Namasivayam Ambalavanan

Dr. Namasivayam Ambalavanan


Research Focus & Metrics

Academic Career Length

39Years (1988-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2009 in Pediatrics
Verified
Journal Article
Closed access
PDF file
CCCharles Michael Cotten
Charles Michael Cotten
STSarah Taylor
Sarah Taylor
BSBarbara Stoll
Barbara Stoll
RGRonald N. Goldberg
Ronald N. Goldberg
NHNellie I. Hansen
Nellie I. Hansen
FNfor the NICHD Neonatal Research Network
for the NICHD Neonatal Research Network
OBJECTIVES. Our objectives were to identify factors associated with the duration of the first antibiotic course initiated in the first 3 postnatal days and to assess associations between the duration of the initial antibiotic course and subsequent necrotizing enterocolitis or death in extremely low birth weight infants with sterile initial postnatal culture results. METHODS. We conducted a retrospective cohort analysis of extremely low birth weight infants admitted to tertiary centers in 1998–2001. We defined initial empirical antibiotic treatment duration as continuous days of antibiotic therapy started in the first 3 postnatal days with sterile culture results. We used descriptive statistics to characterize center practice, bivariate analyses to identify factors associated with prolonged empirical antibiotic therapy (≥5 days), and multivariate analyses to evaluate associations between therapy duration, prolonged empirical therapy, and subsequent necrotizing enterocolitis or death. RESULTS. Of 5693 extremely low birth weight infants admitted to 19 centers, 4039 (71%) survived >5 days, received initial empirical antibiotic treatment, and had sterile initial culture results through the first 3 postnatal days. The median therapy duration was 5 days (range: 1–36 days); 2147 infants (53%) received prolonged empirical therapy (center range: 27%–85%). Infants who received prolonged therapy were less mature, had lower Apgar scores, and were more likely to be black. In multivariate analyses adjusted for these factors and center, prolonged therapy was associated with increased odds of necrotizing enterocolitis or death and of death. Each empirical treatment day was associated with increased odds of death, necrotizing enterocolitis, and the composite measure of necrotizing enterocolitis or death. CONCLUSION. Prolonged initial empirical antibiotic therapy may be associated with increased risk of necrotizing enterocolitis or death and should be used with caution.

15 June 2011 in American Journal of Respiratory and Critical Care Medicine
Verified
Journal Article
Closed access
MLMatthew M. Laughon
Matthew M. Laughon
JLJohn C. Langer
John C. Langer
CBCarl L. Bose
Carl L. Bose
PSP. Brian Smith
P. Brian Smith
NANamasivayam Ambalavanan
Namasivayam Ambalavanan
MWMichele C. Walsh
Michele C. Walsh
Rationale: Benefits of identifying risk factors for bronchopulmonary dysplasia in extremely premature infants include providing prognostic information, identifying infants likely to benefit from preventive strategies, and stratifying infants for clinical trial enrollment. Objectives: To identify risk factors for bronchopulmonary dysplasia, and the competing outcome of death, by postnatal day; to identify which risk factors improve prediction; and to develop a Web-based estimator using readily available clinical information to predict risk of bronchopulmonary dysplasia or death. Methods: We assessed infants of 23–30 weeks' gestation born in 17 centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network and enrolled in the Neonatal Research Network Benchmarking Trial from 2000–2004. Measurements and Main Results: Bronchopulmonary dysplasia was defined as a categorical variable (none, mild, moderate, or severe). We developed and validated models for bronchopulmonary dysplasia risk at six postnatal ages using gestational age, birth weight, race and ethnicity, sex, respiratory support, and FiO2, and examined the models using a C statistic (area under the curve). A total of 3,636 infants were eligible for this study. Prediction improved with advancing postnatal age, increasing from a C statistic of 0.793 on Day 1 to a maximum of 0.854 on Day 28. On Postnatal Days 1 and 3, gestational age best improved outcome prediction; on Postnatal Days 7, 14, 21, and 28, type of respiratory support did so. A Web-based model providing predicted estimates for bronchopulmonary dysplasia by postnatal day is available at https://neonatal.rti.org. Conclusions: The probability of bronchopulmonary dysplasia in extremely premature infants can be determined accurately using a limited amount of readily available clinical information.

