Nebulized Ketamine Plus Standard Care vs. Standard Care Alone in Moderate to Severe Asthma Exacerbations

The goal of this clinical trial is to learn if nebulized ketamine helps treat moderate to severe asthma attacks in adults in the emergency department. It will also learn about the safety of ketamine when inhaled through a nebulizer. The main questions it aims to answer are: * Does nebulized ketamine improve breathing more than standard treatment alone? * What side effects, if any, do participants experience after receiving nebulized ketamine? Researchers will compare nebulized ketamine to a placebo (a saltwater mist with no medication) to see how well it works and how safe it is. Participants will: * Receive either nebulized ketamine or a placebo mist, along with standard asthma treatment * Have their breathing checked before and after treatment using a peak flow meter * Be monitored for 60 minutes and have their symptoms, vital signs, and any side effects recorded