JP4081921B2

JP4081921B2 - Electronic blood pressure monitor

Info

Publication number: JP4081921B2
Application number: JP14793199A
Authority: JP
Inventors: 義明渡邊; 靖之金澤; 誠澁谷
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1999-05-27
Filing date: 1999-05-27
Publication date: 2008-04-30
Anticipated expiration: 2019-05-27
Also published as: JP2000333915A

Description

【０００１】
【発明の属する技術分野】
本発明は、人体の血圧を測定する血圧計に関するものであり、特に自動で非観血的に測定する電子血圧計に関するものである。
【０００２】
【従来の技術】
従来のこの種の電子血圧計は、腕や手首にカフを巻き付けカフに最高血圧以上の圧力を加えて血流を一時的に阻害した後に、徐々にカフの圧力を下げその過程で脈音が発生する時点と消失する時点の圧力から最高血圧値と最低血圧値を決定するコロトコフ音法や、同じくカフ圧の減圧過程における心拍に同期して発生するカフの微小な圧力変動の振幅の変化を用いて血圧値を決定するオシロメトリック法を用いて人体の血圧を決定するものが多かった。
【０００３】
オシロメトリック法について図面を用いて説明する。図６(a)にカフの圧力変化、図６(b)に(a)の圧力変化からDC成分をカットして心臓の活動に伴なって発生する脈波に変換し、さらに、心臓の活動の一拍毎の振幅を算出した波形をそれぞれ示す。図６(a)に示すように、まずカフを最高血圧(SBP)以上に加圧し、そこから徐々に減圧していくと、図のように心臓の活動に起因する微小な圧力変化が現れるが、この微少な圧力変化のＤＣ成分をカットして得られる脈波の振幅はカフ圧によって図６(b)のように変化する。カフの圧力を最高血圧以上の圧力から徐々に減圧していくと脈波の振幅は初めは増加していくが、これがある時点でピークを迎えた後は一転してカフの圧力の減少と共に振幅も減少していく。このカフの圧力と脈波の振幅の関係は人体の血圧値と強い相関があることが分かっており、統計的な調査の結果から、図６(b)のように、振幅が最大の時点より高いカフ圧において最大振幅に対してある割合の高さRhになる時点のカフの圧力値から最高血圧(SBP)を、さらに、最大振幅より低いカフ圧において最大振幅に対してある割合の高さRlになる時点のカフの圧力値から最低血圧(DBP)を決定している。なお、最高血圧や最低血圧を決定する際の最大振幅に対する割合は統計的に決定され、最高血圧では40%〜70%、最低血圧は50%〜80%が用いられる事が多い。
【０００４】
さらに、これらの方法の測定精度向上を図るため、例えば、特開平３−１５１９３３号公報に記載されている電子血圧計では、上記のオシロメトリック法による血圧決定法に加え、カフ内の微小な圧力変化から得られる脈波の波形を用い、脈波の平坦部分を抽出して減圧測定において平坦部分が消失する点あるいは加圧測定において平坦部分が出現する点を最低血圧と決定している。この最低血圧の決定は、カフ圧が最高血圧よりも大きい場合は、血管が圧平されており（押し潰されており）、その区間は血管容積に変化がなく、心臓拡張期で脈波に変化のない部分（平坦部分）が生じ、また、カフ圧が最高血圧と最低血圧との間にある場合は、区間的にカフ圧より血管内圧が低いところがあり、そこでは血管が圧平されて脈波が平坦になり、更に、カフ圧が低くなり、最低血圧以下になると、血管はいずれの区間においても全く圧平されず、脈波の平坦部分は消失するというカフ圧の変化に伴ない発生する脈波の変化を用いて行っている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記従来の電子血圧計では、カフの減圧過程において脈音や圧力変動の振幅の変化、平坦部分の消失あるいは出現時点を用いているが、これらの変化はカフ圧の変化とは比例関係にはなく、従って、より正確な測定を行うためには減圧速度を下げてより多くのカフ圧に対し脈音や脈波を採取する必要があり、そのため、測定精度を維持したまま測定にかかる時間を短縮する事が困難であるという課題があった。
【０００６】
【課題を解決するための手段】
本発明は上記課題を解決するため、人体の四肢に装着され内部の圧力変化によって装着部位の血液流動を阻害する加圧手段と、前記加圧手段に圧力を加える圧力発生手段と、前記加圧手段の圧力を徐々に減圧する微速排気弁と、前記加圧手段の圧力を検出する圧力検出手段と、前記加圧手段の近傍もしくは加圧手段より末梢側において心臓の活動によって生ずる脈波を検出する脈波検出手段と、脈波検出手段の出力波形から特徴となるパラメータを算出して出力する特徴値算出手段と、前記特徴値算出手段の出力と前記圧力検出手段の出力とにより前記人体の血圧値を決定する血圧値決定手段とからなり、前記特徴値算出手段は前記脈波検出手段の出力を心拍の一拍毎の波形に分割する波形分割手段と、前記波形分割手段により分割された波形の振幅を算出する振幅算出手段と、前記波形分割手段により分割された波形を前記振幅算出手段の出力で正規化して出力する波形正規化手段と、前記波形正規化手段の出力波形があらかじめ決められた値以上となる時間を算出する時間測定手段とを持ち、前記血圧値決定手段では前記特徴値算出手段の時間測定手段の出力の変化の開始点および終了点と圧力検出手段の出力とから前記人体の血圧値を決定するものである。
【０００７】
上記発明によれば、時間測定手段の出力が、カフ圧が最高血圧と最低血圧の間にある時はカフ圧とほぼ比例関係にあり最高血圧以上あるいは最低血圧以下でははほとんど変化しないことを用いて、時間測定手段の出力の変化の開始点と終了点を求めて血圧値を算出するので、血圧値の算出に必要とするカフ圧と時間のデータ数を削減する事ができ、短い測定時間で正確な血圧を測定できる電子血圧計を提供できる。
【０００８】
【発明の実施の形態】
本発明の請求項１にかかる電子血圧計は、人体の四肢に装着され内部の圧力変化によって装着部位の血液流動を阻害する加圧手段と、前記加圧手段に圧力を加える圧力発生手段と、前記加圧手段の圧力を徐々に減圧する微速排気弁と、前記加圧手段の圧力を検出する圧力検出手段と、前記加圧手段の近傍もしくは加圧手段より末梢側において心臓の活動によって生ずる脈波を検出する脈波検出手段と、脈波検出手段の出力波形から特徴となるパラメータを算出して出力する特徴値算出手段と、前記特徴値算出手段の出力と前記圧力検出手段の出力とにより前記人体の血圧値を決定する血圧値決定手段とからなり、前記特徴値算出手段は前記脈波検出手段の出力を心拍の一拍毎の波形に分割する波形分割手段と、前記波形分割手段により分割された波形の振幅を算出する振幅算出手段と、前記波形分割手段により分割された波形を前記振幅算出手段の出力で正規化して出力する波形正規化手段と、前記波形正規化手段の出力波形があらかじめ決められた値以上となる時間を算出する時間測定手段とを持ち、前記血圧値決定手段では前記特徴値算出手段の時間測定手段の出力の変化の開始点および終了点と圧力検出手段の出力とから前記人体の血圧値を決定する。
【０００９】
