Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA.
Clin Chem. 2019 Sep;65(9):1171-1179. doi: 10.1373/clinchem.2019.304501. Epub 2019 Jul 11.
Cannabis use results in impaired driving and an increased risk of motor vehicle crashes. Cannabinoid concentrations in blood and other matrices can remain high long after use, prohibiting the differentiation between acute and chronic exposure. Exhaled breath has been proposed as an alternative matrix in which concentrations may more closely correspond to the window of impairment; however, efficient capture and analytically sensitive detection methods are required for measurement.
Timed blood and breath samples were collected from 20 volunteers before and after controlled administration of smoked cannabis. Cannabinoid concentrations were measured using LC-MS/MS to determine release kinetics and correlation between the 2 matrices.
Δ9-Tetrahydrocannabinol (THC) was detected in exhaled breath for all individuals at baseline through 3 h after cannabis use. THC concentrations in breath were highest at the 15-min timepoint (median = 17.8 pg/L) and declined to <5% of this concentration in all participants 3 h after smoking. The decay curve kinetics observed for blood and breath were highly correlated within individuals and across the population.
THC can be reliably detected throughout the presumed 3-h impairment window following controlled administration of smoked cannabis. The findings support breath THC concentrations as representing a physiological process and are correlated to blood concentrations, albeit with a shorter window of detection.
大麻的使用会导致驾驶能力受损，增加机动车事故的风险。血液和其他基质中的大麻素浓度在使用后很长时间内仍保持较高水平，这使得难以区分急性和慢性暴露。呼气已被提议作为一种替代基质，其中浓度可能更接近损伤窗口；然而，需要有效的捕获和分析敏感的检测方法进行测量。
在 20 名志愿者接受受控吸烟大麻后，定时采集血液和呼吸样本。使用 LC-MS/MS 测量大麻素浓度，以确定释放动力学和两种基质之间的相关性。
在基线时，所有个体的呼气中均检测到Δ9-四氢大麻酚（THC），直至吸烟后 3 小时。呼气中 THC 浓度在 15 分钟时最高（中位数=17.8 pg/L），所有参与者在吸烟后 3 小时内降至该浓度的<5%。个体内和人群中观察到的血液和呼吸的衰减曲线动力学高度相关。
在受控吸烟大麻后，可在假定的 3 小时损伤窗口内可靠地检测到 THC。研究结果支持呼气 THC 浓度代表生理过程，并与血液浓度相关，尽管检测窗口较短。
