The invention relates to a manifold (100) for a closed system (1) for endotracheal ventilation and aspiration of a patient, having a first section (115) and a second section (145), an opening (112) configured for allowing influx of a flushing medium to the first section (115), and a passage (118) configured for allowing advancement of the catheter from the first section (115) and into the second section (145). The invention is characterised by a valve body (132) arranged interiorly of the first section (115) and configured for optionally allowing blocking of the passage (118) in a first position and of the opening (112) in a second position.