Abstract
Background and Aim. The majority of patients who undergo bronchoscopy feel anxiety and discomfort. Therefore, most of them prefer to be sedated during this procedure. However, sedation has the risk of complications caused by respiratory depression. The aim of this study was to evaluate the usefulness of transcutaneous CO_2 pressure (PtcCO_2) measurement as a tool for monitoring respiratory condition during flexible bronchoscopy under sedation. Methods. We studied 88 consecutive patients who underwent bronchoscopy. They consisted of 52 men and 36 women of mean age 67.1 years. Bronchoscopy was performed under sedation with intravenous midazolam. Arterial blood gas analysis was done before and during the sedation. During the procedure, patients were given supplemental oxygen and we monitored blood pressure, electrocardiogram, pulse oximetric saturation (SpO_2) and PtcCO_2. Results. The mean baseline PaCO_2 value was 42.8mmHg. Mean change in PaCO_2 measurement from the baseline was 4.9mmHg. Mean increase of PaCO_2 was larger in women than in men. Age, body weight, midazolam dosage per body weight and the pulmonary functional factors which we examined, were all unrelated to the degree of PaCO_2 change. In this examination, PtcCO_2 values demonstrated a high degree of correlation with PaCO_2. Serious complications did not happen in any case in this study, but there were a few cases that showed unexpectedly high PaCO_2 elevation. In this investigation, patients with more than a 15 mmHg elevation of PaCO_2 from the baseline value or critical decrease of SpO_2, had bronchial asthma or obstructive sleep apnea syndrome. Conclusion. Flexible bronchoscopy performed under sedation may cause respiratory depression. PtcCO_2 measurement is useful to non-invasively and continuously evaluate hypoventilation during this procedure.
