A prospective, randomized, patient-blinded comparison of the safety and efficacy of conscious sedation by propofol/alfentanil with propofol/ketamine in patients undergoing flexible fiberoptic bronchoscopy.

The study group will include 80 patients undergoing flexible fiberoptic bronchoscopy(FFB).

Patients will be randomly assigned prior to the procedure to receive sedation by either propofol/alfentanil (PA group) or propofol/ketamine (PK group), using either the sealed envelope method or by computer randomization.

All patients will receive local anesthesia with Lidocaine 2% (total dose of 5-10 ml) that will be sprayed via the bronchoscope on the vocal cords before passage through them, as well as into the bronchial tree in order to suppress coughing.

In addition, patients from both groups will optionally receive intravenous Midazolam (up to a total dose of 0.05 mg/kg)if deemed necessary during the procedure.

Sedation will be started by 10-15 mcg/kg Alfentanil and 0.4 mg/kg Propofol, or by 0.2-0.3 mg/kg Ketamine and 0.4 mg/kg Propofol. It will be maintained by additional boluses of Propofol (aliquots of 10-50 mg) or by additional boluses of Propofol (aliquots of 10-50 mg) and/or Ketamine (aliquots of 5-25 mg).

All patients will receive supplemental oxygen via nasal cannula (2-4 L/min) before the beginning of the procedure.

Patients whose functional oxygen saturation (SpO2) prior to the beginning of the procedure will be lower than 92% while connected to a nasal cannula, will receive oxygen supplementation via a face mask.

If the SpO2 after initiation of sedation will fall below 90%, the patients' airways will be opened using a jaw-thrust maneuver or insertion of a nasal airway. Should the SpO2 remain low, the patient will receive oxygen supplementation via a face-mask.

If deemed necessary, additional safety measures will be taken by the anesthesiologist or by the performer of the bronchoscopy, such as administration of oxygen directly through the bronchoscope, assisted ventilation with an Ambu bag, and tracheal intubation.

The duration of bronchoscopy will be calculated from the administration of sedation until the flexible bronchoscope is removed from the tracheobronchial tree.

In all cases, patients will be monitored using continuous electrocardiography, pulse oximetry, and transcutaneous carbon dioxide (PtCO2, using a digital sensor placed on the patient's earlobe),and automated noninvasive blood pressure recordings every 5 minutes. All parameters will be recorded beginning from prior to connecting the patient to the nasal cannula before initiation of sedation, throughout the entire procedure and until 10 minutes after removal of the bronchoscope from the nasopharynx.

Immediately after the end of the procedure, the bronchoscopist will grade the quality of sedation (ease of performing the procedure) by Visual Analog Scale.

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

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

Inclusion Criteria:

• American Society of Anesthesiologists grade I or II
• patients that will be referred to the procedure for bronchoalveolar lavage and cytologic/bacteriologic sampling, endoluminal biopsies for pathologic /bacteriologic analysis, or for regaining patency (mechanically or laser-assisted) of airways that are obstructed by secretions, tumors or foreign bodies

Exclusion Criteria:

• patient refusal or inability to provide informed consent
• American Society of Anesthesiologists grade III or higher
• allergy to study medications
• patients who have an endotracheal tube or tracheostomy