以前勤務していた大阪の北野病院(参照)で関わった研究の成果をまとめた論文が掲載受理されました。
"Exhaled carbon monoxide levels change in relation to inspired oxygen fraction during
general anesthesia Takehiko Adachi, Kiichi Hirota, Tomoko Hara, Yukiko Sasaki and Yasufumi Hara Anesthesia and Analgesia, in press"
これはとても興味深い現象です。足立先生がデータを取っていて見つけました。
呼気中のCOを測定して何かの指標にしようとする場合、絶対に考慮する必要のある現象です。
機序なども考えると結構奥深いものがあると思います。
この研究は日本学術振興会の科学研究費をもらって遂行したものです。北野病院に在籍している医師は北野病院に在籍したまま科研費に応募できるという特典があります。
すごいでしょう。
Abstract
Background: Heme oxygenase produces carbon monoxide (CO) during the breakdown of heme molecules. A variety of stressors are known to upregulate this enzymatic activity and can increase exhaled CO levels. Recently, exhaled CO levels have been reported to increase in critically ill patients and after anesthesia and surgery. To use this measurement during mechanical ventilation, it is important to clarify the effects of factors which interfere with exhaled CO levels. The fraction of inspired oxygen (FiO2) is often changed during artificial ventilation. To investigate the effect of changes of FiO2 on exhaled CO, we measured exhaled CO levels during general anesthesia. Methods: Thirty patients who underwent elective operation were enrolled in this study. Anesthesia was maintained with sevoflurane and fentanyl. All patients were intubated and ventilated with a non-rebreathing ventilator. Exhaled CO levels were measured in gas sampled from the expired limb of the respiration circuit using a CO monitor. The effects of sequential changes of FiO2 on exhaled CO levels, and the effects of long-term inhalation of FiO2 0.75 and FiO2 0.35 on exhaled CO levels and arterial carboxyhemoglobin (COHb) concentrations were investigated. Results: Exhaled CO levels changed rapidly in response to changes of FiO2. Long-term inhalation of FiO2 0.75 initially increased and then gradually decreased exhaled CO to basal levels, concomitant with a decrease of arterial COHb. Long-term inhalation of FiO2 0.35 did not elicit any significant change in the observed parameters. Conclusion: When monitoring exhaled CO levels during mechanical ventilation, it is important to consider the effects of FiO2.