Department of Anesthesia, Ghent University Hospital, Belgium.
Br J Anaesth. 2010 Apr;104(4):452-8. doi: 10.1093/bja/aeq028. Epub 2010 Feb 26.
In the ideal pharmacokinetic-dynamic (PK-PD) model for calculating the predicted effect-site concentration of propofol (Ce(PROP)), for any Ce(PROP), the corresponding hypnotic effect should be constant. We compared three PK-PD models (Marsh PK with Shüttler PD, Schnider PK with fixed ke0, and Schnider PK with Minto PD) in their ability to maintain a constant bispectral index (BIS), while using the respective effect-site-controlled target-controlled infusion (TCI) algorithms.
We randomized 60 patients to Group M (Marsh's model with k(e0)=0.26 min(-1)), Group S1 or Group S2 (Schnider's model with a fixed k(e0)=0.456 min(-1) or a k(e0) adapted to a fixed time-to-peak effect=1.6 min, respectively). All patients received propofol at a constant rate until loss of consciousness. The corresponding Ce(PROP), as calculated by the respective models, was set as a target for effect-site-controlled TCI. We observed BIS for 20 min. We hypothesized that BIS remains constant, if Ce(PROP) remains constant over time.
All patients in Group M woke up, one in Group S1 and none in Group S2. In Groups S1 and S2, BIS remained constant after 11 min of constant Ce(PROP), at a more pronounced level of hypnotic drug effect than intended.
Targeting Ce(PROP) at which patients lose consciousness with effect-site-controlled TCI does not translate into an immediate constant effect.
在计算丙泊酚效应部位浓度（Ce(PROP)）的理想药代动力学-药效动力学（PK-PD）模型中，对于任何 Ce(PROP)，相应的催眠效果应该是恒定的。我们比较了三种 PK-PD 模型（Marsh PK 与 Shüttler PD、Schnider PK 与固定 ke0 以及 Schnider PK 与 Minto PD）在维持恒定双频谱指数（BIS）方面的能力，同时使用各自的效应部位控制的靶控输注（TCI）算法。
我们将 60 名患者随机分为 M 组（Marsh 模型，k(e0)=0.26 min(-1)）、S1 组或 S2 组（Schnider 模型，固定 k(e0)=0.456 min(-1)或 k(e0)适应于固定的达峰时间=1.6 min）。所有患者均以恒定速度输注丙泊酚直至意识丧失。由各模型计算得出的相应 Ce(PROP)被设定为效应部位控制 TCI 的靶目标。我们观察了 20 分钟的 BIS。我们假设如果 Ce(PROP)随时间保持不变，则 BIS 保持不变。
M 组的所有患者均苏醒，S1 组的 1 例患者和 S2 组的无患者苏醒。在 S1 组和 S2 组中，在持续的 Ce(PROP)恒定 11 分钟后，BIS 保持恒定，催眠药物效应的程度比预期的更为明显。
使用效应部位控制 TCI 将患者意识丧失时的 Ce(PROP)设定为靶目标并不能立即产生恒定的效果。
