BPD Infants Research Articles

A comprehensive study on machine learning models combining with oversampling for bronchopulmonary dysplasia-associated pulmonary hypertension in very preterm infants

BackgroundBronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) remains a devastating clinical complication seriously affecting the therapeutic outcome of preterm infants. Hence, early prevention and timely diagnosis prior to pathological change is the key to reducing morbidity and improving prognosis. Our primary objective is to utilize machine learning techniques to build predictive models that could accurately identify BPD infants at risk of developing PH.MethodsThe data utilized in this study were collected from neonatology departments of four tertiary-level hospitals in China. To address the issue of imbalanced data, oversampling algorithms synthetic minority over-sampling technique (SMOTE) was applied to improve the model.ResultsSeven hundred sixty one clinical records were collected in our study. Following data pre-processing and feature selection, 5 of the 46 features were used to build models, including duration of invasive respiratory support (day), the severity of BPD, ventilator-associated pneumonia, pulmonary hemorrhage, and early-onset PH. Four machine learning models were applied to predictive learning, and after comprehensive selection a model was ultimately selected. The model achieved 93.8% sensitivity, 85.0% accuracy, and 0.933 AUC. A score of the logistic regression formula greater than 0 was identified as a warning sign of BPD-PH.ConclusionsWe comprehensively compared different machine learning models and ultimately obtained a good prognosis model which was sufficient to support pediatric clinicians to make early diagnosis and formulate a better treatment plan for pediatric patients with BPD-PH.

Retrospective study of serial polysomnograms of bronchopulmonary dysplasia patients with oxygen dependence.

This retrospective study describes characteristics of serial polysomnograms (PSGs) of BPD patients on home oxygen therapy and describes PSG parameters associated with discontinuation of supplemental oxygen. A single-center study was performed at Children's Hospital Los Angeles, where serial PSGs for 44 patients with BPD infants discharged on home oxygen therapy were extracted for maximum of five PSGs or until oxygen discontinuation. Clinical and polysomnography data was collected. Characteristics of PSG1 were compared amongst the patients who were weaned from oxygen after PSG2 and PSG3. Of 44 patients, 68.2% of patients were males with median birth gestational age of 26 weeks (IQR: 24.6-28.1), median birthweight of 777.5 g(IQR: 632.5-1054 g) and 77.3% of the cohort had severe BPD. A total of 138 PSGs were studied between all 44 patients serially. When comparing PSG1 and PSG2 parameters, statistically significant improvement was noted in multiple parameters. Median baseline SpO2, peak RR, and average PETCO2 were found to be potential predictors of prolonged oxygen use. Gestational age and birth weight were not associated with prolonged oxygen use after PSG3. The median age of oxygen discontinuation was calculated to be about 2 years of age. The severity of hypoxia and tachypnea on initial infant PSG are associated with prolonged oxygen therapy past 2 years of age. Growth and development of lungs with maturation of control of breathing help improve these parameters over time regardless of BPD severity. The study may inform discussions between providers and parents for patients discharged home on oxygen therapy.

The Airway Microbiome and Metabolome in Preterm Infants: Potential Biomarkers of Bronchopulmonary Dysplasia.

