Respiratory Support in Neonates and Infants

Oxygen may be given using a nasal cannula or face mask. Oxygen concentration should be set to achieve a PaO2 of 50 to 70 mm Hg in preterm infants Preterm Infants An infant born before 37 weeks of gestation is considered preterm. In 2021 in the United States, 10.48% of births were preterm ( 1), and in 2018, 26.53% of births were early term (significantly... read more and 50 to 80 mm Hg in term infants or an oxygen saturation of 90 to 94% in preterm infants and 92 to 96% in term infants. Lower PaO2 in infants provides almost full saturation of hemoglobin, because fetal hemoglobin has a higher affinity for oxygen; maintaining higher PaO2 increases the risk of retinopathy of prematurity Retinopathy of Prematurity Retinopathy of prematurity is a bilateral disorder of abnormal retinal vascularization in premature infants, especially those of lowest birth weight. Outcomes range from normal vision to blindness... read more and bronchopulmonary dysplasia Bronchopulmonary Dysplasia (BPD) Bronchopulmonary dysplasia is chronic lung disease of the neonate that typically is caused by prolonged ventilation and is further defined by degree of prematurity and extent of supplemental... read more . No matter how oxygen is delivered, it should be warmed (36 to 37° C) and humidified to prevent secretions from cooling and drying and to prevent bronchospasm.

An umbilical artery catheter is usually placed for sampling arterial blood gases in neonates who require fraction of inspired oxygen (FIO2) ≥ 40%. If an umbilical artery catheter cannot be placed, a percutaneous radial artery catheter can be used for continuous blood pressure monitoring and blood sampling if the result of the Allen test Arterial Blood Gas (ABG) Sampling , which is done to assess adequacy of collateral circulation, is normal.

Neonates who are unresponsive to these maneuvers may require fluids to improve cardiac output and are candidates for CPAP ventilation or bag-and-mask ventilation (40 to 60 breaths/minute). CPAP, either ventilator-derived or bubble, can help avoid intubation (and thus minimize ventilator-induced lung injury) even in extremely preterm infants. However, if the infant does not oxygenate with or requires prolonged bag-and-mask ventilation, endotracheal intubation with mechanical ventilation is indicated, although very immature neonates (eg, < 28 weeks gestation or < 1000 g) are sometimes begun on ventilatory support immediately after delivery (see also 1 Oxygen reference Initial stabilization maneuvers include mild tactile stimulation, head positioning, and suctioning of the mouth and nose followed as needed by Supplemental oxygen Continuous positive airway... read more ) so that they can receive preventive surfactant therapy. Because bacterial sepsis Neonatal Sepsis Neonatal sepsis is invasive infection, usually bacterial, occurring during the neonatal period. Signs are multiple, nonspecific, and include diminished spontaneous activity, less vigorous sucking... read more is a common cause of respiratory distress in neonates, it is common practice to draw blood cultures and give antibiotics to neonates with high oxygen requirements pending culture results.

In CPAP, constant pressure is maintained throughout the respiratory cycle, usually 5 to 7 cm H2O, but with no additional inspiratory pressure support. CPAP keeps alveoli open and improves oxygenation by reducing atelectasis and thereby the amount of blood shunted through atelectatic areas while the infant breathes spontaneously. CPAP can be provided using nasal prongs or masks and various apparatuses to provide the positive pressure; it also can be given using an endotracheal tube connected to a conventional ventilator with the rate set to zero.

Bubble CPAP (1 CPAP references Initial stabilization maneuvers include mild tactile stimulation, head positioning, and suctioning of the mouth and nose followed as needed by Supplemental oxygen Continuous positive airway... read more ) is a low-technology way of providing CPAP in which the outflow tubing is simply immersed in water to provide expiratory resistance equal to the depth of the tubing in the water (exhalation makes the water bubble, hence the name).

CPAP is indicated when FIO2 ≥ 40% is required to maintain acceptable PaO2 (50 to 70 mm Hg) in infants with respiratory disorders that are of limited duration (eg, diffuse atelectasis Atelectasis Atelectasis is collapse of lung tissue with loss of volume. Patients may have dyspnea or respiratory failure if atelectasis is extensive. They may also develop pneumonia. Atelectasis is usually... read more , mild respiratory distress syndrome Respiratory Distress Syndrome in Neonates Respiratory distress syndrome is caused by pulmonary surfactant deficiency in the lungs of neonates, most commonly in those born at < 37 weeks gestation. Risk increases with degree of prematurity... read more , lung edema). In these infants, CPAP may preempt the need for positive pressure ventilation.

