Quantification of Volatile Aldehydes Deriving from In Vitro Lipid Peroxidation in the Breath of Ventilated Patients

Abstract

Exhaled aliphatic aldehydes were proposed as non-invasive biomarkers to detect increased lipid peroxidation in various diseases. As a prelude to clinical application of the multicapillary column–ion mobility spectrometry for the evaluation of aldehyde exhalation, we, therefore: (1) identified the most abundant volatile aliphatic aldehydes originating from in vitro oxidation of various polyunsaturated fatty acids; (2) evaluated emittance of aldehydes from plastic parts of the breathing circuit; (3) conducted a pilot study for in vivo quantification of exhaled aldehydes in mechanically ventilated patients. Pentanal, hexanal, heptanal, and nonanal were quantifiable in the headspace of oxidizing polyunsaturated fatty acids, with pentanal and hexanal predominating. Plastic parts of the breathing circuit emitted hexanal, octanal, nonanal, and decanal, whereby nonanal and decanal were ubiquitous and pentanal or heptanal not being detected. Only pentanal was quantifiable in breath of mechanically ventilated surgical patients with a mean exhaled concentration of 13 ± 5 ppb. An explorative analysis suggested that pentanal exhalation is associated with mechanical power—a measure for the invasiveness of mechanical ventilation. In conclusion, exhaled pentanal is a promising non-invasive biomarker for lipid peroxidation inducing pathologies, and should be evaluated in future clinical studies, particularly for detection of lung injury.

Influence of ventilatory parameters on the concentration of exhaled volatile organic compounds in mechanically ventilated patients

“…For propanal and pentanal a statistically significant increase in maximum has been observed at the highest respiratory rate values. This is in agreement with recent studies carried out on ventilated patients 51 and animal models, 52 showing a positive correlation between breath pentanal and mechanical ventilation pressure, probably because of an increase in lipid peroxidation and oxidation stress. Phenols ( phenol, methyl-phenol and ethyl-phenol) and C2-C6 carboxylic acids have also been linked to oesophago-gastric cancer.…”

Ion Mobility Spectrometry Towards Environmental Volatile Organic Compounds Identification and Quantification: a Comparative Overview over Infrared Spectroscopy

“…As mentioned, acetone is a common air compound; however, nonanal and octanal seem to be human-characteristic. Benzaldehyde, heptanal, acetic acid, 2-pentanone, and decanal were identified in at least two independent studies on human emanated analytes, [24,75,105,108,109], proving that they should be targeted with a more profound study and, again, showing the IMS results consistency. Not being able to exhaustively analyze all the addressed works, Table S2 in the Supplementary Materials, summarizes all the identified VOCs by ion mobility spectrometry, enabling a direct comparison among independent works.…”

“…Similarly, ethanol is also a very common analyte, being identified in [10,[79][80][81]106]. Among all the addressed works underlying this review, hexanal is the most common analyte to be identified [10,24,75,79,105,106,108,109]. On the other hand, some volatile compounds were only identified in a small number of papers.…”

“…Generally speaking, it is possible to see identical results in independent studies with a similar goal, which gives consistency to the IMS technique. For instance, being the detection of human metabolites as the main goal, some VOCs were found to be characteristic of human presence, namely, nonanal, octanal, and acetone, all detected in four of the addressed studies [24,75,108,109]. As mentioned, acetone is a common air compound; however, nonanal and octanal seem to be human-characteristic.…”

Exhaled VOC Biomarkers from Rats Injected with PMs from Thirty-One Major Cities in China

“…Molecular Mechanism behind Exhaled VOC Profiles of Rats. Through literature research and the KEGG pathway analysis, 23,28,29,43,44 we identified the molecular mechanisms behind 13 biomarkers of exhaled VOCs (Figure 5). We found that the citrate cycle (TCA cycle), the fundamental metabolic pathway for the breakdown of carbohydrates, fats, and proteins in cell mitochondria, 45,46 is closely related to the production of ketones (hydroxyacetone and acetone), acids (acetic acid and lactate), and alcohols (1-propanol and butan-1-ol) in exhaled VOCs.…”