Normal Sudanese Spirometeric Values for Police Men

Background Spirometric values for police ocers in the police hospital, Khartoum, Sudan were observed to show higher values than predicted. 1 Reference values are important for diagnosis of asthma and chronic bronchitis Methods For deriving a new reference value for adult police men, a cross- sectional study was performed on 161 adult male police ocers, aged 20–50 years in (June- December 2012) in Khartoum state in different police units. Data were obtained through a questionnaire, pulmonary function testing and taking anthropometric measurements, forced vital capacity (FVC), forced expiratory volume in rst second (FEV1) and peak expiratory ow rate (PEFR) were measured using a microplus spirometer and a peak ow meter. Lung function values and anthropometric measurements were correlated and regression equations were derived

used a small sample and included only two areas of Sudan. 2 The study found that the Sudanese values were lower than the international ones, with differences between inhabitants of different areas. 3 A pilot study in Gezira (central Sudan) in 1998 gave similar indicators and con rmed the feasibility of performing a large national study to derive the normal spirometric values for Sudanese. 4 The last study to obtain normal spirometric values, in 2002-2005, included data from all areas of Sudan. 1 Reference values for health measures can be subject-based using baseline values from the same individual obtained when he/she in a de ned state of health or population-based using data obtained from a group of well-de ned reference individuals. In the case of respiratory parameters, prediction equations obtained from a reference population provide a baseline for evaluating the pulmonary function of a subject, based usually on the person's standing height, age and sex. 5 Lung function in relation to age and height has been studied extensively in Caucasians, [6][7][8][9] in whom these indices showed correlations with forced vital capacity (FVC), forced expiratory volume in 1 ( rst) second (FEV1), FEVI/FVC ratio (FEV,%), and forced expiratory ow (FEF). Ethnic differences in lung function have also been reported by many authors [10][11][12][13][14][15] , FVC and FEV1 have been shown to be lower in African blacks than in whites, while Indians and Chinese have intermediate FVC and FEV1 values. Lung function is greatly in uenced by age, gender, anthropometry and ethnicity [16][17][18][19] . Lung volumes, especially vital capacity, increased with height and lean body mass, but decreased with obesity. For the same weight and height, spirometric measurements were usually higher in males compared with females. Almost all equations for prediction of lung function in various populations include these parameters. 16,20,21 The results of Mälkiä et al showed signi cant associations between Spirometric values and intensities of physical activity at work and during leisure time in asthmatic men. 19 Although healthier subjects may select more physically demanding activities, it is an equally possible hypothesis that physical activity may improve respiratory function in subjects with and without bronchial asthma. The study showed that swimmers have superior FEV1 independent of stature and age in comparison with both land-based athletes and sedentary controls. 23 Physical activity is associated with a slower decline in pulmonary function and with lower mortality, and thus, middle-aged and older people should be encouraged to enjoy exercise. 24 Spirometric values for police o cers has been observed to be higher than the Sudanese predicted values.

2-1-Study design
This was cross-sectional study performed over the period June-December 2012 in Khartoum state, Sudan.

2-2-Subjects
A total of 161 adult male police o cer aged 20-50 years old were included. The sample size was calculated using a con dence level of 95%, precision level ±8%, P (maximum variability) = 0.5 and estimated population of 9000.
Adult male police subjects were chosen from different police units: Police security, faculty of Police and Police of protection of establishments. Ethical clearance for the study was issued by the National Ribat University.
Adult police male subjects were considered "normal" if they had never smoked tobacco; reported no history of symptoms of respiratory diseases; had normal cardiopulmonary signs on clinical examination; had no history of occupational exposure to dust; and were willing and able to cooperate. 25 Adult police male subjects were excluded if they did not satisfy the inclusion criteria; or if they did not perform the respiratory tests correctly.

