Download PDF

Canadian Anaesthetists’ Society Journal

, Volume 28, Issue 4, pp 370–372 | Cite as

A simple formula for adjusting arterial carbon dioxide tension

  • H. R. Wexler
  • Peter Lok
Article

Abstract

To improve the accuracy of acid-base adjustment in mechanically ventilated patients we derived the formula: Required minute ventilation =known arterial Pco2 x known minute ventilation/ desired arterial Pco2 which allows calculation of the minute ventilation required to produce a desired arterial Pco2 by measuring the patient’s existing arterial Pco2 and minute ventilation. This was tested in fifty patients using four types of ventilators and found to be statistically accurate, with a mean difference between predicted and observed Pco2 of 0.153 kPa (1.15 torr) ± S.E.M. 0.798.

Key Words

Acid-Base Equilibrium adjustment Ventilation mechanical adjustment formula 

Résumé

Pour améliorer la précision du réglage de l’équilibre acido-basique chez les malades sous ventilation mécanique nous vaons déduit la formule: Ventilation minute requise =Pco2 artériel connu x ventilation minute connue/ Pco2 artériel désiré ce qui permet de calculer la ventilation minute requise pour produire un niveau de Pco2 artériel désiré en mesurant la Pco2 artérielle actuelle du patient et sa ventilation minute. Cette formule a été vérifiée sur 50 patients lors de l’emploi de quatre types de ventilateurs et nous l’avons trouvée statistiquement précise avec une différence moyenne entre la Pco2 prédite et observée de 0.153 kPa(1.15 torr) + S.E.M. 0.798.

Download to read the full article text

References

  1. 1.
    Radford, E.P. Ventilation standards for use in artificial respiration. J. Appl. Physiol.7: 451 (1955).PubMedGoogle Scholar
  2. 2.
    Nunn, J.F. Applied Respiratory Physiology, 2nd Edition. London: Butterworths (1977).Google Scholar
  3. 3.
    Riley, R.L. &Cournand, A. Analysis of factors affecting partial pressures of oxygen and carbon dioxide in gas and blood of lungs. J. Appl. Physiol.1: 825 (1951).Google Scholar
  4. 4.
    Watson, W.E. Observations on physiological dead space during intermittent positive pressure respiration. Br. J. Anaesth.34: 502 (1962).PubMedCrossRefGoogle Scholar
  5. 5.
    Nunn, J.F. Applied Respiratory Physiology, 2nd Edition, London: Butterworths (1977).Google Scholar

Copyright information

© Canadian Anesthesiologists 1981

Authors and Affiliations

  • H. R. Wexler
    • 2
  • Peter Lok
    • 1
  1. 1.Department of Respiratory TechnologyUniversity of Western Ontario, University HospitalLondonCanada
  2. 2.Department of AnaesthesiaUniversity HospitalCanada

Personalised recommendations