14.1 Sickle Cell Disease: Acute Chest Syndrome, Stroke & Splenic Sequestration
Key Takeaways
Treat vaso-occlusive pain promptly with individualized analgesia and reassess frequently. Support euvolemia and avoid automatic IV boluses or above-maintenance fluids.
A new pulmonary infiltrate with compatible respiratory symptoms or fever suggests acute chest syndrome. Assess oxygenation, start appropriate antimicrobials, and reassess for progression.
For severe acute chest syndrome, ASH conditionally favors red cell exchange over simple transfusion. The decision and targets depend on severity, starting hemoglobin and the response to initial treatment.
Screen ages 2–16 with HbSS or HbSβ⁰ thalassemia annually using method-specific TCD cutoffs. For a new focal deficit or TIA, arrange prompt transfusion and favor exchange when available. A cautious simple transfusion can bridge if exchange is delayed and hemoglobin is 8.5 g/dL or lower.
Rapid spleen enlargement, acute anemia and poor perfusion suggest sequestration. Give urgently needed red cells in reassessed aliquots because splenic autotransfusion can cause hemoglobin overshoot. A low reticulocyte response suggests aplasia.
Pediatric Sickle Cell Emergencies
Quick Answer: Treat severe vaso-occlusive pain promptly and reassess frequently. Evaluate new respiratory symptoms for acute chest syndrome and escalate support for worsening hypoxemia. In acute anemia, compare the spleen and reticulocyte response with baseline. New focal neurologic findings require urgent stroke evaluation and a transfusion plan.
Why Complications Develop
HbS contains a valine substitution for glutamic acid at position 6 of the mature beta-globin chain. Sickle cell disease includes HbSS and compound heterozygous conditions such as HbSC and HbS beta-thalassemia. Deoxygenated HbS polymerizes and reduces red cell deformability. Intracellular red cell dehydration increases HbS concentration and favors polymer formation. Sickling, cellular adhesion and inflammation impede microvascular flow, while red cell injury causes hemolysis. These overlapping processes help explain pain, anemia and organ injury. HbS polymerization studies · NHLBI sickle cell report
Vaso-Occlusive Pain
Assess reported pain, prior effective doses, opioid exposure, respiratory status and possible complications. Fever, hypoxemia, focal neurologic signs, an enlarging spleen or atypical focal pain changes the evaluation. For ED presentations, ASH recommends assessment and analgesia within one hour of arrival and reassessment every 30–60 minutes. An institutional pathway may reassess sooner during IV titration. Use the individualized pain plan and prior effective doses. When IV access is delayed, an appropriate non-IV route such as intranasal fentanyl can facilitate treatment. ASH pain guideline · CHOP pediatric pain pathway
For example, CHOP lists initial IV morphine 0.1 mg/kg or hydromorphone 0.01 mg/kg in its moderate/severe pain pathway. At 25 kg, the example morphine dose is 2.5 mg before applying local dose limits and prior response. Reassess pain, respiratory rate and sedation before redosing. Consider PCA for ongoing severe inpatient pain with the pain team and an appropriate monitoring plan. ASH found insufficient direct evidence to recommend for or against adding a basal opioid infusion. A short NSAID course can be an adjunct when renal function, bleeding risk and other contraindications allow. Avoid routine meperidine because its metabolite normeperidine can cause neurotoxicity. ASH pain guideline · NHLBI acute pain recommendations
Encourage oral intake when the child can drink. For a euvolemic child unable to drink, NHLBI advises IV hydration at no more than maintenance. ASH made no recommendation for or against routine IV fluids as an analgesic adjunct or for a particular fluid tonicity. Treat clinically significant dehydration or shock separately with reassessment. Consider oral intake, transfusions, renal function, sodium and respiratory status when writing IV orders. Avoid unnecessary fluid loading. Uncomplicated vaso-occlusive pain by itself does not call for transfusion. NHLBI acute pain recommendations · ASH pain guideline
Fever during a pain episode calls for prompt infection assessment. NHLBI recommends blood cultures and empiric parenteral antibiotics at 38.5°C or above, with local pathways setting operational thresholds. NHLBI sickle cell report
Acute Chest Syndrome
