F. Rafi ( Department of Physiology, University of Karachi, Karachi-32. )
M. Bano ( Department of Physiology, University of Karachi, Karachi-32. )
A.H. Khan ( National Institute of Cardiovascular Diseases, Karachi-35. )
Pulmonary function was assessed in apparently healthy Pakistani, subjects according to age, sex, height, weight and body surface area. The observed values were less than those predicted for healthy Americans (Baldwin, et al. 1948). (JPMA 32:-.1982).
Normal physiological parameters are available in U.S.A. and in Eastern European countries countries (Bucherl 1955; Comroe et al. 1963; David et al. 1971) but no such studies are available in Pakistan. Minor abnormalities in pulmonary functions in patients with cardiorespiratory diseases cannot be detected in the absence of comparable data in healthy subjects.
In the present study, pulmonary function tests were done in healthy Pakistani individuals and compared with those reported by Baldwin et al. (1948) in healthy Americans.
Material and Methods
A hundred subjects (50 males and 50 females) of different age groups were selected according to their socio-economic status, occupation and place of origin.
The subjects were examined thoroughly to exclude cardiopulmonary disorders. The respiratory manoeuvrcs were explained to them and tests were performed at room temperature and in sitting positin.
13.5 liter C’lline respirometer (closed circuit spirometery) was filled with oxygen. The subject Pakistani Population was asked to breath normally for I to 2 minutes, and then resume quiet breathing after a maximal inspiration and expiration. From this tracing, respiratory rate, tidal volume, minute ventilation (Respiratory rate X Tidal Volume) inspiratory capacity, expiratory reserve volume and vital capacity were calculated (Fig. 1) To calcuate the percentage of forced expiratory volume in one second and maximum breathing capacity subject was asked to breathe normally for a minute then inhale maximally and then exhale rapidly arid deeply followed by resumption of quiet breathing (Fig. I) For both these pulmonary functions kymograph was set at a fast speed (1920 mm/min).The subject was asked to breathe as rapidly and as deeply as possible for 10-15 seconds and the readings were converted to one minute (Fig. I).
The gas volume recorded by the respirometer was corrected by a factor (BTPS) because the subject exhales the gas at 37C while the volume recorded on the spirograme was at room temperature. Factor for any given room temperature for correction of the measured volume to body temperature embient pressure and saturated with water vapour is called BTPS.
The higher correlation depends on size, area of lungs, expansibility of the chest, strength of muscles, excercise, hormonal effect, and life patterns. House wives and sedentary people show less value due to less physical exertion and working capacity. Predicted values for American population (Table VI) are higher than those of Pakistani population reported here which may be because Of environmental, conditious, economic, occupational and nutritional effects as well as geographical variations and psycho-social problems. Variations and errors in the present results may be due to the fact that the subject either fails to cooperate fully because of nonrespiratory factors like seif-conciousness, communication barriers, or anxiety because of suffocation due to the mouth piece used by the subject.
1. Baldwin, E. Def, Cournand, A. and Richards, D.W. j. (1948) Pulmonary insufficiency. I. Physiological classification, clinical methods of analysis, standard values in normal subjects. Medicine, 27:243.
2. Bates, D.V. Ct al. Respiratory function in disease; an introduction to the integrated study of the lung. 2nd ed. Philadelphia, Saunders 1971.
3. Bucherl, E.S. (1955) Thorax Chi urgie, 3:211. Ref. quoted in Book Methods in Pülmona y Physiology.
4. Comroe, J.H., Forster, R.E., Dubois, A.B., Briscoe, W.A. and Cariren, E. The lung; clinical physiology and pulmonary function tests. 2nd ed. Chicago, Year Book, 1962.