そして、時間測定手段の出力が、カフ圧が最高血圧と最低血圧の間にある時はカフ圧とほぼ比例関係にあり最高血圧以上あるいは最低血圧以下でははほとんど変化しないことを用いて、時間測定手段の出力の変化の開始点と終了点を求めて血圧値を算出するので、血圧値の算出に必要とするカフ圧と時間のデータ数を削減する事ができ、短い測定時間で正確な血圧を測定できる。
【００１０】
本発明の請求項２にかかる電子血圧計は特徴値算出手段は時間測定手段を複数持ち、波形正規化手段の出力波形がそれぞれ異なる値以上となる時間を測定して出力し、血圧値決定手段はこれら複数の時間測定手段の出力から人体の血圧値を決定する。
【００１１】
そして、採取された脈波から複数の時間測定手段の複数の出力を用いて人体の血圧を決定するので、さらに短い測定時間で正確な血圧測定を実現できる。
【００１６】
本発明の請求項３にかかる電子血圧計は、振幅算出手段は、波形分割手段の出力波形の最小値或いは最大値とその前後の値の少なくとも3点以上から決定される近似曲線を求めその最小値或いは最大値から両者の差を算出して出力する。
【００１７】
そして、波形分割手段の分割した波形を正規化するために用いる振幅を算出する際に様々な誤差の影響を排除できるので、時間測定手段の測定精度を向上させることができ、従って、さらに短い測定時間で正確な血圧測定を実現できる。
【００２０】
【実施例】
以下、本発明の実施例について図面を用いて説明する。
【００２１】
（実施例１）
図１は本発明の実施例１における電子血圧計のブロック図、図２は波形正規化手段の出力と時間測定手段の測定する時間を示す波形図である。なお、本実施例の血圧計は人体の上腕部をカフを用いて加圧する上腕式電子血圧計の例を示す。図１において、１は人体の上腕を加圧する圧力印加手段であるカフ、２はカフ１に圧力を供給する加圧手段である加圧ポンプ、３はカフ２の圧力を徐々に減圧する微速排気弁、４は測定終了時や異常時に急速に開放しカフ圧を大気圧に戻す急速排気弁、５はカフ１内の圧力検出手段である圧力センサ、６は圧力センサ５の出力信号からDC成分をカットし心臓の活動に同期した微小な圧力変化を示す脈波を抽出して出力する脈波検出手段、７は脈波検出手段６が検出した脈波から血圧値算出に用いる特徴値を算出する特徴値算出手段、８は圧力センサ５の出力と特徴値算出手段７の出力とから人体の血圧値を決定する血圧値決定手段であり、また、これらの制御を司る制御手段９と測定の開始を指示するスタートボタン１０、測定結果を表示するＬＣＤからなる表示手段１１である。これらのうちカフ１、加圧ポンプ２、微速排気弁３および急速排気弁４はゴム管１２により空気圧がもれないように接続されている。さらに、特徴値検出手段７は脈波検出手段６の出力を心拍の1周期毎の波形に分割する波形分割手段１３と、波形分割手段１３の出力信号の振幅を算出する振幅算出手段１４と、波形分割手段１３の出力信号を振幅算出手段１４が算出した振幅を用いて正規化して出力する波形正規化手段１５と、波形正規化手段１５の出力波形があらかじめ決められた値以上となる時間を算出する時間測定手段１６とからなり、時間測定手段１６の出力信号が血圧値決定手段８に出力される。
【００２２】
次に動作、作用について説明する。血圧を測定する人体がカフ１を上腕の周囲に巻きつけスタートボタン１０を押すと、制御手段９が加圧ポンプ２を動作させ、発生した圧力がゴム管１２を通じてカフ１に供給されてカフ１が巻き付けられた人体の上腕部を加圧する。この時、制御手段９は圧力センサ５の出力をモニターし、カフ１の圧力が人体の最高血圧値より高くなるようにあらかじめ決められた加圧目標値を越えた場合に加圧ポンプ２の動作を停止して加圧を止め、微速排気弁３によりカフ１の圧力を徐々に減圧していく減圧動作に移行する。この時、圧力センサ５の出力には心臓の活動による血管の振動がカフ１に伝達されるため微小な圧力変化が現れ、脈波検出手段６が圧力センサ５の信号からDC成分を除去し脈動成分のみを取り出して脈波を抽出し特徴値算出手段７に出力している。特徴値算出手段７では、まず波形分割手段１３が脈波検出手段６の検出した脈波を心臓の１拍毎の波形に分割し、振幅算出手段１４が波形分割手段１３により心臓の１拍毎の波形に分割された各波形の振幅を算出し、波形正規化手段１５が波形分割手段１３の出力波形を振幅算出手段１４の算出した振幅で除して正規化し、時間測定手段１６に出力している。時間測定手段１６では、以下に示すようなカフ１の圧力と血圧値との大小関係により変化する波形正規化手段１５の出力波形の変化を捉え、血圧値決定手段８に出力している。すなわち、カフ１の圧力が最高血圧以上の時は、カフ１の巻かれた上腕の血管は最高血圧より高い圧力で押さえられて完全に押しつぶされてしまうため血液が流れず、カフ１の圧力の微小な変動である脈波も図２(a)に示すような血管の心臓側から受ける圧力波のみによる鋭角的な波形を示す。次に、カフ１の圧力が最高血圧以下になると、カフ１の圧力が血圧より低い時間だけ血管に血液が流れ、この時の血液の体積分カフ１が圧迫されるため図２(b)に示すように血管に血液が流れる時間すなわち血圧よりカフ１の圧力が低い時間の長さに応じて脈波の最大値付近の波形が広がった波形となっていく。このような波形の変化はカフ１の圧力が低下し、カフ１直下の血管に血液が流れる時間の延長にしたがって広がってゆくが、カフ１の圧力が最低血圧以下になると常に血管に血液が流れるため図２(c)に示すように波形の最大値から直線的になだらかに減少する波形となり、カフ1の圧力が変化しても波形はほとんど変化しなくなる。本実施例では、時間測定手段１６がこのような波形の変化を振り幅の60％の高さ以上となる時間Ｔを測定して出力している。図3(a)に時間測定手段１６の出力とカフ圧の関係図を示す。最高血圧(SBP)以上ではほぼ一定でわずかにカフ１の圧力の低下に伴って小さくなる傾向があるが、SBP以下になるとカフ１の圧力の低下と共に急激に時間が長くなり最低血圧(図中DBP)以下になると時間の増加は止まりカフ１の圧力が低下してもほとんど変化がない。本実施例では、このような時間測定手段１６の出力を、カフ１の圧力が高く時間測定手段１６の出力の変動が少ないグループA、カフ１の圧力の変化に伴って時間測定手段１６の出力値が長くなるように変化しているグループB、カフ１の圧力が低く時間測定手段１６の出力の変動が少ないグループCの3つに分類し、それぞれについてカフ１の圧力と時間測定手段１６の出力との回帰直線を求め、Aの直線とBの直線の交点となるカフ１の圧力を最高血圧、Bの直線とCの直線の交点となるカフ１の圧力を最低血圧として表示器１１に出力している。
【００２３】
図３(a)では従来の血圧計のようにゆっくりと減圧してカフ１の圧力の最大値から人体の最低血圧以下となるまで16点のカフ１の圧力と時間測定手段１６の出力とで最高血圧と最低血圧を決定した例を示したが、図3(b)ではカフの減圧速度を図3(a)の倍に設定し、データを半数の8点とした場合を示している。図のようにA,B,Cの3本の直線はほとんど変化せず、従って、算出される最高血圧と最低血圧もほとんど変化しない。すなわち、従来の血圧計のように減圧速度を上げても精度の低下が少なく、測定精度を低下させることなく測定時間の短縮を実現する事が可能である。
【００２４】
血圧値決定手段８では、上記に示す方法を用いて人体の最高血圧と最低血圧を決定して制御手段9に出力し、制御手段９は血圧値を表示手段１１に表示させると共に、急速排気弁４を開放しカフ１の圧力を大気圧まで急速に低下させ、測定終了を人体に知らせている。
