JP2017038813A - Blood pump - Google Patents
Blood pump Download PDFInfo
- Publication number
- JP2017038813A JP2017038813A JP2015163030A JP2015163030A JP2017038813A JP 2017038813 A JP2017038813 A JP 2017038813A JP 2015163030 A JP2015163030 A JP 2015163030A JP 2015163030 A JP2015163030 A JP 2015163030A JP 2017038813 A JP2017038813 A JP 2017038813A
- Authority
- JP
- Japan
- Prior art keywords
- impeller
- bearing
- casing
- dynamic pressure
- blood pump
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 210000004369 blood Anatomy 0.000 title claims abstract description 46
- 239000008280 blood Substances 0.000 title claims abstract description 46
- 210000003743 erythrocyte Anatomy 0.000 claims abstract description 40
- 206010018910 Haemolysis Diseases 0.000 claims abstract description 18
- 230000008588 hemolysis Effects 0.000 claims abstract description 18
- 230000008878 coupling Effects 0.000 claims abstract description 4
- 238000010168 coupling process Methods 0.000 claims abstract description 4
- 238000005859 coupling reaction Methods 0.000 claims abstract description 4
- 239000007788 liquid Substances 0.000 claims abstract description 3
- 239000011347 resin Substances 0.000 claims description 15
- 229920005989 resin Polymers 0.000 claims description 15
- 230000002093 peripheral effect Effects 0.000 claims description 6
- 238000001727 in vivo Methods 0.000 claims description 2
- 238000005192 partition Methods 0.000 claims description 2
- 230000005389 magnetism Effects 0.000 abstract description 3
- 210000002381 plasma Anatomy 0.000 description 24
- 238000005534 hematocrit Methods 0.000 description 13
- 238000012360 testing method Methods 0.000 description 12
- 238000005339 levitation Methods 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 241000283690 Bos taurus Species 0.000 description 2
- 210000004204 blood vessel Anatomy 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000011859 microparticle Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 206010019280 Heart failures Diseases 0.000 description 1
- 210000000601 blood cell Anatomy 0.000 description 1
- 238000007675 cardiac surgery Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001356 surgical procedure Methods 0.000 description 1
Images
Abstract
Description
本発明は、人工心臓用、補助循環用および心臓手術用の血液ポンプに関するものであって、特に、スラスト軸受として、動圧溝であるスパイラル溝を用いたものに関する。また、血液ポンプ以外にも、微小粒子を流す産業用ポンプとして使用することもでき、あるいは、培養や薬液の微小粒子を輸送する生物分野の輸送用ポンプとしても使用できるものである。 The present invention relates to blood pumps for artificial heart, auxiliary circulation, and cardiac surgery, and more particularly, to a pump using a spiral groove as a dynamic pressure groove as a thrust bearing. In addition to the blood pump, it can also be used as an industrial pump for flowing microparticles, or it can be used as a transport pump in the biological field for transporting microparticles of culture or chemicals.
近年、医療技術等の進歩に伴い、人工心臓用、補助循環用及び心臓手術用のポンプとし
て遠心血液ポンプが用いられるようになってきた。
例えば、特許文献１では、流体力学的スラスト軸受を用いて、羽根車の非接触駆動を実現しているが、流体力学的スラスト軸受としての動圧溝は、いわゆるスパイラル溝を用いたものではない。
特許文献２〜４では、流体力学的スラスト軸受と吸引力を有する複数の永久磁石を用いて、羽根車の非接触駆動を実現しており、流体力学的スラスト軸受としての動圧溝にスパイラル溝を用いているが、溝深さに関する記載はあるものの、軸受隙間について記載されていない。
また、本出願人による特許文献５、６においても、スラスト動圧軸受としてスパイラル溝を用いたものを出願しているが、溝深さに関する記載は無く、特許文献５の羽根車下面の動圧溝はスパイラル溝ではない。
In recent years, with the advancement of medical technology and the like, centrifugal blood pumps have been used as pumps for artificial heart, auxiliary circulation, and heart surgery.
For example, in Patent Document 1, non-contact driving of an impeller is realized using a hydrodynamic thrust bearing, but a dynamic pressure groove as a hydrodynamic thrust bearing does not use a so-called spiral groove. .
In Patent Documents 2 to 4, non-contact driving of an impeller is realized by using a hydrodynamic thrust bearing and a plurality of permanent magnets having attraction force, and a spiral groove is formed in a dynamic pressure groove as a hydrodynamic thrust bearing. Although there is a description about the groove depth, the bearing clearance is not described.
Also, in Patent Documents 5 and 6 by the present applicant, there is a patent application using a spiral groove as a thrust dynamic pressure bearing, but there is no description regarding the groove depth, and the dynamic pressure on the lower surface of the impeller of Patent Document 5 The groove is not a spiral groove.
