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It’s well-established that obstructive sleep apnea is linked with increased heart risks. But now, a new study teases apart what exactly it is about the sleep disorder, characterized by pauses in breathing during sleep leading to disrupted sleep, that seems to predict these cardiovascular events.

Obstructive sleep apnea is measured by the number of times a person stops breathing during sleep (the apnea-hypopnea index, or AHI). However, researchers found that there were a number of other elements of sleep apnea that seemed to be predictive of cardiovascular events. The biggest one: the amount of time spent sleeping when the oxygen saturation was below 90 percent.

Other elements associated with a cardiovascular event included heart rate, daytime sleepiness, number of awakenings during the night, sleep time and leg movements, the researchers found. While the apnea-hypopnea index was associated with cardiovascular events when it was looked at by itself, it was no longer considered a significant predictor once all the other elements were factored in.

The study, published in the journal PLOS Medicine, is based on 10,149 people with obstructive sleep apnea who underwent diagnostic polysomnography between 1994 and 2010; 1,172 of those people developed cardiovascular disease.

“We believe a revision of the operative definition of OSA [obstructive sleep apnea] may be necessary, to reflect not simply the frequency of apneas and hypopneas, but the actual physiologic consequences that result — the severity of oxygen desaturation, sleep fragmentation, sleep deprivation and sympathetic activation,” the University of Toronto and St. Michael’s Hospital researchers said in the study. “It is these ‘downstream’ phenomena that we have found to be more predictive of CV [cardiovascular] risk.”

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A new study suggests that patients with spinal cord injuries could benefit from careful assessment for sleep apnoea.

Results show that 77 percent of spinal cord injury survivors had symptomatic sleep-disordered breathing, and 92 percent had poor sleep quality. The study also found that the nature of sleep-disordered breathing in patients with spinal cord injury is complex, with a high occurrence of both obstructive and central sleep apnea events. The occurrence of central sleep apnea, which requires special consideration in diagnosis and treatment, was more common in patients with a cervical injury than in those with a thoracic injury.

“The majority of spinal cord injury survivors have symptomatic sleep-disordered breathing and poor sleep that may be missed if not carefully assessed,” said principal investigator and lead author Dr. Abdulghani Sankari, physician scientist at John D. Dingell VA Medical Center and Wayne State University School of Medicine in Detroit, Mich. “Our findings help in identifying the mechanism of sleep-disordered breathing in spinal cord injury and may provide potential targets for new treatment.”

The study results appear in the Jan. 15 issue of the Journal of Clinical Sleep Medicine, which is published by the American Academy of Sleep Medicine.

“Sleep-disordered breathing may contribute to increased cardiovascular mortality in spinal cord injury patients,” said American Academy of Sleep Medicine President Dr. M. Safwan Badr, who was involved in the study. “All spinal cord injury patients should undergo a comprehensive sleep evaluation using full, overnight polysomnography for the accurate diagnosis of sleep apnea.”

Sankari and his team studied 26 chronic spinal cord injury patients, including 15 with cervical and 11 with thoracic injuries. All subjects had baseline spirometry, a battery of questionnaires and attended polysomnography with flow and pharyngeal pressure measurements.

According to the authors, this is the first study to assess sleep-disordered breathing and ventilation changes comparing two different levels of spinal cord injury — cervical vs. thoracic

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People with sleep apnoea and hard-to-control high blood pressure may see their blood pressure drop if they treat the sleep disorder, Spanish researchers report.

Patients in this study were taking three or more drugs to lower their blood pressure, in addition to having sleep apnoea. Participants who used the CPAP device for 12 weeks reduced their diastolic blood pressure (the bottom number in a blood pressure reading) and improved their overall night-time blood pressure, the researchers found.

“The prevalence of sleep apnoea in patients with resistant [high blood pressure] is very high,” said lead researcher Dr Miguel-Angel Martinez-Garcia, from the Polytechnic University Hospital in Valencia. “This [sleep apnoea] treatment increases the probability of recovering the normal nocturnal blood pressure pattern,” he said.

Patients with resistant high blood pressure should undergo a sleep study to rule out obstructive sleep apnoea, Martinez-Garcia said. “If the patient has sleep apnoea, he should be treated with CPAP and undergo blood pressure monitoring.”