【００２５】
上記のように、本実施例の電子血圧計は、カフ１の圧力と血圧値との大小関係に応じて変化する脈波波形の特徴を時間測定手段１６で抽出し、圧力センサ５の出力と、時間測定手段１６の出力とから人体の血圧値を決定するので、測定精度を低下させることなく測定時間の短縮を実現することができる。
【００２６】
なお、本実施例では、時間測定手段１６が波形正規化手段１５の出力波形における振幅の６０％を越える時間を計測して出力しているが、３０％〜８０％の高さの範囲なら同様な処理が可能である。ただし、振り幅の４０％〜７０％が精度の面でより望ましい。
【００２７】
また、本実施例では時間測定手段を一つ設けているが、複数の時間測定手段を設けそれぞれ異なる高さ以上となる時間を測定し、これらの複数の測定結果を用いて血圧の決定をしてもよい。この場合、測定精度を更に上げる事が可能となり、結果として測定時間を更に短縮する事も可能となる。
【００２８】
また、本実施例では振幅算出手段が波形分割手段により分割された各波形の振り幅を算出する際、単純に最小値と最大値の差を取るのではなく、最大値或いは最小値とその前後0.025秒間の計0.05秒間の波形データを用い、これらの波形データから２次の多項式による近似曲線を求め、その極大値或いは極小値の差から振幅を求めている。これによりノイズの影響を受けずに正確な振幅を算出でき、時間測定手段の測定時間の精度も向上させる事ができる。なお、ここでは近似式作成に用いるデータを最大値或いは最小値を中心とする0.05秒間の波形データを用い2次の多項式近似曲線を求めているが、時間幅やデータ数は少なくとも最大値又は最小値を含みその前後の点を含んでおれば算出は可能で、近似式の形式も他に適当なものがあれば適宜選択して用いればよく、これらを限定する事を発明の趣旨とするものではない。
【００２９】
また、本実施例では人体の上腕にカフを巻きつけて血圧を測定する上腕式血圧計に適用した例を示しているが、手首や指、又は上肢に限らず太股や足首など下肢で血圧を測定する血圧計でも同じ効果が得られる。
【００３０】
また、本実施例ではカフ１の圧力の微小な圧力変動から脈波を採取しているが、血液による光の吸収を利用した光電脈波や皮膚表面の振動を振動センサで採取する圧脈波を採取して血圧を算出してもよい。
【００３１】
また、本実施例では、時間測定手段１６の出力と圧力測定手段５の出力を３グループに分けそれぞれの近似直線を求めることによって血圧値を決定しているが、グループ分けをせずすべての点から近似曲線を求めてその変極点等の曲線の式から算術的に求められる値から血圧値を決定する構成でもよい。
【００３２】
さらに、本実施例では時間計測手段１６の出力と圧力センサ５の出力のみで人体の血圧値を決定しているが、振幅算出手段１４の出力する脈波の振幅の変化を用いてオシロメトリック法による血圧値算出も合わせて行い、両者の結果を併記したり、両者の平均を持って血圧値として決定してもよく、これにより、ばらつきをおさえることができる。さらに、両者の血圧値が大きく異なっていた場合は、脈波波形の採取時に人体に体動が発生した場合などの大きなノイズ等が混入した場合と考えられるので、それを報知したり再度測定し直すように促すような表示をしてもよい。
【００３３】
また、表示器１１は装置に直接取り付けられる必要はなく、制御手段９が有線又は無線通信により他の機器に血圧値を送信し、そちらで表示させた記憶された過去の血圧値と共に表示してその推移を確認できるようにするなどしてもよい。
【００３４】
また、微速排気弁３は排気速度が加圧ポンプによる加圧速度より十分遅い場合は、制御手段９による制御を受けずカフ１に圧力が加えられている時は常に一定の速度で空気を排気する構成でもよい。
【００３５】
（実施例２）
図４は本発明の実施例２の電子血圧計のブロック図、図５は波形正規化手段の出力と時間測定手段および増加時間測定手段の測定する時間を示す波形図である。
【００３６】
本実施例２において、実施例１と異なる点は時間計測手段１６の他に増加時間計測手段１７を持ち、血圧値決定手段８では時間計測手段１６の出力と増加時間測定手段17の出力と圧力センサ５の出力とから人体の血圧値を算出する点にある。
【００３７】
なお、実施例１と同一符号のものは同一構造を有し、説明は省略する。
【００３８】
次に動作、作用を説明する。図５は波形正規化手段の出力で図５(a)はカフ１の圧力が最高血圧以上でカフ１直下にある血管が押しつぶされて血液が全く流れない状態、図５(b)はカフ１の圧力が最高血圧から最低血圧の間にあり、カフ１の圧力が血圧より低い時に限りカフ１直下にある血管に血液が流れる状態、図５(c)はカフ１の圧力が最低血圧以下でカフ直下にある血管に常に血液が流れている状態である。これを見ると図2と同様、カフ１の圧力が徐々に低下して血管に血液が流れる時間が多くなると共に振幅の６０％以上となる時間は増加しているが、Tupで示される波形の最小値から最大値に至るまでに経過する時間もわずかながら増加する傾向にある。この増加もＴと同様にカフ１の圧力とは比較的比例関係に近く、この値を時間測定手段１６の出力の値に加えて用いる事によってさらに血圧値の測定精度を向上させる事が出来る。本実施例では増加時間測定手段１７によりTupの値を測定して血圧値決定手段８に出力し、血圧値決定手段８では増加時間算出手段１７の出力と時間測定手段１６の出力との二乗和を算出して血圧値決定に用いている。この算出結果を用いて血圧値を決定するための血圧値決定手段8における処理は実施例1とほとんど同様であるが、上記処理により出力値からノイズの影響を減ずる事ができ、さらに精度のよい血圧値決定や測定時間の短縮を図る事が可能となる。
【００３９】
上記に示すように本発明の電子血圧計は、精度の低下を起こす事なく従来よりも短時間で測定できるので、カフの加圧による圧迫感を減じる事ができ、手軽に計測できる電子血圧計を提供できる。
【００４０】
【発明の効果】
以上説明したように本発明の請求項１に係る電子血圧計は、時間測定手段が測定する時間が、カフ圧が最高血圧と最低血圧の間にある時はカフ圧とほぼ比例関係にあり最高血圧以上あるいは最低血圧以下でははほとんど変化しないことを用いて、時間の変化の開始点と終了点を求めて血圧値を算出するので、血圧値の算出に必要とするカフ圧と時間のデータ数を削減する事ができ、短い測定時間で正確な血圧を測定できるという効果がある。
【００４１】
また、請求項２に係る電子血圧計は、採取された脈波から複数の時間測定手段が測定した複数の時間を用いて人体の血圧を決定するので、さらに短い測定時間で正確な血圧測定を実現できるという効果がある。
【００４４】
また、請求項３に係る電子血圧計は、波形分割手段の分割した波形を正規化するために用いる振幅を算出する際に様々な誤差の影響を排除できるので、時間測定手段の測定精度を向上させることができ、従って、さらに短い測定時間で正確な血圧測定を実現できるという効果がある。
【図面の簡単な説明】
【図１】本発明の実施例１における電子血圧計のブロック図
【図２】（ａ）同電子血圧計の波形正規化手段のカフの圧力が最高血圧以上の場合の出力波形図
（ｂ）同電子血圧計の波形正規化手段のカフの圧力が最高血圧以下かつ最低血圧以上の場合の出力波形図
（ｃ）同電子血圧計の波形正規化手段のカフの圧力が最低血圧以下の場合の出力波形図
【図３】同電子血圧計の圧力センサの値に対する時間測定手段の出力図
