21.1 Acute Chest Syndrome

CPHON Test Content Outline (TCO) V.E.1 tests acute chest syndrome (ACS) as a cardiopulmonary emergency in sickle cell disease (SCD). The hematologic-disorder chapter already mapped genotypes, hydroxyurea, penicillin, and fever-as-emergency. The later vaso-occlusive-crisis section owns pain titration. This section is the lung emergency: name ACS, prevent it with incentive spirometry (IS) during vaso-occlusive crisis (VOC), and treat the first film as ACS even when someone says “maybe it is only pneumonia.”

An 8-year-old with hemoglobin SS (HbSS) who will not blow the spirometer during back pain, a 3-year-old with hemoglobin SC (HbSC) who looks “just febrile” with a new infiltrate, and a 16-year-old who becomes confused after long-bone infarcts are the same emergency at different ages. The Oncology Nursing Certification Corporation (ONCC) uses generic drug names. The Association of Pediatric Hematology/Oncology Nurses (APHON) picture is a nurse who sits the child up, starts IS, covers community plus atypical bacteria, and calls for transfusion before the intensive-care door is the only option.

Definition: new infiltrate plus a respiratory clue

ACS is a new pulmonary infiltrate on chest imaging plus at least one of chest pain, fever, tachypnea, wheeze, or cough in a child with SCD. Poor-inspiration films and plate-like atelectasis are not a reason to argue for an hour; they are a reason to sit the child up, start IS, and repeat imaging as ordered. The child who already has hypoxemia, splinting, and a new opacity is in ACS until the team says otherwise.

Treat ACS as an emergency. It is a leading cause of death and intensive-care transfer in pediatric SCD. Do not discharge a febrile child with SCD and a new infiltrate from triage because the saturation is still “pretty good.” Do not teach a parent that a cough during a pain crisis is “just the opioid.” Last week’s clear clinic radiograph does not cover tonight’s VOC.

Walk the 02:00 admission. The 8-year-old with HbSS has lumbar and chest-wall VOC, is on hydromorphone, and lies perfectly still because movement hurts. Morning film was clear. By afternoon the child is febrile, breathing 40 times a minute, and the new film shows a lobar opacity. That clock—from splinted VOC to ACS—is the one IS is meant to break.

Pneumonia versus ACS is a trap—treat as ACS

Infection can start ACS: pneumococcus, other community bacteria, Mycoplasma, Chlamydophila, and respiratory viruses. Fat emboli from necrotic marrow can start ACS. Pulmonary infarction and hypoventilation from pain or opioids can start ACS. At the bedside you cannot reliably separate “community pneumonia” from ACS on the first film. Treat as ACS. That means oxygen, SCD-aware antibiotics, IS, transfusion planning, and hematology involvement, not a five-day walk-in pneumonia pathway that never mentions sickle hemoglobin.

HbSC and HbS–β+-thalassemia still get ACS. Families who heard “milder genotype” delay care; that delay is a nursing failure, the same teaching as in the disease-framework chapter.

Prevention: incentive spirometry during VOC

The highest-yield prevention is incentive spirometry during VOC, especially with chest, back, or abdominal pain and after thoracic or abdominal surgery. Pain and opioids both splint the chest. Splinting produces atelectasis; atelectasis becomes ACS. Implement IS every 1–2 hours while the child is awake. School-age children use a spirometer. Toddlers use play-based equivalents—bubbles, pinwheels, party blowers—because a 2-year-old will not coach to 1,000 mL on a plastic column. Ten slow breaths on the hour is treatment, not busywork.

Do not withhold analgesia to “make them breathe.” Undertreated pain also splints. Titrate so the child can sit up and take a deep breath, then return to rest. A child sleeping through every hour on a patient-controlled analgesia (PCA) without IS is on a path to ACS; wake, sit, blow, then rest. Hydroxyurea and chronic transfusion reduce ACS risk over months. They do not replace tonight’s spirometer.

First actions: oxygen, antibiotics, bronchodilators, transfusion path

Sit the child up. Give supplemental oxygen for hypoxemia, aiming toward the child’s baseline saturation as ordered—ONCC does not publish a single universal target number. Use continuous pulse oximetry. Work of breathing, not one snapshot saturation, drives intensive-care consultation.

Start IS and pulmonary hygiene immediately, even while the radiograph is pending if the child is splinting. Give analgesia that allows deep breaths and watch oversedation.

Antibiotics covering community-acquired plus atypical pathogens are part of ACS care, not an optional add-on after cultures. Typical pediatric combinations pair a third-generation cephalosporin such as ceftriaxone with a macrolide such as azithromycin. Do not send a child with SCD and a new infiltrate home on oral amoxicillin alone and call it done. Follow the treating SCD pathway.

Bronchodilators (albuterol) when there is wheeze or a known reactive-airway component. They are not mandatory for every quiet, non-wheezing exam.

Transfusion or automated exchange when there is hypoxia or rapid progression: worsening tachypnea, multilobar involvement, falling saturation, or neurologic change. Simple transfusion may suffice for milder hypoxia if hemoglobin has room to rise without overshooting viscosity—centers often avoid pushing simple-transfusion hemoglobin much above a protocol ceiling (commonly discussed around 10 g/dL). Use the protocol, not a website, as the number. Exchange transfusion lowers the hemoglobin S (HbS) fraction without raising hematocrit as aggressively and is the severe-ACS, intensive-care, or fat-embolus move. Involve hematology and the blood bank early; do not wait for respiratory arrest to type and cross.

Intensive care for respiratory failure, need for ventilatory support, hemodynamic instability, or multi-organ fat-embolus pictures. Fluids: VOC hydration is not a free-water flood. Overhydration can worsen pulmonary edema. Use ordered volumes and watch intake and output.

Fat embolus after bone infarcts

After bone infarcts—especially long-bone or pelvic VOC in older children and adolescents—necrotic marrow fat can shower the lungs and brain. The picture is ACS plus neurologic change, sometimes thrombocytopenia, petechiae, and multi-organ failure. A 16-year-old with HbSS who had severe thigh pain yesterday and today is hypoxic, febrile, and newly confused has fat-embolus ACS, not a primary psychiatric event and not “just a virus.” Treat as severe ACS: oxygen, community-plus-atypical antibiotics, urgent transfusion or exchange, and intensive care. Do not delay for a specialized fat stain that will not change the first hour.

Monitoring is serial: saturation, respiratory rate, work of breathing, chest exam, hemoglobin, and mental status. A child who was talking and now cannot finish a sentence is failing. Family teaching closes the loop: IS during every home or hospital VOC, call for fever or new cough during a crisis, and do not treat ACS as primary-care bronchitis.

The CPHON product is a child who blew the spirometer during last night’s VOC, a film plus fever that was named ACS the same hour, antibiotics that covered atypicals, and a transfusion conversation that started before intensive care was the only remaining option.