connected, a nasal prong port to which a nasal prong is connected, an exhaust pipe connection port to which an exhaust tube is connected, and a cavity communicating with the nasal prong port. In the Nasal CPAP element, the opening direction of the exhaust pipe connection port is opposite to the opening direction of the nasal prong port, and the opening direction of the air supply pipe connection port is the same as the opening direction of the exhaust pipe connection port or the nasal prong port. One flow path of the air, which is the direction, the nozzle that ejects the air flowing in from the air supply pipe connection port in a direction substantially perpendicular to the inflow direction, the splitter that divides the air ejected from the nozzle into two, and the air that is divided into two by the splitter. The first branch path forming the above, the second branch path that guides the other of the divided air to the exhaust pipe connection port, the first branch path and the discharge path that guides the air flowing out of the cavity to the exhaust pipe connection port, and the first A nasal CPAP is disclosed that comprises a guide vane between the two branch paths and blocking the inflow of air flowing out of the discharge path into the second branch path.

Japanese Unexamined Patent Publication No. 2014-18575

In the Nasal CPAP described in Patent Document 1, the expiratory pressure fluctuates greatly.

The nasal CPAP element according to the first aspect of the present invention includes an air supply tube connection port to which an air supply tube is connected, a nasal prong port to which a nasal prong is connected, an exhaust pipe connection port to which an exhaust tube is connected, and the nasal prong. A nasal CPAP element having a cavity communicating with a port, a nozzle for ejecting air flowing in from the air supply pipe connection port, a splitter for dividing the air ejected from the nozzle, and air divided by the splitter. The first branch path forming one flow path, the second branch path that guides the other of the divided air to the exhaust pipe connection port, and the exhaust of the air flowing out from the first branch path and the cavity. The discharge passage leading to the pipe connection port and a guide vane between the second branch passage and the discharge passage to prevent the inflow of air flowing out from the discharge passage into the second branch passage are provided. The width of the exhaust passage is narrower on the exhaust pipe connection port side than the width on the first branch road side, and the side surface of the discharge passage on the first branch road side and far from the nozzle is ejected from the nozzle. It is located downstream of the end of the potential core of the air.

According to the Nasal CPAP according to the present invention, fluctuations in expiratory pressure can be reduced.

The figure which shows the use state of a nasal CPAP element The figure which shows the outline structure of the Nasal CPAP element in embodiment The figure which shows the dimensional shape of each part in a nasal CPAP element Comparative Example A diagram showing the configuration of an element Figure showing time series change of CPAP pressure Figure showing CPAP fluctuation pressure Diagram showing the relationship between the width of the narrowest part of the discharge channel and pressure fluctuation Diagram showing measurement points on the splitter The figure which shows the pressure change near the stagnation point when the width of the narrowest part of a discharge path is 1.6 mm and 2.8 mm. FIG. 10A is a vector diagram showing the flow state of the Nasal CPAP element, and FIG. 10B is a vector diagram showing the flow state of the comparative example element. Diagram showing the effect of the width of the narrowest part of the discharge channel on the flow velocity The figure which shows the flow rate characteristic when the width of the narrowest part of a discharge path is 1.6 mm. The figure which shows the flow rate characteristic when the width of the narrowest part of a discharge path is 2.8 mm. The figure which shows the MAP-supply flow rate characteristic of the creation element obtained in the state which did not operate a newborn spontaneous breathing simulator. The figure which shows the time-series change of CPAP pressure obtained by operating the neonatal spontaneous-respiration simulator The figure which shows the CPAP waveform when the MAP pressure is changed in a plurality of ways The figure which shows the CPAP pressure fluctuation component which subtracted the MAP of each series in FIG. Diagram showing the effect of ventilation volume on CPAP pressure The figure which shows the outline structure of the Nasal CPAP element in the modification

(Embodiment)
An embodiment of the nasal CPAP device according to the present invention will be described with reference to FIGS. 1 to 19.
FIG. 1 is a diagram showing a usage state of the Nasal CPAP element 30. The nasal CPAP element 30 is used by being inserted into the newborn's nasal cavity to assist the newborn's breathing. Air is supplied to the nasal CPAP element 30 from an air pressure source at a constant pressure. Hereinafter, the pressure of air supplied from the Nasal CPAP element to the nasal cavity is referred to as "CPAP pressure". Since CPAP pressure is effective as a treatment for respiratory disorders and apnea treatment, it is desirable that the CPAP pressure is approximately constant throughout the newborn's respiratory cycle, that is, inspiration and expiration.
Although the nasal CPAP element 30 described in the present embodiment is for newborn babies, it can be applied to other than newborn babies by changing the air pressure supplied from the air pressure source and the shape of the nasal CPAP element 30.