【図４】本発明の実施例２における電子血圧計のブロック図
【図５】（ａ）同電子血圧計の波形正規化手段のカフの圧力が最高血圧以上の場合の出力波形図
（ｂ）同電子血圧計の波形正規化手段のカフの圧力が最高血圧以下かつ最低血圧以上の場合の出力波形図
（ｃ）同電子血圧計の波形正規化手段のカフの圧力が最低血圧以下の場合の出力波形図
【図６】（ａ）従来の電子血圧計のオシロメトリック法による血圧値決定法の説明図
（ｂ）従来の電子血圧計のオシロメトリック法による血圧値決定法の説明図
【符号の説明】
１カフ（圧力印加手段）
２加圧ポンプ（加圧手段）
３微速排気弁
５圧力センサ（圧力検出手段）
６脈波検出手段
７特徴値算出手段
８血圧値決定手段
１３波形分割手段
１４振幅算出手段
１５波形正規化手段
１６時間測定手段
１７増加時間測定手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sphygmomanometer that measures the blood pressure of a human body, and more particularly to an electronic sphygmomanometer that automatically and noninvasively measures blood pressure.
[0002]
[Prior art]
This type of conventional electronic blood pressure monitor wraps the cuff around the wrist or wrist, applies pressure above the maximum blood pressure to the cuff and temporarily impedes blood flow, then gradually lowers the cuff pressure and makes a pulse sound in the process The Korotkoff sound method, which determines the systolic blood pressure and the systolic blood pressure from the pressure at the time of occurrence and the time of disappearance, and the change in the amplitude of the minute pressure fluctuation of the cuff that occurs in synchronization with the heartbeat in the decompression process of the cuff pressure. Many have used the oscillometric method to determine blood pressure using the oscillometric method.
[0003]
The oscillometric method will be described with reference to the drawings. Fig. 6 (a) shows the change in cuff pressure, Fig. 6 (b) shows that the DC component is cut from the pressure change in (a) and converted into a pulse wave generated by the heart activity. The waveform which calculated the amplitude for every beat is shown, respectively. As shown in Fig. 6 (a), when the cuff is first pressurized above the systolic blood pressure (SBP) and then gradually depressurized, a slight pressure change due to the heart activity appears as shown in the figure. The amplitude of the pulse wave obtained by cutting the DC component of this slight pressure change changes as shown in FIG. 6B depending on the cuff pressure. When the cuff pressure is gradually reduced from the pressure higher than the maximum blood pressure, the amplitude of the pulse wave initially increases, but after reaching a peak at a certain point, the amplitude changes as the cuff pressure decreases. Will also decrease. It is known that the relationship between the cuff pressure and the amplitude of the pulse wave has a strong correlation with the blood pressure value of the human body. From the results of statistical investigations, as shown in FIG. The systolic blood pressure (SBP) is calculated from the pressure value of the cuff at a certain height Rh with respect to the maximum amplitude at a high cuff pressure, and a certain height with respect to the maximum amplitude at a cuff pressure lower than the maximum amplitude. The diastolic blood pressure (DBP) is determined from the pressure value of the cuff at the time of Rl. Note that the ratio of the maximum blood pressure and the minimum blood pressure when determining the maximum blood pressure is statistically determined, and 40% to 70% is often used for the maximum blood pressure, and 50% to 80% is often used for the minimum blood pressure.
