Abstract
To determine the accuracy of end-tidal PCO2 (PETCO2) measurements analyzed with a sidestream capnometer in infants and children whose lungs were ventilated with a Sechrist infant ventilator and an Ayre’s t-piece, we compared PETCO2 measurements obtained from the proximal (PeiCO2-p) and distal (PETCO2-d) ends of the tracheal tube to arterial PCO2 (PaCO2) in 37 healthy infants and children between 1.3 and 24.5 kg. Both PETCO2-p and PETCO2-d accurately approximated PaCO2, however, the mean (± SD) arterial to end-tidal PCO2 difference (Δ(a-ET)PCO2) was significantly greater with proximal (1.27 ± 1.54 mmHg) than with distal sampling (0.64 ± 1.64 mmHg) (P < 0.01). In the subgroup of patients who weighed < 12 kg, the Δ(a-ET)PCO2 using proximal gas sampling (1.94 ± 1.29 mmHg) was also significantly greater than it was using distal sampling (0.74 ± 1.31 mmHg) (P < 0.001). We conclude that although statistically different, both proximal and distal estimates of PETCO2 provide acceptable estimates of PaCO2 in healthy infants and children who are ventilated with a Sechrist infant ventilator and an Ayre’s t-piece system.
Résumé
Chez 37 enfants en bonne santé pesant de 1,3 à 24,5 kg, nous avons mesuré la PCO2 en fin d’expiration (PetCO2) avec un capnomètre à infrarouge qui aspirait soit au bout distal (PETCO2-d) soit au bout proximal (PETCO2-p) d’un tube endotrachéal branché sur un respirateur Sechrist ou sur une pièce en T de type Ayre. La PETCO2-p et la PETCO2-d représentaient toutes deux, un estimé adéquat de la PCO2 artérielle. Toutefois la différence (moyenne ± écart-type) entre la PCO2 artérielle et enfin d’expiration (Δ(a-ET)PCO2) était plus grande pour le site d’aspiration proximal que pour le site distal: 1,27 ± 1,54 mmHg vs 0,64 ± 1,64 mmHg, P < 0,01. Pour les patients de moins de 12 kg, ce gradient affichait le même comportement avec 1,94 ± 1,29 mmHg au site proximal et 0,74 ± 1,31 mmHg au site distal, P < 0,001. Malgré une certaine différence, les deux sites d’aspiration permettent donc d’obtenir une PetCO2 estimant adéquatement la PaCO2 d’enfants en bonne santé, ventilés avec une pièce en T ou un respirateur Sechrist.
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Hillier, S.C., Badgwell, J.M., McLeod, M.E. et al. Accuracy of end-tidal PCO2 measurements using a sidestream capnometer in infants and children ventilated with the Sechrist infant ventilator. Can J Anaesth 37, 318–321 (1990). https://doi.org/10.1007/BF03005582
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DOI: https://doi.org/10.1007/BF03005582