A 2-hour-old male neonate is evaluated in the neonatal intensive care unit for worsening b… — USMLE Step 2 CK

A 2-hour-old male neonate is evaluated in the neonatal intensive care unit for worsening breathing difficulties. He was born at 31 weeks gestation via emergency cesarean delivery for non-reassuring fetal heart tones. Birth weight is $1,400$ g. APGAR scores were 3 at 1 minute and 6 at 5 minutes. Initial resuscitation included continuous positive airway pressure (CPAP), which is currently being maintained. Vital signs are temperature $36.5^\circ\text{C}$ ( $97.7^\circ\text{F}$ ), heart rate 165/min, respiratory rate 75/min, and blood pressure 55/35 mm Hg. Pulse oximetry shows an oxygen saturation of 82% despite a CPAP of 8 cm H $_2$ O and an FiO $_2$ of 0.60.

Physical examination reveals profound intercostal and subcostal retractions, prominent nasal flaring, and audible expiratory grunting. Skin examination shows scattered 2- to 3-mm erythematous macules containing central yellow pustules over the trunk and proximal extremities. Auscultation reveals symmetrically decreased breath sounds bilaterally. A portable anteroposterior chest radiograph demonstrates a diffuse reticulogranular ground-glass appearance with prominent air bronchograms and low lung volumes.

An arterial blood gas is obtained:

Parameter	Patient Value	Reference Range
pH	$7.18$	$7.35 - 7.45$
pCO $_2$	$66$ mm Hg	$35 - 45$ mm Hg
pO $_2$	$45$ mm Hg	$50 - 70$ mm Hg
HCO $_3^-$	$24$ mEq/L	$22 - 26$ mEq/L

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

Perform endotracheal intubation and administer exogenous surfactantCevap
B
Administer intravenous sodium bicarbonate to correct the metabolic acidosis
C
Transfer the infant to the radiology department for a computed tomography scan of the chest
D
Initiate immediate intravenous acyclovir for a presumed infectious vesicular eruption
E
Administer empiric intravenous ceftriaxone and vancomycin for early-onset neonatal sepsis

Cevap

The most appropriate next step is to perform endotracheal intubation and administer exogenous surfactant.

The correct approach is to perform endotracheal intubation and administer exogenous surfactant. This premature neonate born at 31 weeks gestation presents with classic Respiratory Distress Syndrome (RDS), characterized by severe respiratory distress, a diffuse reticulogranular ground-glass appearance on radiography, and low lung volumes. The underlying pathophysiology is a deficiency of pulmonary surfactant, leading to high alveolar surface tension, widespread microatelectasis, and profound intrapulmonary shunting. Although continuous positive airway pressure (CPAP) is the preferred initial non-invasive respiratory support for premature infants with RDS, this infant is failing CPAP therapy. Failure is objectively demonstrated by worsening hypoxemia (SpO2 82% on 60% oxygen) and a severe, uncompensated respiratory acidosis (pH 7.18, pCO2 66 mm Hg). When non-invasive ventilation fails (typically defined as a pH < 7.20 with pCO2 > 60 mm Hg, or inability to maintain SpO2 > 90% on high FiO2), the immediate next best step is to secure the airway via endotracheal intubation and administer exogenous surfactant intratracheally to recruit collapsed alveoli and improve gas exchange.

Adım Adım Çözüm

Identify the primary underlying pathology based on the clinical presentation and radiographic findings.

The preterm infant exhibits classic signs of Respiratory Distress Syndrome (RDS) due to surfactant deficiency, confirmed by the ground-glass appearance and air bronchograms on the chest radiograph.

Recognizing the core diagnosis dictates the specific treatment pathway.

Interpret the arterial blood gas to determine the severity of respiratory failure.

The ABG reveals uncompensated respiratory acidosis (pH 7.18, pCO2 66 mm Hg) and hypoxemia (SpO2 82%) despite maximal non-invasive support.

Objective data is required to determine if current interventions are sufficient or if escalation is needed.

Select the appropriate intervention for respiratory failure in the context of RDS.

Endotracheal intubation is required to secure the airway and ventilate the infant, followed by the administration of exogenous surfactant.

Failure of CPAP combined with severe respiratory acidosis is an absolute indication for mechanical ventilation and surfactant replacement to reduce alveolar surface tension.

Anahtar Kavram

Management of severe Neonatal Respiratory Distress Syndrome (RDS)

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

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