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Use of CPAP Reduces Arterial Stiffness in Sleep Apnea Patients

 

By Admin

 

Morning arterial stiffness, a common comorbid condition among sleep apnea patients, has shown consistent advancements in patients who stop using CPAP, according to a new study conducted by researchers at Johns Hopkins University. The study, presented at this year’s virtual ATS International Conference, concluded that CPAP withdrawal acutely worsens the augmentation index (AIx), which, along with pulse wave velocity, is a primary measure of arterial stiffness. This means that each morning after ending CPAP treatment, this condition consistently progresses, and often at a rapid rate. This was found to be the case regardless of other factors such as age, weight, or gender. Even the severity of the condition itself did not appear to affect the rate of progress once PAP therapy had seized. Morning arterial stiffness can develop with age and is often related to arteriosclerosis, which reduces blood flow to the heart. If left untreated, artery stiffness can lead to more serious cardiovascular events such as myocardial infarction and stroke, the two leading causes of death in the western hemisphere. This is yet another example of how important treatment adherence is for overall health and longevity, as well as a reminder of how common these comorbid conditions can be for those with sleep apnea. As research continues to uncover further benefits to routine PAP therapy, patients all over the world are learning to accept this standard treatment as a way of life, and avoiding the serious consequences of noncompliance.  

Morning Arterial Stiffness

Arterial stiffness can occur due to aging, poor diet, lack of physical activity, weight, or genetics, but morning arterial stiffness specifically occurs in the early hours after a night of sleep. Often, this is due to blood pressure surges from other health problems, including sleep apnea itself. It is not uncommon for blood pressure to increase at the point of waking, but some people experience exceptionally high surges that can cause other health problems. Doctors refer to this as morning hypertension, and for those with sleep apnea, it is a very common occurrence. When the condition leads to arterial stiffness, it becomes harder for the heart and arteries to deliver blood (and therefore oxygen) to the tissues and organs of the body, a condition also known as ischemia. Arterial stiffness is a prognostic indicator of many types of cardiovascular and coronary health problems, conditions closely associated with sleep apnea. Studies in the past have found that obstructive sleep apnea (OSA) increases the risk of coronary artery disease by 30 percent and stroke by up to 60 percent. Recent statistics published this year by the journal Circulation show that cardiovascular disease (CVD) has been the most common underlying cause of death in the world since 2015.

 

While arterial stiffness can be mild in terms of symptomatic effects, it is an indicator of more serious cardiovascular problems and should be treated accordingly. Thus, from a perspective of integrated or comprehensive care goals, PAP therapy represents a single, critical component of a larger picture of long-term treatment and prevention. In addition to regular use of CPAP, this often includes lifestyle changes such as weight control, exercise regimens, and proper sleep hygiene. In one of the largest, multi-center studies on sleep disorders and heart health in the U.S., the Sleep Heart Health Study of the National Heart Lung & Blood Institute found that OSA was associated with a high risk of ischemic stroke and post-stroke mortality. What’s known as the Ischemic cascade can be triggered by arterial stiffness during sleep and early morning, leading to a cumulative series of events as the body responds to the loss of blood-oxygen in the brain. This condition can also lead to other types of coronary artery disease such as angina (chest pain) or congestive heart failure, as well as cerebrovascular disease, which occurs when the arteries of the brain become damaged. According to the Centers for Disease Control and Prevention (CDC), roughly 650,000 Americans die from heart disease each year. In 2016 alone, coronary heart disease caused the most deaths in the U.S. related to CVD (43 percent), followed by stroke (17 percent), high blood pressure (10 percent), heart failure (9 percent), and other diseases of the heart and arteries (roughly 20 percent combined). Each of these conditions is a common comorbid development among sleep apnea patients, and many have shown signs of reduction with use of CPAP. The more research that is conducted using PAP therapy devices, the more potential we are seeing in this gold standard treatment.  

The Takeaway

The Johns Hopkins University study, titled “Withdrawal from Continuous Positive Airway Pressure (CPAP) Worsens Morning Arterial Stiffness,” examined the effects of CPAP withdrawal on the augmentation index. The augmentation index, or AIx as abbreviated, is a measure of the ratio of artery augmentation to the level of pulse pressure from the heart. This is the force that the heart generates each time it contracts and expands in a cardiac cycle. Like pulse wave velocity (PWV), the augmentation index is derived from the blood pressure waveforms through the body. Higher values of AIx indicate drops in pressure and increases in arterial dysfunction. Using a single-center randomized crossover study, the Johns Hopkins investigators examined patients with moderate to severe OSA who were currently using CPAP regularly. They then compared the AIx of patients on and off CPAP using paired differences tests and examined the change in the readings. To ensure that other variables were not affecting the outcomes, they also used two-way analysis of variance (ANOVA) methods to examine any changes due to sex, age, diabetes, body mass index (BMI), or sleep apnea severity. What they found was that not only did withdrawal of CPAP allow the artery stiffness to worsen, but the level of progression was consistent regardless of other parameters. These results, presented online for the American Thoracic Society’s 2020 International Conference, showed audiences a clear relationship between PAP therapy compliance and cardiovascular outcomes. While this link continues to be debated as researchers look further into the often complex interrelations between these common conditions, studies like these provide further evidence of the benefits of CPAP to overall health and quality of life, something every patient should keep in mind when considering the importance of continued treatment.  

 

Sources

Atherosclerosis - https://pubmed.ncbi.nlm.nih.gov/23031362/

American Journal of Physiology: Heart and Circulatory Physiology - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761347/

CDC.gov - https://www.cdc.gov/heartdisease/facts.htm

Circulation - https://www.ahajournals.org/doi/10.1161/CIR.0000000000000757

Expert Review of Cardiovascular Therapy - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4234108/

Frontiers in Cardiovascular Medicine - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6008540/

Journal of Clinical Hypertension - https://onlinelibrary.wiley.com/doi/full/10.1111/jch.13140

Journal of Hypertension - https://pubmed.ncbi.nlm.nih.gov/12473865/

Journal of Sleep Medicine and Disorders - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6340906/

MDMag.com - https://www.mdmag.com/conference-coverage/ats-2020/cpap-negative-sleep-apnea-patients

Nature and Science of Sleep - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6109653/

SleepData.org - https://sleepdata.org/datasets/shhs