A Randomized Study Comparing of Three Doses Nebulized Fentanyl in Older Adults

This clinical trial compares three different nebulized fentanyl dosages for older persons experiencing severe musculoskeletal pain at the emergency department. The main objective is: Does the effectiveness of nebulized fentanyl at dosages of 2 mcg/kg, 3 mcg/kg, and 4 mcg/kg at 30 minutes differ in older patients who report to the emergency room with pain from musculoskeletal injuries? Secondary outcome are: 1. Incidence of adverse effects after drug administration at minutes 0, 15, 30, 45, 60, 75, 90, 105, 120 2. Incidence of receiving other pain relief treatments (rescue therapy) in minutes 30, 45, 60, 75, 90, 105, 120 Participants will receive an explanation of the study and possible side effects, which may take approximately 5-10 minutes, without affecting the primary treatment of the patients. Consent will be obtained in this study, along with signing or fingerprinting as evidence in the consent form.

Inclusion Criteria: * Age more than or equal 65 years old. * Presented with musculoskeletal pain within 3 days. * Pain score on verbal numeric rating scale ≥ 5. Exclusion Criteria: * Patients need immediate intervention. * Patients need acute rescue for acute coronary syndrome, respiratory failure, and stroke. * Creatinine clearance \< 30 ml/min, Cirrhosis stage III, IV (present with ascites and varices). * Trauma \>2 organ. * Comorbidities of chronic obstructive pulmonary disease. * Take MAO inhibitors within 14 days. * History of opioid used within 8 hours. * History of alcohol or drug abuse. * History of fentanyl allergy. * Patients with difficulty to communication (e.g. altered mental status, severe dementia (define by 6-items cognitive screening \> 12, language barrier).