Neonates experiencing respiratory distress present with tachypnea, nasal flaring, and intercostal, substernal, and retrosternal retractions. The chest wall during infancy is composed primarily of cartilage, making the chest wall compliance much greater than that of the lungs. As the resistance and compliance worsen, neonates have to generate higher pleural pressures during inhalation, causing the “floppy” chest wall to collapse inward creating retractions. On exhalation, the neonatal chest wall lacks the necessary recoil to counteract the inward forces of the lungs, and thus the lungs are prone to premature collapse. Infants will attempt to maintain a back pressure in the lungs, to preserve the functional residual capacity, by narrowing the glottis and maintaining respiratory muscle activity (active exhalation). This results in vocalization during exhalation or “grunting,” which is often mistaken for infants’ crying. Grunting can usually be heard without auscultation and is a useful clinical sign of impending respiratory failure. The Silverman Anderson respiratory scoring system is a useful clinical tool to assess the degree of respiratory distress in neonates (Fig. 22-1).

When introduced in 1971, CPAP was touted as the “missing link” because it could provide oxygen treatment while avoiding mechanical ventilation in the neonate.2 Used appropriately, CPAP is a less invasive and less aggressive form of therapy than other forms of ventilatory support. Newborns with retained lung fluid, atelectasis, insufficient surfactant production, or respiratory distress syndrome (RDS) are good candidates for CPAP. Such patients include very low-birth-weight (VLBW) and premature infants.³ CPAP also can be used successfully in infants with respiratory distress arising from other causes, including transient tachypnea of the newborn, meconium aspiration syndrome, primary pulmonary hypertension, pulmonary hemorrhage, paralysis of a hemidiaphragm, and following surgical repair of diaphragmatic hernias and congenital cardiac anomalies, congenital pneumonias, respiratory syncitial virus (RSV) bronchiolitis, apnea of prematurity, and congenital and acquired airway lesions.⁴

Box 22-1 lists the indications for CPAP in neonates originally established by the American Association for Respiratory Care (AARC).⁵

Compared with standard oxygen therapy, CPAP reduces grunting, and tachypnea, increases FRC and arterial oxygen partial pressure (PaO₂), decreases intrapulmonary shunting, improves lung compliance, aids in the stabilization of the floppy infant chest wall, improves distribution of ventilation, and reduces inspiratory WOB.4 CPAP is believed to reduce the severity and duration of central and obstructive apneas by mechanically splinting the upper airway, promoting better alveolar recruitment, oxygenation, and stimulation of the infant to breath.⁶

Although there is no consensus on how best to manage neonates on CPAP, two general approaches are currently being used to minimize the use of invasive mechanical ventilation and better protect the fragile neonatal respiratory system. Early CPAP involves implementing therapy in the delivery room or neonatal intensive care unit (NICU) only after the infant is stabilized and is effectively breathing on his or her own. This is performed prophylactically even if the neonate is not exhibiting respiratory distress or apnea. The goal is to recruit air spaces and maintain lung volumes early to promote gas exchange and reduce the likelihood that respiratory failure and apnea will occur. This approach is beneficial for premature infants that lack lung surfactant and are at risk for developing atelectasis. Breathing at low lung volumes can result in unnecessary lung injury (atelectotrauma), which can hinder surfactant production. Many premature neonates can be managed successfully using CPAP without ever requiring endotracheal intubation and mechanical ventilation. If the patient does develop respiratory failure, then he or she is intubated, given lung surfactant, and then promptly weaned from the ventilator and extubated. This approach is a drastic departure from the previous approach that has been used over the last 20 years, in which neonates would be intubated and placed on a ventilator for weeks or even months until they were a certain size or weight. Centers that implement early CPAP report a very low incidence of infants developing chronic lung disease or bronchopulmonary dysplasia (BPD) because the lungs are not being subjected to the relatively large inflation pressures that are observed during mechanical ventilation.^7,8 A recent clinical trial in premature neonates demonstrated that this early CPAP approach resulted in less need for intubation and fewer days of mechanical ventilation, and infants were more likely to be alive and free from the need for mechanical ventilation after a week than were neonates intubated for surfactant and supported with mechanical ventilation for at least 24 hours.⁹

Another clinical approach implements elective intubation, prophylactic surfactant administration, short-term lung-protective ventilation, and rapid extubation to CPAP within hours of birth. (NOTE: This approach is also known as InSURE (Intubate, SURfactant, Extubation) and is implemented shortly following birth.¹⁰) The InSURE approach assures that all premature infants will receive at least one dose of surfactant, but it does not eliminate the potential that even short-term ventilation can result in some degree of lung injury. The InSURE approach has been associated with lower incidences of mechanical ventilation, air-leak syndromes, and BPD than an approach that administers surfactant and embraces prolonged mechanical ventilation support.¹¹