[0004]
Furthermore, in order to improve the measurement accuracy of these methods, for example, in an electronic sphygmomanometer described in JP-A-3-151933, in addition to the blood pressure determination method by the oscillometric method, a minute pressure in the cuff Using the waveform of the pulse wave obtained from the change, the flat part of the pulse wave is extracted and the point where the flat part disappears in the decompression measurement or the point where the flat part appears in the pressurization measurement is determined as the minimum blood pressure. In determining the minimum blood pressure, when the cuff pressure is greater than the maximum blood pressure, the blood vessel is flattened (squeezed), the blood vessel volume does not change in that section, and the pulse wave is detected during diastole. When there is a part that does not change (flat part), and the cuff pressure is between the highest and lowest blood pressures, there is a section where the intravascular pressure is lower than the cuff pressure, where the blood vessels are applanated. When the pulse wave becomes flat, and when the cuff pressure becomes lower and lower than the minimum blood pressure, the blood vessel is not applanated in any section, and the flat part of the pulse wave disappears, accompanying the change in cuff pressure. This is done using changes in the generated pulse wave.
[0005]
[Problems to be solved by the invention]
However, the conventional electronic sphygmomanometer uses the change in the amplitude of the pulse sound and pressure fluctuation, the disappearance of the flat portion, or the current point in time during the cuff decompression process, and these changes are proportional to the cuff pressure change. Therefore, in order to perform a more accurate measurement, it is necessary to reduce the decompression speed and collect pulse sounds and pulse waves for more cuff pressures. Therefore, measurement is performed while maintaining measurement accuracy. There was a problem that it was difficult to shorten the time.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a pressurizing unit that is mounted on the extremity of a human body and inhibits blood flow in the mounting site due to a change in internal pressure, a pressure generating unit that applies pressure to the pressurizing unit, A slow exhaust valve for gradually reducing the pressure of the means, a pressure detecting means for detecting the pressure of the pressurizing means, and a pulse wave generated by the activity of the heart in the vicinity of the pressurizing means or on the distal side of the pressurizing means. A pulse wave detecting means, a characteristic value calculating means for calculating and outputting a characteristic parameter from an output waveform of the pulse wave detecting means, an output of the characteristic value calculating means, and an output of the pressure detecting means. Blood pressure value determining means for determining a blood pressure value, wherein the feature value calculating means is divided by the waveform dividing means for dividing the output of the pulse wave detecting means into a waveform for each beat of the heartbeat, and the waveform dividing means. wave Amplitude calculating means for calculating the amplitude of the waveform, waveform normalizing means for normalizing and outputting the waveform divided by the waveform dividing means with the output of the amplitude calculating means, and the output waveform of the waveform normalizing means are predetermined. A time measuring means for calculating a time that is equal to or greater than the above value, and the blood pressure value determining means is configured to determine the output from the start and end points of the change in the output of the time measuring means of the feature value calculating means and the output of the pressure detecting means. The blood pressure value of the human body is determined.
[0007]
According to the above invention, it is used that the output of the time measuring means is substantially proportional to the cuff pressure when the cuff pressure is between the maximum blood pressure and the minimum blood pressure, and hardly changes when the cuff pressure is above the maximum blood pressure or below the minimum blood pressure. Since the blood pressure value is calculated by obtaining the start and end points of the change in the output of the time measuring means, the number of cuff pressure and time data required for calculating the blood pressure value can be reduced, and the measurement time can be shortened. An electronic blood pressure monitor that can accurately measure blood pressure can be provided.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An electronic sphygmomanometer according to claim 1 of the present invention is a pressurizing unit that is worn on the extremities of a human body and that inhibits blood flow in the wearing site due to a change in internal pressure, a pressure generating unit that applies pressure to the pressurizing unit, A slow exhaust valve for gradually reducing the pressure of the pressurizing means, a pressure detecting means for detecting the pressure of the pressurizing means, and a pulse generated by the activity of the heart in the vicinity of the pressurizing means or on the peripheral side of the pressurizing means. A pulse wave detecting means for detecting a wave, a characteristic value calculating means for calculating and outputting a characteristic parameter from an output waveform of the pulse wave detecting means, an output of the characteristic value calculating means and an output of the pressure detecting means The blood pressure value determining means for determining the blood pressure value of the human body, wherein the feature value calculating means includes a waveform dividing means for dividing the output of the pulse wave detecting means into a waveform for each beat of the heartbeat, and the waveform dividing means. Split Amplitude calculating means for calculating the amplitude of the waveform, waveform normalizing means for normalizing and outputting the waveform divided by the waveform dividing means with the output of the amplitude calculating means, and the output waveform of the waveform normalizing means in advance A time measuring unit that calculates a time that is equal to or greater than a predetermined value, and the blood pressure value determining unit includes a start point and an end point of a change in the output of the time measuring unit of the feature value calculating unit, and an output of the pressure detecting unit. From the above, the blood pressure value of the human body is determined.
[0009]
The time measurement means that the output of the time measurement means is proportional to the cuff pressure when the cuff pressure is between the maximum blood pressure and the minimum blood pressure, and hardly changes below the maximum blood pressure or below the minimum blood pressure. Since the blood pressure value is calculated by obtaining the start point and end point of the change in the output of the means, the number of cuff pressure and time data required for calculating the blood pressure value can be reduced, and accurate blood pressure can be obtained in a short measurement time. Can be measured.
[0010]
The electronic sphygmomanometer according to claim 2 of the present invention has a plurality of time value measuring means as characteristic value calculating means, measures and outputs the time when the output waveform of the waveform normalizing means is different from each other, and outputs blood pressure value determining means. Determines the blood pressure value of the human body from the outputs of the plurality of time measuring means.
[0011]
And since the blood pressure of a human body is determined from the collected pulse waves using a plurality of outputs of a plurality of time measuring means, accurate blood pressure measurement can be realized in a shorter measurement time.
[0016]
In the electronic sphygmomanometer according to claim 3 of the present invention, the amplitude calculating means obtains an approximate curve determined from at least three points of the minimum value or the maximum value of the output waveform of the waveform dividing means and values before and after the minimum value. The difference between the two is calculated from the value or the maximum value and output.
[0017]
Since the influence of various errors can be eliminated when calculating the amplitude used for normalizing the divided waveform of the waveform dividing means, the measurement accuracy of the time measuring means can be improved, and therefore, even shorter measurement is possible. Realize accurate blood pressure measurement in time.
