Department of Anesthesiology, Armand Trousseau Hospital, AP-HP, UPMC, Paris, France.
Br J Anaesth. 2012 Apr;108(4):648-54. doi: 10.1093/bja/aer459. Epub 2012 Jan 19.
In children, sevoflurane is the most commonly used anaesthetic. Its excellent haemodynamic tolerance gives it a wide therapeutic index. This halogenated agent can abolish movement [minimal alveolar concentration (MAC)] or haemodynamic responses (MACBAR) to noxious stimulus in children as in adults. Reflex pupillary dilatation (RPD) has been demonstrated as a very sensitive measure of noxious stimulation. In order to investigate the effect of sevoflurane on the RPD, a subcortical reflex, we determined the MAC of sevoflurane inhibiting the RPD in 50% of the subjects in response to skin incision (MACpup) in pre- and post-pubertal subjects.
We included 30 pre-pubertal children and 19 post-pubertal subjects. Patients received sevoflurane at preselected concentrations according to an 'up and down' design, and after a steady-state period, skin incision was performed. The RPD was considered as significant when the pupillary diameter increased by more than 100%. Heart rate (HR) and bispectral index (BIS) changes were analysed according to the pupillary response.
The MACpup of sevoflurane was 4.8% (95% confidence interval, 4.6-5.1%) in pre-pubertal children vs 3.4% (3.5-3.3%) in post-pubertal subjects (P<0.001). Inhibition of RPD was always associated with lack of significant HR response. In pre-pubertal children receiving high concentrations of sevoflurane, RPD in response to noxious stimulation was frequently associated with lack of HR response and low BIS values.
MACpup was higher than MAC and close to the MACBAR. Inhibition of RPD in pre-pubertal children required higher sevoflurane concentrations compared with post-pubertal subjects, suggesting that the relationship between the brain structure sensitivities may differ with brain maturation.
在儿童中，七氟醚是最常用的麻醉剂。其出色的血液动力学耐受性使其治疗指数较宽。这种卤代药物可以消除儿童和成人对有害刺激的运动[最小肺泡浓度（MAC）]或血液动力学反应（MACBAR）。反射性瞳孔扩张（RPD）已被证明是一种非常敏感的有害刺激测量方法。为了研究七氟醚对 RPD 的影响，我们确定了 50%的儿童对皮肤切口（MACpup）的 RPD 抑制的七氟醚 MAC，以了解皮质下反射。在青春期前和青春期后的受试者中。
我们纳入了 30 名青春期前的儿童和 19 名青春期后的受试者。根据“上下”设计，患者在预先选择的浓度下接受七氟醚，在稳定状态后进行皮肤切口。当瞳孔直径增加超过 100%时，将 RPD 视为显著。根据瞳孔反应分析心率（HR）和双谱指数（BIS）变化。
七氟醚的 MACpup 在青春期前的儿童中为 4.8%（95%置信区间，4.6-5.1%），在青春期后的受试者中为 3.4%（3.5-3.3%）（P<0.001）。RPD 抑制总是与 HR 反应缺乏显著相关。在接受高浓度七氟醚的青春期前儿童中，对有害刺激的 RPD 反应经常与 HR 反应缺乏和 BIS 值低相关。
MACpup 高于 MAC，接近 MACBAR。与青春期后的受试者相比，青春期前儿童抑制 RPD 需要更高的七氟醚浓度，这表明大脑结构敏感性之间的关系可能因大脑成熟度而异。
