Cyanosis primary prevention
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Prenatal diagnosis
Clinicians skilled at fetal echocardiography are able to identify most congenital heart defects. However, clinical suspicion or a risk factor for CHD must be identified to prompt referral for fetal echocardiography. Routine antenatal ultrasound traditionally included assessment of the fetal heart using the four chamber view; however, the practice guidelines of the International Society for Ultrasound in Obstetrics and Gynecology (ISUOG) published in 2013 now recommend expanded views for screening, including assessment of the outflow tracts [41]. Studies performed in the era prior to publication of these guidelines indicate that less than half of patients with critical congenital heart defects were routinely identified [10,42-44]. CHD lesions involving abnormal outflow tracts (including tetralogy of Fallot (figure 2), double outlet right ventricle [DORV], and transposition of the great arteries [TGA] (figure 3)) are particularly at risk for not being identified. In addition, coarctation of the aorta (COA) (figure 4) is difficult to definitively diagnose prenatally.
The expanded prenatal screening recommendations of the ISUOG may lead to improved detection rates in the future. One study found that the rate of prenatal detection of critical CHD increased from 44 percent in 2007 to 69 percent in 2013 [43].
Prenatal sonographic screening for CHD is discussed in detail separately.
Antenatal corticosteroid therapy — Antenatal corticosteroid (ACS) therapy should be administered to all pregnant women at 23 to 34 weeks who are at increased risk of preterm delivery within the next seven days to prevent or decrease the severity of neonatal RDS. ACS enhances maturational changes in fetal lung architecture and biochemistry with increased synthesis and release of surfactant, resulting in improved neonatal lung function. The efficacy and use of ACS in preterm infants are discussed in greater detail elsewhere. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery".)
Assisted ventilation techniques — Respiratory support that prevents and reduces atelectasis should be administered to all preterm infants who are at risk for RDS. In our center, nasal continuous positive airway pressure (nCPAP) is the preferred modality to provide positive end-expiratory pressure (PEEP). Limited data suggest that nasal intermittent positive pressure ventilation (NIPPV) may be a reasonable alternative to nCPAP.
These less invasive modalities (nCPAP and NIPPV) have replaced intubation and mechanical ventilation as the initial intervention that provides positive pressure to reduce the risk of atelectasis. However, for some patients who do not adequately respond to nCPAP or NIPPV, intubation and mechanical ventilation with PEEP may be needed (algorithm 1).
Nasal continuous positive airway pressure — In preterm infants at-risk for or with established RDS without respiratory failure, nCPAP is the initial preferred intervention versus the combined regimen of endotracheal intubation, surfactant therapy, and mechanical ventilation [1,3-7]. This approach is consistent with our own practice (algorithm 1) and the recommendations from the American Academy of Pediatrics (AAP), American Heart Association (AHA), International Liaison Committee on Resuscitation (ILOR) guidelines, and the European Consensus Guidelines [1,2,8,9]. (See 'Management approach' below.)
Several systematic reviews have shown that CPAP is more effective with lower mortality and reduced risk of bronchopulmonary dysplasia (BPD) compared with intubation with or without surfactant administration [10-12]. nCPAP was also associated with a reduction in mortality and the combined outcome of death or mechanical ventilation compared with supportive care with supplemental oxygen without positive pressure support [7].
Follow-up studies at 18 to 22 months corrected age of one of the clinical trials (Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial [SUPPORT study]) included in the above mentioned systematic reviews showed less respiratory morbidity for the group that was assigned to nCPAP and no difference in death or neurodevelopmental outcome between the nCPAP and intubation/surfactant groups [13-15].
In our center, nCPAP is also used when patients are extubated, as it reduces the incidence of adverse clinical events (apnea, respiratory acidosis, and increased oxygen requirements) and the need for reintubation [16].
Caffeine — The use of early administration of caffeine therapy has been proposed to enhance the use of CPAP as caffeine is used to increase respiratory drive for infants less than 28 weeks gestation as apnea is a universal finding. Although data are inconsistent, we administer prophylactic caffeine therapy in extremely low birth weight (ELBW) infants (BW <1000 g) as these patients universally will have apnea of prematurity and are at greatest risk for developing BPD. (See "Management of apnea of prematurity", section on 'Prophylactic use' and "Prevention of bronchopulmonary dysplasia", section on 'Caffeine'.)
