Relation between maximum phonation time and exercise capacity in chronic heart failure patients.
BACKGROUND
Patients with chronic heart failure (CHF) commonly fatigue easily due to low peak oxygen uptake (peak VO(2)), an important index of exercise capacity. Maximum phonation time (MPT) is widely used to evaluate maximum vocal capabilities because it is non-invasive, quick, and inexpensive.


OBJECTIVE
The aim of this study was to determine the relation between MPT and exercise capacity, and MPT required to attain an exercise capacity of ≥5 metabolic equivalents (METs) in CHF outpatients.


METHODS
Cross-sectional study.


METHODS
Outpatient cardiac rehabilitation unit.


METHODS
We enrolled 111 CHF outpatients (mean age 54.2±10.1 years).


METHODS
Peak VO(2) was assessed during cardiopulmonary exercise testing (CPX) as the index of exercise capacity. After CPX, we divided the patients into two groups according to exercise capacity: ≥5 METs group (N.=68) and <5 METs group (N.=43). Measurements of MPT were taken in the seated position. All patients were asked to produce a sustained vowel /a:/ for as long as possible and were verbally encouraged during respiratory effort.


RESULTS
After adjustment for patient clinical characteristics, MPT in the CHF patients was found to be significantly higher in the ≥5 METs group than in the <5 METs group (22.1±8.4 vs. 17.0±11.6 s, F=13.5, P<0.001). Receiver-operating characteristic curve analysis of exercise capacity of ≥5 METs extracted a cutoff value for MPT of 18.27 s, with a sensitivity of 0.76, 1-specificity of 0.33, and AUC value of 0.81 (95% CI: 0.70-0.87, P<0.001).


CONCLUSIONS
There were differences in MPT in relation to an exercise capacity threshold of ≥5 METs in CHF outpatients. A MPT of 18.27 sec may be the best cutoff value to identify people with or without exercise capacity of ≥5 METs.


CONCLUSIONS
Measurement of MPT may be a useful method for estimating exercise capacity in CHF outpatients.
Department of Rehabilitation Medicine, St. Marianna University School of Medicine Hospital, Kawasaki, Kanagawa, Japan. izawapk@ga2.so-net.ne.jp
K P
KP
Izawa
S
S
Watanabe
S
S
Tochimoto
K
K
Hiraki
Y
Y
Morio
Y
Y
Kasahara
Y
Y
Watanabe
T
T
Tsukamoto
N
N
Osada
K
K
Omiya
D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000534:rehabilitation; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D010699:Phonation / Q000502:physiology*; D012372:ROC Curve