(Constitution)
FIG. 2 is a diagram showing the configuration of the Nasal CPAP element 30. The nasal CPAP element 30 is composed of an air flow path formed in a space sandwiched between two flat plates and a plurality of connection ports. The nasal CPAP element 30 includes an air supply tube connection port 31 to which an air supply tube is connected, a nasal prong ports 32 and 33 to which a nasal prong is connected, a cavity 35 communicating with the nasal prong ports 32 and 33, and an exhaust tube. One of the exhaust pipe connection port 34 to be coupled, the nozzle 36 that ejects the air flowing in from the air supply pipe connection port 31, the splitter 37 that divides the ejected air of the nozzle 36 into two, and the air divided by the splitter 37 (hereinafter, A first branch path 38 forming a flow path of (referred to as "first jet") and a second branch path leading the other of the bisected air (hereinafter referred to as "second jet") to the exhaust pipe connection port 34. 39, a discharge path 40 that guides the air flowing out from the first branch path 38 and the cavity 35 to the exhaust pipe connection port 34, and a guide 42 that guides the air flow at the branch positions of the first branch path 38 and the discharge path 40. A guide vane 41 that prevents the air flowing out from the discharge path 40 and the air flowing out from the second branch path 39 from interfering with each other and preventing the backflow of air from the discharge path 40 to the second branch path 39, and a blunt head 44. , HFO flow path 43. The four points of Vin, Vd, Vent, and Vup in the figure indicate the points where the flow velocity was calculated in the explanation described later.

The nasal prongs coupled to the nasal prong ports 32, 33 are inserted into the nose of the newborn. The nasal prong ports 32 and 33 open downward in FIG. 2, and the exhaust pipe connecting port 34 opens upward in the opposite direction. Here, the air supply pipe connection port 31 is opened upward like the exhaust pipe connection port 34, but may be configured to open downward like the nasal prong ports 32 and 33. The air supply pipe connection port 31 has an opening on the upper side in the drawing, but has an opening on the left side in the drawing so that the direction of the air flowing in from the air supply pipe connection port 31 and the direction of the air ejected from the nozzle 36 are substantially the same. It may be configured in.
The nozzle 36 ejects the constant pressure air flowing in from the air supply pipe connecting port 31 in a direction substantially perpendicular to the inflow direction (to the right in FIG. 2).

The tip of the splitter 37 is located at substantially the same height as the upper side of the opening of the nozzle 36 on FIG. 2, and divides the air ejected from the nozzle 36 into two. The tip of the nozzle 36 is rounded.
The first branch path 38 has parallel inner walls and forms a linear flow path downward by about 15 °. The end of the first branch path 38 opens above the cavity 35. The first branch path 38 acts as a diffuser that reduces the flow velocity of the air ejected from the nozzle 36 and restores the CPAP pressure. The opening of the first branch passage 38, which is the outlet of the diffuser, is adjacent to the opening of the discharge passage 40, and the guide has rounded corners at the boundary position between the opening of the first branch passage 38 and the opening of the discharge passage 40. There are 42.

The inner wall 392 inside the element and the inner wall 393 outside the element forming the second branch path 39 are curved respectively, and the concave curved surface of the inner wall 392 has a radius of curvature shorter than the concave curved surface of the inner wall 393. Hereinafter, the cavity formed by the curved inner walls 392 and 393 will be referred to as a "sub-cavity" 390.
The discharge passage 40 has a vertically long shape in the drawing, and the width of the discharge passage 40 is narrower on the side of the exhaust pipe connection port 34 on the upper side of the drawing than on the side of the first branch passage 38 on the lower side of the drawing. The region on the exhaust pipe connection port 34 side of the discharge passage 40 and having the narrowest width in the discharge passage 40 is referred to as a “drainage narrowest portion” 401. Further, the wall surface forming the narrowest part 401 of the discharge path, that is, the wall surface on the right side of the drawing, that is, the side far from the nozzle 36, is referred to as the "narrowest part far wall" 401R. Further, a region on the downstream side of the second branch road 39 and adjacent to the narrowest portion 401 of the discharge path via the guide vane 41 is referred to as an "adjacent portion" 391.

