Obstructive Sleep Apnea Diagnosis

What is Obstructive Sleep Apnea Syndrome (OSAS)?

OSAS is caused by a recurrent collapse of the upper airway during sleep, resulting in complete (apnea) or partial (hypopnea) cessation of airflow. This leads to micro-awakenings and nocturnal hypoxemia. OSA severity is expressed by the apnea-hypopnea index (AHI), defined as the number of apneas and hypopneas per hour of sleep.

Why do the upper respiratory tract collapse?

The mechanism by which the upper airway collapses is not fully understood but is multifactorial and depends on many factors such as innate anatomical alterations such as facial elongation, retrognathia or micrognathia, mandibular hypoplasia, enlarged soft palate and hyoid bone located inferiorly (increased pharyngeal length as measured by mandible-hyoid plane distance), oropharyngeal soft tissue hypertrophy: tonsillar and lingual, obesity, [body mass index (BMI) ≥ 30 kg/m2 ], increased neck circumference, pharyngeal neuropathy, and fluid displacement to the neck.

What are the consequences of apnea?

The direct consequences of collapse are intermittent hypoxia and hypercapnia, recurrent awakenings, and increased respiratory efforts, leading to secondary sympathetic activation, oxidative stress, and systemic inflammation. Excessive daytime sleepiness is a burden and a risk for most patients. OSAS is also associated with cardiovascular comorbidities, including hypertension, arrhythmias, stroke, coronary artery disease, atherosclerosis, and increased overall cardiovascular mortality, as well as metabolic dysfunction.

Suspect diagnosis: signs, symptoms, and tests of drowsiness.

The correct approach to a person who reports daytime sleepiness and/or habitual and persistent nocturnal snoring begins with looking for specific and non specific signs and symptoms for sleep apnea.

Symptomatology

Daytime symptoms, including the following:

• Tiredness when waking up
  Poor concentration with memory impairment
  Morning headaches or sore throat or dry mouth
  Mood disorders (depression, anxiety)
  Excessive daytime sleepiness, which is a potential cause of accidents and trauma, not only to the patient but also to third parties
  Atrial fibrillation or cardiac arrhythmias
  Gastroesophageal reflux
  Reduced libido

Nocturnal symptoms, which include:

• Snoring
  Breathing pauses
  Sleep fragmented by frequent awakenings
  Awakenings with a feeling of suffocation
  Nocturia (the need to urinate during the night)
  Night sweats

Many people do not report having sleep disorders, either because they are asymptomatic, or because they do not realise they have the problem.

Therefore, it is important to apply specific questionnaires to assess the risk of an individual having OSA and so the STOP-Bang questionnaire is used. To assess and quantify daytime sleepiness, the Epworth scale is used.

I propose and recommend the patient's home polygraph in his usual condition during a normal night's sleep.

Pros:

• The execution of the examination at home is a favourable condition because it allows the patient to rest peacefully, avoiding the various psychological and practical discomforts and in conditions similar to those of every night and represents a practical and cost-effective alternative.

Contra:

• The polygraph that is used is not complete with all the sensors, it may be without the sensors for electroencephalography, for oculography and for electromyography.

I propose a polygraph that is "an innovative wrist device (FDA approved and CE certified).

• It's disposable!
  No risk of infection!
  It does not require returning the instrument, sanitising it, downloading data, and recharging.
  This device is worn like a wristwatch.
  It features a single finger-mounted biosensor, allowing for simplified use without wires, nasal cannulas, or breathing belts.
  It is intuitive and convenient to use.
  Patients wear this device at night in the privacy of their own bedroom, ensuring an undistorted sleeping environment.
  A full study report is generated in the morning just a few minutes after the data is downloaded, allowing the patient to receive immediate treatment.
  Unlike other portable devices, in addition to providing quantifiable information about apnea, it detects detailed sleep information, clinically comparable to data obtained in a sleep laboratory so you can be sure that the patient is actually sleeping.
  

