A measuring head for the analysis of respiratory gases to and from a patient connected to a respirator, includes an aperture (7) which is intended to be placed over an adapter (2) through which respiratory gases flow. The measuring head (1) has a light transmitter (9) which includes an IR-emitter (12) on one side of the aperture (7) and a light receiver (10) which includes an IR-detector on the other side of the aperture (7). The measuring head (1) also includes a signal processing unit (20) necessary for the gas analysis.