A blunt head 44 is provided below the narrowest far wall 401R. The obtuse head 44 is an obtuse-angled protrusion having a predetermined radius of curvature, and is provided at a position where the air ejected from the nozzle 36 and passing through the first branch path 38, that is, the jet flow collides. The jet flow that has passed through the first branch path 38 is affected in the vertical direction shown by the inflow and outflow of air from the nasal prong ports 32 and 33 that change according to the respiratory cycle. Since the blunt head 44 has a rounded shape, the tip of this jet smoothly changes in the vertical direction shown in the figure according to the breathing cycle. Further, the upper portion of the blunt head 44 has a concave shape, and a jet stream bent upward in the drawing at the time of exhalation tends to flow out from the exhaust passage 40 to the exhaust pipe connection port 34 due to the entrainment effect.

The second jet, which flows out of the nozzle 36 and is split by the splitter 37, flows along the wall of the subcavity 391 of the second branch path 39 and forms a vortex. Further, the inner wall 401 on the outer side of the element constituting the discharge path 40 is slightly bulged outward. Therefore, the air separated from the guide 42 and flowing into the discharge path 40 flows along the inflated inner wall 401 to form a vortex immediately after the guide 42. The vortices generated in the subcavity 390 and the discharge path 40 are accompanied by negative pressure. Therefore, the second jet is easily drawn in from the inflow port of the second branch path 39, and the outflow air from the first branch path 38 and the cavity 35 is easily drawn in from the inflow port of the discharge path 40.
The HFO flow path 43 is a flow path for carrying out a high frequency vibration ventilation method (High Frequency Oscillation Ventilation). In the present embodiment, no air flow is generated in the HFO flow path 43.

FIG. 3 is a diagram showing the dimensions of the Nasal CPAP element 30. The Nasal CPAP element 30 is an air flow path formed in a space having a predetermined width, for example, a width of 2 mm, which is mainly formed by two flat plates. The width of the nozzle 36, that is, the height in the vertical direction in FIG. 3 is, for example, 1.1 mm. In the present embodiment, the width of the nozzle 36 is set as the reference dimension d, and the other dimensions and the radius of curvature are shown below using the reference dimension d.

The width of the first branch path 38 is preferably 1.3d to 1.7d. The angle formed by the first branch path 38 in the horizontal direction shown in the drawing is, for example, 15 degrees, but may be another angle. The entrance dimension of the subcavity 390, that is, the opening from the downstream end of the nozzle 36 to the splitter 37 is preferably 1.2d to 1.4d. Further, the exit dimension of the second branch path 39, that is, the width of the adjacent portion 391 is preferably 1.3d to 1.6d. The width of the narrowest portion 401 of the discharge path adjacent to the adjacent portion 391 and the guide vane 41 is preferably 2.6d to 3.2d. Further, as will be described in detail later, the ratio of the width of the adjacent portion 391 to the width of the narrowest discharge path 401 is most preferably 1: 2, and preferably in the range of 1: 1.7 to 1: 2.05.

The distance from the outlet of the nozzle 36 to the narrowest far wall 401R in the direction in which the nozzle 36 ejects air is preferably 5d to 7d. This distance is the length of the potential core, which is the region where the velocity does not decrease. The dimension from the end of the nozzle 36 to the wall surface of the cavity 35, which is farther from the nozzle 36, is preferably 9.0d to 10d.
The obtuse head 44 preferably has a radius of curvature of 0.5d to 0.7d, and is preferably an obtuse angle, that is, larger than 90 degrees as shown in FIG. The vertical position of the blunt head 44 is determined based on the angle formed by the first branch path 38 in the horizontal direction and the flow velocity of the air ejected from the nozzle 36.

(Numerical calculation)
The result of numerical calculation will be described. The result of the numerical calculation when the width of the narrowest part 401 of the discharge path is changed will be described together with a comparative example not provided with the splitter 37 or the second branch path 39.