Suspect acute chest syndrome (ACS) with a new pulmonary infiltrate and compatible symptoms such as fever, chest pain, cough, tachypnea, wheeze or new hypoxemia in a child with sickle cell disease. Research criteria often specify at least one lung segment and exclude isolated atelectasis. Infection can cause ACS. Pulmonary fat embolism, infarction and hypoventilation from splinting can also contribute. Reassess respiratory status during a pain admission because ACS can develop after admission. Multicenter ACS cohort · Study definition
Check oxygenation and obtain chest imaging, CBC/reticulocytes and type and screen or crossmatch as indicated. Give oxygen for hypoxemia and escalate respiratory support as needed. Use empiric coverage of typical and atypical organisms under the local pediatric pathway, such as a parenteral cephalosporin plus a macrolide when appropriate. Obtain cultures when indicated and adjust treatment to findings. Treat pain while monitoring ventilation. Use incentive spirometry when developmentally feasible and consider bronchodilator therapy for associated bronchospasm. Incentive spirometry reduced new pulmonary complications in a small randomized study of hospitalized patients with chest or back pain. NHLBI ACS recommendations · Children's Mercy ACS pathway · Incentive spirometry trial
| Clinical course | Transfusion reasoning |
|---|---|
| Moderate ACS | Consider simple transfusion when anemia and the clinical course warrant it and the starting hemoglobin permits a safe increment. ASH allows simple, manual exchange or automated exchange in moderate disease when transfusion is indicated. |
| Severe or rapidly progressive ACS | Escalating oxygen needs, severe hypoxemia, respiratory support, progressive infiltrates or falling hemoglobin prompt urgent hematology and critical care consultation. ASH conditionally favors automated or manual red cell exchange over simple transfusion for severe ACS. Automated exchange reduces HbS more rapidly when available. |
| Poor response or high starting hemoglobin | Consider exchange if the child deteriorates despite simple transfusion or if a high pretransfusion hemoglobin limits a safe simple transfusion. Confirm targets and antigen matching with transfusion medicine. Avoid raising hemoglobin excessively while a high HbS fraction remains. |
There is no single universal severity cutoff or post-exchange target for all ACS. Stabilize the child while arranging the appropriate transfusion. Review prior antigen profiles and antibody history with the blood bank. ASH recommends Rh C/E and Kell matching beyond ABO/RhD in sickle cell disease. Coordinate product availability urgently. ASH transfusion support guideline, recommendations 6a and 6b
Acute Ischemic Stroke and Transcranial Doppler Screening
ASH recommends annual TCD at ages 2–16 years for children with HbSS or HbSβ⁰ thalassemia. In the distal internal carotid or proximal middle cerebral artery, nonimaging TCD below 170 cm/s is normal and 170–199 cm/s is conditional, warranting earlier reassessment. For treatment decisions ASH uses two nonimaging measurements at least 200 cm/s or one over 220 cm/s. Imaging TCD uses two at least 185 cm/s or one over 205 cm/s. Document the technique. In a high-resource setting, regular transfusion for qualifying abnormal studies targets HbS below 30% and minimum hemoglobin above 9 g/dL. STOP randomized 130 high-risk children and observed 11 strokes in 67 assigned to standard care versus 1 in 63 assigned to transfusion. The chart shows event counts during the trial. ASH cerebrovascular guideline · STOP trial
New focal weakness, facial droop, dysarthria, aphasia, ataxia or visual symptoms require urgent stroke evaluation and prompt transfusion, ideally within two hours of presentation to care. Arrange emergent MRI/MRA or CT/CTA when MRI is unavailable promptly. Coordinate hematology and transfusion medicine in parallel. Exchange is preferred. If unavailable within two hours and hemoglobin is 8.5 g/dL or lower, a simple transfusion toward about 10 g/dL can bridge to exchange. Above 8.5 g/dL, favor exchange to reduce hyperviscosity risk. Typical post-apheresis targets in ASH guidance are HbS 15–20% and hemoglobin about 10 g/dL, individualized by the team. ASH cerebrovascular guideline · 2026 AHA/ASA AIS guideline
Acute Splenic Sequestration and Transient Aplasia
Check CBC and absolute reticulocyte count, compare with baseline and examine the spleen. A hemoglobin fall of at least 2 g/dL below baseline prompts evaluation for acute anemia causes, including sequestration, aplasia, infection, ACS and delayed hemolytic transfusion reaction when relevant. NHLBI acute anemia and sequestration recommendations
| Feature | Acute splenic sequestration | Transient aplastic crisis |
|---|---|---|
