Breathing assistance apparatus

A gases modification unit for use as part of a breathing assistance system configured to provide heated humidified gases through a conduit to a user at a positive pressure for therapeutic purposes, comprising:

• an outer casing having an inlet vent or inlet port configured to admit gases into said outer casing in use, and an outlet port adapted for connection to said conduit in use, said outlet port configured to convey gases into said conduit, said inlet port and said outlet port connected by a gases path within said outer casing;
• electronic circuitry enclosed within said outer casing, said electronic circuitry adapted to provide at least one control signal configured to modify at least one property of gases passing along the gases path;
• and
• a conduit connection display which is adapted to indicate to a user that said conduit is correctly connected to said outlet port,
• wherein said gases modification unit is configured to establish that said conduit is correctly connected to said outlet port by receiving at least one signal indicative of air flow through said gases path and air pressure within said gases path, and confirming at least one stored value correlates with (i) the air flow through said gases path and (ii) the air pressure within said gases path.