人間のトランスヴェーノス・デフィブリレーションにおける強度と持続時間の関係に対する第2段階の持続時間の影響
1Department of Medicine, Division of Cardiology, University of Maryland School of Medicine, Baltimore, USA. sshorofs@medicine.umaryland.edu
Circulation
|November 1, 2000
まとめ
デフィブリレーションのための二相波形を最適化することが鍵です. 第2段階を2ミリ秒未満に短縮すると,ヒトにおける除細動値 (DFT) が著しく改善され,より長い期間はDFTに悪影響を及ぼさない.
科学分野:
- 心血管医学 心血管医学
- バイオメディカルエンジニアリング
- 電気生理学 電気生理学
背景:
- デフィブリレーションにおける二相波形効果の正確なメカニズムは,まだ完全に理解されていません.
- デフィブリレーションのための最適な二相波形構成は,現在進行中の議論の対象となっている.
- 動物の研究は,第2段階を第1段階を超えて延長すると,除細動の値 (DFT) が上昇する可能性があることを示しています.
研究 の 目的:
- ヒトの被験者における二相除細動波形の第2相における強度と持続間の関係を調査する.
- 第2段階の期間が異なる場合の,除細動の有効性への影響を判断する.
主な方法:
- 36人の患者を対象とした前向きなランダム化研究で,ダブルコイルの経静脈導管システムを使用した.
- 患者ごとに3つの除細動値 (DFT) が評価され,第2相の持続時間は1〜18 msに調整されました.
- 最初のフェーズの持続時間は,容量150マイクロファラードで6ミリ秒に固定されました.
主要な成果:
- DFTでの先端電圧の有意な上昇は,第2相パルス持続時間が1msに短縮された場合にのみ観察されました.
- DFTの電圧は,第2相の持続時間が2 msから18 msに延長された場合でも変わらなかった.
- 蓄積されたエネルギー,最先端電流,第2段階のエネルギーでも同様の傾向が見られたが,第2段階の持続時間が増加するにつれて,正規化された第2段階の電流は減少した.
結論:
- 人体では,二相除細動値 (DFT) の電圧とエネルギーは,第2相の持続時間が2 ms未満である場合にのみ改善されます.
- DFTの電圧は,第2相の持続時間の増加に対して無感性を示し,第1相の持続時間の3倍である18msまで増加します.
関連する概念動画
Time Course of Drug Effect
The progression of a drug's impact can be analyzed by examining both the concentration-time course and the effect-time course. The concentration-time course is determined by the drug's half-life and is influenced by factors such as its pharmacokinetics, including absorption, distribution, metabolism, and elimination. The effect of the drug is often related to its concentration in the plasma and is calculated using the maximum drug effect and the plasma concentration that generates 50 percent of...
Muscle Stimulation Frequency
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Fatigue
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
Fatigue Strength of Concrete
Fatigue, in the context of materials science and engineering, refers to the weakening or failure of a material caused by repeatedly applied loads, even if these loads are below the strength limit of the material. Fatigue strength in concrete is a critical property that influences its durability and longevity. Concrete can fail in two ways due to fatigue. Static fatigue or creep rupture occurs under a constant load or one that increases slowly. The other failure mode is due to cyclical or...
Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship
For drugs producing a quantal response, onset occurs when plasma concentration reaches a minimum effective level (Cmin). The drug's action duration depends on how long the plasma concentration remains above Cmin.Two primary factors influence this duration: dose size and the rate of drug removal from the action site. Both depend on the drug's redistribution to poorly perfused tissues and elimination processes. A larger dose promotes rapid onset and prolongs the effect's duration.Consider a...
Pharmacokinetic–Pharmacodynamic Relationship: Influence of Elimination Half-Life on Effect Duration
Drug elimination from the body primarily occurs through metabolic and excretion pathways. Hepatic metabolism transforms lipophilic drugs into hydrophilic forms for excretion, typically via enzymatic processes classified as phase I (modification) and phase II (conjugation). Renal excretion eliminates drugs and metabolites through filtration and secretion in the kidneys. Impairment in liver or kidney function can hinder these processes, delaying drug clearance and extending the drug’s half-life.


