RESUSCITATION OF THE NEWBORN: SPECIAL CIRCUMSTANCES
Key Points
• Certain conditions require specific resuscitative measures.
• Antenatal diagnosis can help optimize preparation and management.
• Communication with the family before and after delivery can ease the shock of significant neonatal abnormalities.
Background
In a number of circumstances and diagnoses, independent of neonatal asphyxia, specific resuscitative measures should be undertaken for the newborn infant that fall outside of the usual neonatal resuscitation guidelines and may require additional equipment and technical skills. Given the ever-increasing accuracy of antenatal diagnosis, many of these problems may be anticipated in advance; thus, attention to the management of many uncommon problems is appropriate. This chapter reviews some of these special circumstances and outlines specific treatment recommendations.
Meconium-Stained Amniotic Fluid
Background
• Meconium is a viscous substance from the fetal intestinal tract consisting of water, lanugo, desquamated fetal intestinal cells, skin cells, vernix, amniotic fluid, pancreatic enzymes, and bile pigment.
• It is present in the amniotic fluid in 10% of all pregnancies and in 30% to 40% of post-term infants at delivery.
Epidemiology
• Meconium staining of amniotic fluid (MSAF) occurs in approximately 8% to 25% of all births, primarily in situations of advanced fetal maturity or fetal stress (1).
• Risk factors for MSAF include postmaturity (gestational age beyond 41 weeks), small for gestational age (SGA), fetal distress, and compromised in utero conditions including placental insufficiency and cord compression (2).
• Meconium aspiration syndrome (MAS) is defined as respiratory distress in an infant born through MSAF whose symptoms cannot be otherwise explained. It occurs in 5% of patients born through MSAF (3).
• An estimated 25,000 to 30,000 cases and 1000 deaths related to MAS occur annually in the United States with many more cases in developing countries (1). The incidence of MAS had decreased recently secondary to a decrease in number of deliveries beyond 41 weeks’ gestation in developed countries (4).
• Previously, differentiating thin versus thick meconium was used to guide management decisions, but current Neonatal Resuscitation Program guidelines do not differentiate between the two consistencies (5).
Pathophysiology
• Meconium aspiration causes injury to lung tissues through a variety of mechanisms including complete or partial obstruction of airways, sepsis, inflammation, complement activation and cytokine production, inhibition of surfactant synthesis and function, apoptosis of epithelial cells, and increased pulmonary vascular resistance (3).
• Controversy exists as to whether meconium-stained amniotic fluid always indicates some degree of asphyxia. Meconium-stained fluid alone generally does not indicate asphyxia; however, in the presence of other indications of fetal compromise, its presence is a marker of fetal distress (6).
• MAS may be fatal and often requires aggressive neonatal care, including treatment with extracorporeal membrane oxygenation (ECMO).
Prevention
• Obstetric: The usual methods of assessing fetal well-being should be used to determine the optimal timing and method of delivery.
• Amnioinfusion: In clinical settings with standard peripartum surveillance, the evidence does not support the use of amnioinfusion for MSAF. In settings with limited peripartum surveillance (developing countries), where complications of MSAF are common, amnioinfusion appears to reduce the risk of MAS (7).
• Antepartum suctioning: Suctioning of the oropharynx upon delivery of the head and before delivery of the shoulders is used commonly in obstetric practices to decrease the possibility of meconium aspiration with the first breath. A multicenter, randomized, prospective study concluded that antepartum suctioning does not decrease the incidence of MAS even in high-risk infants. On the contrary, it may lead to complications including bradycardia, desaturations, and increased incidence of pneumothorax (8).
• Neonatal
• If the infant has respiratory depression, a heart rate less than 100 beats per minute (bpm), or hypotonia, the infant should be rapidly intubated to clear the airway of meconium (5).
• Gregory et al. (9) found that 9% of infants who had no meconium in the pharynx after obstetrical suctioning had meconium below the vocal cords in the trachea; therefore, visualization of the cords without intubation is insufficient.
• The procedure for intubation is as follows:
The infant is placed on a radiant warmer.
Before any other resuscitative measures are begun, the infant is intubated under direct visualization using a laryngoscope (No. 0 or 1 blade) with the largest appropriate endotracheal tube (usually, a 3.5 or 4.0 tube for a term infant).