Support for early caffeine administration was provided by a multicenter trial of preterm infants (BW between 500 and 1250 g) that founded a lower incidence of BPD for infants who were assigned to caffeine compared with those who received placebo [17]. However, a subsequent large multicenter observational study reported that early caffeine treatment (within the first week of life) did not reduce the risk of CPAP failure for very low compared with routine use of caffeine for apnea of prematurity for VLBW infants (22 versus 21 percent) [18]. Subgroup analysis based on birth weights and gestational age categories also did not show a beneficial effect from caffeine.
Failure of CPAP — Patients with neonatal RDS who fail continuous positive airway pressure (CPAP) (defined as pH below 7.25 or who require oxygen supplementation of an FiO2 ≥0.40) require intubation and administration of surfactant. CPAP failure increases with decreasing gestational age and is associated with increased mortality and morbidity. This was illustrated in a large cohort of preterm infants that reported failure rates of CPAP of 43 percent for infants born between 25 and 28 weeks gestation, and 21 percent for those born between 28 and 32 weeks gestation [19]. After adjusting for confounding factors, the incidence of death or BPD was increased for infants regardless of gestational age who failed CPAP compared with those in whom CPAP was successful.
Long-term outcome — However, the use of CPAP is still associated with long-term morbidity. This was illustrated in an observational Australian study that correlated pulmonary function for extremely preterm survivors (gestational age <28 weeks) at eight years of age with neonatal respiratory care over three time periods (1991 to 1992, 1997, and 2005) [20]. Although the use of nasal CPAP increased over the three time periods, there was no improvement in pulmonary function at eight years of age (eg, risk of airflow obstruction). In fact, contrary to expected results, the 2005 cohort with the longest duration of CPAP use had the highest degree of airflow obstruction at eight years of age and greatest risk of BPD. However, interpretation of these results must take in to consideration other temporal factors including the marked decrease in the use of postnatal steroids (which reduces the risk of BPD) in 2005 compared with the other time periods and the higher mortality rate in the earliest time period of 1991 to 1992, which may have reduced the number of survivors at risk for BPD. Other limitations in comparing results across the three time periods included the potential increased duration of CPAP usage in 2005 for other conditions including apnea of prematurity and recurrent episodes of deoxyhemoglobin.
These findings are consistent with those reported in a neonatal rodent model that demonstrated adverse long-term effects of CPAP and oxygen exposure used to treat recurrent intermittent hypoxia and hyperoxia on airway reactivity [21].
These data emphasis that clinicians need to follow the criteria used for initiation and discontinuation of CPAP to avoid its overuse and minimize long-term sequelae (algorithm 1) (see 'Initial neonatal management in the delivery room' below and "Neonatal target oxygen levels for preterm infants"). Nevertheless, as shown above, CPAP remains the preferred intervention for the management of neonatal RDS to the regimen of endotracheal intubation and surfactant administration.
Nasal intermittent positive pressure ventilation — NIPPV is a delivery mode of positive pressure ventilation that avoids the trauma of endotracheal placement tube. It augments nCPAP by delivering ventilator breaths via nasal prongs (or nasal mask). As a result, it requires the use of a ventilator, whereas nCPAP is administered through a less costly bubble CPAP device. Limited evidence of moderate quality suggest that the early use of NIPPV is superior to nCPAP as an initial treatment for noninvasive respiratory support for preterm infants with RDS. However, until further data conclusively confirm that NIPPV is more effective and remains comparable in cost and safety, we continue to use nCPAP. (See "Noninvasive oxygen delivery and oxygen monitoring in the newborn", section on 'Nasal intermittent positive pressure ventilation'.)
In a systematic review, early initiation of NIPPV compared with CPAP reduced the risk of respiratory failure (relative risk [RR] 0.65, 95% CI 0.51-0.82) and intubation (RR 0.78, 95% CI 0.64-0.94) for preterm infants with RDS [22]. There was no difference between the two interventions in reducing the risk of BPD (RR 0.78, 95% CI 0.58 to 1.06). The evidence of the included studies was assessed as moderate due to lack of blinding, which may result in potential bias. The study population for many of these trials included older infants between 34 to 37 weeks gestation who do not have as high a risk of RSD and BPD than more preterm infants (gestational age <32 weeks). Additional larger trials are needed to confirm these results especially in very preterm infants (gestational age <32 weeks) and to assess the safety of NIPPV compared with nCPAP.
