笑气对小儿最低流量与低流量麻醉期间七氟醚蒸发器设置的影响。

Effect of N2O on sevoflurane vaporizer settings during minimal- and low-flow anesthesia.

作者信息

Hendrickx Jan F A, Coddens José, Callebaut Frederik, Artico Hermes, Deloof Thierry, Demeyer Ignace, De Wolf Andre M

机构信息

Department of Anesthesiology, Intensive Care and Pain Therapy, Onze Lieve Vrouw Hospital, Aalst, Belgium.

出版信息

Anesthesiology. 2002 Aug;97(2):400-4. doi: 10.1097/00000542-200208000-00017.

DOI:10.1097/00000542-200208000-00017

PMID:12151930

Abstract

BACKGROUND

Uptake of a second gas of a delivered gas mixture decreases the amount of carrier gas and potent inhaled anesthetic leaving the circle system through the pop-off valve. The authors hypothesized that the vaporizer settings required to maintain constant end-expired sevoflurane concentration (Etsevo) during minimal-flow anesthesia (MFA, fresh gas flow of 0.5 l/min) or low-flow anesthesia (LFA, fresh gas flow of 1 l/min) would be lower when sevoflurane is used in oxygen-nitrous oxide than in oxygen.

METHODS

Fifty-six patients receiving general anesthesia were randomly assigned to one of four groups (n = 14 each), depending on the carrier gas and fresh gas flow used: group Ox.5 l (oxygen, MFA), group NOx.5 l (oxygen-nitrous oxide, MFA after 10 min high fresh gas flow), group Ox1 l (oxygen, LFA), and group NOx1 l (oxygen-nitrous oxide, LFA after 10 min high fresh gas flow). The vaporizer dial settings required to maintain Etsevo at 1.3% were compared between groups.

RESULTS

Vaporizer settings were higher in group Ox.5 l than in groups NOx.5 l, Ox1 l, and NOx1 l; vaporizer settings were higher in group NOx.5 l than in group NOx1 l between 23 and 47 min, and vaporizer settings did not differ between groups Ox1 l and NOx1 l.

CONCLUSIONS

When using oxygen-nitrous oxide as the carrier gas, less gas and vapor are wasted through the pop-off valve than when 100% oxygen is used. During MFA with an oxygen-nitrous oxide mixture, when almost all of the delivered oxygen and nitrous oxide is taken up by the patient, the vaporizer dial setting required to maintain a constant Etsevo is lower than when 100% oxygen is used. With higher fresh gas flows (LFA), this effect of nitrous oxide becomes insignificant, presumably because the proportion of excess gas leaving the pop-off valve relative to the amount taken up by the patient increases. However, other unexplored factors affecting gas kinetics in a circle system may contribute to our observations.

摘要

背景

所输送气体混合物中第二种气体的摄取会减少通过逸气阀离开环路系统的载气和强效吸入麻醉剂的量。作者推测，在低流量麻醉（MFA，新鲜气体流量为0.5升/分钟）或低流量麻醉（LFA，新鲜气体流量为1升/分钟）期间，为维持呼气末七氟醚浓度（Etsevo）恒定所需的蒸发器设置，当七氟醚用于氧化亚氮 - 氧气混合气时要低于用于纯氧时。

方法

56例接受全身麻醉的患者根据所用载气和新鲜气体流量随机分为四组（每组n = 14）：Ox.5 l组（氧气，MFA）、NOx.5 l组（氧化亚氮 - 氧气混合气，10分钟高新鲜气体流量后MFA）、Ox1 l组（氧气，LFA）和NOx1 l组（氧化亚氮 - 氧气混合气，10分钟高新鲜气体流量后LFA）。比较各组将Etsevo维持在1.3%所需的蒸发器刻度盘设置。

结果

Ox.5 l组的蒸发器设置高于NOx.5 l组、Ox1 l组和NOx1 l组；在23至47分钟之间，NOx.5 l组的蒸发器设置高于NOx1 l组，Ox1 l组和NOx1 l组之间的蒸发器设置无差异。

结论

当使用氧化亚氮 - 氧气混合气作为载气时，通过逸气阀浪费的气体和蒸汽比使用100%氧气时少。在使用氧化亚氮 - 氧气混合气的MFA期间，当几乎所有输送的氧气和氧化亚氮都被患者摄取时，维持Etsevo恒定所需的蒸发器刻度盘设置低于使用100%氧气时。对于更高的新鲜气体流量（LFA），氧化亚氮的这种作用变得不明显，可能是因为通过逸气阀离开的过量气体相对于患者摄取量的比例增加。然而，其他未探究的影响环路系统中气体动力学的因素可能也与我们的观察结果有关。