['Left-sided double-lumen tubes are perceived to be safer than right-sided tubes, because they may be less prone to malposition. If this is true, then the incidence and severity of hypoxemia, hypercapnea, and high airway pressures should be higher for right-sided tubes during thoracic surgery than for left-sided tubes.', 'We retrospectively reviewed thoracic surgical anesthetics between April 15, 2003, and December 31, 2004, using an automated anesthesia information management system. The system automatically records pulse oximetry, end-tidal carbon dioxide, and peak inspiratory pressure data every 30 s. Side of surgery and double-lumen tube placement are also documented. We compared the frequency of right- and left-sided Mallinckrodt tube use by thoracic anesthesiologists. Next, we examined the incidence, duration, and severity of hypoxemia (Spo(2) <90%), hypercapnea (Etco(2) >45 mm Hg) and high airway pressures (peak inspiratory pressure >35 cm H(2)O) for lung and chest wall surgery patients. Group counts and means were compared by standard statistical methods.', 'Right- (n = 241) and left- (n = 450) sided tubes were almost exclusively used on the side contralateral to surgery. There were no differences in the incidence or duration of hypoxemia, hypercarbia, or high airway pressures. There was a small but significant increase in Etco(2) for patients having left lung ventilation.'] Do right- and left-sided Mallinckrodt double-lumen tubes have identical clinical performance?