Anatomy of upper airway

Question 1

How does anatomy of upper airway change in sleep?

Answer 1

How this changes in sleep?

• Soft palate to the larynx is know as the pharyngeal region,
• Pharyngeal narrowing and increased resistance to flow
• Genioglossus (Large muscle at the base of the tongue) is the most important pharyngeal dilator muscle

Question 2

Components of the upper airway?

Answer 2

Nasopharynx
Oropharynx
Hypopharynx
Larynx

Lower airway - tracheobronchial tree

Question 3

Neuromodulators, such as serotonin, norepinephrine, glutamate, thyrotropin-releasing hormone, and substance P have a key role in the activity of upper airway muscles. These may become compromised in the presence of obstructive sleep apnoea, which may be also affected by intermittent hypoxia that occurs, and further enhanced effects in the presence of intermittent severe hypoxia. Where stimulation of peripheral chemoreceptors occurs by the presence of intermittent hypoxia, a prolonged rise in minute ventilation with a decrease in upper airway resistance can occur.

Question 4

Abnormal anatomy

Answer 4

Macroglossia (enlarged tongue) is a rare condition that typically affects more children than adults. People with macroglossia have tongues that are larger than typical, given the size of their mouths.

Hyoid position

Adenotonsillar hypertrophy

Maxillary/ mandibular hypoplasic or retroposition

Thickening of lateral pharyngeal walls
- increased vascular tone
-increased ,muscle volume
- inflammation/ edema in pharyngeal

Question 5

What is the Mallampati score?

Answer 5

The Mallampati score is one assessment to describe the relative size of the base of the tongue compared to the oropharyngeal opening in hopes of predicting the difficult airway.

Related to the presence and severity of OSA. For each 1-point increase, the odd ratio of having OSAS increased by 2.5x and AHI by >5.2 events/hr

Question 6

Mandibular deficiency forms

Answer 6

• open bite which leaves a space between upper and lower teeth when mouth is closed
• prognathic jaw occurs when lower jaw is overdeveloped and protrudes beyond upper jaw
• retrognathia is a receding lower jaw/ weak chin

Jaw position (left images) will affect upper airway diameter with the retrognathic jaw significantly reducing airway diameter, thereby making it more likely that there will be apnoeas occurring. Surgery, where appropriate, could reduce these issues.

Question 7

What is acromegaly?

Answer 7

A condition where the body produces too much growth hormone leading to excess growth of body tissues over time

Acromegaly is a hormonal disorder caused by a non cancerous tumour in the pituitary gland.
*This in turn causes excess production of growth hormone after epiphyseal plate closure at puberty.
*A person with acromegaly usually has large hands and feet, thick lips and large tongue, a jutting forehead and jaw, and widely spaced teeth.
Periodic obstruction during sleep occurs because the large tongue bulges into the pharynx obliterating the pharyngeal airway.

Question 8

Enlarged tonsils/ adenoids

Answer 8

In pads, tonsillectomy is a common treatment for OSA
In adults refer to ENT to remove obstruction if prominent

Question 9

Fat deposition

Answer 9

Patients with enlarged tongues and excess fat deposition are more likely to have slept apnoea

Question 10

Features of an apnoeic airway

Answer 10

• narrowed airway size
• excess fat deposition in chin and neck
• retrognathic mandible
• drip laced and large tongue
  -reduced intranasal space
• reduced retropalatal space
• excess fat at pharyngeal wall
• enlarged and lengthened soft palate
• reduced/ narrowed retroglossal space