Hi anniewi, and thanks for your post. As you are probably aware, nasal cannulas, as with most disposable, single-patient use respiratory therapy devices, are not supposed to be re-used or cleaned. Having said that, there is a distinct difference when using these types of devices at home by one person.
To answer your question, I thought you might want to look over these two articles from our COPD.net website.
First, this one, on the care and cleaning of oxygen equipment: https://copd.net/living/cleaning-oxygen-equipment/, (please note the section on nasal cannula), and,
next, this one , on cleaning your devices: https://copd.net/topic/cleaning-your-devices/, (please take note of all the replies to the initial post).
I think both of these article will provide you with some answers for your concern.
Wishing you well,
Leon (site moderator COPD.net)