補助人工心臓に代表される補助循環用血液ポンプが重症心不全患者に適用されており、近年、血液ポンプには長期耐久性と高い血液適合性が求められるため、非接触軸受のひとつである動圧軸受が血液ポンプに応用されている（特許文献１〜５参照）。動圧軸受を有する血液ポンプの軸受隙間は、動圧軸受の原理上数十μｍと狭くなるため、狭い隙間に起因した赤血球破壊(溶血)が懸念される。一方、軸受隙間を溶血が改善される数百μｍまで広げると、動圧軸受の軸受剛性が低下し、インペラ（羽根車）の浮上が心拍の影響により不安定となってしまう。
したがって、本発明が解決しようとする課題は、軸受剛性を維持しながら、溶血の問題を改善させた血液ポンプを提供することにある。
A blood pump for auxiliary circulation represented by an auxiliary artificial heart has been applied to patients with severe heart failure. In recent years, blood pumps are required to have long-term durability and high blood compatibility. A bearing is applied to a blood pump (see Patent Documents 1 to 5). The bearing gap of a blood pump having a dynamic pressure bearing becomes as narrow as several tens of μm due to the principle of the dynamic pressure bearing, so there is a concern about erythrocyte destruction (hemolysis) due to the narrow gap. On the other hand, when the bearing gap is expanded to several hundred μm where hemolysis is improved, the bearing rigidity of the hydrodynamic bearing is lowered, and the impeller (impeller) becomes unstable due to the influence of the heartbeat.
Therefore, the problem to be solved by the present invention is to provide a blood pump in which the problem of hemolysis is improved while maintaining bearing rigidity.
そこで、軸受剛性を維持しながら、溶血の問題を改善させるため、赤血球と血漿が分離するプラズマスキミング現象に着目した。プラズマスキミングとは、生体内の血管において分岐した側の毛細管内の赤血球濃度（ヘマトクリット）が分岐前の血管のヘマトクリットよりも減少する現象である。動圧軸受を有する血液ポンプにおいて、十分な軸受剛性が得られる狭い軸受隙間でプラズマスキミングを生じさせ、高せん断となる軸受隙間で赤血球濃度を減少させることで、溶血の問題を改善させる。
すなわち、本発明は、流入口と流出口が設けられたケーシングと、前記ケーシング内で回転することによって前記流入口から流出口へ液体を送る羽根車と、前記羽根車内に内蔵された永久磁石と、前記永久磁石と隔壁越しに磁気カップリングを形成して前記羽根車を回転駆動する磁気発生装置と、前記羽根車と羽根車に対向する前記ケーシングのいずれかにスラスト動圧軸受を構成するスパイラル形状の動圧溝を備えた血液ポンプにおいて、前記羽根車と前記ケーシング間の前記スラスト動圧軸受の平均軸受隙間を２０μｍ以下とし、かつ、前記スラスト動圧軸受のスパイラル形状の動圧溝深さを５０μｍ以上とすることによりプラズマスキミング現象によってスパイラルグルーブ軸受の山側の狭い軸受隙間には血漿が入り、溝側のせん断応力が低い部分には赤血球が入るようにして溶血を防止したことを特徴とする。
また、本発明は、上記血液ポンプにおいて、前記羽根車のラジアル軸受として、前記ケーシングに設けた内筒と、前記内筒によりラジアル方向に支持される前記羽根車内側面と、のいずれかにヘリンボーン溝を設けてラジアル動圧軸受を構成し、前記羽根車とケーシング間のラジアル動圧軸受の平均軸受隙間を２０μｍ以下とし、ラジアル軸受の溝深さを５０μｍ以上としたことを特徴とする。
また、本発明は、上記血液ポンプにおいて、前記羽根車は樹脂にて構成され、該樹脂中に前記永久磁石が埋め込まれ、該永久磁石の外周面が樹脂により被覆され、前記ケーシングは樹脂にて構成され、前記駆動用の磁気発生装置の前記羽根車に内蔵された永久磁石に対向する内周面が樹脂により被覆されていることを特徴とする。
また、本発明は、上記血液ポンプにおいて、体内埋め込みの形式で使用するためのものである。
また、本発明は、上記血液ポンプにおいて、体外設置型の形式で使用するためのものである。
Therefore, in order to improve the hemolysis problem while maintaining the bearing rigidity, we focused on the plasma skimming phenomenon in which red blood cells and plasma are separated. Plasma skimming is a phenomenon in which the red blood cell concentration (hematocrit) in the capillary on the side branched in the blood vessel in the living body is lower than the hematocrit of the blood vessel before branching. In a blood pump having a hydrodynamic bearing, plasma skimming is generated in a narrow bearing gap where sufficient bearing rigidity is obtained, and the red blood cell concentration is reduced in a bearing gap that becomes high shear, thereby improving the problem of hemolysis.
That is, the present invention includes a casing provided with an inflow port and an outflow port, an impeller for sending liquid from the inflow port to the outflow port by rotating in the casing, and a permanent magnet built in the impeller. A magnetic generator for rotating the impeller by forming a magnetic coupling over the permanent magnet and the partition, and a spiral constituting a thrust hydrodynamic bearing in any of the casing facing the impeller and the impeller In the blood pump having a dynamic pressure groove having a shape, an average bearing clearance of the thrust dynamic pressure bearing between the impeller and the casing is set to 20 μm or less, and a spiral dynamic pressure groove depth of the thrust dynamic pressure bearing is set. By setting the diameter to 50 μm or more, plasma enters the narrow bearing gap on the peak side of the spiral groove bearing due to the plasma skimming phenomenon, and shear stress on the groove side It is characterized in that hemolysis is prevented by allowing erythrocytes to enter in the portion with a low value.