Its salient features are:

• Sleep summary: with measurement of the actual sleep time, as well as the total recording time.
  Respiratory indices (pRDI- pAHI- ODI- pAHIc).
  Oxygenation and pulse information.
  Histogram: All PAT Respiratory Events- Body Position/Snoring-Oxygen/Pulse – Sleep Stages.
  Statics on body position and snoring.
  Information about sleep status (REM - light sleep - deep sleep - wakefulness).
  Classification of OSAS against AASM guidelines (mild-moderate-severe).

How is the severity of OSA classified?

The severity of OSA is clinically distinguished by the number of apnea-hypopnea per hour of sleep and the apnea-hypopnea index (AHI). AHI <5 is defined as no sleep apnea, AHI 5-15 as mild OSA, AHI 15-30 as moderate OSAS, and AHI >30 as severe OSA. Asymptomatic subjects with an AHI between 5 and 15 events per hour do not require ventilation therapy. The AHI, as an indicator of OSA severity, neglects the intensity of desaturation and awakening events and correlates inconsistently with OSA-related complications.

Once the diagnosis of OSA has been confirmed after a home polygraph, how can I proceed?

First of all, general advice is given: Behavioural changes, Weight loss, Aerobic exercises, Oropharyngeal exercises, Sleeping in lateral pressure instead of supine, Sleep hygiene measures Positive pressure devices (PAPs). Mandibular Advancement Devices (MADs) Surgical Procedures Bariatric Surgery (for Weight Loss) Uvulopalatopharyngoplasty. Glossoplasty Maxillomandibular Advancement. Electrical Stimulation of the Hypoglossal Nerve.

For the treatment of medium-severe apnea, the gold standard is represented by the use of CPAP: this acronym is the acronym for Continuous Positive Airway Pressure, i.e. continuous flow positive pressure Ventilation therapy can be practiced with the ventilator in Cpap or AutoCpap mode. Adherence to therapy is arbitrarily defined as adequate if ventilation is performed for 4 or more hours per night for at least five nights per week. Unfortunately, reported non-adherence rates range from 46 to 83 percent.

How is therapeutic pressure calculated?

The fan set in Cpap mode delivers the air at a fixed pressure. AutoCPAP, on the other hand, modifies the pressure in relation to what its software identifies as the patient's needs, moment by moment. The specialist doctor sets a range of pressures that the machine can then adjust autonomously, taking advantage of the software's ability to identify the pressure needed at that moment. After diagnosing Osas with a polygraph used at the patient's home and evaluating the need to carry out ventilation therapy, I recommend the use of an AutoCpap ventilator, set in Automatic mode, for a few nights, at least five-six, after which I evaluate the memory card, which each ventilator is equipped with, to verify the pressure that has eliminated apnea and other respiratory disorders and then applying mathematical formulas, I set the pressure values on the ventilator set in CPAP mode, which I consider therapeutic because it is effective in eliminating respiratory disorders. AutoCPAP ventilators can operate in both CPAP and autoCPAP modes. So I personalise the pressure which I then recheck periodically after ten days, after three months and even after six to twelve months. The ventilator is used in AutoCpap mode only if CPAP compliance is unsatisfactory.

Which fan?

The requirements, as well as the level of coverage for your CPAP, vary depending on your policy. To make sure that you use the equipment regularly and correctly, some insurance companies require that you undergo a trial for several months before your current CPAP therapy ventilator concession practice is approved, while other insurance companies may have you rent or buy the machine. All health insurance companies have contractual partners for the devices in question. Costs that exceed the fixed costs of cheaper devices (ventilators, masks) are borne by the insured person. The patient can always choose another device or a more suitable mask for an additional fee. As a patient you are entitled to receive a device that can be new or refurbished. There is no entitlement to a brand new device. However, the sanitized device is tested for the highest standards of safety and hygiene. Information about the frequency of use of the machine is transmitted to the supplier and this information is handed over to the insurance company. If you don't use the CPAP machine as you should, your insurer may not pay for the equipment. Many insurance companies, as well as the Centres for Medicare and Medicaid Services, require patients to use the machine for at least four hours a night for 21 days during a consecutive 30-day period. In Italy, for patients who have been diagnosed with OSAS, in order to take advantage of CPAP therapy it is essential to go to the attending physician who will forward the documentation to INPS, then he will have to go to a patronage that will request the INPS for the forensic medical examination for the recognition of disability. Once the decree of disability has been obtained, he can go to the competent ASL (Prosthetics or Rehabilitation Office) to request a ventilator that will be delivered to his home within a few weeks. Throughout the period between diagnosis and the start of therapy, you will have been advised or warned not to drive. Although there is no specific reporting requirement for sleep apnea, as a person concerned you have an important responsibility to ensure your safety and that of other road users. The alternative may be to rent or buy a fan. The cost of an excellent fan is about a thousand euros and its lifespan is at least seven to eight years; To this must be added the annual costs of the rest of the consumables, which can affect about three hundred euros.

