Andersons pediatric cardiology 1842

In addition to ductal restriction, one etiology of shock in a neonate with a fUVH with ductal-dependent systemic blood flow deserves special mention The neonate with hypoplastic left heart syndrome and a restrictive atrial septum (usually less than 2 to 3 mm) who will appear well in the first few hours of life But as PVR falls and left atrial hypertension progresses, such a neonate will develop tachypnea, hypoxemia, and eventually hypotension, low cardiac output, and shock This physiology requires emergent catheter-based or surgical atrial decompression In our experience, an unrestrictive atrial septum and low PVR as causes of shock preoperatively are rare In the few days after birth, symptoms of congestive heart failure (tachypnea, tachycardia, hepatomegaly) may occur; however, circulatory collapse is exceedingly unlikely In babies with a more indolent picture of congestive heart failure, manipulation of the PVR to mimic the fetal circulation is sometimes undertaken with subatmospheric oxygen by using nitrogen blended with room air to induce hypoxic pulmonary vasoconstriction) More invasive strategies including intubation, sedation, paralysis, and hypoventilation with hypercapnia or inspired carbon dioxide have also been used.46,47 However, we generally recommend that babies with surgical heart disease do not undergo extensive medical management—babies with early symptoms generally undergo an early first- stage operation, whereas those with circulatory collapse undergo bilateral pulmonary artery banding (with either a stent or prostaglandin to maintain ductal patency) The presentation of the neonate with a multidistribution physiology (see Chapter 70) can be quite varied, as discussed earlier The anatomy and physiology must be delineated and an assessment made of the determinants of VO2 and DO2 in order to identify next steps in management Role of Positive-Pressure Ventilation in the Neonate With a Multidistribution Circulation and Shock Noninvasive and invasive positive airway pressure may be used to recruit lung volume and improve oxygenation (continuous positive airway pressure and positive end-expiratory pressure, respectively) and provide ventilatory assistance (bilevel positive airway pressure [BiPAP] and tidal volume ventilation, respectively) In addition, mechanical ventilation unloads the respiratory pump, allowing for the redistribution of a limited Qs to other vital organs.47a Under normal conditions, respiratory muscle VO2 is a small fraction of global VO2 Accordingly, the respiratory pump receives less than 5% of total CO However, as respiratory work increases—due to metabolic acidosis–induced hyperventilation, for example, or impaired respiratory mechanics—respiratory muscle VO2 may approach 40% to 50% of total body VO2 When this occurs and CO is limited, respiratory pump perfusion may occur at the expense of other vital organs, including the brain.47b Also, in the neonate with an increased minute ventilation and work of breathing, by eliminating exaggerated negative intrathoracic pressure (ITP) and increasing ITP above atmospheric with positivepressure ventilation (PPV), afterload for the systemic ventricle decreases significantly (ventricular systolic transmural pressure decreases).47c The net effect of these changes is a marked improvement in the respiratory, myocardial, and global VO2-DO2 relationship In summary, intubation and PPV is helpful in neonates—usually with a postnatal diagnosis—who present with low systemic blood flow and/or circulatory collapse, whereas “elective” PPV (1) is usually not indicated and (2) can increase surgical risk and contribute to hospital morbidity (see earlier) Nursing Considerations and Family Support (See Also Chapter 82) Nurses at the bedside of this particularly tenuous patient population must be mindful of the impact of routine care on DO2/VO2 balance, and individual items should be clustered whenever possible When patients present in shock, nonessential care should be limited to avoid excessive VO2 in the setting of inadequate DO2 Admission of a neonate to a specialized intensive care unit requires attention to and support from the entire family, particularly in the case of complex CHD when surgery is expected in the neonatal period Both acute and posttraumatic stress disorders are common, having both short- and long-term implications for the family and the neonate In a meta-analysis of over 37,000 healthy mothers (of healthy infants), the prevalence of postpartum depression ranges from 8% (Europe) to 26% (Middle East) and is considered the most common complication of pregnancy.48 The prevalence of short- and long-term depression in mothers of infants with CHD has been reported much more frequently than that in fathers and, not surprisingly, the rate of significant maternal depression is higher than that in controls.49–55 In addition, the frequency is higher in mothers whose children have more complex CHD, such as those with a fUVH versus milder forms of CHD The recognition of maternal anxiety and depression is particularly important for the bedside staff, so that adequate support and referrals may be made With the increasing prevalence of prenatal diagnosis, the timing of this initial support has shifted from the CICU to the fetal heart programs; nonetheless, the reality of the upcoming surgery and impending threat to the infant's survival may be overwhelming Even families who are well supported through diagnosis in the prenatal period are likely to require high levels of continued support following birth, as the severity of the diagnosis is often fully realized only once the child has been born Challenges include family and marital stress, sibling mental health, financial considerations, and much more beyond the scope of this chapter It is important for the entire care team, in particular the bedside nurse, to be aware of these short- and long-term challenges Efforts to facilitate parental bonding should be considered a routine part of care in the preoperative period Holding of the infant, particularly skin to skin, should be recommended and encouraged unless contradicted by clinical status Parents should be proactively engaged in bedside care and empowered to ask clarifying questions when the plan of care is being discussed with the medical team Finally, an important component of preoperative support and education is to prepare the family as well as possible for the visual appearance of a neonate following cardiac surgery.56–58 Although the medical and nursing staff are quite familiar with all of the medical equipment, drainage catheters, monitors, and so on, the shock of the appearance of the baby in the middle of all this technology can be overwhelming Delayed sternal closure, in particular, should be discussed, and pictures made available if possible.59 Feeding and Nutritional Challenges The nutritional status of the neonate should be assessed prior to palliating the neonate with a fUVH Feeding prior to surgery remains controversial The risk of impaired systemic perfusion leading to necrotizing enterocolitis may outweigh the benefit of enteral feeding However, several studies have indicated that initiation of preoperative enteral feeds improves oral-motor coordination, decreases infection rates, and prevents bacterial translocation.60–64 Unless there is profound evidence of inadequate DO2 or an anatomic gastrointestinal comorbidity, most centers will allow the preoperative neonate with single-