2-3-Data collection
The questionnaire was lled by all subjects. The questionnaire included: personal data (age, height and weight); habits (smoking, sports) and personal health condition.
A stadiometer was used to measure the standing height of the adult police male subject in centimeters. A sensitive balance was used to measure the body weight in kilograms. A pocket spirometer (MicroPlus, Micro Medical) was used to measure FVC, FEV1. Peak ow meter was used to measure PEFR. Use of the spirometer was demonstrated to each subject. After maximal inspiration, the subject blew forcibly and continuously into the mouthpiece of the spirometerfor at least six second and the highest measurement of three trials was taken as the most representative of the subject's ability. FVC, FEV1, and PERF were recorded. Subjects were excluded if they failed to inspire before breathing out, failed to exhale due to inability to relax or leaked the air by expiring before holding the mouthpiece or not holding their lips tightly around the mouthpiece.
2-4-Data analysis: -Partial correlation test was used. Student t-test and analysis of variance were used to test the signi cance of differences (P ≤ 0.05). Multiple regression analysis was used to derive regression equations using SPSS, version 14 computer programme 2-5-Ethical considerations: Ethical clearance will be approved from the ethical committee at The National Ribat University -A written consent will be taken from all the participants in the study. Code numbers will be used for the participants that are included in the study.
Pulmonary function tests: The pulmonary function tests were carried out using portable spirometer. The apparatus provides a detailed analysis of predicted and derived values. After taking informed written consent from each subject, a detailed history was recorded to rule out the exclusion criteria.
Anthropometric measurements like height and weight were taken for these subjects.
The pulmonary function tests were repeated three times for each subject each time and the best result was selected for analysis.
Each subject was made to relax for minimum 5 minutes prior to performing the PFT procedure. The following parameters were recorded: 1. FVC: The maximum volume of air expired after a maximum inspiration.
2. FEV1: Forced expiratory volume in rst second) the fraction of vital capacity expired during the rst second of a forced expiration.
Recording of PFTs: The relaxed subject, in a standing position, was prepared to grip the sterile mouth piece as demonstrated to her prior to the recording. When the subject was con dent and familiar with the procedure, he was asked rst to perform maximal inspiration after a deep expiration. The subject was then instructed to expire with maximal effort (maximal expiration). The mouth piece was then removed and the actual, predicted and percentage of predicted values were printed for analysis. Each subject was asked to repeat the maximum forced expiratory effort three times, each time with adequate rest in between, and the best reading of the three was considered for analysis.

Results
Descriptive and lung function parameters for policemen are shown in different age groups inTable1 The highest values of FVC and FEV1 (4.53± 0.5 L and 3.98 ± 0.50 L respectively) were found in the age group 20-25 years old and the lowest values in the age group 45-50 years (3.62 ± 0.53 L versus 3.15 ± 0.44 L respectively) in Table 1. The highest mean value of PEFR (527.3± 97.7 L/min) was in the age group 30 -35 years old.

3-2-Prediction equations for policemen spirometric lung values: -
FVC, FEV1 and PEFR prediction equations by age and height for policemen were derived using multiple regressions (Table 3).
Control is the lung values from normal population. 1 the recreation of lung values with age is more marked in the normal subjects compared for police men ( g 1, 2, 3).

