Nebulized ketamine (0.5 mg/kg in normal saline to a total volume of 5ml) plus standard asthma excaerbationcare
Drug**Intervention Description:** Nebulized ketamine is administered as a single dose of 0.5 mg/kg of ketamine hydrochloride diluted in 0.9% normal saline to a total volume of 5ml. The solution is delivered via a standard jet nebulizer over approximately 15-20minutes. This intervention is given once at the time of enrollment in the emergency department, in addition to standard asthma care. The ketamine used is in injectable solution form (typically 50 mg/mL concentration), drawn and diluted immediately prior to nebulization. Participants are monitored continuously for 60 minutes after administration to assess changes in peak expiratory flow rate (PEFR), symptom relief, and adverse events. The goal is to evaluate the bronchodilatory effect and safety of nebulized ketamine in adults with moderate to severe asthma exacerbation who present to the emergency department.