[Changes in the parameters of respiratory mechanics after the aspiration reflex and asphyxia]

Parameters of respiration mechanics (dynamic compliance--Cdyn and total lung resistance--RL), ventilation, blood gases, and right-to-left pulmonary shunts were studied after aspiration reflex in experiments on 29 anesthetized cats. Attacks of aspiration reflex were induced without asphyxia (8 cats) and during two-minute asphyxia (9 cats). The control group consisted of 12 animals. A series of aspiration reflex attacks resulted in short-term improvement of the parameters of respiration mechanics with an increase in Cdyn and reduction of RL. A simultaneous elevation of PaO2 and a decrease of PaCO2 were recorded. In combination with asphyxia (hypoxemia and hyperkapnia), the aspiration reflex induced a reversed reaction, i.e. decreased Cdyn lasting till the end of experiment (3 hours) and an increase of functional alveolar right-to-left shunts. The results indicate that in cats impairment of respiration mechanics parameters is brought on only when deep inspiration is combined with asphyxia.