High-flow nasal cannulae — Heated, humidified high-flow nasal cannulas (HFNC) are increasingly being used to provide positive distending pressure with or without oxygen instead of traditional nCPAP devices. However, a clinical trial reported a higher failure rate when HFNC was used as the primary therapy for neonatal RDS compared with nCPAP [23]. In addition, pressure delivery is highly variable. As a result, we do not use HFNC as an initial measure to prevent or treat neonatal RDS. (See "Noninvasive oxygen delivery and oxygen monitoring in the newborn", section on 'High flow'.)
Endotracheal intubation and mechanical ventilation
Indications — Endotracheal intubation and mechanical ventilation are indicated for patients who fail to respond to less invasive forms of ventilation. In our practice, intubation and ventilation are initiated when one or more of the following criteria are verified (algorithm 1):
●Respiratory acidosis, documented by an arterial pH <7.2 and partial pressure of arterial carbon dioxide (PaCO2) >60 to 65 mmHg.
●Hypoxemia documented by an arterial partial pressure of oxygen (PaO2) <50 mmHg despite oxygen supplementation, or when the fraction of inspired concentration (FiO2) exceeds 0.40 on nCPAP.
●Severe apnea.
Choice of ventilatory mode — Mechanical ventilation due to volutrauma, barotrauma, and oxygen toxicity is a risk factor for BPD for preterm infants with RDS. Although there are several different mechanical ventilation modalities, including pressure control ventilation, volume control, and high-frequency positive pressure ventilation, the optimal mode of ventilation to reduce mortality and BPD remains unclear in patients with RDS who require mechanical ventilation. Based on the available literature, the initial ventilatory mode for preterm infants with RDS used in our center is synchronized volume-targeted ventilation. Target tidal volumes for volume guarantee are set at 4 to 6 mL/kg with permissive hypercarbia (PaCO2 50 to 55 mmHg with pH ≥7.2). Endotracheal tube leaks are minimized by optimizing tube position and size. We do not routinely use high-frequency ventilators in treating neonates who require respiratory support, because this mode of ventilation does not add any significant benefit over the less costly and easier to operate conventional ventilators. (See "Pathogenesis and clinical features of bronchopulmonary dysplasia", section on 'Mechanical ventilation' and "Mechanical ventilation in neonates".)
Regardless of the choice of ventilator, the goal is to use settings that minimize volutrauma, barotrauma, and oxygen toxicity, thereby reducing the risk of BPD, but still reach the target oxygen saturation and PaCO2 levels, discussed in the next section.
Target oxygen saturation — The goal of target oxygen saturation is to set a range so that both hypoxia and the excess use of oxygen can be avoided. In our center, we target oxygen saturation levels based upon pulse oximetry (SpO2) between 90 and 95 percent.
Data comparing high and low target oxygen saturation levels demonstrate that values above 95 percent and below 89 percent are associated with poorer outcome in very preterm infants. This evidence is discussed in detail separately. (See "Neonatal target oxygen levels for preterm infants", section on 'Oxygen target levels'.)
Target carbon dioxide levels — In our practice, the target PaCO2 levels for ventilated preterm infants are between 45 and 60 mmHg.
●When PaCO2 exceeds 60 mmHg, pH usually falls below 7.25, which may compromise cardiovascular function in the initial stages of RDS. In infants managed via an nCPAP-based strategy, PaCO2 exceeding 60 mmHg and pH <7.2 are indications of respiratory failure requiring intubation and mechanical ventilation. Sudden unexplained hypercapnia (in the absence of apnea) may be a sign of airway obstruction, air leak, or patent ductus arteriosus, and should be managed accordingly.
●Hypocapnia (PaCO2 <40 mmHg) is most likely to occur in intubated, ventilated patients and is an indication for decreasing ventilator support. Apart from the risk of excessive ventilator support causing lung damage, hypocapnia also decreases cerebral blood flow.
However, the optimal target for PaCO2 is not established as illustrated by the following:
●Supportive data for our approach are provided by secondary analysis of data from the SUPPORT study showing that higher PaCO2 levels were associated with increased risk of mortality, severe intraventricular hemorrhage, BPD, or neurodevelopmental impairment [24].
