Relation between VE/VCO2 slope and maximum phonation time in chronic heart failure patients

抄録

【Purpose】This study aimed to determine the relation between the regression slope relating minute ventilation to carbon dioxide output（VE/VCO₂ slope）and maximum phonation time（MPT）, and the MPT required to attain a threshold value for VE/VCO₂ slope of ≤34 in chronic heart failure（CHF）patients.【Methods】This cross-sectional study enrolled 115 CHF patients（mean age, 54.5 years；men, 84.9%）. VE/VCO₂ slope was assessed during cardiopulmonary exercise testing（CPX）. Thereafter, patients were divided into two groups according to exercise capacity：VE/VCO₂ slope ≤34（VE/VCO₂　≤34 group, n=81）and VE/VCO₂ slope＞34（VE/VCO₂＞34 group, n=34）. For MPT measurements, all patients produced a sustained vowel/a：/for as long as possible during respiratory effort from a the seated position.【Results】All subjects showed significant negative correlation between VE/VCO₂ slope and MPT（r=-0.51, P＜.001）. After adjustment for clinical characteristics, MPT was significantly higher in the VE/VCO₂　≤34 group versus VE/VCO₂＞34 group（21.4±6.4 vs. 17.4±4.3 sec, F=7.4, P=.007）. The appropriate MPT cut-off value for identifying a VE/VCO₂ slope ≤34 was 18.12 sec.【Discussion】An MPT value of 18.12 sec may be a useful target value for identifying CHF patients with a VE/VCO₂ slope ≤34 and for risk management in these patients.