Further, the present invention provides the blood pump according to any one of the inner cylinder provided in the casing and the inner surface of the impeller supported in the radial direction by the inner cylinder as a radial bearing of the impeller. To form a radial dynamic pressure bearing, wherein an average bearing clearance of the radial dynamic pressure bearing between the impeller and the casing is set to 20 μm or less, and a groove depth of the radial bearing is set to 50 μm or more.
In the blood pump, the impeller is made of resin, the permanent magnet is embedded in the resin, the outer peripheral surface of the permanent magnet is covered with resin, and the casing is made of resin. It is comprised, The inner peripheral surface facing the permanent magnet built in the said impeller of the said magnetic generator for a drive is coat | covered with resin, It is characterized by the above-mentioned.
The present invention is also for use in the above-described blood pump in the form of implantation in the body.
Further, the present invention is for use in the above-described blood pump in an externally installed type.
本発明では、インペラとケーシング間の平均軸受隙間を２０μｍ以下としつつ、スパイラル形状のスラスト軸受の動圧溝深さを５０μｍ以上としたことにより、スパイラルグルーブ軸受の山側と溝側とでプラズマスキミング現象を現出させて、スパイラルグルーブ軸受の山側から赤血球を排除し、溶血の原因となるせん断応力の高いスパイラルグルーブ軸受の山側の狭い軸受隙間には血漿が入り、溝側のせん断応力が低い部分には赤血球が入るため、軸受剛性を維持しながら、溶血を改善する血液ポンプが実現できるものである。
本発明の血液ポンプは、体内埋め込みの形式でも、体外設置型の形式でも使用することができる。
In the present invention, the average bearing gap between the impeller and the casing is set to 20 μm or less, and the dynamic pressure groove depth of the spiral thrust bearing is set to 50 μm or more. In order to eliminate red blood cells from the crest side of the spiral groove bearing, plasma enters the narrow bearing gap on the crest side of the spiral groove bearing which has high shear stress, which causes hemolysis. Since red blood cells enter, a blood pump that improves hemolysis while maintaining bearing rigidity can be realized.
The blood pump of the present invention can be used both in an in-vivo type and in an external type.
本発明の血液ポンプは、赤血球と血漿が分離するプラズマスキミング現象に着目し、動圧軸受を有する血液ポンプにおいて、十分な軸受剛性が得られる狭い軸受隙間でプラズマスキミングを生じさせ、高せん断となる軸受隙間で赤血球濃度を減少させることで、溶血の問題を改善させたものであり、インペラ（羽根車）とケーシング間の平均軸受隙間を２０μｍ以下としつつ、動圧溝であるスパイラル形状のスラスト軸受の溝深さを５０μｍ以上とすることによりプラズマスキミング現象を発現させたものである。 The blood pump of the present invention pays attention to the plasma skimming phenomenon in which red blood cells and plasma are separated, and in a blood pump having a hydrodynamic bearing, plasma skimming occurs in a narrow bearing gap that provides sufficient bearing rigidity, resulting in high shear. Reduced red blood cell concentration in the bearing gap has improved the problem of hemolysis, and a spiral thrust bearing that is a dynamic pressure groove while maintaining an average bearing gap of 20 μm or less between the impeller (impeller) and the casing This causes the plasma skimming phenomenon to occur by setting the groove depth to 50 μm or more.
