Respiratory pathology

Question 1

22759 – Pulmonary emboli may cause
1: pulmonary artery atherosclerosis
2: chronic pulmonary hypertension
3: no clinical effect
4: cardiogenic shock

Answer 1

TTTT
Robbins 5th ed. Chapter: 4 Page: 111

Question 2

27114 – Patients with significant pulmonary embolism usually show on investigation all except
A. ECG changes with ST depression and T inversion
B. defects in pulmonary perfusion scans
C. normal pulmonary ventilation scans
D. arterial hypoxaemia with increased A-a oxygen tension difference
E. normal chest X-ray, at least initially

Answer 2

A
Investigations are also difficult in pulmonary embolism. Disparity between the ventilation and perfusion scans in nuclear medicine techniques is highly specific and usefully sensitive for haemodynamically significant emboli. The ventilation-perfusion mismatch is apparent on blood gas investigations, where there is an alveolar to arterial oxygen tension difference. Chest X-ray is initially unhelpful; the wedge-shaped radiological opacity occurring later as the lung in the territory of the obstructed artery consolidates. ECG changes are seen in a small minority of patients - those with severe right ventricular overload from pulmonary hypertension. Thus, option A is inconsistent with the majority picture, and is therefore the required answer.

Question 3

15810 – Extensive pulmonary fat embolism may
1: result from severe soft tissue trauma
2: cause disseminated intravascular thrombocoagulation
3: cause the adult respiratory distress syndrome
4: result from abdominal trauma in the alcoholic

Answer 3

TTTT
The normal adipose tissue and the extensive amount of fat which may be present in the liver of the alcoholic can form the reservoir from which the embolic material in fat necrosis emanates. The previous idea that the fat in fat embolism arises from some enzymatic activation of triglyceride formation within the plasma or ‘in situ’ in the lung, currently has no takers.

Question 4

13110 – Pulmonary oedema is a recognised complication of
1: head injury
2: aspiration of a pleural effusion
3: uraemia
4: right ventricular failure

Answer 4

TTTF
Pulmonary oedema occurs in a number of circumstances. Neurogenic factors may be important, eg following head injuries and as a complication of neurosurgery (A true). It is a recognised complication of the rapid withdrawal of a pleural effusion (B true) and of uraemia (C true). The pathophysiological mechanisms involved in the last two examples are not entirely clear. Pulmonary oedema is more likely to complicate left ventricular failure than right ventricular failure (D false).

Question 5

12554 – A patient with pulmonary infarction is most likely to have had
A. pulmonary hypertension
B. chronic obstructive airways disease
C. right ventricular failure
D. passive venous congestion of lungs
E. chronic bronchitis

Answer 5

D
Any of the diseases listed may precede pulmonary infarction. However, the lung has a double blood supply, and pulmonary vascular obstruction is normally unlikely to cause infarction. Infarction is likely only in the presence of a compromised pulmonary circulation. Thus, patients with chronic venous congestion of the lungs are more likely to develop a pulmonary infarct following pulmonary obstruction than patients with the other diseases listed.

Question 6

9810, 16880 – Carcinoma of the bronchus may cause
1: hypocalcaemic syndrome of pseudohypoparathyroidism
2: Cushing’s syndrome
3: hyponatraemia
4: inappropriate secretion of norepinephrine

Answer 6

FTTF
Robbins, 6th ed, Ch 8. I am unaware of the occurrence of either syndrome 1 or 4 in neoplasia as a ‘para’ neoplastic syndrome (epinephrine secretion in phaeochromocytoma, for instance, is predictable). Options 2 and 3 are common in lung cancer.

Question 7

25982 – In the causation of decompression sickness, the nitrogen
1: may cause physical tissue damage
2: may cause ischaemic tissue damage
3: dissolves preferentially in lipid
4: preferentially causes damage in areas of rich blood supply

Answer 7

TTTF
Robbins 5th Edition PAGE: 113, 401

Question 8

15740 – S: Separation of respiratory epithelium from basement membrane often occurs in acute attacks of allergic asthma because R: major basic protein, secreted by eosinophils reacting in IgE-mediated inflammation, causes epithelial cell injury.

Answer 8

S is true, R is true and a valid explanation of S
The prolonged effects of an acute asthmatic attack are due to the chemotactic effects of leukotrienes (the old SRSA) and especially the eosinophil chemotactic effect, these cells being responsible for the exocytosis of major basic protein - a powerful parasitoxic agent, but in this clinical situation, bringing about tissue injury without benefit.

Question 9

25680 – In a post-operative patient with respiratory failure and compromised breathing
A. pulse oximetry is a useful tool to monitor hypercapnia
B. inadequate oxygenation in the presence of an FIO2 of 0.6 implies an unstable patient who needs further diagnosis and definitive treatment
C. decreased level of consciousness is most commonly due to opiate medication rather than hypoxia or hypercarbia
D. if the patient is hypoxic, delivery of high flow oxygen by mask is the first intervention required
E. if ventilation is required, minimum minute volume (tidal volume x respiratory frequency) is 10 ml/kg

Answer 9

B