ObjectivesWe investigated the genomic and metabolic characteristics of the airway microbiome in mild, moderate, severe, and non-bronchopulmonary dysplasia (BPD) preterm infants and explored possible mechanisms underlying BPD.MethodsTwenty-eight preterm infants with gestational age ≤34 weeks and intubated within 24 h after birth were enrolled. According to the severity of BPD, the patients were divided into mild, moderate and severe BPD groups, and the non-BPD group was the control group. Tracheal aspirates (TA) were obtained at intubation and on day 7 after birth. The bacterium in the aspirates were sequenced by 16S rRNA, and the metabolomics of the aspirates were identified by high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-Q-TOF/MS). The correlation between the differential metabolite and differential bacteria was investigated using Pearson’s correlation coefficient corrected for gestational age and birth weight and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases.ResultsThere were significant differences in the diversity and composition of airway microbiome and metabolome between severe, moderate and mild BPD and non-BPD premature infants. At birth (day 1), the difference was more pronounced than at day 7. The diversity of airway microbial community decreased, the abundance of Stenotrophomonas increased, and the increased level of sn-glycerol 3-phosphoethanolamine was positively correlated with the severity of BPD. There was a significant positive correlation between the abundance of Stenotrophomonas and the level of sn-glycerol 3-phosphoethanolamine.ConclusionDecreased diversity of the airway microbiome, increased abundance of Stenotrophomonas, and increased level of sn-glycerol 3-phosphoethanolamine may have potential as biomarkers for BPD. The occurrence and severity of BPD are closely related to Stenotrophomonas, which may influence the composition of the lower airway microbiome through its metabolite sn-glycerol 3-phosphoethanolamine, and may be the triggering factor of the disease. The causal relationship needs further study.

Sequelae associated with systemic hypertension in infants with severe bronchopulmonary dysplasia

ObjectivesTo ascertain correlation between systemic hypertension and respiratory sequelae amongst infants with BPD.Study designRetrospective evaluation of six-year data compared infants with severe BPD to infants with no BPD. 7-day morning blood pressure (BP) (360−366 week) was compared with 95th centile cut-offs.Results57 infants with BPD were compared with 114 infants with no BPD. Gestation and birthweight were comparable (median [interquartile range], (27 [25, 28] vs. 26.5 weeks [25, 28], p = 0.7 and 706 g [611, 884] vs. 730 [630, 895]), p = 0.1. Number of infants having BP ≥ 95th centile was significantly higher in BPD cohort (systolic BP, 23/57 [40.3%] vs. 3/114 [2.6%], p < 0.001 & mean arterial BP, 26/57 [46%] vs. 3/114 [2.6%], p < 0.001). Amongst BPD infants, higher BP was associated with longer duration of respiratory support (median [range], 109 days [81–138] vs. 87 [58–109], p < 0.001).ConclusionsInfants with severe BPD had higher BP compared to those without BPD.

Neurodevelopmental outcomes in very preterm infants: The role of severity of Bronchopulmonary Dysplasia

ObjectiveBronchopulmonary dysplasia is a chronic respiratory disease that still affects preterm neonates; its association with neurodevelopmental (ND) impairment is already known. Different studies investigated neurodevelopmental outcomes in infants with BPD, often using the old dichotomous definition (BPD vs Non-BPD). This retrospective study aims to evaluate the role of different BPD severity grades on ND outcomes at 24 months of corrected age (CA). MethodsAll preterm infants born between 2011 and 2015 in the study hospital with a gestational age (GA) ≤ 30 weeks and discharged from our NICU were included and were divided in infants with and without BPD. Infants with BPD were divided into three severity groups as defined by NICHD/NHLBI Workshop in 2001, and were compared to their Non-BPD peers, matching them according to the same GA and year of birth. At 24 months postmenstrual age, we assessed general outcomes (growth and hospital readmissions) and neurodevelopmental outcomes (motor, developmental and sensory outcomes) with a standardized assessment. ResultsWe enrolled 89 patients affected by BPD of different grades of severity and a control group of 89 preterm infants without BPD.Infants with Moderate and Severe BPD showed a significantly higher corrected odds ratio (OR) for cognitive impairment compared to controls. Within the group of infants without severe disability (regarding Griffiths' scales), infants with Moderate and Severe BPD as well as infants with Mild BPD showed a significantly higher risk of a lower total Developmental Quotient (DQ) score, even after correction for confounding factors. ConclusionsOur study evidenced that not only Severe BPD infants, but also Moderate ones showed a higher risk of overall cognitive impairment at 24 months CA. Within the group of infants without severe disability, also those with Mild BPD had lower Griffiths DQ scores than those without. This would suggest that infants with BPD, regardless of severity, warrant neurodevelopmental follow-up.

