Experiences are presented concerning the use of a computer system in analyzing the dynamics of respiratory changes during reversible respiratory failure induced by inhalation of nitrogen in anesthetized cats. The main focus is on semiautomatic evaluation of the air flow signal during experimentally induced hypoxia in model experiment. On the basis of experience with computer aided evaluation of respiratory changes in over 40 animals and regarding the analysis of actual data obtained from 29 hypoxic episodes leading to reversible respiratory failure in 9 cats, advantages and pitfalls of evaluating respiration parameters by the breath-by-breath method are highlighted. Besides demonstrating the applied computer processing of data, the paper evaluates the most important of the 30 respiratory parameters studied, i.e. tidal volume (VT), minute ventilation (VE), inspiratory time (TI), and the ratios VI/TI and TI/TTOT. The results allow to quantify well the dynamics of development of changes of the respiratory model particularly during the first phase of acute hypoxic hypoxia. (Tab. 1, Fig. 5, Ref. 21).