| Mechanism | Sudden splenic pooling reduces circulating red cells and may cause hypovolemic shock. | Temporary suppression of erythropoiesis, commonly from parvovirus B19. |
| Bedside findings | Rapid spleen enlargement, pallor, tachycardia, poor perfusion and sometimes hypotension. Young children with HbSS are at risk. Risk can persist in genotypes that retain splenic function longer. | Pallor and fatigue with a marked fall in hemoglobin. The spleen usually has no acute enlargement from aplasia alone. |
| Blood counts | Reticulocytes are usually increased from a compensating marrow. Platelets may fall with splenic pooling. | Reticulocytes are low for the degree of anemia. Assess for a concurrent process if the findings are mixed. |
| Immediate care | Support perfusion and give urgent, cautiously titrated red cells with hematology. Recheck hemoglobin and spleen size as circulation improves. | Give supportive red cell transfusion for severe or symptomatic anemia and follow recovery of the reticulocyte count. |
In sequestration, trapped cells can return to the circulation as the spleen shrinks. Transfuse in small increments under the local pathway and reassess rather than trying to normalize hemoglobin. In a named U.S. pathway using 2–5 mL/kg aliquots, a selected 5 mL/kg dose for a 10-kg child is 50 mL. The initial goal is to reverse instability while limiting overshoot and hyperviscosity. Resuscitate shock promptly while blood is prepared. Recurrent or severe episodes warrant hematology and surgical follow-up. Teach caregivers how to recognize a changing spleen, pallor and lethargy and when to seek emergency evaluation. NHLBI sickle cell report · Perth Children's emergency pathway · Johns Hopkins All Children’s pathway · Texas DSHS family education
With a recent transfusion and a new hemoglobin decline, evaluate delayed hemolytic transfusion reaction with hematology and the blood bank. ASH describes a significant decline within 21 days with compatible evidence of hemolysis and exclusion of another cause. A fall below the pretransfusion hemoglobin raises concern for hyperhemolysis. Reassess the risk of further transfusion with the treating team. ASH transfusion support guideline
For parvovirus B19-associated transient aplastic crisis, CDC recommends Droplet plus Standard Precautions for seven days. Consult infection prevention for chronic infection in immunocompromised patients and for relevant exposures. CDC isolation guidance
A 9-year-old with HbSS arrives in the emergency department with severe bilateral leg and lower back pain typical of prior vaso-occlusive episodes. The child is afebrile, oxygenation is at baseline and examination shows normal perfusion without dehydration. The child can drink and has an individualized pain plan. What initial approach is most appropriate?
Give prompt opioid analgesia using the pain plan, reassess pain and ventilation, and support oral hydration as tolerated.
Delay analgesia until hemoglobin electrophoresis confirms the cause of the episode.
Start IV hypotonic fluid above maintenance as the primary treatment and reassess pain after hydration.
Begin red cell exchange for the pain alone and defer analgesia until after transfusion.
A 6-year-old with HbSS develops fever, tachypnea, new multilobar infiltrates and oxygen saturation of 86% despite supplemental oxygen during a pain admission. Hemoglobin is 8.4 g/dL and respiratory status is worsening. What immediate plan best fits?
Raise hemoglobin rapidly to 14 g/dL with simple transfusion alone.
Escalate respiratory support, start appropriate empiric antimicrobials and urgently coordinate red cell exchange with hematology and critical care.
Start hydroxyurea as the immediate treatment and reassess for transfusion the next day.
Defer respiratory escalation and antimicrobials until bronchoscopy establishes the cause.
A 15-month-old with HbSS presents with lethargy, marked pallor, weak pulses and blood pressure of 64/34 mmHg. The spleen is newly palpable 6 cm below the costal margin. Hemoglobin is 3.2 g/dL from a baseline of 7.8, platelets are 52,000/µL and reticulocytes are increased. Which diagnosis and transfusion approach best fit?
Transient aplasia. The increased reticulocyte count indicates complete interruption of marrow production.
Delayed hemolytic transfusion reaction. Splenic enlargement alone establishes the diagnosis and requires withholding resuscitation.
Acute splenic sequestration. Resuscitate shock and give urgent red cell aliquots with reassessment to limit hemoglobin overshoot.
Autoimmune hemolysis. Perform splenectomy before giving resuscitation fluids or blood.
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