Measurement of combined oximetry and cutaneous capnography during flexible bronchoscopy: Fig. 1—

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 inPc,CO2during bronchoscopy. CombinedSp,O2andPc,CO2were 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 withSp,O2recordings, thus,Sp,O2was analysed in 99 patients. Spirometry data were available in 77 patients. Multivariate analysis of covariance and logistic regression were used for statistical analyses. Mean baselinePc,CO2was 4.78±1.06 kPa (36±8 mmHg) and mean rise in thePc,CO2during bronchoscopy was 1.26±0.70 kPa (9.5±5.3 mmHg), while meanPc,CO2at the end of bronchoscopy was 5.85±1.19 kPa (44±9 mmHg) . BaselinePc,CO2and the lowestSp,O2were significantly associated with peakPc,CO2and the change inPc,CO2during bronchoscopy. Risk of significant hypoxaemia (Sp,O2≤90%) was lower for a higher baselineSp,O2. PeakPc,CO2was directly associated with significant hypoxaemia. There was no significant association in the baselinePc,CO2, peakPc,CO2, baselineSp,O2or the lowestSp,O2comparing 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.