Respiratory manifestations of systemic disease — short-answer question

Part A — Recognition and mechanism (10 marks)

a) State the diagnosis and how you recognise it (3 marks)

This boy has acute chest syndrome, defined by a new pulmonary infiltrate on chest imaging together with fever and respiratory signs — here pleuritic chest pain, cough, and hypoxia. The classic and dangerous timing is that it has evolved on day two of admission for a painful crisis rather than being present at arrival, which is exactly when vigilance drops. It is the leading cause of death in sickle cell disease, so it is recognised early and treated presumptively rather than after the full picture completes. [1] [2]

b) Explain the underlying mechanism (4 marks)

Acute chest syndrome is a self-amplifying vicious cycle. A trigger such as infection, a fat embolus from infarcting bone marrow, or pain-driven hypoventilation lowers oxygen, low oxygen promotes sickling in the pulmonary vessels, sickling causes vaso-occlusion and further infarction, and the resulting inflammation and atelectasis worsen oxygenation, which drives yet more sickling. His painful crisis and splinting from chest pain feed directly into this loop. [2] [1]

c) State why prompt action matters (3 marks)

The syndrome can progress within hours from a stable child to respiratory failure, and it is the commonest reason for intensive care and the leading cause of death in this group. Because pneumonia and pulmonary infarction coexist with it and are managed together, over-treating is far safer than trying to exclude it, so early aggressive treatment is the correct response to even an incomplete picture. [1] [2]

Part B — Management, prevention, and the general reflex (10 marks)

a) Outline your acute management (4 marks)

I would give oxygen to correct the hypoxia, provide analgesia sufficient to allow deep breathing while avoiding oversedation that suppresses ventilation, start antibiotics covering typical and atypical organisms, give judicious fluids, and encourage incentive spirometry. I would transfuse for hypoxia or clinical progression, escalating to exchange transfusion for severe or worsening disease to reduce the proportion of sickle haemoglobin, and I would provide respiratory support and involve intensive care if work of breathing or gas exchange deteriorate. [2] [4]

b) State how you would reduce his future risk (3 marks)

I would offer hydroxyurea, which raises fetal haemoglobin and reduces painful crises and acute chest syndrome, with long-term data showing reduced morbidity and mortality, monitoring the blood count for myelosuppression. I would reinforce incentive spirometry during future crises and around surgery to prevent the atelectasis that seeds acute chest syndrome, ensure full immunisation and penicillin prophylaxis as per protocol, and address any coexisting asthma. [3] [4]

c) Describe the general reflex for any systemic disease (3 marks)

In any child with a known systemic disease, I would treat new breathlessness, hypoxia, chest pain, or a persistent infiltrate as a lung complication of that disease until proven otherwise, not a coincidental chest infection. I would sort the child into one of four groups — haematological, connective tissue, immunodeficiency, or malignancy and its treatment — because the group predicts the pattern, the investigation, and the specialist team, and I would investigate decisively and early before the complication becomes irreversible. [2] [1]