<Comparative example element configuration>
FIG. 4 is a diagram showing a configuration of a comparative example element 90 not provided with a splitter 37 or a second branch path 39. Comparative Example When the element 90 and the nasal CPAP element 30 are compared, the splitter 37 and the second branch path 39 are excluded from the configuration of the nasal CPAP element 30, and the total amount of air ejected from the nozzle 36 becomes the first branch path 98. Inflow. The width of the outlet of the discharge path 99 in the comparative example element 90, that is, the width corresponding to the narrowest discharge path 401 in the Nasal CPAP element 30 is 2.8 mm.

<CPAP pressure>
The width of the adjacent portion 391 of the nasal CPAP element 30 is fixed to 1.4 mm, and the width of the narrowest discharge path 401 is 1.6 mm, 2.0 mm, 2.4 mm, 2.8 mm, 3.0 mm, 3.2 mm. The calculation result of the CPAP pressure when changed to is shown in FIG. In this calculation, the supply flow rate to the air supply pipe connection port 31 is 7 L / min, the simulated breathing through the nasal prong ports 32 and 33 is 50 times per minute, the ventilation volume at one time is 20 ml, and it is sinusoidal. I set it.

5 and 8 are diagrams showing numerical calculation results, FIG. 5 is a diagram showing a time-series change in CPAP pressure, FIG. 6 is a diagram showing CPAP fluctuation pressure, and FIG. 7 is a discharge path ratio described later and a diagram described later. It is a figure which shows the relationship of the pressure fluctuation width. In FIG. 5, only a part of the widths of the plurality of discharge path narrowest portions 401 described above is shown, and the calculation result using the comparative example element 90 is also shown.

In FIG. 5, 0 seconds to 0.6 seconds are times corresponding to the exhalation of simulated respiration, and 0.6 seconds to 1.2 seconds are times corresponding to inspiration. When the width of the narrowest discharge path 401 is 1.6 mm, the CPAP pressure fluctuation range (hereinafter referred to as "pressure fluctuation range") is 60 Pa or more, but when the width is 2.0 mm, the pressure fluctuation range sharply decreases. However, when the width is 2.8 mm, the pressure fluctuation width is further reduced. In the comparative example element 90, the width of the outlet of the discharge path 99 is 2.8 mm, but the pressure fluctuation width is 100 Pa or more, and the width of the narrowest discharge path 401 of the nasal CPAP element 30 is 1.6 mm. Also has a large pressure fluctuation range.

In FIG. 6, the widths of the narrowest portion 401 of the discharge path are 2.8 mm and 1.6 mm, and the CPAP fluctuating pressure obtained by subtracting the respective MAP pressures, that is, the expiratory pressure immediately before entering the inspiration, from the three types of CPAP pressures of the comparative example element 90 It is a figure which shows. Since the jet flow from the nozzle reaches the blunt head 44, the intake characteristic of the comparative example element 90 starts to decrease at the start of intake and decreases to about −90 Pa in 0.9 seconds.

FIG. 7 is a diagram showing the relationship between the value obtained by dividing the width of the narrowest portion 401 of the discharge path by the width of the second branch path 39 (hereinafter, referred to as “discharge path ratio”) and the pressure fluctuation width. That is, the plot at the left end in FIG. 7 corresponds to the case where the width of the narrowest portion 401 of the discharge path is 1.6 mm, and the plot at the right end corresponds to the case where the width is 3.2 mm. From FIG. 7, it can be seen that the pressure fluctuation range decreases as the discharge path ratio increases, but the pressure fluctuation range starts to increase when the discharge path ratio exceeds 2. For example, it can be seen that the pressure fluctuation width is suppressed to less than 15 Pa when the discharge path ratio is 1.7 to 2.05, as shown by the broken line in FIG.