[0020]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
Example 1
FIG. 1 is a block diagram of an electronic sphygmomanometer in Embodiment 1 of the present invention, and FIG. 2 is a waveform diagram showing the output of a waveform normalizing means and the time measured by a time measuring means. The sphygmomanometer of the present embodiment is an example of an upper arm type electronic sphygmomanometer that pressurizes the upper arm of a human body using a cuff. In FIG. 1, 1 is a cuff which is a pressure applying means for pressurizing the upper arm of a human body, 2 is a pressurizing pump which is a pressurizing means for supplying pressure to the cuff 1, and 3 is a slow exhaust that gradually reduces the pressure of the cuff 2. Valve 4 is a quick exhaust valve that quickly opens to return the cuff pressure to atmospheric pressure at the end of measurement or when an abnormality occurs, 5 is a pressure sensor that is a pressure detection means in the cuff 1, and 6 is a DC component from the output signal of the pressure sensor 5 A pulse wave detecting means for extracting and outputting a pulse wave showing a minute pressure change synchronized with the activity of the heart, and 7 calculating a characteristic value used for blood pressure value calculation from the pulse wave detected by the pulse wave detecting means 6 The characteristic value calculating means 8 is a blood pressure value determining means for determining the blood pressure value of the human body from the output of the pressure sensor 5 and the output of the characteristic value calculating means 7, and the control means 9 for controlling these and the measurement means Start button 10 for instructing start, and display the measurement result A display unit 11 made of LCD. Among these, the cuff 1, the pressure pump 2, the slow exhaust valve 3, and the quick exhaust valve 4 are connected by a rubber tube 12 so that no air pressure is lost. Further, the feature value detecting means 7 is a waveform dividing means 13 for dividing the output of the pulse wave detecting means 6 into a waveform for each cycle of the heartbeat, an amplitude calculating means 14 for calculating the amplitude of the output signal of the waveform dividing means 13, A waveform normalizing unit 15 that normalizes and outputs the output signal of the waveform dividing unit 13 using the amplitude calculated by the amplitude calculating unit 14, and a time during which the output waveform of the waveform normalizing unit 15 is equal to or greater than a predetermined value. The time measuring means 16 to calculate is output, and the output signal of the time measuring means 16 is output to the blood pressure value determining means 8.
[0022]
Next, the operation and action will be described. When a human body for measuring blood pressure wraps the cuff 1 around the upper arm and presses the start button 10, the control means 9 operates the pressurizing pump 2, and the generated pressure is supplied to the cuff 1 through the rubber tube 12. Pressurizes the upper arm of the human body around which is wound. At this time, the control means 9 monitors the output of the pressure sensor 5, and when the pressure of the cuff 1 exceeds a predetermined pressure target value so as to be higher than the maximum blood pressure value of the human body, the operation of the pressure pump 2 is performed. Is stopped, the pressurization is stopped, and the operation proceeds to a pressure reducing operation in which the pressure of the cuff 1 is gradually reduced by the slow exhaust valve 3. At this time, since the vibration of the blood vessel due to the activity of the heart is transmitted to the cuff 1 at the output of the pressure sensor 5, a minute pressure change appears, and the pulse wave detecting means 6 removes the DC component from the signal of the pressure sensor 5 and pulsates. Only the components are extracted to extract the pulse wave and output to the feature value calculation means 7. In the feature value calculating means 7, the waveform dividing means 13 first divides the pulse wave detected by the pulse wave detecting means 6 into waveforms for each heart beat, and the amplitude calculating means 14 uses the waveform dividing means 13 for each heart beat. The waveform normalizing unit 15 normalizes the waveform divided by the amplitude calculated by the amplitude calculating unit 14 and outputs the result to the time measuring unit 16. ing. The time measuring unit 16 captures a change in the output waveform of the waveform normalizing unit 15 that changes depending on the magnitude relationship between the pressure of the cuff 1 and the blood pressure value as described below, and outputs the change to the blood pressure value determining unit 8. That is, when the pressure of the cuff 1 is equal to or higher than the maximum blood pressure, the blood vessel of the upper arm around which the cuff 1 is wound is pressed at a pressure higher than the maximum blood pressure and is completely crushed. The pulse wave which is a minute fluctuation also shows an acute waveform only by the pressure wave received from the heart side of the blood vessel as shown in FIG. Next, when the pressure of the cuff 1 falls below the maximum blood pressure, blood flows into the blood vessel only for a time when the pressure of the cuff 1 is lower than the blood pressure, and the volume cuff 1 of the blood at this time is compressed, so that FIG. As shown, the waveform in the vicinity of the maximum value of the pulse wave spreads according to the length of time during which the blood flows in the blood vessel, that is, the time during which the pressure of the cuff 1 is lower than the blood pressure. Such a change in the waveform reduces the pressure of the cuff 1 and spreads as the time for blood to flow to the blood vessel immediately below the cuff 1 increases. However, when the pressure of the cuff 1 falls below the minimum blood pressure, blood always flows through the blood vessel. Therefore, as shown in FIG. 2 (c), the waveform gradually decreases linearly from the maximum value of the waveform, and the waveform hardly changes even if the pressure of the cuff 1 changes. In this embodiment, the time measuring means 16 measures and outputs the time T when the change in the waveform is 60% or more of the width. FIG. 3 (a) shows the relationship between the output of the time measuring means 16 and the cuff pressure. Above the systolic blood pressure (SBP), it is almost constant and tends to decrease slightly as the pressure of the cuff 1 decreases. However, when the pressure falls below the SBP, the time rapidly increases as the pressure of the cuff 1 decreases and the systolic blood pressure (in the figure) Below DBP), the increase in time stops and there is almost no change even if the pressure of cuff 1 decreases. In this embodiment, the output of the time measuring means 16 is output from the time measuring means 16 as the pressure of the cuff 1 is changed in the group A in which the pressure of the cuff 1 is high and the output fluctuation of the time measuring means 16 is small. Group B is changed so as to increase in value, and Group C is a group C in which the pressure of the cuff 1 is low and output fluctuation of the time measuring means 16 is small. For each, the pressure of the cuff 1 and the time measuring means 16 The regression line with the output is obtained, and the pressure on the cuff 1 which is the intersection of the straight line A and the straight line B is the maximum blood pressure, and the pressure of the cuff 1 which is the intersection of the straight line B and the straight line C is the minimum blood pressure. Output.
