Neonatal and Obstetric Provider Perceptions and Management at 22 Weeks' Gestation

OBJECTIVE

 Active treatment for periviable infants may be influenced by neonatal and obstetric provider perceptions of prognosis. The two aims of this study are to (1) quantify prognostic discordance between provider and data-driven survival estimates and (2) evaluate if prognostic discordance is associated with the threshold probability of survival at which neonatal providers recommend active treatment or obstetric providers recommend antenatal corticosteroids.

STUDY DESIGN

 Provider survival estimates and threshold probabilities of survival for active treatment and antenatal steroid use were obtained from a case-based survey for an infant or pregnancy at 22 weeks' gestation that was administered at two Atlanta hospitals. Data-driven survival estimates, including ranges, were acquired through the National Institute of Child Health and Human Development Extremely Preterm Birth Outcomes Tool. Prognostic discordance was calculated as the difference between a provider and data-driven estimates and classified as pessimistic (provider estimate below data-driven estimate range), accurate (within range), or optimistic (above range). The association between prognostic discordance and the threshold probability of survival was evaluated using nonparametric tests.

RESULTS

 We had 137 neonatal respondents (51% response rate) and 57 obstetric responses (23% response rate). The overall median prognostic discordance was 1.5% (interquartile range: 17, 13) and 52 (27%) of all respondents were pessimistic, 100 (52%) were accurate, and 42 (22%) were optimistic. The survival threshold above which neonatal and obstetric providers recommended active treatment or antenatal corticosteroids was 30% (20-45%) and 10% (0-20%), respectively. Thresholds did not significantly differ among the three prognostic discordance groups (p = 0.45 for neonatal and p = 0.53 for obstetric providers). There was also no significant correlation between the magnitude of prognostic discordance and thresholds.

CONCLUSION

 Prognostic discordance exists among both neonatal and obstetric providers. However, this discordance is not associated with the threshold probability of survival at which providers recommend active treatment or antenatal corticosteroids at 22 weeks' gestation.

KEY POINTS

· Prognostic discordance at 22 weeks' gestation exists for neonatal and obstetric providers.. · Prognostic discordance is not associated with survival thresholds for neonatal active treatment.. · Prognostic discordance is not associated with survival thresholds for the use of antenatal corticosteroids..

Chronic lung disease in full-term infants: Characteristics and neonatal intensive care outcomes in infants referred to children's hospitals

OBJECTIVE

To describe characteristics, outcomes, and risk factors for death or tracheostomy with home mechanical ventilation in full-term infants with chronic lung disease (CLD) admitted to regional neonatal intensive care units.

STUDY DESIGN

This was a multicenter, retrospective cohort study of infants born ≥37 weeks of gestation in the Children's Hospitals Neonatal Consortium.

RESULTS

Out of 67,367 full-term infants admitted in 2010-2016, 4886 (7%) had CLD based on receiving respiratory support at either 28 days of life or discharge. 3286 (67%) were still hospitalized at 28 days receiving respiratory support, with higher mortality risk than those without CLD (10% vs. 2%, p < 0.001). A higher proportion received tracheostomy (13% vs. 0.3% vs. 0.4%, p < 0.001) and gastrostomy (30% vs. 1.7% vs. 3.7%, p < 0.001) compared to infants with CLD discharged home before 28 days and infants without CLD, respectively. The diagnoses and surgical procedures differed significantly between the two CLD subgroups. Small for gestational age, congenital pulmonary, airway, and cardiac anomalies and bloodstream infections were more common among infants with CLD who died or required tracheostomy with home ventilation (p < 0.001). Invasive ventilation at 28 days was independently associated with death or tracheostomy and home mechanical ventilation (odds ratio 7.6, 95% confidence interval 5.9-9.6, p < 0.0001).

CONCLUSION

Full-term infants with CLD are at increased risk for morbidity and mortality. We propose a severity-based classification for CLD in full-term infants. Future work to validate this classification and its association with early childhood outcomes is necessary.

A comparison of newer classifications of bronchopulmonary dysplasia: findings from the Children's Hospitals Neonatal Consortium Severe BPD Group

OBJECTIVE

To compare three bronchopulmonary dysplasia (BPD) definitions against hospital outcomes in a referral-based population.

