RELATIONSHIP BETWEEN END-TIDAL AND ARTERIAL CARBON-DIOXIDE WITH LARYNGEAL MASK AIRWAYS AND ENDOTRACHEAL-TUBES IN CHILDREN

The laryngeal mask airway (LMA) is a useful tool for securing the airw ay in adults and children and may be substituted for an endotracheal t ube (ETT) in selected patients undergoing general anesthesia. The corr elation between end-tidal and arterial carbon dioxide during controlle d ventilation via LMA has not been reported in a within-patient design in pediatric patients. After induction of general anesthesia, 22 chil dren had a LMA placed and mechanical ventilation initiated. After reac hing steady-state end-tidal carbon dioxide (PETCO(2)), an arterial blo od sample was obtained and the partial pressure of carbon dioxide (Pac o(2)) was measured. The LMA was then removed, the trachea was intubate d, and identical ventilatory variables were resumed. After a stable PE TCO(2) was reestablished (minimum 5 min), a second Paco(2) was measure d and the PETCO(2) recorded. The mean PETCO(2), and Paco(2) obtained d uring ventilation via the LMA were 37.7 +/- 3.31 and 41.9 +/- 9.09, re spectively. The mean PETCO(2) and Paco(2) obtained during ventilation via the ETT were 35.2 +/- 2.86 and 39.2 +/- 5.25, respectively. Analys is of differences between Pace, and PETCO(2), revealed a bias +/- prec ision of 4.0 +/- 3.42 and 4.2 +/- 3.66 with ventilation via ETT and LM A, respectively. The root mean square error was 0.85 for the ETT and 0 .89 for the LMA. Our results indicate that in infants and children wei ghing more than 10 kg who are mechanically ventilated via the LMA PETC O(2) is as accurate an indicator of Paco(2) as when ventilated via ETT .