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Canadian Anaesthetists’ Society Journal

, Volume 32, Issue 3, pp 272–277 | Cite as

End-tidal carbon dioxide tension and temperature changes after coronary artery bypass surgery

  • François Donati
  • Jean-Guy Maille
  • Robert Blain
  • Marcel Boulanger
  • Philippe Sahab
Article

Abstract

Variations in end-tidal carbon dioxide partial pressure (PetCO2) and temperature were measured for six hours following coronary artery bypass surgery in twenty patients. In the recovery room, the patients were mechanically ventilated with a tidal volume of 12 ml·kg-1. Arterial blood gases were drawn every two hours, and the respiratory frequency was adjusted to maintain arterial carbon dioxide pressure (PaCO2) in the range of 30– 45 mmHg. Naso-pharyngeal temperature was recorded every 30 minutes, andPetCO2 was measured continuously. The mean difference between temperature-corrected arterial and end-tidal CO2 pressure measurements was 3.2 mmHg (SD = 2.8; r = 0.963). This difference did not vary with time, temperature or PCO2. The largest temperature increases (mean 1.7°C/hour) occurred at a mean of 253 minutes after the end of surgery. End-tidal PCO2 increased markedly as temperature rose, in spite of a coincident increase in ventilation and then decreased as temperature stabilized. Large increases in CO2 production, caused by the metabolic demands during rewarming, most likely account for these changes. It is concluded that end-tidal CO2 recordings are reliable, and can help in maintaining normocarbia during the short but unstable period associated with rewarming following cardiac surgery.

Key words

anaesthesia cardiovascular temperature body ventilation postoperative carbon dioxide tension 

Résumé

Chez vingt malades ayant subi des pontages aorto-coronariens, nous avons mesuré les variations des pressions de gaz carbonique enfin d’expiration (PetCO2) et les changements de temperature au cours des six premieres heures post-operatoires. Ces malades étaient ventileés mécaniquement et leur volume courant était de 12 ml·kg-1. Les gaz du sang artériel étaient analysés aux deux heures et la fréquence respiratoire ajustée de façon à maintenir un PaCO2 entre 30 et 45 mmHg. La temperature naso-pharyngée était notée aux trente minutes et laPetCO2 mesurée de façon continue. Lorsque la PaCO2 est corrigée en fonction de la température, la différence moyenne entre cette PaCO2 et laPetCO2 est de 3.2 mmHg (SD = 2.8; r = 0.963). Cette différence n’est pas influencée par le temps, la température ni les valeurs de PCO2 . Vers la quatrième heure après la fin de la chirurgie, la température corporelle s’élève rapidement (en moyenne de 1.7° Clheure). LaPetCO2 s’accroît de façon marquée au moment de l’lévation de température, malgré une augmentation concomitante de la ventilation; puis laPETCO2 diminue lorsque la température corporelle se stabilise. Ces changements semblent être dus à une augmentation importante de la production de CO2, suite a des demandes métaboliques accrues au cours du réchauffement. Done, l’enregistrement continu du CO2 en fin d’expiration (PetCO2) est une méthode fiable qui peut aider à maintenir une normocarbie au cours de la période courte mais instable qui accompagne le réchauffement.

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Copyright information

© Canadian Anesthesiologists 1985

Authors and Affiliations

  • François Donati
    • 1
  • Jean-Guy Maille
    • 1
  • Robert Blain
    • 1
  • Marcel Boulanger
    • 1
  • Philippe Sahab
    • 1
  1. 1.Department of AnaesthesiaMontreal Heart InstituteMontrealCanada

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