Interleukin-1 Receptor Antagonist Protects Newborn Mice Against Pulmonary Hypertension.

Pulmonary hypertension secondary to bronchopulmonary dysplasia (BPD-PH) represents a major complication of BPD in extremely preterm infants for which there are currently no safe and effective interventions. The abundance of interleukin-1 (IL-1) is strongly correlated with the severity and long-term outcome of BPD infants and we have previously shown that IL-1 receptor antagonist (IL-1Ra) protects against murine BPD; therefore, we hypothesized that IL-1Ra may also be effective against BPD-PH. We employed daily injections of IL-1Ra in a murine model in which BPD/BPD-PH was induced by antenatal LPS and postnatal hyperoxia of 65% O2. Pups reared in hyperoxia for 28 days exhibited a BPD-PH-like disease accompanied by significant changes in pulmonary vascular morphology: micro-CT revealed an 84% reduction in small vessels (4–5 μm diameter) compared to room air controls; this change was prevented by IL-1Ra. Pulmonary vascular resistance, assessed at day 28 of life by echocardiography using the inversely-related surrogate marker time-to-peak-velocity/right ventricular ejection time (TPV/RVET), increased in hyperoxic mice (0.27 compared to 0.32 in air controls), and fell significantly with daily IL-1Ra treatment (0.31). Importantly, in vivo cine-angiography revealed that this protection afforded by IL-1Ra treatment for 28 days is maintained at day 60 of life. Despite an increased abundance of mediators of pulmonary angiogenesis in day 5 lung lysates, namely vascular endothelial growth factor (VEGF) and endothelin-1 (ET-1), no difference was detected in ex vivo pulmonary vascular reactivity between air and hyperoxia mice as measured in precision cut lung slices, or by immunohistochemistry in alpha-smooth muscle actin (α-SMA) and endothelin receptor type-A (ETA) at day 28. Further, on day 28 of life we observed cardiac fibrosis by Sirius Red staining, which was accompanied by an increase in mRNA expression of galectin-3 and CCL2 (chemokine (C-C motif) ligand 2) in whole hearts of hyperoxic pups, which improved with IL-1Ra. In summary, our findings suggest that daily administration of the anti-inflammatory IL-1Ra prevents the increase in pulmonary vascular resistance and the pulmonary dysangiogenesis of murine BPD-PH, thus pointing to IL-1Ra as a promising candidate for the treatment of both BPD and BPD-PH.

Defining T helper cell immunity in bronchopulmonary dysplasia

Abstract Background Bronchopulmonary dysplasia (BPD) is a common neonatal lung disease that has been linked to pulmonary inflammation. Previous studies have suggested involvement of various cell types and soluble factors but have thus far failed to reveal a dominant pathway that underpins disease progression. It remains unknown that which T helper (Th) cell polarization, if any, contributes to the pathogenesis of BPD. Methods Citrated whole cord and peripheral blood were collected from infants born between 24+0–28+6 gestational weeks at five different time points, namely at birth, on days 1, 7 and 14 and at 36 weeks corrected gestational age (CGA). Cells were stimulated with either PMA, ionomycin and brefeldin A or vehicle and brefeldin A overnight. Cells were then stained for multi-color flow cytometry to enumerate Th cell subsets including Th1, Th2 and Th17 and regulatory T cells. Results were analyzed against BPD disease status at 36 weeks CGA and corrected for confounders. Results 50 infants were enrolled and 228 unique samples were collected. 36 enrolled infants (72%) had BPD (mild to severe) at 36 weeks CGA. When compared to infants that did not have the disease, the frequency of interleukin(IL)-4 in CD4+ Th cells in peripheral blood was increased in infants with BPD on days 1 (p=0.0449), 7 (p=0.0423), 14 (p=0.0489) and 36 weeks CGA but not within cord blood. There was no difference in the frequency of cells positive for interferon-gamma (IFNγ), IL-17A or FOXP3 among CD4+ cells in blood from BPD and non-BPD infants across all time points. Conclusions T helper cells are polarized towards a Th2 phenotype in infants with BPD based on elevated levels of IL-4 in CD4+ cells. We hypothesize that BPD infants may benefit from therapies that target the Th2 pathway.