Suctioning of the pharynx during this procedure with a large suction catheter may be needed to visualize the airway.
Once the infant is intubated, a suction device is quickly attached directly to the hub of the endotracheal tube, suction is applied, and the tube is slowly removed, clearing meconium from the trachea.
If meconium is obtained from below the vocal cords, this intubation and suctioning procedure should be repeated until no further meconium is obtained.
To decrease the possibility of hypoxia while intubating and suctioning, blow-by oxygen should be administered at the patient’s mouth.
• Duration of tracheal suctioning:
If repetitive intubation is difficult or if multiple intubations continue to yield meconium, one reaches a point at which continual depression of the newborn becomes a greater concern than does complete removal of meconium.
Clinical judgment, especially the presence of bradycardia, can guide the timing of initiation of manual ventilation.
Usually, after 2 to 5 minutes of intubation and suctioning, or if sustained bradycardia less than 60 bpm occurs, standard resuscitative measures should be considered.
• When not to intubate:
Randomized controlled trials do not support routine use of endotracheal intubation at birth in vigorous meconium-stained babies to reduce mortality or MAS (1,10).
If a vigorous infant with thick meconium is not initially intubated but later becomes distressed, intubation and removal of meconium from the airway may be necessary.
• Gastric suctioning:
Although many clinicians routinely suction out the stomach contents when meconium is noted in the amniotic fluid, there is no evidence to support this practice (11).
Management
• The respiratory manifestations include increased work of breathing, tachypnea, and cyanosis.
• Fifteen to twenty percent of infants with the MAS develop persistent pulmonary hypertension of the newborn (PPHN). Pneumothorax and pneumomediastinum are common complications in infants with severe MAS.
• Management consists mainly of supportive respiratory and cardiovascular care with options for oxygen therapy, conventional or high-frequency mechanical ventilation, vasopressors, inhaled nitric oxide, surfactant therapy, and ECMO.
• No specific long-term deficits in pulmonary function have been attributed to MAS. The ultimate prognosis depends not so much on the pulmonary disease as on the accompanying asphyxial insult and treatment required (3).
Pneumothorax
Background
Definition
• Pneumothorax is a collection of free gas in the thorax between the visceral and parietal pleura, which may compromise respiratory function.
• A pneumothorax can progressively increase in volume, leading to a shift of the mediastinal structures, known as a tension pneumothorax.
Pathophysiology
• Uneven ventilation in the lung and partial airway obstruction, especially when coupled with positive-pressure ventilation, can lead to overdistention and rupture of alveoli, with leakage of air into the pleural space and accumulation of gas.
• As gas accumulates under pressure, collapse of the lung, a shift in mediastinal structures, and decreased cardiac output resulting from decreased venous return can lead to acute deterioration.
Epidemiology
• Pneumothorax is estimated to occur in 1% to 2% of all term births, usually without symptoms (3).
• It is seen more frequently in infants with pulmonary disease and transient tachypnea of the newborn (10%), respiratory distress syndrome (5% to 20%), and MAS (20% to 50%).
Associations
• Pneumothorax is often seen with pulmonary disease, especially if positive-pressure ventilation with high pressures is used.
• Other air leaks (pneumomediastinum, pneumopericardium, subcutaneous emphysema, even pneumoperitoneum) may be seen in patients with pneumothorax.
• Pneumothorax is very common in patients with pulmonary hypoplasia (discussed later in this chapter).
Evaluation
History and Physical
• The infant may be asymptomatic.
• Often, a sudden deterioration, with cyanosis, bradycardia, and hypotension, is seen.
• A shift in cardiac sounds or change in breath sounds may occur.
Laboratory Tests
• Diagnosis may be made by transillumination, which reveals increased light transmission through the affected hemithorax.
• Usually, a chest radiograph will definitively diagnose a pneumothorax, but if the patient is deteriorating, treatment should be started based on a positive transillumination, without delay.
Treatment
• If asymptomatic, no treatment is needed. Careful observation is usually sufficient, and the pneumothorax will likely resorb.
• Mildly symptomatic pneumothorax with only modest oxygen requirements, tachypnea, and normal blood gases should be followed closely.
• Nitrogen washout: Placing the infant in 100% oxygen may facilitate resorption of a pneumothorax, but this management strategy has not been studied in infants. Considering the risks of oxygen toxicity and absorption atelectasis, this intervention is best avoided in all infants. It should be especially avoided in premature infants because of the association of hyperoxia with retinopathy of prematurity.
