Heart rate ( HR ) , mean arterial pressure ( MAP ) , measured tidal volume ( TV ) , peak airway pressure ( Ppeak ) , airway resistance ( Raw ) , chest compliance ( Cdyn ) and the end-tidal carbon dioxide pressure ( PetCO ( 2 ) ) were recorded at the time point of 15 minutes after turning to the lateral position , 15 minutes and 60 minutes after OLV , and 15 minutes after the resumption of two lung ventilation .