Methods: The study included 45 patients (24 males, 21 females; mean age 54.6±7.7 years; range, 18 to 65 years) with an American Society of Anesthesiologists risk group of 1 to 2 and scheduled for elective thoracotomy. Patients were randomly divided into three groups as those due for thoracotomy without one-lung ventilation (group 1, n=15), those due for thoracotomy with one-lung ventilation (group 2, n=15), and those due for thoracotomy in whom both lungs were ventilated (group 3, n=15). Blood specimens were collected for ischemia-modified albumin, malondialdehyde, and lactate measurements one minute before one-lung ventilation (t0), 30 minutes after one-lung ventilation (t1), 60 minutes after one-lung ventilation (t2), and at postoperative 24th hour (t3). For group 1, t0 was defined as the time at which the thorax was opened.

Results: A statistically significant increase in ischemia-modified albumin, malondialdehyde, and lactate levels occurred in group 2 as the duration of one-lung ventilation increased (p<0.01). Plasma ischemia-modified albumin and malondialdehyde levels in group 3 were statistically significantly lower at t1, t2, and t3 compared with group 2 (p<0.01). Plasma lactate levels were significantly lower in group 3 at t1 (p<0.05) and t3 compared with group 2 (p<0.01).

Conclusion: Separate ventilation of the non-ventilated lung with low tidal volume and high frequency reduces the response to one-lung ventilation-associated oxidative stress in thoracic surgery.