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

Respir Physiol Neurobiol. 2014 Jan 15;191:67-74. doi: 10.1016/j.resp.2013.11.001. Epub 2013 Nov 12.


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.

Keywords: Exhaled breath; Intensive care; Methodology; Volatile organic compounds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Biomarkers
  • Breath Tests / methods*
  • Critical Illness*
  • Female
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Intensive Care Units
  • Male
  • Middle Aged
  • Reproducibility of Results
  • Respiration*
  • Respiration, Artificial / instrumentation
  • Respiration, Artificial / methods*
  • Volatile Organic Compounds*


  • Biomarkers
  • Volatile Organic Compounds