Lungs Flashcards
At what vertebral level is the carina?
T4 and T5 (2nd rib)
Where would a chest drain be placed?
5th intercostal space, above rib, MAL
What is the transit time of a RBC in the capillaries of the lungs?
0.75s
A reduced FEV1/FCV ratio with a normal FVC signifies what?
Obstructive disease of the lungs
What is a normal FEV1/FVC ratio?
Between 75% and 80%
A normal FEV1/FVC ratio with a dramatically reduced FVS signifies what?
Restrictive disease of lungs
What is bronchiectasis?
Abnormally widened lumen of the airways which accumulate excess mucous -> these make the lungs vulnerable to infections
Which cells of the lungs produce surfactant?
Type II pneumocytes
What is Fick’s law of diffusion?
The amount of gas that moves across a membrane is proportional to the area and inversly proportional to the thickness
Which portion of the lungs are better ventilated?
Bases
What is the mean pressure in the pulmonary artery?
15mmHg
What is the mean pressure in the aorta?
100mmHg
Name 2 mechanisms which cause reduction in pulmonary vascular resistance (in response to slight rise in pressure)
Recruitment and distension
When is the pulmonary vascular resistance at its lowest?
On deep inspiration - expansion of the vessels by the lung parenchyma
Which part of the lungs have the lowest vascular resistance?
Base
What is the Windkessel effect?
Elastic expansion of the large elastic arteries in systole - maintains constant pressure for perfusion of the organs during diastole
What is cor pulmonale?
Enlargement and failure of the right ventricle of the heart as a response to increased vascular resistance or high blood pressure in the lungs
Name 2 SABAs
Salbutamol Terbutaline
Name a drug which is a ß2 agonist and acts on the bronchioles. Name a long term SE of this drug
Salbutamol.
Causes tremor due to its affect on the muscles, hypokalaemia when it acts on the cell membrane
What class of drug is ipratripium? Explain its MOA and SEs
Muscarinic receptor antagonist –> competes with ACh at the muscarinic receptors to prevent bronchoconstriction SE: dry mouth, blurred vision, GIT disturbances
Which receptors does tiotropium act on specifically?
M3 receptors
Which bond in the mucous do mucolytics break?
Disulphide bonds - makes the mucous viscous
What is α1-antitrypsin?
Glycoprotein produced by the liver. It’s a serine protease inhibitor - balances the action of e.g. neutrophil elastase which is present in inflammation
Where is the respiratory centre found?
In the medulla and pons
Name some signs of a ‘blue bloater’
- Bounding pulse
- CO2 flap
- Cyanosis
- Increased JVP
- Ankle swelling
- Tricuspid regurge
Which lobes are damaged in α1-antitrypsin deficiency?
Lower lobes
What is Hamman’s sign?
Mediastinal crunch precordially associated with cardiac systole - cardiac contraction forcing air through the pleural folds
What is Hippocratic succussion?
Sound of splashing in the chest which is sometimes audible without a stethoscope - signifies a very large pleural effusion
What would cause a young, tall, healthy male to have a pneumothorax?
Congenital pleural bleb
Where would a thoracocentesis be sited?
2nd ICS mid clavicular line on the affected side. Converts a tensiion PnTx int o a simple PnTx with a 14g venflon.
What would you suspect as the cause of a transudate pleural effusion?
- HF
- Liver failure
- Renal failure
Name the causes of exudate pleural effusion
(6 listed)
- Neoplastic
- Infection
- Inflammation
- Post-op
- Trauma
- PE
What would cause a stony-dull percussion in the lung?
Pleural effusion
What happens in weeks 3-5 (embryonic stages) of lung development?
Lung bud is forming from the ventral wall of the foregut derived from endoderm. Also starts to branch.
What happens in weeks 6-16 (pseudoglandular stages) of lung development?
Branching
Name the embryonic stage of lung development which from 25weelk - term.
Saccular
What is happening in the saccular stages of lung development?
- increase in the number and size od alveoli
- increase in type I and type II pneumocytes
- increase in surface area
What is the biggest limiting factore for premature ex-utero survival?
Surface area of the lungs
(lack of perfusion and lack of surfactant also factors)
What is respiratory distress syndrome?
