Walsh: Perinatal and Pediatric Respiratory Care, 3rd Edition

Chapter 27: Neonatal Pulmonary Disorders

Answers to Assessment Questions and Clinical Scenarios

1.	A
Rationale: Occurring in 60% of infants born at less than 28 weeks of gestation, deficient surfactant production or deficient release of surfactant into the immature respiratory alveoli results in an increase in surface forces and lung elastic recoil. Coupled with the extremely compliant chest wall of the preterm infant, this leads to reduced alveolar recruitment (known as atelectasis). This condition is characterized by decreased functional residual capacity (FRC), decreased pulmonary compliance, increased pulmonary resistance, and ventilation–perfusion mismatch, and results in hypoxia, hypercarbia, and respiratory acidosis.
2.	D
Rationale: Classic indications for endotracheal intubation and mechanical ventilation occur if the infant requires greater than 80% oxygen with a CPAP of 8 cm H2O, if there is increasing hypercarbia with respiratory acidosis, or if apneic episodes become prolonged. Some patient care protocols are less tolerant, with intubation, surfactant, and subsequent ventilation occurring at a much lower threshold.
3.	B
Rationale: The infant with transient tachypnea of the newborn (TTN) may be mildly depressed at birth with fairly good Apgar scores. Tachypnea (60 to 150 breaths/min), cyanosis, grunting, retractions, and nasal flaring begin within a few hours. ABG analysis reveals mild to moderate hypoxemia, hypercapnia, and respiratory acidosis. The chest radiograph shows pulmonary vascular congestion, prominent perihilar streaking, fluid in the interlobular fissures, hyperexpansion, and a flat diaphragm, which is why it is sometimes referred to as wet lung syndrome.
4.	D
Rationale: When an infection is acquired postnatally, the radiographic findings often change from normal to severely abnormal over the first few days. Depending on the severity of the disease process and required treatment, pleural effusions, pulmonary edema, pneumatoceles, cardiomegaly, and evidence of barotrauma may be seen. ABG values reveal hypoxemia that is refractory to oxygen therapy and hypercarbia that responds poorly to ventilatory efforts. Metabolic acidosis may develop as infection becomes more severe.
5.	C
Rationale: Group B Streptococcus has emerged as a predominant pathogen in neonatal pneumonia; it presents a serious threat to the newborn and is acquired during labor. Obstetric complications have been implicated in 50% to 80% of infants with early-onset group B streptococcal pneumonia, indicating intrauterine infection; this infection occurs most often in very low birth weight infants. Early-onset pneumonia from group B Streptococcus may progress rapidly to shock or death, and mortality is high (20% to 50%) regardless of treatment. When the onset of group B streptococcal disease is later (2 to 3 wk after birth), the infant may present with meningitis rather than pneumonia.
6.	B
Rationale: Meconium is the green-tinged bowel content of an infant, which is usually passed within 48 hours after delivery. Meconium aspiration syndrome (MAS) is suggested whenever there is meconium staining of the amniotic fluid. The diagnosis of MAS is generally made whenever meconium is visualized at the vocal cords and the infant has clinical signs of respiratory distress.
7.	C
Rationale: Some fetuses may be assessed as “at risk” for MAS, including those with oligohydramnios; abnormal fetal heart rate tracings; and thick, meconium-stained amniotic fluids.
8.	D
Rationale: Persistent pulmonary hypertension of the newborn (PPHN) occurs most often in infants who are term or postterm and is associated with several underlying neonatal clinical conditions, including MAS, RDS, and birth asphyxia; however, it may also be idiopathic with no known cause.
9.	C
Rationale: A number of large randomized, controlled studies have shown that low doses such as 20 ppm iNO improve outcomes and reduce the need for extreme measures such as ECMO.
10.	D
Rationale: Upright positioning; small, frequent feedings of thickened formula; temperature stability; or a combination of these factors may be helpful in reducing apnea of prematurity. Frequently, a low FiO2 of 0.23 to 0.25 is effective in decreasing apneic episodes.