<Pressure change near the stagnation point>
Next, the pressure change near the stagnation pressure at the same measurement point on the splitter 37 when the width of the narrowest discharge path 401 of the Nasal CPAP element 30 is 1.6 mm and 2.8 mm will be described. Before explaining the calculation result of the pressure change, the measurement points will be described.
FIG. 8 is a diagram showing measurement points on the splitter 37. FIG. 8 (b) is an enlarged view of the tip of the splitter 37 shown in FIG. 8 (a). As shown in FIG. 8B, measurement points L1, L2, ... L10 are defined at the tip of the splitter 37. That is, the measurement point L5 is the surface of the splitter 37 and is a point 38 degrees from the illustrated horizontal plane. The adjacent measurement points L4 and L6 are separated from each other by 2 degrees, and the other measurement points are also separated from each other by 2 degrees.

FIG. 9 is a diagram showing a pressure change near the stagnation point when the width of the discharge path narrowest portion 401 of the Nasal CPAP element 30 is 1.6 mm and 28 mm. When the width of the narrowest discharge path 401 is 1.6 mm, the magnitude relationship between the pressures at the measurement points L3 and L7 is switched between the time of expiration and the time of inspiration, indicating that the stagnation point is moving. The fluctuation range of the pressure over one cycle of the simulated respiration is about 400 Pa. On the other hand, when the width of the narrowest portion 401 of the discharge path is 2.8 mm, the calculation results of the adjacent measurement points L7 and L8 are almost the same and are displayed overlapping in FIG. 9. More specifically, the measurement points are displayed. The calculation results of L7 and L8 change over the entire cycle of simulated respiration while maintaining a predetermined difference. This calculation result indicates that the stagnation point does not move when the width of the narrowest portion 401 of the discharge path is 2.8 mm. The fluctuation range of the pressure over one cycle of the simulated respiration at this time is about 100 Pa.

<Vector diagram>
FIG. 10 is a vector diagram showing the flow states of (a) Nasal CPAP element 30 and (b) Comparative example element 90, respectively. The time is 0.3 seconds from the start of exhalation, that is, 0.3 seconds in FIG. In the Nasal CPAP element 30, the jet jet flowing out of the nozzle is split at the tip of the splitter 37 immediately after the nozzle, and is divided into a second jet from the second branch path 39 to the outside and a first jet from the splitter flow path to the cavity. Divided into. The first jet is along the upper part of the splitter 37, and its width narrows toward the rear end of the splitter 37. The first jet after passing through the rear end of the splitter does not reach the wall of the discharge path 40, but bends upward like the tip of a whip on the way, and flows toward the upper outlet together with the expiratory flow.
As described above, at the time of exhalation, the first jet flow is separated from the wall of the discharge path 40, and a smooth outflow state in which the exhalation flow flows from the inside of the element to the outside of the element is observed.

On the other hand, in the flow of the comparative example element 90, the entire jet jet is bent downward due to the shape of the flow path immediately after the nozzle outlet, and flows in the vicinity of the first branch path 98. It can be seen that the width of this mainstream is thicker than that of the Nasal CPAP element 30 and is maintained up to the vicinity of the exit. After passing through the splitter flow path, the mainstream is bent upward and along the wall, but a part of it collides with the wall of the discharge path 40 and heads downward.
As described above, in the comparative example element 90, since the exhaled air flows out while colliding with the wall of the discharge path 40, it is considered that the exhaled air flow is hard to flow out to the outside and circulates. From the above, it is considered that the behavior of the mainstream after passing through the splitter flow path in the device is the same as that of the air curtain jet. That is, since the mainstream of the Nasal CPAP element 30 is narrow and the jet pressure is weak, it is bent by the expiratory pressure, and the mainstream is separated from the wall of the discharge path 40. Comparative Example The mainstream of the element 90 has a wide width and the jet pressure is stronger than the expiratory pressure, so that the jet reaches the wall of the discharge path 40. As a result, it is considered that most of the expiratory flow does not flow out and forms a circulating flow in the cavity.

