Drug detection in breath: effects of pulmonary blood flow and cardiac output on propofol exhalation.

Breath analysis could offer a non-invasive means of intravenous drug monitoring if robust correlations between drug concentrations in breath and blood can be established. In this study, propofol blood and breath concentrations were determined in an animal model under varying physiological conditions. Propofol concentrations in breath were determined by means of two independently calibrated analytical methods: continuous, real-time proton transfer reaction mass spectrometry (PTR-MS) and discontinuous solid-phase micro-extraction coupled with gas chromatography mass spectrometry (SPME-GC-MS). Blood concentrations were determined by means of SPME-GC-MS. Effects of changes in pulmonary blood flow resulting in a decreased cardiac output (CO) and effects of dobutamine administration resulting in an increased CO on propofol breath concentrations and on the correlation between propofol blood and breath concentrations were investigated in seven acutely instrumented pigs. Discontinuous propofol determination in breath by means of alveolar sampling and SPME-GC-MS showed good agreement (R(2)=0.959) with continuous alveolar real-time measurement by means of PTR-MS. In all investigated animals, increasing cardiac output led to a deterioration of the relationship between breath and blood propofol concentrations (R(2)=0.783 for gas chromatography-mass spectrometry and R(2)=0.795 for PTR-MS). Decreasing pulmonary blood flow and cardiac output through banding of the pulmonary artery did not significantly affect the relationship between propofol breath and blood concentrations (R(2)>0.90). Estimation of propofol blood concentrations from exhaled alveolar concentrations seems possible by means of different analytical methods even when cardiac output is decreased. Increases in cardiac output preclude prediction of blood propofol concentration from exhaled concentrations.

Breath gas aldehydes as biomarkers of lung cancer.

There is experimental evidence that volatile substances in human breath can reflect presence of neoplasma. Volatile aldehydes were determined in exhaled breath of 12 lung cancer patients, 12 smokers and 12 healthy volunteers. Alveolar breath samples were collected under control of expired CO(2). Reactive aldehydes were transformed into stable oximes by means of on-fiber-derivatization (SPME-OFD). Aldehyde concentrations in the ppt and ppb level were determined by means of gas chromatography-mass spectrometry (GC-MS). Exhaled concentrations were corrected for inspired values. Exhaled C(1)-C(10) aldehydes could be detected in all healthy volunteers, smokers and lung cancer patients. Concentrations ranged from 7 pmol/l (161 pptV) for butanal to 71 nmol/l (1,582 ppbV) for formaldehyde. Highest inspired concentrations were found for formaldehyde and acetaldehyde (0-55 nmol/l and 0-13 nmol/l, respectively). Acetaldehyde, propanal, butanal, heptanal and decanal concentrations showed no significant differences for cancer patients, smokers and healthy volunteers. Exhaled pentanal, hexanal, octanal and nonanal concentrations were significantly higher in lung cancer patients than in smokers and healthy controls (p(pentanal) = 0.001; p(hexanal) = 0.006; p(octanal) = 0.014; p(nonanal) = 0.025). Sensitivity and specificity of this method were comparable to the diagnostic certitude of conventional serum markers and CT imaging. Lung cancer patients could be identified by means of exhaled pentanal, hexanal, octanal and nonanal concentrations. Exhaled aldehydes reflect aspects of oxidative stress and tumor-specific tissue composition and metabolism. Noninvasive recognition of lung malignancies may be realized if analytical skills, biochemical knowledge and medical expertise are combined into a joint effort.