[A proper size of endotracheal tube for infant and young child--a retrospective study in Mackay Memorial Hospital].
BACKGROUND
There are more than 2000 pediatric patients receiving surgery in Mackay Memorial Hospital each year. Most of these surgery were performed under general anesthesia with endotracheal tube; therefore choosing an appropriate size of endotracheal tube becomes an important issue in our daily practice.


METHODS
Our principle is to choose an uncuffed Mallinckrodt endotracheal tube with a proper internal diameter (ID), ranging from 2.5 mm to 6.5 mm, which could be suitably and gently inserted into the trachea under full muscle relaxation. The tube would then be immediately removed and replaced with a smaller one if facing obvious resistance during intubation. After intubation, a leak test was applied to ascertain that there was no excessive gas leakage. We reviewed all anesthetic records of elective pediatric surgery in the recent 6 years, and the patients whose age above 8.5 years old and body weight (Wt) above 30 kg were excluded from this study. Using age (6476 cases) and Wt (6406 cases) as our parameters, we analyzed these data according to the distribution of each size of uncuffed endotracheal tube (UCETT) in different age and Wt intervals and compared them with the recommended Western reports.


RESULTS
Our results revealed that (1) the UCETT size increases as age or Wt increases; (2) considerable spread of UCETT sizes for different age and Wt intervals and basically represent as normal distribution; (3) for the case of even age equal or above 2 years old (up to 8 years old), the ID of the most frequently used UCETT can be memorized as (18 + age in years) divided by 4 or the outer circumference (OC) of the Mallinckrodt UCETT (in French unit, Fr) = 19 + age in years; and (4) Wt as a parameter for tube size selection was as powerful as age (94.76% vs. 94.65%).


CONCLUSIONS
From our results, we concluded that "whatever method of predicting tube size is used, tracheal tubes 0.5 mm larger and smaller should be available at the time of intubation so that the proper size can be chosen when the glottis is visualized."
D000367:Age Factors; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007442:Intubation, Intratracheal; D012189:Retrospective Studies