Journal of Clinical Monitoring

, Volume 3, Issue 2, pp 73–79 | Cite as

End-tidal carbon dioxide as a measure of arterial carbon dioxide during intermittent mandatory ventilation

  • Matthew B. Weinger
  • John E. Brimm
Original Articles


To determine if end-tidal carbon dioxide tension (PetCO2) is a clinically reliable indicator of arterial carbon dioxide tension (PaCO2) under conditions of heterogeneous tidal volumes and ventilation-perfusion inequality, we examined the expiratory gases of 25 postcardiotomy patients being weaned from ventilator support with intermittent mandatory ventilation. Using a computerized system that automatically sampled airway flow, pressure, and expired carbon dioxide tension, we were able to distinguish spontaneous ventilatory efforts from mechanical ventilatory efforts. ThePetCO2 values varied widely from breath to breath, and the arterial to end-tidal carbon dioxide tension gradient was appreciably altered during the course of several hours. About two-thirds of the time, thePetCO2 of spontaneous breaths was greater than that of ventilator breaths during the same 70-second sample period. The most accurate indicator of PaCO2 was the maximalPetCO2 value in each sample period, the correlation coefficient being 0.768 (P < 0.001) and the arterial to end-tidal gradient being 4.24 ± 4.42 mm Hg (P < 0.01 compared with all other measures). When all values from an 8-minute period were averaged, stability was significantly improved without sacrificing accuracy. We conclude that monitoring the maximalPetCO2, independent of breathing pattern, provides a clinically useful indicator of PaCO2 in postcardiotomy patients receiving intermittent mandatory ventilation.

Key words

Carbon dioxide: tension Ventilation: artificial intermittent mandatory ventilation Surgery: cardiac 


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  1. 1.
    Burton GW. The value of CO2 monitoring during anesthesia. Anaesthesia 1966;21:173–183PubMedCrossRefGoogle Scholar
  2. 2.
    Hatle L, Rokseth R. The arterial to end-expiratory CO2 tension gradient in acute pulmonary embolism and other cardiopulmonary diseases. Chest 1974;66:353–357CrossRefGoogle Scholar
  3. 3.
    Poppius H. Arterial to end-tidal CO2 differences in respiratory disease. Scand J Respir Dis 1975;56:254–262PubMedGoogle Scholar
  4. 4.
    Whitesell R, Asiddao C, Gollman D, Jablonsk J. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–512PubMedCrossRefGoogle Scholar
  5. 5.
    Perrin G, Perrot D, Holzapfel L, Robert D. Simultaneous variations of PaCO2 and PACO2 in assisted ventilation. Br J Anaesth 1983;55:525–530PubMedCrossRefGoogle Scholar
  6. 6.
    Kinsella SM. Assessment of the Hewlett-Packard HP47210A capnometer. Br J Anaesth 1985;57:919–923PubMedCrossRefGoogle Scholar
  7. 7.
    Brimm JE, Bienzo RK, Knight MA, Peters RM. Breathby-breath end-tidal CO2 analysis for patients on IMV. In Prakash O, ed. Computers in critical care and pulmonary medicine. New York: Plenum, 1982:195–200Google Scholar
  8. 8.
    Nie NH, Hull CH, Jenkins JG, et al. Statistical package for the social sciences (SPSS). 2nd ed. New York: McGraw-Hill, 1975Google Scholar
  9. 9.
    Snedecor GW, Cochran WG. Statistical methods. 7th ed. Ames: Iowa State University, 1980:185–188Google Scholar
  10. 10.
    Feeley TW, Hedley-Whyte J. Weaning from controlled ventilation and supplemental oxygen. N Engl J Med 1975;292:903–906PubMedGoogle Scholar
  11. 11.
    Burton GW. Measurement of inspired and expired O2 and CO2. Br J Anaesth 1969;41:723–730PubMedCrossRefGoogle Scholar
  12. 12.
    Gothard JW, Busst CM, Brantwaite MA, et al. Applications of respiratory mass spectrometry to intensive care. Anaesthesia 1980;35:890–895PubMedCrossRefGoogle Scholar
  13. 13.
    Riker JB, Haberman B. Expired gas monitoring by mass spectrometry in a respiratory ICU. Crit Care Med 1976;4:223–229PubMedCrossRefGoogle Scholar
  14. 14.
    Potter WA. Mass spectrometry for innovative techniques of respiratory care, ventilator weaning, and differential ventilation in an ICU. Crit Care Med 1976;4:235–238PubMedCrossRefGoogle Scholar
  15. 15.
    Capan LM, Ramanathan S, Sinha K, Turndorf H. Arterial to end-tidal C02 gradients during spontaneous breathing, intermittent positive-pressure ventilation, and jet ventilation. Crit Care Med 1985;13:810–813PubMedCrossRefGoogle Scholar
  16. 16.
    Collier CR, Affekdt JE, Farr AF. Continuous rapid infrared C02 analysis. J Clin Lab Med 1976;45:526–539Google Scholar
  17. 17.
    Evans JM, Hogg MJ, Rosen M. Correlation of alveolar PCO2 estimated by infrared analysis and arterial PCO2 in the human neonate and the rabbit. Br J Anaesth 1977;49:761–764PubMedCrossRefGoogle Scholar
  18. 18.
    Briscoe WA, Firster RE, Comroe JH. Alveolar ventilation at very low tidal volumes. J Appl Physiol 1954;7:27–30PubMedGoogle Scholar
  19. 19.
    Dubois AB, Britt AG, Fenn WO. Alveolar C02 during the respiratory cycle. J Appl Physiol 1952;4:535–548PubMedGoogle Scholar
  20. 20.
    Jones NL, Robertson DG, Kane JW. Difference between end-tidal and arterial PCO2 during exercise. J Appl Physiol 1979;47:954–960PubMedGoogle Scholar
  21. 21.
    Smalhout B, Kalenda Z. An atlas of capnography. Vol. 1. 2nd ed. The Netherlands: Kerkebosch-Zeist, 1981Google Scholar
  22. 22.
    Lewis G, Ponte J, Purves MJ. Fluctuation of PaCO2 with the same period as respiration in the cat. J Physiol (Lend) 1980;298:1–11Google Scholar
  23. 23.
    Raemer DB, Francis D, Philip JH, Gabel RA. Variation in PCO2 between arterial blood and peak expired gas during anesthesia. Anesth Analg 1983;62:1065–1069PubMedCrossRefGoogle Scholar

Copyright information

© Little, Brown and Company, Inc. 1987

Authors and Affiliations

  • Matthew B. Weinger
    • 1
  • John E. Brimm
    • 2
    • 3
  1. 1.Dept of Anesthesiology, V-125Veterans Administration Medical CenterSan Diego
  2. 2.Surgery, Division of Cardiothoracic SurgeryUniversity of California Medical CenterSan DiegoCA
  3. 3.Emtek Health Care SystemsTempe

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