How is this for service...a response within 15 minutes of posting? Hopefully....a useful response as well...
In answer to your question, salivary issues of all kinds are very common in PALS, and vary significantly from one PALS to another. Additionally....in an individual PALS, such as your wife, the specific salivary issues often change within the course of the disease. You noted that your wife has a G - tube and it sounds like you gave hean expectorant (a medication that, as you noted, 'thins' salivary excretions). I am the primary caregiver for my mother, who was officially diagnosed in 2/2016. For some time, we have been dealing with somewhat alternating salivary issues. Specifically...at times, her issues are similar to those you describe, thick saliva that is difficult to clear, resulting in 'uncomfortable and scary' choking episodes. At other times, it appears as if a saliva faucet has been turned on, and lacking the facial musculature necessary to form a seal with her mouth - this can lead to embarrassment (from her perspective) in public and in any situation, inconvenience. Fortunately (something that can only be thought of this way in PALS and others with similar issues...) we are headed to the hospital tomorrow, where she will have a G - Tube port placed, and possibly a diaphragmatic pacer as well. I bring all this up to say that, in PALS and everyone else, the degree to which an expectorant 'thins' secretions is directly related to a patients hydration status. Since most work by increasing the water content of the secretions....no H20, no thinning. Finally, in my mom's case, a few different meds have been used at times, to treat salivary issues. For those times when it seems like the faucet has been turned on, she was given 'atropine drops'....which she would use by putting one or two drops under her tongue. This medication is indicated for ocular issues....but 'dry mouth' is one of the side effects....which is taken advantage of in PALS. Besides tasting terrible, it was difficult to gauge how much she was putting under her tongue - and most of the time - the dry mouth was worse then the salivation. She has been on Neudexta for some time. This med is typically used for 'pseudobulbar affect' issues (heightened emotional responses to issues/situations that did not provoke these responses in the past) - but it also helps with excess salivation and drooling.
As usual, I have written much more then I intended to. I hope it was possible to locate my responses to your specific questions within all the other stuff. If not - adequate hydration would have served as an adequate response.... but, oh well...
Paul