Respiratory

Question 1

Describe the physiological process that leads to an increased RV dilatation/ dysfunction in massive PE.

Answer 1

Increased PVR leads to increased pAP and RV afterload –> RV dilatation and dysfunction.

Furthermore, RV dysfunction leads to decreased LV preload leading to hypotension leading to RV ischaemia.

Question 2

Describe the common sings/ symptoms of PE and estimate their incidence.

Answer 2

1. Dyspnoea - Common (73%)
2. Chest pain, pleuritic - implies infarction (often 3-7 days after embolism (66%)
3. Sinus tachycardia (44%)
4. Cough (37%)
5. Haemoptysis (13%)

Note - hypoxia is common but often mild

Question 3

The PERC score to assess probability of PE has 8 criterion, can you name them ?

Answer 3

Pulmonary Embolism Rule-out Criteria
1. Age <50y
2. Pulse <100/min
3. SaO2 > 94% on RA
4. No Haemoptysis
5. No exogenous oestrogen
6. No previous DVT or PE
7. No surgery or trauma within prior 4 months
8. No unilateral leg swelling

If none of the 8 PERC criteria are present, PE can be ruled out clinically.

Note if PE is suspected, apply the Wells Score prior to applying the PERC score - if PERC positive proceed to D-dimer. If PERC negative PE excluded.

Question 4

In a pregnant woman what imaging modality should be used in PE diagnosis?

Answer 4

V/Q Scan - however given pregnant, perfusion only is advised.

Question 5

Describe the treatment duration for PE and unprovoked PE+ Sub-massive/ Massive PE

Answer 5

Provoked PE
- Transient risk factors - 3 months
- Permanent risk factor - Indefinite

Unprovoked PE
- Age >65y, high BMI - consider indefinite treatment with low dose DOAC, e.g. rivaroxaban 10mg daily

Submassive PE
- 6-12 months

Massive PE
- Indefinite
- Note massive PE may require lysis, if SBP is <90mmHg or falls by >40mmHg from baseline. Can be catheter directed/ dose adjusted if concerns for bleeding. Pulmonary embolectomy and VA-ECMO can also be considered

Question 6

In PE, a thrombophilia screen should be performed if under 40y with unprovoked or weak provoking risk factors.

What are the tests within the thrombophilia screen?

Answer 6

Thrombophilia Screen
- Antithrombin 3
- Protein C
- Protein S
- Factor V Leiden
- Plasminogen
- Fibrinogen
- Activated protein C resistance
- Cardiolipin Ab (if under 50y of age)

Question 7

What is the most common cause of bacterial pneumonia? What are some other common causes.

Answer 7

1. Streptococcus pneuomoniae

Other causes include: mycoplasma pneumoniae, staphylococcus aureus, Legionella pneumophila. Enterobacteriaceae.

Pseudomonas aeruginosa pneumonia is rare, and generally only considered if recent ICU admission or previous colonisation.

Question 8

Diagnosis of HAP requires:

Answer 8

Must occur >48h after admission

New CXR changes and 1+ of:
- Fever
- Lymphocytosis/ paenia
- New/ worsening purulent secertions
- Worsening gas exchange

Differential:
- Empyema
- Atelectasis
- PE

Question 9

CURB-65 is a useful scoring tool to stratify the severity of pneumonia. What criterion are present?

Answer 9

C - acute onset CONFUSION
U - URAEMIA (serum urea >7mmol/L or BUN >19mg/dL)
R - RESPIRATORY RATE > 30bpm
B - SBP <90mmHg or SBP <60mmHg
65 - age 65 years or older

*1 point for each

Risk of 30d mortality
0 to 1 - <3%
2 - 9%
3 to 5 - 15 to 40%

Question 10

SMART-COPD is also commonly used in practice to statify severity of pneumonia.

Answer 10

S - SBP < 90mmHg (2 points)
M - Multilobar CXR involvement (1 point)
A - Albumin lower than 35g/L (1 point)
R - RR >25 (if younger than 50y old), RR >30 (if older than 50y old)
T - Tachycardia (>125bpm) (1 point)
C - Acute onset confusion (1 point)
O - O2 sats - see score (2 points)
P - Arterial pH less than 7.35 (2 points)