From the Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts (M.J.P.); Department of Anesthesiology and Pain Medicine, Steward St. Elizabeth's Medical Center, Boston, Massachusetts (M.A.L., A.E.W., M.G.W., M.Y.M.); Division of Pulmonology, Department of Medicine, Steward St. Elizabeth's Medical Center, Boston, Massachusetts (H.T.); and Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (A.C.T., R.A.P.).
Anesthesiology. 2015 Mar;122(3):647-58. doi: 10.1097/ALN.0000000000000519.
Intravenous drug infusion driven by syringe pumps may lead to substantial temporal lags in achieving steady-state delivery at target levels when using very low flow rates ("microinfusion"). This study evaluated computer algorithms for reducing temporal lags via coordinated control of drug and carrier flows.
Novel computer control algorithms were developed based on mathematical models of fluid flow. Algorithm 1 controlled initiation of drug infusion and algorithm 2 controlled changes to ongoing steady-state infusions. These algorithms were tested in vitro and in vivo using typical high and low dead volume infusion system architectures. One syringe pump infused a carrier fluid and a second infused drug. Drug and carrier flowed together via a manifold through standard central venous catheters. Samples were collected in vitro for quantitative delivery analysis. Parameters including left ventricular max dP/dt were recorded in vivo.
Regulation by algorithm 1 reduced delivery delay in vitro during infusion initiation by 69% (low dead volume) and 78% (high dead volume). Algorithmic control in vivo measuring % change in max dP/dt showed similar results (55% for low dead volume and 64% for high dead volume). Algorithm 2 yielded greater precision in matching the magnitude and timing of intended changes in vivo and in vitro.
Compared with conventional methods, algorithm-based computer control of carrier and drug flows can improve drug delivery by pump-driven intravenous infusion to better match intent. For norepinephrine infusions, the amount of drug reaching the bloodstream per time appears to be a dominant factor in the hemodynamic response to infusion.
当使用非常低的流速（“微输注”）时，由注射器泵驱动的静脉内药物输注可能导致在达到目标水平的稳态输送时出现大量的时间滞后。本研究评估了通过药物和载体流的协调控制来减少时间滞后的计算机算法。
根据流体流动的数学模型开发了新的计算机控制算法。算法 1 控制药物输注的开始，算法 2 控制正在进行的稳态输注的变化。这些算法在体外和体内使用典型的高低死体积输注系统结构进行了测试。一台注射器泵输注载体液，另一台输注药物。药物和载体通过歧管一起通过标准中心静脉导管流动。体外收集样品进行定量输送分析。体内记录参数，包括左心室最大 dp/dt。
算法 1 在输注开始时减少了体外输送延迟，低死体积组减少了 69%，高死体积组减少了 78%。算法控制的体内测量%max dP/dt 的变化也显示出类似的结果（低死体积组为 55%，高死体积组为 64%）。算法 2 在体内和体外匹配预期变化的幅度和时间方面产生了更高的精度。
与传统方法相比，基于算法的载体和药物流的计算机控制可以通过泵驱动的静脉内输注来改善药物输送，以更好地匹配意图。对于去甲肾上腺素输注，单位时间内到达血流的药物量似乎是输注对血流动力学反应的主要因素。