The major question that remains is whether these two disparate approaches impact long-term survival and the development of chronic complications (e.g., BPD). Another important outcome related to these different approaches is the incidence of CPAP failure and subsequent ventilation requirements among neonates. Approximately 25% to 40% of infants with birth weights between 1000 and 1500 g may fail early CPAP and require intubation and mechanical ventilation, whereas 25% to 38% of infants with similar birth weights may fail CPAP using the InSURE approach.⁴ Some institutions use a combination of these approaches wherein smaller premature neonates (<28 weeks’ gestational age), with lower surfactant production, will be supported initially using InSURE and all other larger neontates are supported using the early CPAP strategy. Both these strategies strive to minimize invasive mechanical ventilation and have redefined the approach to supporting premature infants at risk for developing respiratory failure. Minimally invasive ventilation strategies, such as CPAP, have likely been a major reason why premature neonates are able to survive at a lower gestational age and with fewer complications than ever before.

Any neonate that has recently been extubated from mechanical ventilation is at risk for developing hypoxemia, respiratory acidosis, and apnea. Extubation to CPAP, regardless of whether surfactant was administered, has been associated with a reduction in the incidence of respiratory failure and the need for additional ventilatory support in neonates.¹²

Infants with certain congenital heart diseases reportedly benefit from CPAP. Cardiac anomalies that increase pulmonary blood flow can reduce lung compliance (C_L) and FRC, thus increasing WOB and worsening hypoxia. The most common defects associated with increased pulmonary blood flow are ventricular septal defects, atrial septal defects, atrioventricular (AV) canal, and patent ductus arteriosus. Positive intrathoracic pressure produced by a CPAP system can mechanically reduce pulmonary blood flow while restoring FRC.^13,14

Use of CPAP is not appropriate and is potentially dangerous in infants who show signs of nasal obstruction or severe upper airway malformation, such as choanal atresia, cleft palate, or tracheoesophageal fistula.¹³ CPAP has been used in patients with bronchiolitis, but its use in these patients has been controversial and may be contraindicated in some cases.^5,15,16 More recent evidence suggests, however, that CPAP can result in favorable outcomes in infants affected with bronchiolitis by reducing carbon dioxide levels and eliminating the need for mechanical ventilation.¹⁷

Patients who have severe cardiovascular instability, severe ventilatory impairment (pH < 7.25, PaCO₂> 60), refractory hypoxemia (PaO₂ < 50 torr on >0.6 F_IO₂), frequent apnea that does not respond to stimulation or intravenous caffeine therapy, or are receiving high levels of sedation may require intubation and mechanical ventilation rather than CPAP.¹³ CPAP or any form noninvasive positive pressure to the airway should not be used in infants with untreated congenital diaphragmatic hernia; these infants should be intubated to prevent gastric insufflations and distention and further compromise of the heart and lungs.¹⁵ Some surgeons discourage the use of CPAP in infants after any surgical procedure involving the gastrointestinal tract.

Most commonly, CPAP is applied via nasal prongs; however, some clinicians prefer to use CPAP in intubated neonates while weaning from mechanical ventilation to observe whether the infant is experiencing apnea. Prolonged support using this approach should be discouraged whenever possible because it is has been associated with increased need for reintubation after the breathing tube has been removed.¹²

Because newborns are obligate nose breathers, nasal CPAP can be applied in several ways. Previously, a short endotracheal tube (ET) was placed into one of the nares and taped to the face to provide nasopharyngeal tube CPAP. A snug-fitting set of short binasal prongs is the most commonly used interface. Neonatal nasal masks are also available and are gaining popularity among some clinicians. It is common practice to alternate between these two nasal airway interfaces. Both devices are effective, but the distending pressure they provide can be lost when the infant cries or breathes through the mouth. Binasal prongs and masks may be more beneficial than a nasopharyngeal tube because they are less invasive and provide the least amount of resistance to gas flow and, hence, lower imposed (or resistive) WOB, and facilitate mobilization and oral feeding.14,18 Additionally, short binasal prongs were found to be more effective than using single nasopharyngeal tube in reducing the rate of re-intubation in premature neonates supported with CPAP.¹⁹

Nasal prongs and masks must be fitted correctly so that they do not leak or cause trauma to the patient. Nasal prongs and masks usually are made of a latex-free material, such as silicone. Molded into a manifold or attached to one, the prongs are placed just inside the infant’s nares (Fig. 22-2). Prongs are available in a variety of sizes. The fit of the prongs is critical; they must fit snugly into the nares but must not be so tight as to cause skin blanching. If a nasal mask is used instead of prongs, it, too, must be carefully selected for proper size and fit. Masks can cause pressure injury to the skin if improperly fitted, and they may not seal if they are too large or small.

