A respiratory gas conditioning system (190). The system includes an inhale branch (IB), an exhale branch (EB), a heat and moisture exchanger HME (200), and a connector (70) for connecting the branches (IB, EB) to a patient (P). The system (190) comprises an HME (200) located close to a ventilator (60) a water reservoir (RS) located in the exhale or inhale branch to moisture-enrich the gas flowing along the branches (IB,EB).
