A medical gas blending system includes a first syringe configured to be connectable to a supply of a first gas, and a second syringe configured to be connectable to a supply of a second gas. A three-way valve is provided between the first syringe and the second syringe. The three-way valve is operable in a first configuration to selectively isolate the first syringe from the second syringe, in a second configuration to allow communication between the first syringe and the second syringe, so that the first gas present in the first syringe and the second gas present in the second syringe may be selectively blended in the first syringe and/or the second syringe to form a blended gas mixture, and in a third configuration so that the blended gas mixture may be transferred from the first syringe and/or the second syringe to an external syringe connectable to the three-way valve.