Discussion
While deriving the normal Sudanese spirometric values 1 , it has been noticed that athletes and police o cers have higher values than predicted. This raised the question if prediction equation for these groups should be separate or not. This study was designed to check this hypothesis in police o cer in Khartoum state, Sudan. The police o cers perform training in college and on job. It has been di cult to nd the needed number in each stratum due to the nature of their jobs, the aging diseases and early pension. This has limited the study between age 20 to 50 years. However, there is no prospective evidence for any association between physical activity and long-term changes in pulmonary function in middleaged and older individuals 24 .
The Normal Sudanese males has highest values of FVC and FEV1 in the age group 21-30 years old 1 while adult police male in the age group 20-25 years. The highest mean value of PEFR was in the age group 20-25 years old in adult police males while Normal Sudanese male highest mean values of PEFR were found in the age group 31-40 years old 1 .
There is high signi cant difference [P < 0.05] between male police FVC and FEV1 and control male Sudanese FVC and FEV1 in age group (20 -25) year.
Even more FVC and FEV1 of Sudanese police o cers showed higher values than other training studies. 28,29 Positive correlation between exercise periods and improvement of FVC and FEV1 values been shown in different studies. 24,28,29 The aging process itself results in a decline in pulmonary function, 30, 31 loss of lung elastic recoil, increased chest wall compliance and a decrease in the strength of respiratory muscles, which has been proposed to be the most important factors contributing to the decline in pulmonary function with age. 32 It is possible that physical activity could counteract this stiffening tendency in the chest wall. Older endurance athletes have been shown to suffer less aging-related effects on lung elastic recoil and diffusion surface. 33 In previous cross-sectional studies, regular exercise training and good physical tness have been related to better pulmonary function. [34][35][36][37][38][39] In one longitudinal study, changes in physical activity positively correlated with the level of FVC between the ages of 13-27 years, 40 Jakes et al found that, those who participated in vigorous activity showed a slower rate of decline in FEV during a 3.7-year follow-up, 41 Policemen elderly had a signi cantly higher FVC, PEFR and FEV1 than those of normal elderly Sudanese males. This result is similar to the study that compared the lung volumes and pulmonary functions of older endurance-trained athletes with those of healthy sedentary age-matched controls. 42 Older athletes, vital capacity, total lung capacity (TLC), and FEV1 were signi cantly larger than those of the older sedentary men when normalized for age and height. 42 Which agrees with us in suggesting that exercise may delay the decline in pulmonary function occurring in middle and old age. Policemen showed a slower rate of decline in [FVC, FEV1and PEFR] with age [i.e., negative correlation] as compared with other studies which conducted in different countries in Brazil, Ethiopia and the United States. 26,27 ( g 1, 2, 3).
In general, the amount of physical activity declines with age. 43 According to surveys conducted in Australia, Canada, Finland, and the United States, one-quarter to one-third of the adult population are sedentary in their leisure time. 44 Thus, it is possible that more people are expected to preserve moderate pulmonary function into old age. 24 There is signi cant correlation between PEFR and maximum expiratory pressure which is a representation of respiratory muscle strength. 45 Exercise training increases the PEFR because of an increase in respiratory muscle strength. Peak ow rate is higher in tter, healthier population such as

Conclusion
higher physical activity was related to a slower decline in pulmonary function 23 . Normal spirometric values that conducted in different countries must be reviewed again because it ignored exercise factor that slows the decline in pulmonary function with age .These ndings are potentially important from a public health and clinical point of view. Our respiratory exercise could be bene ced in obstructive pulmonary disease patients. Exercise training could be used to delay the deterioration in pulmonary function which a wants future study. Ethical considerations: Ethical clearance was approved from the ethical committee at The National Ribat University -A written consent was taken from all the participants in this study. Code numbers was used for the participants that are included in this study.

Abbreviations
Pulmonary function tests: The pulmonary function tests were carried out using portable spirometer. The apparatus provides a detailed analysis of predicted and derived values. After taking informed written consent from each subject, a detailed history was recorded to rule out the exclusion criteria.
Anthropometric measurements like height and weight were taken for these subjects.
The pulmonary function tests were repeated three times for each subject each time and the best result was selected for analysis.
Each subject was made to relax for minimum 5 minutes prior to performing the PFT procedure. The following parameters were recorded: 1. FVC: The maximum volume of air expired after a maximum inspiration. Recording of PFTs: The relaxed subject, in a standing position, was prepared to grip the sterile mouth piece as demonstrated to her prior to the recording. When the subject was con dent and familiar with the procedure, he was asked rst to perform maximal inspiration after a deep expiration. The subject was then instructed to expire with maximal effort (maximal expiration). The mouth piece was then removed and the actual, predicted and percentage of predicted values were printed for analysis. Each subject was asked to repeat the maximum forced expiratory effort three times, each time with adequate rest in between, and the best reading of the three was considered for analysis.

Consent for publication
Not applicable Availability of data and material Tables Table-1 Descriptive data and lung function for normal male police o cers by age group SD = standard deviation. FVC = forced vital capacity; FEV1 = forced expiratory volume in 1 second; PEFR = peak expiratory ow rate