PPHN

Persistent Pulmonary Hypertension of the Newborn Persistent pulmonary hypertension of the newborn (PPHN), previously referred to as persistent fetal circulation, is a cardiopulmonary disorder characterized by marked pulmonary hypertension that causes right-to-left extrapulmonary shunting of blood and severe hypoxemia and acidemia. It occurs when the newborn’s circulatory system does not have a normal transition after birth. PPHN can occur idiopathically or as a complication of perinatal asphyxia, MAS, maternal smoking, hypocalcemia, maternal obesity, maternal asthma, pneumonia, congenital heart defects, metabolic disorders such as hypoglycemia, hypothermia, hypovolemia, hyperviscosity, acute hypoxia with delayed resuscitation, sepsis, and RDS. It occurs in up to two per 1,000 live births of term, near-term, or post-term infants. As many as one in five pregnant women experience some sort of depressive disorder during pregnancy. Current research findings link a doubled increased risk of developing PPHN to exposure to selective serotonin reuptake inhibitors (SSRIs) (a class of antidepressants) in late pregnancy (Masarwa et al., 2019). Treatment of depression with antidepressants is complicated by the mother’s needs. Careful consideration must be given to the risks, benefits, and alternatives of in utero medication exposure, and these must be discussed with the woman. Pathophysiology Normally, pulmonary artery pressure decreases when the newborn takes the first breath. However, interference with this ability to breathe allows pulmonary pressures to remain increased. Hypoxemia and acidosis also occur, leading to vasoconstriction of the pulmonary artery. These events cause an elevation in pulmonary vascular resistance. Normally, the decrease in pulmonary artery pressure and pulmonary vascular resistance with breathing leads to the closure of the ductus arteriosus and foramen ovale. However, with PPHN, pulmonary vascular resistance is elevated to the point that venous blood is diverted to some degree through fetal shunts (i.e., the ductus arteriosus and foramen ovale) into the systemic circulation, bypassing the lungs, and resulting in systemic arterial hypoxemia. Nursing Assessment Assess the newborn’s status closely. A newborn with persistent pulmonary hypertension demonstrates tachypnea within 12 hours after birth. Observe for marked cyanosis, grunting, respiratory distress with tachypnea, and retractions. Auscultate the heart, noting a systolic ejection harsh sound (tricuspid insufficiency murmur), and measure blood pressure for hypotension resulting from both heart failure and persistent hypoxemia (Stark & Eichenwald, 2020b). Measure oxygen saturation via pulse oximetry and report low values. Prepare the newborn for an echocardiogram, which will reveal right-to-left shunting of blood that confirms the diagnosis. Nursing Management Nursing management focuses on ensuring adequate tissue perfusion and minimizing oxygen demand and energy expenditure. Caring for the newborn with PPHN includes identifying signs and symptoms associated with it which may include murmur, respiratory distress, decreased pulmonary blood flow, hypoxia, hypercarbia, hypoglycemia, cyanosis, metabolic acidosis, and hypotension (a late sign) (Kenner et al., 2019). Usually the newborn is transferred to the NICU for close monitoring. Maintain a neutral thermal environment, including placing the newborn under a radiant warmer or in a warmed isolette to prevent hypothermia. In addition, minimize handling to reduce energy expenditure and oxygen consumption that could lead to further hypoxemia and acidosis. Administer oxygen therapy as ordered via nasal cannula or with positive-pressure ventilation. Monitor oxygen saturation levels via pulse oximetry to evaluate the newborn’s response to treatment and to detect changes. Increased pulmonary pressures associated with PPHN may cause blood to be shunted away from the lungs. The newborn may exhibit uneven pulmonary ventilation, with hyperinflation in some areas and atelectasis in others. This leads to poor perfusion and subsequent hypoxemia, which in turn may increase pulmonary vasoconstriction and a worsening of hypoxemia and acidosis. Blood is diverted to some degree through fetal structures such as the ductus arteriosus or foramen ovale, causing them to remain open, leading to a right-to-left shunting of blood into the systemic circulation. This diversion of blood bypasses the lungs, resulting in systemic arterial hypoxemia. When caring for the newborn with persistent pulmonary hypertension, pay meticulous attention to detail, with continuous monitoring of the newborn’s oxygenation and perfusion status and blood pressure. The goals of therapy include improving alveolar oxygenation, correcting hypovolemia and hypotension with the administration of volume replacement and vasopressors, and anticipating the use of ECMO when support has failed to maintain acceptable oxygenation (Martin et al., 2019). Provide immediate resuscitation after birth and administer oxygen therapy as ordered. Early and effective resuscitation and correction of acidosis and hypoxia are helpful in preventing PPHN. Monitor ABGs frequently to evaluate the effectiveness of oxygen therapy. Provide respiratory support, which frequently necessitates the use of mechanical ventilation. Administer prescribed medications, monitor cardiopulmonary status, cluster care to reduce stimulation, and provide ongoing support and education to the parents. TAKE NOTE! Almost any procedure, such as suctioning, weighing, changing diapers, or positioning, can precipitate severe hypoxemia due to the instability of the pulmonary vasculature. Therefore, minimize the newborn’s exposure to stimulation as much as possible.