STUDY DESIGN

Data from the Children's Hospitals Neonatal Consortium were classified by 2018 NICHD, 2019 NRN, and Canadian Neonatal Network (CNN) BPD definitions. Multivariable models evaluated the associations between BPD severity and death, tracheostomy, or length of stay, relative to No BPD references.

RESULTS

Mortality was highest in 2019 NRN Grade 3 infants (aOR 225), followed by 2018 NICHD Grade 3 (aOR 145). Infants with lower BPD grades rarely died (<1%), but Grade 2 infants had aOR 7-21-fold higher for death and 23-56-fold higher for tracheostomy.

CONCLUSIONS

Definitions with 3 BPD grades had better discrimination and Grade 3 2019 NRN had the strongest association with outcomes. No/Grade 1 infants rarely had severe outcomes, but Grade 2 infants were at risk. These data may be useful for counseling families and determining therapies for infants with BPD.

Association of time of first corticosteroid treatment with bronchopulmonary dysplasia in preterm infants

OBJECTIVE

To evaluate the association between the time of first systemic corticosteroid initiation and bronchopulmonary dysplasia (BPD) in preterm infants.

STUDY DESIGN

A multi-center retrospective cohort study from January 2010 to December 2016 using the Children's Hospitals Neonatal Database and Pediatric Health Information System database was conducted. The study population included preterm infants <32 weeks' gestation treated with systemic corticosteroids after 7 days of age and before 34 weeks' postmenstrual age. Stepwise multivariable logistic regression was used to assess the association between timing of corticosteroid initiation and the development of Grade 2 or 3 BPD as defined by the 2019 Neonatal Research Network criteria.

RESULTS

We identified 598 corticosteroid-treated infants (median gestational age 25 weeks, median birth weight 760 g). Of these, 47% (280 of 598) were first treated at 8-21 days, 25% (148 of 598) were first treated at 22-35 days, 14% (86 of 598) were first treated at 36-49 days, and 14% (84 of 598) were first treated at >50 days. Infants first treated at 36-49 days (aOR 2.0, 95% CI 1.1-3.7) and >50 days (aOR 1.9, 95% CI 1.04-3.3) had higher independent odds of developing Grade 2 or 3 BPD when compared to infants treated at 8-21 days after adjusting for birth characteristics, admission characteristics, center, and co-morbidities.

CONCLUSIONS

Among preterm infants treated with systemic corticosteroids in routine clinical practice, later initiation of treatment was associated with a higher likelihood to develop Grade 2 or 3 BPD when compared to earlier treatment.

Qualitative indications for tracheostomy and chronic mechanical ventilation in patients with severe bronchopulmonary dysplasia

BACKGROUND

The decision to pursue chronic mechanical ventilation involves a complex mix of clinical and social considerations. Understanding the medical indications to pursue tracheostomy would reduce the ambiguity for both providers and families and facilitate focus on appropriate clinical goals.

OBJECTIVE

To describe potential indications to pursue tracheostomy and chronic mechanical ventilation in infants with severe BPD (sBPD).

STUDY DESIGN

We surveyed centers participating in the Children's Hospitals Neonatal Consortium to describe their approach to proceed with tracheostomy in infants with sBPD. We requested a single representative response per institution. Question types were fixed form and free text responses.

RESULTS

The response rate was high (31/34, 91%). Tracheostomy was strongly considered when: airway malacia was present, PCO₂ ≥ 76-85 mmHg, FiO₂ ≥ 0.60, PEEP ≥ 9-11 cm H₂O, respiratory rate ≥ 61-70 breaths/min, PMA ≥ 44 weeks, and weight <10th %ile at 44 weeks PMA.

CONCLUSIONS

Understanding the range of indications utilized by high level NICUs around the country to pursue a tracheostomy in an infant with sBPD is one step toward standardizing consensus indications for tracheostomy in the future.

Utility of echocardiography in predicting mortality in infants with severe bronchopulmonary dysplasia

OBJECTIVE

To determine the relationship between interventricular septal position (SP) and right ventricular systolic pressure (RVSP) and mortality in infants with severe BPD (sBPD).

STUDY DESIGN

Infants with sBPD in the Children's Hospitals Neonatal Database who had echocardiograms 34-44 weeks' postmenstrual age (PMA) were included. SP and RVSP were categorized normal, abnormal (flattened/bowed SP or RVSP > 40 mmHg) or missing.

