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What is Sleep Apnoea?
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Obstructive
Sleep Apnoea (OSA) is defined as the cessation of
airflow during sleep preventing air from entering
the lungs caused by an obstruction. These periods of
'stopping breathing' only become clinically
significant if the cessation lasts for more than 10
seconds each time and occur more than 10 times every
hour. OSA only happens during sleep, as it is a lack
of muscle tone in your upper airway that causes the
airway to collapse.
During the day we have sufficient muscle tone to
keep the airway open allowing for normal breathing.
When you experience an episode of apnoea during
sleep your brain will automatically wake you up,
usually with a very loud snore or snort, in order to
breathe again. People with OSA will experience these
wakening episodes many times during the night and
consequently feel very sleepy during the day: they
have an airway that is more likely to collapse than
normal. |
OSA can range from very mild to very severe.
The severity is often established using the apnoea/hypopnoea
index (AHI), which is the number of apnoeas plus the number
of hypopnoeas per hour of sleep - (hypopnoea being reduction
in airflow). An AHI of less than 10 is not likely to be
associated with clinical problems. To determine whether you
are suffering from sleep apnoea you must first undergo a
specialist 'sleep study'. This will usually involve a night
in hospital where equipment will be used to monitor the
quality of your sleep. The results will enable a specialist
to decide on your best course of treatment. The ultimate
investigation is polysomnography, which will include:
• Electro-encephalography (EEG) - brain wave
monitoring
• Electromyography (EMG) - muscle tone
monitoring
• Recording thoracic-abdominal movements -
chest and abdomen movements
• Recording oro-nasal airflow - mouth and
nose airflow
• Pulse oximetry - heart rate and blood
oxygen level monitoring
• Electrocardiography (ECG) - heart
monitoring
• Sound and video recording
This is a very expensive investigation, with
few centres able to offer it routinely for all suspected
sleep apnoea patients. A 'mini' sleep study is more usual,
consisting of pulse oximetry and nursing observation. Home
sleep study is becoming more popular.
The British Snoring & Sleep Apnoea
Association is able to offer the latest and most technically
advanced domiciliary sleep study equipment available. This
means we can offer a service that is in many instances
superior to that which is provided by the NHS.
Our Grey Flash Unit made by Stowood
Scientific Instruments measures the following parameters:
blood oxygen saturation, heart
rate/pulse, body movement and position
oral & nasal airflow, snoring
sound data & wave form, patient events
time, re-playable & calibrated
data, plethysmography, CPAP pressure.
The sleep study can be conducted at a time
when it is convenient to the patient, and in the comfort of
their own home. We will download the information the next
day and a written report will be available within 2-3 days.
Included in the report will be recommendations as to
treatment options. Should the patient wish, we will provide
the treatment. The private and confidential sleep study
report can be sent to the patient’s GP or Consultant if that
is their wish. There is no need for a referral, but we do
advise patients that it may be in their interest if their GP
is aware of proceedings and findings.
OSA is the commonest form of sleep apnoea,
(about 4% of men and 2% of women) but there is also a
condition called Central Sleep Apnoea (CSA). This is a
condition when the brain does not send the right signals to
tell you to breathe when you are asleep. In other words the
brain 'forgets' to make you breathe. It can also be
associated with weakness of the breathing muscles. The
assessment for CSA is often more complicated than for OSA
and the treatment has to be carefully matched to the
patient's requirements. There is also a condition called
Mixed Sleep Apnoea that is a combination of both obstructive
and central sleep apnoea.
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