A simple breath sampling method in intubated and mechanically ventilated critically ill patients

- A breath sampling method for volatile organic compound (VOC) analysis was developed.
- 64 VOCs emendated from the ventilator and tubing of ventilated ICU-patients.
- 44 of these “ventilator-associated VOCs” were also observed in vivo.
- VOC abundance had an inverse correlation with minute volume in vitro but not in vivo.
- Breath collection with disposable materials showed to be repeatable.

Volatile organic compounds (VOCs) in breath may serve as biomarkers of pulmonary infection or inflammation. We developed and validated a new breath sampling method for VOC analysis in ventilated patients.Breath was collected from the ventilatory circuit using cheap disposables. VOCs were identified by gas-chromatography and mass-spectrometry (GC-MS) at various minute volumes during ventilation of an artificial lung (in vitro) and ventilated patients (in vivo).Sixty-four VOCs emendated from the ventilator and tubing. Their concentrations had an inverse correlation with minute volume in in vitro experiments (median correlation coefficient: −0.61 [25-75th percentile: −0.66 to −0.43]). Forty-four of these “ventilator-associated VOCs” were also observed in vivo, without correlations with minute volume. In vivo experiments showed that only positive end-expiratory pressure influenced the concentration of breath VOCs. The sampling method was highly reproducible (median intra-class correlation 0.95 [25-75th percentile: 0.87-0.97]).In conclusion, a novel, simple and repeatable sampling method was developed and validated for capturing exhaled VOCs in ventilated patients, which could allow for large-scale breath analysis in clinical studies.