[0023]
In FIG. 3 (a), the pressure of the cuff 1 and the output of the time measuring means 16 are gradually reduced from the maximum value of the pressure of the cuff 1 to below the minimum blood pressure of the human body as in the conventional blood pressure monitor. Although an example in which the maximum blood pressure and the minimum blood pressure are determined is shown, FIG. 3 (b) shows a case where the cuff pressure reduction rate is set to double that of FIG. 3 (a) and the data is half of eight points. As shown in the figure, the three straight lines A, B, and C hardly change, and thus the calculated maximum blood pressure and minimum blood pressure hardly change. In other words, even if the decompression speed is increased as in the conventional sphygmomanometer, the decrease in accuracy is small, and the measurement time can be shortened without reducing the measurement accuracy.
[0024]
The blood pressure value determining means 8 determines the maximum blood pressure and the minimum blood pressure of the human body using the method described above, and outputs them to the control means 9. The control means 9 displays the blood pressure values on the display means 11 and the quick exhaust valve. 4 is opened and the pressure of the cuff 1 is rapidly reduced to the atmospheric pressure to notify the human body of the end of the measurement.
[0025]
As described above, the electronic sphygmomanometer of the present embodiment extracts the characteristics of the pulse wave waveform that changes according to the magnitude relationship between the pressure of the cuff 1 and the blood pressure value by the time measuring means 16, and outputs the output of the pressure sensor 5. Since the blood pressure value of the human body is determined from the output of the time measuring means 16, the measurement time can be shortened without reducing the measurement accuracy.
[0026]
In this embodiment, the time measuring means 16 measures and outputs a time exceeding 60% of the amplitude in the output waveform of the waveform normalizing means 15, but it is the same if it is in the range of 30% to 80%. Processing is possible. However, 40% to 70% of the swing width is more desirable in terms of accuracy.
[0027]
In this embodiment, one time measuring means is provided, but a plurality of time measuring means are provided to measure the time when the heights are different from each other, and the blood pressure is determined using the plurality of measurement results. May be. In this case, the measurement accuracy can be further increased, and as a result, the measurement time can be further shortened.
[0028]
Further, in this embodiment, when the amplitude calculating means calculates the amplitude of each waveform divided by the waveform dividing means, it does not simply take the difference between the minimum value and the maximum value, but the maximum value or the minimum value and its front and back. Using waveform data for a total of 0.05 seconds for 0.025 seconds, an approximate curve by a second-order polynomial is obtained from these waveform data, and the amplitude is obtained from the difference between the maximum or minimum values. As a result, an accurate amplitude can be calculated without being affected by noise, and the accuracy of the measurement time of the time measuring means can be improved. Here, the data used for creating the approximate expression is obtained by using a 0.05 second waveform data centered on the maximum value or the minimum value, and a quadratic polynomial approximate curve is obtained, but the time width and the number of data are at least the maximum value or the minimum value. Calculation is possible if it includes a value and points before and after it, and if there are other appropriate types of approximate expression, they can be selected and used as appropriate, and the purpose of the invention is to limit these is not.
[0029]
Further, in this embodiment, an example is shown in which the present invention is applied to an upper arm sphygmomanometer that measures blood pressure by wrapping a cuff around the upper arm of a human body. The same effect can be obtained with a sphygmomanometer.
[0030]
In this embodiment, pulse waves are collected from minute pressure fluctuations in the pressure of the cuff 1, but photoelectric pulse waves using absorption of light by blood and pressure pulse waves for collecting vibrations on the skin surface with a vibration sensor. The blood pressure may be calculated by collecting the blood pressure.
[0031]
Further, in this embodiment, the blood pressure value is determined by dividing the output of the time measuring means 16 and the output of the pressure measuring means 5 into three groups and obtaining respective approximate lines, but all points are not divided into groups. Alternatively, the blood pressure value may be determined from a value that is obtained from an arithmetic curve from an equation of a curve such as an inflection point.
[0032]
Furthermore, in this embodiment, the blood pressure value of the human body is determined only by the output of the time measuring means 16 and the output of the pressure sensor 5, but the oscillometric method is used by using the change in the amplitude of the pulse wave output from the amplitude calculating means 14. The blood pressure value may be calculated together, and the results of both may be written together, or the average of both may be determined as the blood pressure value, thereby reducing variations. Furthermore, if the blood pressure values of the two are significantly different, it may be due to large noise or the like that has occurred in the human body during the collection of the pulse wave waveform. A display that prompts the user to correct it may be displayed.
[0033]
Further, the display 11 does not need to be directly attached to the apparatus, and the control means 9 transmits the blood pressure value to another device by wired or wireless communication, and displays it together with the stored past blood pressure value displayed there. It may be possible to check the transition.
[0034]
Further, when the exhaust speed of the slow exhaust valve 3 is sufficiently slower than the pressurizing speed by the pressurizing pump, the air is always exhausted at a constant speed when pressure is applied to the cuff 1 without being controlled by the control means 9. The structure to do may be sufficient.
[0035]
(Example 2)
FIG. 4 is a block diagram of an electronic sphygmomanometer according to the second embodiment of the present invention, and FIG. 5 is a waveform diagram showing the output of the waveform normalization means and the time measured by the time measurement means and the increase time measurement means.
[0036]
The second embodiment is different from the first embodiment in that it has an increase time measurement means 17 in addition to the time measurement means 16, and the blood pressure value determination means 8 outputs the output of the time measurement means 16, the output of the increase time measurement means 17, and the pressure. The blood pressure value of the human body is calculated from the output of the sensor 5.
[0037]
In addition, the thing of the same code | symbol as Example 1 has the same structure, and abbreviate | omits description.
[0038]
Next, the operation and action will be described. FIG. 5 shows the output of the waveform normalization means. FIG. 5A shows a state where the pressure of the cuff 1 is higher than the maximum blood pressure and the blood vessel just below the cuff 1 is crushed and no blood flows. FIG. When the pressure of the cuff 1 is between the maximum blood pressure and the minimum blood pressure, and the pressure of the cuff 1 is lower than the blood pressure, the blood flows through the blood vessel immediately below the cuff 1, FIG. 5 (c) shows that the pressure of the cuff 1 is below the minimum blood pressure. The blood is always flowing in the blood vessel directly under the cuff. As shown in FIG. 2, the pressure of the cuff 1 gradually decreases and the time for blood to flow through the blood vessel increases and the time for the amplitude to exceed 60% increases, but the waveform shown by Tup increases. The time that elapses from the minimum value to the maximum value also tends to increase slightly. Like T, this increase is relatively close to the pressure of the cuff 1, and by using this value in addition to the output value of the time measuring means 16, the measurement accuracy of the blood pressure value can be further improved. In the present embodiment, the Tup value is measured by the increase time measuring means 17 and output to the blood pressure value determining means 8, and the blood pressure value determining means 8 is the sum of squares of the output of the increase time calculating means 17 and the output of the time measuring means 16. Is used to determine the blood pressure value. The processing in the blood pressure value determining means 8 for determining the blood pressure value using this calculation result is almost the same as in the first embodiment, but the above processing can reduce the influence of noise from the output value, and the accuracy is higher. It is possible to determine the blood pressure value and shorten the measurement time.
