Transcutaneous carbon dioxide in severe COPD patients during bronchoscopic lung volume reduction

Summary Background Patients undergoing bronchoscopy are usually monitored only by pulse oximetry, hence hypoventilation cannot be assessed. Transcutaneous carbon dioxide tension (Tc P CO 2 ) monitoring is a non-invasive technique to assess hypoventilation. Patients with severe chronic obstructive pulmonary disease (COPD) undergoing bronchoscopy are at increased risk for sedation-induced hypoventilation. The aim of the study was to measure Tc P CO 2 using a digital sensor to examine the occurrence of hypoventilation during bronchoscopic lung volume reduction (BLVR). Methods Combined Tc P CO 2 and SpO 2 saturation and arterial blood gases (ABG) were prospectively measured in 15 patients with severe COPD (Mean FEV 1 29%) undergoing BLVR under conscious sedation with IV midazolam and IV alfentanil. Results A highly significant correlation was noted between simultaneous ABG P CO 2 samplings and Tc P CO 2 measured ( R  = 0.85, p P CO 2 level was 41.7 ± 10.3 mm Hg (±SD) (range 35–66 mmHg)], and peak measurement during the procedure was 61 ± 17.1 mm Hg (range 41–111 mmHg). The mean increase in Tc P CO 2 during bronchoscopy was 19.2 (range 3.7–45 mmHg) [ p P CO 2  > 55 mmHg), observed in 7 (46%) patients, was 9 min (range 0–53). Conclusions Bronchoscopy performed under conscious sedation in patients with severe COPD is frequently associated with significant hypoventilation that can only be detected by Tc P CO 2 monitoring. Combined measurement of SpO 2 and Tc P CO 2 during bronchoscopy enhances patient safety, helps guide administration of sedation, and can alert physicians to the need for anesthesia reversal following completion of bronchoscopic interventions.