Lack of surfactant causing atelectasis
What is the Tx for respiratory distress syndrome?
IV fluids
CPAP with O2
Name 3 things which enable the binding of the 4 polypeptide chains of Hb
- salt bridges
- H bonds
- hydrophobic effect
What is the role of 2,3 DBG in Hb?
Interacts with the ß subunits of the Hb decreasing their affinity for 02 which promotes the release of the remaining O2 - enhancing the ability of the RBC to release O2 near tissues which need it most
What is the Bohr effect?
Hb 02 binding affinity is inversly related to the acidity and CO2concentration
What causes the dusky discolouration in cyanosis?
Ferrous iron converting to ferric iron –> methemoglobin which is darkly coloured in the presence of low 02 levels
What’s the name of the enzyme which converts CO2 to H2CO3?
Carbonic anhydrase
What is the choride shift and what is its purpous?
Exchange of bicarbonate out of the RBC for chloride into the the RBC
Keeps the osmolarity of the RBCs constant and promotes the formation of more HCO3- in the RBC
What is bilirumin converted into when the skin is exposed to white light?
Lumiverdin
What is Hb broken down into by macrophages?
What happens to the iron?
Heme –> biliverdin –> bilirubin (excreted in the bile)
Iron is re-used for Hb synthesis
Which is the most likely pathogen to cause pneumonia in an otherwise healthy person?
Streptococcus pneumoniae 60-75%
Which organisms are most likely to cause HAP?
- Haemophilus influenzae
- Staphylococcus aureus
- MRSA
Which organism causes pneumonia in immunosupressed patients?
PCP
TB
Fungi
Which Gr+ bacteria causes lobar pneumonia?
Strep pneumoniae
Haemophilus influenzae usually causes pneumonia in which group of chronic illnesses? (2 listed)
COPD
CF
Which Gr+ve bacteria causes destruction of the lung parenchyma leading to cavitation?
Staph aureus
Which bacteria colonises in the oropharynx and causes pneumonia due to dysphagia?
Red current jelly sputum
Klebsiella
Which bacteria causes aspiration pneumonia?
E. coli
Which bacteria causes pea grean sputum in chronically ill patients?
Pseudomonas aeriginosa
Which bacteria causes pneumonia infection in people through contaminated water?
Legionella pneumophilia
What are the signs and symptoms of someone with legionella pneumonia? (7 listed)
- Dry cough
- fever
- rash
- Diarrhoea
- oliguria
- ARF
- HSM
- rhabdomolysis
Which organism mostly affects closed populations?
Mycoplasma pneumonia
Which bacteria causing pneumonia is transmitted to humans from birds?
Chamydia psittaci
What are the signs and symptoms of Chlamydia psittaci?
(6 listed)
- fever
- myalgia
- rasg
- splenomegaly
- severe cough
Which test measures the functional residul capacity of the lungs?
Helium dilution test
Which law does body plethysmography utelise to calculate lung volume?
Boyle’s law
Which law does DCLO utelise to measure the integrity of the alveolar/capillary membrane in a pulmonary function test?
Fick’s law
What can cause a reduction in DCLO (diffusion capacity of Carbon monoxide)?
- reduced alveolar space → e.g. emphysema
- increased alveolar/capillary membrane thickness → e.g. interstitial lung disease
What does CURB65 indicate?
- Confusion
- Urea > 7
- RR > 30
- SBP < 90 DBP <60
- Age >65
What score on the CURB65 are people admitted to hospital?
2
What CURB65 score would you consider admission to ITU?
4-5
What investigations should be done when suspecting pneumonia?
(SUBEX)
- Sputum → AFB, culture, gram stain
- Urine →legionella antigen, if output <30ml = ARF
- Bloods → FBC, culture, U&EC
- ECG
- X-ray → CXR
Which abx would you prescribe when treating a complicated pneumonia?
- IV cefuroxime + PO clarythromycin
OR
- IV augmentin + clarythromycin
In which pneumonias would you consider using IV metronidazole (i.e. anaerobic) + IV cefuroxime?
(2 listed)
- cavitation pneumonia
- aspiration pneumonia
