Respiratory

Question 1

What are the volumes and capacities of the lungs?

Answer 1

• 4 volumes and 4 capacities.
• Volumes do not overlap, capacities do.
• Capacities are made up of different combinations of lung volumes.
• Volumes:
• -> tidal volume: amount of air moved in and out of lung during each breath.
• -> expiratory reserve volume: amount exhaled with maximal effort after tidal expiration.
• -> inspiratory reserve volume: amount inhaled with maximal effort following tidal inspiration.
• -> residual volume: volume of gas remaining in the lungs after maximum expiration.
• Capacities:
• -> inspiratory capacity: amount inspired by maximum effort following tidal expiration (tidal volume + inspiratory reserve volume).
• -> functional residual capacity: amount of gas in lungs following tidal expiration (expiratory reserve volume + residual volume).
• -> Vital capacity: amount of gas moved with max inspiratory and expiratory effort (inspiratory reserve volume + tidal volume + expiratory reserve volume).
• ->Total lung capacity: volume of gas occupying lungs after max inspiration (inspiratory reserve volume + tidal volume + expiratory reserve volume + residual volume).

Question 2

What percentage of the alveolar epithelial surface is made up by Type I pneumocytes?

Answer 2

• 95%

- 5% Type II but they make up 60% of the cells in the alveoli.

Question 3

What is the purpose of Type II pneumocytes?

Answer 3

• Lamella bodies are formed containing phospholipids.
• Lamella bodies secreted to the alveolar lumen by exocytosis.
• Myelin tubules form and create a phospholipid film.
• Hydrophobic tails face the alveolar lumen.

Question 4

Where do pulmonary alveolar macrophages originate?

Answer 4

• The bone marrow.

Question 5

What is the function of pulmonary alveolar macrophages?

Answer 5

• Ingest small particles that evade the mucocillary elevator.
• Process inhaled allergens for immunologic attack.
• Secrete substances that stimulate granulocyte and monocyte formation in the bone marrow.

Question 6

At what level of the spinal cord do the phrenic nerves originate and what are the implications of this?

Answer 6

• C3-C5.
• Transection of the spinal cord above C3 is fatal without mechanical ventilation.
• Transection of the cord below C5 is not as the phrenic nerve remains intact and thus the diaphragm is functional.

Question 7

What percentage of tracheoesophageal fistulas are related to a syndrome?

Answer 7

• 50%

Question 8

What is the most common form of TOF?

Answer 8

• C type (87%).
• Upper oesophagus terminates in a blind pouch.
  TOF originates from distal oesophagus.

Question 9

What is the most common oesophageal anomaly in children?

Answer 9

• Oesophageal atresia (1.7/10,000)

- 90% associated with TOF.

Question 10

What syndrome is most frequently associated with TOF?

Answer 10

• VATER/VACTERL (vertebral, anorectal, cardiac, tracheal, oesophageal, renal, limb).

Question 11

In what percentage of children with syndrome associated TOF are cardiac and vertebral anomalies seen?

Answer 11

• 32% and 24% respectively.

Question 12

What are the most common complications following TOF repair?

Answer 12

• Usually in first 5y post-repair.

- Anastomotic stricture, refistulisation, anastomotic leak.

Question 13

What features of TOF repair contribute to increased complication rate?

Answer 13

• GORD is common and increases frequency of anastomotic stricture.
• Also worsens reactive airways disease seen in GORD.

Question 14

What intrathoracic malignancy most often causes chylothorax?

Answer 14

• Lymphoma.

Question 15

In newborns what causes chylothorax?

Answer 15

• Rapid increase in venous pressure during delivery leads to rupture of the thoracic duct.

Question 16

What laboratory findings confirm chylothorax?

Answer 16

• Fluid TG level >1.24mmol/L, pleural fluid: serum TG level >1.0 with cholesterol < 5.18mmol/L.
• Chylomicrons are present on analysis.
• Elevated fluid T-lymphocytes.

Question 17

What are complications of chylothorax?

Answer 17

• Malnutrition (calories, protein and electrolyte loss).
• Hypogammaglobulinaemia and impaired cell mediated immunity.
• Loss of T lymphocytes can cause infection in neonates.
• Avoid live virus vaccines.

Question 18

What are the predominant fats found in chyle?

Answer 18

• Triglycerides in chylomicron form.

- Esterified long chain fatty acids.

Question 19

What is the treatment of chylothorax?

Answer 19

• Enteral feeds with high protein with low fat or medium chain triglycerides.
• PRN thoracentesis.
• TPN if no improvement 1-2/52.
• If ongoing consider: pleuroperitoneal shunt, thoracic duct ligation, fibrin glue.
• Neonates with output >50ml/kg/d on maximal therapy 3/7 - consider surgery.

Question 20

What is the alveolar air equation?

Answer 20

• PAO2 = (baro P - PH2O) X FiO2 - (PCO2 x 1/R)

Question 21

How is surfactant homeostasis maintained in the alveoli?

Answer 21

• Balanced production of surfactant by type II alveolar cells clearance by uptake and catabolism in alveolar macrophages.

Question 22

What is PU.1 transcription factor?

Answer 22

• Nuclear transcription factor involved in the regulation of alveolar macrophage maturation.
• Reduction in PU.1 leads to impaired alveolar macrophage function.

Question 23

What is pulmonary alveolar proteinosis?

Answer 23

• Rare.
• Progressive accumulation of surfactant due to insufficient clearance.
• Believed to be due to accumulation of surfactant that is produced normally but is unable to be catabolised and cleared by macrophages.
• Deficiency in PU.1 as well as neutralising antibodies or mutations or deficiency of GM-CSF.

Question 24

What are the 5 phases of lung development?

Answer 24

• Embryonic (26d-6w).
• Pseudoglandular (6-16w)
• Canalicular (16-28w).
• Saccular (28-36w).
• Alveolar (36w- infancy).

Question 25

What is the triad seen in Kartagener syndrome?

Answer 25

• Bronchiectasis, chronic sinusitis, situs inversus.

Question 26

What is the treatment for Aspergillus found on BAL?

Answer 26

• 1m itraconazole.

Question 27

What is the treatment for allergic bronchopulmonary aspergillosis?

Answer 27

• Oral steroids for 2 weeks and then wean slowly.

- Oral itraconazole - stop 1m after finishing steroids.

Question 28

What are the typical blood findings of undiagnosed CF?

Answer 28

• Hyponatraemic, hypochloraemic alkalosis.