A study of reduction in breath-holding time in smokers and recovery among ex-smokers in bus depot workers

Abstract

Background: Smoking has deleterious effects on breath-holding time (BHT), which has been used in respiratory physiology as a measure of ventilatory response. Evidences regarding assessment of the reversibility of the impact of smoking on BHT and recovery in ex-smokers are ambiguous. Hence, this study was conducted to quantify the reduction in BHT and to assess the reversibility of the same. Materials and Methods: A cross-sectional study was conducted on 84 bus-depot workers consisting of equal number of smokers, ex-smokers, and non-smokers. Breath-holding time was recorded using the mouth piece attached to the mercury manometer where the subjects were advised to blow through the mouth piece after full inspiration as long as possible till the breaking point following standard methods and precautions. Comparisons among 3 groups were performed employing one-way ANOVA and post-hoc tests. The significance of difference in BHT between the 2 categories of frequency and duration of smoking was tested using Student's t-test for independent samples. Results: BHT was found to be significantly reduced among smokers compared to non-smokers. Almost complete recovery of BHT was observed in ex-smokers. There was deterioration in BHT with increase in BMI, and a statistically significant negative correlation was observed when BHT was correlated with age, especially in smokers. Conclusion: Present study has demonstrated considerable reduction of BHT in smokers and indications of recovery in ex-smokers. Further detailed study with larger sample size, stricter definition of ex-smokers, and considering physical activity is recommended.