Hypercapnia in COPD Patients Undergoing Endobronchial Ultrasound under Local Anaesthesia and Analgosedation: A Prospective Controlled Study Using Continuous Transcutaneous Capnometry

Abstract

<b><i>Background:</i></b> Flexible bronchoscopy (FB) in analgosedation causes alveolar hypoventilation and hypercapnia, the more so if patients suffer from COPD. Nonetheless, neither is capnometry part of standard monitoring nor is there evidence on how long patients should be monitored after sedation. <b><i>Objectives:</i></b> We investigated the impact of COPD on hypercapnia during FB with endobronchial ultrasound (EBUS) in sedation and how the periprocedural monitoring should be adapted. <b><i>Methods:</i></b> Two cohorts of consecutive patients – with advanced and without COPD – with the indication for FB with EBUS-guided transbronchial needle aspiration in analgosedation received continuous transcutaneous capnometry (p_tcCO₂) before, during, and for 60 min after the sedation with midazolam and alfentanil. <b><i>Main Results:</i></b> Forty-six patients with advanced COPD and 44 without COPD were included. The mean examination time was 26 ± 9 min. Patients with advanced COPD had a higher peak p_tcCO₂ (53.7 ± 7.1 vs. 46.8 ± 4.8 mm Hg, <i>p</i> &#x3c; 0.001) and mean p_tcCO₂ (49.5 ± 6.8 vs. 44.0 ± 4.4 mm Hg, <i>p</i> &#x3c; 0.001). Thirty-six percent of all patients reached the maximum hypercapnia after FB in the recovery room (8 ± 11 min). Patients with COPD needed more time to recover to normocapnia (22 ± 24 vs. 7 ± 11 min, <i>p</i> &#x3c; 0.001). They needed a nasopharyngeal tube more often (28 vs. 11%, <i>p</i> &#x3c; 0.001). All patients recovered from hypercapnia within 60 min after FB. No intermittent ventilation manoeuvres were needed. <b><i>Conclusion:</i></b> A relevant proportion of patients reached their peak-pCO₂ after the end of intervention. We recommend using capnometry at least for patients with known COPD. Flexible EBUS in analgosedation can be safely performed in patients with advanced COPD. For patients with advanced COPD, a postprocedural observation time of 60 min was sufficient.