PS-274 Lack Of Association Between Bronchopulmonary Dysplasia And Gastro-esophageal Reflux At Esophageal Ph-impedentiometry: A Prospective Study In Symptomatic Preterm Infants

Background and aims The role of GER in the pathogenesis and recovery from BPD in preterm infants is controversial; some Authors suggested symptomatic GER treatment for BPD infants. We tested the hypothesis that BPD predisposes to GER (due to increased respiratory effort, coughing and crying). Methods We prospectively studied 44 infants born 2-analysis and t-test/Mann-Whitney test were performed to look for differences among the two groups; P value of Results Demographic and clinical characteristics between BPD and controls were similar: GA 201 vs 202 days, male sex 66.7 vs 46.9%, age at study 51 vs 39 days, orogastric tube feeding 83.3% vs 75%, caffeine administration 33.3% vs 50% (all P > 0.05). The analysis of 1056 h of Ph-MII tracings showed no significant difference between BPD and controls regarding the median number of these parameters: acid (3 vs 2), weakly acid (11 vs 16), non-acid (0 vs 0), gas (7 vs 10) refluxes, ph-only events (21 vs 9), GER >5 min (1.5 vs 3.5); longest GER (11.2 vs 16.5 min), lower ph (1.5 vs 2.1), acid exposure (ph 0.05). Conclusions In our experience, BPD was not associated with higher reflux parameters as measured by 24 h Ph-MII examinations among preterm infants. Symptomatic GER treatment with drugs should be reserved for confirmed pathologic Ph-MII tests in order to avoid adverse events.

Placental pathologic changes of maternal vascular underperfusion in bronchopulmonary dysplasia and pulmonary hypertension

IntroductionBronchopulmonary dysplasia (BPD) is the most common chronic lung disease of infancy, and BPD-associated pulmonary hypertension (PH) is a serious complication that can negatively impact later childhood health. There is growing evidence that lung injury leading to BPD and PH is due to chronic fetal hypoxia-ischemia. The purpose of this study was to investigate whether placental pathologic changes of maternal vascular underperfusion (MVU) are associated with BPD, and further increased with PH. MethodsWe conducted a 5-year retrospective cohort study of premature infants born ≤28 weeks. BPD was defined as persistent oxygen requirement at 36 weeks corrected gestational age. PH was identified using a standardized algorithm of echocardiogram review. Archived placental slides underwent standardized masked histopathologic review. Logistic regression modeling was performed, taking into account important maternal and infant covariates. ResultsAmong 283 births, 121 had MVU, of which 67 (55%) developed BPD, and 24 (20%) had PH. Among the common neonatal complications of extreme prematurity, BPD was the only outcome that was increased with MVU (P < 0.001). After adjustment for birth weight, fetal growth restriction, preeclampsia and other factors, infants with MVU were more likely to develop BPD (adjusted odds ratio = 2.6; 95% confidence interval = 1.4, 4.8). Certain MVU sublesions (fibrinoid necrosis/acute atherosis and distal villous hypoplasia/small terminal villi) were increased with PH (P < 0.001). DiscussionPlacental MVU may identify BPD infants who were exposed to intrauterine hypoxia-ischemia, which increases their risk for development of PH disease. ConclusionsOur findings have important implications for providing earlier and more effective therapies for BPD.

Sleeping position, oxygenation and lung function in prematurely born infants studied post term

Objective:To determine the effect of sleeping position on the lung function of prematurely born infants when post term, whether any effect was similar to that before discharge from the neonatal...

