Kojima Yuki, Sendo Ryozo, Okayama Naoko, Hamasaki Junichiro
Department of Anesthesiology, Asahi General Hospital, Asahi, JPN.
Department of Anesthesiology, Imakiire General Hospital, Kagoshima, JPN.
Cureus. 2022 May 18;14(5):e25122. doi: 10.7759/cureus.25122. eCollection 2022 May.
The fraction of inspired oxygen while administering oxygen to patients must be measured as it represents the alveolar oxygen concentration, which is important from a respiratory physiology viewpoint. Therefore, the purpose of this study was to compare the fractions of inspired oxygen obtained through different oxygen delivery devices.
A simulation model of spontaneous respiration was used. The fractions of inspired oxygen obtained through low- and high-flow nasal cannulas and a simple oxygen mask were measured. The fraction of inspired air was measured every second for 30 s after 120 s of oxygen administration. This was measured three times under each condition.
With a low-flow nasal cannula, airflow reduced both the intratracheal fraction of inspired oxygen and extraoral oxygen concentration, indicating that exhalatory respiration occurred during rebreathing and may be involved in increasing the intratracheal fraction of inspired oxygen.
Oxygen administration during expiratory flow may lead to an increased oxygen concentration in the anatomical dead space, which may be involved in the increase in the fraction of inspired oxygen. With a high-flow nasal cannula, a high fraction of inspired oxygen can be achieved even at a flow rate of 10 L/min. When determining the optimum amount of oxygen, it is necessary to set an appropriate flow rate for patients and specific conditions without being bound by the fraction of inspired oxygen values alone. It might be difficult to estimate the fraction of inspired oxygen while using a low-flow nasal cannula and simple oxygen mask in clinical situations.
给患者输氧时，必须测量吸入氧分数，因为它代表肺泡氧浓度，从呼吸生理学角度来看这很重要。因此，本研究的目的是比较通过不同输氧装置获得的吸入氧分数。
使用自主呼吸模拟模型。测量通过低流量和高流量鼻导管以及简易氧气面罩获得的吸入氧分数。在输氧120秒后，每隔一秒测量一次吸入空气分数，持续30秒。每种情况均测量三次。
使用低流量鼻导管时，气流降低了气管内吸入氧分数和口腔外氧浓度，表明再呼吸过程中发生了呼气呼吸，且可能参与增加气管内吸入氧分数。
呼气气流期间输氧可能会导致解剖无效腔内的氧浓度增加，这可能与吸入氧分数的增加有关。使用高流量鼻导管时，即使流速为10升/分钟也可实现高吸入氧分数。在确定最佳氧量时，有必要根据患者和具体情况设定合适的流速，而不仅仅受吸入氧分数值的限制。在临床情况下，使用低流量鼻导管和简易氧气面罩时可能难以估计吸入氧分数。
