Exhaled Carbon Monoxide as a Noninvasive Marker of Airway Neutrophilia After Lung Transplantation

Abstract

Elevated eCO levels in stable LTx recipients may reflect an increased BAL neutrophilia and could, therefore, be used as a noninvasive marker for airway inflammation after LTx.

Smoking resumption after lung transplantation: a sobering truth

“…False-negative tests could be prevented by repeated or unexpected COT tests. Although a lot less sensitive, eCO may be adequate to confirm the questionnaire or COT findings, but probably not to discriminate current from secondhand or nonsmokers as eCO may also be increased due to elevated airway neutrophilia after LTx [4].…”

“…The gold standard for screening, however, is currently unknown. Although a questionnaire is subjective; it has a good sensitivity/specificity to detect smoking and a good correlation with the COT test [10], a more objective assessment of the patient's nicotine-exposure [4,11]. Despite being sensitive, COT conversely has a lower specificity as it may be falsely positive because of NRT or intensive second-hand smoking.…”

“…passive exposure via relatives or environmental exposure via social/work-related contacts) as well as the use of nicotine-replacement therapy (NRT). COT was assessed by gas chromatography and mass spectrometry (Thermo Scientific, Geel, Belgium) and eCO by using an electrochemical sensor (Bedfont Scientific, Kent, UK; detection limit 1 ppm), as previously described [3,4]. Statistical analyses were performed with Graphpad Prism 4.0 (San Diego, CA, USA).…”

Exhaled nitric oxide and carbon monoxide in lung transplanted patients

“…In LTX patients, eCO has been reported as a useful tool for the early detection of CLAD and it can enhance the negative predictive value of eNO for BOS [19]. Vos et al reported, analogously to FeNO, a direct correlation between eCO levels, neutrophilic count and BAL pro-inflammatory cytokine levels [20].…”

“…Two previous studies indicated a potential role of eCO as a risk predictor of BOS development, suggesting that higher eCO levels in BOS patients, especially at stage 0p and 1, ensued from an abnormal expression of heme oxygenase-1 activity in response to oxidative stress [19,20]. However, different devices were used to measure eCO and possible factors affecting eCO levels (such as current therapy and active-passive smoking exposure) were not considered.…”