A method, device, and computer program product for improving accuracy of a respiratory gas measurement from a subject ventilated at a predetermined respiration rate through a ventilator. A respiratory gas measurement value is acquired within a first expiration period of the subject, thereby to obtain a first measurement value 32. The ventilator is paused for a pause period 31 within a second expiration period of the subject and a respiratory gas measurement is performed within the pause period, thereby to obtain a second measurement value 33. A correction factor 45 is then determined based on the first measurement value 32 and the second measurement value 33 and the correction factor is employed to correct subsequent respiratory gas measurement values obtained from the subject at the predetermined respiration rate, thereby to improve the accuracy of the measurement.
