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What are sleep apneas?
Obstructive sleep apnea is a condition characterized by repetitive and recurrent pauses in breathing (notably apneas) during the night sleep, lasting at least 10 seconds, accompanied by the reduction of the content of oxygen in the blood (desaturation).
Obstructive sleep apnea by itself is not a disease and is often considered a phenomenon not particularly dangerous and rather common. However, when sleep apneas become frequent and a significant desaturation of the blood is observed, with the arising of diurnal symptoms (usually somnolence), we speak of a true Obstructive Sleep Apnea Syndrome (OSAS).
Sleep apneas in figures
OSAS affects up to 6% of the population and is twice as frequent in males than in females, particularly in old age (peak between 55 and 60 years). OSAS, if left untreated, evolves in a pejorative sense and can cause hypertension and severe cardiovascular diseases (myocardial infarction, cardiac arrhythmias, heart failure and stroke).
The causes of sleep apneas: snoring
Sleep apneas are caused by airway obstruction due to relaxation of the body during sleep: in this phase the palate tends to collapse and cause the typical snoring.
There are special conditions that predispose to frequent sleep apneas that then flow into OSAS.
Risk factors of OSAS
- Old age
- Anatomical factors (conformation of the palate, pharynx and larynx)
- Supine position during sleep
- Large meals before going to sleep
- Use of sedatives
How to diagnose the sleep apneas?
Unfortunately, OSAS may be present for years but not recognized. Although a diagnosis of OSAS is more appropriately performed through a complex examination, called polysomnography, in a hospital environment and in a specialized contest, the oximetry can be a useful and easy alternative for a screening of OSAS in the community. Oximetry, or pulse oximetry is a method for the direct, non-invasive and continuous measurement of the percentage of oxygen saturation of the circulating arterial blood haemoglobin, by means of a device called oximeter or pulse oximeter. The most common type of pulse oximeter consists of a “gripper” or “thimble” sensor applied to the fingertip that detects the oxygen percentage bound to the blood haemoglobin circulating through the finger.
The pulse oximetry provides indirect information on the oxygenation status of the blood and is generally used to evaluate the efficiency of respiratory ventilation. What is measured is the amount of oxygen bound to the circulating haemoglobin, expressed as a percentage (also called SpO2 or percentage saturation of oxygen in the blood).
In case of normal blood oxygenation,SpO2 varies between 96 and 98%, while it falls below these values if the lungs do not adequately oxygenate the blood.
For the diagnosis of OSAS, a prolonged pulse oximetry is usually performed during night sleep. In the presence of a significant number of desaturation episodes (at least 5 episodes per hour in which SpO2 drops by at least 4% for at least 10 sec) it is possible to make an OSAS diagnosis.
When can we suspect of suffering from OSAS?
- Intermittent night snoring
- Daytime sleepiness
- Night additional symptoms such as awakening with feelings of “suffocation”, excessive movement in bed, excessive sweating in sleep, excessive nocturnal diuresis
- Diurnal additional symptoms such as headaches upon awakening, difficulty in concentrating, irritability, sexual problems
How to correctly measure the blood oxygen percentage saturation (Sp02)
- Perform the detection in a sitting position (if at rest) or lying (in case of prolonged night detection), in a quiet environment, not too bright, with a comfortable temperature
- The test should be carried out away from meals and cigarette smoke as far as possible
- Quietly breathe during the test
- Place the sensor preferably on the index finger of your right hand
- Make sure the finger is clean and there is no nail varnish or false nails
- During the test the hand must remain motionless, preferably resting on a rigid support (e.g. table), to avoid movement artefacts
- The resting measurement should be performed preferably in a three-minutes time frame, by using the average Sp02 of the period