ABSTRACT
This study was carried out to assess the occurrence of pulmonary emphysema early among smokers [symptomatizing and non symptomatizing] by hellical chest CT and relating this finding to pulmonary function. In order to achieve this purpose 55 smokers [25 asymptomatic and 30 symptomatic] and 10 apparently healthy non smokers control subjects were in vestigated through: I. Full detailed medical history with particular attention to smoking habits. II. Full clinical examination comprising both general and local chest examination. Ill. Plain chest X-ray, posterio-anterior [P A] and lateral views. IV. Pulmonary function tests, using computerized sensor medics 2450. [1] flow volume loop data, before and 20 minutes after inhalation of 4 puffs [400 micro g] of salbutamol using MDI to exclude asthmatic. [2] functional residual capacity [FRC] helium equilibration test. [3] pulmonary diffusing capacity [DL[co]] and pulmonary diffusing coefficient [DL[co]/VA] [alveolar volume VA]. V. High resolution chest CT [HRCT] .Analysis of the computed tomograms was performed visually according to Goddard et al. [5]. VI. Subjects proved to have other concomitant disease or known COPD were excluded from this study in asymptomatic smokers 16 out of 25 [64%] have emphysema by HRCT. Plain chest x-ray of those 16 smokers having emphysema by HRCT were normal in all [100%] and 9 of them [56.3%] have normal pulmonary functions in symptomatic smokers 27 out of 30 [90%] were having emphysema by HRCT. Twenty six percent of those symptomatic smokers having emphysema by HRCT showed normal plain chest x-ray. On comparing the validity of plain x-ray versus HRCT in the diagnosis of pulmonary emphysema plain x-ray has 35.5% sensitivity, 95.4% specificity, 95.0% predicted value positive, 46.7 predicted value negative and 61.5% accuracy. Correlation between pulmonary functions and emphysema score by HRCT in both asymptomatic and symptomatic smokers showed that there was only significant negative correlation between emphysema score and DL[co]/VA in asymptomatic smokers [P < 0.05] but in symptomatic smokers there is highly significant negative correlation with all parameters of pulmonary functions except total lung capacity [TLC]. residual volume [RV] RV/TLC and FRC [I] HRCT is the best mean for early detection of pulmonary emphysematous changes among smokers as it is better in this respect than pulmonary functions. [2] Plain chest X-ray is less sensitive than pulmonary functions in early detection of pulmonary emphysema. [3] DL[co]/V A is the most sensitive pulmonary function test to be affected early in pulmonary emphysema