Sleep Apnea, Driving Skills and Responsibilities

In Italy, being affected by OSAS involves a certain degree of civil disability, around 35%, which allows you to have the ventilator on loan for free use and the annual consumables: dust and antibacterial filters, masks and circuits (connection tubes between fan and mask) free of charge but also accept some obligations inherent in the issuance or renewal of the driving license. European states have implemented a European directive dated July 2014 which states that drivers diagnosed with OSAS can have their driving licences withdrawn until they are properly treated and in case of renewal are subject to a periodic medical examination, at intervals that do not exceed three years for drivers in group 1 (light vehicles) and one year for drivers in group 2 (heavy vehicles).

The clinical efficacy of CPAP may be hampered by its often low compliance rate, prompting a substantial proportion of OSA patients to seek treatment alternatives. The most studied surgical procedures for adults are uvulopalatopharyngoplasty (UPFP) and maxillomandibular advancement (MMAS).

Uvulopalatopharyngoplasty (UPFP)

UPFP involves the removal of the uvula and the back of the soft palate. It expands the oropharyngeal airway and reduces pharyngeal collapse by altering the soft tissues of the upper airway, including the lateral walls of the pharynx, the base of the tongue, and the palate. Currently, UPFP can be performed with the aid of a laser and can be combined with surgery at other sites of the airway (multilevel surgery). UPFP is effective in treating patients with OSA, but efficacy is reduced in the long term. The American Academy of Sleep Medicine does not recommend UPFP as the sole surgical procedure in the treatment of OSA. Palatal resection techniques such as UPFP are currently considered obsolete and are being replaced by modern reconstructive techniques, such as expansion sphincter pharyngoplasty, due to the improved clinical outcome and fewer side effects.

Pros:

• AHI and lower blood oxygen saturation are significantly improved after surgery, the diameter of the oropharyngeal cavity is significantly increased.

Contra:

• In patients with severe OSA, its effect on AHI is limited, and long-term adverse effects have been reported Limitations of the UPPP include its inability to improve the lateral dimensions of the upper airway, to address retroglossal collapse, or to address reduction in upper airway dilator muscle tone.

Radiofrequency (RFTA) and Transoral Robotic Surgery (TORS)

Radiofrequency tissue ablation (RFTA) and transoral robotic surgery (TORS) are the methods used in OSAS surgery. The TORS technique was found to be more effective than RF in terms of reducing the ahi value, correcting the minimum value of arterial oxygen saturation, and decreasing the Epworth Scale score for somnolence, duration of hospitalization, and duration of switching to oral feeding. All parameters were significantly greater in patients treated with TORS.

Multilevel Surgery (MLS) and Maxillomandibular Advancement Surgery (MMA)

Moderate to severe OSA is usually characterized by multi-level obstructions, so surgeries aimed at correcting only one region cannot eliminate all obstructions in the upper airway. Multilevel surgery (MLS) and maxillomandibular advancement (MMA) surgery are two well-established treatment options in the surgical management of obstructive sleep apnea (OSA) and target different levels of airway obstruction. Maxillomandibular advancement (MMA) is an invasive yet effective surgical option for obstructive sleep apnea (OSA) that allows the upper airway to be enlarged while physically expanding the facial skeletal structure. The surgery results in the widening of the pharyngeal space by expanding the skeletal structure to which the pharyngeal soft tissues and tongue are attached. This results in reduced pharyngeal collapsibility during negative pressure inspiration. Compared to MLS, MMA can be more effective in improving OSA. However, the complication rate of MMA is higher.

