Underner M, Peiffer G
Unité de tabacologie, service de pneumologie, pavillon René-Beauchant, CHU de Poitiers, BP 577, 86021 Poitiers cedex, France.
Rev Mal Respir. 2010 Apr;27(4):293-300. doi: 10.1016/j.rmr.2009.09.004. Epub 2010 Jan 25.
Exhaled carbon monoxide (ECO) concentration provides an easy, fast and non invasive means of assessing smoking status. However, some difficulties have to be considered when interpreting ECO levels.
CO is a non-specific biomarker of tobacco exposure. Its half-life is short (2-6 hours). CO reflects the intensity of tobacco smoke inhalation. Its high affinity for haemoglobin, producing carboxyhaemoglobin (COHb), leads to tissue hypoxia. The correlation between ECO and COHb is strong and linear. Gender, pulmonary ventilation, physical exercise and time of day may induce variations in CO elimination. ECO levels are increased in the following situations: consumption of alcohol or polyol-rich sweets, lactose intolerance, haemolytic anaemia, types 1 and 2 diabetes, asthma, chronic obstructive pulmonary disease (COPD) and bronchiectasis. Airflow obstruction alters the correlation between ECO and blood COHb. Smokers and nonsmokers can be differentiated by threshold levels of ECO in the range three to ten parts per million (ppm). For patients suffering from asthma and COPD, however, the threshold levels of ECO are 10 and 11 ppm respectively.
Both false positive results and clinical disorders associated with higher production of endogenous CO have to be taken into account when blood COHb and/or ECO levels are interpreted in clinical practice.
呼出一氧化碳（ECO）浓度提供了一种评估吸烟状况的简便、快速且无创的方法。然而，在解读ECO水平时必须考虑一些困难。
CO是烟草暴露的非特异性生物标志物。其半衰期较短（2 - 6小时）。CO反映了吸入烟草烟雾的强度。它与血红蛋白的高亲和力会产生碳氧血红蛋白（COHb），导致组织缺氧。ECO与COHb之间存在强线性相关性。性别、肺通气、体育锻炼和一天中的时间可能会引起CO清除的变化。在以下情况下ECO水平会升高：饮酒或食用富含多元醇的甜食、乳糖不耐受、溶血性贫血、1型和2型糖尿病、哮喘、慢性阻塞性肺疾病（COPD）和支气管扩张。气流阻塞会改变ECO与血液中COHb之间的相关性。吸烟者和非吸烟者可通过ECO阈值水平在百万分之三至十（ppm）范围内进行区分。然而，对于患有哮喘和COPD的患者，ECO的阈值水平分别为10 ppm和11 ppm。
在临床实践中解读血液中COHb和/或ECO水平时，必须考虑假阳性结果以及与内源性CO产生增加相关的临床疾病。
