MBBS SAQ · Haematology
Sickle cell disease — acute painful crisis and acute chest syndrome
A final-prof / NEET-PG SAQ on a sickle cell painful crisis that evolves into acute chest syndrome. Expects ABCDE + crisis management (oxygen, hydration, analgesia, treat trigger), recognition of acute chest syndrome as the leading killer, escalation to antibiotics + transfusion, and the preventive pillars (hydroxyurea, TCD screening, functional-asplenia prophylaxis, gene therapy).
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Question
A 16-year-old boy with known HbSS sickle cell disease presents to the emergency department with severe back and limb pain for 24 hours after an upper respiratory infection. He is in marked distress. On examination: temperature 38.6 deg C, RR 26, SpO2 91 percent on air, BP 112/70. Chest is clear. Hb 72 g/L (baseline 78). Four hours after admission, despite analgesia and fluids, he develops worsening dyspnoea, right-sided pleuritic chest pain and new right lower-lobe crackles; repeat SpO2 is 88 percent on air. Outline your assessment, immediate management and the steps to prevent long-term complications.
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Diagnosis: acute vaso-occlusive (painful) crisis evolving into acute chest syndrome (ACS). A painful crisis precipitated by a viral infection is now complicated by the new pulmonary infiltrate, hypoxia and fever — the classic evolution of acute chest syndrome, the leading cause of death in sickle cell disease.[1][2]
Immediate assessment — ABCDE. Airway patent; Breathing — high-flow oxygen to target SpO2 94-98%; Circulation — IV access, fluids; Disability — pain score, analgesia; Exposure — full set of observations, sepsis screen, examine chest, abdomen and neurology. Look for a precipitant (infection, dehydration).[1]
Painful-crisis management.
- Analgesia within 30 minutes — titrated IV morphine (or subcutaneous); add paracetamol and NSAIDs if no contraindication. Never under-treat pain; use a pain ladder and reassess frequently.
- Oxygen to maintain saturation; IV hydration with isotonic saline at maintenance plus a deficit replacement (avoid over-hydration, which worsens ACS).
- Treat the trigger — blood cultures, urine and throat samples; empirical antibiotics if infected; incentive spirometry every 2 hours to prevent atelectasis and ACS.[2]
Recognise and escalate for acute chest syndrome. New infiltrate + hypoxia in a sickle cell patient = ACS. Escalate immediately:
- Broad-spectrum antibiotics — IV cephalosporin (ceftriaxone/cefuroxime) PLUS a macrolide (azithromycin) to cover typical and atypical organisms.
- Transfusion — simple transfusion if Hb has fallen; exchange transfusion if severe (aim HbS under 30 percent), especially with worsening hypoxia, multilobar infiltrate or rapid progression.
- Respiratory support — escalate oxygen, CPAP/BiPAP or invasive ventilation if respiratory failure develops.[1]
Investigations. FBC and reticulocytes, blood film, U&E and LFTs, LDH and bilirubin, group and save/crossmatch, blood and sputum cultures, arterial blood gas if hypoxic, chest X-ray (repeat), viral PCR (including parvovirus B19 if aplasia suspected), and a reticulocyte count to exclude aplastic crisis.
Prevention of long-term complications — the four pillars.[1]
- Hydroxyurea (hydroxycarbamide) — raises HbF, reduces crises by ~50 percent, ACS, transfusions and mortality; recommended for nearly all from 9 months.
- Stroke screening — annual transcranial Doppler (TCD) from age 1-2; chronic transfusion if abnormal (prevents ~90 percent of strokes, STOP trial).
- Functional-asplenia prophylaxis — vaccination against encapsulated organisms (pneumococcal, Hib, meningococcal, influenza) and penicillin V prophylaxis to age 5; any fever = urgent empirical IV antibiotics.
- Curative options — haematopoietic stem cell transplant (matched sibling) and gene therapy (exagamglogene autotemcel / exa-cel, CRISPR-based), approved 2023-2024.
Common errors
- Under-treating pain — withholding or under-dosing opioids causes suffering and tachycardia/hypoxia; titrate IV morphine and reassess.
- Missing acute chest syndrome — attributing the new infiltrate and hypoxia to simple pneumonia and not escalating to transfusion and macrolide cover; delayed recognition is the main cause of ACS mortality.
- Over-hydration — excessive IV fluids cause pulmonary oedema and worsen ACS; use maintenance plus deficit, not aggressive boluses.
- Forgetting the trigger — not screening for and treating infection, parvovirus B19 (aplastic crisis), or dehydration.
- Not considering stroke — failing to perform TCD surveillance in children or emergency exchange transfusion for acute stroke.
Examiner notes
- The exam wants a structured approach: ABCDE -> crisis bundle (oxygen, hydration, analgesia, treat trigger) -> early recognition and escalation of ACS (antibiotics + transfusion, exchange if severe) -> the four preventive pillars.
- State that acute chest syndrome is the leading cause of death and that incentive spirometry and transfusion change outcomes.
- A strong candidate names the evidence base (MSH trial for hydroxyurea, STOP trial for TCD and transfusion, Gaston/PROPS for penicillin prophylaxis) and the curative gene therapy (exa-cel) approved in 2023-2024.[1][2]
References2ShowHide
- [1]Kato GJ, Piel FB, Reid CD, et al. Sickle cell disease. Nature Reviews Disease Primers, 2018.PMID 29542687
- [2]Rees DC, Williams TN, Gladwin MT. Sickle-cell disease. Lancet, 2010.PMID 21131035