经气管和口腔气体分析测量的有效吸入氧浓度。

Effective inspired oxygen concentration measured via transtracheal and oral gas analysis.

机构信息

Exercise Physiology Research Laboratory, David Geffen School of Medicine, University of California, Los Angeles, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, CA 90095-1690, USA.

出版信息

Respir Care. 2010 Apr;55(4):453-9.

PMID:20406513

Abstract

BACKGROUND

The fraction of inspired oxygen (F(IO(2))) is quoted for different oxygen delivery systems, but variations in inspiratory flow and tidal volume make precise measurement difficult. We developed a reliable method of measuring the effective F(IO(2)) in patients receiving supplemental oxygen.

METHODS

Ten subjects with chronic hypoxemia breathed through a mouthpiece with a sampling probe connected to a mass spectrometer. Four of the 10 subjects had transtracheal catheters that allowed direct sampling of tracheal gas. We used oxygen concentrations of 47% and 97%, and flow rates between 1 L/min and 8 L/min. We also compared oxygen delivery via nasal cannula and transtracheal catheter. Effective F(IO(2)) was derived from plots of the fractional concentrations of carbon dioxide versus oxygen.

RESULTS

We found excellent correlation between the effective F(IO(2)) values from tracheal and oral sampling (r = 0.960, P < .001). With 97% oxygen via nasal cannula, effective F(IO(2)) increased by 2.5% per liter of increased flow (P < .001); effective F(IO(2)) reached 32.7% at 5 L/min while P(aO(2)) increased by 12 mm Hg per liter of increased flow. In 4 subjects with a transtracheal catheter, effective F(IO(2)) increased 5.0% (P < .001) per liter of increased flow, and P(aO(2)) increased by 13 mm Hg per liter of increased flow, whereas in the same 4 subjects using nasal cannula for oxygen delivery, P(aO(2)) increased by only 6 mm Hg per liter of increased flow.

CONCLUSIONS

Exhaled gas sampled at the mouth accurately reflected the effective F(IO(2)) in the trachea. In relation to inspired oxygen flow, the effective F(IO(2)) was lower than is conventionally thought. Compared to nasal cannula, transtracheal catheter approximately doubled the effective F(IO(2)) at a given flow rate. Accurate knowledge of F(IO(2)) should aid clinicians in managing patients with acute and chronic lung diseases.

摘要

背景

吸入氧气分数（F(IO(2))) 被引用用于不同的供氧系统，但吸气流量和潮气量的变化使得精确测量变得困难。我们开发了一种可靠的方法来测量接受补充氧气的患者的有效 F(IO(2))。

方法

10 名患有慢性低氧血症的受试者通过带有采样探头的口器呼吸，该探头连接到质谱仪。其中 4 名受试者有经气管导管，允许直接采集气管气体。我们使用 47%和 97%的氧气浓度，以及 1 至 8 升/分钟的流量。我们还比较了经鼻导管和经气管导管输送的氧气。有效 F(IO(2)) 是从二氧化碳与氧气的分数浓度图中得出的。

结果

我们发现经气管和口腔采样的有效 F(IO(2))值之间存在极好的相关性（r = 0.960，P<.001）。经鼻导管给予 97%氧气时，流量增加 1 升/分钟，有效 F(IO(2))增加 2.5%（P<.001）；当流量达到 5 升/分钟时，有效 F(IO(2))达到 32.7%，而 P(aO(2))随流量增加每增加 1 升/分钟增加 12 毫米汞柱。在 4 名有经气管导管的受试者中，流量增加 1 升/分钟时，有效 F(IO(2))增加 5.0%（P<.001），而 P(aO(2))随流量增加每增加 1 升/分钟增加 13 毫米汞柱，而在同一 4 名接受经鼻导管供氧的受试者中，P(aO(2))仅增加 6 毫米汞柱/分钟。