Distal oesophageal pH measurement in children during general anaesthesia using the laryngeal mask airway (TM), tracheal tube and face mask

Background: Distal oesophageal pH was measured during controlled ventilatio n in children with the laryngeal mask airway (LMA(TM)), tracheal tube (TT) and face mask (FM). Methods: Fifty-six children scheduled for inguinal surgery with a standardi zed general anaesthetic technique were randomly allocated to receive LMA (n = 21), TT (n = 18) or FM (n = 19). A 14 Fr pH probe was placed into the di stal oesophagus and pH values were measured over 1 min at 2-min intervals d uring the first 20 min of anaesthesia. Results: The median values of pH were 4.4 (3.5-5.5), 4.2 (3.3-4.9), 4.1 (3. 2-5.1), 4.1 (3.3-5.0), 4.0 (3.3-4.9), 4.0 (3.4-5.1); 4.2 (3.3-5.1), 4.2 (3. 6-5.0), 4.2 (3.5-5.0), 4.2 (3.5-5.2), 4.2 (3.5-5.0), 4.1 (3.5-5.0) and 4.2 (3.6-5.0), 4.2 (3.8-5.8), 4.1 (2.8-5.2), 4.2 (3.3-5.1), 4.2 (3.4-5.1), 4.3 (3.4-5.1) for LMA, TT and FM groups, respectively. Conclusions: There was no difference in the median pH values, within and be tween the groups (P > 0.05). We conclude that there is no difference in gas tro-oesophageal reflux, when using a LMA, TT or FM during controlled ventil ation in anaesthetized children.