Respiratory

Question 1

SMART-COP criteria

Answer 1

• Systolic BP (less than 90 mmHg) - 2 pt
• Multilobar CXR involvement - 1 pt
• Albumin (less than 35 g/L) - 1 pt
• Respiratory rate (≥30) - 1 pt
• Tachycardia (≥125) - 1 pt
• Confusion - 1 pt
• Oxygenation (PaO2 ≤59 mmHg, SaO2 ≤90%, PaO2/FiO2 ≤249) - 1 pt
• pH arterial (less than 7.35) - 2 pt

Severe CAP = score ≥5

Question 2

CURB65 score

Answer 2

• Confusion, AMT ≤8
• Urea >7mmol/L
• Respiratory rate ≥30/min
• Blood pressure less than 90/60 mmHg
• Age 65 or more

Severe CAP = score ≥3

Question 3

Long term O2 therapy indications

Answer 3

PaO2 ≤55 mmHg or SaO2 ≤88%
OR
PaO2 ≤59 mmHg or SaO2 ≤89%, with:
 - ECG evidence of P pulmonale 
- Hematocrit >55 percent 
- Clinical evidence of right heart failure

Question 4

Hb-oxygen dissociation curve left shift

Answer 4

Carbon monoxide
Foetal haemoglobin

Decrease in:
Temperature
Acidity
2,3-DPG
pCO2

Question 5

Hb-oxygen dissociation curve right shift

Answer 5

Increase in:
Temperature
Acidity
2,3-DPG
pCO2

Question 6

Alveolar-arterial gradient (A-a gradient) calculation

Answer 6

=FiO2(Patm - PH2O) - PaCO2/0.8 - PaO2

=0.21 (760 - 47) - 1.25(PaCO2) - PaO2

Question 7

Normal A-a gradient

Answer 7

Less than 15mmHg:

• Hypoventilation (high PaCO2) - CNS depression, neuromuscular disease, kyphoscoliosis, obesity hypoventilation
• Low PiO2 (low PaCO2) - altitude, aircraft cabin

Question 8

Widened A-a gradient

Answer 8

Equal or greater than 15mmHg:

• Diffusion defect (normal PaCO2) - ILD, elite athlete during exercise
• V/Q mismatch (normal PaCO2, overcome by high flow O2) - pneumonia, APO, ARDS, atelectasis, ILD
• Right-left shunt (normal/low PaCO2, true shunt not overcome by high flow O2) - PFO, ASD, pulmonary AVM
• Increased O2 extraction

Question 9

Blood gas - Methaemoglobinaemia

Answer 9

• Chocolate brown blood
• Normal PaO2
• SaO2 usually 85-90%
• Saturation gap (Oximetry SaO2 5% lower than ABG SpO2)

Question 10

Blood gas - Carboxyhaemoglobinaemia

Answer 10

• Cherry red skin and lips
• Normal PaO2
• Decreased ABG SpO2
• Normal oximetry SaO2

Question 11

Methacholine provacation test

Answer 11

Specific for asthma diagnosis.

Reduction in FEV1 of 15% or more, using 4mg/ml or less.

Question 12

Bronchodilator reversibility

Answer 12

Increase in FEV1 by at least 12% and 200ml.

Question 13

Best predictor of mortality in COPD

Answer 13

Acute exacerbation with hospital admission

Question 14

Spirometry - asthma

Answer 14

FEV1 ≤80%
FER ≤70%
DLCO ≥75% (normal or high)
TLC ≥80%
Bronchodilator response - more than 12% and 200ml

Question 15

Major form of carbon dioxide in the blood

Answer 15

Bicarbonate ion - 80%
Carbamino compound bound to Hb - 10%
Dissolved in plasma - 10%

(Diffuses to RBC then rapidly anhydrated by intracellular carbonic anhydrase to carbonic acid, then dissociates to bicarbonate)

Question 16

Obstructive sleep apnoea - cardiac physiology

Answer 16

Increased LV afterload
Decreased LV preload
Increased RV venous return
Increased sympathetic outflow
Decreased stroke volume (during apnoea) - increased with relief from obstruction

Question 17

Obstructive sleep apnoea - definition

Answer 17

Polysomnography with more than 5 obstructive events per hour with symptoms/comorbidities, or more than 15 obstructive events per hour regardless

Question 18

Central sleep apnoea - definition

Answer 18

Polysomnography with more than 5 central events per hour with symptoms/comorbidities, and no Cheyne-Stokes breathing

Question 19

Obesity hypoventilation syndrome - definition

Answer 19

Obesity - BMI more than 30
Alveolar hypoventilation - PaCO2 more than 45mmHg (while awake, with no other cause)
Nocturnal hypoventilation - increase in PaCO2 more than 55mmHg or rise of 10mmHg exceeding 50mmHg for 10 min or more

Question 20

Narcolepsy - definition

Answer 20

EDS - more than 3 months
Mean sleep latency - 8 minutes or less
SOREM - 2 or more naps with sleep onset to REM within 15 minutes

Type 1 - CSF hypocretin-1 less than 110 picograms/ml, cataplexy present
Type 2 - normal CSF hypocretin-1, cataplexy absent

Question 21

Chronic obstructive pulmonary disease (COPD) - criteria for long-term azithromycin prophylaxis

Answer 21

COPD with 2 or more exacerbations per year
HR less than 100, QTc less than 450
Sputum culture mycobacterium negative
No baseline high cardiac risk

Question 22

Idiopathic pulmonary fibrosis (IPF) - treatment

aka usual interstitial pneumonia (UIP)

Answer 22

Anti-fibrolytic - pirfenidone or nintedanib

Triple therapy - N-acetyl cysteine, prednisolone, azathioprine

Question 23

Well’s score for pulmonary embolism (PE)

Answer 23

Clinical symptoms of DVT (3)
No alternative diagnosis (3)
Previous DVT/PE (1.5)
Immobilisation/surgery past month (1.5)
Tachycardia more than 100 (1.5)
Malignancy (1)
Haemoptysis (1)

PE likely = score more than 4

Question 24

Spirometry - obstructive defect

Answer 24

FEV1/FRC (ie. FER) ≤70% or LLN

Question 25

Spirometry - restrictive defect

Answer 25

TLC less than 80% or LLN, with normal FER

Question 26

Alpha-1 antitrypsin deficiency (AAT) - lung pathophysiology

Answer 26

Toxic loss of function - AAT normally inhibits elastase, results in proteolytic degradation of elastin

Question 27

Lung transplant - contraindications

Answer 27

``` Uncontrolled infection Malignancy last 2 years Significant dysfunction in other organs Significant coronary artery disease or HF Chest wall / spine deformity Active smoking Drug / alcohol dependency HIV infection / active hep B or C infection Obese BMI ≥35 ```