Canadian Journal of Anesthesia, Vol 17, 370-377, Copyright © 1970 by Canadian Anesthesiologists' Society

Lung Mechanics and Blood Gases During Anaesthesia with Spontaneous Respiration

¹ Department of Anaesthesia, Montreal Neurological Hospital and Institute, McGill University, Montreal

Lung mechanics and blood gases were studied throughout the course of anaesthesia in 20 patients undergoing cerebral angiographic procedures. Measurements started before premedication and continued into the recovery period, each subject acting as his own control.

Premedication (0.015 mg/kg atropine) did not affect C_dyn, Q^·s/Q^·t, and AaDo₂. Induction of anaesthesia resulted in a significant fall in C_dyn, but no alteration in Q^·s/Q^·t. There were no changes in C_dyn, Q^·s/Q^·t, and AaDo₂ up to 96 minutes after induction. C_dyn returned to preoperative values during the recovery period, and Q^·s/Q^·t and AaDo₂ remained unaffected.

The fall in C_dyn was probably due to a change in the time constants of the different parts of the lungs. The concomitant and probably proportional decrease in Q^·t and V^·o₂ seems a valid explanation for the lack of changes in Q^·s/Q^·t. Thirteen out of sixteen patients, however, showed an increased Q^·s/Q^·t late after induction, when values were compared with the preinduction ones. A closure of some units is thus suggested.

Note:

Presented at the 1969 Annual Meeting of the Canadian Anaesthetists' Society. This study was supported in part by research grant 690044 from the Conseil de la Recherche Médicale du Quebec, and grant 68/274-69/446 from FAPESP-SSO Paulo. This paper forms part of Dr. Louzada's M.SC. thesis for the Department of Experimental Medicine, McGill University