The report, published in the issue of the Journal of the American Medical Association, was partly funded by Philips-Respironics, maker of the CPAP system used in the study. The CPAP system consists of a motor that pushes air through a tube connected to a mask that fits over the patient’s mouth and nose. The device keeps the airway from closing, and thus allows continuous sleep.

Dr Gregg Fonarow, a spokesman for the American Heart Association and professor of cardiology at the University of California, Los Angeles, agrees that most patients with hard-to-control high blood pressure also suffer from sleep apnoea.

“Close to three out of four patients with resistant [high blood pressure] have been found to have obstructive sleep apnoea, and this sleep apnoea may contribute to the difficulty to control the blood pressure in these patients,” he said.

Although this study showed a benefit from CPAP in controlling blood pressure, questions remain about the treatment’s overall effectiveness, Fonarow said.

“Whether these improvements in blood pressure can be sustained in the long term and will translate to improved health outcomes will require additional studies,” he said.

Source: health24

There’s more bad news for women with sleep apnea. A new study from the UCLA School of Nursing shows that the body’s autonomic responses — the controls that impact such functions as blood pressure, heart rate and sweating — are weaker in people with obstructive sleep apnea but are even more diminished in women.

Women with obstructive sleep apnea may appear to be healthy — having, for instance, normal resting blood pressure — and their symptoms also tend to be subtler, which often means their sleep problem is missed and they get diagnosed with other conditions.

“We now know that sleep apnea is a precursor to bigger health issues,” said Paul Macey, lead researcher on the study, which appears Oct. 23 in the peer-reviewed journal PLOS ONE. “And for women in particular, the results could be deadly.”

Obstructive sleep apnea is a serious disorder that occurs when a person’s breathing is repeatedly interrupted during sleep, sometimes hundreds of times. Each time, the oxygen level in the blood drops, eventually resulting in damage to many cells in the body. The condition affects more that 20 million adults in the U.S. and is associated with a number of serious health consequences and early death. Women are much less likely to be diagnosed than men.

For the study, men and women — both with and without obstructive sleep apnea — had their heart-rate responses measured during three physical tasks:

  • The Valsalva maneuver: Subjects breathe out hard while the mouth is closed.
  • A hand-grip challenge: Subjects squeeze hard with their hand.
  • A cold pressor challenge: A subject’s right foot is put in almost-freezing cold water for a minute.
In all three tests, changes to the normal heart rate were lower and delayed in patients with obstructive sleep apnea, compared with healthy controls. The researchers found that the difference was even more pronounced in women.

 

“The heart-rate results for these tests show that the impact of sleep apnea, while bad in men, is more severe in women,” Macey said. “This may mean that women are more likely to develop symptoms of heart disease, as well as other consequences of poor adaptation to daily physical tasks. Early detection and treatment may be needed to protect against damage to the brain and other organs.”
The next step in the research is to see if the autonomic responses improve with treatments such as continuous positive airway pressure (CPAP), the usual sleep apnea therapy, in which a machine is used to help an individual breathe easier during sleep. Researchers also intend to investigate the affect of other treatments.

The study was funded by the National Institutes of Health and the National Institute of Nursing Research. Other authors of the study included Rajesh Kumar, Mary Woo, Frisca Yan-Go and Ronald Harper, all of UCLA.

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Obstructive sleep apnea is known to be associated with an increased incidence of cardiovascular disease. Now a new study indicates that OSA is associated with subclinical myocardial injury, as indicated by increased high sensitivity troponin T (hs-TnT) levels. Elevated hs-TnT levels are predictive of both coronary heart disease (CHD) and heart failure (HF) in the general population. This is the first study to demonstrate an independent association between sleep apnea severity and this marker of early myocardial injury.

“Although OSA is associated with increased cardiovascular risk, a causal association has been hard to establish because of the association of OSA with other risk factors,” said researcher Amil M. Shah, MD, MPH, of the Brigham and Women’s Hospital in Boston. “In our study, we were able to demonstrate that greater OSA severity is independently associated with higher hs-TnT levels, suggesting a role for subclinical myocardial injury in the relationship between OSA and heart failure.”

