Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Key Features ++ Onset of symptoms on day 1 of life Hypoxia with poor response to high concentrations of inspired oxygen Right-to-left shunts through the foramen ovale, ductus arteriosus, or both Most often associated with parenchymal lung disease There are three underlying pathophysiologic mechanisms Vasoconstriction due to perinatal hypoxia related to an acute event such as sepsis or asphyxia Prenatal increase in pulmonary vascular smooth muscle development, often associated with meconium aspiration syndrome Decreased cross-sectional area of the pulmonary vascular bed associated with lung hypoplasia (eg, diaphragmatic hernia) +++ Clinical Findings ++ Characterized by onset on the first day of life, usually from birth Respiratory distress is prominent, and PaO2 is usually poorly responsive to high concentrations of inspired oxygen Many infants have associated myocardial depression with systemic hypotension +++ Diagnosis ++ Echocardiography reveals right-to-left shunting at the level of the ductus arteriosus or foramen ovale, or both Chest radiograph may show lung infiltrates related to associated pulmonary pathology (eg, meconium aspiration or hyaline membrane disease) If the majority of right-to-left shunting is at the ductal level, pre- and postductal differences in PaO2 and SaO2 will be observed +++ Treatment ++ First-line therapy includes oxygen and ventilation (to reduce pulmonary vascular resistance) and crystalloid infusions (10–30 mL/kg) to improve systemic pressure Ideally, systolic pressure should be > 50–60 mm Hg With compromised cardiac function, systemic vasopressors can be used as second-line therapy (eg, dopamine, 5–20 μg/kg/min; epinephrine 0.05–0.3 μg/kg/min; or both) Pulmonary vasodilation can be enhanced using inhaled nitric oxide, at doses of 5–20 ppm High-frequency oscillatory ventilation has proved effective in many of these infants, particularly those with severe associated lung disease, by improving lung expansion and recruitment In cases in which conventional therapy is failing (poor oxygenation despite maximum support), extracorporeal membrane oxygenation (ECMO) is used Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.