Diurnal PaCO2 tension in obese women: relationship with sleep disordered breathing.
OBJECTIVE
Several obese subjects show a wide array of respiratory disturbances during sleep due to an increased upper-airway resistance. The aim of the present study was to evaluate diurnal PaCO(2) tension in nonsmoking obese women and the possible relationship of this parameter with the presence of sleep disordered breathing (SDB).


METHODS
Cross-sectional study of PaCO(2) tension in obese women.


METHODS
A total of 91 nonsmoking obese women (BMI > or =30 kg/m(2), aged 42.8+/-15.7 y) were recruited and evaluated for general and anthropometric parameters, respiratory function, sleep-related symptoms, and sleep disorders of breathing.


RESULTS
A total of 10 subjects (10.9%) had diurnal hypercapnia (PaCO(2)> or =43 mmHg). Age, BMI, neck circumference, apnoea/hypopnoea index, and nocturnal desaturation (expressed as TST(SaO(2<90%)); TST(SaO(2<90%))=percentage of total sleep time with oxyhaemoglobin saturation <90%) were significantly higher in obese patients with diurnal hypercapnia, compared to normocapnic women. Moreover, hypercapnic patients had reduced forced expiratory volume in 1 s compared to normocapnic individuals. By using multiple regression analysis, the best fitting model (r=0.62, P<0.001) for predicting diurnal PaCO(2) tension in the study population showed that 24.23% of the variance may be explained by TST(SaO(2<90%)), according to the equation: PaCO(2)=0.09 age+0.07 TST(SaO(2<90%))+33.00.


CONCLUSIONS
This study suggests that severity of SDB is the most important factor in determining diurnal PaCO(2) tension in apparently healthy nonsmoking obese women.
Resta
O
O
Respiratory Diseases, Department of Clinical Methodology and Medical-Surgical Technologies, University of Bari, Bari, Italy.
Foschino Barbaro
M P
MP
Carpagnano
G E
GE
Carbonara
M
M
Stefàno
A
A
Pannacciulli
N
N
Pergola
G De
GD
D000328:Adult; D000368:Aged; D000886:Anthropometry; D002245:Carbon Dioxide / Q000097:blood*; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006935:Hypercapnia / Q000209:etiology; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D010313:Partial Pressure; D012044:Regression Analysis; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000209:etiology* / Q000503:physiopathology
D002245:Carbon Dioxide