Abstract
A randomized, prospective study was performed to evaluate the accuracy of a new transcutaneous carbon dioxide (CO2) monitor (Fastrac™) during general anaesthesia. Twenty-two adult patients undergoing elective surgery were subjected to three different levels of minute ventilation by varying their respiratory rates in a randomized cross-over design. Simultaneous measurements of transcutaneous CO2 (PrcCO2) and arterial CO2 (PaCO2) were obtained at three levels of minute ventilation (low, medium and high). End-tidal CO2 (PetCO2) values were also recorded from a mass spectrometer (SARA™) at each time period. A total of 66 data sets with PaCO2 ranging from 28–62 mmHg were analyzed. The PrcCO2 values demonstrated a high degree of correlation with PaCO2 over the range of minute ventilation (y = 0.904x + 6.36, r = 0.92, P < 0.001). ThePetCO2 measurement also demonstrated a generally good correlation with PaCO2 (y = 0.62x + 9.21, r = 0.89, and P < 0.01). However, thePetCO2-PaCO2 gradients (mean 7.0 ±3.1 mmHg) were greater than the PtcCO2-PaCO2 gradients (mean 2.3 ±2.4 mmHg) at all three levels of minute ventilation (P < 0.05). These differences were greatest when PaCO2 was in the high range (48–60 mmHg). We conclude that the new Fastrac™ CO2 monitor is accurate for monitoring carbon dioxide levels during general anaesthesia. The new transcutaneous devices provide an effective method for non-invasive monitoring of CO2 in situations where continuous, precise control of CO2 levels is desired.
Résumé
Une étude prospective randomisée fut entreprise afin d’évaluer durant l’anesthésie générale un nouveau moniteur transcutané de CO2 (Fastrac™). Vingt-deux patients adultes subissant une chirurgie élective ont subi trois différents niveaux de ventilation minute en variant la fréquence d’une façon randomisée avec entrecroisage. Les mesures simultanées de la CO2 transcutanée (PtcCO2) et la CO2 artérielle (PaCO2) furent obtenues à trois niveaux de ventilation minute (bas, moyen et élevé). Les valeurs de la CO2 enfin d’expiration (PetCO2) furent aussi enregistrées par un spectromètre de masse (SARA™) à chaque période. Un total de 66 ensembles de données avec des PaCO2 variant de 28–62 mmHg furent analysées. Les valeurs de PrcCO2 ont démontré un haut degré de corrélation avec la PaCO2 pour ces valeurs de ventilation minute (y = 0,904x + 6,36, r = 0,92, P < 0,001). Les mesures de laPetCO2 ont aussi démontré une bonne corrélation avec la PaCO2 (y = 0,62x + 9,21, r = 0,89, et P < 0,01). Cependant, les gradients dePetCO2-PaCO2 (moyenne 7,0 ±3,1 mmHg) furent plus grands que les gradients de PrcCO2-PaCO2 (moyenne 2,3 ±2,4 mmHg) aux trois valeurs de ventilation minute étudiées (P < 0,05). Ces différences étaient plus élevées quand la PaCO2 était maintenue à des niveaux élevés (48–60 mmHg). On conclut que le nouveau moniteur de CO2 Fastrac™ est précis pour la surveillance du niveau du CO2 durant l’anesthésie générale. Ces nouveaux appareils transcutanés fournissent une méthode efficace pour la surveillance non-invasive de la CO2 dans des situations où un contrôle continu et précis du niveau de CO2 est désiré.
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Supported in part by a research grant from Johnson and Johnson (Medical Products) Inc.
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Reid, C.W., Martineau, R.J., Miller, D.R. et al. A comparison of transcutaneous, end-tidal and arterial measurements of carbon dioxide during general anaesthesia. Can J Anaesth 39, 31–36 (1992). https://doi.org/10.1007/BF03008669
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DOI: https://doi.org/10.1007/BF03008669