Introduction:

Sleep testing can involve various procedures oriented towards diagnosing sleep disorders or treating or following up (monitoring) such disorders. No test is perfect and physicians must weigh the quality of a test to decide how much stake to put into it and judge its influence on medical decision making and recommendations to the patient. In the extreme case, the physician may decide that a particular test is deeply flawed and its data must be discarded and decisions based on other sources of information. Alternatively the physician may decide to repeat the test. Questionnaires are also used to document specific sleep symptoms.

Polysomnography:

A polysomnogram is a sleep study conducted in a facility and the patients stay overnight under the supervision of a trained sleep technologist. Many lines of data are collected and this is probably the most reliable sleep study.

From the brain (EEG or electroencephalogram) sensors or electrodes collect information on whether the patient is asleep or awake. If sleeping, the stage of sleep is determined and whether REM (Rapid Eye Movement) is present, when dreaming usually occurs. Clearly sleep apnea refers to events during sleep, not wakefulness, and sleep apnea is usually worse during REM. The EEG can also detect seizures that may be confused with other sleep events such as REM Behavior Disorder that also has a characteristic EEG pattern. Other illnesses such as Fibromyalgia have a recognizable pattern. It is best to collect EEG data in a facility, since portable or home testing is often not adequate and overall not cost effective. A trained sleep technologist must apply the sensors or electrodes and maintain them throughout the night.

Sensors are placed over the nose and mouth to detect airflow or whether the air moves in and out of the nose and/or mouth. This data is combined with information from belts around the chest and abdomen that indicated air moving in and out of the lungs or effort of breathing. If there is no air flow at the nose/mouth (apnea) but the belts indicate chest and abdominal effort then this is an obstructive apnea, or obstruction in the back of the throat. If there is no airflow and no belt motion or lack of any breathing effort then this is a central apnea, or the brain did not give an adequate command to breathe. It is important to distinguish between these 2 apneas since they are treated differently. Obstructive apneas characteristically involve snoring while central apneas usually do not.

A very important sensor, an oximeter, is placed over a finger to detect oxygen saturation and pulse. Apneas (by definition lack of breathing) can lower oxygen if they last long enough, usually over 10 seconds. A patient with obstructive sleep apnea will intermittently lower their oxygen saturation during the night especially during REM and while supine (on their back).

An electrocardiogram (EKG or ECG) is also recorded since apneas can lead to arrhythmias and this is one of the reasons to treat.

Sensors are placed over the legs to detect leg movements that can disturb the patients’ sleep. The wires from these sensors are all placed on a jack box and this in turn is plugged into an amplifier and then the signals are transmitted to a computer. If a patient has to go to the bathroom it takes only a few seconds to unplug the jack box and place it around the patient’s neck like a large necklace and the patient can go to the bathroom.

Usually the patient arrives at the sleep lab in the early evening and leaves in the early morning. Sensor paste in the hair and body can easily be removed with water. In our laboratory we do not use oil base glues to hold sensors or electrodes in place.

Some patients worry about not sleeping at the lab, but more than 90% do since sleepiness is one of their main complaints to begin with. Rarely, a mild short-acting, modern sleeping pill is used to induce sleep that minimally affects the sleep information obtained.

Polysomnograms can be done to diagnose sleep problems, treat them, or follow up and monitor them. Often a diagnostic study is done to document sleep apnea and its severity, then a titration (therapeutic study) is done whereby PAP (either CPAP-continuous positive airway pressure, or “BIPAP”—bilevel positive airway pressure) is used to control the sleep apnea, or both are accomplished in one night using a split night study, i.e. in one night half of the study is diagnostic and the other half is therapeutic. In a split night study, the right conditions have to be present.

Links by City:

Sonno Sleep Lab of New Mexico

Let’s start with strait up CPAP, the most basic of xPAP therapy. It blows a predetermined pressure that splints the airway from collapsing as a result of an obstructive event. The same amount of pressure is provided the entire night, whether or not the person needs it. It prevents events before they happen, and if set at the correct pressure for the individual, almost all obstructive events will be prevented. It makes adjustment in airflow to maintain correct pressure at all times, as do all xPAPs; but for the most part, I think we can say its main concern is if its on or off.

