Respiratory Flashcards
What are the volumes and capacities of the lungs?
- 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).
What percentage of the alveolar epithelial surface is made up by Type I pneumocytes?
- 95%
- 5% Type II but they make up 60% of the cells in the alveoli.
What is the purpose of Type II pneumocytes?
- 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.
Where do pulmonary alveolar macrophages originate?
- The bone marrow.
What is the function of pulmonary alveolar macrophages?
- 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.
At what level of the spinal cord do the phrenic nerves originate and what are the implications of this?
- 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.
What percentage of tracheoesophageal fistulas are related to a syndrome?
- 50%
What is the most common form of TOF?
- C type (87%).
- Upper oesophagus terminates in a blind pouch.
TOF originates from distal oesophagus.
What is the most common oesophageal anomaly in children?
- Oesophageal atresia (1.7/10,000)
- 90% associated with TOF.
What syndrome is most frequently associated with TOF?
- VATER/VACTERL (vertebral, anorectal, cardiac, tracheal, oesophageal, renal, limb).
In what percentage of children with syndrome associated TOF are cardiac and vertebral anomalies seen?
- 32% and 24% respectively.
What are the most common complications following TOF repair?
- Usually in first 5y post-repair.
- Anastomotic stricture, refistulisation, anastomotic leak.
What features of TOF repair contribute to increased complication rate?
- GORD is common and increases frequency of anastomotic stricture.
- Also worsens reactive airways disease seen in GORD.
What intrathoracic malignancy most often causes chylothorax?
- Lymphoma.
In newborns what causes chylothorax?
- Rapid increase in venous pressure during delivery leads to rupture of the thoracic duct.
What laboratory findings confirm chylothorax?
- 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.
What are complications of chylothorax?
- 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.
What are the predominant fats found in chyle?
- Triglycerides in chylomicron form.
- Esterified long chain fatty acids.
What is the treatment of chylothorax?
- 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.
What is the alveolar air equation?
- PAO2 = (baro P - PH2O) X FiO2 - (PCO2 x 1/R)
How is surfactant homeostasis maintained in the alveoli?
- Balanced production of surfactant by type II alveolar cells clearance by uptake and catabolism in alveolar macrophages.
What is PU.1 transcription factor?
- Nuclear transcription factor involved in the regulation of alveolar macrophage maturation.
- Reduction in PU.1 leads to impaired alveolar macrophage function.
What is pulmonary alveolar proteinosis?
- 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.
What are the 5 phases of lung development?
- Embryonic (26d-6w).
- Pseudoglandular (6-16w)
- Canalicular (16-28w).
- Saccular (28-36w).
- Alveolar (36w- infancy).
What is the triad seen in Kartagener syndrome?
- Bronchiectasis, chronic sinusitis, situs inversus.
What is the treatment for Aspergillus found on BAL?
- 1m itraconazole.
What is the treatment for allergic bronchopulmonary aspergillosis?
- Oral steroids for 2 weeks and then wean slowly.
- Oral itraconazole - stop 1m after finishing steroids.
What are the typical blood findings of undiagnosed CF?
- Hyponatraemic, hypochloraemic alkalosis.
