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A potentially effective treatment in preventing
¡@¡@OSA is characterized by repetitive episodes of upper airway obstruction during sleep resulting in lack of oxygen, sleep fragmentation, and frequent arousals. The major consequences of OSA include excessive daytime sleepiness, cognitive function deficits, impaired psychosocial well-being, reduced driving competence, and high blood pressure. It is common among middle-aged Chinese in Hong Kong with a minimum prevalence of 4%. ¡@¡@A case-controlled study conducted in The Chinese University of Hong Kong has previously shown a high prevalence of OSA in patients following acute ischaemic stroke (49% vs 24% in a control group). This alarming finding matches with other similar studies. Cross-sectional associations from the baseline examination of the US Sleep Heart Health Study cohort have shown that OSA was more strongly associated with reported stroke and heart failure than with coronary artery disease. A Japanese study has shown that the severity of OSA is independently related to the carotid artery wall thickness. Two recent studies in Europe have shown that patients with OSA and stroke have much lower survival rates compared to those with stroke alone. ¡@¡@Researchers at CUHK have further examined the mechanisms of stroke and found that they are likely related to repetitive surges of sympathetic nerve activity during OSA-related arousals. A case-controlled study led by Professor David SC Hui, Head of Division of Respiratory Medicine, and Professor Gregory Cheng, Head of Division of Haematology of the Department of Medicine and Therapeutics, CUHK has shown that OSA, through repeated episodes of arousals, may lead to platelet activation. Platelet activation is an important step in the pathogenesis of ischaemic stroke. The study has also found that platelet activation can be reduced by nasal continuous positive airway pressure (CPAP) treatment. Although the major indication of CPAP treatment is to relieve symptoms such as disabling daytime sleepiness, the reduction in platelet activation should be regarded as a bonus benefit especially with the growing evidence of cardiovascular consequences related to OSA. It is important to treat symptomatic patients with OSA early, with the potential advantage of preventing cardiovascular complications such as stroke. |