Molecular breath-gas analysis by online mass spectrometry in mechanically ventilated patients: a new software-based method of CO ₂ -controlled alveolar gas monitoring

Abstract

Analysis of volatile organic compounds (VOCs) in exhaled breath offers diagnostic potential in research and clinical medicine. Mass spectrometry of expiratory air allows VOC measurements in a concentration range from parts per trillion to parts per million. For the reduction of dilution-related measurement errors due to dead space admixture, the precise identification of the end-expiratory phase of expiration is essential. We used a combination of two integrated MS systems consisting of a conventional MS capable of fast CO(2) tracing controlling a second, highly sensitive MS for the measurement of VOCs based on ion-molecule-reaction-MS (IMR-MS). This study intended to test the applicability of a software-based method of CO(2)-controlled alveolar breath-gas sampling in 12 ventilated patients using acetaldehyde, acetone, ethanol and isoprene as target VOCs (IMR-MS compound integration time 500 ms, cycle time 2 ms, measurement time 120 min). CO(2)-controlled versus mixed inspiratory/expiratory results are as follows: acetaldehyde 71* (61-133) versus 63 (47-87); acetone 544* (208-1174) versus 504 (152-950); ethanol 133 (99-166) versus 123 (108-185); isoprene 118* (69-253) versus 58 (44-112) (values in ppbv as medians with 25-75%; *p < 0.05 versus mixed inspiratory/expiratory values). The applied software-based CO(2)-controlled sampling method of expiratory air resulted in significant higher concentrations of acetaldehyde, acetone and isoprene.

Exhaled breath metabolomics as a noninvasive diagnostic tool for acute respiratory distress syndrome

“…An array of sensors or rapid mass-spectrometric techniques may be used for that [13]. This may also allow for continuous monitoring [54] of the development of lung injury in ventilated patients.…”

Time course of expiratory propofol after bolus injection as measured by ion molecule reaction mass spectrometry

“…These techniques range from discontinuous techniques like thermal desorption gas chromatography-mass spectrometry (analytical time hours to days) [2,9] to fast discontinuous methods like solid-phase microextraction coupled with gas chromatography mass spectrometry or ion mobility spectrometry coupled to a multicapillary column for pre-separation (analytical time within minutes) [10,11]. Very fast on-line methods like ion molecule reaction mass spectrometry, selective ion flow tube mass spectrometry, or proton transfer reaction mass spectrometry (analytical time within milliseconds to seconds) can also be used [1,4,5,8,12,13].…”

Direct Analysis Mass Spectrometry

“…Another investigation using IMR-MS examined breath gas from patients who were mechanically ventilated and compared the results from IMR-MS with a conventional electron impact mass spectrometer for monitoring CO 2 . The study reported measurements of acetaldehyde, acetone, ethanol, and isoprene in alveolar breath [45]. IMR-MS was also investigated for identifying breath gas marker candidates in liver disease [46] and in developing a more rapid test for distinguishing between gram-positive bacteria by monitoring the VOCs produced from cultures [47].…”