Obstructive Sleep Apnoea - Manse Medical

Obstructive Sleep Apnoea

A narrow throat? Normally each of us uses small muscles in the neck to help keep the throat open.
These muscles perform actions such as pulling the base of the tongue forward, and keeping the side
walls of the throat apart. They also help coordinate such complex actions as swallowing without
allowing the throat to become blocked. When we go to sleep these muscles relax, and the throat
becomes narrower. This is a normal process. For most of us, when the throat narrows there remains
enough space for us to gently fill our lungs with air as we breathe slowly and regularly during sleep.
For some people, however, so little space is left that sucking in air during sleep becomes a bit of a
struggle. These people can develop obstructive sleep apnoea (OSA).

Definition of OSA: in deep sleep, the only muscle really contributing to breathing is the diaphragm.
The diaphragm is a flat sheet of muscle that balloons up under the lungs, dividing the thoracic from the
abdominal cavity. As it contracts, it flattens and draws the lung bases down and the lungs expand –
sucking in air through the throat, mouth and nose. If the throat is so narrow that not enough air gets
easily through to fully expand the lungs, the diaphragm will automatically contract more strongly. As it
does, air is sucked more forcefully through the throat. The throat is, at this point, a particularly floppy
tube. As air is sucked through more forcefully it tends to collapse further, making the problem worse.
In addition, the increased pressure swings through it tend to make parts of the throat vibrate,
generating a noise which is amplified through the nasal cavity and sinuses – snoring. (Almost
everybody with OSA snores).

A vicious circle: people with obstructive sleep apnoea will enter a vicious circle – sucking in air hard,
so that the throat collapses further, so that they have to suck air in harder, so that the throat . …..I
think you can see where this is heading. Ultimately the struggle for breath will stimulate the brain to
come out of deep sleep into a lighter stage of sleep, where the muscles that support the throat have a
bit of tone again. The throat opens up and breathing becomes more regular – until the brain directs
the body back into deep sleep again. For some people with OSA, the stimulus to kick the brain out of
deep sleep is not effective until the throat has closed completely, so that no air gets through. This is
called an apnoea (definition – cessation of breathing). For others, although air flow diminishes
significantly there is no complete cessation. This is called an hypopnoea.

Who gets OSA? OSA is very common in our community. At least 4% of adult men and 2% of adult
women in Australia have severe OSA. For women the problem is particularly post-menopausal. The
incidence increases with increasing weight, and with age. (Children can have OSA as either a
consequence of large tonsils, or of obesity. OSA is the main indication for tonsillectomy nowadays). If
you snore, there is a 50% chance that you have significant OSA. For many people it is simply the
anatomy of their upper airway (particularly a small lower jaw) that causes them to develop OSA.

Chronic sleep deprivation: the consequences of obstructive sleep apnoea are varied. In the first
place, it affects the way people feel and think during the day time. The impact is analogous to chronic
sleep deprivation. While some people can handle this with minimal daytime problems, most will be
more sleepy than they ought to be. Most will wake up, even after a good night’s sleep, feeling groggy.
Some will be short tempered, or have difficulty concentrating on complicated tasks. Headache in the
morning can be a symptom, as can male impotence.

High blood pressure: OSA causes high blood pressure, and should always be considered in people
who require more than two medications to control blood pressure. Treatment of OSA almost
universally reduces blood pressure.

Heart disease: there is increasing evidence that OSA causes heart attacks. In people with severe
OSA who do not accept treatment the incidence of heart disease seems to be about 3 time higher than
in similar people who do accept treatment.

Car accidents: OSA is a common contributor to motor vehicle accidents, and the state licensing
authorities in Australia have become increasingly aware of this. In general terms, people on treatment
for OSA are able to hold unrestricted drivers licenses. However, suitability for continuation of that
license will need to be carefully and repeatedly assessed by a qualified sleep specialist.

Diagnosing OSA: If you consider that you might have OSA your doctor will need to take a history of
sleep and waking habits, as well as a history from your bed partner of breathing patterns during sleep
(if possible). If OSA is considered a possible diagnosis then confirmation of the diagnosis with a ‘sleep

study’ (polysomnogram) is required. Sleep studies can be performed in a specialized facility ( a sleep
lab) or else in a person’s own home. While a sleep study at home is less accurate than a sleep study
in a sleep lab, it is able to diagnose severe OSA and is generally cheaper and more readily available
than an in-lab sleep study.

What happens during a sleep study? During a sleep study electrodes, similar to those used for
recording the electrical activity of the heart during an ECG, are connected to the scalp and face to
record brain-waves (EEG) and eye movements, as well as muscle tone under the chin. An air-flow
sensor is inserted under the nostrils, and narrow belts are worn around the chest and abdomen as
well as a small oximeter (sensor of oxygen levels) on one of the fingers – all to monitor the breathing.
Generally ECG leads are also connected to the chest, and leg movement sensors connected to one of
the thighs.

How is OSA treated? Treatment of OSA depends, once the diagnosis has been confirmed, on the
severity of the problem.

Motherhood statements: weight loss always helps. Relief of nasal congestion can be important in
mild OSA. In some people, avoidance of sleeping on the back can be important. Alcohol consumption
and cigarette smoking make OSA worse, and should be minimized or avoided.

CPAP: Constant positive airway pressure, or CPAP, is a very effective treatment for OSA. It is also
the most common treatment. When a person uses CPAP, a small mask is worn over the nose or else
over the nose and mouth. This mask is attached by a tube to a small machine beside the bad which
is, effectively, a fan-based pump. This pump sucks in air from the room, filters it, and delivers it at an
increased pressure via the mask. This helps to hold open the upper airway on a cushion or splint of
air, preventing it from collapsing during sleep. Although intrusive in the bed room, CPAP is the only
treatment that is effective in severe OSA. Most people do better if there is a humidification chamber
attached to the machine (which reduces the nasal problems that can be associated, such as
exacerbations of hay fever). CPAP can be difficult to get used to, and often considerable support is
required in the initial stages of use.

Mandibular advancement splint (MAS): A mandibular advancement splint is a dental device,
something of a cross between a mouthguard and dental plate. This device has a portion for the upper
and lower teeth, and is designed to hold the lower jaw forward during sleep. This increases the space
available at the base of the tongue (which is drawn forward slightly) and can be an effective treatment
for moderate OSA.

Surgery: many surgical procedures have been performed for treatment of OSA, and most have failed
in adults. Maxillo-mandibular advancement surgery works often, but is radical treatment that involves
dividing and advancing forward, then bone-grafting into place, both the upper and lower jaws. It is a
treatment that is reserved for people who really cannot tolerate CPAP and radically changes a
person’s appearance. In children, and in some adults, removal of very large tonsils can help.
Surgical treatment of nasal obstruction can help in people with mild problems.

This information is intended as a guide only. Information specific to you as an individual should be
sought from your family doctor or respiratory specialist.