What is Sleep Apnea?

What is Sleep Apnea?   

Sleep Apnea occurs when the patient is sleeping and failing to breath properly. Apnea simply means “pause in breathing”: When you stop breathing due to apnea episodes, the oxygen levels in your blood stream decrease. When your brain realizes that it isn’t getting enough oxygen, it “Shocks you awake” to send a message to your body to breathe again. This is often associated with a loud snort or gasp and can often be accompanied with a violent movement or positional change (which may disturb your bed partner)

Snoring can be a sign of sleep disordered breathing, but not all snorers have sleep apnea, and not all sleep apnea suffers snore.

Apneas typically last between 10 to 20 seconds (however some can last over 90 seconds!) and can occur hundreds of times every single night jolting you out of your natural sleep rhythm. Your heart rate is increased, sometime to double that of its resting rate as you wake up to restore breathing and oxygen supply.

Disordered breathing causes you spend more time in light sleep (or completely awake) and less time in the deep, restorative sleep your body and brain needs to be healthy, energetic, mentally sharp, alert and productive the next day.

As mentioned at the start of this booklet, If left untreated, poor sleep health caused by sleep apnea may lead to hypertension, heart attack, stroke, depression, diabetes, impotence, metabolic disorders, and many other serious health conditions. Sleep Apnea has also been linked to obesity and weight gain, and weight loss is typically harder for sufferers who do not treat their sleep disorder.

There are several types of sleep apnea as listed below:

OSA – Obstructive Sleep Apnea

OSA is the most common condition. As you relax into sleep, your muscles relax too, and for OSA sufferers, the upper airway relaxes too much, to the point of blocking the airway. This blockage restricts airflow to your lungs and therefore results in the failure of adequate gas exchange and causes blood oxygen levels to drop and your brain to “alert you to wake” to breath again.

Patients with OSA generally maintain their respiratory effort, ie: the muscle involved in breathing are still trying to suck air into the lungs, but the air cannot enter due to a blocked airway (Obstructive apnea)

There are 2 types of obstructions in the airway for sufferers of OSA:

  • OBSTRUCTIVE APNOEA (OA)= complete cessation of airflow for 10 seconds or greater.
  • HYPOPNEA (H) =>50% decrease in airflow for 10 seconds or greater with a decrease in oxygen saturation of >3% and/or an “arousal”

 

The Example below is a 5 Minute epoch of OSA:

 

1 is the “flow” signal from the test patients breathing cannula, when the signal is flowing ‘up’ we see inspiration, and the signal is flowing ‘down’ it is expiration, as you can see in this example, the flow signal is flat there – an obstructive apnea
2 is the signal from the oximeter which records oxygen levels, you can now see that as the patient stops breathing in 1, his oxygen level in decreases.

respiratory effort even though the patient has no airflow.

3 is the signal of the patient’s respiratory effort bands (the muscles that are involved in breathing) You can see that throughout the apnea, there is respiratory effort even though the patient has no airflow.

  NB: The amplitude of the first breath following each apnea is possible evidence of  a “Gasp” for breath as the patient is alerted by the brain that there is a reduction in oxygen levels.

 

CSA – Central or Complex Sleep Apnea

Central sleep apnea is much less common. Central apnea’s are reported when not only is there a pause in breathing like OSA, but also a pause in respiratory effort. In cases of complex sleep apnea, the patient doesn’t even try to breath. Central apnea events can occur when the patient’s airway is open or in association with OSA.

Central Sleep Apnea, Complex Sleep Apnea & Cheyne Stokes respiration are a neurological problem where the chemo-receptors, located in the brain stem that are responsible for reading blood gases (oxygen and carbon dioxide) are impaired. This part of your brain is responsible for sending the messages to your muscles to take a breath, how fast to breathe, and how hard to breathe. Impairment may be caused by years of untreated sleep apnea where the persistent fluctuations in oxygen and carbon dioxide in the blood stream have caused damage, or if there is a history of cardiac disease, stroke, trauma, or opioid, sedative and other medication use.

 

The Example below is a 5 Minute epoch of CSA

(1) is the “flow” signal from the test patients breathing cannula, when the signal is flowing ‘up’ we see inspiration, and the signal is flowing ‘down’ it is expiration, as you can see in this example, the airflow signal is flat “An apnea”
(3) is the signal from the oximeter which records oxygen levels, you can now see that as the patient stops breathing in 1 because there is no respiratory effort 2 his oxygen level in decreases.
(2) is the signal of the patient’s respiratory effort (the muscles that are involved in breathing) you can see that throughout the apnea, there is a NO maintenance of respiratory effort as the signal is flat.