RESULTS

Of 1157 infants, 115 infants (10%) died. Abnormal SP or RVSP increased mortality (SP 19% vs. 8% normal/missing, RVSP 20% vs. 9% normal/missing, both p < 0.01) in unadjusted and multivariable models, adjusted for significant covariates (SP OR 1.9, 95% CI 1.2-3.0; RVSP OR 2.2, 95% CI 1.1-4.7). Abnormal parameters had high specificity (SP 82%; RVSP 94%), and negative predictive value (SP 94%, NPV 91%) for mortality.

CONCLUSIONS

Abnormal SP or RVSP is independently associated with mortality in sBPD infants. Negative predictive values distinguish infants most likely to survive.

Atrial Septal Defects Accelerate Pulmonary Hypertension Diagnoses in Premature Infants

Between 4 and 16% of extremely premature infants have late pulmonary hypertension (PH) (onset >30 days of life), and infants with PH have a higher risk of tracheostomy and death. Atrial septal defects (ASD) increase pulmonary blood flow and may promote PH in at-risk infants. The objective of this study was to determine if infants with ASD develop PH sooner than those without ASD. Infants who were born at < 32 weeks' gestation, with an echocardiogram on day of life > 30, and without congenital anomalies were included. Infants with and without ASD were evaluated for the time to PH diagnosis, defined as the day of the first echocardiogram that showed PH. A multivariable model with ASD and significant variables on PH and a Cox proportional hazard model evaluating time to PH was determined. Of the 334 infants with echocardiograms, 57 had an ASD and 26% of these developed PH vs. 12% without ASD (p = 0.006). Infants with PH had lower gestational age (25.2 vs. 26.2 weeks, p = 0.005), smaller birthweight (699 vs. 816 gm, p = 0.001), and more prematurity complications than infants without PH. More PH infants had maternal African-American race (63.9 vs. 36.1%), right ventricular dysfunction (23.9 vs. 3.2%, p < 0.001), right ventricular dilation (52.1 vs. 8.6%, p < 0.001), or right ventricular hypertrophy (51.2 vs. 10.1%, p < 0.001), than infants without PH. At 150 days of life, 78.1% (95% CI 64.6-86.9%) of infants with ASD survived without PH, compared with 90.9% (95% CI 86.7-93.8%) of infants without ASD, and the unadjusted hazard for development of PH for infants with ASD was 2.37 (95% CI 1.29-4.36). When significant clinical variables were controlled, infants with ASD had a 2.44-fold (95% CI 1.27-4.68) increase in PH, compared with infants without ASD. Most PH in infants with or without ASD was diagnosed by day of life 150, but infants with ASD had an over 2-fold increased hazard for PH during their neonatal hospitalization. Premature infants with ASD should be followed closely for PH development and further studies to investigate the optimal timing of closure are needed.

Hyperoxia induces paracellular leak and alters claudin expression by neonatal alveolar epithelial cells

BACKGROUND

Premature neonates frequently require oxygen supplementation as a therapeutic intervention that, while necessary, also exposes the lung to significant oxidant stress. We hypothesized that hyperoxia has a deleterious effect on alveolar epithelial barrier function rendering the neonatal lung susceptible to injury and/or bronchopulmonary dysplasia (BPD).

MATERIALS AND METHODS

We examined the effects of exposure to 85% oxygen on neonatal rat alveolar barrier function in vitro and in vivo. Whole lung was measured using wet-to-dry weight ratios and bronchoalveolar lavage protein content and cultured primary neonatal alveolar epithelial cells (AECs) were measured using transepithelial electrical resistance (TEER) and paracellular flux measurements. Expression of claudin-family tight junction proteins, E-cadherin and the Snail transcription factor SNAI1 were measured by Q-PCR, immunoblot and confocal immunofluorescence microscopy.

RESULTS

Cultured neonatal AECs exposed to 85% oxygen showed impaired barrier function. This oxygen-induced increase in paracellular leak was associated with altered claudin expression, where claudin-3 and -18 were downregulated at both the mRNA and protein level. Claudin-4 and -5 mRNA were also decreased, although protein expression of these claudins was largely maintained. Lung alveolarization and barrier function in vivo were impaired in response to hyperoxia. Oxygen exposure also significantly decreased E-cadherin expression and induced expression of the SNAI1 transcription factor in vivo and in vitro.

