Fast vital capacity is the volume of gas can be exhaled by maximal voluntary effort following fullest inspiration, expiration being as rapid as complete as possible ("forced"). Forced expiratory volume(FEV, qualified by time interval T : FEVT or timed vital capacity) is a measurement of a fast vital capacity related to be the time required for the maneuver.
Therefore, it is important to have a formula with one compute the normal value for the subject and compare with the measured value. Hence, present study was attempt to derive the formulas for prediction of forced expiratiry voliume(FEVT, ml) of the normal Korean children and adolescents.
Forced expiratory volume was measured in healthy Korean children and adolescents (556 male and 390 female) whose age range from 8 to 18 years. A 9 litter spirometer (Collins Inc.) was used for the measurement of FEV. The subject was trained on how to perform a fast vital capacity. Then, with nose clip in place, subject breathed
quietly through spirometer for a few breaths, then takes as deep a breath as possible, and then exhales all the gas within the lung as rapid as forcefully as possible (drum speed was 32 min/sec and standing position). Towards the end of the expiration the. subject was exhausted to continue the effort until no further gas was expired. During the measurement investigator stood by the subject to give a constant encouragement and measurement was repeat two or three times and the best one was subjected to analysis.
Two values of FEV were calculated the volume exhaled during the one-half and the first second(FEVT, ml) and the percentage of the total vital capacity exhaled du-ring the one-half, the first and the first two second (FEVT, %).
In addition to FEV, maximum mid-expiratory flow(MMF) was obtained from the forced expiratory spirogram and all the measured values were subsequently converted to values at BTPS.
The results are summerized as follows
1. The total vital capacity was increased linearly with ages until 17 in both sexes. The values of male and female at the age of 17 were 4369±470 and 3220±510ml, respectively.
2. The forced expiratory volume(FEVT, ml) was increased linearly with ages until 17 in both sexes. The FEVo.5 were 2643+367 ml in male and 2089±308 ml in female, and the FEV1.o were 3815±425 ml in male and 2897±373 ml in female at the age of 17.
3. The FEV. of male and female were 65.6±8. 1 and 64.4±10.1% in the age of 8, and this values were not related to the age in both sexes. FEV1.0 was about 90% in all ages and bofh sexes.
4. Correlation coefficients between MMF and FEV or FEV 0.5 (ml) were 0. 75 and 0.74 in male, and 0.83 and 0.84 in female subjects.
5. The prediction formula for forced expiratory volume (FEVT, ml, BTPS) was derived f om above results were as follows.
For male FEV0.5 = {3.55+ (0.71 x age)) x Ht (cm)
FEV1. o= (2.79+(1.13xage))XHt(cm) . For Female FEV= {3.98+ (0.53 X age) } x Ht (cm.) FEV1, o= {5.59+ (0.75 x age)} x Ht (cm.)
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