CR Revision 5 Flashcards
What determines the alveolar to arterial PO2 difference? [1]
What is usual Alveolar-arterial O2 difference not normally greater than? [1]
Shunting determines the alveolar to arterial PO2 difference
The normal A-a O2 difference is not normally greater than 1.3 kPa
How do you calculate normal aterial PaO2? [1]
Normal PaO2 = 13.6 – (0.044 x age in yrs) kPa
What is shunting (of the lungs)? [1]
What can shunting be caused by [1]
]
When an area of the lung is perfused but not ventilated. Blood is transported through the lungs without taking part in gas exchange
Can be caused by Arteriovenous malformations (AVMs)
What causes changes in oxygen dissociation curve?
Shifts to L → Lower oxygen delivery, caused by:
Low [H+] (alkali)
Low pCO2
Low 2,3-DPG
Low temperature
Label A & B [2]
A: Lung failure
B: Pump failure
Type 2 Respiratory Failure is an imbalance between which three factors? [3]
Imbalance between:
- Neural respiratory drive
- Load of resp. muscles
- Capacity of the resp. muscles
LEARN ! Name 4 reasons that could cause hypoventilation
Increased resistance as a result of airway obstruction (e.g.COPD)
Reduced compliance of the lung tissue/chest wall (e.g. pneumonia, rib fractures, obesity).
Reduced strength of the respiratory muscles (diaphragm) (e.g. Guillain-Barré, motor neurone disease)
Drugs acting on the respiratory centre reducing overall ventilation (e.g. opiates)
Name three consequences of CO2 retention [3]
State for each their clinical signs [3[
End-organ hypoxia
- Altered mental status
- Bradycardia and hypotension (late)
Haemoglobin desaturation
- Cyanosis
CO2 Retention
- Flap (asterixis): ask a patient to extend arms out, close eyes, should be able to hold for 30 secs
- Bounding pulse
What would be the threshold limit pulse ox saturation (SpO2) that is a critical threshold?
~94% is a critical threshold. Below this level a small fall in PaO2 produces a sharp fall in SpO2
If the SpO2 is >94% the the PaO2 should be >[]kPa
If the SpO2 is >94% the the PaO2 should be >10kPa
First line of treatment for respiratory failure? [1]
Oxygen
If giving oxygen therapy, what is SpO2 target?
94-98%
Avoid hyperoxia in patients recieving supplemental oxygen !
Which type of patients would require the following?
- Oxygen masks / nasal cannulae
- Face mask with reservoir bag
- Venturi mask
Oxygen masks, nasal cannulae
Patient with normal vital signs (post-op)
Face mask with reservoir bag
Higher O2 concentration needed (asthma attack, pneumonia, sepsis)
Venturi mask
Controlled treatment in long-term respiratory failure (COPD)
Describe how conduct oxygen therapy?
High flow Oxygen
Continuous oximetry should be started immediately
Monitor:
Vital signs
ABGs
What are the two main mechanisms that cause ischaemic stroke? [2]
- Thrombosis: The formation of a blood clot in an artery normally at the site of an atheroma or atherosclerosis.
- Embolism: An embolus blocks a downstream artery after originating from somewhere else in the body, usually having broken off from a thrombus.
Explain MoA of how atherosclerosis causes ischaemic stroke
Endothelial damage allows lipoproteins and monocytes to adhere to the vessel wall and enter the intima.
Monocytes differentiate into macrophages and engulf the lipoprotein and become known as foam cells.
Further accumulation of cholesterol and foam cells forms a fatty streak.
Foam cells release pro-inflammatory cytokines which leads to smooth muscle cell proliferation. and connective tissue to deposition in the fatty streak.
These changes form a fibrous cap over the lipid core.
A necrotic core can form due to the lack of capillaries.
Plaque rupture removes the endothelium which exposes the fibrous cap leading to thrombosis and occlusion of the artery
What is a watershed ischaemic stroke? [1]
Sudden BP drop by more than 40mmHg, then there is low cerebral blood flow = global ischaemia leading to ‘watershed infarcts’ in vulnerable areas of cortex between boundaries of different arterial territories
brain ischemia that is localized to the vulnerable border zones between the tissues supplied by the anterior, posterior and middle cerebral arteries
When is common to see watershed stroke?
Sepsis patients
What is the most important risk factor for Haemorrhagic stroke? [1]
Hypertension !
Whats the difference between Intracerebral haemorrhage vs Subarachnoid haemorrhage (SAH)?
Which causes a thunderclap headache?
Intracerebral haemorrhage is bleeding into the brain parenchyma: basal ganglia particularly effected
SAH is bleeding into the subarachnoid space. thunderclap headache
Which artery is most common to have a stroke in? [1]
Middle cerebral artery
Which drug classes would use for primary prevention of stroke? [3]
Control of which disease would allow prevention of stroke? [1]
Primary prevention:
- Cholesterol: statin
- AF: anticoagulation
- Good diabetic control
- BP: antihypertensives
What are the 3 overlying causes of cellular death in stroke? [3]
Mechanical compression
Cerebral Oedema
Excitotoxicity
Excitotoxicity of stroke
What is first step for diagnosis you do when suspect stroke patient? [1]
Get them to have a non-contrast CT scan: rule out haemorrhage stroke
How would you treat acute ischameic stroke:
- if within 4.5 hrs of onset [1]
- if outside 4.5 hrs of onset [1]
Thromboylsis:
- using drug - Alteplase
- Must occur within 4.5 hours of onset
- haemorrhage has to be excluded
Mechanical thrombectomy
- endovascular removal of a thrombus from a large artery.