●In contrast, another multicenter trial of extremely low birth weight (ELBW) preterm infants (BW <1000 g) reported no difference between preterm infants assigned to a high target PaCO2 (target ranging from 60 to 75 mmHg) compared with the standard control group (45 to 60 mmHg) in the combined primary outcome of death or BPD, and the secondary outcomes of mortality (14 versus 11 percent), or the risk of grade 3 and 4 intraventricular hemorrhage (15 versus 12 percent) or severe retinopathy of prematurity (11 versus 14 percent [25]. In a follow-up report, there was no difference in neurodevelopmental outcome between the two groups [26].
Further trials are needed to elucidate the optimal target range of PaCO2. In addition, the optimal target levels may change for infants who develop BPD. (See "Management of bronchopulmonary dysplasia", section on 'Mechanical ventilation'.)
Based on the available limited data, we take a conservative approach, avoiding both high (PaCO2 >60 mmHg) and low (PaCO2 <45 mmHg) levels of carbon dioxide.
Blood gas monitoring — An arterial sample is optimal for blood gas monitoring as venous or capillary samples are not useful for estimating PaO2. Venous and capillary samples can be used to monitor PaCO2 as they only slightly overestimate PaCO2 and underestimate pH. In the presence of respiratory failure, or need for supplemental oxygen >40 percent, an indwelling arterial line (eg, umbilical arterial catheter) is optimal for blood gas monitoring every four to six hours or more often, if needed. (See "Noninvasive oxygen delivery and oxygen monitoring in the newborn", section on 'Measurement of oxygenation' and "Arterial blood gases".)
Surfactant therapy — Exogenous surfactant replacement therapy is effective in reducing RDS mortality and morbidity in preterm infants [27-30]. Several clinical trials have shown the benefit of surfactant administration in preterm infants born less than 30 weeks gestation who are at the greatest risk for RDS [27,29,31,32]. In these trials, surfactant therapy compared with placebo was associated with a lower incidence and severity of RDS and mortality, and a decreased rate of associated complications including BPD, pulmonary interstitial emphysema, and other pulmonary leak complications, such as pneumothorax [27,29,31,32].
When surfactant therapy is used, the following issues must be addressed:
●Selection of surfactant preparation
●Indications for surfactant therapy
●Timing of administration
●Technical aspects of administration
Types of surfactant — Surfactant preparations include natural and synthetic surfactants. Although both types of surfactant preparations are effective, natural surfactants have been shown to be superior in clinical trials to synthetic preparations that did not contain protein B and C analogues [3,33,34]. In particular, the use of natural preparations was associated with lower inspired oxygen concentration and ventilator pressures, decreased mortality, and lower rate of RDS complications in preterm infants.
Three natural surfactants derived from either bovine or porcine lungs are commercially available in the United States (table 1). It appears that there are no clinically significant differences amongst the three preparations [35,36]:
●Poractant alfa – Porcine lung minced extract
●Calfactant – Bovine lung lavage extract
●Beractant – Bovine lung minced extract
Natural surfactants are obtained by either animal lung lavage or by mincing animal lung tissue, and subsequently purified by lipid extraction that removes hydrophilic components, including hydrophilic surfactant proteins A and D. The purified lipid preparation retains surfactant proteins B and C, neutral lipids, and surface active phospholipids (PL) such as dipalmitoylphosphatidylcholine (DPPC). DPPC is the primary surface-active component that lowers alveolar surface tension.
Although, the US Food and Drug Administration (FDA) approved the first synthetic peptide-containing surfactant (lucinactant) [37,38], it is no longer commercially available as the manufacturer has voluntarily discontinued production.
Indications — Our approach, which is consistent with the 2014 American Academy of Pediatrics (AAP) and the European Consensus Guidelines (ECG) recommendations, is to initially provide nCPAP to all patients with RDS, and intubate and administer surfactant to those with persistent severe respiratory distress (defined as requiring a fraction of inspired oxygen [FiO2] of 0.40 or higher to maintain oxygen saturation above 90 percent) or who are apneic (algorithm 1) [1-3].
Response to initial dose — Additional doses of surfactant therapy are administered if the patient has a persistent requirement of an FiO2 >0.30. Subsequent surfactant administration may decrease mortality and morbidity in infants less than 30 weeks gestation with RDS [27,39]. (See 'Management approach' below and "Mechanical ventilation in neonates", section on 'Indications for ventilation'.)