Weight growth velocity of very low birth weight infants: role of gender, gestational age and major morbidities

It's well known that VLBWI fail to thrive, however it's still unclear how gender, GA and morbidities affect growth pattern: aim of this study is to assess the influence of these factors on weight growth. 262 VLBWI were selected. Weight was recorded daily up to 28 days, weekly up to discharge and during 7 scheduled follow-up visits up to 2 years of corrected age. Individual profiles were fitted with a mathematical function suitable to model selected growth milestones and mean distance and velocity curves were drawn. Effects of gender, GA, major-morbidities, nutritional and respiratory support on individual weight growth milestones were estimated using a multivariate linear model. Each of these variables acts differently on weight growth pattern mainly modifying velocity curves characteristics. In particular, infants with major morbidities weight growth impairment–seen on distance curves at 2 years of corrected age–depends on poor weight velocity during a critical period ending within 4th month of postnatal age, for SGA or BPD infants, starting from 5th month of postnatal for severely neurologically impaired infants. These critical periods could be the most appropriate to identify risk factors for weight growth impairment in VLBWI.

Chest radiograph thoracic areas and lung volumes in infants developing bronchopulmonary dysplasia

To determine whether chest radiograph (CXR) thoracic areas and lung volumes differed between infants who did and did not develop BPD and according to the severity of BPD developed. Infants developing BPD, particularly if moderate or severe, would have low CXR thoracic areas and lung volumes in the perinatal period. Prospective study. PATIENT-SUBJECT SELECTION: 53 infants with a median gestational age of 28 (range 24-32) weeks. CXR thoracic areas were calculated using a Picture Archiving and Communicating System (PACS) and lung volume assessed by measurement of functional residual capacity (FRC) in the first 72 hr after birth. BPD was diagnosed if the infants were oxygen dependent beyond 28 days, mild BPD in infants no longer oxygen dependent at 36 weeks post-menstrual age (PMA) and moderate/severe BPD in infants who required supplementary oxygen with or without respiratory support at 36 weeks PMA. Thirty two infants developed BPD, 21 had moderate/severe BPD. The median CXR thoracic areas were higher (P < 0.0001) and FRCs were lower (P < 0.0001) in the BPD compared to no BPD infants. The median CXR thoracic areas of the moderate/severe group (P < 0.001) and the mild group (P < 0.05) were greater than that of the no BPD group and the median FRC of the moderate/severe BPD group was lower than the no BPD group (<0.001) and the mild BPD group (P < 0.05). These results highlight that in the perinatal period infants developing BPD, particularly if moderate/severe, have low functional lung volumes and may have gas trapping, which likely reflects ventilation inhomogeneity.

Survey of neonatal respiratory support strategies

To survey current practice regarding neonatal respiratory support strategies to determine whether it reflected evidence from randomised trials. A questionnaire (in Supplementary Material online) survey of all U.K. neonatal units was undertaken to determine what modes of ventilation, types of endotracheal tube, lung function monitoring and oxygen saturation levels were used. There was an 80% response rate. Most (73%) units used in prematurely born infants (in the first 24 h) the intermittent positive pressure ventilation, and other respiratory modes included: CPAP (2%), triggered ventilation with or without volume guarantee (22%) and high frequency oscillation (2%). Only 15% of units used assist control mode for weaning; the preferred weaning mode was synchronous intermittent mandatory ventilation (73%). Few units used shouldered endotracheal tubes (3%) or lung function measurements (25%) to aid choice of ventilator settings. Oxygen saturation levels from 80% to 98% were used, levels greater or equal to 95% were used by 11% of units for infants with acute respiratory disease but by 34% of units for BPD infants (p < 0.001). Many practitioners do not base their choice of neonatal respiratory support strategies on the results of large randomised trials; more effective methods are required to ensure evidence-based practice.

Bronchopulmonary dysplasia – Long term follow up

Fifty percent of BPD infants require readmission to hospital during infancy, particularly if they suffer an RSV infection. Many BPD infants require supplementary oxygen at home, early discharge can be achieved if those still requiring nasogastric feeding are given appropriate community support. Troublesome respiratory symptoms are common in children who had BPD, as are lung function abnormalities even in adolescents and young adults.

