Evaluation of transcutaneous carbon dioxide and saturation monitoring during fiberoptic bronchoscopy

Introduction: The aim of the study was to assess the effects of interventions during bronchoscopy on ventilation and determine the risk factors for hypoventilation related to both interventions and patients' demographical and clinical characteristics. Materials and Methods: A total of 74 patients who underwent fiberoptic bronchoscopy (FOB) were included in the study. Oxygen saturation (SpO(2)) and partial carbon dioxide pressure (PCO2) were measured transcutaneously (TcSO2 and TcPCO2) using a sensor consisting of a probe placed on the earlobe. The demographic characteristics and basal, mean, peak and minimum values of TcSO2 and TcPCO2 during FOB were retrospectively analyzed and assessed in terms of the risk factors for hypoventilation. Results: During the procedure, the device automatically recorded the TcSO2 and TcPCO2 values. The mean TcPCO2 level was 37.09 +/- 5.6 (27.1-60.6) mmHg. The mean increase in the TcPCO2 level from baseline was 3.25 +/- 2.12 mmHg. The mean TcSO2 measurement was 95.9 +/- 2.27 (80-100%). The measured mean and peak TcPCO2 values were significantly higher in men. In the whole group, the patients with a history of smoking more than 20 pack-years also had significantly higher TcPCO2 values compared to the nonsmokers and light smokers. In the patients with endobronchial lesions, the decrease in the TcSO2 level was higher during FOB (p= 0.03), and the mean difference between the lowest and mean TcSO2 levels was significantly greater (6.2 vs 4.55%, p= 0.03). Conclusion: Changes in ventilation during FOB have multifactorial causes. The best indicator of ventilation is PCO2, and monitorization of PCO2 is very important in detecting hypoventilation. In this study, we determined some risk factors for hypoventilation in order to predict ventilation problems in patients planned to undergo FOB. We recommend that in male patients with endobronchial lesions, those with a longer smoking history, and those with a longer duration of FOB, SpO(2) should be monitored together with PCO2.