Laryngeal Paralysis is very common in senior Labs. The best thing you than do is keep them cool and calm.
You do not want to over exercise them or let them get over heated. This will cause them difficulty with breathing.
There is really no that much you can do....sometimes surgery is recommended for severe cases...but it does come with a high risk of complications.
Vets will also sometimes prescribe anti-anxiety medications or anti-inflammatory meds to help the condition.
It is good that your Lab is having tests to confirm the diagnosis....Please keep us posted.