Normal Predicted Value of Airway Resistance by Flow Interrupter Technique in Korean Kindergarden Children

Son, Byong Kwan; Lim, Dae Hyun; Kim, Jeong Hee

Abstract

PURPOSE
To get the normal predicted value of airway resistance in Korean kindergarten children by using a flow interrupter technique which is simple and easy enough to be applicable even to young children.
METHODS
Two hundred and fifty children (male 126, female 124) were enrolled from two kinderdargen in Inchon. Excluded children were out of normal range of Korean growth standard, without any history and/or on-going symptom and sign of airway diseases. One medical doctor, well trained to the Microlab 4000 (Micromedical Co., England, educated those children in advance and carried out all the procedure. the Rint (airway resistance by interrupter technique) was checked 5 times. After the exclusion of both the highest and the lowest values, we got the average of remaining 3 values as the Rint (in both inspiratory and expiratory phases). The mean, standard deviation, regression equation, correlation coefficient for each group of age, height, weight, and chest circumference in both sex were investigated.
RESULTS
1) Age ranged from 3 to 5 years. 3-year-old boys' Rint were 1.89+/-0.76 kPa.l(-1).s and 1.78+/-0.71 kPa.l(-1).s in inspiratory and expiratory phase, respectively. Those for girls were 1.94+/-0.73 kPa.l(-1).s and 1.72+/-0.73 kPa.l(-1).s. The Rint was decreased as the children got older. 2) Height ranged from 91 to 120 cm. Rint of boys from 96 to 100 cm in height were 1.86+/-0.70 kPa.l(-1).s and 1.54+/-0.49 kPa.l(-1).s in inspiratory and expiratory phase, respectively. Those for girls were 1.68+/-0.72 kPa.l(-1).s and 1.71+/-0.77 kPa.l(-1).s. The Rint was decreased as the children got taller. 3) Weight ranged from 13 to 27 kg. Rint of boys from 13 to 15 kg in weight were 1.49+/-0.76 kPa.l(-1).s and 1.55+/-1.00 kPa.l(-1).s in inspiratory and expiratory phase, respectively. Those for girls were 1.78+/-0.83 kPa.l(-1).s and 1.82+/-0.76 kPa.l(-1).s. The Rint was decreased as the children got heavier. 4) Chest circumference ranged from 46 to 70 cm. Rint of boys from 51 to 55 cm in chest circumference were 1.69+/-0.84 kPa.l(-1).s and 1.52+/-0.74 kPa.l(-1).s in inspiratory and expiratory phase, respectively. Those for girls were 1.63+/-0.81 kPa.l(-1).s and 1.52+/-0.74 kPa.l(-1).s. The Rint was decreased as the children's chest circumference was increased. 5) Regression equations and correlation coefficients were calculated by each group of age, height, weight, and chest circumference for both boys and girls and in both inspiratory and expiratory phases. The correlation coefficient with age was around 0.5, which was the highest among them.
CONCLUSION
The normal predicted value of airway resistance by flow interrupter technique was measured. It can be used for evaluating lung condition, progression of lung disease, and the effectiveness of drugs in lung disease.