An autoPAP works similar to a strait CPAP, in that it uses pressure to hold the airway open, preventing obstructive events before they even have a chance to occur for the most part. It adjusts, within the pressure settings given, so the user can have more time at lower pressures, only spending time at higher pressures when their breathing pattern indicates obstructive events are likely to occur. Its my understanding that autoPAP’s adjust their pressure fairly slowly, over several minutes and do not make rapid, drastic changes. They are pretty much equal to preventing obstructive events as strait CPAPs, before the event even starts. On the simplest level, we can think of autoPAP’s as being primarily focused on monitoring changes in airflow to predict possible obstructive events.

Regular BiPAP or BiPAP S (Spontaneous) has two pressures levels, IPAP for inhale and EPAP for exhale. It works similar to strait CPAP, in that the pressures are set based on titration results. Used to treat OSA, the pressure works much the same as strait CPAP, except that it changes from higher IPAP to lower EPAP SPONTANEOUSLY as the patient inhales and exhales. If the patient doesn’t trigger IPAP by inhaling, it will remain at the lower EPAP pressure. The advantage for some, is the reduces pressure on exhale makes breathing easier and more natural and there is less tendency to swallow air. In addition to OSA, it can also be used to treat other various respiratory disorders and in some people with CSA. It is usually as effective at preventing obstructive events by splinting the airway, as strait CPAP and autoPAP, if set to the correct titrated pressures. On the simplest level, we can think of it as being focused on changes in airflow related to inhalation & exhalation.

AutoBiPAP, is a combination of an autoPAP and a regular BiPAP, used in the treatment of OSA. It spontaneously changes between IPAP and EPAP, based on the users inhalation and exhalation. At the same time, it also adjust the over pressure ranges, within preset limits, up and down, so the user may spend more time a lower pressure settings, only increasing pressure ranges as needed when the breathing pattern indicates obstructive events are likely to occur. We can think of this as being focused on both airflow changes related to inhalation & exhalation and monitoring changes in airflow to predict possible obstructive events.

In terms of apnea, all of the previous xPAPs are primarily used to treat predominantly obstructive sleep apnea. The next two types of xPAPs are used to treat predominantly central sleep apnea and are much more complex. Up to now, we’ve been talking about a physical blockages, ‘plumbing issues’ as this article aptly puts it. With central events, you get into a lot more complex issues, using the same articles analogy, ‘electrical problems’. I am more familiar with central issues, as my diagnosis from the beginning 3 1/2 years ago was severe CSA, with over 60 centrals per hour. More recently, Complex Sleep Disordered Breathing (CSDB) was added, as my centrals events have never been well controlled with BiPAP ST, leading to numerous other issues with my sleep.

BiPAP ST, like the regular BiPAP S, will SPONTANEOUSLY change pressures from IPAP to EPAP, as the user inhales and exhales. It switches to a TIMED back up mode, based on a predetermined number of BPM (Breaths per Minute), if the user does not breath so many times per minute. In TIMED mode, the BiPAP ST is in control of switching from IPAP to EPAP though as soon as the user begins to make any effort to inhale or exhale on their own, it switches back to SPONTANEOUS mode. A lot of people are mistaken that in TIMED mode, it is breathing for you- its not; its only attempting to give you a push to breath. It cannot force air into or out of your lungs, it can only assist you. Some people with central apneas are better at taking the hint then other, so while it make work while for some, it may not for others. Another difference between how the other various xPAP’s treated OSA is that they prevented the events from ever happening for the most part; a BiPAP ST’s TIMED mode cannot do anything to prevent a central apnea before it occurs. The goal is not prevention as much as it to stabilize breathing, which the SPONTANEOUS changing in pressure rhythm can do to some degree for some people, which is why regular BiPAP S can sometimes be used for people with CSA.

While TIMED Backup Rate is needed in some cases, it can cause issues too. It assumes at 12 breaths per minute, each breath will be exactly 5 seconds long. Okay if you take a few 4 second breath cycles, but don’t push your luck and try for those 6-7 second breath cycles. Backup rate should be set a few BPM lower then your average resting BPM, but an average is just that, an average- sometime you might breath more times per minute & sometimes less. If the Backup Rate is set too low, it may not provide enough support. Its a delicate balance, which works fine most of the time, though it can feel like a Drill Sargent shouting orders at you to breath at the rate he wants you to- not fun in the middle of the night, and can disrupt sleep and breathing stability in some sensitive individuals. A BiPAP ST doesn’t care how much you breath each breath cycle either, as long as you inhale and exhale on schedule. So a user could be meeting the BPM quota, but what if they are only exchanging 25% of the air they should be? The machine is happy, thinks everything is fine, but the users body thinks otherwise.

