한국인의 폐활량(肺活量) 및 최대환기량(最大換氣量)에 관한 연구 : 특히, 정상치예측수식(正常値豫測數式)에 관하여
The vital capacity (VC) and the maximal breathing capacity (MBC) are widely used in evaluation of the pulmonary function, among various parameters of pulmonary function. Therefore, it is important to have a prediction formula with which one can compute the normal value for the subject and then compare with the measured value. In fact, these formulas have been derived for the American by Baldwin et al.(1948) and for the Japanese by Tatai (1958) and Tatai (1957). However, a formula for the Korean is not yet available in the literature and hence the formulas derived by Baldwin et al. (1948) for the american are applied to the Korean.
Although it has been indicated recently by Park (1964) that the Baldwin's formula for the prediction of VC may be applied to the Korean, no report on the applicability of the Baldwin's formula for MBC on the Korean is available. Hence, the author attemped to actually derive the formulas for the prediciton of both VC and MBC of the Korean.
Vc was measured in 10,129 healthy Koreans(5,306 male and 4,823 female) whose ages ranged from 7 to 60 years. Since the measurement of MBC is far more difficult than that of VC, it was measured in 1,062 healthy Koreans (500 males and 562 females)
whose ages ranged from 14 to 60 years.
A Collins vitaloment was used for the measurement of VC while a 9ι collins spirometer was used for MBC. Both VC and MBC were measured 3 times in a standing position and the highest value was used. For the measurement of MBC, the CO^^2 absorber was removed from the spirometer inorder to lower the resistance in the breathing system, and the subject was asked to breathe as fast deep as possible for 12 seconds. The investigator stood by the subject during the measurement to give a constant encouragement. All the measured values were subsequently converted to values at BTPS.
In deriving the formula for VC the following precedures were taken:
(1) Separate subjects by sex.
(2) Compute the average value of VC and the height for each age group of male and female.
(3) Compute the Smirnov's critical coefficient for each subject.
(4) Reject those values in which the above coofficient is greater than 2.5.
(5) Using the remainder of the measured values, derive the formula by the least square method.
Out of 10,129 subjects in whom VC were measured, 132 subjects(1.3%) were rejected because of high Smirnov's critical coefficient. Since VC is mainly determined by sex, age and height, the formula for VC was derived as a function of the age and height for male and female. Moreover, VC increased in proportion to the age until 20 years after which it decreased and hence separate formulas were derived for subjects below and above 20 years old.
The formulas for MBC were derived by a manner similar to those for VC. However, the Smirnov's critical coefficient was computed for each value of MBC and the body surface area (BSA), the formula was derived as a function of age and BSA. Moreover, formulas were also derived for the male and the female over 20 years old. Of 802 subjects over 20 years, 75 subjects(8.5%) were disregarded because of high Smirnov's coefficient.
The computation of Smirnov's critical coefficient (T^^N) was based on the following formula:
T^^N=｜X^^N-X^^N｜ / S^^N
where S^^N=Sampling variance for each age group.
X^^N=Mean value for each group.
The prediction formulas for VC (ml, BTPS) as derived in this investigation are as follows:
For male, below 20 years, VC=(7.15+0.82 x age(yrs)) x Height(cm)
above 20 years, VC=(29.43-0.186 x age(yrs)) x Height(cm)
For female, below 20 years, VC=(6.98+0.54 x age(yrs)) x Height(cm)
above 20 years, VC=(18.63-0.086 x age(yrs)) x Height(cm)
These formulas may be compared with those derived by Baldwin et al. for Americans over 20 year old:
For male, VC=(27.63-0.112 x age(yrs)) x Height(cm)
For female, VC=(21.78-0.101 x age(yrs)) x Height(cm)
By comparing these with the author's formulas, one can easily notice the differences between the Korean and the American. For instance, VC of young Korean male are similar to those of the American of the same age and height, but VC of old Korean male are lower than those of the American. For a man of 60 years sold and 165 cm in height, this difference in VC was 430ml which is equivalent to approximately 15%. In contrast, VC of the Korean female are uniformly lower than those of the American female over the entire range of age over 20 years. For a woman of 160cm in height, this difference was approximately 400ml which is equivalant to 12%. In this connection, it is also interesting to note that VC of the Japanese male(Tatai, 1958) are similar to those of the American while VC of the Japanese female (Tatai, 1957) are similar to those of the Korean.
The formulas for MBC (L/min, BTPS) of the Korean as derived in this investigation are as following:
For male, MBC=(89.14-0.594 x age(yrs)) x BSA(m**2)
For female, MBC=(66.69-0.477 x age(yrs)) x BSA(m**2)
These formulas may be compared with those of Baldwin et al.(1948) on the American:
For male, MBC=(86.5-0.522 x age(yrs)) x BSA(m**2)
For female, MBC=(71.3-0.474 x age(yrs)) x BSA(m**2)
A comparison of these formulas indicate that MBC of Korean males is similar to that of the American of the same age and BSA. However, even for the same age and BSA, MBC of the Korean female is lower than that of the American. This difference amounts to approximately 3 L/min when the BSA of subject is 1.6m**2. It may also be noted that MBC of the Japanese males is equivalant to that of the Korean men while MBC of the Japanese females is approximately 10% lower than that of the Korean females.
These results clearly indicate that both VC and MBC of the Korean can not be predicted on the basis of formulas by Baldwin et al., except for the MBC of the Korean male. Why there exists such a difference between the Korean and the American is by no means clear at this stage, but it is interesting to note that there were great differences in female than in male. Moreover, there were some similaritis in both VC and MBC between the Korean and the Japanese female. At any rate, the present investigation clearly reveals the Baldwin's formulas are not suitable to be applied to the Korean. except adult males.