Peak-Expiratory flow rates (PEFR) of healthy adult Kenyan lifetime non-smokers as seen at Kenyatta National Hospital-Nairobi.
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Background, Due to its' anatomical orientation that makes it communicate directly with the environment and share the same inlet with gastrointestinal system, the respiratory system is exposed to a lot of insults. Not surprisingly, respiratory disorders rank among the commonest causes of hospital visit. Until 1959, the assessment of lung function was limited to research laboratories, but with the advent of acceptably accurate, portable, easy to use and affordable peak expiratory flow meters the situation has since changed. Peak expiratory flow rate (PEFR) is affected by racial differences, level of activity, anthropometric values, gender, smoking, lung diseases, altitude, and geographical locations of an individual. Justification; Nairobi has no peak expiratory flow rate reference values for its population. Objectives; Broad objectives; I) To determine the peak expiratory flow rates for asymptomatic adult life time non-smokers living in cosmopolitan Nairobi. Specific objectives; I) To determine PEFR in specific age groups. 2) To determine PEFR in individuals with different heights. 3)To determine PEFR in individuals with different BMI. Study site duration; This study was conducted between December 2004 and March 2005 at Kenyatta National Hospital Study design; Cross-sectional study. Target population; Residents of cosmopolitan Nairobi whose relatives, friends, or neighbours use Kenyatta National Hospital as a referral health facility. Study population & Sampling frame; The sample frame included all healthy relatives, friends and neighbors of patients visiting Kenyatta National Hospital. The study population was derived from the sample frame of subjects meeting the inclusion criteria. Stratified sampling as per age groups and gender as detailed in the methodology, using concealed Envelopes was done to achieve the target sample size. Screening and recruitmentT; 1) Using questionnaire. 2) Using physical examination. 3) Simple randomization. Sample size; The sample size was 180 females, and 180 males . Procedure and clinical methods; After obtaining demographic and anthropometric data, the subjects were taught how to use peak flow meter, and subsequently allowed to perform the procedure three times and the best of the three readings taken as the index reading of the subject. Ethical Issues; Informed consent from the subjects and approval of the ethical committee at Kenyatta National Hospital was obtained. The research posed no risks to the subjects and the data collected from this study were strictly for research purposes. Results; All study respondents were consenting males and females of age groups from 18 to 86yrs. The males were aged between 19 -80 years while the females 18-86 years old, with mean age of 44.85 years for males and 45.31 years for females. The mean height was 163.86 centimeters for males and 159 centimeters for females. The males had a mean weight of 72.08kgs while the females had a mean weight of 70. 16kgs. The mean PEFR for females was 437.l4mls/min while for that for males was 551.3mls/min. The number of males and females were equal in the six respondent age groups according to the central limit theorem and 30 subjects per age group per gender was used to arrive at the sample size as explained in the methodology. The majority of our subjects were from Langata sub urban area of Nairobi possibly due to proximity to the recruitment center. Using Pearson's correlation coefficient PEFR showed negative correlation with age with r= •. 0.4826 for males, and -0.5206 for females (p=<O.OOl;) while PEFR and height showed positive correlation with r= 0.4662(males) and O.2912(females) (p= <0.001). There was no correlation between body mass index (BMI) and PEFR. Comparatively the mean PEFR for our subjects were less compared to Caucasian counterparts by between 12 .• 16%. Conclusion; This study concluded that the PEFR for our population of study is less than the Caucasian derived standards that are in current use locally. This has a clinical utility in asthma, as 15% change in lung functions is significant enough to qualify for reversibility of symptoms in acute attack. In the meantime it is advisable to adjust the current standard values of PEFR downward according to the findings of the few studies so far done locally to avoid the use of excess dosage of medications trying to aim at un achievable lung function values for our local population. Recommendations; There is a need for a larger study incorporating other lung function parameters to try and develop local standard lung function values with wider applicability as this study only looked at PEFR and was only limited to Nairobi population.