Obstructive Sleep Apnea

Obstructive sleep apnea definition

        Obstructive sleep apnea is a pause in alveolar ventilation airflow due to upper respiratory tract, especially in the pharynx. Pharynx flattens due to negative pressure developed during inspiration and the adhesive mucosal forces tend to prevent its re-opening during exhalation. Neck flexion will aggravate this obstructive sleep apnea.

Causes of obstructive sleep apnea

        Family factors increases the risk of obstructive sleep apnea especially in patients over 65 years. Overweight is correlated with the risk of obstructive sleep apnea. The fat excess compress the airway and sleep deprivation paradoxically predispose to obesity.
Anatomical abnormalities are also a cause for this type of apnea:

• Deviated septum
• Hypertrophy of tonsillar
• Oropharyngeal polyps
• Abnormal Lueta and wave palate

        Congenital disease and endocrine pathology like acromegaly and position during sleep, hypothyroidism, neuromuscular disease, gastroesophageal reflux, the sex (female or male) are among the many factors that contribute to the obstructive sleep apnea.

        Sedatives and hypnotics have additive effects and synergistic with alcohol. Other negative influences have the narcotics, anesthetics and testosterone. Alcohol increases the frequency and duration of apnea by the combined effect of reducing muscle tone throat and depression response to hypoxia and hypercapny.

How to diagnose the disease?

        In practice, identification of patients with obstructive sleep apnea is done by questionnaire, of which the most common are:

       Stanford Sleepiness Scale (SSS) - the patient is asked to define sleepiness on a scale from 1 (awake, active, alert) to 7 (often sleep difficult to remain awake);

        Epworth Sleepiness Scale (ESS) - patient notes with points from 0 to 3 (never, rarely, often and frequently) and answer to simple questions about the appearance of sleepiness:

• Sitting and reading?
• Looking at TV?
• Sitting inactive in a public place (theater, film, meeting, etc..)?
• As a passenger in the car ?
• In the afternoon ?
• Sitting and talking to someone?
• Sitting quiet after you eat without drinking?
• In the car, if yoy stopped a few minutes?

        ESS score values vary between 0 and 24 points. On average, a patient with obstructive sleep apnea is 10 + - 5 points. The diagnosis of sleep apnea syndrome of obstructive type includes the following elements:

• Repetitive apnea (> 10 sec.)
• Respiratory effort during apnea (more than 70% of events);
• Decreases in oxygen saturation ( over 3-4% over base value;)
• "Deep breath" at the end of apnea.

        Identification of these elements requires a sleeping patient.

Obstructive sleep apnea treatment

        Obstructive sleep apnea treatment is applied in the following conditions:

• Patient has excessive daytime sleepiness;
• Cardiovascular disease;
• A polysomnographic recording to support the diagnosis.

        The only effective treatment of obstructive sleep apnea is inspiration by air pressure through an interface (nasal or facial mask) coupled to a device with sealed compressor role. The air pressure must be sufficiently large to prevent obstruction of the throat and induce apnea suppression. In patients with respiratory failure, oxygen dependent it is allowed the oxygen administration.
There are several types of devices tha can be connected to the patient during sleep.

• Type nCPAP (nasal Continous Positive Airways Pressure)
• NBiPAP type (nasal Bilevel Positive Airways Pressure).

        Most used are nCPAP, which were introduced in 1981. Pression is established during the first night of polysomnographic recording. In case of NbiPAp, the success lies in providing fixed air pressure throughout the circuit: device, circuit connection, the mask, the lungs. Among external factors, the mask has an essential role, patient is sleeping and is all night connected to the device. The criteria for choosing the mask are:

• small, but without compressing the nostrils;
• tightly mounted on the face to avoid loss of air pressure
• easy to assemble the patient;
• hypoallergenic - modern masks of silicon.