The aim of the present study was to assess the feasibility of measuring combined arterial oxygen saturation measured by pulse oximetry (Sp,O2) and cutaneous carbon dioxide tension (Pc,CO2) to monitor ventilation and quantify change in Pc,CO2 during bronchoscopy. Combined Sp,O2 and Pc,CO2 were measured at the ear lobe in 114 patients. In four patients, the ear-clip slipped and they were excluded. In total, 11 patients had artefacts with Sp,O2 recordings, thus, Sp,O2 was analysed in 99 patients. Spirometry data were available in 77 patients. Multivariate analysis of covariance and logistic regression were used for statistical analyses. Mean baseline Pc,CO2 was 4.78+/-1.06 kPa (36+/-8 mmHg) and mean rise in the Pc,CO2 during bronchoscopy was 1.26+/-0.70 kPa (9.5+/-5.3 mmHg), while mean Pc,CO2 at the end of bronchoscopy was 5.85+/-1.19 kPa (44+/-9 mmHg) . Baseline Pc,CO2 and the lowest Sp,O2 were significantly associated with peak Pc,CO2 and the change in Pc,CO2 during bronchoscopy. Risk of significant hypoxaemia (Sp,O2<or=90%) was lower for a higher baseline Sp,O2. Peak Pc,CO2 was directly associated with significant hypoxaemia. There was no significant association in the baseline Pc,CO2, peak Pc,CO2, baseline Sp,O2 or the lowest Sp,O2 comparing patients with and without chronic obstructive pulmonary disease. In conclusion, it is feasible to measure combined pulse oximetry and cutaneous carbon dioxide tension effectively to monitor ventilation during flexible bronchoscopy.