Home oxygen therapy in infants with bronchopulmonary dysplasia: a prospective study.

We followed the clinical course of 21 infants with bronchopulmonary dysplasia enrolled in a prospective home O2 therapy programme during a 4-year-period. Mean gestational age was 28.5 weeks (range, 25-36 weeks) and mean birth weight 1093 g (range 630-2750 g). Infants were regularly monitored to maintain pulse oximeter O2 saturation over 94%-95%. The source of O2 was liquid oxygen and was delivered by nasal cannula. During the follow up oxygenation was assessed by SatO2 measurement, cardiac function by Doppler echocardiography and respiratory function by the occlusion technique. All patients had an ophthalmological follow up. The mean age of the infants at discharge was 3.7 months (range 1.7-8.6) and mean weight 2830 g (range 2150-3780 g). At discharge 8 infants had right ventricular hypertrophy (RVH) and four of them had pulmonary hypertension. Mean duration of home O2 therapy was 97 days (range 15-320 days) and the mean age of discontinuation of O2 was 6.9 months (range 3-14.7 months). The cardiological follow up was benign: the ECG signs of RVH disappeared by 12 months of age in six out of eight infants and the right ventricular pulmonary pressure, as measured by the Doppler method, normalised in the four patients in whom it was detected. No relationship was found between respiratory mechanics and the duration of O2 therapy. Weight gain was poor with mean growth at the 3rd percentile for females and just below the 3rd percentile for males. Twelve of the 21 infants required 25 rehospitalizations. No one presented deterioration of retinopathy of prematurity that was present in 16 infants at discharge; at 12 months retinopathy was resolved in 14 infants. A total of 2025 hospital days were saved, representing a significant financial saving. Home O2 therapy permits the safe early discharge of O2-dependent BPD infants and it reduces significantly the length of time spent in hospital which represents a considerable financial saving.

RESPIRATORY STATUS, TOTAL ENERGY EXPENDITURE, AND GROWTH IN INFANTS WITH BRONCHOPULMONARY DYSPLASIA 1967

Growth failure was studied in infants with BPD by relating their nutritional balance and growth to past and current clinical status. Total daily energy expenditure (TEE) was measured with doubly labeled water in 9 preterm infants with BPD receiving supplemental oxygen (all male, age 61±13 days) and 9 matched controls (5 male, age 36 ±21 days) during a 6 day period. Energy and protein balance, and growth were assessed as well. TEE was higher in the BPD infants compared to controls (73 ±9 vs. 63 ±8 kcal/kg/day, P < 0.05), but faecal energy loss in BPD infants was lower (P < 0.01). Weight gain, energy intake, energy cost of growth, protein retention, and physical activity were not different. The respiratory frequency (RR) in the BPD infants was elevated in comparison with controls (P< 0.01); within the BPD group RR was significantly associated with energy expenditure (r2 = 0.82, P < 0.001). The fitted equation was TEE[kcal/kg/day] = 26.3 + 0.71*RR [min-1]. We conclude that total energy expenditure in BPD infants is elevated, and is strongly associated with their respiratory status. These findings support the use of high-energy feeding for the nutritional management in infants with severe BPD.

