Thirty patients of the American Society of Anesthesiologists ( ASA ) I and II were randomly allocated into @ groups : G@ ( n = @ ) patients received general anesthesia and were mechanically ventilated with @ mL/kg during @ lung ventilations , reduced to @ mL/kg and @cm H@O positive end expiratory pressure ( PEEP ) during one lung ventilation ( OLV ) or GII ) ( n = @ ) patients received TEA and the same general anesthesia and mechanical ventilation used in G@ .