Sleep Apnoea/Hypopnoea

It is when the muscles in the throat relax and/or fat deposits in the neck causing a blockage in the airways and interrupting ones breathing or airflow during sleep for longer than 10 seconds per episode and is known as apnoea.

• It also may occur due to a depressed signal from the brainstem to initiate a breath.
• If the airways passages are partially blocked (more than 50%) for longer than 10 seconds per episode it is known as hypopnea.
• It can lead to snoring and/or sleep groaning.
• When this occurs the body wakes you up from your deep sleep to open the airways affecting your sleep at night.

Diagnosis Tests

Physical examination

Physical examination findings may include the following:

• Obesity: body mass index > 30 kg/m²
• Large neck circumference: > 17 inches (43 cm) in men and > 15 inches (37 cm) in women
• Abnormal (increased) Mallampati score (a subjective evaluation of the ratio of oral cavity volume to tongue volume)
• Narrowing of the lateral airway walls: an independent predictor of the presence of obstructive sleep apnoea in men but not women
• Enlarged tonsils
• Retrognathia or micrognathia:
  • Retrognathia is a condition where the lower jaw is set back further compared to the upper jaw. It gives patients the appearance of a severe overbite. The difference in placement between the lower and upper jaw is not often noticeable when looking head on, but is more obvious when viewing the person from the side or profile view)
  • Micrognathia is a condition in which the lower jaw is undersized.
• Large degree of overjet
• High-arched hard palate
• Systemic arterial hypertension
• Congestive heart failure
• Pulmonary hypertension
• Stroke
• Type 2 Diabetes mellitus
• Metabolic syndrome

Medscape

The following findings on polysomnography are characteristic of Obstructive Sleep Aponea:

• Apnoeic episodes occur in the presence of respiratory muscle effort.
• Apnoeic episodes lasting 10 seconds or longer are considered clinically significant.
• Apnoeic episodes are most prevalent during REM sleep. In some patients, they may occur exclusively during REM sleep.
• Patients may have a combination of apnoea’s and hypopneas, or they may have one or the other exclusively.
• Mixed aponeas may occur.
• Sleep disruption due to arousals is usually seen at the termination of an episode of apnoea.

OSA is diagnosed by calculating the aponea-hypopnea index, which represents the hourly average of aponeic episodes associated with hypoxemia during sleep.

• The index is considered positive if there are more than 14 events per hour in an asymptomatic patient and more than four events per hour in a symptomatic patient

Qaseem A, Dallas P, Owens DK, Starkey M, Holty JE, Shekelle P, Clinical Guidelines Committee of the American College of Physicians. Diagnosis of obstructive sleep apnea in adults: a clinical practice guideline from the American College of Physicians. Ann Intern Med. 2014;161:210-220. Source

Berry RB, Budhiraja R, Gottlieb DJ, et al; American Academy of Sleep Medicine. Rules for scoring respiratory events in sleep: update of the 2007 AASM Manual for the Scoring of Sleep and Associated Events. Deliberations of the Sleep Apnea Definitions Task Force of the American Academy of Sleep Medicine. J Clin Sleep Med. 2012;8:597-619

Medscape

Oxygen Saturation test (via Oxygen level meter)

• Oxygen saturation (SpO₂) is an important diagnostic tool and measures the amount of haemoglobin-bound oxygen and free oxygen.
• The partial pressure of arterial O₂ (PaO₂) is measured by arterial blood gas monitoring. In healthy individuals, SpO₂ is usually >95%.
• In patients with chronic lung disease or sleep apnoea, SpO₂ can range between 88–92%.

McNicholas W, Kent, Mitchell. Hypoxemia in patients with COPD: cause, effects, and disease progression. COPD 2011;:199. doi:10.2147/copd.s10611

Other diagnosis measures (questionaries) i.e.

• STOP-Bang questionnaire  (snoring, tiredness, observed aponea, high blood pressure, BMI, age, neck circumference, and male gender)
• Epworth Sleepiness Scale