The midazolam and fentanyl versus additional use of propofol in difficult-to-sedate cases during bronchoscopy by transcutaneous gas monitoring: a case control study

Background: bronchoscopy is a relatively invasive procedure, and standard anesthesia is often inadequate. The recently introduced transcutaneous carbon dioxide (tcpCO2) monitoring has become a convenient surrogate method for continuous monitoring of the partial pressure of arterial carbon dioxide (PaCO2). The objective of this study was to evaluate the safety of additional use of propofol during bronchoscopy by transcutaneous blood gas monitoring. Methods: patients in whom transcutaneous gas monitoring was performed during bronchoscopy were included in this study. The study subjects were divided into two groups: 1) the midazolam + fentanyl group (MF group), and 2) the group in which midazolam was switched to propofol because of inadequate sedation with midazolam + fentanyl (MFP group). We conducted a retrospective analysis of the transcutaneous gas measurement data obtained during bronchoscopy. Results: data of a total of 61 patients (MF group, n=41; MFP group, n=20) were analyzed. The duration over which the tcpCO2 remained over 50 mm Hg was longer in the MFP group (MF 0.0 min vs. MFP 7.8 min, p=0.042). The percentage of patients in whom the tcpCO2 rose to over 50 mm Hg was also higher in the MFP group (MF group, 14.6% vs. MFP group, 65.0%). None of the patients required discontinuation of the bronchoscopic procedure due to inadequate sedation. Conclusions: while the addition of propofol improved the tolerability of the procedure in difficult-to-sedate patients, it was also associated with a higher risk of ventilatory failure and hypoxemia. Thus, in order to ensure safety, additional propofol should be used with caution under continuous pCO2 monitoring, such as by transcutaneous measurement. Trial registration: this study was conducted with the approval of the Clinical Research Management Division of Dokkyo Medical University (Approval No.: R-15-5J) under the supervision of a well-trained bronchoscopist. The contents of the study were disclosed in an opt-out format.