FIG. 11 is a diagram showing the effect of the width of the narrowest portion 401 of the discharge path on the flow velocity. In FIG. 11, the velocities at the three points shown in FIG. 2 are shown for each of the case where the width of the narrowest portion 401 of the discharge path is 1.6 mm and the case where the width is 2.8 mm. Vup is the velocity that is branched by the splitter 37 and flows into the subcavity 390, Vcent is the velocity at the center of the first branch path 36 in the length direction, and Vd is the velocity near the exit of the first branch path 36. .. Further, in FIG. 11, the outlet speed of the nozzle 36 is shown as Vin for comparison.
When the width of the narrowest part 401 of the discharge path is 2.8 mm, the velocities of Vup, Vcent, and Vd at each measurement point have little fluctuation and are substantially constant throughout one cycle of simulated respiration. Since there is little fluctuation in this way, it can be seen that when the width is 2.8 mm, the influence of respiration on the flow velocity is small. On the other hand, when the width of the narrowest portion 401 of the discharge path is 1.6 mm, the Vcent does not fluctuate, but the Vd at the outlet of the splitter 37 flow path greatly fluctuates. This Vd has a higher speed than Vin, and it is considered that this is because the circulation flow in the cavity is added as the third flow because the speed fluctuation due to Vent and respiration is less than that speed. Be done.

12 and 13 are diagrams showing the flow rate characteristics. FIG. 12 shows a case where the width of the narrowest part 401 of the discharge path is 1.6 mm, and FIG. 13 shows a case where the width of the narrowest part 401 of the discharge path is 2.8 mm. In each of the figures, D1 is the flow rate passing through the lower surface of the splitter 37, D2 is the flow rate flowing out from the discharge path 40, and D3 is the flow rate flowing out from the second branch path 39. In the case of the outlet flow path of 1.6 mm shown in FIG. 12, D1 and D2 have substantially the same amplitude and have an opposite phase relationship, and D3 also fluctuates greatly. On the other hand, when the width of the narrowest portion 401 of the discharge path shown in FIG. 13 is 2.8 mm, the fluctuations of D1 and D3 are small and almost constant, and D2 has the breathing amount indicated by N in FIG. 12 in the flow rate of D1. It has been added.
The above results indicate that the movement of the mainstream after passing through the splitter flow path has a dominant effect on the fluctuation of CPAP pressure. Further, it is also shown that the narrowest discharge path 401 of the Nasal CPAP element 30 needs to have a sufficient width, and that the splitter 37 needs to divide the jet jet from the nozzle at a constant ratio in order to further narrow the mainstream width. There is.

(Experimental result)
A Nasal CPAP element (hereinafter referred to as "creating element 30A") in which the width of the adjacent portion 391 is 1.4 mm and the width of the narrowest discharge path 401 is 2.8 mm is manufactured, and the experimental results using this are explained. To do. However, in some experimental results, only the width of the narrowest discharge path 401 is different from that of the created element 30A, and the width of the narrowest discharge path 401 is 1.6 mm (hereinafter referred to as "1.6 mm element"). ) Is also shown.
FIG. 14 shows the MAP-supply flow rate characteristics obtained by attaching the manufactured element 30A to the newborn spontaneous-respiration simulator and not operating the newborn spontaneous-respiration simulator. MAP is the mean average pressure of CPAP pressure, that is, the average pressure. In FIG. 14, the experimental results of the created element 30A are shown in a circle plot, and the experimental results using a 1.6 mm element are shown in a square plot for comparison. Comparing the two, the MAP-supply flow rate characteristics are almost the same. That is, since the supply flow rate is about 5.1 L / min to obtain a MAP of 500 Pa, which is almost the same flow rate as that of the 1.6 mm element, it is considered that the steady flow in this element is close to that of the 1.6 mm element.

FIG. 15 is a diagram showing time-series changes in CPAP pressure obtained by operating a newborn spontaneous-respiration simulator using the created elements 30A and 1.6 mm elements. The settings of the newborn spontaneous breathing simulator are MAP of 500 PaP, exponential waveform during respiration, and ventilation volume of 7 ml. As shown in FIG. 15, the pressure waveform when the creating element 30A is used has an amplitude of half or less as compared with the case where the 1.6 mm element is used, and in particular, the pressure at the time of exhalation is significantly reduced. There is. The reason for this is that the outlet resistance is reduced due to the expansion of the outlet area, which is consistent with the result of the numerical calculation described above. However, the intake characteristic has dropped to about −90 Pa, and this negative pressure value is almost the same as the result of the negative pressure value at the time of intake of the comparative example element 90 in FIG. From the above, when a flow rate of about 5.1 L / min is supplied to the creating element 30A, the flow inside the element is a flow in which the main flow collides with the wall of the discharge path 40 as in the comparative example element 90, and is at the time of exhalation. In the above case, the mainstream is separated from the wall of the discharge path 40 after passing through the splitter, as in the case of the Nasal CPAP element 30 in which the width of the narrowest discharge path 401 shown in FIG. 10A is 2.8 mm. is expected.