Common complications of nasal CPAP are gastric distention, aspiration, pneumothorax, and nasal pressure injuries Staging systems Pressure injuries are areas of necrosis and often ulceration (also called pressure ulcers) where soft tissues are compressed between bony prominences and external hard surfaces. They are caused... read more . The need for increasing FIO2 and/or pressure are signs that intubation may be necessary (2 CPAP references Initial stabilization maneuvers include mild tactile stimulation, head positioning, and suctioning of the mouth and nose followed as needed by Supplemental oxygen Continuous positive airway... read more ).

NIPPV (see also Noninvasive positive pressure ventilation [NIPPV] Noninvasive positive pressure ventilation (NIPPV) Mechanical ventilation can be Noninvasive, involving various types of face masks Invasive, involving endotracheal intubation Selection and use of appropriate techniques require an understanding... read more ) delivers positive pressure ventilation using nasal prongs or nasal masks. It can be synchronized (ie, triggered by the infant's inspiratory effort) or nonsynchronized. NIPPV can provide a back-up rate and can augment an infant's spontaneous breaths. Peak pressure can be set to desired limits. It is particularly useful in patients with apnea to facilitate extubation and to help prevent atelectasis. NIPPV has been found to reduce the incidence of extubation failure and the need for reintubation within 1 week more effectively than nasal CPAP; however, it has no effect on the development of chronic lung disease or on mortality.

Endotracheal tubes (ETT) are required for mechanical ventilation (see also Tracheal Intubation Tracheal Intubation Most patients requiring an artificial airway can be managed with tracheal intubation, which can be Orotracheal (tube inserted through the mouth) Nasotracheal (tube inserted through the nose)... read more ).

For ETT diameter:

Intubation is safer if oxygen is insufflated into the infant’s airway during the procedure. Orotracheal intubation is preferred.

For insertion depth, the tube should be inserted such that the

The tip of the endotracheal tube should be positioned about halfway between the clavicles and the carina on chest x-ray, coinciding roughly with vertebral level T2. If position or patency is in doubt, the tube should be removed and the infant should be supported by bag-and-mask ventilation until a new tube is inserted. A CO2 detector is helpful in determining that the tube is placed in the airway (no CO2 is detected with esophageal placement). Acute deterioration of the infant’s condition (sudden changes in oxygenation, arterial blood gases, blood pressure, or perfusion) should trigger suspicion of changes in the position of the tube, patency of the tube, or both.

Modes of ventilation:

In SIMV, the ventilator delivers a set number of breaths of fixed pressure or volume within a time period. These breaths are synchronized with the patient's spontaneous breaths but also will be delivered in the absence of respiratory effort. The patient can take spontaneous breaths in between without triggering the ventilator.

In AC, the ventilator is triggered to deliver a breath of predetermined volume or pressure with each patient inspiration. A back-up rate is set in the event the patient is not taking any or enough breaths.

High-frequency oscillatory ventilation (delivering 400 to 900 breaths/minute at a set mean airway pressure) can be used in infants and is often preferred in extremely preterm infants Preterm, Very Preterm, and Extremely Preterm Infants An infant born before 37 weeks of gestation is considered preterm. In 2021 in the United States, 10.48% of births were preterm ( 1), and in 2018, 26.53% of births were early term (significantly... read more (< 28 weeks gestation) and in some infants with air leaks, widespread atelectasis, or pulmonary edema.

Optimal mode or type of ventilation depends on the infant’s response. Volume ventilators are considered useful for larger infants with varying pulmonary compliance or resistance (eg, in bronchopulmonary dysplasia), because delivering a set volume of gas with each breath ensures adequate ventilation. AC mode is often used for treating less severe pulmonary disease and for decreasing ventilator dependence while providing a small increase in airway pressure or a small volume of gas with each spontaneous breath.

Initial ventilator settings are estimated by judging the severity of respiratory impairment. Typical settings for an infant in moderate respiratory distress are

These settings are adjusted based on the infant’s oxygenation, chest wall movement, breath sounds, and respiratory efforts along with arterial or capillary blood gases.

Patient-triggered ventilation often is used to synchronize the positive pressure ventilator breaths with the onset of the patient’s own spontaneous respirations. This seems to shorten the time on a ventilator and may reduce barotrauma.

Ventilator pressures or volumes should be as low as possible to prevent barotrauma and bronchopulmonary dysplasia; an elevated PaCO2 is acceptable as long as pH remains ≥ 7.25 (permissive hypercapnia). Likewise, a PaO2 as low as 40 mm Hg is acceptable if blood pressure is normal and metabolic acidosis Metabolic Acidosis Metabolic acidosis is primary reduction in bicarbonate (HCO3⁻), typically with compensatory reduction in carbon dioxide partial pressure (Pco2); pH may be markedly low or slightly... read more is not present.

