University of Otago: Christchurch, Christchurch, New Zealand.
Canterbury District Health Board, Christchurch, New Zealand.
Anaesthesia. 2019 Jul;74(7):875-882. doi: 10.1111/anae.14669. Epub 2019 Apr 29.
Reducing fresh gas flow during inhalational anaesthesia results in cost savings and decreases environmental impact. We are interested in the influence of fresh gas flow on the early (induction) phase of overall fresh gas flow and vapour consumption. This stage is often excluded in studies of fresh gas flow. Data were collected from 3199 sevoflurane anaesthetics over an 11-month period in four operating theatres. We determined fresh gas flow at different stages of anaesthesia, and developed an explanatory model for the influence of the 'induction' period. Following a three-month collection of baseline data we emphasised the importance of the early phase to our department repeatedly over a two-week period. We explored the relationship between fresh gas flow and total vapour usage, and used a simple mathematical model to explore the effect of changes in the fresh gas flow and duration of the 'induction' phase. Mean fresh gas flow was 1.15 l.min in the baseline period and 0.91 l.min in the two months following our educational effort (p = 0.0005). In the following six months, mean fresh gas flow was 1.17 l.min (p = 0.7726 compared with baseline). These results were driven by changes in both fresh gas flow and duration of the initial high-flow period. We found some correlation (R = 0.85) between overall fresh gas flow and vapour consumption; a 1 l.min increase in fresh gas flow consumes an additional 18 ml.hr of liquid sevoflurane. This preliminary study demonstrates that an episode of high fresh gas flow at the start of anaesthesia has a large and modifiable effect on overall fresh gas flow and vapour consumption. We also confirmed the linear relationship between fresh gas flow and vapour usage.
在吸入性麻醉期间减少新鲜气体流量可节省成本并减少对环境的影响。我们对新鲜气体流量对总新鲜气体流量和蒸气消耗的早期（诱导）阶段的影响感兴趣。此阶段通常在新鲜气体流量研究中被排除。在四个手术室的 11 个月期间，从 3199 例七氟醚麻醉中收集了数据。我们确定了麻醉的不同阶段的新鲜气体流量，并为“诱导”期的影响开发了一个解释模型。在收集了三个月的基线数据后，我们在两周的时间内反复向我们的部门强调早期阶段的重要性。我们探讨了新鲜气体流量与总蒸气使用量之间的关系，并使用简单的数学模型探讨了新鲜气体流量和“诱导”阶段持续时间变化的影响。在基线期间，新鲜气体流量的平均值为 1.15 l.min，在我们教育工作之后的两个月中为 0.91 l.min（p = 0.0005）。在接下来的六个月中，新鲜气体流量的平均值为 1.17 l.min（与基线相比，p = 0.7726）。这些结果是由初始高流量期的新鲜气体流量和持续时间的变化驱动的。我们发现总新鲜气体流量和蒸气消耗之间存在一定的相关性（R = 0.85）；新鲜气体流量增加 1 l.min 会消耗额外的 18 ml.hr 液体七氟醚。这项初步研究表明，麻醉开始时的高新鲜气体流量事件对总新鲜气体流量和蒸气消耗有很大且可调节的影响。我们还证实了新鲜气体流量和蒸气使用量之间的线性关系。
