There is an article in the January issue of Anesthesia & Analgesia that warns that patients with sleep apnea have more frequent pulmonary complications after orthopedic and general surgery. I am not sure if this included sleep apnea patients that were treated. The risk of being intubated and put on a mechanical ventilator went up five-fold after orthopedic surgery and two-fold after general surgery. Other complications that were increased after these surgeries included aspiration pneumonia (lung infection after stomach contents are inhaled) and pulmonary embolus (lung clots).
This study points to the importance of pre-surgical screening for sleep apnea, so that anesthesiologists and surgeons are aware of the risk. Also, it would be interesting to know if treating sleep apnea reduces these pulmonary risks.