図１に、本発明の血液ポンプの一実施例を示す。図１のごとく本発明の血液ポンプは、流入口（インレット）と流出口（アウトレット）が設けられたケーシングと、ケーシング内で回転することによって流入口から流出口へ血液を送る羽根車（インペラ）と、羽根車に内蔵された永久磁石と磁気カップリングを形成しケーシングに内蔵された羽根車駆動用の磁気発生装置（コイル）と、羽根車と対向するケーシングに設けられたスラスト動圧軸受を構成するスパイラル形状の動圧溝とを有し、羽根車とケーシング間のスラスト方向の平均軸受隙間を２０μｍ以下としつつ、スパイラル形状のスラスト軸受の溝深さを５０μｍ以上に構成したものである。本形状によりプラズマスキミング現象が発現し、溶血の原因となるせん断応力の高い動圧軸受の山側の狭い軸受隙間には血漿が入り、溝側のせん断応力が低い部分には赤血球が入るため、軸受剛性を維持しながら、溶血を改善する血液ポンプが実現できる。なお、図１ではスパイラル形状の動圧溝はケーシング側に設けてあるが、羽根車側に設けてもよい。
また、ケーシング内筒の固定軸と、羽根車内側面とでラジアル動圧軸受けを構成しており、図では、４円弧溝による動圧軸受（本出願人による、特開２０１３−２１２２１８号公報参照）を採用しているが、ケーシング内筒と、前記内筒によりラジアル方向に支持される前記羽根車内側面と、のいずれかにヘリンボーン溝を設けてラジアル動圧軸受を構成した場合には、前記羽根車とケーシング間のラジアル動圧軸受の平均軸受隙間を２０μｍ以下とし、ラジアル動圧軸受のヘリンボーン溝深さを５０μｍ以上とすれば前記スパイラル形状の動圧溝と同様にプラズマスキミング現象が発現し、溶血の原因となるせん断応力の高い動圧軸受の山側の狭い軸受隙間には血漿が入り、溝側のせん断応力が低い部分には赤血球が入るため、軸受剛性を維持しながら、溶血を改善することができる。
また、羽根車を樹脂で構成し、該樹脂中に前記永久磁石を埋め込み、該永久磁石の外周面が樹脂により被覆されるようにし、前記ケーシングを樹脂で構成し、前記駆動用の磁気発生装置の前記羽根車に内蔵された永久磁石に対向する内周面が樹脂により被覆されるように構成することが望ましい。
上記のごとく構成された血液ポンプにおいて、羽根車駆動用の磁気発生装置に通電すると磁気発生装置と永久磁石との相互作用により羽根車が回転し、流入口から入った血液は羽根車のベーン間流路に入り、回転する羽根車から遠心力を与えられた血液はベーン間流路を通って流出口から吐出される。羽根車が回転すると、スラスト動圧軸受により羽根車が浮上し非接触でスラスト方向に支持され、ラジアル動圧軸受によりラジアル方向にも非接触で軸支される。
FIG. 1 shows an embodiment of the blood pump of the present invention. As shown in FIG. 1, a blood pump of the present invention includes a casing provided with an inlet and an outlet, and an impeller that feeds blood from the inlet to the outlet by rotating in the casing. And a magnetic generator (coil) for driving the impeller that forms a magnetic coupling with the permanent magnet built in the impeller and is built in the casing, and a thrust dynamic pressure bearing provided in the casing facing the impeller. A spiral-shaped dynamic pressure groove is formed, and an average bearing gap in the thrust direction between the impeller and the casing is set to 20 μm or less, and a groove depth of the spiral-shaped thrust bearing is set to 50 μm or more. This shape causes a plasma skimming phenomenon, and plasma enters the narrow bearing gap on the peak side of the hydrodynamic bearing with high shear stress that causes hemolysis, and red blood cells enter the portion on the groove side where the shear stress is low. A blood pump that improves hemolysis while maintaining rigidity can be realized. In FIG. 1, the spiral dynamic pressure groove is provided on the casing side, but may be provided on the impeller side.
Further, a radial dynamic pressure bearing is constituted by the fixed shaft of the casing inner cylinder and the inner surface of the impeller. In the figure, a dynamic pressure bearing with four arc grooves (refer to Japanese Patent Application Laid-Open No. 2013-212218 by the present applicant). However, when a radial dynamic pressure bearing is formed by providing a herringbone groove on either the casing inner cylinder and the impeller inner side surface supported in the radial direction by the inner cylinder, the blade If the average bearing clearance of the radial dynamic pressure bearing between the vehicle and the casing is set to 20 μm or less and the herringbone groove depth of the radial dynamic pressure bearing is set to 50 μm or more, the plasma skimming phenomenon appears like the spiral dynamic pressure groove, Plasma is contained in the narrow bearing gap on the peak side of the hydrodynamic bearing that has high shear stress, which causes hemolysis, and red blood cells enter the portion on the groove side where the shear stress is low. Hemolysis can be improved while holding.
Further, the impeller is made of resin, the permanent magnet is embedded in the resin, the outer peripheral surface of the permanent magnet is covered with resin, the casing is made of resin, and the driving magnetic generator It is desirable that the inner peripheral surface facing the permanent magnet built in the impeller is covered with resin.
In the blood pump configured as described above, when the magnetism generating device for driving the impeller is energized, the impeller rotates due to the interaction between the magnetism generating device and the permanent magnet, and the blood entering from the inlet is between the vanes of the impeller. Blood that enters the flow path and is given centrifugal force from the rotating impeller is discharged from the outlet through the inter-vane flow path. When the impeller rotates, the impeller floats by the thrust dynamic pressure bearing and is supported in the thrust direction without contact, and is axially supported by the radial dynamic pressure bearing in the radial direction without contact.