If the infant maintains adequate respiratory efforts and has an FiO2 requirement less than 0.30, no additional doses of surfactant are needed and the patient can be extubated to nCPAP [27,39].
Timing — If surfactant therapy is used, it is most effective when given within the first 30 to 60 minutes of life following placement of a pulse oximeter and clinical confirmation of correct endotracheal tube placement. However, the potential benefits of timely administration of surfactant must be balanced with adequate time for an initial trial of nCPAP [27,40,41].
Surfactant administration technique
Endotracheal administration — Endotracheal intubation has been the standard technique of surfactant administration. However, surfactant administration may be complicated by transient airway obstruction [3,42] or inadvertent instillation into only the right main stem bronchus if the endotracheal tube is advanced too far in the airway. During administration, oxygen saturation needs to be monitored, as oxygen desaturation may occur. Other complications associated with intubation and mechanical ventilation include pulmonary injury due to volutrauma and barotrauma associated with intermittent positive pressure ventilation, pulmonary air leak, and airway injury due to intubation. (See 'Endotracheal tube complications' below.)
Less invasive measures — Due to the complications from the delivery of surfactant by intubation, minimal or less invasive administrative techniques have been developed and appear promising. These interventions include aerosolized surfactant preparations, laryngeal mask airway-aided delivery of surfactant, pharyngeal instillation, and the use of thin intratracheal catheters [43-49].
However, evidence is of moderate quality that support their use over the traditional endotracheal administration. As a result, we continue to administer surfactant through the endotracheal route until there are conclusive data of the effectiveness, safety, and generalizability of these new noninvasive techniques. The use of less invasive measures to administer surfactant has expanded, especially in European centers [50]. However, there is wide variation in the administration and techniques used and in patient selection.
A systematic review of six clinical trials found that the less invasive thin intratracheal catheter compared with the standard endotracheal intubation administration was associated with a lower rate of the composite outcome of death and BPD at 36 weeks (RR 0.75, 95% CI 0.59-0.94), risk of BPD among survivors (RR 0.72, 95% CI 0.53-0.97), mechanical ventilation within 72 hours of birth (RR 0.71 95% CI 0.53-0.96), or mechanical ventilation during the hospital stay (RR 0.66, 95% CI 0.47 to 0.93) [51]. There were no difference in mortality, need for additional surfactant doses, or procedure failure rates between the two groups. However, these data are limited by concerns for potential bias as none of the included studies were blinded, three studies did not describe the method of randomization, and two did not describe allocation concealment.
Similar results for BPD, mortality, and the combined outcome of BPD and mortality were noted in a second systematic review that included the same trials [52]. In addition, the less invasive instillation administration was associated with a lower risk of CPAP failure or invasive ventilation (RR 0.67, 95% CI 0.53-0.88).
A systematic review that utilized network meta-analyses and ranking probability also found that less invasive surfactant administration was the best strategy for respiratory support for preterm infants with or at risk for RDS for both the primary outcome of death or BPD and four secondary outcomes of BPD, death, grade 3 or 4 intraventricular hemorrhage, and pulmonary air leak [53].
Although these results are encouraging, the quality of evidence is low based on serious risk of bias (unblinded care provider, small sample sizes, and heterogeneity amongst studies) [53,54]. Nevertheless, these data demonstrate that surfactant can be administered in a less invasive manner compared with endotracheal administration. Further studies are needed to show that this less invasive method can be used universally including standardization of delivery and the ability to adequately train healthcare personnel.
Surfactant in combination with budesonide — Limited data in preterm infants with severe RDS requiring mechanical ventilation suggest that the combination of surfactant and budesonide(corticosteroid) reduced the incidence of BPD and the composite outcome of death and BPD [55]. There was no difference in mortality. However, there were several limitations raising concern of bias, including small number of patients, studies performed by the same group, incomplete blindness in the study design, and follow-up of the entire cohort at two to three years of age. As a result, the combination of surfactant and budesonide cannot be recommended until there are larger studies that show definite benefit that outweighs any adverse effect of the intervention.
