Textbooks of anaesthesia describe in detail the calculations associated with splitting ratios created in variable bypass vapourisers. These calculations are based on assumptions of carrier gas flow (eg:assume 150 ml) as practised with measured flow vaporizers[1,2]. Carrier gas flow in a variable bypass vaporizer is agent specific,dynamic,unknown and operator independent.Therefore assuming carrier gas flow in calculations related to variable bypass vaporisers is without rationale[3]. In spite of technological advance,the amount of vapour produced is calculated based on clinically impractical assumptions. A simple method and formula is suggested for the quick estimate of vapour output, carrier gas flow and determine the splitting ratio while operating a sevoflurane variable bypass vaporizer.

中文翻译：

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七氟醚汽化器的分流比——计算的重新审视

麻醉教科书详细描述了与可变旁路汽化器中产生的分流比相关的计算。这些计算基于载气流量的假设（例如：假设 150 ml），与测量流量蒸发器的实践相同[1,2]。可变旁路汽化器中的载气流量是特定于试剂的、动态的、未知的且与操作员无关。因此，在与可变旁路汽化器相关的计算中假设载气流量是没有道理的[3]。尽管技术进步，产生的蒸气量是基于临床上不切实际的假设来计算的。提出了一种简单的方法和公式，用于在操作七氟醚可变旁路汽化器时快速估计蒸汽输出、载气流量并确定分流比。