（作製例）
本発明の血液ポンプの作製例を以下に説明する。作成した動圧浮上遠心血液ポンプは、上面ケーシング、インペラ、および下面ケーシングから構成される。ポンプケーシングの直径は７３ｍｍで高さは５６ｍｍである。インペラ直径は３７ｍｍ、高さが２６ｍｍであり、６本のベーンを有するクローズドタイプである。インペラは、ラジアルおよびスラスト方向の動圧軸受によって支持される。上面ケーシング内側の円筒側面に４円弧形状のラジアル軸受を有する。上面および下面ケーシング表面には、スパイラルグルーブ形状のスラスト軸受を有する。スパイラルグルーブ軸受の溝数は１２本で、溝深さは１００μｍである。スラスト方向の上面隙間と下面隙間の合計は３００μｍである。インペラは、上面ケーシング内のステータコイルとインペラ内の永久磁石間の磁気力によって回転する。
(Production example)
A production example of the blood pump of the present invention will be described below. The created dynamic pressure levitation centrifugal blood pump is composed of an upper casing, an impeller, and a lower casing. The pump casing has a diameter of 73 mm and a height of 56 mm. The impeller has a diameter of 37 mm, a height of 26 mm, and is a closed type having six vanes. The impeller is supported by radial and thrust hydrodynamic bearings. A four-arc-shaped radial bearing is provided on the cylindrical side surface inside the upper casing. The upper and lower casing surfaces have spiral groove-shaped thrust bearings. The spiral groove bearing has 12 grooves and a groove depth of 100 μm. The total of the upper surface clearance and the lower surface clearance in the thrust direction is 300 μm. The impeller rotates by a magnetic force between a stator coil in the upper casing and a permanent magnet in the impeller.
（作製例のインペラ浮上特性試験）
インペラ浮上位置を評価するため、体循環系を模擬した模擬循環回路を使用したインペラ浮上特性試験を行った。図２に示すように、模擬循環回路は、リザーバ、チューブ、流路抵抗、および試験ポンプから構成される。作動流体には、ウシ保存血を使用した。ウシ血のヘマトクリット値は、自己血漿希釈により１.０％に調整した。リザーバは、３７℃の恒温槽につけた。インペラの浮上位置を計測するために、レーザ焦点変位計をポンプ下面側に設置した。駆動条件は、流路抵抗を用いて回転数２,８００ｒｐｍ時に揚程１００ｍｍＨｇ、流量５.０Ｌ／ｍｉｎとなるよう一定に保った。計測データはノートパソコンを用いてサンプリングした。サンプリング周波数は１ｋＨｚ、サンプリング時間は１０秒とした。１万個のデータから計測値の平均値を求めた。
(Impeller levitation characteristics test of production example)
In order to evaluate the impeller levitation position, an impeller levitation characteristic test using a simulated circulation circuit simulating the body circulation system was conducted. As shown in FIG. 2, the simulated circulation circuit is composed of a reservoir, a tube, a flow path resistance, and a test pump. Bovine stored blood was used as the working fluid. The hematocrit value of bovine blood was adjusted to 1.0% by autologous plasma dilution. The reservoir was attached to a constant temperature bath at 37 ° C. In order to measure the flying position of the impeller, a laser focal displacement meter was installed on the lower surface side of the pump. The driving conditions were kept constant using a flow path resistance so that the head was 100 mmHg and the flow rate was 5.0 L / min at a rotation speed of 2,800 rpm. The measurement data was sampled using a laptop computer. The sampling frequency was 1 kHz and the sampling time was 10 seconds. The average value of measured values was obtained from 10,000 pieces of data.
（作製例のプラズマスキミング評価試験）
図３に示すように、血液ポンプのスパイラルグルーブ軸受内の赤血球流れを評価するため、微視的観察を行った。ズームレンズを接続したハイスピードマイクロスコープをポンプ下面側に設置し、赤血球の挙動を録画した。シャッタースピードとフレームレートは、それぞれ１／９０００００ｓと８０００ｆｐｓとした。撮影時間は、インペラ３周期分とした。
(Plasma skimming evaluation test of production example)
As shown in FIG. 3, microscopic observation was performed to evaluate the red blood cell flow in the spiral groove bearing of the blood pump. A high-speed microscope connected with a zoom lens was installed on the bottom side of the pump, and the behavior of red blood cells was recorded. The shutter speed and frame rate were 1 / 900,000 s and 8000 fps, respectively. The shooting time was 3 impeller cycles.