What drug would you initially give to non-haem stroke? [1]
Aspirin !
How would you manange an acute TIA?
300mg Aspirin
Refer urgently to TIA clinic (to be seen within 24 hours). In clinic: work out if was stroke or not.
Might do ECG to see if have AF
draw the circle of willis xxx
Label A-C
A: anterior cerebral artery
B: middle cererbral artery
C: internal carotid artery
What are a common consequence of prolonged or recurrent inflammation, particularly allergic inflammation in respiratory system? [1]
Nasal polyps are oedematous protrusions of the respiratory mucosa and are a common consequence of prolonged or recurrent inflammation, particularly allergic inflammation.
Describe 3 histological changes seen in asthma Ptx? [3]
Asthma causes:
- SM hyperplasia (due to increase in muscle use
- Basement membrane thickening
- Mucus hyperplasia
Which part of the respiratory system is the main site of SABA action? [1]
Smaller airways in tracheal / bronchial tree: requires smooth muscle to be there (to relax)
Which secretory protein is associated with pathologies such as COPD and asthma? [1]
Which cell secretes? [1]
Secretory protein C16: associated with pathologies such as COPD and asthma.
non-ciliated bronchiolar Clara cells This protein increasingly appears to protect the respiratory tract against oxidative stress and inflammation
What histological changes do you see in bronchitis? [4]
goblet cell metaplasia
mucous plugging
inflammatory cell infiltration (lymphocytes and macrophages)
fibrosis
mucus gland hypertrophy
What are the histopatholigcal features of TB? [4]
Langhan cells
immune cell infiltration
granulomas; have central necrosis and cavitation
tissue destruction
Which of the following depicts the Langhan cell in TB Ptx?
A
B
C
D
Which of the following depicts the Langhan cell in TB Ptx?
A
B
C
D
Histopathological features in pneumonia? [1]
aggregates of neutrophils (almost like an abscess) in the alveolar
Where are sq cell carcinomas (SCCs) most often found (lung)? [1]
Hilum
Name a risk factor for squamous cell carcinoma [1]
What are histological changes are induced by ^? [2]
Often centrally located close to hilum
Smoking is a risk factor:
- Leads initially to metaplasia (from respiratory to squamous epithelium) then dysplasia.
- Smoke procarcinogens can be converted to carcinogens via P450
What may be indicative of paraneoplastic syndrome due to Squamous Cell Carcinoma? [1]
Hypercalcemia may be indicative of paraneoplastic syndrome due to SCC
Cytological features of Squamous cell C? [3]
- small cells
-
Pleomorphic, Polygonal cells [1]
with high nuclear to cytoplasmic ratio [1]
with island of keratinisation [1](orange, Normal bronchial cells are azure/blue) - Larger tumours may have extensive necrosis
Histopathological features of Cytological features of Squamous cell C? ? [5]
- Small, malignant cells often very large with eonisophilic cytoplams [1] and large vesicular nucleus [1]
- High nuclear:cytoplasm ratio
- Intercellular bridges
- Keratin pearls [1]
Histopathological features of adenocarcinoma? [3]
irregular, closely packed glands effacing normal lung appearance with atypical cells lining the gland lumen
glandular hyperplasia
desmoplastic (fibrotic) stroma around them.
Histopathological features of small cell carcinoma? [3]
malignant neuroendocrine neoplasm found centrally in the lung
small oval rounded cells with scarce cytoplasm and irregular borders: morphology where can only see nuclei - looks like nuclei molding
extensive necrosis
mitosis ++++++++++++++
What type of T helper cells are found in granulomas? [1]
TH1 subtype
Describe that pathophysiology of granuloma formation
- Antigen taken up by macrophage & presented to CD4+ helper T cells
- CD4+ helper T cell convert to TH1 subtype
- TH1 cells screte IL-2 and INy
- T cell proliferation and macrophage activation
- Macrophages and T cells secrete TNFa
- Causes increase in inflammatory cells
- Causes repeat of TH1 cells screte IL-2 and INy etc
Label A-D of this granuloma
Which of the following is lobal pneumonia and which is bronchopneumonia?
Left: Bronchopneuomia
Right: Lobal pneumonia
What changes do COPD small airways undergo with developement on the disease? [1]
COPD small airways demonstrate marked remodelling, with the overall thickness of the airway wall increased compared to smokers without airflow limitation
- epithelial changes
- mucoid plugs
- increased density of inflammatory cell
- smooth muscle hyperplasia and fibrosis
Name the type of lung cancer depicted
metastatic small cell carcinoma - blue cluster
note:
- orange myeloid precursors
- fat cells
- blue erythoid precursors
- megakaryocytes
Which of the following arrows shows a thickened basement membrane in asthma patient?
A
B
C
D
Which of the following arrows shows a thickened basement membrane?
A
B
C
D