The findings were published online ahead of print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

Source: Science Daily

The risk of death goes up with the severity of a person’s obstructive sleep apnea, according to a new study in Korea.

The Journal of Clinical Sleep Medicine study is the first to find that sleep apnea severity is linked with death risk in an Asian population, said researchers from Chosun University Hospital, Seoul National University College of Medicine and the Seoul National University Bundang Hospital. Previous studies had only looked at Western populations.

Researchers analyzed data from 2,240 people ages 40 and older with sleep apnea or snoring who visited the Sleep Center of Seoul National University Bundang Hospital at some point between 2003 and 2009. All the study participants underwent a full-night polysomnography testing, through which researchers were able to deduce the number of times they stopped breathing throughout the night due to their sleep apnea. They were then grouped into categories based on sleep apnea severity (no sleep apnea, moderate sleep apnea, moderate sleep apnea and severe sleep apnea).

All the participants who had at least mild sleep apnea (about 1,800 of the participants) were assigned to undergo surgery, CPAP, a mandibular advancement device, or a combination of the three.

The participants were followed up with until Dec. 31, 2011; the average participant was observed for 61.4 months, or a little more than five years. Of those with at least mild sleep apnea, 735 received treatment for the condition; the other 1,065 were not treated either because they refused treatment, they became lost during the follow-up period, they wanted to try losing weight, or they wanted to try sleeping in a different position.

Over the study period, 69 people (3.08 percent of the study group) died. Researchers found that the death rate was higher in the groups of people with more severe sleep apnea, compared with less severe or no sleep apnea. Specifically, 1.81 percent of people with no sleep apnea died over the study period, 2.18 percent of people with mild sleep apnea died, 3.54 percent of people with moderate sleep apnea died and 4.2 percent of people with severe sleep apnea died. Heart disease and strokes were the cause of about a third of the deaths.

Overall, the risk of dying was 2.47 times higher among people with severe sleep apnea compared with people without sleep apnea.

Source: Huffington Post

 

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The severity of sleep apnoea can independently predict the aggressiveness of malignant skin melanoma, according to a new study.

The research, presented at the European Respiratory Society (ERS) Annual Congress, adds new evidence to a number of studies that have found a link between cancer and the sleep disorder.

Previous studies have looked at a link between sleep apnoea and both mortality and incidence rates from cancer. Some experimental studies in mice have also shown that reduced oxygen levels in the blood, which is common in sleep apnoea, enhanced tumour growth. This is the first study in humans to look at the link between a specific type of cancer (skin melanoma) and sleep apnoea.

Researchers studied 56 patients diagnosed with malignant skin melanomas. They measured the aggressiveness of the cancer along with the presence and severity of sleep apnoea.

60.7% of the patients had sleep apnoea and 14.3% had severe sleep apnoea. The results found that the melanoma was more aggressive as the severity of sleep apnoea increased. This was the case for all three measurements for sleep apnoea severity. The severity measurements were also linked with other factors of aggressiveness, including the growth rate or the depth of invasion of the tumour.

Lead author, Dr Francisco Campos-Rodriguez, from the Hospital de Valme in Seville, Spain, said: “This is the first study in a human sample to show that sleep apnoea can worsen the outcomes of melanoma. The findings are from a preliminary small sample, but if the results are confirmed in larger studies, this would have important clinical implications, particularly as sleep apnoea can be easily treated and this could open up new therapeutic possibilities for people with both conditions. We have just begun a bigger prospective trial enrolling 450 patients with cutaneous melanoma to analyse this link further.”

 

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ResMed has announced at the ESC Congress 2013, that SERVE-HF has completed enrollment. SERVE-HF is an international, randomised study of 1,325 participants investigating if the treatment of central sleep-disordered breathing (central sleep apnea) improves survival and outcomes of patients with stable heart failure.

Approximately 14 million people in Europe are living with heart failure and central sleep-disordered breathing is known to be a highly prevalent co-morbidity in these patients. With an estimated 30-50 percent of heart failure patients potentially at risk from this condition, the results from SERVE-HF may have important consequences for the future management of these patients.

