How to check if the inhalation with the inhalation chamber has been done correctly?

The information in the wording of the question is not sufficient to assess whether a further dose is necessary in this case. If you have a model of the AeroChamber Plus Flow-Vu chamber, it is worth paying attention to the Flow-Vu sensor. If the mask is correctly attached, the Flow-Vu indicator moves as you inhale and exhale. If the "cooperation" with the child during the administration of the drug is difficult (the child cries, pulls out), it is allowed to give the drug to the child during sleep. The medicine should be given to the child in a semi-reclining position, e.g. on the parent's lap, ensuring that the mask fits snugly to the child's face. If in doubt, seek the advice of your pediatrician: https://www.gdziepolek.pl/telekonsultacja/z-pediatra