Two lung ventilation (TLV) will be instituted using fraction of inspired oxygen (FiO2) of 0.4 in air, tidal volume (VT) of 8 mL kg-1, inspiratory to expiratory (I: E) ratio of 1:2.5 and PEEP of 5 cm H2O, and respiratory rate will be adjusted to achieve an arterial carbon dioxide tension (PaCO2) of 4.7-6 kPa. During one-lung ventilation (OLV), the dependent lung will be ventilated with a FiO2 of 1.0, VT of 6 mL kg-1 and I: E ratio, PEEP, and respiratory rate, will be maintained as during TLV. The dependent lung will be recruited at 30-minute intervals by increasing the inspiratory pressure to 40 cmH2O for 10 seconds.