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Abstract Background The association of obstructive sleep apnea (OSA) with cardiovascular morbidity has been repeatedly reported in numerous studies and argues for treatment initiation even in the absence of significant day time sleepiness. While the long-term consequences of positive airway pressure (PAP) treatment on OSA related comorbidities like secondary hypertension are based on substantial clinical evidence, less is known about the immediate hemodynamic effects. Methods This study tried to investigate the impact of PAP treatment on different hemodynamic parameters in 48 patients with OSA by extending the standard polysomnographic assessment with non-invasive hemodynamic monitoring using impedance cardiography (ICG). On two consecutive nights under diagnostic and therapeutic conditions, polysomnographic and hemodynamic data were acquired. In addition, we subdivided the participants according to their treatment related change in stroke volume (SV) and assigned the hemodynamic measurements to the corresponding sleep stage. Results Comparing both conditions, a non-statistically significant decrease in SV and cardiac output (CO) was observed for all participants. Treatment initiation was associated with a statistically significant prolongation of the pre-ejection period (PEP) for the entire study population ( p = 0.001) and the subgroup with decreasing SV ( p = 0.008). In addition, systolic blood pressure (SBP) ( p = 0.026) and pulse pressure (PP) ( p = 0.041) were lowered significantly for patients with a therapeutically reduced SV under treatment conditions. A higher BMI ( p = 0.020) and a more pronounced reduction of the respiratory distress index (RDI) ( p = 0.030) and the arousal-index ( p = 0.021) were observed for patients with decreasing SV. Correlational analysis revealed a negative relationship between the diagnostic values for both SBP ( r =-0.324, p = 0.025) and PP ( r =-0.407, p = 0.004) with the change in SV and a positive correlation with the change of the SBP ( r = 0.317, p = 0.028) for all participants. Conclusions To conclude, our results indicate that treatment with a PAP device in patients with OSA can lead to a decrease in SV which is associated with a lowering of the SBP. This may be caused by a reduced sympathetic tone due to less respiratory events and an improved sleep profile.
Müller et al. (Mon,) studied this question.