Adjunctive treatments used with mechanical ventilation in some patients include

Paralytics (eg, vecuronium, pancuronium bromide) may facilitate endotracheal intubation and can help stabilize infants whose movements and spontaneous breathing prevent optimal ventilation. These drugs should be used selectively and only in an intensive care unit setting by personnel experienced in intubation and ventilator management because paralyzed infants will not be able to breathe spontaneously if intubation attempts are unsuccessful or the infant is inadvertently extubated; furthermore, paralyzed infants may need greater ventilator support, which can increase barotrauma. Fentanyl can cause chest wall rigidity or laryngospasm, which can lead to difficulty intubating.

Inhaled nitric oxide 5 to 20 ppm may be used for refractory hypoxemia when pulmonary vasoconstriction is a contributor to hypoxia (eg, in idiopathic/ persistent pulmonary hypertension Persistent Pulmonary Hypertension of the Newborn Persistent pulmonary hypertension of the newborn is the persistence of or reversion to pulmonary arteriolar constriction, causing a severe reduction in pulmonary blood flow and right-to-left... read more , pneumonia Neonatal Pneumonia Neonatal pneumonia is lung infection in a neonate. Onset may be within hours of birth and part of a generalized sepsis syndrome or after 7 days and confined to the lungs. Signs may be limited... read more , or congenital diaphragmatic hernia Diaphragmatic Hernia Diaphragmatic hernia is protrusion of abdominal contents into the thorax through a defect in the diaphragm. Lung compression may cause persistent pulmonary hypertension. Diagnosis is by chest... read more ) and may prevent the need for ECMO Extracorporeal Membrane Oxygenation (ECMO) Initial stabilization maneuvers include mild tactile stimulation, head positioning, and suctioning of the mouth and nose followed as needed by Supplemental oxygen Continuous positive airway... read more .

Weaning from the ventilator can occur as respiratory status improves. The infant can be weaned by lowering

As the rate is reduced, the infant takes on more of the work of breathing. Infants who can maintain adequate oxygenation and ventilation on lower settings typically tolerate extubation. The final steps in ventilator weaning involve extubation, possibly support with nasal (or nasopharyngeal) CPAP or NIPPV, and, finally, use of a hood or nasal cannula to provide humidified oxygen or air.

Very low-birth-weight infants may benefit from the addition of a methylxanthine (eg, aminophylline, theophylline, caffeine) during the weaning process. Methylxanthines are central nervous system–mediated respiratory stimulants that increase ventilatory effort and may reduce apneic and bradycardic episodes that may interfere with successful weaning. Caffeine is the preferred agent because it is better tolerated, easier to give, safer, and requires less monitoring.

Corticosteroids, once used routinely for weaning and treatment of chronic lung disease, are no longer recommended in preterm infants because risks (eg, impaired growth, hypertrophic cardiomyopathy) outweigh benefits. A possible exception is as a last resort in near-terminal illness, in which case parents should be fully informed of risks.

ECMO is a form of cardiopulmonary bypass used for infants with respiratory failure who cannot be oxygenated adequately or ventilated with conventional or oscillating ventilators. Eligibility criteria vary by center, but in general, infants should have reversible disease (eg, persistent pulmonary hypertension of the newborn Persistent Pulmonary Hypertension of the Newborn Persistent pulmonary hypertension of the newborn is the persistence of or reversion to pulmonary arteriolar constriction, causing a severe reduction in pulmonary blood flow and right-to-left... read more , congenital diaphragmatic hernia Diaphragmatic Hernia Diaphragmatic hernia is protrusion of abdominal contents into the thorax through a defect in the diaphragm. Lung compression may cause persistent pulmonary hypertension. Diagnosis is by chest... read more , overwhelming pneumonia Neonatal Pneumonia Neonatal pneumonia is lung infection in a neonate. Onset may be within hours of birth and part of a generalized sepsis syndrome or after 7 days and confined to the lungs. Signs may be limited... read more ) and should have been on mechanical ventilation < 7 days. Primary cardiac compromise may also be an indication for ECMO.

After systemic anticoagulation (typically with heparin), blood is circulated through large-diameter catheters from the internal jugular vein into a membrane oxygenator, which serves as an artificial lung to remove CO2 and add oxygen. Oxygenated blood is then circulated back to the internal jugular vein (venovenous ECMO) or to the carotid artery (venoarterial ECMO). Venoarterial ECMO is used when both circulatory support and ventilatory support are needed (eg, in overwhelming sepsis Neonatal Sepsis Neonatal sepsis is invasive infection, usually bacterial, occurring during the neonatal period. Signs are multiple, nonspecific, and include diminished spontaneous activity, less vigorous sucking... read more ). Flow rates can be adjusted to obtain desired oxygen saturation and blood pressure.

ECMO is contraindicated in infants < 34 weeks, < 2 kg, or both because of the risk of intraventricular hemorrhage with systemic heparinization.

Complications of ECMO include thromboembolism, air embolization, neurologic (eg, stroke, seizures) and hematologic (eg, hemolysis, neutropenia, thrombocytopenia) problems, and cholestatic jaundice.