[0039]
As described above, the electronic sphygmomanometer of the present invention can measure in a shorter time than before without causing a decrease in accuracy, so that the electronic sphygmomanometer can reduce the feeling of pressure due to cuff pressurization and can be easily measured. Can provide.
[0040]
【The invention's effect】
As described above, in the electronic sphygmomanometer according to claim 1 of the present invention, the time measured by the time measuring means is approximately proportional to the cuff pressure when the cuff pressure is between the highest blood pressure and the lowest blood pressure. Since the blood pressure value is calculated by obtaining the start and end points of the change in time using the fact that there is little change above the hypertension or below the minimum blood pressure, the number of cuff pressure and time data required to calculate the blood pressure value There is an effect that accurate blood pressure can be measured in a short measurement time.
[0041]
The electronic sphygmomanometer according to claim 2 determines the blood pressure of the human body using a plurality of times measured by a plurality of time measuring means from the collected pulse wave, so that accurate blood pressure measurement can be performed in a shorter measurement time. There is an effect that it can be realized.
[0044]
The electronic sphygmomanometer according to claim 3 can eliminate the influence of various errors when calculating the amplitude used to normalize the waveform divided by the waveform dividing means, thereby improving the measurement accuracy of the time measuring means. Therefore, there is an effect that accurate blood pressure measurement can be realized in a shorter measurement time.
[Brief description of the drawings]
FIG. 1 is a block diagram of an electronic sphygmomanometer according to a first embodiment of the present invention. FIG. 2 (a) is an output waveform diagram when a cuff pressure of a waveform normalization means of the electronic sphygmomanometer is equal to or higher than a maximum blood pressure. Output waveform diagram when the cuff pressure of the waveform normalization means of the electronic sphygmomanometer is below the maximum blood pressure and above the minimum blood pressure (c) When the cuff pressure of the waveform normalization means of the electronic sphygmomanometer is below the minimum blood pressure FIG. 3 is an output waveform diagram. FIG. 4 is an output diagram of time measuring means with respect to the pressure sensor value of the electronic sphygmomanometer. FIG. 4 is a block diagram of the electronic sphygmomanometer in Embodiment 2 of the present invention. (B) An output waveform diagram when the cuff pressure of the waveform normalization means of the electronic blood pressure monitor is below the maximum blood pressure and above the minimum blood pressure. (C) The cuff pressure of the waveform normalization means of the electronic blood pressure monitor is the minimum blood pressure FIG. 6A is an explanatory diagram of a blood pressure value determining method by an oscillometric method of a conventional electronic sphygmomanometer. FIG. 6B is an explanatory diagram of a blood pressure value determining method by an oscillometric method of a conventional electronic sphygmomanometer. Figure [Explanation of symbols]
1 cuff (pressure application means)
2 Pressurizing pump (pressurizing means)
3 Slow exhaust valve 5 Pressure sensor (pressure detection means)
6 Pulse wave detecting means 7 Feature value calculating means 8 Blood pressure value determining means 13 Waveform dividing means 14 Amplitude calculating means 15 Waveform normalizing means 16 Time measuring means 17 Increase time measuring means

Claims

A pressurizing means that is attached to the extremities of the human body and inhibits blood flow at the attachment site by a change in internal pressure, a pressure generating means that applies pressure to the pressurizing means, and a slow exhaust that gradually reduces the pressure of the pressurizing means A valve, a pressure detecting means for detecting the pressure of the pressurizing means, a pulse wave detecting means for detecting a pulse wave generated by a heart activity in the vicinity of the pressurizing means or on the peripheral side of the pressurizing means, and a pulse wave detection Characteristic value calculating means for calculating and outputting a characteristic parameter from the output waveform of the means, blood pressure value determining means for determining the blood pressure value of the human body from the output of the characteristic value calculating means and the output of the pressure detecting means, The feature value calculating means comprises: a waveform dividing means for dividing the output of the pulse wave detecting means into a waveform for each beat of the heart; an amplitude calculating means for calculating the amplitude of the waveform divided by the waveform dividing means; Waveform normalizing means for normalizing and outputting the waveform divided by the waveform dividing means with the output of the amplitude calculating means, and time for calculating the time when the output waveform of the waveform normalizing means is a predetermined value or more An electronic sphygmomanometer that determines the blood pressure value of the human body from the start and end points of the change in the output of the time measuring means of the characteristic value calculating means and the output of the pressure detecting means in the blood pressure value determining means .

A pressurizing means that is attached to the extremities of the human body and inhibits blood flow at the attachment site by a change in internal pressure, a pressure generating means that applies pressure to the pressurizing means, and a slow exhaust that gradually reduces the pressure of the pressurizing means A valve, a pressure detecting means for detecting the pressure of the pressurizing means, a pulse wave detecting means for detecting a pulse wave generated by a heart activity in the vicinity of the pressurizing means or on the peripheral side of the pressurizing means, and a pulse wave detection Characteristic value calculating means for calculating and outputting a characteristic parameter from the output waveform of the means, blood pressure value determining means for determining the blood pressure value of the human body from the output of the characteristic value calculating means and the output of the pressure detecting means, The feature value calculating means comprises: a waveform dividing means for dividing the output of the pulse wave detecting means into a waveform for each beat of the heart; an amplitude calculating means for calculating the amplitude of the waveform divided by the waveform dividing means; Waveform normalizing means for normalizing and outputting the waveform divided by the waveform dividing means with the output of the amplitude calculating means, and time for calculating the time when the output waveform of the waveform normalizing means is a predetermined value or more An electronic sphygmomanometer that determines the blood pressure value of the human body from the output of the time measuring means of the characteristic value calculating means and the output of the pressure detecting means, wherein the blood pressure value determining means determines the blood pressure value of the human body. Has a plurality of time measuring means, and measures and outputs the time when the output waveform of the waveform normalizing means is different from each other, and the blood pressure value determining means includes the outputs of the plurality of time measuring means and the output of the pressure detecting means. The electronic blood pressure monitor according to claim 1, wherein the blood pressure value of the human body is determined from the above.

The amplitude calculation means obtains an approximate curve determined from at least three points of the minimum or maximum value of the output waveform of the waveform dividing means and the values before and after that, and calculates and outputs the difference between the two from the minimum or maximum value. The electronic sphygmomanometer according to any one of claims 1 to 2 .