CONCLUSIONS

These data support a model in which hyperoxia has a direct impact on alveolar tight and adherens junctions to impair barrier function. Strategies to antagonize the effects of high oxygen on alveolar junctions may potentially reverse this deleterious effect.

Early characteristics of infants with pulmonary hypertension in a referral neonatal intensive care unit

Background

Approximately 8–23% of premature infants develop pulmonary hypertension (PH), and this diagnosis confers a higher possibility of mortality. As a result, professional societies recommend PH screening in premature infants. However, the risk factors for and the outcomes of PH may differ depending on the timing of its diagnosis, and little evidence is available to determine at-risk infants in the referral neonatal population. The objective of this study was to define clinical and echocardiographic characteristics of infants with pulmonary hypertension during the neonatal hospital course and at or near-term.

Methods

Infants who had the following billing codes: < 32 weeks, birth weight < 1500 g, neonatal unit, and echocardiograph had records abstracted from a data warehouse at Children’s Healthcare of Atlanta. The outcome was defined as late PH on the final echocardiogram for all patients, and, separately, for patients with multiple studies. Descriptive statistics, univariable, and multivariable models were evaluated, and odds ratios and 95% confidence intervals are expressed below as (OR, CI).

Results

556 infants were included in the overall study, 59 had PH on their final echocardiogram (11%). In multivariable analyses, atrial septal defect (2.9, 1.4–6.1), and intrauterine growth restriction (2.7, 1.2–6.3) increased the odds of late PH, whereas caffeine therapy decreased PH (0.4, 0.2–0.8). When the analyses were restricted to 32 infants who had multiple echocardiograms during their hospitalization, the association between atrial septal defect (5.9, 2.0–16.5) and growth restriction (3.7, 1.3–10.7) and late PH was strengthened, but the effect of caffeine therapy was no longer significant. In this smaller subgroup, infants with late PH had their final echocardiogram at a median of 116 days of life, and 42–74% of them had right ventricular pathology.

Conclusions

Early clinical variables are associated with PH persistence in a referral neonatal population. Identification of early clinical factors may help guide the ascertainment of infant risk for late PH, and may aid in targeting sub-groups that are most likely to benefit from PH screening.

Trends in caffeine use and association between clinical outcomes and timing of therapy in very low birth weight infants

OBJECTIVE

To examine the effect of early initiation of caffeine therapy on neonatal outcomes and characterize the use of caffeine therapy in very low birth weight (VLBW) infants.

STUDY DESIGN

We analyzed a cohort of 62 056 VLBW infants discharged between 1997 and 2010 who received caffeine therapy. We compared outcomes in infants receiving early caffeine therapy (initial dose before 3 days of life) and those receiving late caffeine therapy (initial dose at or after 3 days of life) through propensity scoring using baseline and early clinical variables. The primary outcome was the association between the timing of caffeine initiation and the incidence of bronchopulmonary dysplasia (BPD) or death.

RESULTS

We propensity score-matched 29 070 VLBW infants at a 1:1. Of infants receiving early caffeine therapy, 3681 (27.6%) died or developed BPD, compared with 4591 infants (34.0%) receiving late caffeine therapy (OR, 0.74; 99% CI, 0.69-0.80). Infants receiving early caffeine had a lower incidence of BPD (23.1% vs 30.7%; OR, 0.68; 95% CI, 0.63-0.73) and a higher incidence of death (4.5% vs 3.7%; OR, 1.23; 95% CI, 1.05-1.43). Infants receiving early caffeine therapy had less treatment of patent ductus arteriosus (OR, 0.60; 95% CI, 0.55-0.65) and a shorter duration of mechanical ventilation (mean difference, 6 days; P < .001).

CONCLUSION

Early caffeine initiation is associated with a decreased incidence of BPD. Randomized trials are needed to determine the efficacy and safety of early caffeine prophylaxis in VLBW infants.

