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Superposition of hypertension and sleep disordered breathing may become the biggest killer!

Ruitong Li, Michael Rueschmanb and other researchers recently published their latest study in EBioMedicine, "A composite sleep and pulmonary phenotype predicting hypertension", assessing the relationship between sleep-disordered breathing and pulmonary and hypertension. Studies have found that establishing the relationship between sleep-disordered breathing, lung function, and hypertension helps to more accurately identify the high-risk groups of hypertension related to sleep physiology and lung function in the clinic, which may lead to early intervention and better adherence to treatment. This research was jointly completed by three laboratories, Broad Institute of MIT and Harvard, Brigham and Women's Hospital and Harvard Medical School, and Boston Healthcare System.

Ruitong Li Graduated from Harvard TH Chan School of Public Health, the main research direction is functional genomics and translational informatics. As a core research member of Sellers Lab, she has been committed to researching the relationship between sleep-disordered breathing and hypertension for a long time and has published related 13 Articles, published in The American Journal of Human Genetics, The American Journal of Human Genetics, EBio Medicine and other well-known medical journals. Another author Michael Rueschman Worked at The National Sleep Research Resource and provided information and feedback on ways to improve sleep and physiological signal data exchange and analysis through data collected from research and clinical trials. And put forward targeted sleep improvement measures for people of different ages and races, which has strong practical significance.

Experimental methods for studying the relationship between sleep-disordered breathing and lungs and hypertension

The experimental team mainly obtained experimental data from a large-scale prospective cohort study SHHS [1] to construct a CSP phenotype based on overnight PSG and vital capacity measurements. SHHS aims to study the relationship between sleep-disordered breathing, sleep apnea and hypertension in a large community study. The sleep data of the experiment mainly comes from four established cohort studies, the time span was from 1995 to 2003, and it included 9884 individuals of mixed gender and race. The search team screened 2,517 individuals with different baseline sleep and lung characteristics in different sample sizes.

Flowchart to develop cSP highly predictive of hypertension
Flowchart to develop cSP highly predictive of hypertension

Secondly, it is divided into two groups according to the source characteristics obtained from the laboratory PSG and the home sleep apnea test. Then the data were further screened to remove 337 traits that are poorly associated with hypertension and 53 traits with a missing degree greater than 30%. After excluding the unqualified sample size of hypertension, the team continued to exclude sleep and lung characteristics. A total of 110 sleep characteristics were excluded, and the remaining 12 sleep and lung characteristics such as age, gender, skin color, body mass index, waist-to-hip ratio, etc.

According to the measurement of respiratory duration in PSG, after comparing the traits of minimum, maximum, and average low respiratory duration, the results show that shorter respiratory duration is related to higher mortality and lower arousal threshold. Previously, other research teams have been using AHI to predict the relationship between hypertension and cardiovascular risk, and this research helps prove that linking multiple dimensions of sleep with other organs and systems can provide additional information beyond AHI. The predictive value of lung function suggests that multiple pathways that affect breathing during wakefulness and sleep, as well as subsequent gas exchange patterns and abnormalities in sympathetic nerve activation and endothelial function may affect the risk of hypertension. This will help doctors explore the potential clinical uses of the new phenotype, more accurately identify high-risk groups of hypertension related to sleep physiology and lung function, and achieve early intervention and treatment.

How to judge whether you have sleep breathing disorder?

Snoring can be seen as a sign of sleep-disordered breathing. Generally divided into three types: simple snoring, snoring caused by disease, and snoring caused by sleep apnea. The first two are usually caused by improper sleeping positions, allergic rhinitis or nasal polyps, which are not too harmful and can be intervened by weight control and sleeping on the side.They are not considered sleep breathing disorders.

