Objective

To evaluate agreement with PaCO₂ of two low sampling rate sidestream capnometers and a mainstream capnometer in rabbits and the effect of using high fresh gas flow from a Bain coaxial breathing system.

Study design

Prospective, crossover study.

Animals

A total of 10 New Zealand White rabbits weighing 3.4 ± 0.3 kg [mean ± standard deviation (SD)].

Methods

Two sidestream analyzers (Viamed VM-2500-S and Capnostream 35) with a sampling rate of 50 mL minute^–1 and a mainstream capnometer (Capnostat 5) were tested. All capnometers used infrared spectroscopy and advanced microprocessor technology. Rabbits were anesthetized and intubated with noncuffed endotracheal tubes of 3 mm internal diameter and adequate seal. A sidestream sampling adapter or the mainstream capnometer was attached to the endotracheal tube and connected to a Bain coaxial breathing system. Oxygen (1.5 L minute^–1) delivered sevoflurane to maintain anesthesia. An auricular artery catheter allowed blood sampling for PaCO₂ analysis corrected to rectal temperature. Inspired and end-tidal carbon dioxide (Pe′CO₂) measurements were recorded during blood sample withdrawal. From each rabbit, 10 paired PaCO₂/Pe′CO₂ measurements were obtained. Each rabbit was recovered from anesthesia and was anesthetized again with an alternate capnometer after 1 week. Data were analyzed using Bland–Altman and two-way anova for repeated measures.

Results

Analysis included 100 paired samples. Negative bias reflects underestimation of PaCO₂. Bland–Altman mean (±1.95 SD) was –16.7 (–35.2 to 1.8) mmHg for Capnostat 5, –27.9 (–48.6 to –7.2) mmHg for Viamed, and –18.1 (–34.3 to –1.9) mmHg for Capnostream. Viamed PaCO₂–Pe′CO₂ gradient was greater than other two capnometers.

Conclusions

All three capnometers underestimated PaCO₂. Capnostat 5 and Capnostream performed similarly.

Clinical relevance

These capnometers underestimated PaCO₂ in spontaneously breathing rabbits anesthetized using a Bain coaxial breathing system with high fresh gas flows.

中文翻译：

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在使用贝恩同轴呼吸系统麻醉的自发呼吸兔子中，主流（Capnostat 5）和两个低流量侧流二氧化碳监测仪（VM-2500-S和Capnostream）的比较。

目的

为了评估与PaCO ₂在兔子中使用两个低采样率侧流式二氧化碳分析仪和主流式二氧化碳分析仪的一致性，以及使用来自贝恩同轴呼吸系统的高新鲜气体流量的效果。

学习规划

前瞻性，交叉研究。

动物

总共10只新西兰白兔，体重3.4±0.3kg [平均±标准偏差（SD）]。

方法

测试了两个采样率为50 mL min ^–1的侧流分析仪（Viamed VM-2500-S和Capnostream 35）和一个主流的二氧化碳分析仪（Capnostat 5）。所有的示差计均使用红外光谱和先进的微处理器技术。麻醉兔子，并用内径为3 mm且密封良好的无袖带气管插管。侧流采样适配器或主流型二氧化碳监测仪已连接到气管导管，并连接到贝恩同轴呼吸系统。氧气（1.5 L分钟^–1）输送七氟醚以维持麻醉。耳动脉导管允许采血以校正Paca _2的直肠温度。启发和呼气末二氧化碳（P E' CO ₂）在抽取血液样本期间记录测量结果。从每只兔子，10成对的二氧化碳分压₂ / P E' CO ₂中获得的测量结果。从麻醉中恢复每只兔子，并在1周后用备用二氧化碳计再次麻醉。使用Bland–Altman和双向方差分析对数据进行重复测量。

结果

分析包括100个配对样本。负偏差反映了对PaCO _2的低估。Capnostat 5的Bland–Altman平均（±1.95 SD）为–16.7（–35.2至1.8）mmHg，Vimmed为–27.9（–48.6至–7.2）mmHg，Capnostream为–18.1（–34.3至–1.9）mmHg。二氧化碳分压Viamed ₂ -P E' CO ₂梯度比其它两种capnometers更大。

结论

所有三个示高仪均低估了PaCO ₂。Capnostat 5和Capnostream的表现相似。

临床相关性

这些示波表低估了使用具有高新鲜气体流量的贝恩同轴呼吸系统麻醉的自发呼吸兔子的PaCO ₂。