“Completing recruitment of SERVE-HF has been an important milestone in this landmark trial,” said co-principal investigator, Professor Martin Cowie of the Royal Brompton Hospital in London. “We owe much to the commitment and dedication of SERVE-HF investigators and to a strong collaboration between sleep specialists and cardiologists. We now look forward to results in 2016 and to a fuller understanding of just how important the treatment of central sleep-disordered breathing is in heart failure patients.”

SERVE-HF will, for the first time, provide conclusive evidence of the health impact of effectively treating heart failure patients who have central sleep-disordered breathing. The trial, which began in 2008, is sponsored by ResMed. Designed as an event-driven study, its completion is anticipated by mid-2015 and results are expected to be available in the first half of 2016.

 

 

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Medical Xpress reports that women diagnosed with gestational diabetes are nearly seven times more likely to have obstructive sleep apnoea than other pregnant women, according to a recent study accepted for publication in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM). Gestational diabetes causes glucose levels in the bloodstream to rise above normal levels. This form of diabetes occurs during pregnancy, typically in the second trimester. Between four and eight of every 100 pregnant women in the United States develop gestational diabetes.

The new study found a link between gestational diabetes and sleep apnoea, which causes brief interruptions in breathing during sleep. If sleep apnea goes untreated, it can raise the risk for stroke, cardiovascular disease and heart attacks.

“It is common for pregnant women to experience sleep disruptions, but the risk of developing obstructive sleep apnea increases substantially in women who have gestational diabetes,” said Sirimon Reutrakul, MD, who conducted the research at Rush University Medical Center in Chicago. “Nearly 75 percent of the participants in our study who had gestational diabetes also suffered from obstructive sleep apnoea.”

In a series of observational case control studies, researchers monitored 45 women for sleep apnoea and other sleep disruptions. The research examined sleep health in 15 pregnant women who had gestational diabetes, 15 pregnant women who did not have the condition and 15 women who were not pregnant and did not have diabetes.

The study found a strong association between obstructive sleep apnoea and gestational diabetes in this group of mostly overweight or obese women. Pregnant women who did not have gestational diabetes were able to get an additional hour of sleep and had less fragmented sleep than women who had gestational diabetes. Past research has shown lost sleep, fragmented sleep and shorter periods spent in deep sleep – all symptoms of sleep apnoea – are likely to raise the risk a person will develop diabetes.

“Based on these findings, women who have gestational diabetes should be considered for evaluation for obstructive sleep apnoea, especially if other risk factors such as hypertension or obesity are present, and women already diagnosed with sleep apnoea should be monitored for signs of gestational diabetes during pregnancy,” Reutrakul said.

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New research published in the American Journal of Physiology – Regulatory Integrative and Comparative Physiology, suggests the estimated 12 million Americans who have obstructive sleep apnea should take better care to sleep in a very dark room. Scientists at The Ohio State University Wexner Medical Center have found exposure to dim light at night can interact with sleep apnea and lead to increased levels of depression and anxiety in mice.

“Although it is unclear at the present time whether sleep apnea causes depression, both conditions are commonly seen together in patients. Our research suggests that sleeping even with a minimum amount of light may increase symptoms of depression in those with sleep apnea,” said Dr. Ulysses Magalang, director of Ohio State’s Sleep Disorders Center and a co-author of the study.

The study involved mice that were placed in sleep apnea-like conditions that mimic the repetitive lowering of oxygen levels that sleep apnea patients experience. Half were kept in normal lighting conditions during the day and total darkness at night. The other half was exposed to dim light at night using a 40-watt light bulb in the lab. The group in dim light had higher anxiety behaviors and more depressive behaviors than the mice kept in the dark environment. Scientists also observed impaired learning and memory among both sets of mice.

“Not only were these changes observed during field and maze tests, but we also recorded physical changes, including a reduction of cell size in the hippocampus, an area of the brain important in memory and spatial navigation,” said Taryn Aubrecht, first author of the study and a neuroscience graduate student at Ohio State. “The combination of dim light exposure and sleep apnea appears to result in increased depressive and anxiety-like behaviors in mice, so limiting exposure to light at night could be a very simple strategy to help patients with sleep apnea,” Magalang said. “We’re currently exploring further human testing.”

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