FEV manoeuvre induced changes in breath VOC compositions: an unconventional view on lung function tests

Abstract

Breath volatile organic compound (VOC) analysis can open a non-invasive window onto pathological and metabolic processes in the body. Decades of clinical breath-gas analysis have revealed that changes in exhaled VOC concentrations are important rather than disease specific biomarkers. As physiological parameters, such as respiratory rate or cardiac output, have profound effects on exhaled VOCs, here we investigated VOC exhalation under respiratory manoeuvres. Breath VOCs were monitored by means of real-time mass-spectrometry during conventional FEV manoeuvres in 50 healthy humans. Simultaneously, we measured respiratory and hemodynamic parameters noninvasively. Tidal volume and minute ventilation increased by 292 and 171% during the manoeuvre. FEV manoeuvre induced substance specific changes in VOC concentrations. pET-CO2 and alveolar isoprene increased by 6 and 21% during maximum exhalation. Then they decreased by 18 and 37% at forced expiration mirroring cardiac output. Acetone concentrations rose by 4.5% despite increasing minute ventilation. Blood-borne furan and dimethyl-sulphide mimicked isoprene profile. Exogenous acetonitrile, sulphides, and most aliphatic and aromatic VOCs changed minimally. Reliable breath tests must avoid forced breathing. As isoprene exhalations mirrored FEV performances, endogenous VOCs might assure quality of lung function tests. Analysis of exhaled VOC concentrations can provide additional information on physiology of respiration and gas exchange.

Molecular breath analysis supports altered amino acid metabolism in idiopathic pulmonary fibrosis

“…All subjects refrained from eating, smoking, using chewing gum, tooth brushing and drinking anything except water within 1 h prior to the measurement. The sampling procedure was standardized across all subjects, to exclude confounding influences from varying exhalation manoeuvres . Positive ion mode was used, with a mass range of 40–450 Da.…”

Exhaled breath analysis: a review of ‘breath-taking’ methods for off-line analysis

“…Time-controlled breath samples have been shown to be unreliable (Miekisch et al 2008) and also with various timings used in different studies, there is no known optimal exclusion time duration. Concerns regarding reproducibility also arise due to distinct physiological properties of individuals such as cardiac output and pulmonary ventilation which may also introduce unwanted variability even within individuals sampled repeatedly in different physiological states (Cope et al 2004; Sukul et al 2016). Other sources of variability which may contribute to a lack of reproducibility include breath holding and expiratory flow rate which may alter VOC concentrations (Dweik et al 2011; Sukul et al 2014).…”

Standardization procedures for real-time breath analysis by secondary electrospray ionization high-resolution mass spectrometry

“…Some studies indicate that the exhalation maneuver itself can in some cases alter the metabolic profile, hence providing misleading results [32]. For this reason, we further investigated whether the exhalation flow rate of our protocol had an impact on the breath-signal of the exhaled metabolites.…”

“…However, most of the published SESI-MS studies rely on lab-built instrumentation, making it difficult to standardize procedures for this technique. Following ongoing efforts to standardize exhaled breath collection and subsequent analysis for other analytical platforms [27][28][29][30][31][32][33][34], we present here a series of instrumental developments aiming to standardize breath analysis procedures and to provide recommendations for SESI-HRMS users interested in breath analysis. To do so, we characterized a series of new instrumentation with a focus on a panel of three classes of exhaled aldehydes.…”