This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscle Relaxant, Subject name: Anaesthesia
Side effect of alfentanil: 
Select and explain. 
A. Chest wall rigidity, B. Hypertension, C. Convulsion, D. Hallucination
A: Chest wall rigidity
Answer: A: Chest wall rigidity 
Explanation: Ans. (a) Chest wall rigidityRef : Miller's 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