Inhaled nitric oxide — Data from clinical trials show that the use of inhaled nitric oxide (iNO) either as rescue or routine therapy is not beneficial in preterm infants with RDS in reducing mortality or the risk of BPD. As a result, we concur with the 2014 AAP clinical report and the ECG guidelines that iNO should not be used to treat preterm infants with RDS except in rare cases of pulmonary hypertension or hypoplasia [2,56]. The evidence is discussed in greater detail separately. (See "Prevention of bronchopulmonary dysplasia", section on 'Nitric oxide'.)
SUPPORTIVE CARE — General supportive care for preterm infants with RDS is focused on optimizing the infant's metabolic and cardiorespiratory status. These measures decrease complication rates by reducing oxygen consumption and caloric needs, and concomitant risk factors for poor outcome such as fluid overload and systemic hypotension. In addition, adequate nutrition is vital in the care of these infants to provide energy for metabolic needs and growth.
General supportive care includes:
●Provision of a thermal neutral environment
●Fluid management focused on avoiding overhydration and the use of diuretics
●Maintenance of a stable cardiovascular state
Thermoregulation — Infants should be maintained in a thermal neutral environment to minimize heat loss and maintain the core body temperature in a normal range, thereby reducing oxygen consumption and caloric needs. The ambient temperature should be selected to maintain an anterior abdominal skin temperature in the 36.5 to 37ºC range. Rectal temperatures should be avoided in infants with RDS because of the greater risk of trauma or perforation associated with their use. As a result, abdominal temperatures are used to set the servo-controlling temperatures in incubators and in radiant warmers. (See "Short-term complications of the preterm infant", section on 'Hypothermia'.)
Fluid management — Fluids should be adjusted to maintain a slightly negative water balance, as infants are born in a positive fluid state. Excessive fluid intake may increase the risk of patent ductus arteriosus (PDA), necrotizing enterocolitis (NEC), and bronchopulmonary dysplasia (BPD) [57] and should be avoided. (See "Fluid and electrolyte therapy in newborns".)
There is no evidence to support the routine use of diuretics (particularly furosemide) in preterm infants with RDS [58]. Diuretic use should be avoided because it often results in serum electrolyte abnormalities, and in the case of loop diuretics, nephrocalcinosis, especially hyponatremia and hypokalemia, due to urinary loss of sodium and potassium. (See "Fluid and electrolyte therapy in newborns", section on 'Disorders of sodium balance'.)
Cardiovascular management — Cardiovascular management is focused on ensuring adequate perfusion for all patients. Systemic hypotension occurs commonly in the early stages of RDS. As a result, blood pressure should be frequently monitored noninvasively or continuously via intravascular catheter. However, intervention is not usually required for extremely low birth weight (ELBW) infants (BW <1000 g) with adequate perfusion. In contrast, infants with poor perfusion are in shock and require resuscitation to stabilize their hemodynamic state. (See "Etiology, clinical manifestations, evaluation, and management of low blood pressure in extremely preterm infants", section on 'Management approach' and "Etiology, clinical manifestations, evaluation, and management of neonatal shock".)
PDA is common in preterm infants with RDS. It may manifest as hypercapnia and contribute to difficulties in weaning from mechanical ventilation, which may predispose the patient to BPD. The clinical features, diagnosis, and management of PDA in preterm infants are discussed separately. (See "Pathophysiology, clinical manifestations, and diagnosis of patent ductus arteriosus in premature infants" and "Management of patent ductus arteriosus in preterm infants".)
Nutrition — The administration of early nutrition is important in the overall care of preterm infants. Energy needs must cover both metabolic expenditure (eg, resting metabolic rate and thermoregulation), and growth. The nutritional needs of preterm infants, especially very low birth weight (VLBW) infants (BW <1500 g), are often dependent upon parenteral nutrition (PN) during early postnatal life. (See "Parenteral nutrition in premature infants" and "Approach to enteral nutrition in the premature infant".)
MANAGEMENT APPROACH — Although our approach using specific interventions is based on the available literature as discussed above, there remain significant gaps in our knowledge on how best to prevent and treat neonatal RDS. As a result, there is variability in the management of RDS in preterm infants among institutions.
Antenatal care — In our center, a course of antenatal corticosteroids is given to pregnant women in preterm labor up to 34 weeks gestation to prevent or reduce the severity of neonatal RDS. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery", section on '22+0 to 33+6 weeks'.)