<prompt> Side effect of alfentanil:Chest wall rigidityHypertensionConvulsionHallucination  <response>: Ans. a Chest wall rigidityRef : Millers Anaesthesia 7th ed. 806 Alfentanil is a short-acting synthetic opioid analgesic drug, used for anaesthesia in surgery. It is an analogue of fentanyl, with lower potency. Most adverse side effect: Chest wall rigidity, followed by others like respiratory depression, arrhythmia, Bradycardia, hypertension, blurred vision etc.Also Know Remifentanyl, Alfentanyl Sufentanil have short duration of action so can be used as outpatient anesthetic agents Best anesthetic agentfor OPD patients: Alfentanyl 