The entire CPAP apparatus is stabilized on the patient’s head with headgear or a “fixation” system consisting of a bonnet, cap, or straps (Fig. 22-3). Many commercial system configurations are available. The correct size of straps and head coverings must be carefully chosen and adjusted so that no part of the infant’s head is subjected to squeezing or occlusive pressure points. After the CPAP delivery device has been attached to the CPAP manifold, the CPAP level and F_IO₂ are set. The CPAP system is assessed frequently to ensure effective delivery. The patient’s nose is checked regularly for signs of pressure necrosis, and the prongs must be checked routinely for patency.

The CPAP system functions primarily to regulate gas flow during inhalation and exhalation and to maintain a consistent pressure at the nasal airway opening. The CPAP system consists of five essential components:

Numerous studies have compared differences in gas exchange, WOB, and requirement for (re)intubation with the available CPAP devices; however, it is important to note that no single device has been shown to be superior to another when major outcomes (i.e., mortality and morbidity) in neonates are considered (Key Point 22-1).⁴

Over the last three decades, the most common CPAP system that has been applied noninvasively has been accomplished using a mechanical ventilator. Ventilator CPAP has also been referred to as conventional CPAP in the clinical setting. Ventilator CPAP is convenient because it has traditionally been used following extubation from mechanical ventilation and does not rely on having to use a separate device to apply therapy. Many ventilator manufacturers have designed specific noninvasive CPAP modes into the ventilator platform exclusively for neonates. The clinician can set the CPAP level, and the exhalation valve regulates the pressures accordingly. Another advantage of these modes is that the ventilator may be able to deliver noninvasive “backup breaths,” based on a preset apnea interval when the neonate has stopped breathing. One potential limitation of ventilator CPAP is that the demand flow system may not be able to respond adequately to changes in patient respiratory efforts because pressure is being measured back at the ventilator and not at the patient’s airway. Additionally, new evidence suggests that the expiratory resistance of newer neonatal ventilator’s exhalation valves may impose additional resistance and hence increase the WOB during spontaneous breathing.²⁰

Two commercially available, freestanding CPAP devices that use fluidic gas principles are widely used to provide CPAP to infants. The Hamilton Arabella (Fig. 22-3, A and B) and the CareFusion Infant Flow SiPAP System (Fig. 22-4) are favored by some clinicians. The overall function of these fluidic devices to generate CPAP at the airway is similar. Both devices have a fully integrated flow controller, a delivery circuit, different-sized nasal prongs that attach to a gas delivery manifold, and a bonnet with Velcro straps to secure the manifold and prongs. The manifold incorporates a fluidic flip-flop mechanism at the infant’s nasal airway opening to regulate flow to match the infant’s inspiratory demand and provide a consistent pressure level (see Fig. 22-3, B). The controller provides gas flow with an adjustable F_IO₂ and also monitors CPAP pressure. Turbulence caused by continuous flow has been eliminated in these systems to make exhalation easier and reduce the WOB. The manufacturers have attempted to provide better-fitting, easier-to-secure nasal prongs to make CPAP more effective and patient care easier. These devices are particularly effective at reducing WOB in VLBW infants. CPAP is better tolerated in these patients, which helps to avert the need for positive-pressure ventilation.²¹

Bubble CPAP (B-CPAP) is a technique for delivering CPAP via a simple freestanding system (Fig. 22-5). It has been used in certain forms for more than 30 years and is again gaining favor over other CPAP techniques. In the United States, two B-CPAP devices are now available (B&B Medical, Fischer Paykel), but most centers that implement B-CPAP have done so using homemade systems consisting of a blended and humidified gas source, ventilator circuits, nasal prongs, pressure manometer, and a water column. The blended gas flow is adjusted at 5 L/min, and the CPAP level is regulated by varying the depth of the distal ventilator circuit below the water surface (i.e., 5 cm = 5 cm H₂O CPAP). Higher pressures than those anticipated by the submersion depth of the distal tubing have been observed when using higher flows^22,23; thus clinicians will use the lowest flow possible to maintain constant bubbling throughout the respiratory cycle. An additional safeguard involves measuring the pressure at the nasal airway interface using a pressure manometer and limiting excessive pressures with a safety “pop-off” valve during B-CPAP.

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