Hyperoxia induces alveolar epithelial-to-mesenchymal cell transition

Myofibroblast accumulation is a pathological feature of lung diseases requiring oxygen therapy. One possible source for myofibroblasts is through the epithelial-to-mesenchymal transition (EMT) of alveolar epithelial cells (AEC). To study the effects of oxygen on alveolar EMT, we used RLE-6TN and ex vivo lung slices and found that hyperoxia (85% O2, H85) decreased epithelial proteins, presurfactant protein B (pre-SpB), pro-SpC, and lamellar protein by 50% and increased myofibroblast proteins, α-smooth muscle actin (α-SMA), and vimentin by over 200% (P < 0.05). In AEC freshly isolated from H85-treated rats, mRNA for pre-SpB and pro-SpC was diminished by ∼50% and α-SMA was increased by 100% (P < 0.05). Additionally, H85 increased H2O2 content, and H2O2 (25-50 μM) activated endogenous transforming growth factor-β1 (TGF-β1), as evident by H2DCFDA immunofluorescence and ELISA (P < 0.05). Both hyperoxia and H2O2 increased SMAD3 phosphorylation (260% of control, P < 0.05). Treating cultured cells with TGF-β1 inhibitors did not prevent H85-induced H2O2 production but did prevent H85-mediated α-SMA increases and E-cadherin downregulation. Finally, to determine the role of TGF-β1 in hyperoxia-induced EMT in vivo, we evaluated AEC from H85-treated rats and found that vimentin increased ∼10-fold (P < 0.05) and that this effect was prevented by intraperitoneal TGF-β1 inhibitor SB-431542. Additionally, SB-431542 treatment attenuated changes in alveolar histology caused by hyperoxia. Our studies indicate that hyperoxia promotes alveolar EMT through a mechanism that is dependent on activation of TGF-β1 signaling.

Early caffeine therapy and clinical outcomes in extremely preterm infants

OBJECTIVE

To determine if early caffeine (EC) therapy is associated with decreased bronchopulmonary dysplasia (BPD) or death, decreased treatment of patent ductus arteriosus (PDA), or shortened duration of ventilation.

STUDY DESIGN

In a retrospective cohort of 140 neonates ≤1250 g at birth, infants receiving EC (initiation <3 days of life) were compared with those receiving late caffeine (LC, initiation ≥3 days of life) using logistic regression.

RESULT

Of infants receiving EC, 25% (21/83) died or developed BPD compared with 53% (30/57) of infants receiving LC (adjusted odds ratio (aOR) 0.26, 95% confidence interval (CI) 0.09 to 0.70; P<0.01). PDA required treatment in 10% of EC infants versus 36% of LC infants (aOR 0.28, 95%CI 0.10 to 0.73; P=0.01). Duration of mechanical ventilation was shorter in infants receiving EC (EC, 6 days; LC, 22 days; P<0.01).

CONCLUSION

Infants receiving EC therapy had improved neonatal outcomes. Further studies are needed to determine if caffeine prophylaxis should be recommended for preterm infants.

Nitric oxide attenuates epithelial-mesenchymal transition in alveolar epithelial cells

Patients with interstitial lung diseases, such as idiopathic pulmonary fibrosis (IPF) and bronchopulmonary dysplasia (BPD), suffer from lung fibrosis secondary to myofibroblast-mediated excessive ECM deposition and destruction of lung architecture. Transforming growth factor (TGF)-β1 induces epithelial-mesenchymal transition (EMT) of alveolar epithelial cells (AEC) to myofibroblasts both in vitro and in vivo. Inhaled nitric oxide (NO) attenuates ECM accumulation, enhances lung growth, and decreases alveolar myofibroblast number in experimental models. We therefore hypothesized that NO attenuates TGF-β1-induced EMT in cultured AEC. Studies of the capacity for endogenous NO production in AEC revealed that endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) are expressed and active in AEC. Total NOS activity was 1.3 pmol·mg protein−1·min−1 with 67% derived from eNOS. TGF-β1 (50 pM) suppressed eNOS expression by more than 60% and activity by 83% but did not affect iNOS expression or activity. Inhibition of endogenous NOS with l-NAME led to spontaneous EMT, manifested by increased α-smooth muscle actin (α-SMA) expression and a fibroblast-like morphology. Provision of exogenous NO to TGF-β1-treated AEC decreased stress fiber-associated α-SMA expression and decreased collagen I expression by 80%. NO-treated AEC also retained an epithelial morphology and expressed increased lamellar protein, E-cadherin, and pro-surfactant protein B compared with those treated with TGF-β alone. These findings indicate that NO serves a critical role in preserving an epithelial phenotype and in attenuating EMT in AEC. NO-mediated regulation of AEC fate may have important implications in the pathophysiology and treatment of diseases such as IPF and BPD.