RT Book, Section A1 Malcolm, William F. SR Print(0) ID 1105545411 T1 Congenital Diaphragmatic Hernia T2 Beyond the NICU: Comprehensive Care of the High-Risk Infant YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 978-0-07-174858-2 LK accesspediatrics.mhmedical.com/content.aspx?aid=1105545411 RD 2024/03/29 AB DefinitionPresence of abdominal contents in thoracic cavity during fetal life results in acute neonatal respiratory distress.Often the sickest infants in the NICUAssociated with long-term respiratory, gastrointestinal, and neuro-cognitive difficultiesIncidenceEstimated to occur in one per 3000 live births (true incidence unknown)“Hidden mortality”—early deaths among severely affected fetuses and infantsPathophysiologyAbnormal or incomplete formation of diaphragm between weeks 8 and 10 of gestation allows herniation of abdominal contents into chest cavity, impairing proper lung growth and development (Figure 31-1).Occurs at critical stage of lung embryogenesis, during pulmonary artery and bronchial branchingSubsequent pulmonary parenchymal and vascular hypoplasia with fewer airways, vessels, and alveolar structuresLung hypoplasia most significant on ipsilateral side, contralateral lung also affectedEpidemiology: Three CDH subtypes based on location of diaphragmatic defectBochdalek: posterolateral diaphragmatic defect (most common)Morgagni: anterior diaphragmatic defectPars sternalis: central diaphragmatic defectAdditional facts about CDH85% occur on left side, 13% occur on right, 2% bilateral absence of diaphragm (universally fatal)Right-sided defects associated with higher mortality due to presence of liver in chestCan be isolated finding (50% to 60%) or occur as part of syndrome∼1/3 associated with cardiac, renal, gastrointestinal, or central nervous system anomaliesOverall survival ranges between 50% and 80% for isolated CDHLower survival rates if other anomalies presentRisk factorsNone proven, many postulatedGenetic factorsMaternal nutritional deficiency during pregnancyDisturbances in retinoid-signaling pathway during organogenesisClinical presentationSigns and symptomsMost present with respiratory distress and cyanosis soon after birth.Intestines dilate with swallowed air and compromise cardiorespiratory function.Physical examination: Scaphoid abdomen, barrel-shaped chest, increased work of breathing.Auscultation: Decreased aeration over ipsilateral chest, displacement of heart tones, bowel sounds appreciated in chest.Imaging: Radiography shows gas-filled loops of bowel in chest, displacement of heart, and mediastinum to right (left-sided) (Figure 31-2).Condition variabilitySeverity of respiratory distress corresponds to degree of pulmonary hypoplasia (related to timing and degree of compression of fetal lungs).Mild: May not present until later in newborn course or early infancySevere or unrecognized: Swallowed air following delivery results in intestinal distention, leads to worsening mediastinal shift, compromised venous return, hypoperfusion, and systemic hypotensionDiagnosisPrenatal: Most cases identified antenatally between 16 and 24 weeks' gestation.Characteristic findings on ultrasoundFluid-filled stomach detected in chest cavityPolyhydramniosSmall abdominal circumferenceMediastinal or cardiac shift away from side of herniaPostnatal: Chest radiography shows multiple gas-filled loops of bowel in thorax (Figure 31-2).ManagementAntenatalMedicalDetailed anatomic ultrasonography to detect other anomaliesAmniocentesis for chromosomal studiesDetermination of liver position and lung-to-head ratio to assess degree of pulmonary hypoplasia and predict outcomeParental counselingExpectant management, close monitoring for development of complicationsInduction of labor ∼38 weeks' gestation at tertiary care centerSurgicalMany trials of fetal surgery to correct diaphragmatic defect and promote fetal lung growthDisappointing results due to increased rates of preterm delivery; none have demonstrated significant benefit compared with standard therapyPostnatal (Table 31-1)MedicalResuscitation and stabilizationImmediate postnatal endotracheal intubation (avoid bag-valve-mask ventilation)Nasogastric tube to continuous suctionPre- and post-ductal pulse oximetryCentral venous and arterial accessPlain films of chest and abdomenMaintain quiet environment, consider sedation and paralysisVentilationGoal: Use lowest possible peak pressure to allow adequate gas exchange while avoiding hypoxemia and acidemia (strategy of permissive hypercapnia).Consider early use of high-frequency jet or oscillatory ventilation, ECMO for rescue.OxygenationAdminister supplemental oxygen.Trial ...