Respiratory muscle training

Hello everyone i was wondering if somebody is using or use to do respiratory training.I have asthma and when i first started to do pursed lip breathing i stoped coughing and i had much less mucus-i was feeling much better in general.Can someone tell me how are your results,because i bought recently one of this device to train my respiratory muscles and my asthma is much much better after 1 month only.I trully belive that the CO2 is the stongest bronchodilator and vasodilator.So can anyone explain what is going on with my body?The same think ive heard from the people who are playing some wind instruments-same type of air resistance...there has to be something to it.Anyone?Thanks