<prompt> All the following features are seen in ARDS exceptPulmonary oedemaReudced lung complianceHypercapniaStiff lung  <response>: ARDS, the presence of alveolar and interstitial fluid and the loss of surfactant can lead to a marked reduction of lung compliance. Without an increase in end-expiratory pressure, significant alveolar collapse can occur at end-expiration, with consequent impairment of oxygenation. In most clinical settings, positive end-expiratory pressure PEEP is empirically set to minimise Fio2inspired O2 percentage and maximize Pao2aerial paial pressure of O2. On most modern mechanical ventilators, it is possible to construct a static pressure-volume curve for the respiratory system.The impact of hypercapnia in ARDS. The impact of hypercapnia has not been clearly elucidated and is still controversial given its disparate effects . Neveheless, it has come to be seen as a major factor in ARDS Ref Davidson edition23rd pg 199 