Although propofol is a popular agent for sedation during flexible bronchoscopy, some clinicians have raised concerns that it may cause greater respiratory drive reduction than more common drugs. However, this factor is difficult to accurately examine with pulse oximetry. The introduction of a novel device that noninvasively measures carbon dioxide (CO2) levels can help to resolve this controversy. The aim of this study is to evaluate the safety of conscious sedation with midazolam+alfentanil compared to propofol.

Methods: The study group included 115 patients undergoing flexible fiberoptic bronchoscopy(FFB). Patients were randomly assigned by a computer before the procedure to receive sedation with midazolam+alfentanil or propofol. Local anesthesia was induced by application of 2% lidocaine to the oropharynx. Sedation was started with intravenous injection of a bolus of 2-4 mg midazolam and 0.5 mg alfentanil or 20-50 mg propofol. It was maintained with intermittent boluses of 1-3 mg intravenous midazolam or 0.5 mg intravenous alfentanil, according to clinical judgment, or with boluses of 10-20 mg intravenous propofol, administered at short intervals (~2 minutes) or according to clinical judgment.

In all cases, monitoring included continuous electrocardiography, pulse oximetry, and automated noninvasive blood pressure recordings every 5 minutes. In addition, percutaneous carbon dioxide tension (PcCO2) was measured with a cutaneous digital sensor (Sentec AG, Therwil, Switzerland) that was placed on the earlobe prior to the procedure. It was removed when the patient left the bronchoscopy suite.

During the procedure, all patients received supplemental nasal oxygen at 2-5 L min-1. Significant hypoxemia, defined as functional oxygen saturation (SpO2) of 90%, was treated initially with jaw support. If it lasted more than few seconds, a naso/oropharyngeal tube was inserted or supplemental oxygen was delivered via face mask at 10 L min-1. The duration of bronchoscopy was calculated from the administration of sedation until the flexible bronchoscope was removed from the tracheobronchial tree.

Percutaneous carbon dioxide tension, blood oxygenation, heart rate, and blood pressure were compared between the groups.

A questionnaire evaluating pain and discomfort by Visual Analog Scale was completed by the patient when awake after the procedure.(~30 minutes after the end of the procedure

Inclusion Criteria:

• The study group consisted of patients scheduled for flexible bronchoscopy under local anesthesia with sedation at a tertiary medical center.

Exclusion Criteria:

• Inability or refusal to provide informed consent, age less than 18 years, bronchoscopy through an artificial airway, and allergy to soya or to one of the sedative drugs.