FIG. 16 is a diagram showing a CPAP pressure waveform when the newborn spontaneous respiration simulator is set to have a ventilation volume of 7 ml and a respiration rate of 50 times / minute, and the air pressure supplied so as to reach a predetermined MAP pressure is changed in a plurality of ways. is there. However, the predetermined MAP pressure was set in 6 ways from 300 Pa to 800 Pa in 100 Pa increments. The CPAP pressure waveforms in FIG. 16 are similar to the waveform at the time of inspiration, indicating that the influence of the MAP pressure is small. Therefore, only the fluctuating pressure amplitude component is extracted and the effect of MAP is investigated.

FIG. 17 is a diagram showing pressure fluctuation components of each series in FIG. 16, that is, pressure obtained by subtracting the set MAP pressure from the pressure of each series. According to FIG. 17, when the MAP pressure increases during inspiration, the negative fluctuation amount slightly increases, but the amplitude is almost the same regardless of the MAP pressure. However, at the time of exhalation, the pressure decreases as the MAP pressure increases. For example, at a MAP pressure of 800 Pa, the pressure drops to about −40 Pa. It is considered that this is because the distance between the wall of the discharge passage 40 and the mainstream gradually increases as the MAP pressure increases, so that the expiratory flow increases and the pressure decreases.

FIG. 18 is a diagram showing the results of examining the effect of ventilation volume on CPAP pressure with the MAP pressure kept constant at 500 Pa. From FIG. 18, it can be seen that the CPAP pressure is less affected by the ventilation volume during exhalation, but the CPAP pressure decreases as the ventilation volume increases during inspiration. The rate of pressure drop was about -15 Pa / ml. This is because as the ventilation volume increases, the speed of the intake air flow increases and the pressure decreases. On the other hand, it can be seen that the waveform during exhalation has almost no effect on CPAP pressure even if the ventilation volume increases.

According to the above-described embodiment, the following effects are obtained.
(1) The nasal CPAP element 30 includes an air supply pipe connection port 31 to which an air supply tube is connected, a nasal prong ports 32 and 33 to which a nasal prong is connected, an exhaust pipe connection port 34 to which an exhaust tube is connected, and a nasal prong port. A cavity 35 that communicates with the cavity 35 is provided. The nasal CPAP element 30 forms one flow path of the nozzle 36 that ejects the air flowing in from the air supply pipe connection port 31, the splitter 37 that divides the air ejected from the nozzle 36 into two, and the air divided by the splitter 37. The first branch path 38, the second branch path 39 that guides the other of the divided air to the exhaust pipe connection port, and the discharge path 40 that guides the air flowing out from the first branch path 38 and the cavity 35 to the exhaust pipe connection port 34. A guide vane 41 located between the second branch path 39 and the discharge path 40 to prevent the air flowing out from the discharge path 40 from flowing into the second branch path 39 is provided. The width of the exhaust passage 40 on the exhaust pipe connection port 34 side is narrower than the width of the first branch road side 38. The side surface of the discharge path 40 on the side of the first branch path 38 and far from the nozzle 36 is located downstream of the end of the potential core of the air ejected from the nozzle 36.
Since the blunt head 44 is located downstream of the end of the potential core of the air ejected from the nozzle 36, the air flowing out from the cavity 35 easily passes near the blunt head 44 and the exhaust pipe connection port 34. Can be reached. Therefore, when the air flows into the cavity 35 from the nasal prong ports 32 and 33, the air flowing into the cavity 35 can smoothly reach the exhaust pipe connecting port 34, so that the fluctuation of the expiratory pressure can be reduced.

(2) From the outlet of the nozzle 36 in the direction in which the nozzle 36 ejects air, the narrowest discharge path 401 of the discharge path 40 and the side surface far from the nozzle 36, that is, the narrowest far wall. The distance to the 401R is 5 times or more and 7 times or less the width of the nozzle 36.
Since the distance from the outlet of the nozzle 36 to the narrowest far wall 401R is the outlet width, which is the general length of the potential core, that is, 5 to 7 times the width of the nozzle 36, the cavity 35 is passed through the discharge path 40. This causes resistance in the path leading to the exhaust pipe connection port 34. Therefore, the pressure of the cavity 35 can be kept higher than the atmospheric pressure.

