The literature does not currently describe which ventilation changes a clinician should watch for to keep a patient safe during procedural sedation provided by fentanyl and propofol. This observational study aimed to record the breath-by-breath respiratory rate, tidal volume and end-tidal CO2 for each patient during procedural sedation for each endoscopy procedure. Data analysis offline will aim to identify any patterns in ventilation which may precede apnea or blood oxygen desaturation. The patterns in ventilation preceding apnea or blood oxygen saturation will be compared and contrasted with the patterns of ventilation during normal ventilation periods.