[The proper size of bronchial tube for pediatric differential lung ventilation using laryngeal mask airway].

BACKGROUND

Since the double lumen tube (DLT) for pediatric use is not commercially available, we have developed the method of differential lung ventilation using the laryngeal mask airway (LMA) and the cuffed-bronchial tube (BT) made with two conventional cuffed-tracheal tubes (Intermediate, Mallinckrodt).

METHODS

The proper inner diameters (IDs) of the BT were determined with the following condition; the inner cross-sectional area of BT is less than the outer cross-section area of BT in the trachea, or equal to it. The proper BT lengths were derived from the equation; the distance from LMA to swivel connecter + tracheal distance + cuff portion length of BT tip in main bronchus +3.5 cm.

RESULTS

The proper IDs of BT are 2 size smaller than those of proposed tracheal tube at the age of 5 yr or below, and 3 size smaller (max ID = 5.0 mm) at the ages over 6 yr.

CONCLUSIONS

Our method using the BT' (ID 3 mm, length 29 cm) with LMA size 2 could be applied to the patient aged less than 2 yr, weighing over 10 kg, and the non-cuffed BT (ID 2.5 mm, length 27.5 mm) through LMA size 1.5 could be used to those weighing over 5 kg.