Written by Siyanda Rich Shinga (BHSc in Clinical Technology: Neurophysiology)

Sleep is an important and naturally recurring state of mind and body characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement sleep. Sleep-Related Breathing Disorder (SRBD) are disorders in which abnormalities in breathing occur during sleep that may or may not be present while awake. The different types sleep-related breathing disorders include central sleep apnea, Obstructive sleep apnea, mixed sleep apnea, upper air-way resistance syndrome and sleep-related hypoventilation/hypoxaemia.

Types of sleep related breathing disorders

1. Central sleep apnea– defined by episodes of not breathing during which there is no indication of an effort to breathe in the signals that are recorded in a sleep study
   • This is due to increased sensitivity to the respiratory centre to pCO2, producing relative hypocapnia and prolonged circulation time.
2. Obstructive sleep apnea– defined by continued effort to breathe but an obstructed upper air way. Patients with this disorder present with symptoms such as severe snoring, wakes up gasping for air during sleep, persistence fatigue and low sex drive.
3. Mixed sleep apnea– usually starts with central sleep apnea and develops into obstructive sleep apnea later.
4. Upper airway resistance syndrome– is accompanied by subjective and objective evidence of pathologic sleepiness. In some individuals, even a minor reduction of airway patency with sleep onset may lead to a modest increase in upper airway resistance and a slight decrease of tidal volume without hypoxemia.
5. Sleep related Hypoventilation/Hypoxemia– hypoventilation refers to reduction of the amount of air flow and hypoxemia refers to a low oxygen level. Hypoventilation and hypoxemia may occur due to:
   • Impaired gas exchange between the alveoli and blood
   • Failure of inhaled air to reach the lungs
   • Failure of the lungs to properly inflate

Diagnosis of SRBD

• Central sleep apnea- sleep study Polysomnogram (PSG)
• Ostructive Sleep Apnea- sleep study PSG
• Sleep relatated hypoventilation/hypoxeamia

In the evaluation of sleep apnea patients suspected of having sleep apnea syndromes the following is essential:

• Sleep history – both from patient and sleep partner
• Physical examination should include:
  1. Blood pressure
  2. Evidence of right sided heart failure
  3. Abnormal skeletal and muscle configurations of the face and neck
  4. Chest radiographs and electrocardiograms are essential in evaluating pulmonary hypertension, status of right and left ventricle and establishing possible coexistence of cardiopulmonary disease.
  5. A complete blood count- assists in documenting the presence of polycythemia in chronic hypoxeamia or right sided heart failure
  6. Pulmonary function studies with arterial blood gas sampling- may be necessary to determine airway obstruction or investigate primary hypoventilation during waking state and document hypoventilation and hypercapnia.
  7. Polysomnogram- which is necessary for the estimation of the severity of the sleep disordered breathing, sleep fragmentations and oxyhaemoglobin desaturations
     • The severity is determined by the Apnea-Hypopnea Index- that is the number of episodes per hour of sleep

Treatment of SRBD

Treatment of SRBD includes the following:

1. Behavioural interventions

• Weight loss
• Avoidance of alcohol and sedatives
• Avoidance of supine sleep position
• Discontinuation of smoking

2. Continuous positive airway pressure treatments

• Nasal or oral positive airway pressure (NCPAP or OPAP)
• Bilevel positive airway pressure (BPAP)
• Auto-adjusting positive airway pressure (Auto-PAP)

3. Surgical procedures

• Bypass surgery
• Tracheostomy

4. Upper airway reconstructions

• Soft-tissue modifications (Uvulopalatopharyngoplasty [UPPP], laser-assisted UPPP [LAUP], somnoplasty, radiofrequency volumetric reduction of the tongue, laser lingual resection—lingualplasty, tongue base suspension, tonsillectomy)

5. Skeletal modifications

• Mandibular osteotomy with genioglossal advancement and hyoid suspension, maxillomandibular osteotomy and advancement, hyoid myotomy and suspension to mandible, hyoid myotomy and suspension to thyroid cartilage, anterior hyoid advancement, transpalatal advancement pharyngoplasty, nasal surgery

6. Pharmacologic agents

• Medroxyprogesterone, decongestants, nasal steroids, antihistamines, protryptiline, and serotonergic agents: fluoxetine and other selective serotonin reuptake inhibitors, L-tryptophane

Tel: 074 700 0062
E-mail: neurophysiology245@gmail.com
Address: Suite 2, Connor-Med Health Centre, 20 Connor St, Port Shepstone, 4240

References

• Neurology for the Non-Neurologist
• A technologist’s introduction to sleep disorders (AASM)
• Polysomnography in Patients With Obstructive Sleep Apnea (PubMed) Accessed(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3379160/pdf/ohtas-06-38a.pdf)
• PSG in the Diagnosis of Central Sleep Apnea (Medscape) Accessed: (https://www.medscape.com/answers/304967-114297/what-is-the-role-of-polysomnography-in-the-diagnosis-of-central-sleep-apnea-csa)

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