In a randomised, crossover study, withdrawal of continuous positive airway pressure (CPAP) led not only to a worsening sleep apnoea but also to an increase in arterial stiffness .
Obstructive sleep apnoea (OSA) is highly prevalent and is associated with increased arterial stiffness. Changes in the mechanical properties of the vessel wall related to arterial stiffening may activate several mechanisms that are also involved in the process of atherosclerosis . Indeed, arterial stiffness has been shown to be associated with incident of cardiovascular events and all-cause mortality . It can be measured by systolic augmentation of the pulse wave and is assessed by the heart rate-corrected augmentation index (AIx).
Prof. David Kim and his co-workers (Johns Hopkins University, USA) assessed whether CPAP withdrawal will increase augmentation index and how this risk factor is affected by sleep apnoea severity, age, BMI, sex, and diabetes. Patients with moderate-to-severe sleep apnoea acclimated to CPAP were recruited. Each patient underwent a polysomnography while sleeping with therapeutic CPAP or without CPAP after 2 days of CPAP withdrawal. Morning arterial stiffness was assessed with the Aix and compared between subjects on and off CPAP. The analysis included data from 69 subjects (48 male and 21 female) with complete AIx data. Subjects were aged 50.3 ± 11.3 years and had a BMI of 36.6 ± 7.5 kg/m2.
CPAP withdrawal elicited severe sleep apnoea. The Apnoea-Hypopnoea-Index (AHI) 3% was 5.8 ± 0.9 events per hour on CPAP and 57.3 ± 3.6 events per hour off CPAP. In addition, arterial stiffness worsened with CPAP withdrawal: the Alx on CPAP and off CPAP was 2.8 ± 1.9% and 6.8 ± 2.06% (mean ± SE), respectively (P=0.0001).
The change of arterial stiffness following CPAP withdrawal was not correlated with the change in AHI, age, or BMI. Although women had a higher Alx overall compared with men, the change AIx in response to CPAP withdrawal was similar. Diabetes did not influence AIx nor the magnitude of change of Alx in response to CPAP withdrawal.
The authors concluded that CPAP withdrawal acutely worsens arterial stiffness, with significant heterogeneity between subjects. Obstructive sleep apnoea severity, age, BMI, sex, and diabetes do not predict Alx or its change during CPAP withdrawal.
- Kim DE. Withdrawal from continuous positive airway pressure (CPAP) worsens morning arterial stiffness. Abstract 808, ATS 2020 Virtual, 5-10 Aug.
- Palombo B, Kozakova M. Vascul Pharmacol 2016;77:1-7.
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