Respiratory gas conditioning is important to protect the lungs and is a universal standard of care. Cold and dry respiratory gases reduce ciliary activity in the respiratory epithelium. The reduction of mucociliary clearance can lead to atelectasis and infections, conditions referred to as postoperative pulmonary complications. Various studies demonstrated, that protective ventilation approaches allow the reduction in incidence of postoperative pulmonary complications (PPC). Warming and humidifying the respiratory gases using lowflow anaesthesia can reduce these negative effects on the respiratory epithelium.