Canadian Journal of Anesthesia, Vol 29, 600-611, Copyright © 1982 by Canadian Anesthesiologists' Society

Effets Ventilatoires de Debits Croissants D'Alfatesine Chez le Chien

¹ Laboratoire d'anesthésiologie, Hôpital Rothschild 33, bd de Picpus 75012 PARIS. Département d'anesthésie Hôpital Saint-Antoine (Pr. C. Guilmet)

In 10 dogs the authors studied the effects of increasing doses of alfathesin on ventilation (V^·E, frequency, VT, blood gases), on the ventilatory pattern (TI, TE, TI/T_tot), on the neurological initiation of ventilation (VT/TI, occlusion pressure at 0.5 seconds), and on the Hering-Beurer reflex (duration of apnoea after occlusion of the airway at the end of inspiration). The results were compared with normal values taken from the literature. The correlation between the dose of alfathesin and the measured or calculated parameters was examined.

Ventilation was stimulated by low doses of alfathesin, a stimulation characterized by tachypnoea without change in tidal volume. Deepening of anaesthesia was accompanied by progressively increasing depression of respiration (diminution of V^·E, of frequency, of VT/TI and increase of Paco₂ and of the duration of apnoea).

The mechanisms of the initial stimulation of ventilation and of respiratory depression are discussed.

The authors conclude that the action of alfathesin on the central nervous system is biphasic, with stimulation during light anaesthesia followed by depression with associated depression of ventilation, despite increasing hypoxia and hypercapnia.