Conclusion
It would appear from this small study that the “educated hand” and the anaesthetitist’s clinical judgment are really not too uneducated and that they more consistently produce safe arterial pCO2 levels than does the use of the Radford nomogram as originally described, and the Wright ventilation meter when used under standard everyday conditions of practice. The nomogram can be used to provide adequate ventilation if the sources of error are appreciated and allowances are made for these by increasing the values by at least 25 per cent in extrathoracic cases and by 100 per cent in those cases with open pneumothorax. It is unlikely that significant hypoventilation or hyperventilation will be produced in the average case if such additions to the nomogram are made. If endotracheal anaesthesia is used and Radford’s modified correction factor for this is applied, then it is likely, in extrathoracic cases at least, that the Radford nomogram will provide adequate ventilation under clinical conditions using everyday standard anaesthetic equipment. Because of the frequency of the sudden changes which can occur in the surgical procedure or in the anaesthetic state, both of which can rapidly change compliance, it is essential that the tidal volume be monitored frequently if adequate exchange is to be maintained throughout the operative procedure when using the nomogram with a mechanical ventilator. If the range of normal arterial pCO2 tensions is taken to be 35-45 mm of mercury, then the modified nomogram will usually provide these levels in most extrathoracic cases anaesthetized and ventilated under everyday conditions of anaesthetic practice.
Summary
The Radford nomogram and the Wright ventilation meter have been often recommended as a useful, reliable method of providing satisfactory ventilation during anaesthesia, with certain reservations. Previous studies have been reviewed. The use of the nomogram and meter under usual clinical conditions has been carried out and the adequacy of ventilation has been determined by measurement of arterial carbon dioxide tension. It was found that the muchmaligned “educated hand” was a more reliable means of maintaining arterial carbon dioxide tensions at safe levels than was the nomogram under these conditions. It is believed that in extrathoracic cases increasing the nomogram value by at least 25 per cent, and with an open pleura by 100 per cent, the nomogram will provide safe levels of arterial carbon dioxide during anaesthesia with controlled or artificial respiration.
Résumé
On a souvent recommandé le nomogramme de Radford et ľusage du ventimàtre de Wright comme méthode utile et fiable ďassurer une ventilation satisfaisante au cours de ľanesthésie, mais sous certaines réserves. Nous avons fouillé la littérature. Dans les conditions cliniques ordinaires, on a employé le nomogramme et le ventimàtre et ľon a vérifié si la ventilation était adéquate en mesurant la pression du CO2 artériel.
Les résultats révèlent que la main la plus malhabile demeure un moyen beaucoup plus fiable pour maintenir des tensions de CO2 artériel à des taux normaux que le nomogramme dans les mêmes conditions. Nous sommes ďopinion que, dans les cas extrathoraciques, il faudrait augmenter le nomogramme ďau moins 25 pour cent et, quand la plèvre est ouverte, de 100 pour cent, si ľon veut conserver des taux de CO2 artériel de tout repos au cours de ľanesthésie sous respiration contrôlée ou artificielle.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Evans, F. T. &Gray, C., Modern Trends in Anaesthesia. London: Butterworths, (1962).
Allen, G. D. &Morris, L. E. Central Nervous System Effects of Hyperventilation during Anaesthesia. Brit. J. Anaesth.34(5): 296–305 (1962).
Clutton-Brock, J. The Cerebral Effects of Overventilation. Brit. J. Anaesth.20(3): 111–113 (1957).
Sugioka, K. &Davis, D. A., Hyperventilation with Oxygen: A Possible Cause of Cerebral Hypoxia. Anesthesiology21(2): 135–141 (1960).
Woolmer, R. Ventilation during Anaesthesia. Anaesthesia15(1): 66–67 (1960).
Radford, E. P.;Ferris, B. G. Jr.; &Kriete, B. C., Clinical Use of a Nomogram to Estimate Proper Ventilation during Artificial Respiration. New Engl. J. Med.251 (22): 877–884 (1954).
Radford, E. P. Jr. Ventilation Standards for Use in Artificial Respiration. J. Appl. Physiol.7: 451–460 (1955).
Nunn, J. F. Ventilation Nomograms during Anaesthesia. Anaesthesia15(1): 65 (1960).
Campbell, E. J. M.;Nunn, J. F.; &Peckett, B. W. A Comparison of Artificial Ventilation and Spontaneous. Respiration with Particular Reference to Ventilation Blood Flow Relationships. Brit. J. Anaesth.30(4): 165–175 (1958).
Theye, R. A. &Fowler, W. S. Carbon Dioxide Balance during Thoracic Surgery. J. Appl. Physiol.14: 552–556 (1959).
Thornton, J. A. Physiological Dead Space: Changes) during General Anaesthesia. Anaesthesia25 (4): 381–393 (1960).
Nunn, J. F. &Hill, D. W. Respiratory Dead Space and Arterial to End Tidal Carbon Dioxide Tension Difference in Anaesthetized Man. J. Appl. Physiol.15: 383–389 (1962).
Woolmer, R. F. A Symposium on pH and Blood Gas Measurement: Methods and Interpretation, p. 81. London: J. & A. Churchill Ltd. (1959).
Nunn, J. F. &Ezi-Ashi, T. I. The Accuracy of the Respirometer and Ventigrator. Brit. J. Anaesth.24(7): 422–432 (1962).
Mushin, W. W.;Randell-Baker, L.; &Thompson, P. W. Automatic Ventilation of the Lungs, pp. 27–30. Springfield, Ill.: Charles C. Thorrjas (1959).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gain, E.A. The adequacy of the radford nomogram during anaesthesia. Can. Anaes. Soc. J. 10, 491–500 (1963). https://doi.org/10.1007/BF03002076
Issue Date:
DOI: https://doi.org/10.1007/BF03002076