We thank Tokumine et al. for the valuable insights on the potential contribution of system leaks on the loss of sevoflurane [1]. If, as their findings convincingly suggest, the system leaks should be considered negligible, the question remains as to how the missing sevoflurane escaped the system [2]. Given that substantially higher systemic absorption is unlikely, incomplete capture by CONTRAfluran™ (Baxter International, Deerfield, IL, USA) appears to be one of the few plausible explanations.

Since the interaction between activated carbon and sevoflurane is driven by non-covalent forces (primarily Van der Waals interactions which are reversible) it is plausible that, particularly under high fresh gas flow and low partial pressure of sevoflurane, there is incomplete capture or even dissociation and re-release of sevoflurane. It is noteworthy that, to enable the recycling of the adsorbed volatile anaesthetics, the substrate of CONTRAfluran must be selected such that the molecular binding is not excessively strong, allowing desorption at a sufficiently low temperature to avoid degradation of the sevoflurane molecules [3].

In our study protocol, we aimed to achieve maximum elimination of sevoflurane with the patients' trachea intubated. Immediately after stopping sevoflurane administration, we maintained a fresh gas flow of 9 l.min^-1 for a considerable duration until the patient was responsive. A certain amount of desorption and re-release may have occurred during this phase. A possible recommendation could be to use a lower fresh gas flow during the elimination phase of volatile anaesthesia to minimise desorption. This reflects that there is still considerable room for further optimisation of the technology.

我们感谢德峰等人。关于系统泄漏对七氟烷损失的潜在影响的宝贵见解[ 1 ]。如果，正如他们的研究结果令人信服地表明的那样，系统泄漏应该被认为可以忽略不计，那么问题仍然是丢失的七氟醚如何逃逸系统[ 2 ]。鉴于不太可能出现大幅较高的全身吸收，CONTRAfluran™（Baxter International，Deerfield，IL，美国）的不完全捕获似乎是少数合理的解释之一。

由于活性炭和七氟醚之间的相互作用是由非共价力驱动的（主要是可逆的范德华相互作用），因此，特别是在高新鲜气流和低七氟醚分压下，可能存在不完全捕获甚至解离并重新释放七氟醚。值得注意的是，为了能够回收所吸附的挥发性麻醉剂，必须选择 CONTRAfluran 的底物，使得分子结合不会太强，从而允许在足够低的温度下解吸，以避免七氟醚分子的降解[ 3 ]。

在我们的研究方案中，我们的目标是在患者气管插管的情况下最大限度地消除七氟醚。停止七氟醚给药后，我们立即在相当长的时间内维持 9 l.min ^-1的新鲜气流，直到患者有反应。在此阶段可能发生一定量的解吸和再释放。可能的建议是在挥发性麻醉的消除阶段使用较低的新鲜气体流量，以尽量减少解吸。这反映出该技术仍有相当大的进一步优化空间。