Sim M A B, Dean P, Kinsella J, Black R, Carter R, Hughes M
University Department of Anaesthesia, Glasgow Royal Infirmary, Glasgow, UK.
Anaesthesia. 2008 Sep;63(9):938-40. doi: 10.1111/j.1365-2044.2008.05536.x. Epub 2008 Jun 6.
Oxygen is the commonest drug prescribed in hospitals. The inhaled concentration is altered by the administered oxygen flow rate, the characteristics of the delivery device and the patient's respiratory pattern. Using healthy volunteers we measured the inspired oxygen concentration achieved with different devices both at rest and when the breathing pattern of respiratory failure was simulated by binding the subjects' chests until the forced expiratory volume in 1 s was reduced by > 50% and the respiratory rate was > 25 breaths.min(-1). With this respiratory pattern, there was a statistically significant fall in F(I)o(2) while administering oxygen via a Hudson mask at 4 l.min(-1) (23.8% (95% CI 17.4-30.3%) reduction), 12 l.min(-1), humidified (17.8% (95% CI 8.8-26.7%) reduction) and 24 l.min(-1), humidified (12.2% (95% CI 5.0-19.3%) reduction). There was no statistically significant change with a nonrebreathing (reservoir) mask at 15 and 110 l.min(-1) or with a Vapotherm 2000i at 40 l.min(-1), humidified, via nasal prongs. We conclude that the F(I)o(2) delivered by high flow devices is unaffected when the breathing pattern of respiratory failure is simulated. The F(I)o(2) achieved at rest by a nonrebreathing mask (0.68) is less than that often quoted in the literature.
氧气是医院里最常用的药物。吸入的氧浓度会因给予的氧流量、输送装置的特性以及患者的呼吸模式而改变。我们使用健康志愿者，测量了在静息状态下以及通过束缚受试者胸部模拟呼吸衰竭的呼吸模式（直到1秒用力呼气量减少>50%且呼吸频率>25次/分钟）时，不同装置所达到的吸入氧浓度。在这种呼吸模式下，通过哈德逊面罩以4升/分钟的流量给予氧气时，吸入氧分数（F(I)o(2)）有统计学意义的下降（降低23.8%（95%可信区间17.4 - 30.3%）），以12升/分钟、湿化状态给予氧气时下降17.8%（95%可信区间8.8 - 26.7%），以24升/分钟、湿化状态给予氧气时下降12.2%（95%可信区间5.0 - 19.3%）。使用非重复呼吸（储氧）面罩以15和110升/分钟的流量，或通过鼻导管以40升/分钟、湿化状态使用Vapotherm 2000i时，没有统计学意义的变化。我们得出结论，当模拟呼吸衰竭的呼吸模式时，高流量装置输送的F(I)o(2)不受影响。非重复呼吸面罩在静息状态下达到的F(I)o(2)（0.68）低于文献中经常引用的值。
