Measurement of combined oximetry and cutaneous capnography during flexible bronchoscopy

¹ Pulmonary Medicine, University Hospital Basel, Switzerland

^* To whom correspondence should be addressed. E-mail: PChhajed{at}uhbs.ch.

	Abstract

To assess the feasibility of measuring combined oximetry (SpO₂) and cutaneous carbon dioxide tension (PcCO₂) to monitor ventilation and quantify change in PcCO₂ during bronchoscopy.

Combined SpO₂ and PcCO₂ were measured at the ear lobe in 114 patients. In four patients the ear clip slipped and hence excluded. 11 patients had artefacts with SpO₂ recordings and hence SpO₂ was analyzed in 99 patients. Spirometry data were available in 77 patients. Multivariate analysis of covariance and logistic regression were used for statistical analyses.

Mean baseline PcCO₂ was 36±8 mm Hg. Mean rise in the PcCO₂ during bronchoscopy was 9.5±5.3 mm Hg. Mean PcCO₂ at the end of bronchoscopy was 44±9 mm Hg. Baseline PcCO₂ and the lowest SpO₂ were significantly associated with peak PcCO₂ and the change in PcCO₂ during bronchoscopy. Risk of significant hypoxemia (90%) was lower for a higher baseline SpO₂. Peak PcCO₂ was directly associated with significant hypoxemia. There was no significant association in the baseline PcCO₂, peak PcCO₂, baseline SpO₂ or the lowest SpO₂ comparing patients with and without COPD.

It is feasible to measure combined oximetry and PcCO₂ effectively to monitor ventilation during flexible bronchoscopy.