Late-breaking abstract: Immediate effects of cigar smoking on control of breathing among young smokers

Introduction Immediate effects of cigar smoking on control of breathing have not been comprehensively investigated yet. Materials and methods 50 young smokers (average age=23±4, 32 males, mean pack-years=3.6) using cigarettes and occasionally cigars voluntarily participated in this study. 25 had mild respiratory symptoms (atopic history, mild cough and exercise induced chest tightness) and mild peripheral airways obstruction (FEF25%-75%=74.15% pred., MRS-subgroup). The other 25 had normal dynamic flows and no respiratory complaints (NRS-subgroup). Mouth occlusion pressure at 0.1 s (P0.1), tidal volume(VT), inspiratory time(Ti), expiratory time(TE), period of the respiratory cycle(TTOT), duty cycle(Ti/TTOT) and mean inspiratory and expiratory flow (VT/Ti and VT/TE) were measured before and immediately after 30 minutes of cigar smoking or equal session in the smoking area without smoking (control group). Wilcoxon signed rank and U-Mann-Whitney rank sum tests were performed for the statistical analysis. Results Immediately after 30 minutes of cigar smoking TE and TTOT significantly decreased (-9.27%, p=0.009 and -5.85%, p=0.049) whereas Ti/TE and Ti/TTOT significantly increased (+8.06%, p=0.018 and +4.02%, p=0.021) in the NRS-subgroup. In the MRS-subgroup, only Ti/TTOT was significantly altered (+2.88%, p=0.034). In the whole population (n=50) significant increase of Ti/TE, Ti/TTOT and VT/TE (+6.4%, p=0.006, +3.4%, p=0.002 and +5.8%, p=0.026) and significant decrease of TE and TE/TTOT (-7.5%, p=0.017 and -2.56%, p=0.015) were detected. Conclusions Cigar smoking has immediate effects on respiratory timing but not on P0.1 regardless of respiratory complaints and mild peripheral airways obstruction presence.