[Daytime ventilatory efficiency in obstructive sleep apnea syndrome--influence of CPAP-therapy].
BACKGROUND
Obstructive sleep apnea syndrome (OSAS) is a nocturnal breathing disorder with possibly negative consequences on daytime control of ventilatory drive. We therefore investigated ventilatory efficiency, defined as the ventilatory equivalent for CO2 (VaE/VaCO2), in patients with OSAS during exercise before and under treatment with continuous positive airway pressure (CPAP).


METHODS
In 21 patients with untreated OSAS, ventilatory efficiency, described as the slope (DeltaVaE vs. VaCO2) and the lowest ratio (VaE/VaCO2 min) of the ventilatory equivalent for CO2, was determined below the anaerobic threshold using spiroergometry. A follow-up after at least 6 months of CPAP therapy was performed in 16 of these patients and in 5 CPAP-neglecting patients with OSAS, who served as controls.


RESULTS
In 21 patients with untreated OSAS, DeltaVaE vs. VaCO2 was significantly and VaE/VaCO2 min non-significantly lower, revealing better ventilatory efficiency, compared to normal values. In 16 patients, ventilatory efficiency did not change after on average 305.7 +/- 104.8 nights of CPAP-therapy, compared to 5 controls.


CONCLUSIONS
OSAS is not associated with a disturbed ventilatory efficiency during exercise. Long-term CPAP-therapy does not change ventilatory efficiency during exercise in patients with OSAS. The improved ventilatory efficiency during exercise compared to normal controls may be due to differences concerning anthropometric data (e. g., obesity, hypertension) and cardiopulmonary exercise-test (45 degrees lying position).
Duchna
H-W
HW
Berufgenossenschaftliche Kliniken Bergmannsheil, Klinikum der Ruhr-Universität Bochum, Medizinische Klinik III, Bochum. hans-werner.duchna@rub.de
Hauptmeier
B
B
Orth
M
M
Schultze-Werninghaus
G
G
Schäfer
T
T
D000328:Adult; D015992:Body Mass Index; D002940:Circadian Rhythm; D045422:Continuous Positive Airway Pressure; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012123:Pulmonary Ventilation / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D013147:Spirometry