How to keep sinuses moist after septoplasty/turbinate reduction?

Unfortunately, your complaint is extremely common.  After this type of surgery the normal function of the nose to humidity the air you breathe is hindered.  Using a CPAP machine makes this much worse. The good news, however, is that the dryness should improve after 2-4 weeks. Using the humidifier on your CPAP machine is a great idea along with the salt water sprays. You can try applying Vaseline to your inner nostrils before bed as well. Keep your scheduled postop appointments to ensure you're healing well, but I would expect things to improve in the near future. Good luck!