Respirology - Radiography

Question 1

Discuss signs of consolidation

Answer 1

- filling of airspace with fluid, pus, blood or cells
Radiological Signs
- increased opacity obsuring pulmonary vessels
- air bronchogram sign
- silhouette sign
      - RML = right heart border
      - RLL = right hemi-diaphragm
      - Lingula = left heart border
      - LLL = left-hemidiaphragm

Question 2

Discuss signs of atelectasis

Answer 2

• collapse of alveoli
  Radiological Signs
• volume loss indicating elevated hemidiaphragm, mediastinal and tracheal shift toward ipsilateral side
• increased opacity of the collapsed part of lung with straight margin
• no air bronchogram

Question 3

Discuss signs of pleural effusion

Answer 3

• increased pleural fluid that may displace the lung
  Radiological Signs
• blunting of costophrenic angle
• increased opacity with a meniscus
• tracheal shift towards contralateral side

Question 4

Discuss signs of lung mass

Answer 4

• nodule: discrete focal opacity <3cm in diameter, benign 65% of time
• mass: discrete focal opacity >3cm in diameter, malignant 95% of time
• benign lesions tend to be small <1cm, have stable size for 2 years, have smooth margins and have diffuse or central calcifications

Question 5

Discuss signs of pneumothorax

Answer 5

- air in pleural space
Radiological Signs
- air outside of lung
- no vessel marking
- sharply demarcated edge
- tracheal shift to contralateral side

Question 6

Discuss signs of pulmonary edema

Answer 6

- increased fluid in interstitial space
Radiological Signs
- reticular markings
- Kerley B lines
- bronchial wall thickening
- vascular indistinctness of hila
- vascular redistribution 
- cardiomegaly and bilateral pleural effusion

Question 7

Discuss findings in the Pulmonary Function Test

Answer 7

Flow Volume Loop
- scooped flow volume loop suggest obstructive disease
- peaked flow volume loop suggest restrictive disease
Look at FEV1/FVC, FVC, and TLC
- FEV1/FVC <70% predicted then obstructive or mixed
- TLC <80% then mixed
- FVC >80% and TLC >80% then obstructive
- FEV1/FVC >70% then restrictive or normal
- FVC >80% and TLC >80% then normal
- FVC <80% and TLC <80% then restrictive
Look at DLCO to narrow differential
- normal with DLCO >80% then normal
- normal with DLCO <80% then pulmonary vascular disease, anemia, smoking, early interstitial lung disease
- restrictive with DLCO >80% then chest wall or neuromuscular disease
- restrictive with DLCO <80% then interstitial lung disease
- obstructive with DLCO >80% then asthma, chronic bronchitis
- obstructive with DLCO <80% then emphysema

Question 8

Discuss the severity by PFT results

Answer 8

Obstructive
- FEV1 >80% mild
- FEV1 50-80% then moderate
- FEV1 30-50 then severe
- FEV1 <30 then very severe
Restrictive
- TLC <80% then mild
- TLC 50-80% then moderate
- TLC <50 then severe
DLCO
- 60-80% then mild
- 40-60% then moderate
- <40% then severe

Question 9

Discuss the causes of hypoxemia

Answer 9

Low FiO2
- low fraction of inspired O2
- normal Aa gradient
- high altitude
Hypoventilation
- Decreased minute ventilation
- normal Aa gradient, corrected with supplemental O2
V/Q Mismatch
- abnormal ventilation to perfusion ratio
- increased Aa gradient, corrected with low to moderate O2 supplementation
- asthma, COPD
- pneumonia
- interstitial lung disease
- pulmonary hypertension or pulmonary embolism
Diffusion Block
- abnormal alveolar capillary interface that decrease gas diffusion
- increased Aa gradient, exercise induced/exacerbated hypoxemia
- pneumonia, pulmonary edema
- interstitial lung disease
Shunt
- right to left shunt when blood passes from right to left side of heart without being oxygenated
- increased Aa gradient, cannot be corrected with O2
- atelectasis
- severe pneumonia, pulmonary edema
- right to left cardiac shunt

Question 10

Discuss the Aa gradient

Answer 10

Aa= [FiO2(Patm-PH2O)-(PaCO2/RQ)] - PaO2
Aa=[150-1.25(PaCo2)]-PaO2
- normal <15mmHg