(3) The second branch road 39 has an adjacent portion 391 adjacent to the discharge path narrowest portion 401 via the guide vane 41. The width of the narrowest discharge path 401 is 1.7 to 2.05 times the width of the adjacent portion 391.
As shown in FIG. 7, when the discharge path ratio is 1.7 to 2.05, the fluctuation range of the CPAP pressure is suppressed to less than 15 Pa, and the fluctuation of the pressure of the air supplied to the nose can be reduced.

(4) The width of the adjacent portion 391 is 1.4 mm, and the width of the narrowest discharge path 401 is 2.8 mm. Therefore, it is possible to provide a nasal CPAP element suitable for a newborn baby.
(5) A rounded obtuse-angled protrusion, that is, an obtuse head 44 is provided on the side surface of the discharge path 40 on the side far from the nozzle 36. The blunt head 44 is provided at a position where the air ejected from the nozzle 36 and passing through the first branch path 38 collides with the air. Therefore, the stagnation point can move smoothly on the blunt head 44 in the respiratory cycle, that is, the transition from inspiration to expiration.

(Modification example)
In the embodiment described above, the Nasal CPAP element 30 includes an HFO flow path 43. However, as shown in FIG. 19, the Nasal CPAP element does not have to include the HFO flow path 43. FIG. 19 is a diagram showing the configuration of the Nasal CPAP element 30A in the modified example. The nasal CPAP element 30A is the same as the nasal CPAP element 30 shown in FIG. 2, except that it does not include the HFO flow path 43 shown by the broken line, including the dimensions of each part.

30 ... Nasal CPAP element, 36 ... Nozzle, 37 ... Splitter, 38 ... First branch path, 39 ... Second branch path, 391 ... Adjacent part, 40 ... Discharge path, 41 ... Guide vane, 401 ... Narrowest part of discharge path , 401R ... Narrowest far wall, 44 ... Dull head

Claims (4)

A nasal CPAP element including an air supply tube connection port to which an air supply tube is connected, a nasal prong port to which a nasal prong is connected, an exhaust pipe connection port to which an exhaust tube is connected, and a cavity communicating with the nasal prong port. hand,
A nozzle that ejects air flowing in from the air supply pipe connection port and
A splitter that divides the air ejected from the nozzle into two,
A first branch path forming one flow path of air divided by the splitter, and
A second branch path that leads the other of the bisected air to the exhaust pipe connection port,
An exhaust path that guides the air flowing out of the first branch path and the cavity to the exhaust pipe connection port, and
It is provided with a guide vane between the second branch passage and the discharge passage to prevent the air flowing out from the discharge passage from flowing into the second branch passage.
The discharge path includes the narrowest part of the discharge path, which is the narrowest.
The width of the exhaust pipe connection port side is narrower than the width of the first branch road side.
The side surface of the discharge path on the side of the first branch path far from the nozzle is located downstream of the end of the potential core of the air ejected from the nozzle .
The second branch road has an adjacent portion adjacent to the narrowest portion of the discharge passage via the guide vane, and the width of the narrowest portion of the discharge passage is relative to the width of the adjacent portion. A nasal CPAP element that is 1.7 to 2.05 times . In the Nasal CPAP element according to claim 1,
In a direction in which the nozzles for ejecting air from the outlet of the nozzle, the distance to the side remote from the nozzle a said discharge path narrowest part is the following seven times more than five times the width of the nozzle Nasal CPAP element. In the Nasal CPAP element according to claim 1 or 2 .
A nasal CPAP element having a width of the adjacent portion of 1.4 mm and a width of the narrowest portion of the discharge path of 2.8 mm. In the Nasal CPAP element according to any one of claims 1 to 3 .
The side surface of the discharge path on the side far from the nozzle is provided with a rounded obtuse angle protrusion.
The protrusion is a nasal CPAP element provided at a position where air ejected from the nozzle and passing through the first branch path collides with the protrusion.

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