In simplest terms, a BiPAP ST is still focused on changes in airflow related to inhalation & exhalation, as the BiPAP S was, but also focuses on the number of times you breath per minute, switching to TIMED mode if necessary in an attempt to trigger breathing. Definitely more complex then any of the other machines we’ve looked at so far, but still lacking some finesse to really deal with all the issues related to CSA or CSDB for some users, though some people with CSA and other central related issues do very well with BiPAP ST. I happened to one of them who didn’t work great for, it let me thread water the past few years, but never fully addressed my sleep related breathing disorders. Prior to the Adapt, I could not sleep without my BiPAP ST at all.

The ResMed VPAP Adapt SV is technically a BiPAP ST, and could be thought of as almost a autoBiPAP ST….but its more then that- Auto Servo Ventilation. I’ve been using it for 5+ months & am stilling trying to figure out what the ‘magic dust’ is that allows it to work so well for me. It has 2 levels, like you would expect with a BiPAP, but they are not static, not even in relationship to each other or through an inhale or exhale. It has a backup rate, like you’d expect with a ST, but its not preset, its based on your breathing history for so many minutes prior; though it does also have a ‘failsafe backup rate’ of 15 BPM, if it doesn’t have enough data points to use. The easiest way for me to describe how it works is to use my own prescription- EEP 9 (akin to EPAP or minEPAP on autoBiPAP), minimum PS (Pressure Support) 3, maximum PS 10, which means its basic operating pressure is going to be 9+3 or 12/9, but can go up to 9+10 or 19/9. Unlike autoPAP and autoBiPAP, which make gradual pressure adjustments, it can pretty much go from 12/9 to 19/9 in one breath cycle if need be, returning pretty much to 12/9 for the next breath cycle. It sounds like a dramatic change, and very anti-intuitive with everything we hear about needing to avoid to high of pressure to avoid pressure induced centrals but it doesn’t feel as dramatic as it sounds & definitely works for me personally.

The Adapt focuses on not only how many times a user breaths per minute, but also on how much air they exchange in each breath, and is the first xPAP to do so. It monitors a users Minute Ventilation (MV), which is BPM x Tidal Volume (TV, air exchanged in a single breath) and sets a Target MV, based on the users recent history. It will make changes in the inhale & exhale pressure and the length of breath cycle to guide you towards the Target MV, whether your current breathing puts you above or below it. So unlike other BiPAP, where the pressure stays the same across each IPAP and EPAP respectively, it may give me 9.0-11.0 or even more (haven’t noticed it going up as much on the on screen, live data) as my exhale pressure, changing throughout one breath. During one inhale, it might go from 12-19, especially if it senses me not inhaling. Its changing pressure support microsecond by microsecond, not over several minutes or more as we saw with the other autoPAPs. The Target MV is always changing, as its based on your own history. It can be fun for a couple minutes to attempt to match your MV to the Target MV, until you realize its a moving target and akin to chasing your own tail-lol.

So why does it work exactly- that’s still a little fuzzy, the ‘magic dust’ component I mentioned. CSA and CSDB are extremely complex disorders and its a machine built to match. It is very good at stabilizing unstable breathing of central events for some people, when all else has failed. Its almost scary sneaky, uncanny, in how it can get me to breath, even if I try to hold my breath it has me inhaling before I even realize it; the same goes for trying to breath through my mouth with a nasal mask on. So if its that great for centrals, what about obstructive events? It doesn’t do much and the the base pressure, or EEP, has to be set above were obstructive events would be cleared (or in my case, where I was comfortable, based on several years pressure on BiPAP ST). If we go back to the Drill Sargent analogy with the BiPAP ST at times, the Adapt, to me, feels like a graceful ballroom dancer who sweeps you off your feet. Dancing on air is an apt description, as is having someone reading your mind & giving you what you need before you realize you need it. If anyone can’t tell, I love my Adapt, especially since its the first thing that’s been able to normalize not only my breathing, but also my sleep on many levels neither my sleep doctor nor I anticipated. I think having more Stage 3/4 sleep in my Adapt titration then in 4 previous PSG’s combined can give a glimpse at what it can do in some cases of extremely complex sleep disorders.