（プラズマスキミングの評価方法）
スパイラルグルーブ軸受の山側のヘマトクリットを評価するため、微視的観察結果から山側のヘマトクリットを推定した。撮影動画は連続静止画に変換し、画像処理を用いて解析した。これらの画像は二値化することで赤血球を黒で表現し、山側の黒のピクセル数の合計を求めた。画像上の赤血球占有率を下記の式（１）から求めた。
Ｑ＝ＡE／ＡRidgs （１）
ここで、Ｑは画像上の赤血球占有率、は山側の赤血球のピクセル数の合計、ＡRidgsは山側のピクセル数の合計である。画像上の赤血球占有率は、散乱係数の概念から次式（２）でも表すことができる。
Ｑ＝μS×ｄｘ （２）
ここで、μSは単位厚さ当たりの赤血球占有率、ｄｘは血液層の厚さである。単位厚さあたりの赤血球占有率は、生体光学における散乱係数として知られており、下記式（３）で表される。
ΜS＝（ＨＣＴ／ＭＣＶ）σS （３）
ここで、ＭＣＶは平均赤血球容積、σSは赤血球の幾何断面積である。式（３）より、スパイラル溝の山側の推定ヘマトクリットＨＣＴは次式（４）より求められる。
ＨＣＴ＝（１／σS）×（ＭＣＶ×（Ｑ／ｄｘ）） （４）
ここで、ＭＣＶには血球分析装置で計測した値を、Ｑには式（１）より求めた赤血球占有率を、ｄｘにはインペラ浮上特性試験において計測した軸受隙間をそれぞれ代入した。赤血球をバイコンケーブ形状（両面にくぼみを有する形状）と仮定すると、バイコンケーブ状の赤血球の方程式は、次式（５）で表される。
ｒ（θ）＝３ｓｉｎ4θ＋０.７５ （５）
ここで、ｒ（θ）は赤血球表面の関数であり、ｒは半径、θは長軸とＺ軸とのなす角である。赤血球の長軸が球の半径と等しいと仮定すると、赤血球と球の体積比は次式（６）で表される。
Ｃ＝ＭＣＶ／ＶS （６）
ここで、Ｃは赤血球と球の体積比、ＶSは赤血球の長軸半径が球の半径と等しい場合の球の体積である。式（６）より、赤血球のＭＣＶと長軸半径の関係は、次式（７）で表される。
ｒb＝（３ＭＣＶ／４πＣ）1/3 （７）
ここで、ｒbは赤血球の長軸半径である。赤血球の幾何断面積σSは赤血球の長軸半径を用いて、次式（８）から求めた。
ΣS＝πｒｂ 2 （８）
最終的に、式（４）を元に、スパイラルグルーブ軸受山側のプラズマスキミング効率は、次式（９）より求めた。
ＥS＝｛１−（ＨＣＴ／ＨＣＴW）｝×１００ （９）
ここで、ＥSはスパイラル溝の山側のプラズマスキミング効率であり、ＨＣＴWは作動流体のヘマトクリットである。
(Plasma skimming evaluation method)
In order to evaluate the hematocrit on the mountain side of the spiral groove bearing, the hematocrit on the mountain side was estimated from the microscopic observation results. The captured video was converted to a continuous still image and analyzed using image processing. These images were binarized to express red blood cells in black, and the total number of black pixels on the mountain side was obtained. The erythrocyte occupancy on the image was determined from the following equation (1).
Q = A E / A Ridgs (1)
Here, Q is the occupancy rate of red blood cells on the image, is the total number of pixels of red blood cells on the mountain side, and A Ridgs is the total number of pixels on the mountain side. The red blood cell occupation ratio on the image can also be expressed by the following equation (2) from the concept of the scattering coefficient.
Q = μ S × dx (2)
Here, μ S is the red blood cell occupancy per unit thickness, and dx is the thickness of the blood layer. The occupancy rate of red blood cells per unit thickness is known as a scattering coefficient in biological optics and is represented by the following formula (3).
Μ S = (HCT / MCV) σ S (3)
Here, MCV is the average red blood cell volume, and σ S is the geometric cross-sectional area of red blood cells. From the equation (3), the estimated hematocrit HCT on the peak side of the spiral groove is obtained from the following equation (4).
HCT = (1 / σ S ) × (MCV × (Q / dx)) (4)
Here, the value measured by the blood cell analyzer was substituted for MCV, the erythrocyte occupancy obtained from equation (1) was substituted for Q, and the bearing clearance measured in the impeller levitation characteristic test was substituted for dx. Assuming that the erythrocytes are in a bi-concave shape (a shape having indentations on both sides), the equation of the bi-concave erythrocytes is expressed by the following equation (5).
r (θ) = 3 sin 4 θ + 0.75 (5)
Here, r (θ) is a function of the erythrocyte surface, r is a radius, and θ is an angle formed by the major axis and the Z axis. Assuming that the major axis of the red blood cell is equal to the radius of the sphere, the volume ratio of the red blood cell to the sphere is expressed by the following equation (6).
C = MCV / V S (6)
Here, C is the volume ratio of red blood cells and spheres, and V S is the volume of the sphere when the major axis radius of the red blood cells is equal to the radius of the sphere. From the equation (6), the relationship between the MCV of the erythrocyte and the long axis radius is expressed by the following equation (7).
r b = (3MCV / 4πC) 1/3 (7)
Here, r b is the major axis radius of the red blood cells. The geometric cross-sectional area σ S of red blood cells was obtained from the following equation (8) using the major axis radius of red blood cells.
Σ S = πr b 2 (8)
Finally, based on the equation (4), the plasma skimming efficiency on the spiral groove bearing crest side was obtained from the following equation (9).
E S = {1− (HCT / HCT W )} × 100 (9)
Here, E S is the plasma skimming efficiency on the peak side of the spiral groove, and HCT W is the hematocrit of the working fluid.
