Somnoscopy: A Closer Look at Diagnostic Techniques for Sleep Disorders

Somnoscopy is a procedure used to study the functioning of the airway in patients with obstructive sleep apnea syndrome (OSAS).

The procedure is performed while the patient is sleeping through drug induction. This test allows the otolaryngologist to assess the airway and better plan a possible surgical intervention for that patient.

SAOS

OSAS is characterized by the presence of apneas (intermittent cessation of breathing lasting more than 10 seconds) and hypopneas (apneas together with a decrease in blood oxygen levels accompanied by a transitory awakening). These episodes occur more than 10 times per hour and significant snoring occurs during sleep. Non-restorative sleep leads to daytime sleepiness. OSAS affects approximately 4% of the population, generally overweight men and occasionally with a history of high blood pressure or some type of cardiac involvement.

Different causative factors of OSAS can be obstruction at the nasal level, excess size of the tongue or tonsils, alterations in the anatomy of the larynx, malformations of the palate or obesity.

Sleep studies have long been used to diagnose OSA. This study consists of making the patient sleep and assessing their heart rate, blood oxygen levels, air flow, intensity of snoring and the frequency of apneas and hypopneas during sleep. However, this does not allow us to see directly what happens in the airway when snoring occurs and apnea occurs; the exact location of the obstruction cannot be seen.

Assessing the functioning of the airway while the patient is conscious and establishing the location of the obstruction is not an easy task, which is why a few decades ago nasopharyngeal endoscopy began to be used in patients who were induced to sleep through drugs. By inducing sleep and performing somnoscopy, it can be directly observed if the obstruction occurs at the palatal, lingual or other levels, as well as the degree of obstruction.

What does it consist of

This test can be performed on any patient with a diagnosis of OSAS who is a candidate for surgery to treat the disease, thus being able to better tailor the surgical intervention to each patient. The test lasts between 45 and 75 minutes approximately. An oxymetazoline nasal spray will be applied to the patient about 15 minutes before the test to decongest the nasal cavity and mild sedation will be induced by an infusion of propofol under the supervision of an anesthetist. muscle relaxants such as benzodiazepines are not used because they relax the airway too much and can cause obstruction phenomena leading to a false positive test result.

Once sleep is induced, it is expected that the patient begins to snore and apneas occur, always monitored. The fiberscope will then be inserted through the nose and the nasal cavity, nasopharynx, palate, base of the tongue, the rest of the pharynx, tonsils, and epiglottis will be observed. The objective is to appreciate how the airway obstruction occurs in order to better plan the surgical intervention.

In 95-98% of cases, snoring is reproduced and despite the fact that propofol alters the architecture of the sleep phases, since fewer REM phases are produced, the respiratory pattern is not altered, with which the results of somnoscopy is highly comparable to what would occur under normal conditions.

Endoscopy can have complications such as some nasal bleeding (epistaxis) after the test, a laryngeal spasm or an aspiration. Somnoscopy is contraindicated in pregnant women and in patients with allergy to propofol, as well as in patients with severe nasal obstruction or a history of aspiration.

The use of somnoscopy allows the otolaryngologist to better plan the intervention in order to operate on the structures that are really causing the obstruction and thus improve the efficiency of the surgical procedure by adapting it to each patient.

MAPFRE's Health Insurance has a wide range of specialists in otorhinolaryngology and also includes a complete Preventive Medicine Program aimed at taking care of your health. Find out about the insurance that best suits your needs.