Re-expansion of the collapsed lung with room air mitigates oxidative stress injury following one-lung ventilation during esophageal cancer resection

Objective To determine whether re-expansion of the collapsed lung with room air can attenuate oxidative stress injury following one-lung ventilation during esophageal cancer resection. Methods Twenty-four ASA Ⅰ or Ⅱ patients aged 40-60 yr weighing 44-65 kg undergoing esophageal cancer resection were randomly divided into 2 groups (n=12 each) : room air group and pure oxygen group. Anesthesia was induced with midazolam, fentanyl, etomidate and atracurium and maintained with propofol and atracurium infusion and intermittent iv boluses of fentanyl. Right or left side double-lumen catheter (Fr 35, 37, 39) was inserted in each patient. Correct placement was verified by fiber-optic bronchoscopy. The patients were mechanically ventilated ( V_T 7-10 ml/kg, RR 12-16 bpm, FiO_2 1.0 during one-lung ventilation). P_(ET)CO_2 was maintained at 35-45 mm Hg. SpO_2 was maintained at 95%-100% during one-lung ventilation. Blood samples were collected at the beginning of one-lung ventilation (T_1 ), immediately before re-expansion of the collapsed lung (T_2) and 30 rain after re-expansion of the collapsed lung (T_3) for determination of serum levels of MDA, SOD and plasma level of protein carbonyl. Arterial blood samples were obtained at 2 h after operation for blood gas analysis. Results The plasma protein carbonyl level and serum MDA level were significantly increased while the serum SOD level was significantly decreased at T_3 as compared with thost at T_1 and T_2 in pure oxygen group. No significant change in serum levels of MDA, SOD and plasma level of protein carbonyl occurred during operation in room air group. The oxygenation index was significantly higher at 2 h after operation in room air group than in pure oxygen group. Conclusion Re-expansion of the collapsed lung with room air can attenuate the oxidative stress injury following one-lung ventilation during esophageal cancer resection. Key words: Air;  Oxidative stress;  Lung;  Respiration, artificial;  Esophageal neoplasms