（評価結果）
図４は、ポンプの回転数を２,５００ｒｐｍ、２,８００ｒｐｍ、および３,０００ｒｐｍに変えて試験を行ったときの、インペラ浮上特性試験とプラズマスキミング評価試験の結果を示した図であり、図４の左側がポンプの回転数２５００ｒｐｍ、中央が回転数２８００ｒｐｍ、右側が回転数３０００ｒｐｍにおける結果である。図４の上側のグラフの左縦軸はヘマトクリット率を示し、右縦軸は軸受隙間を示す。ヘマトクリット率は、初期のヘマトクリットを１００％としたときのヘマトクリットの変化を示す。横軸はインペラの回転角度を示す。図４の下側の写真は、各回転数におけるスパイラルグルーブ軸受の溝側の軸受隙間と山側の軸受隙間を高速度カメラで撮影した写真であり、黒丸状に写っているのが赤血球である。
ポンプの回転数を２,５００ｒｐｍ、２,８００ｒｐｍ、および３,０００ｒｐｍに変えたとき、インペラとスパイラルグルーブ軸受山側間の距離である下面隙間は、それぞれ３０μｍ、２４μｍ、２０μｍとなった。このとき、下面隙間３０μｍ、２４μｍ、２０μｍに対して、スパイラルグルーブ軸受山側の推定ヘマトクリット率は、それぞれ７２％、２２％、３％となった。つまり、隙間を２０μｍとすることで、山側の赤血球は９７％減少し、スパイラルグルーブ軸受の山側から赤血球を排除することが出来た。本形状により、隙間を２０μｍ以下とすれば、溶血の原因となるせん断応力の高い動圧軸受の山側の狭い軸受隙間には血漿が入り、溝側のせん断応力が低い部分には赤血球が入るため、軸受剛性を維持しながら、溶血を改善する血液ポンプが実現できることが確認された。
(Evaluation results)
FIG. 4 is a diagram showing the results of the impeller levitation characteristic test and the plasma skimming evaluation test when the test was performed while changing the rotation speed of the pump to 2500 rpm, 2,800 rpm, and 3000 rpm. The left side of FIG. 4 shows the results at a pump rotational speed of 2500 rpm, the center at a rotational speed of 2800 rpm, and the right side at a rotational speed of 3000 rpm. The left vertical axis of the upper graph in FIG. 4 indicates the hematocrit rate, and the right vertical axis indicates the bearing clearance. The hematocrit rate indicates the change in hematocrit when the initial hematocrit is 100%. The horizontal axis indicates the rotation angle of the impeller. The lower photograph in FIG. 4 is a photograph of a spiral groove bearing groove-side bearing gap and a crest-side bearing gap at each rotational speed taken with a high-speed camera, and black circles represent red blood cells.
When the number of rotations of the pump was changed to 2500 rpm, 2,800 rpm, and 3000 rpm, the lower surface gaps, which are distances between the impeller and the spiral groove bearing crest side, were 30 μm, 24 μm, and 20 μm, respectively. At this time, the estimated hematocrit ratios on the spiral groove bearing crest side were 72%, 22%, and 3%, respectively, with respect to the bottom gaps of 30 μm, 24 μm, and 20 μm. That is, by setting the gap to 20 μm, the erythrocytes on the crest side decreased by 97%, and the erythrocytes could be excluded from the crest side of the spiral groove bearing. With this shape, if the gap is 20 μm or less, plasma will enter the narrow bearing gap on the mountain side of the hydrodynamic bearing with high shear stress causing hemolysis, and red blood cells will enter the portion on the groove side where the shear stress is low. It was confirmed that a blood pump that improves hemolysis while maintaining bearing rigidity can be realized.
本発明の血液ポンプは、医療機器である左心補助ポンプや体外循環用ポンプとして利用される。また、生物分野や産業機器分野において、微小粒子の入った溶液を送るための培養や薬液の輸送用ポンプや産業用ポンプとしても利用される。 The blood pump of the present invention is used as a left heart assist pump or extracorporeal circulation pump which is a medical device. In the biological field and industrial equipment field, it is also used as a culture pump for sending a solution containing fine particles, a pump for transporting chemicals, and an industrial pump.
Claims (5)
前記羽根車と前記ケーシング間の前記スラスト動圧軸受の平均軸受隙間を２０μｍ以下とし、かつ、前記スラスト動圧軸受のスパイラル形状の動圧溝深さを５０μｍ以上とすることによりプラズマスキミング現象によってスパイラルグルーブ軸受の山側の狭い軸受隙間には血漿が入り、溝側のせん断応力が低い部分には赤血球が入るようにして溶血を防止したことを特徴とする血液ポンプ。 A casing provided with an inflow port and an outflow port, an impeller for sending liquid from the inflow port to the outflow port by rotating in the casing, a permanent magnet built in the impeller, the permanent magnet and the partition wall A magnetic generator for rotating the impeller by forming a magnetic coupling over the casing, and a spiral-shaped dynamic pressure groove that constitutes a thrust dynamic pressure bearing in either of the casing facing the impeller and the impeller In the blood pump provided,
Spiral due to the plasma skimming phenomenon by setting the average bearing clearance of the thrust dynamic pressure bearing between the impeller and the casing to 20 μm or less and the spiral dynamic pressure groove depth of the thrust dynamic pressure bearing to 50 μm or more. A blood pump characterized in that hemolysis is prevented by allowing plasma to enter a narrow bearing gap on the peak side of the groove bearing and red blood cells to enter a portion having a low shear stress on the groove side.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015163030A JP6646296B2 (en) | 2015-08-20 | 2015-08-20 | How the blood pump works |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015163030A JP6646296B2 (en) | 2015-08-20 | 2015-08-20 | How the blood pump works |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2017038813A true JP2017038813A (en) | 2017-02-23 |
| JP6646296B2 JP6646296B2 (en) | 2020-02-14 |
Family
ID=58205863
