END-TIDAL CARBON-DIOXIDE MEASUREMENT IN INFANTS AND CHILDREN DURING AND AFTER GENERAL-ANESTHESIA

We have examined the reliability of end-tidal carbon dioxide (PETCO(2) ) monitoring as an estimate of arterial carbon dioxide tension (PaCO2) in spontaneously breathing infants and children. Forty patients were studied in the post-anaesthetic care unit; 20 < 12 kg and 20 T 12 kg. The PETCO(2) was sampled via a 5 cm 16 gauge catheter taped below an e xternal naris and this measurement war compared with the PaCO2 of a sa mple drawn from an indwelling arterial line. Twenty additional patient s were studied during inhalational anaesthesia. The PETCO(2) war. meas ured both from the proximal end of the elbow connector and from a 5 cm cannula inserted through the elbow. An arterial blood gar sample war obtained simultaneously. The arterial to end-tidal (Pa-ET) differences were compared between the two sites. Patients studied in the post-ana esthetic care unit showed good correlation between PETCO(2) and PaCO2 regardless of weight: Pa-ETCO(2) of -0.6 +/- 3.6 (<12 kg) and -1.1 +/- 2.8 mmHg (greater than or equal to 12 kg). Patients studied during ma sk anaesthesia showed better correlation between PETCO(2) and PaCO2 wh en PETCO(2) was sampled from the cannula: Pa-ETCO(2) of 3.5 +/- 4.8 mm Hg (cannula), 8.6 +/- 4.5 (elbow) (P < 0.05). These results suggest th at end-tidal CO2 monitoring is a useful and reliable method for assess ing adequacy of ventilation in spontaneously breathing children weighi ng between 5.2 and 35 kg.