Obstructive Sleep Apnoea Flashcards
For obstructive sleep apnoea,
- Define
- State what it is caused by
- State its features
Definition:
• No airflow/oxygen for more than 10 seconds during sleeping. This causes oxygen desaturation from red blood cells (anything less than 10 seconds is not concerning)
Caused by:
• Occurs due to partial or complete blockage of the airway
Features:
• There is still apnoea diaphragm activity and/or thoraco-abdominal wall movement (may be more increased)
• Paradoxical thoraco-abdominal movement may occur: diaphragm moves opposite to the normal directions of its movements (normally moves downwards during inspiration and upwards during expiration)
• Snoring is a normal clinical feature
For central apnoea
- Define it
- State what it is caused by
- Differentiate it from obstructive sleep apnoea
Definition:
• Lack of respiratory effort during periods of no airflow
• No diaphragm activity and/or thoraco-abdominal wall movement
Caused by:
• Occurs because the CNS temporarily fails to drive the muscles responsible for controlling breathing
Differentiation:
• Different from obstructive sleepapnoea which occurs due to upper airway obstruction
• Loud snoring is uncommon
Define mixed apnoea
Apnoea with both central and obstructive components, with central component for at least one respiratory cycle length
Identify the 9 signs/symptoms obstructive sleep apnoea
- Snoring
- Episodes of gasping, snorting or choking during sleep
- Excessive daytime sleepiness
- Fatigue, lack of energy
- Poor memory and concentration
- Morning headaches
- Dry mouth or sore throat upon waking
- Irritability, depression, anxiety, mood and behaviour changes
- Rapid weight gain (endocrine changes)
List the 10 risk factors for obstructive sleep apnoea
- Sex: males (higher pharyngeal resistance)
- Age (pharyngeal resistance increases, other risks increase)
- Obesity (fat deposition)
- Large neck circumference
- Genetics/ FHx
- Craniofacial anatomy (retrognathia/retruded mandible, micrognathia/ small jaw, enlarged tonsils, nasal obstruction)
- Cigarette smoking (nasal obstruction via tartar deposition)
- Excessive alcohol consumption (reduced muscle tone)
- Medications such as sedatives
- Infiltration of muscles and soft tissues (myxoedema, acromegaly, neoplastic processes, mucopolysaccharidosis)
List the 3 diagnostic criteria for obstructive sleep apnoea
A.
Excessive daytime sleepiness unexplained by other factors
B. Two or more of the following symptoms: • Choking during sleep • Recurrent nocturnal awakening • Unrefreshing sleep • Daytime fatigue • Impaired concentration
C.
Overnight monitoring demonstrates 5 or more apnoeas plus hyponoeas per hour of sleep
Must fulfil A or B PLUS C
Describe the sites implicated in obstructive sleep apnoea
- Musclesin the back of the throat relax too much to allow normal breathing
- This region starts from the choanae (back of nose) and goes to the epiglottis
- Muscleswithin this region include support structures like the soft palate, uvula, the tonsils and the tongue
Explain the possible anatomical causes of obstructive sleep apnoea (5)
The nasopharyngeal and oropharyngeal segment of the upper airway is a hollow muscular tube. Airway patency depends on a balance of collapsing and dilating forces.
- Anatomical narrowing of the pharyngeal airway (inflammation or anatomical variations)
- Excessive loss of upper airway muscle tone (binge drinking)
- Defective upper airway protective reflexes
- Increased loop gain promotes an unstable airway
- Frequent arousals destabilise airway
Explain the pathophysiology of obstructive sleep apnoea
- During OSA, there is increase breathing effort as oxygen saturation decreases. Decreased oxygen leads to increases in carbon dioxide levels, and thus pH
- The patient is made to wake up as the upper away muscles increases their activity and reopen. The patient hyperventilates
- This increases oxygen concentration and decreases carbon dioxide levels, thus the patient returns to sleep
- As they sleep, the upper airway muscles increase in resistance with decreased upper airway muscle dilation and decreases lung volume
- Thus, the patient hypoventilates and eventually falls back into the cycle of OSA
Describe the chemoreceptor reflex in respiratory control in obstructive sleep apnoea
- Chemoreceptors exist in the CNS and the PNS (heart)
- The CNS chemoreceptors usually detect pH levels of blood, whereas the PNS detect O2 and Co2 concentrations (NOT pH).
- Signals are sent respiratory centres of the brain to adjust the ventilation rate to change acidity and/or O2 or Co2 concentrations
- During sleep apnoea, there is increased Co2 levels and increased acidity
- Thus, messages from the CNS chemoreceptors are sent to the medullary respiratory centres, which informs respiratory muscles to increases exhalation
- This lowers arterial PC02 and returns pH to normal levels
Discuss obstructive sleep apnoea in children, and its potential causes (5)
• Snoring is common in children, but OSA is not common in children
Causes include: • Commonly enlargement of the tonsils and adenoids • Obesity • Long-term allergy or hay fever • Medications • Craniofacial anatomy
Explain why apnoea does not happen during the day, and is more common during sleep
- During wakefulness, there is an increased reflex response to negative airway pressure. This helps increase pharyngeal dilator muscle activity
- However, this is lost during sleep
Discuss the 3 major consequences of obstructive sleep apnoea
Decreased oxyhaemoglobin saturation can lead to:
• Pulmonary and systemic hypertension
• Cardiac arrhythmias
• Myocardial infarction and stroke
Fragmented sleep due to repeated arousals required to reopen airway and resume breathing: • Insomnia • Cognitive dysfunction • Memory loss • Emotional disturbances • Social disharmony
Obesity:
• Rapid weight gain should be a trigger to look for symptoms of OSA
• Also lead to increased risk for cardiovascular disease, stroke, and atrial fibrillation, as well as diabetes and insulin resistance
List the general treatment options (3) and the dental treatment options (4) for obstructive sleep apnoea
General options:
• Continuous positive airway pressure CPAP
• Lifestyle change
• Surgical options (tonsillectomy, adenoidectomy)
Dental treatment options: • Maxillo-mandibular advancement MMA • Genioglossus advancement GA • Mandibular advancement splints MAS or Mandibular repositioning device MRD • New innovative device - O2vent
