Remifentanil and Laryngeal Reflex Responses in Pediatric Patients With URI

To describe respiratory and laryngeal responses to laryngeal stimulation during propofol anesthesia in children with upper airway infections. To determine whether the co-administration of remifentanil blunts these reflex responses. To test whether the co-administration of remifentanil results in a significant reduction of apnea with laryngospasm in these patients. Hypotheses: I: In children with a URI undergoing anesthesia with propofol, the incidence of apnea and laryngospasm after controlled stimulation is expected to occur 2.5 times more frequently than in children without URI (20 vs. 8%). II: The incidence of apnea and laryngospasm is diminished after administration of remifentanil.