• Symptomatic pneumothorax may be treated emergently by tapping the pleural space anteriorly using a needle, aspiration kit, or Angiocath catheter.
• It is usually necessary to place a chest tube after this procedure.
• Insertion of a polyvinyl chloride chest tube, usually 10 or 12 French, in the fourth intercostal space in the anterior axillary line and aimed anteriorly, is the preferable method for treating symptomatic pneumothorax.
Complications
• Prognosis is generally good but depends on the underlying pulmonary disease.
• Pneumothorax is associated with an increased incidence of intraventricular hemorrhage in premature infants.
Congenital Diaphragmatic Hernia
Background
Definition
• The presence of normally intra-abdominal organs in the thorax via a defect in the diaphragm.
• The diagnosis of congenital diaphragmatic hernia may be known from antenatal ultrasonography or may be suspected clinically.
Etiology
• Failure of the Bochdalek foramen to close at 8 to 10 weeks of gestation allows the bowel to migrate into the thoracic cavity.
Pathophysiology
• The presence of the intestines and other organs in the chest can impair lung growth in utero. This leads to pulmonary insufficiency and PPHN secondary to pulmonary hypoplasia, lower number of alveoli, and airway and vascular muscular hypertrophy (3).
Epidemiology
• Incidence is 1 in 2500 to 1 in 4000, with 90% on the left; 56% of cases are prenatally diagnosed (12).
• Over the last 10 to 15 years, average survival for Congenital Diaphragmatic Hernia (CDH) has improved from 50% to 70% to 80% and as high as 90% in some institutions (13). Poor outcomes are associated with large defects, presence of liver in the chest, earlier displacement of abdominal contents into the chest, and lung area to head circumference ratio (LHR) less than 1—all indicators of the severity of the pulmonary hypoplasia.
Evaluation
History and Physical
• Clinical findings that may be present include
• Scaphoid abdomen
• Shift in heart sounds to the right
• Unequal breath sounds
• Respiratory distress
• Note that commonly there may be no symptoms other than respiratory distress.
Laboratory Tests
• A chest radiograph showing abdominal organs in the thorax confirms the diagnosis.
Treatment
Initial Management
• If the diagnosis is suspected prenatally, the mother should be counseled about the potential need for ECMO and offered delivery in a tertiary center with that capability (12).
• Avoid bag and mask ventilation and immediately intubate and begin manual ventilation because face mask ventilation may lead to gaseous distension of the intestines, further compressing the lungs. An orogastric tube should be placed to evacuate the stomach.
• The infant should be transferred to a tertiary neonatal intensive care unit (NICU) for further management.
NICU and Surgical Management
• Standardized, multidisciplinary treatment guidelines that include input from neonatology, pediatric surgery, ECMO specialists, and respiratory therapy are critical to successful management (14).
• Use of strategies aimed at minimizing lung injury (gentle ventilation or permissive hypercapnia), tolerance of postductal acidosis and hypoxemia, and adhering to center-specific criteria for ECMO are strategies most consistently reported by successful centers (12).
• Surgical repair with reduction of the intestines into the peritoneal cavity and repair of the diaphragmatic defect is the definitive treatment.
• Mean age for repair is variable across centers because timing of surgery is dependent on the patient’s clinical condition. Though some studies have revealed no differences in outcomes of infants undergoing early versus delayed repair (15), others show that early repair in the face of unstable cardiorespiratory status may have worse outcomes, and delayed repair may improve survival in patients with borderline prognosis (16). There is no evidence that timing of surgery influences survival (17). Currently, repair is delayed at most centers until the patient’s cardiovascular status is stabilized, and the risk of PPHN is lessened.
Complications
• Factors associated with mortality in CDH are severity of pulmonary hypertension, birth weight, associated defects/anomalies, gestational age at birth, inborn status, and need for ECMO (13).
• ECMO is used in approximately 30% of cases and is associated with a 51% survival. The sickest infants likely require ECMO, and though the overall outcomes are worse, ECMO likely improves survival in these patients (13).
• Infants born with CDH are at higher risk of morbidities such as pulmonary vascular abnormalities causing pulmonary hypertension, obstructive airway disease, gastroesophageal reflux disease requiring surgery, neurodevelopmental delay, chest wall deformities, and scoliosis (3).
