A 24-year-old man with a known history of sickle cell anemia presents to the emergency dep… — USMLE Step 2 CK

A 24-year-old man with a known history of sickle cell anemia presents to the emergency department reporting acute-onset chest pain, shortness of breath, and a productive cough. His symptoms began 12 hours ago and have progressively worsened. His temperature is $38.6^\circ C$ ( $101.5^\circ F$ ), blood pressure is 110/70 mm Hg, pulse is 118/min, and respiratory rate is 28/min. Oxygen saturation is 88% on room air. Physical examination reveals dullness to percussion and decreased breath sounds over the right lower lung field.

Laboratory evaluation shows:
Hemoglobin: 7.0 g/dL
Leukocyte count: $18,000/mm^3$
Platelet count: $450,000/mm^3$
Reticulocyte count: 14%

Arterial blood gas on room air:
$pH$ : 7.48
$PaO_2$ : 55 mm Hg
$PaCO_2$ : 30 mm Hg

Chest radiograph demonstrates a new right lower lobe consolidation.

Which of the following is the most appropriate next step in the management of this patient?

Intravenous ceftriaxone and azithromycin, supplemental oxygen, and cautious fluid hydrationCevap
B
Intravenous furosemide and initiation of noninvasive positive pressure ventilation
C
Oral amoxicillin monotherapy and discharge with close outpatient follow-up
D
Administration of intravenous sodium bicarbonate
E
Measurement of serum thyroid-stimulating hormone and free thyroxine levels

Cevap

Intravenous ceftriaxone and azithromycin, supplemental oxygen, and cautious fluid hydration

The patient is experiencing acute chest syndrome (ACS), a leading cause of mortality in sickle cell disease. It is defined by a new radiodense pulmonary infiltrate combined with fever, chest pain, tachypnea, wheezing, or cough. Because it is often impossible to distinguish infectious from non-infectious causes (such as fat embolism or in situ microvascular thrombosis) on initial presentation, and because atypical organisms (e.g., Mycoplasma pneumoniae, Chlamydia pneumoniae) frequently play a role, standard treatment mandates immediate broad-spectrum antibiotics. A third-generation cephalosporin (e.g., ceftriaxone) combined with a macrolide (e.g., azithromycin) is the regimen of choice. Additionally, supportive care with supplemental oxygen to treat hypoxemia and careful intravenous fluid hydration (to prevent hypovolemia-induced sickling while avoiding pulmonary fluid overload) are essential next steps.

Adım Adım Çözüm

Identify the primary clinical syndrome based on the patient's history and presentation.

The patient has sickle cell anemia, fever, hypoxemia, chest pain, and a new pulmonary consolidation, establishing the diagnosis of acute chest syndrome.

Recognizing the triad of fever, respiratory symptoms, and a new pulmonary infiltrate in a sickle cell patient is critical for timely, life-saving intervention.

Analyze the arterial blood gas results to evaluate respiratory status.

The ABG shows hypoxemia (

PaO_2

55 mm Hg) and respiratory alkalosis (

pH

7.48,

PaCO_2

30 mm Hg) driven by tachypnea.

This rules out a primary metabolic acidosis and confirms the need for immediate supplemental oxygen rather than chemical buffering with bicarbonate.

Determine the standard of care for acute chest syndrome.

Empiric broad-spectrum antibiotics (a third-generation cephalosporin plus a macrolide), oxygen therapy, pain management, and careful hydration.

Acute chest syndrome can be triggered by infection (including atypical bacteria like Mycoplasma and Chlamydia), fat embolism, or pulmonary infarction, necessitating comprehensive empiric coverage.

Anahtar Kavram

Management of Acute Chest Syndrome in Sickle Cell Disease

Tahmini Süre:1m 30s

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

Bu konudan daha fazla soru