Reversing Brain Abnormalities in Childhood Obstructive Sleep Apnea

Here is a news brief about childhood obstructive sleep apnea (OSA). In kids, untreated OSA can cause learning, attention, and behavioral problems. In fact, some kids with OSA are incorrectly diagnosed as attention deficit disorder. It is thought that OSA can actually damage kids' brains. A new study shows that treating OSA can reverse some of the brain damage done and improve kids' learning, attention, and behavior.

Sleep Apnea and Cancer Risk

Here is a news brief about two studies showing that obstructive sleep apnea (OSA) may increase the risk of cancer. Repetitive oxygen decreases in OSA may be the culprit. OSA is also linked with obesity, diabetes, high blood pressure, heart disease, and stroke - all of which are associated with increase risk of cancer as well.

Obstructive Sleep Apnea, Delerium, and Knee Replacement Surgery

Apparently, the incidence of post-operative delirium after knee replacement surgery is rather high - 32% according to a study. Mr. Flink and others did an experiment to see what pre-existing medical conditions are associated with post-operative delirium in knee replacement surgery patients. Their results are published in the April edition of the Anesthesiology Journal and showed that 27 of 106 (or 25.5%) patients developed post-op delirium after their knee surgery. Of note, these patients were all elderly. Among patients with obstructive sleep apnea (OSA), 53.3% had post-op delirium, compared to 20.9% of patients without OSA. After multiple statistical analyses, only OSA was consistently a significant independent predictor of post-op delirium, among the medical conditions monitored. The reason why OSA may contribute to post-op delirium is not known. The study authors mention repeated oxygen level drops as a cause, which is possible. OSA can also cause general inflammation, which apparently can increase the chance of developing post-op delirium. I wonder if delirium is more common because OSA causes sleep fragmentation, even if the oxygen levels do not decrease dangerously low. More studies are needed for sure.

Interestingly, post-op delirium still occurred in those patients who used their CPAP in the hospital, but the incidence of delirium was less than in those with OSA that did not use their CPAP in the hospital. But there were not enough patients in the sample to be statistically significant. My clinical experience is that patients do better when they bring their CPAP to the hospital for use before and after surgery. It will be interesting to see if a larger study shows an objective decrease in post-op delirium with the use of CPAP.

Room Temperature and Obstructive Sleep Apnea

Dr. Valham and others published the results of an interesting study in the April edition of the Sleep Journal. He noted that some of his patients told him they snore less when their bedroom is at a colder temperature. He then designed an experiment to test whether obstructive sleep apnea (OSA) would lessen in a colder environment as well.

He studied 40 patients by having them do 3 sleep studies, each at 61 degrees F, 69 degrees F, and 75 degrees F, but in random order. The results showed that the OSA severity was significantly higher at 61 degrees versus 75 degrees. But, the patients slept 31 minutes longer and slept significantly better in the 61 degree room. Also, those in the coldest room reported the most alertness the next morning! These results are confusing as you might think that the more severe the OSA, the lower the sleep quality and less alert someone would be the next day.

However, this just points to the fact that OSA severity does not determine completely how someone feels the next day. I have patients with very severe OSA who do not feel tired at all and tell me they sleep well each night. I also have patients who barely meet criteria for OSA who can not sleep well and have a difficult time staying awake during the daytime.

Back to this study - the researchers did not measure snoring to see if that had reduced with the cooler room temperatures. That data would be interesting to see. Also, the researchers can not explain why the OSA would be more severe as the room gets cooler. Finally, even though the subjects slept better, there was no difference in the proportion of the different sleep stages at the different room temperatures.

The implications from this study is that room temperature can help you sleep longer, sleep better, and improve your morning alertness - these results may help insomniacs improve their sleep quality.

Traumatic Memories, Emotional Reactions, and Sleep

Here is an interesting study printed in the January edition of the Journal of Neuroscience. Researchers showed study subjects neutral and traumatic pictures and assessed their ability to remember them as well as the emotional responses. For one group, they showed the pictures shortly after they woke up and the other group saw them right before going to bed. The results showed that recognition of the pictures was greater when the pictures were shown right before sleep, demonstrating that sleep (particularly dream sleep) is helpful in laying down memories. But, the emotional reactions were less if they were shown the pictures right after getting up and not allowed to sleep. The emotional reaction was the same or even intensified in those that saw the images right before bed - and this was especially true in those that had more dream sleep. This implies that depriving oneself of sleep or at least not sleeping for 12 hours after witnessing a traumatic event could reduce the negative emotional reaction to the event. This could have clinical applications in how psychiatrists treat post-traumatic stress disorder.

Obstructive Sleep Apnea Treatment With a Nerve Stimulator

Back in January of 2011, I posted about a device developed to treat obstructive sleep apnea (OSA) that could potentially replace CPAP. It's an implantable stimulator that causes the tongue to thrust forward, preventing it from collapsing backwards and blocking off the throat.

In the November edition of the Journal Sleep, Dr. Eastwood and others did a study on 21 patients with moderate to severe OSA that had failed CPAP therapy. They monitored the patients for 6 months and had repeat sleep studies to determine its effectiveness. The results showed that the nerve stimulator did decrease OSA severity and daytime sleepiness. It also improved some aspects of their sleep architecture and daytime functioning. Adherence to the device was high and it was felt to be safe with a low complication rate.

When looking at the details, the device reduced the OSA severity by 55% - from an average AHI of 43.1 to 19.5 at 6 months. But an AHI of 19.5 is considered to be a moderate amount of OSA, with 5 or less being ideal. Also, the device worked better in patients that were thinner than those that were heavier, which makes anatomical sense.

This was a small study with no control group. It will be interesting to see the results from larger trials and for a longer follow up period. One day, this device could be a good alternative to those who have failed CPAP therapy.

CPAP Can Reduce Metabolic Syndrome

Metabolic syndrome occurs when three or more of the following are present: Elevated blood pressure, elevated fasting blood sugar, increased waist circumference (think belt size), low HDL level (the good cholesterol), and high triglycerides. The metabolic syndrome increases risk for heart disease, stroke, and diabetes. In the December 15th, 2011 edition of the New England Journal of Medicine is an article about the effects of CPAP on reducing the metabolic syndrome. The study authors explain that metabolic syndrome is present in 70-80% of patients with obstructive sleep apnea (OSA). Of course CPAP treats OSA, but its effect on metabolic syndrome is not clear.

This study is high quality, as it was a double-blind, placebo-controlled, randomized, crossover design in 99 patients who received three months of either CPAP or sham CPAP, with a one month washout period between interventions. The results showed that real CPAP, when compared to sham CPAP, was able to significantly reduce body mass index, waist circumference, blood pressure, glycosolated hemoglobin (a marker of blood sugar), triglycerides, total cholesterol, and LDL (the bad cholesterol). The author explains that OSA causes dips in oxygen levels that can cause the release of certain fat-inducing hormones and damage the lining of blood vessel walls. These changes could increase the risk for metabolic syndrome, and CPAP appears to prevent this based on the study results.

I wonder if the improvement in many of the factors was due to the weight loss, rather than just the CPAP. In other words, reducing weight can improve blood pressure, lipid values, and blood glucose values. CPAP does not directly cause weight loss, but it can improve energy enough to allow patients to exercise more. They also might not eat as much food, since some patients use food to increase energy. With more energy from CPAP use, they might not eat as much.