Snoring (apart from annoying for those who live or live with someone who snores) are one of the most common sleep disorders and that increasingly affect more people but, do we really know what they are and why sleep disorders occur ? .

In this article we counted on the collaboration of David De La Oliva Gómez(nurse at the Vitas Hospital in Madrid, at the San Carlos Clinical Hospital in Madrid and at the Maestranza Clinic, also in Madrid) and who has told us about the disorders of sleep more common and, especially, of SAHOS and how a sleep study is carried out .

What is sleep and what are sleep disorders?

We understand by dream (according to its “pure” definition) the ” physiological stage of the human being during which our body and our organism rest and that is necessary for the maintenance of our physiological and psychological functions ” (hence one of the Main consequences of sleep disturbances may be irascibility or alterations of moods).

The sleep cycle is formed by a REM phase (which represents approximately 25% of sleep, and is usually called “light sleep”) and a non-REM phase(phases 1, 2, 3 and 4 of sleep, which represents around 75% of sleep). For the sleep to be refreshing, there must be two or three complete cycles (each of them usually lasts around 90 minutes) throughout the night.

Although there are more than a hundred different sleep disorders, we are going to focus, with the help of David De La Oliva Gómez , on OSAS or obstructive sleep apnea and hypopnea syndrome. Sleep disorders are, therefore, the alterations that cause our rest cycle to be affected and we can not maintain adequate sleep patterns.

Recently, our colleague Rocío Pérez told us about the most common sleep disorders and the treatments each one has.

What is done to study the dream?

To be able to proceed with the diagnosis and schedule a treatment, David De La Oliva tells us that what is usually done is a sleep study or polysomnography . This study can be done at the patient’s home, although the best way to do it (and also the most reliable, since at home we are at the expense of the patient following all our instructions) is with the patient admitted.

The “gold standard” (the world reference) to perform this study is through a nocturnal polysomnography . For its realization, the following registers or measurements can be realized (all or some of them):

• Encephalogram record : is a record of brain activity during sleep in all its phases (REM phase and NON REM phase, composed of phases 1, 2, 3 and 4). As indicated above, in order for the dream to be a reaparator, two or three complete cycles of sleep must occur.
• Oxygen saturation record : as we sink into a deeper sleep, oxygen saturation decreases, and any pathology related to sleep will cause it to descend more markedly .
• Registration of movements : a record of abdominal movement, leg movements (there are pathologies associated with OSAHS such as restless legs syndrome or periodic movements) or an electro-oculogram (recording of eye movement during sleep) can be made ).

In addition to the aforementioned points, a resgry of snoring, of the position adopted when sleeping and, especially, of the air flow must also be made .

SAHOS: obstructive sleep apnea and hypopnea syndrome

The OSAHS is the most common sleep disorder and by which the largest number of tests related to the study of sleep are performed. As for the types of apnea, we can find the following:

• Obstructive apnea : characterized by the relaxation of the soft tissues of the back of the throat or by a narrowing of the same.
• Central apnea : occurs when the brain stops sending respiratory stimuli during short episodes of time , which causes irregularities in breathing ( cerebrovascular accidents can be a trigger for this type of apnea due to brain damage suffered by the patient).
• Mixed : usually begins as a central apnea and ends with a component of obstructive apnea.
• Hypoapnea : it is a reduction of the respiratory signal of between 30-90% for more than ten seconds or a marked decrease of the thoracoabdominal summation accompanied by an oxygen desaturation of more than 3% and / or a micro awakening on the EEG (electro encephalogram).

In addition, there are two other data that we must take into account:

• Respiratory efforts associated with micro-awakenings (ERAM) : they are periods of more than ten seconds duration with a progressive increase in the respiratory effort of the patient.
• Hypopnea apnea index (AHI) or respiratory alteration index (ARI) : it is the parameter that is used most frequently to assess the severity of respiratory disorders during sleep, and consists of adding the number of apneas, hypopneas and ERAM per hour of sleep (or per hour of registration in case we use a respiratory hazard). The IAH and the IAR are considered from the practical point of view as a superimposable term, that is, that the ERAM are included within the hypopneas .

One of the most common consequences of apnea is the feeling of being dust during the day ( excessive daytime sleepiness ) and falling asleep anywhere. Obesity and smoking are the main risk factors for this disease.

Treatment of SAHOS

The first step in the treatment of OSAHS is usually the recommendation to lose weight to the patient, since obesity is an important risk factor in these sleep disorders.

Another form of treatment, which can be performed at the patient’s home, is through the use of a CPAP , which is a hospital device equipped with a mask and whose goal is the opening of the airways through increased pressure that the machine introduces the patient. The masks and machines must be adapted to the patient according to the degree of affection it has .

Interpretation of the polysomnogram

In order to explain to you as clearly as possible how a polysomnogram is interpreted, David De La Oliva Gómez has provided us with the images that we are going to analyze below:

Main screen

In this screen we must pay attention mainly to three of the parameters that are measured:

• In the first place, the parameter ” FLUJ + FLUJ- ” is the one that will indicate us, when the line is flat (or almost flat), the moments in which episodes of apnea occur , that is, when the patient leaves to breathe.
• Secondly, the parameter ” SpO2-SpO2 + ” is the one that will measure oxygen saturation , which, as we will see in the following image, decreases when episodes of apnea occur.
• And finally, the parameter ” RONQ + RONQ- ” will be responsible for indicating when the patient’s snoring occurs .

 Interpretation of the data

In the image that heads this point, we can see indicated in several colors the moments that interest us:

• Framed in green we can see how the snores , which are the ripples that are seen in blue, coincide with the ripples that occur in the parameter “FLUJ + FLUJ-” , corresponding to the airflow of the patient.
• Surrounded in red , we have the moments in which the patient’s apnea occurs, in which the line of the air flow tends to be almost horizontal . These episodes we can observe that they are following immediately to the moments in which the snoring occurs.
• And surrounded in purple , we can observe how the oxygen saturation decreases in the moment before the snoring occurs .