Mild obstructive sleep apnea (OSA) may only manifest as morning dry mouth, throat discomfort, and daytime sleepiness. If the above conditions are not taken seriously, the symptoms will be further manifested as inattention, memory loss, emotional instability, difficulty falling asleep and other symptoms. The serious harm of OSA is mainly manifested in two aspects: causing intermittent hypoxia, destroying sleep structure, leading to high blood pressure, cardiovascular and cerebrovascular diseases, and premature multiple organ aging; severe cases can die from suffocation during sleep.

Obstructive sleep apnea syndrome (OSAS), as a common sleep apnea disease, is characterized by hypopnea and apnea. Hypertension is a clinical syndrome characterized by increased systemic arterial pressure. It is the most common cardiovascular disease and one of the most important epidemics in modern society.

According to a survey [2] in 2015, people with sleep-disordered breathing have a significantly higher risk of cardiovascular disease and cerebrovascular disease than people without sleep-disordered breathing, and their relative risk (RR) was 3.45 and 2.87, respectively. The risk of death from cardiovascular and cerebrovascular diseases was 13.13% (RR=2.87), while the risk of death due to cardiovascular and cerebrovascular diseases was not more than 4% for people without sleep-disordered breathing.

Hypertension and sleep-disordered breathing interact

Hypertension is the result of many factors. The above studies have confirmed that obstructive sleep apnea (OSA) is related to the increased risk of occasional hypertension and refractory hypertension and night-time physiological blood pressure drop. OSAS and hypertension often occur together, which is an important cause of secondary hypertension. According to statistics, about 50%~92% of OSAS patients have hypertension, and 30%~50% of hypertension patients have OSAS at the same time. Especially in the elderly with chronic underlying diseases and sleep disorders, the occurrence of cardiovascular and cerebrovascular accidents and target organ damage have increased, and it has become an important cause of refractory hypertension in the elderly.

The elderly population is susceptible to the combined effects of hypertension and sleep-disordered breathing

The elderly population is more likely to suffer from physiological decompensation and co-morbidities of multiple chronic diseases, with a markedly weakened state and reduced sensitivity, making them more susceptible to collapse of the upper airway and significantly higher airway resistance than the normal population, resulting in a longer duration of sleep-disordered breathing events and possible changes early in the sleep-disordered breathing process. Nocturnal hypoxia and carbon dioxide retention increase the incidence of cardiovascular and cerebrovascular accidents and target organ damage in patients and have become important causes of acute cerebrovascular disease and refractory hypertension in the elderly population.

Elderly hypertensive patients are a special population of hypertension, suffering from multi-system basic diseases and increased blood pressure at night are important characteristics of the elderly hypertensive population. At the same time, elderly hypertensive patients are prone to non-dipper changes in their blood pressure due to attenuation of physiological organs, decreased elasticity of the large arteries, weakened blood pressure compensatory regulation mechanism, and decreased sensitivity of the body's baroreceptors. Relevant studies have shown that the proportion of non-dipper hypertension in elderly hypertensive patients accounts for 78.5%. Compared with dipper hypertension, non-dipper hypertension is more likely to cause atherosclerosis and increase the risk of target organ damage. It has become an independent risk factor predicting the occurrence of cardiovascular events.

In most cases, the diagnosis of hypertension should be confirmed by home blood pressure monitoring or ambulatory blood pressure monitoring. In particular, patients who are untreated or treated and have an office blood pressure level of grade 1 hypertension (140-159/90-99 mmHg) should have their blood pressure measured using Viatom Armfit+ to avoid the development of white coat hypertension syndrome. It can also help patients with blood pressure at normal high values (130-139/85 -89 mmHg) to detect the presence of covert hypertension.

Characteristics of hypertension associated with sleep-disordered breathing in the elderly

(1) Blood pressure rises at night and in the morning;

(2) Blood pressure rhythm is disordered, blood pressure no longer drops at night, showing a non-dipper rhythm;

(3) Periodic increase in blood pressure accompanied by apnea.

(4) Poor blood pressure lowering effect with medication alone, often manifesting as refractory hypertension.

(5) Improved attainment of blood pressure control with improved sleep.