• Although fetal surgical interventions such as tracheal occlusion have not been successful so far, minimally invasive techniques such as percutaneous fetoscopic endoluminal tracheal occlusion have shown promise and are currently being investigated in randomized clinical trials (18).
Associations
• CDH is commonly associated with multiple congenital anomalies including cardiac, urogenital, chromosomal, syndromic, and musculoskeletal. The reported incidence of associated malformations varies between 20% and 60% (19).
GASTROINTESTINAL MALFORMATIONS
Omphalocele
Background
Definition
• An omphalocele is a congenital defect in the formation of the umbilical and supraumbilical portions of the abdominal wall.
• Giant omphalocele is defined as an abdominal wall defect larger than 4 cm with the liver partly extruded in the defect (20).
Etiology
• Before 10 weeks of gestation, there is an embryologically normal defect in the anterior abdominal wall.
• If this defect fails to close, a saclike herniation of the peritoneum and abdominal contents through the abdominal wall remains.
Epidemiology
• Omphalocele occurs in 1 in 4000 to 1 in 10,000 births.
Evaluation
History and Physical
• Omphaloceles have the appearance of a transparent sac containing bowel protruding from the anterior abdominal wall.
• Omphaloceles have a large base with the umbilical cord implanted on the sac.
• Rupture of the sac can occur before delivery.
Treatment
Initial Management
• Most studies have concluded that there is no advantage to cesarean delivery for patients with abdominal wall defects (21).
• After delivery, the infant must be immediately placed on the radiant warmer, basic resuscitation performed, and then the defect gently wrapped in warm saline-soaked sterile gauze.
• The entire lower half of the infant should be placed in a sterile “bowel bag.” This minimizes heat and water loss from the bowel and protects the exposed abdominal organs.
• Emergent transfer to a tertiary NICU is necessary for pediatric surgical repair.
Surgical Repair
• For most defects, a primary repair with the bowel being reduced into the peritoneal cavity is the procedure of choice.
• For larger defects, a staged repair, involving suspension of either the native sac or a synthetic silo above the patient, with gradual reduction of the contents, may be employed.
• For giant omphaloceles, a “skin-only” closure leaving a larger ventral hernia that may be repaired later may be needed.
• If the defect is too large for even a skin-only closure, then the sac may be treated with topical antimicrobials and allowed to epithelialize.
Complications
• Prognosis generally depends on the associated anomalies.
• Survival is 70% or better with isolated omphalocele, and recent reviews suggest even greater survival in patients with normal karyotype (22), but omphalocele with accompanying serious cardiac disease has been associated with a mortality of up to 80%.
Associations
• Up to two-thirds of patients with omphaloceles have associated anomalies, including trisomies (30%), cardiac lesions (20%), other gastrointestinal anomalies, and other midline defects such as bladder exstrophy.
Gastroschisis
Background
Definition
• Gastroschisis is the herniation of abdominal contents through an abdominal wall defect without a covering membrane of peritoneum or amnion from the umbilical cord.
• These defects occur on the right side of the umbilicus.
Etiology
• The cause is controversial: rupture of a hernia of the umbilical cord at the site of involution of the right umbilical vein versus interruption of the omphalomesenteric artery.
Epidemiology
• The incidence of gastroschisis varies from 1 to 5 per 10,000 live births and is similar in male and female fetuses. Worldwide, the prevalence of gastroschisis has increased two- to threefold in the past three decades (23,24).
• Risk factors for gastroschisis include young maternal age, lower socioeconomic status, and exposure to external agents such as vasoconstricting decongestants, nonsteroidal anti-inflammatory agents, cocaine, and possibly pesticides/herbicides (3).
Evaluation
History and Physical
• The abdominal defect is usually small, but it may have a large amount of abdominal contents present outside of the peritoneal cavity, with the potential for vascular occlusion.
• No covering membrane is present, although a fibrous material adherent to the intestines may be seen.
Treatment
• Management is the same as for omphalocele, but repair is more urgent.
Complications
• Gastroschisis has a mortality rate of 10% to 30%.
• Establishment of enteral feedings is usually a slow process. Exclusive human milk feeding after gastroschisis repair has been shown to decrease time to achieve full enteral feeds and time to discharge (25).
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