THREE YEAR OUTCOME OF INFANTS WITH BRONCHOPULMONARY DYSPLASIA (BPD) AND VERY LOW BIRTHWEIGHT. † 1666

In a regional cohort, we investigated the relationship of BPD, relative to other perinatal risk factors, to developmental outcome at 3 years. Infants with BPD (n=122), VLBW without BPD (84), and term (T) infants (123) were given the Bayley Scales at 3 years. Groups did not differ in sex, race, SES, age. Drug exposed infants were excluded. BPD infants had more perinatal risk factors, i.e. lower GA, BW, more IVH, neurologic problems, sepsis and ROP,(p's <.05). Both mental (84 ± 24 v. 90 ± 16 v. 96 ± 12), and motor (84 ± 29 v. 98 ± 20 v. 103 ± 15, p's<.001) scores were lower for BPD children. Using multiple regression controlling for all other risk factors, BPD had an independent negative effect on motor outcome (p <.02), with neurologic risk and BPD the only significant predictors of motor delay, accounting for 25% (p <.001) of the variance. In contrast, social class, race and neurologic risk were the only significant predictors of cognitive outcome. The effect of SES on cognitive outcome was evident in differential rates of mental retardation within the BPD group. In the lowest SES group (IV-V) 26% of children were thus classified, vs. 14% in the middle/high SES group (I-III). This rate contrasts with 19% of VLBW infants thus classified in the lowest SES group vs. 2% in the middle/high SES groups, and 7% of term, low SES children vs. 3% of middle/high SES children. These findings suggest that the effects of BPD are primarily on the motor domain, and demonstrate the importance of postnatal factors and intervention on cognitive outcome. (HL38193, MCJ 390592).

Mental and motor development for three groups of premature infants

The purpose of this experiment was to contrast three groups of premature infants on 4-and 8-month cognitive and motor development. Premature infants diagnosed with bronchopulmonary dysplasia (BPD; n = 21) and respiratory distress syndrome (RDS; n = 17) were recruited from a regional medical center along with a group of healthy prematures (well; n = 10). Well infants outperformed RDS infants, who, in turn, outperformed BPD infants on cognitive assessments at 4 and 8 months. Both well and RDS infants scored higher than BPD infants on motor development at 4 and 8 months. Suggestions for future research efforts are offered.

1784 MOVEMENT DISTURBANCES OF INFANTS WITH BRONCHOPULMONARY DYSPLASIA (BPD)

Infants with BPD frequently have patterns of shoulder girdle retraction and cervical hyperextension which may interfere with midline movement. Therefore we compared arm movement, head control, and cardiorespiratory changes in response to movement and handling in 10 infants with BPD at 16 weeks corrected age to that of 11 normal age-matched infants. Arm responses to midline stimuli, retention of primary reflexes, scapular and cervical muscle tone in supine and prone were scored based on direct observation and analysis of videotape recordings. The mean weight of the BPD infants was 78% of that of the controls (BPD=4925±739g vs 6278±31g; M±SD, p <0.001). The BPD infants had respiratory rates 35% higher than the controls (mean=48 vs 35.5, p< 0.05). No significant changes occurred in heart rate, respiratory rate or TcPO2, indicating both groups tolerated the procedure equally well. Arm midline activity of the control infants was 2-fold greater than that of the BPD group (p <0.05). Prone head control and trunk support were developed twice as well in the controls than BPD infants (p <0.05). Significant retention of the spontaneous asymmetrical tonic neck reflex and grasp reflex observed in the BPD infants was not present in the controls (p <0.05). Muscle tone was similar in both groups. We speculate that BPD infants may curb movement in order to reserve energy for increased work of breathing.

1525 GASTROESOPHAGEAL REFLUX (GER) TO THE PROXIMAL ESOPHAGUS IN NEONATES WITH BRONCHOPULMONARY DYSPLASIA

Recurrent aspiration following GER may contribute to the severity of chronic lung disease. If so, it should be possible to document acid reflux to the proximal esophagus. Using an esophageal pH probe placed at the level of the 1st or 2nd thoracic vertebra, we evaluated GER in 11 infants with BPD and 9 infants with no BPD. Results (meant±SD):Control infants have frequent episodes of GER to the upper esophagus but either do not aspirate or are not embarrassed by small aspirations. Infants with BPD have significantly less GER to the proximal esophagus than non BPD babies. The reason for this is not apparent. Either GER in BPD infants is unimportant or aspiration may follow occasional episodes of GER causing severe bronchospasm as well as aggravating existing lung disease.