1 March 2012 in Pediatrics
Verified
Journal Article
Closed access
PDF file
RBRamachandra Bhat
Ramachandra Bhat
ASAriel A. Salas
Ariel A. Salas
CFChris Foster
Chris Foster
WCWaldemar A. Carlo
Waldemar A. Carlo
NANamasivayam Ambalavanan
Namasivayam Ambalavanan
OBJECTIVES: Pulmonary hypertension is associated with bronchopulmonary dysplasia in extremely low birth weight (ELBW) infants and contributes to morbidity and mortality. The objective was to determine the prevalence of pulmonary hypertension among ELBW infants by screening echocardiography and evaluate subsequent outcomes. METHODS: All ELBW infants admitted to a regional perinatal center were evaluated for pulmonary hypertension with echocardiography at 4 weeks of age and subsequently if clinical signs suggestive of right-sided heart failure or severe lung disease were evident. Management was at discretion of the clinician, and infants were evaluated until discharge from the hospital or pre-discharge death occurred. RESULTS: One hundred forty-five ELBW infants (birth weight: 755 ± 144 g; median gestational age: 26 weeks [interquartile range: 24–27]) were screened from December 2008 to February 2011. Overall, 26 (17.9%) were diagnosed with pulmonary hypertension at any time during hospitalization (birth weight: 665 ± 140 g; median gestational age: 26 weeks [interquartile range: 24–27]): 9 (6.2%) by initial screening (early pulmonary hypertension) and 17 (11.7%) who were identified later (late pulmonary hypertension). Infants with pulmonary hypertension were more likely to receive oxygen treatment on day 28 compared with those without pulmonary hypertension (96% vs 75%, P < .05). Of the 26 infants, 3 died (all in the late group because of cor pulmonale) before being discharged from the hospital. CONCLUSIONS: Pulmonary hypertension is relatively common, affecting at least 1 in 6 ELBW infants, and persists to discharge in most survivors. Routine screening of ELBW infants with echocardiography at 4 weeks of age identifies only one-third of the infants diagnosed with pulmonary hypertension. Further research is required to determine optimal detection and intervention strategies.

24 October 2017 in JAMA
Verified
Journal Article
Open access
PDF file
ALAbbot R. Laptook
Abbot R. Laptook
SSSeetha Shankaran
Seetha Shankaran
JTJon E. Tyson
Jon E. Tyson
BMBreda Munoz
Breda Munoz
EBEdward F. Bell
Edward F. Bell
HNHuman Development Neonatal Research Network
Human Development Neonatal Research Network
Quiz Ref ID Hypoxic-ischemic encephalopathy represents a subset of neonatal encephalopathy, occurring in approximately 1.5 per 1000 live births.1 It is an important etiology of neonatal mortality and serious or devastating lifelong cerebral palsy, neurosensory deficits, and cognitive impairments.2 Therapeutic hypothermia initiated within 6 hours after birth for moderate or severe hypoxic-ischemic encephalopathy reduced the composite outcome of death or disability at 18 months in multiple randomized clinical trials3-8 and improved outcomes at 6 to 7 years.9,10 The American Academy of Pediatrics published a framework to ensure appropriate use of hypothermia.11

1 November 2018 in Matrix Biology
Verified
Journal Article
Closed access
YZYong Zhou
Yong Zhou
JHJeffrey C. Horowitz
Jeffrey C. Horowitz
Alexandra NabaAlexandra Naba
Alexandra Naba
NANamasivayam Ambalavanan
Namasivayam Ambalavanan
KAKamran Atabai
Kamran Atabai
VTVictor J. Thannickal
Victor J. Thannickal

1 February 2009 in Pediatric Nephrology
Verified
Journal Article
Open access
PDF file
DADavid J. Askenazi
David J. Askenazi
NANamasivayam Ambalavanan
Namasivayam Ambalavanan
SGStuart L. Goldstein
Stuart L. Goldstein
Outcomes in critically ill neonates have improved over the past three decades, yet high residual mortality and morbidity rates exist. Acute kidney injury (AKI) is not just an innocent by-stander in the critically ill patient. Research on incidence and outcomes of AKI in the critically ill neonatal population is scarce. The objective of this publication is to (a) review original articles on the short- and long-term outcomes after neonatal AKI, (b) highlight key articles on adults and children with AKI in order to demonstrate how such insights might be applied to neonates, and (c) suggest clinical research studies to fill the gaps in our understanding of neonatal AKI. To date, observational studies suggest high rates of AKI and poor outcomes in critically ill neonates. Neonates with AKI are at risk of developing chronic kidney disease and hypertension. Large prospective studies are needed to test definitions and to better understand risk factors, incidence, independent outcomes, and mechanisms that lead to poor short- and long-term outcomes. Early biomarkers of AKI need to be explored in critically ill neonates. Infants with AKI need to be followed for sequelae after AKI.