Understanding Obstructive Sleep Apnoea (OSA)

Written By Activa Media

What is obstructive sleep apnoea (OSA)?

Obstructive sleep apnoea (OSA) is a sleep disorder characterized by cessation of breathing during sleep. These episodes, known as apnoeas, can last for several seconds and occur multiple times per hour, leading to fragmented and poor-quality sleep.

Apnoea, as defined by the American Academy of Sleep Medicine (AASM): ≥ 90% reduction in airflow for ≥ 10 seconds

Hypopnoea: ≥ 30% drop in airflow for ≥ 10 seconds associated with an arousal or a ≥ 3% oxygen desaturation.

What is Apnoea-Hypopnea Index (AHI)?

The AHI is a key metric used to diagnose and classify the severity of sleep apnoea.  AHI is defined as the number of apnoeas and hypopneas per hour of sleep.

OSA Severity Classification for adults

  • Normal: AHI < 5 events per hour

  • Mild OSA: AHI 5-14 events per hour

  • Moderate OSA: AHI 15-29 events per hour

  • Severe OSA: AHI ≥ 30 events per hour

What are the primary symptoms of sleep apnoea?

The primary symptoms of sleep apnoea include:

  • Loud snoring

  • Episodes of breathing cessation

  • Gasping or choking during sleep with awakenings

  • Excessive daytime sleepiness

  • Morning headaches

  • Difficulty concentrating at work or school

  • Mood changes such as irritability and depression

What are the common risk factors for developing sleep apnoea?

The risk factors for sleep apnoea include:

  • Obesity

  • Increased neck circumference

  • Older age

  • Male gender

  • Family history

  • Alcohol and smoking

What is the STOP-BANG questionnaire?

The STOP-BANG questionnaire is a screening tool used to assess a patient's risk for OSA.

It consists of eight yes/no questions, where each letter in "STOP-BANG" represents a question related to potential risk factors for OSA:

  1. S - Snoring: Do you snore loudly (louder than talking or loud enough to be heard through closed doors)?

  2. T - Tiredness: Do you often feel tired, fatigued, or sleepy during the daytime?

  3. O - Observed: Has anyone observed you stop breathing during your sleep?

  4. P - Blood Pressure: Do you have or are you being treated for high blood pressure?

  5. B - BMI (Body Mass Index): Is your BMI more than 35 kg/m²?

  6. A - Age: Are you older than 50 years old?

  7. N - Neck circumference: Is your neck circumference greater than 40 cm (16 inches) if you are male, or greater than 35 cm (14 inches) if you are female?

  8. G - Gender: Are you male?

Each "yes" answer is given one point, and the total score (ranging from 0 to 8) helps healthcare providers determine the likelihood that an individual has obstructive sleep apnea. A higher score indicates a higher risk, and should be referred to a specialist for OSA evaluation.

The sensitivity of STOP-Bang score ≥ 3 to detect moderate to severe OSA and severe OSA is 93% and 100%, respectively.

What are the health risks associated with untreated sleep apnoea?

Untreated sleep apnoea can lead to a range of serious health issues, including:

  • Cardiovascular complications: Hypertension, myocardial infarctions, heart failure, arrhythmias and cerebrovascular accidents. This is related to OSA-induced changes in endothelial dysfunction, oxidative stress, and systemic inflammation.

  • Type 2 Diabetes: Insulin resistance and glucose intolerance can be exacerbated by OSA.

  • Metabolic syndrome

  • Hepatic complications: Nonalcoholic fatty liver disease and liver function impairment.

  • Daytime fatigue and accidents: Increased risk of motor vehicle accidents and workplace injuries due to excessive daytime sleepiness.

  • Mental health issues: Depression, anxiety, and cognitive impairment. Several studies have indicated that in some fields of cognitive functions, the deficits caused by untreated OSA can be irreversible, and show only partial recovery after a period of treatment with CPAP.

What are the treatment strategies for managing sleep apnoea?

Treatment options for sleep apnoea include:

  • Lifestyle changes: Weight loss, regular exercise, avoiding alcohol and sedatives, and sleeping on the side rather than supine (for those with positional OSA).

  • Continuous positive airway pressure (CPAP) ventilation: A CPAP device is often the first line treatment measure for OSA; however, compliance is variable.  Meta-analyses and systematic reviews have reported overall adherence rates to CPAP therapy ranging from 46% to 60%.

  • Oral appliances: Custom-fitted devices, such as mandibular advancement devices or tongue-stabilizing devices, that reposition the jaw or tongue can be used in mild to moderate OSA.

  • Surgery: Multilevel surgery addressing the anatomical airway obstruction is usually considered when the patient is not able to tolerate CPAP or oral appliances.   Surgical options include:

  • Nose: Septoplasty, inferior turbinoplasty

  • Palate: Uvulopalatoplasty, repositioning/expansion pharyngoplasty

  • Tongue base reduction

  • Hypoglossal nerve stimulation: Stimulation of the hypoglossal nerve results in advancement of the tongue and hence expansion of the airway during sleep.

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