Hypoglossal nerve stimulation (HNS)

Obstructive sleep apnea (OSA) is also characterised by a loss of neuromuscular tone of the dilator muscles of the upper airway. During wakefulness, neuronal activation of the pharyngeal dilator muscles ensures the activation of these muscles, preventing narrowing and pharyngeal collapse.

Why stimulate the hypoglossal nerve?

When activation of the upper airway dilator muscle is lost at the onset of sleep, its ability to keep the airway patent decreases until it collapses. The genioglossus muscle is the most important pharyngeal dilator and has pharyngeal mechanoreceptors and chemoreceptors that transmit the stimulus signals received (carbon dioxide in the blood) to the brainstem, regulating the activity of the upper airway dilator. It has been hypothesized that electrical stimulation of the hypoglossal nerve (HNS), by preventing backward tongue prolapse that causes upper airway obstruction during sleep, could cure obstructive sleep apnea.

How does that work?

The method works by providing, during inhalation, throughout the night, an electrical current to the hypoglossal nerve that determines the contraction of the genioglossus muscle, the main muscle responsible for the stiffening and protrusion of the tongue and all the other intrinsic muscles of the tongue. Unilateral hypoglossal nerve stimulation (HGNS) therapy was approved in 2014 for the treatment of obstructive sleep apnea in middle-aged patients, with a body mass index of less than 32, intolerant to continuous positive airway pressure (CPAP) therapy, which is reported in up to 40-60% of patients.

By what technique?

Currently, with the most widely used technique, the stimulating electrode is placed on the medial branch of the right hypoglossal nerve. Stimulation can be synchronised with breathing using leads that measure changes in breathing. Respiratory detection leads are placed between the external and internal intercostal muscle, and an implantable pulse generator is implanted in the chest wall to activate the hypoglossal nerve electrodes in response to respiratory effort. With the use of this therapy, studies have shown significant reductions in both respiratory parameters such as indices of disordered breathing, and subjective sleep disorders, such as daytime sleepiness, reaching a success rate of 75%, with a reasonable rate of long-term complications.

Are there other techniques?

While HNS represents an invasive treatment for selected patients with moderate to severe OSA, transcutaneous electrical stimulation (TES) of the upper airway is being studied as a non-invasive alternative. However, there are no long-term follow-up data of the transcutaneous approach in the home setting so far. Recently, a new device known as the GENIO system has been developed to provide bilateral hypoglossal nerve stimulation for moderate to severe OSAS, via an implanted and externally activated neurostimulator. Bilateral HNS reduces the severity of OSA with a 45% decrease and improves quality of life without device-related complications. The results are comparable to those of unilateral HNS systems.

Peculiarities of bilateral stimulation

The system offers distinct and potentially beneficial differences.

These include:

• Bilateral HNS instead of unilateral.
  Minimal implanted equipment and battery-free components, with the activation unit worn externally.
  Stimulation delivered at a predetermined, adjustable frequency and duty cycle rather than requiring inspiratory synchronization with the relevant implanted sensing leads.

All these changes act to decrease the complexity and invasiveness of the HNS application and simplify and facilitate the maintenance of the system. Bilateral HNS reduces the severity of OSA and improves quality of life without device-related complications. It differs favourably from previous HNS devices in that it does not require any lead (connecting wires between the sensor/cuff electrodes and the pulse generator) and only one incision is required. In addition, stimulation is delivered bilaterally and controlled by an externally worn unit that activates a small battery-less implanted submental stimulator at a predetermined, adjustable speed and duty cycle.

Pros:

• Surgical treatment with hypoglossal nerve stimulation appears to be effective and well tolerated with lasting benefits.

Contra:

• Is invasive and more expensive than oral braces and CPAP. HNS should not be used as a first-line treatment for patients with OSA in general. The invasiveness of HNS means that it is not easily reversible