The Adapt has its drawbacks- price and insurance coverage are two cannot not be overlooked. It is equal price wise to regular BiPAP ST and has the same basic requirement for documentation of medical necessity. Its not widely used and not all sleep doctors & sleep labs are familiar with it, or set up to titrate it. It is very picky about which masks are used with it, limited to 4 of the 5-6 ResMed masks being approved and able to pass a Learning Circuit which much be run any time something is changed in the circuit. It also uses a specialized hose, with an external sensor line.

The reason for the link is unclear

Adults who suffer chronic sleep problems may be more likely to try to commit suicide, US research suggests.

Doctors are being warned to be vigilant if a patient reports disturbed sleep – even if they have no history of mental health problems.

The more types of sleep disturbances people had, the more likely they were to have thoughts of killing themselves, or actually try to do so.

The study will be presented at a World Psychiatric Association meeting.

This study reinforces the fact that good sleep is vital for good physical, mental and emotional health Dr Neil Stanley Norfolk and Norwich University Hospital

The World Health Organization estimates that about 877,000 people worldwide die by suicide every year. For every death up to 40 suicide attempts are made.

Scientists have consistently linked sleep disturbances to an increased risk of suicidal behaviour in people with psychiatric disorders and in adolescents.

But it has been unclear whether the association also exists in the general adult population.

Sleep disturbance

A University of Michigan team examined the relationship over one year between sleep problems, and suicidal behaviour in 5,692 Americans. During the course of the year 2.6% of the sample had suicidal thoughts, and 0.5% were recorded as making a suicide attempt.

INSOMNIA On any given night one in three people will be struggling with insomnia Women twice as likely to be affected 10% of people have clinical insomnia Can be treated with techniques such as cognitive behaviour therapy

They looked at three types of sleep problems – difficulty falling asleep, difficulty staying asleep and waking at least two hours earlier than desired.

The researchers took account of factors such as substance abuse, depression, anxiety disorder, and physical illness, as well as social factors such as marriage and financial status.

People with two or more symptoms of insomnia were 2.6 times more likely to report a suicide attempt than those whose sleep was not disturbed.

Early morning waking was the single trait most strongly linked to suicidal behaviour.

Lead researcher Dr Marcin Wojnar said: “The presence of sleep problems should alert doctors to assess such patients for a heightened risk of suicide even if they don’t have a psychiatric condition.

“Our findings also raise the possibility that addressing sleep problems could reduce the risk of suicidal behaviours.”

Underlying link

Dr Wojnar said it was possible that sleep disorders and suicidal thoughts were both the manifestation of a troubled psyche, or that poor sleep drove people to thoughts of suicide.

Most people with insomnia manage the effects very well Dr Daniel Freeman Institute of Psychiatry at King’s College London

But he also suggested there could be an underlying physiological link between the two which was not clear.

Experts have suggested that a lack of sleep might affect the way the brain works, leading to poor judgement and less ability to control impulses.

It is also suspected that both sleep disorders and suicidal thoughts might be linked to an imbalance in the chemical serotonin, which plays a key role in regulating mood.

Dr Daniel Freeman, of the Institute of Psychiatry at King’s College London, said the study showed that insomnia was very common, and could have a significant effect on psychological well-being.

He said: “It is very plausible that suicidal thoughts, which happen when we are depressed and find it hard to think our way out of our problems, have been linked to insomnia.

“However it needs to be remembered that insomnia is very common and suicidal thoughts less so. Most people with insomnia manage the effects very well.

“Insomnia only triggers severe problems for people with a pre-existing vulnerability.”

Sleep important

Dr Neil Stanley, a sleep expert at Norfolk and Norwich University Hospital, said: “This study reinforces the fact that good sleep is vital for good physical, mental and emotional health.

“Poor sleep has long been linked with an increased risk of depression, but this study suggests that the increased risk of suicidal behaviour is not necessarily linked to depression and thus can affect those that doctors might not feel are at risk.

“It is another demonstration of the importance, both as an individual and as a society, of getting good sleep.”