A Preterm Infant with an Unlucky Airway

A 1-day-old infant estimated at 29 weeks and 6 days’ gestational age presents with positional respiratory distress.A 36-year-old gravida 5 para 4 woman is referred to the fetal care center because of multiple anomalies noted on routine prenatal ultrasonography.Prenatal maternal serologies are unremarkable.Fetal findings are notable for bilateral ventriculomegaly, a multicystic dysplastic right kidney, an absent right radius, a single umbilical artery, and short fetal long bones.Fetal echocardiography reveals anteriorly malaligned ventricular septal defect with an overriding aorta and right aortic arch.Findings are thought to be consistent with VACTERL (vertebral anomalies, anorectal anomalies, cardiac anomalies, tracheoesophageal fistula or atresia, renal anomalies, and limb anomalies) association. Amniocentesis and whole exome sequencing are unrevealing.Pregnancy is also complicated by chronic hypertension treated with labetalol, and hypothyroidism treated with levothyroxine.The patient is diagnosed with preeclampsia with severe features at 29 weeks and 6 days’ gestation.The woman is admitted to the hospital and receives 1 dose of betamethasone for fetal lung maturation.Cesarean delivery is scheduled because of continued severe range blood pressures and breech positioning of the fetus.A preterm female infant is born at 29 weeks and 6 days’ gestation.The infant emerges with poor tone, apneic, and a heart rate <100 beats/min. The infant is given positive pressure ventilation but develops respiratory distress; thus, she is intubated without difficulty 90 seconds after birth, with improvement in oxygen saturations and heart rate.Apgar score is 1 and 7 at 1 and 5 minutes, respectively.Temperature: 97.7°F (36.5°C)Heart rate: 129 beats/minRespirations: 46 breaths/minBlood pressure: 87/71 mm HgOxygen saturation: 96%Mechanical ventilation settings: Pressure-regulated volume control, tidal volume 7.6 mL (5.5 mL/kg), positive end-expiratory pressure of 5 cm H2O, respiratory rate of 55 breaths/min, and fraction of inspired oxygen (Fio2) 0.25.Birthweight: 1,410 g (55th percentile)Length: 36.8 cm (26th percentile)Head circumference: 32.3 cm (>99th percentile)Head: Macrocephaly with splayed sutures, anterior fontanelle open, soft but fullEyes: Normally spaced, open spontaneouslyLungs: Intermittent respiratory distress with deep subcostal retractions and tracheal tugging, improves with positioning (supine, chin left, mild left head tilt), breath sounds bilaterallyCardiovascular: Regular rate and rhythm, no murmur, adequate lower extremity pulses, normal capillary refillAbdomen: Soft, nontender, nondistended; 2-vessel cordGenitourinary: Female, appropriate for gestational age, concern for rectovaginal fistulaRectal: Imperforate anusExtremities: Missing digit on the right hand, right upper extremity underdeveloped compared with left upper extremityNeurologic: Awake, appropriate tone, and reactivitySkin: Pink, no rashChest radiograph (Fig 1)Magnetic resonance imaging of the brain (Fig 2)The infant’s respiratory status was tenuous and extremely positional, requiring midline position, chin lift, and mild left head tilt to maintain adequate tidal volumes. A follow-up chest radiograph obtained at 36 hours of age showed complete opacification of the right lung fields (Fig 3). Echocardiography confirmed a muscular ventricular septal defect and showed the left pulmonary artery (LPA) arising from the right pulmonary artery.Respiratory distress syndrome with right-sided atelectasisVascular ringRight pulmonary hypoplasiaOtolaryngology was consulted because of recurrent difficulty in ventilation, particularly with changes in positioning, raising concern for airway narrowing, potentially secondary to the LPA sling. At 2 days of age, her endotracheal tube was upsized from 3.0 to 3.5 to allow for bronchoscopy, which revealed a patent but narrow left mainstem bronchus, and the right mainstem bronchus could not be visualized (Fig 4).After bronchoscopy, the patient underwent chest computed tomography angiography (CTA) to better visualize the right mainstem bronchus and right lung. CTA confirmed an LPA sling, complete tracheal rings, and a horseshoe lung connected by a thin isthmus of lung parenchyma. The hypoplastic right lung comprised a single lobe, which was supplied by a small single right lobar