Obstructive sleep apnea is a syndrome that affects one billion people worldwide, according to the latest epidemiological studies. Half of the cases present at least moderate severity.
This disease basically consists of a blockage of the patient’s airway that prevents normal breathing.
Pauses in breathing occur repeatedly during sleep and can be partial (hypopnea) or total ().
In any case, these apneas have important consequences on the health of those who suffer from them, as well as causing logical daytime sleepiness that can be the cause of, for example, traffic accidents.
And pauses in breathing can cause neurocognitive disorders or cardiovascular events, especially in high-risk individuals.
One of the characteristics of this pathology is its heterogeneity, since both its severity and its symptoms vary greatly in the general population, being more frequent in the elderly and obese people.
Measure the frequency, duration and depth of the lack of oxygen in the blood
Once a patient is diagnosed with sleep apnea, specialists determine its severity using the apnea/hypopnea index.
According to this method, a person is considered to have obstructive sleep apnea when they have a rate of more than 5 apneas or hypopneas for every hour of sleep.
According to this scale, more than one billion people in the world suffer from obstructive sleep apnea, although not all of these patients have the secondary symptoms that we have listed.
ODI Index
Another index is also often used, the so-called ODI, which is used to measure the intermittent lack of oxygen supply (oxygen desaturations) due to respiratory pauses in apneas, and which can cause pathophysiological complications and adverse events, sometimes fatal.
As he explains Doctor Miguel Angel Martinez-Garciapulmonologist, director of the magazine and member of (SEPAR):
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“These metrics have been used (and continue to be used) classically to quantify the severity of obstructive sleep apnea.”
But in clinical practice we have observed that these ways of assessing apnea severity have limitations since they only measure the frequency of apneas, hypopneas, or oxygen desaturations, but not other important characteristics such as their length or intensity.”
nocturnal hypoxic load
For this reason, we continue to analyze newer alternative metrics that better capture the severity of grief and its pathological consequences.”
One of these new metrics is the obstructive sleep apnea-specific nocturnal hypoxic load.
With this method, specialists are able to quantify in a single easy-to-measure variable (using specific software) both the frequency, the duration and the depth of the lack of oxygen in the blood (hypoxemia) related to apneas.
In this way, specialists can more accurately classify patients with high-risk obstructive sleep apnea, who may end up suffering adverse cardiovascular events.
Relate the load of oxygen in the blood with the serious consequences of apnea
This new form of measurement, published in , the SEPAR scientific journal, is for the authors “one of the most promising metrics to replace traditional indices in the not too distant future, according to the results observed to date in risk assessment cardiovascular disease of obstructive sleep apnea”, although further studies are still needed, explains the doctor.
“In this sense, SEPAR is already finalizing a prospective study in which, in addition to cardiovascular results, it is assessed whether the hypoxic load is higher than the usual metrics in its relationship with the incidence of neurocognitive or metabolic diseases,” he adds.
A technically easy measurement
The measurement of the hypoxic load does not represent a major technical challenge for the polygraphy or polysomnography equipment with which sleep studies are carried out both at home and in the laboratory, since it can be analyzed with the usual channels used in carrying out tests. sleep tests incorporating specific software for its calculation.
Finally, the authors consider that, if the results published to date are confirmed, the hypoxic load is a variable that should be progressively incorporated into the laboratories of the , since it would allow more precise decisions to be made about those individuals with obstructive sleep apnea who would require treatment. with (or its alternatives) to avoid the negative consequences of this pathology.