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Pulmonary-cardiovascular interaction

Key points The respiratory and cardiac systems are integrally related both anatomically and functionally, and as a result there are significant interactions, particularly in the newborn period. Inappropriately high airway pressure during mechanical ventilation leads to adverse hemodynamic effects including a reduction in left and right ventricular output, a decrease in venous return, and an increase in pulmonary vascular resistance (PVR). Inappropriately low airway pressure can…

Respiratory control and oxygen instability in premature infants

Key points Understanding the physiology of neonatal respiratory control has served as an effective guide to common therapeutic approaches. Both the acute and longer-term consequences of intermittent hypoxemia and apnea of prematurity are subjects of intense interest. Intermittent hypoxemia may contribute to an inflammatory stress response. Although caffeine is the mainstay of apnea therapy, there remains considerable controversy regarding optimal treatment regimens. Innovative newer approaches to…

Newer strategies for surfactant delivery

Key points As fewer preterm infants are managed with an endotracheal tube (ETT) in early life, the usual conduit for surfactant delivery is lacking. With this approach has come a dilemma regarding how and when to deliver surfactant to those showing features of surfactant-deficient respiratory distress syndrome (RDS). Brief intubation solely for surfactant delivery has been widely practiced, but has disadvantages, not the least of which…

Noninvasive respiratory support for preterm infants: An alternative to mechanical ventilation

Key points Continuous positive airway pressure (CPAP) provides effective respiratory support for preterm infants for a range of indications, especially when delivered via binasal prongs or nasal masks at set pressures equal to or greater than 5 cm H 2 O. Extremely preterm infants may be managed with CPAP from the delivery room onward as an alternative to routine intubation and mechanical ventilation. Nasal intermittent positive-pressure…

Ventilator-associated pneumonia

Key points Invasive mechanical ventilation of neonates increases their risk of developing bacterial infection of the lower airways and lung parenchyma, which is termed “ventilator-associated pneumonia” (VAP). VAP is diagnosed on the basis of defined clinical, radiographic, and laboratory criteria. Unlike other neonatal bacterial infections, culture isolation of a single, causative organism is unusual in VAP. Suspected VAP should initially be treated with broad-spectrum antibiotics covering…

Airway microbiome and lung injury

Key points Contrary to conventional teaching, culture-independent molecular techniques have confirmed that the healthy lung is not sterile and the lung microbiome is likely established in early life, influences development of immune responses and pulmonary function, and is altered in disease states. Although the major pathway that microorganisms colonize the uterine cavity is vertical ascension from the vagina, there is emerging evidence suggesting transplacental transfer of…

Vascular development and pulmonary hypertension

Key points Lung vascular development occurs as highly choreographed sequence, regulated by hypoxia inducible factors, vascular endothelial growth factor, nitric oxide, and other transcription factors and mediators. In addition to arterial vessels, pulmonary veins are highly reactive vessels that contribute to the overall regulation of pulmonary vascular resistance in the fetus and newborn. Antenatal pulmonary vascular development can be disrupted by events such as placental insufficiency,…

Respiratory and cardiovascular support in the delivery room

Key points After birth, lung aeration and an increase in pulmonary blood flow are closely linked. Although it is possible to identify deliveries of infants at increased risk of requiring resuscitation, appropriately trained personnel should be present at every birth. Establishing effective ventilation is the key to successful neonatal resuscitation. A very small number of newborns require chest compressions or emergency medications. Routine tracheal suction for…

Perinatal events and their influence on lung development and injury

Key points Multiple antenatal exposures exert effects on the fetal lung—some adverse and other beneficial for postnatal survival. Antenatal exposures can alter lung development and interact with postnatal exposures. Early gestational lung maturation is common and promoted by both antenatal steroids and fetal exposure to inflammation. Antenatal steroid is a common exposure that may interact with postnatal care practices in presently unknown ways. Sepsis with chorioamnionitis…

Critical congenital heart disease: What should the neonatologist know?