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2015163030A Active JP6646296B2 (en) | 2015-08-20 | 2015-08-20 | How the blood pump works |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6646296B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112253452A (en) * | 2020-10-16 | 2021-01-22 | 扬州大学 | Design method of miniature disc pump with spiral flow channel |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004245303A (en) * | 2003-02-13 | 2004-09-02 | Mitsubishi Heavy Ind Ltd | Artificial heart pump |
| JP2008104664A (en) * | 2006-10-26 | 2008-05-08 | National Institute Of Advanced Industrial & Technology | Artificial heart pump equipped with dynamic pressure bearing |
| US20120089225A1 (en) * | 2010-10-07 | 2012-04-12 | EverHeart Systems LLC | High efficiency blood pump |
-
2015
- 2015-08-20 JP JP2015163030A patent/JP6646296B2/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004245303A (en) * | 2003-02-13 | 2004-09-02 | Mitsubishi Heavy Ind Ltd | Artificial heart pump |
| JP2008104664A (en) * | 2006-10-26 | 2008-05-08 | National Institute Of Advanced Industrial & Technology | Artificial heart pump equipped with dynamic pressure bearing |
| US20120089225A1 (en) * | 2010-10-07 | 2012-04-12 | EverHeart Systems LLC | High efficiency blood pump |
Non-Patent Citations (1)
| Title |
|---|
| 村重 智崇: "血液適合性改善を目的とした動圧浮上遠心血液ポンプのスパイラルグループ形状の検討", 人工臓器, vol. 第44巻,第1号, JPN6019007636, 15 June 2015 (2015-06-15), JP, pages 28, ISSN: 0003992166 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112253452A (en) * | 2020-10-16 | 2021-01-22 | 扬州大学 | Design method of miniature disc pump with spiral flow channel |
| CN112253452B (en) * | 2020-10-16 | 2022-02-22 | 扬州大学 | Design method of miniature disc pump with spiral flow channel |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6646296B2 (en) | 2020-02-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8894387B2 (en) | Hydrodynamic chamfer thrust bearing | |
| US9717832B2 (en) | Axial flow rotor with downstream bearing wash flow | |
| EP1481699A1 (en) | Passive non-contacting smart bearing suspension for turbo blood-pumps | |
| US20080262289A1 (en) | Blood Pump Having A Passive Non-Contacting Bearing Suspension | |
| RU2567822C2 (en) | Blood pump with rotor | |
| Mitamura et al. | A magnetic fluid seal for rotary blood pumps: Behaviors of magnetic fluids in a magnetic fluid seal | |
| JP2009254436A (en) | Artificial heart pump equipped with dynamic pressure bearing | |
| Thamsen et al. | Investigation of the axial gap clearance in a hydrodynamic‐passive magnetically levitated rotary blood pump using X‐ray radiography | |
| Mitamura et al. | Development of the valvo pump: an axial flow pump implanted at the heart valve position | |
| JP2022522091A (en) | HVAD cleaning through non-uniform thrust bearing gaps | |
| Kosaka et al. | Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis | |
| Yamane et al. | Enhancement of hemocompatibility of the MERA monopivot centrifugal pump: toward medium‐term use | |
| Kosaka et al. | Optimal bearing gap of a multiarc radial bearing in a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis | |
| JP6646296B2 (en) | How the blood pump works | |
| Sakota et al. | Feasibility of the optical imaging of thrombus formation in a rotary blood pump by near‐infrared light | |
| Li et al. | Artificial Heart Based on Electrically Controlled Non‐Toxic Liquid Metal Pump | |
| Yasui et al. | Optimal design of the hydrodynamic multi‐arc bearing in a centrifugal blood pump for the improvement of bearing stiffness and hemolysis level | |
| Murashige et al. | Evaluation of a spiral groove geometry for improvement of hemolysis level in a hydrodynamically levitated centrifugal blood pump | |
| Shu et al. | Experimental Study of Micro‐Scale Taylor Vortices Within a Co‐Axial Mixed‐Flow Blood Pump | |
| US11519413B2 (en) | Optimizing pumping of variable viscosities via microtextured miniaturized tesla pump | |
| Kosaka et al. | Effect of a bearing gap on hemolytic property in a hydrodynamically levitated centrifugal blood pump with a semi-open impeller | |
| JP5828459B2 (en) | Centrifugal blood pump | |
| Murashige et al. | Evaluation of erythrocyte flow at a bearing gap in a hydrodynamically levitated centrifugal blood pump | |
| Locke et al. | Testing of a centrifugal blood pump with a high efficiency hybrid magnetic bearing | |
| Miller et al. | A preliminary flow visualization study in a multiple disk centrifugal artificial ventricle |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20180531 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20190228 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20190319 |
|
| A601 | Written request for extension of time |
Free format text: JAPANESE INTERMEDIATE CODE: A601 Effective date: 20190515 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20190701 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20191009 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20191204 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20191225 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20191226 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6646296 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |