Impact of quit-smoking time on exercise capacity in patients with stable severe chronic obstructive pulmonary disease

Objective To study the impact of quit-smoking time on exercise capacity in patients with stable severe chronic obstructive pulmonary disease (COPD).Methods Pulmonary function test (PFT) and cardiopulmonary exercise testing(CPET) were tested in 52 male patients with stable severe COPD at quit-smoking of 6 months and 12 months.Results ①IC,RV,TLC and RV/TLC,but not FEV1 FEV1 ％pred,showed differences among the two groups ( P ＜0.05).IC was significantly higher in group of quit-smoking of 12 months [(2.21±0.62) L] than in group of quit-smoking of 6 months [(1.83±0.47) L].RV,TLC and RV/TLC was significantly lower in group of quit-smoking of 12 months [(4.02±0.82) L,(7.30±1.21) L,(51.43±7.67) ％] than in group of quit-smoking of 6 months [(4.75±0.26)L,(7.71±0.84) L,(56.33±8.79)％] ( P ＜0.05).②Within CPET parameters,the level of Peak Load,Peak (v) O2,Peak (v)O2 ％ pred,Peak (v) O2/Kg,Peak (v) E,dO2/dW1,Peak O2 pulse in group of quitsmoking of 12 months [(91.21±15.12) W,(1327.21±281.42) ml/min,(63.07±17.15)％,(21.58±4.13) ml· min-1 · kg-1,(38.33±8.79) L/min,(8.67±0.73) ml · min-1 · watt-1],(l0.62±2.67)ml/beat] were higher than that in group of quit-smoking of 6 months Peak Load [(81.26± 16.32) W,(1075.18±276.45) ml/min,(54.13±16.14) ％,(17.49±4.37) ml · min-1 · kg-1,(34.29±7.12) L/min,(8.51±0.72) ml · min-1 · watt-1,(9.57±2.47) ml/beat]( P ＜0.05),the level of Lowest (v)E/(v)CO2in group of quit-smoking of 12 months [(28.38±3.4)]were lower than that in group of quit-smoking of 6 months [(31.5±3.21 )]( P ＜0.05).③Postdose improvement in IC was significantly correlated with the increase in Peak (v) O2,Peak (v) O2/Kg,Peak (v) E and Lowest (v) E/(v) CO2,but not with FEV1.Conclusions The quit-smoking of time impact on the pulmonary function and exercise tolerance in patients with stble severe COPD.Smoking cessation is still one of the most important outcome measures in patients with severe COPD. Key words: Smoke;  Quit-smoking time;  Chronic obstructive pulmonary disease; Cardiopulmonary exercise test