Introduction The incidence of congenital heart disease (CHD) is estimated at approximately 8 per 1000 live births, with up to 25–30% of CHD deemed critical congenital heart disease (CCHD). CCHD includes lesions that necessitate early interventions to avoid significant morbidity and mortality and require multidisciplinary subspecialty care from pediatric cardiologists, cardiothoracic surgeons, neonatologists, anesthesiologists, and pediatric cardiac intensivists. Detection of CCHD by prenatal ultrasound (fetal anomaly…

Hemodynamic management in special circumstances

Key points 1. Neonates with hypertrophic cardiomyopathy due to diabetes who have cardiovascular instability benefit from a strategy that avoids positive inotropy and high peak end-expiratory pressure and prioritizes left heart volume loading and increased left ventricular afterload. 2. Neonates with pre-ductal arteriovenous malformations may have flow-mediated pulmonary hypertension and pseudocoarctation physiology if left-to-right ductal shunt (either due to natural decline in systemic vascular resistance or…

Hemodynamic management in resource-challenged countries

Key points Low- and middle-income countries contribute to a major portion of the global neonatal disease burden, accounting for >90% of neonatal mortality. Perinatal asphyxia, gram-negative sepsis, and prematurity are major contributors to the neonatal disease burden in LMIC countries. Understanding the pathophysiology of the underlying disease process is crucial to appropriate hemodynamic management. Hemodynamic management should include an integrated evaluation of the clinical/laboratory parameters, with…

Pathophysiologically based management of pulmonary hypertension of the newborn

Key points Acute pulmonary hypertension (aPH), classically referred to as persistent pulmonary hypertension of the newborn (PPHN) when occurring during the perinatal transition period, is characterized by failure of the normal postnatal decline in pulmonary vascular resistance (PVR). Elevated pulmonary arterial pressure (PAP) may also occur via alternative mechanisms, including left ventricular diastolic heart failure and excessive pulmonary blood flow. Hypoxemia, with or without accompanying systemic…

Chronic pulmonary hypertension

Key points Chronic pulmonary hypertension (cPH), a severe form of pulmonary vascular disease, is characterized by a sustained and progressive elevation of pulmonary vascular resistance, pulmonary artery pressures, and resultant exposure of the right ventricle to high afterload. cPH most commonly affects extreme preterm infants with bronchopulmonary dysplasia (BPD) but has also been identified in preterm infants without overt lung disease. Comprehensive assessment should aim to…

Pathophysiology and assessment of acute pulmonary hypertension of the newborn

Introduction Acute pulmonary hypertension (aPH) in the neonatal period is common in sick newborn infants being treated in the neonatal intensive care unit (NICU). The causes and underlying pathophysiology are multifactorial. Acute pulmonary hypertension in the newborn is secondary to impaired or delayed relaxation of the pulmonary vasculature associated with a diverse group of cardiopulmonary pathologies such as meconium aspiration syndrome (MAS), congenital diaphragmatic hernia (CDH),…

Hemodynamically based management of circulatory compromise in the newborn

Key points There is little outcome-based evidence to guide circulatory support in the newborn. In clinical situations of high risk for circulatory compromise, there are a range of hemodynamics. A “one size fits all” approach to neonatal circulatory support is neither logical nor likely to be successful. It is logical to define the individual hemodynamic in a baby and apply therapy on the basis of those…

Glucocorticoids and adrenal function in neonates with hypotension

Key points 1. Corticosteroids are increasingly used in the acutely ill newborn population to increase blood pressure and reduce inotrope exposure. 2. There are clinical and disease states in infants in which glucocorticoids have been studied and found to have potential benefit. Populations who may respond to corticosteroids include ill term and preterm infants with hypotension and infants with pulmonary hypertension, meconium aspiration syndrome, hypoxic-ischemic encephalopathy,…

Hemodynamics of the neonate following perinatal hypoxic-ischemia and the effects of therapeutic hypothermia

Introduction Globally, neonatal encephalopathy precipitated by perinatal hypoxia-ischemia remains a common cause of brain injury. The incidence varies from 1 to 3 per 1000 to up to 25 per 1000 in developed and developing countries, respectively. Therapeutic hypothermia has been demonstrated to improve both survival and neurological morbidity ; however, there remains a significant burden of mortality and long-term neurological sequelae among survivors. Birth asphyxia, defined…

Assessment and management of septic shock and hypovolemia

Key points Sepsis can progress rapidly from mild clinical signs to full-blown septic shock with high morbidity and mortality. The clinical recognition of the onset of sepsis and the onset of neonatal septic shock can be challenging. In conjunction with the use of comprehensive cardiorespiratory monitoring, early and serial assessment with ultrasound aids in the recognition of the type of septic shock and in the following…

Cardiovascular compromise in the preterm infant during the first postnatal day

Key points The very-low-birth-weight infant is hemodynamically vulnerable due to a unique set of risk factors, which include an immature myocardium with poor response to volume load and afterload, immature autonomic vasoregulation, and thus ineffective cardiovascular compensatory mechanisms, a propensity to develop specific or non-specific inflammatory responses, the imposition of positive airway pressure, systemic-to-pulmonary shunts, and variability in the degree of placental restoration of blood volume…