Canadian Anaesthetists’ Society Journal

, Volume 17, Issue 4, pp 370–377 | Cite as

Lung mechanics and blood gases during anaesthesia with spontaneous respiration

  • Ney L. Louzada
  • Davy Trop


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 Cdyn, Qs/Qt, and aaDo2. Induction of anaesthesia resulted in a significant fall in Cdyn, but no alteration in Qs/Qt. There were no changes in Cdyn, Qs/Qt, and aaDo2 up to 96 minutes after induction. Cdyn returned to preoperative values during the recovery period, and Qs/Qt and aaDo2 remained unaffected.

The fall in Cdyn was probably due to a change in the time constants of the different parts of the lungs. The concomitant and probably proportional decrease in Qt and Vo2 seems a valid explanation for the lack of changes in Qs/Qt. Thirteen out of sixteen patients, however, showed an increased Qs/Qt late after induction, when values were compared with the preinduction ones. A closure of some units is thus suggested.


Atropine CANADIAN Anaesthetist Lung Mechanic Cao2 Spontaneous Respiration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Les valeurs de compliance pulmonaire et des gaz sanguins furent relevées chez 20 patients anesthésiés pour des examens angiographiques cérébraux. Les observations commencèrent avant toute prémédication et se poursuivirent jusqu’à la période du réveil dans chaque cas.

Ľinjection intraveineuse ďatropine n’eut aucun effet sur la compliance dynamique, le shunt ou le gradient alvéolo-capillaire. Ľinduction anesthésique provoqua une diminution de la compliance, mais n’affecta pas le shunt. Les valeurs de la compliance, du shunt et du gradient alvéolo-capillaire, relevées après 96 minutes ďanesthésie, ne présentèrent aucune altération subséquente. Au réveil, la compliance redevint normale, tandis que le shunt et le gradient restaient inchangés.

La diminution de la compliance est imputable aux variations de constante de temps à ľintérieur des poumons. Les changements simultanés et parallèles du débit cardiaque et de la consommation ďoxygène fournissent une explication satisfaisante à ľabsence de variation observée dans le shunt.

Treize patients sur seize cependant présentèrent une augmentation du shunt lorsque les valeurs peranesthésiques furent comparées aux valeurs de contrôle. Ceci semble indiquer la fermeture de certains segments pulmonaires.


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Copyright information

© Canadian Anesthesiologists 1970

Authors and Affiliations

  • Ney L. Louzada
  • Davy Trop
    • 1
  1. 1.Department of Anaesthesia, Montreal Neurological Hospital and InstituteMcGill UniversityMontreal

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