[Six-minute walk test in obstructive sleep apnoea].
BACKGROUND
The aim of this study was to assess results of 6MWT in non-selected group of obstructive sleep apnoea (OSA) patients. In healthy adult subjects 6-minute walking distance (6MWD) range from 400 to 700 m. Obesity, the main symptom of OSA, is one of the factors associated with reduction of 6MWD (another common factors: older age, shorter height, female sex, pulmonary, cardiovascular and musculoskeletal diseases).


METHODS
Subjects completed sleep questionnaire and Epworth sleepiness scale before sleep studies (full polysomnography [PSG] or PolyMesam study [PM]). Consecutive OSA subjects (AHI/RDI >10, Epworth score > 9 points) were evaluated. The 6MWT, chest X-ray, spirometry, arterial blood gases, ECG, blood morphology and biochemistry were performed during trial treatment with autoCPAP.


RESULTS
We studied 151 subjects (119 males - 78.8% and 32 females - 21.2%), mean age 53.4 +/- 10.5 years. Subjects were obese - BMI = 35.7 +/- 6.2 kg/m(2) and presented severe OSA - AHI/RDI = 42.4 +/- 23.2. To assess relations between 6MWD and AHI/RDI, BMI, age and concomitant diseases we divided subjects in two groups: 1(st) with 6MWD > or = lower limit of normal (LLN) (123 pts; 81.5%) and 2(nd) with 6MWD < LLN (28 pts; 18.5%). Significant differences between groups were found for BMI, FVC (% of predicted) and Borg dyspnea scale before and after 6MWT. In multiple linear regression analysis we found significant correlation between 6MWD and BMI (beta = 0.41, p < 0.0001) and arterial hypertension (beta = -0.16, p = 0.04). Females had significantly shorter 6MWD than males (401.1 +/- 83.6 m and 451.8 +/- 107 m, respectively; p = 0.01). Difference was significant after adjustment for BMI and age (analysis of covariance) - R = 0.61, R2 = 0.38 (p < 0.0001).


CONCLUSIONS
BMI, female sex, arterial hypertension and lower FVC (% of predicted) were related to shorter 6-minute walking distance in OSA patients.
Pływaczewski
Robert
R
Zaklad Diagnostyki i Leczenia Niewydolnosci Oddychania Instytutu Gruzlicy i Chorob Pluc w Warszawie, Poland.
Stokłosa
Anna
A
Bieleń
Przemysław
P
Bednarek
Michał
M
Czerniawska
Justyna
J
Jonczak
Luiza
L
Górecka
Dorota
D
Sliwiński
Paweł
P
D000328:Adult; D000368:Aged; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D011044:Poland; D011237:Predictive Value of Tests; D012044:Regression Analysis; D020181:Sleep Apnea, Obstructive / Q000209:etiology / Q000503:physiopathology*; D013147:Spirometry; D016138:Walking