@wangling Another thought -- what other medication do you take for bronchiectasis? Anything OTC?

Asking because I restarted mucinex recently. Again when taking it, I find I can never completely clear my airways. There's always a rattle and/or wheeze. My breathing test at the allergist this week was so bad! After a day or more of stopping mucinex my breathing and spo2 returned to normal for me.

It makes sense that when one is breathless (lower spo2) heart rate increases because heart is working harder to pump more.