some doctors are asking ventolin and atrovent solutions can mix togather or not?, via misty nebuliser. If yes, how much dosage, or is any standard protocal available kindly some one reply me, thanks

We do it all the time. I have mixed 2.5 mg Albuterol with 0.5 mg Atrovent (and add saline if one or both not in a unit dose)

"Duoneb" is essentially this (Albuterol is technically 3.0mg though).