Airway Obstruction

Question 1

what determines the diameter of the airway

Answer 1

the cricoid cartilage is the only comlepte cartilaginous ring in the larynx, therefore it does

Question 2

describe 4 special ENT features in children

Answer 2

large head

small nares

relatively large tongue

weak muscles and floppy head

Question 3

how does the larynx differ in neonates

Answer 3

smaller and softer

higher - epiglottis rests at C1 (normally C3) and inferior margin of cricoid cartilage around C4

Question 4

how does the subglottis differ in neonates

Answer 4

narrower - 3.5mm at cricoid

Question 5

how does breathing differ in neonates

Answer 5

they are obligate nasal breathers

Question 6

what is the equation for airflow resistance

Answer 6

AFR (proportional to) (1/r^4)

Question 7

what is the significance of Poiseuille’s equation and Venturi effect in relation to airflow resistance in the airway

Answer 7

a tiny reduction in radius results in a significant increase in resistance and decrease in cross sectional area

this greatly increases the work of breathing

Question 8

what are the consequences of neonates having floppy airways

Answer 8

can collapse and cause stridor or stretor

Question 9

causes of airway obstruction

Answer 9

• Inflammatory/infective/allergy
  
  • Tonsillar and adenoid enlargement
  • Acute epiglottitis
• FB
• Physical compression/invasion of airway
• Trauma
• Neurological
• Neoplastic
• Burn
• Congenital airway pathology

Question 10

signs/symptoms of airway obstruction

Answer 10

hypoxia, exertion related

• SOB on exertion or at rest
• Coughing
• Choking
• Inability to complete sentence
• Sternal/subcostal recession
• Tracheal tug
• Dusky skin colour
• Dysphagia
• Dysphonia
• Pyrexia
• Cyanosis

Question 11

stridor

Answer 11

high pitched harsh noise due to turbulent airflow resulting from airway obstructions

Question 12

stertor

Answer 12

low pitched sonorous sound arising from nasopharyngeal airway (heaving snoring/gasping)

Question 13

recurrent respiratory papillomatosis

Answer 13

warty growths in the upper airway causing significant airway obstruction or voice change

Question 14

aetiology of recurrent respiratory papillomatosis

Answer 14

caused by HPV, types 6 and 11 cause the majority of cases, and 16 and 18 have also been implicated

Question 15

management of recurrent respiratory papillomatosis

Answer 15

extremely serious as it has the potential to destroy the whole of the larynx

extensive surgical management is required

Question 16

age distribution of recurrent respiratory papillomatosis

Answer 16

bimodal - juvenile <12 and adult onset around the age of 40

Question 17

subglottic stenosis

Answer 17

partial or complete narrowing of the subglottic area

Question 18

aetiology of subglottic stenosis

Answer 18

rarely congenital

90% of cases are caused by endotracheal intubation - the duration of intubation is the most important factor in the development of stenosis

small vessel vasculitis

gastric acid reflux

Question 19

how can small vessel vasculitis cause subglottic stenosis

Answer 19

can cause tracheal tissue damage and scarring

Question 20

in which patients does gastric acid reflux cause subglottic stenosis

Answer 20

extremely overweight patients

Question 21

ASSESSMENT of airway obstruction

Answer 21

appearance, skin circulation, work of breathing

Question 22

ideally, how is respiratory failure managed

Answer 22

there is a progression from respiratory distress, to failure to arrest within a matter of minutes. The aim is to intervene before the development of respiratory distress

Question 23

heliox

Answer 23

helium and oxygen

helium has a lower density than air, this means that there is a reduction in resistance to flow in airways and reduction in work of breathing

Question 24

management of respiratory distress

Answer 24

ABCDE

oxygen, heliox

steroid

adrenaline

flexible fibre-optic endoscopy

secure airway with ET tube/tracheostomy

Question 25

when should tracheostomy be performed

Answer 25

avoided at all possibilities as there is a significant risk of morbidity and mortality