Effects of secondhand smoking on mucociliary clearance and autonomic nervous systems in Brazilian adults

Introduction: It is known that the damage caused by smoking can be extended to passive smokers; however there are still gaps in the knowledge regarding the damage to mucociliary and autonomous systems from passive exposure to cigarette smoke. Aim: To verify the effects of secondhand smoking on mucociliary clearance and autonomic nervous systems in adults. Methods: 44 smokers (SG), 38 passive smokers (PSG), exposed daily to cigarette smoke, and 38 volunteers for control group (CG) were evaluated. An evaluation of lung function were performed. To analyze the autonomic nervous system, heart rate variability (HRV) data were collected using a heart rate monitor at rest for 20 minutes, in the sitting position. We analyzed indexes in the time and frequency domain and also geometric indexes. We measured carbon monoxide in exhaled-air levels. Mucociliary clearance was evaluated using the saccharin transit time test. Results: The PSG (42.15±7.93years) had an average time of exposure to cigarette smoke of 19.08 ± 13.19 years with a daily exposure frequency of 7.66 ± 8.7 times per day. The SG (40.54±6.24 years) presented an active smoking history of 21.11 ± 8.53 years and consumption of 26.49 ± 26.9 cigarettes per day. The PSG presented reduced lung function in FEV1 when compared to the CG, (p = 0.0211). The PSG group presented significantly reduction on mucociliary transportability time than the CG, 13.24±5.755 and 9.85±6.89 minutes respectively (p=0.0171). No significant differences were observed between the groups for the HRV data. Conclusion: Passive smokers presented reduction in mucociliary clearance and lung function, however no changes in autonomic nervous system were observed.