What other drug can be used for an asthma attack in addition to SABA & ipatropium?
I.v. steroids - hydrocortisone (reduce airway inflammation)
What FEV1:FVC ratio would be indicative of obstructive airway disease?
Less than 0.7/70%
What would be the difference between asthma and COPD in FEV1 after using a bronchodilator?
More than 12% improvement with a bronchodilator (asthma)
How would you describe pneumonia on an x-ray?
Opacification
Why does pneumonia cause hypoxaemia?
Ventilation perfusion mismatch
Why could pneumonia cause a metabolic acidosis rather than a respiratory acidosis? What systemic signs would be present?
Septic shock causes lactic acidosis (accompanied with high HR & low BP)
What type of immunity develops following exposure to the TB bacillus?
Cell mediated immunity
What giant cell is associated with TB?
Langhans giant cell
How would you describe TB on a CXR?
Patchy opacification / Opacification with cavitation
What area of the lung does post primary TB usually occur?
Upper lung zone
How would you diagnose active TB?
TB on sputum smear/culture
Nucleic acid amplification test on sputum sample
Why is non-compliance an issue with TB treatment and how can we solve this?
6 months of abx (patient feels better within few weeks so stops taking them)
Directly Observed Treatment
Why does a baby with Respiratory distress syndrome of the newborn find respiration difficult?
- Surfactant reduces the surface tension of the fluid lining the alveoli
- No surfactant means higher surface tension of the fluid which reduces lung compliance
- lungs are harder to expand/more stiff due to reduced compliance/increased elastic recoil
Why does NRDS cause hypoxaemia?
Ventilation-perfusion mismatch
(poorly ventilated, collapsed alveoli still perfused)
How could a bronchial carcinoma cause left vc paralysis?
Left RLN descends into the thorax, winds around the aortic arch and travels back up to the larynx
Describe the cough reflex
- Deep inspiration following closure of glottis
- Strong contraction of the expiratory muscles
- Sudden opening of the glottis causes an explosive discharge of air
Why does the cough reflex become less effective following a L RLN palsy?
Glottis unable to fully adduct, so muscle contraction cannot build up intrapulmonary pressure
How would you describe a tumour on CXR?
Solitary mass
What are some complications with spread of a bronchial carcinoma?
Paralysis of left hemidiaphragm due to phrenic nerve palsy (breathlessness)
Pneumonia distally to tumour
Pericardial effusion
At the end of expiration what is the pleural pressure in relation to atmospheric pressure and why?
Below atmospheric pressure
Inward elastic recoil of lung vs outward recoil of the chest wall
Why does air enter the pleural cavity in a pneumothorax?
- Opening in the parietal/visceral pleura
- Pleural cavity can communicate with the atmosphere
- Air enters the pleural cavity down the pressure gradient until pleural pressure equilibrates with the atmospheric pressure
Why does the lung collapse in a pneumothorax?
- Pleural seal is broken
- Lung is no longer adhered to chest wall
- Inward elastic recoil of the lung is no longer counter balanced by chest elastic recoil
- Lung collapses towards hilum
What features of a patient history favour COPD rather than asthma?
Older
Constant breathlessness
Chronic rather than triggers
Productive cough vs dry asthma cough
No past of allergy
Smoker history
What is the axis for a volume loop?
Flow and Volume
COPD has scooped/reduced expiration