artery, a single right pulmonary vein, and a single right lobar bronchus that arose from the left lower lobe bronchus (Fig 5).The infant received nothing by mouth, with a nasogastric tube to low-intermittent suction and total parenteral nutrition via an umbilical venous line. At 3 days of age, the infant underwent a reservoir placement for the hydrocephalus. During the following week, she required reservoir taps every other day for continued ventriculomegaly noted on head ultrasonography. Throughout her hospital course, she continued to struggle with oxygenation and ventilation, with Pco2 levels between 60 and 80 mm Hg (7.9 and 10.64 kPa) despite full ventilatory support, with pressure regulated volume control and settings of tidal volume of 6 mL, positive end-expiratory pressure of 6 cm H2O, respiratory rate of 60 breaths/min, and Fio2 between 0.7 and 1. Difficulty in oxygenation and ventilation was attributed to her complex airway anatomy.The infant was seen by a pediatric geneticist, who hypothesized that many of her anomalies were consistent with VACTERL association. Although the result of prenatal whole exome sequencing was negative, additional genetic testing was ordered, including rapid genome and mitochondrial sequencing. The result of the rapid genome sequencing was negative, but mitochondrial sequencing revealed a pathogenic variant in the mitochondrially encoded tRNA isoleucine (ie, MT-TW) gene. Given the patient’s weight and multiple congenital anomalies, the decision was made by the family and medical team that she was not a candidate for surgical intervention for her LPA sling. As a result of her poor prognosis, her parents made the loving decision to transition to comfort care, and she underwent extubation on a compassionate basis at 11 days of age.Horseshoe lung is a rare congenital lung anomaly in which an isthmus of pulmonary parenchyma extends from the right lung base to the left lung base. (1) The isthmus of lung tissue courses behind the pericardium as it travels across midline, resembling a traditional horseshoe. (1) Most known pediatric cases present with recurrent respiratory distress, recurrent respiratory infections, or failure to thrive in the first year of age prompting further evaluation and imaging. (1)(2) During evaluations of affected patients, lung hypoplasia becomes evident with the incidence of right pulmonary hypoplasia greater than left pulmonary hypoplasia. (1)(2) Unilateral lung opacification can also be seen on chest radiography. (1)(2) The diagnosis of horseshoe lung is often confirmed with CTA and bronchoscopy.Horseshoe lung, when present, is often associated with cardiovascular anomalies, most commonly Scimitar syndrome (80%–85%). (1)(2) Scimitar syndrome consists of anomalous venous drainage of the right lung into the inferior vena cava, right lung hypoplasia, and congenital heart disease. It receives its name from a Turkish sword, scimitar, which is the appearance of the anomalous pulmonary vascular drainage observed on CT. (3) Although horseshoe lung is not a common finding associated with VACTERL association, this combination has previously been reported in the literature. (4)There is no consensus on the care of neonates with horseshoe lung given the rare number of cases reported. In the literature, management has varied from supportive respiratory management, treatment of associated congenital anomalies (particularly cardiac anomalies), and surgical intervention. (1)(2)(5) Overall, multidisciplinary management tailored to each patient is essential.Most term infants with an ultimate diagnosis of horseshoe lung present with recurrent respiratory distress or infection in the first year of age.Horseshoe lung is a rare condition, but when present, it is often associated with Scimitar syndrome. (1)(2)Approximately 25% of cases are associated with cardiovascular anomalies, (2) and screening echocardiography is recommended.American Board of Pediatrics Neonatal-Perinatal Content SpecificationsKnow the clinical features of an infant with airway obstructionPlan appropriate diagnostic evaluation and management for an infant with airway obstructionKnow how age at presentation (in utero, neonate, infancy, or later) affects the differential diagnosis of the clinical presentation of genetic disordersRecognize the diagnostic implications of single versus multiple anomalies