Cerebrovascular responses to a 90° tilt in healthy neonates.

BACKGROUND: Tilts can induce alterations in cerebral hemodynamics in healthy neonates, but prior studies have only examined systemic parameters or used small tilt angles (<90°). The healthy neonatal population, however, are commonly subjected to large tilt angles (≥90°). We sought to characterize the cerebrovascular response to a 90° tilt in healthy term neonates. METHODS: We performed a secondary descriptive analysis on 44 healthy term neonates. We measured cerebral oxygen saturation (rcSO2), oxygen saturation (SpO2), heart rate (HR), breathing rate (BR), and cerebral fractional tissue oxygen extraction (cFTOE) over three consecutive 90° tilts. These parameters were measured for 2-min while neonates were in a supine (0°) position and 2-min while tilted to a sitting (90°) position. We measured oscillometric mean blood pressure (MBP) at the start of each tilt. RESULTS: rcSO2 and BR decreased significantly in the sitting position, whereas cFTOE, SpO2, and MBP increased significantly in the sitting position. We detected a significant position-by-time interaction for all physiological parameters. CONCLUSION: A 90° tilt induces a decline in rcSO2 and an increase in cFTOE in healthy term neonates. Understanding the normal cerebrovascular response to a 90° tilt in healthy neonates will help clinicians to recognize abnormal responses in high-risk infant populations. IMPACT: Healthy term neonates (≤14 days old) had decreased cerebral oxygen saturation (~1.1%) and increased cerebral oxygen extraction (~0.01) following a 90° tilt. We detected a significant position-by-time interaction with all physiological parameters measured, suggesting the effect of position varied across consecutive tilts. No prior study has characterized the cerebral oxygen saturation response to a 90° tilt in healthy term neonates.

Sociodemographic profile associated with congenital heart disease among infants <1 year old.

PURPOSE: Congenital heart disease affects thousands of newborns each year in the United States. Previous United States-based research has explored how sociodemographic factors may impact health outcomes in infants with congenital heart disease; however, their impact on the incidence of congenital heart disease is unclear. We explored the sociodemographic profile related to congenital heart disease to help address health disparities that arise from race and social determinants of health. Defining the sociodemographic factors associated with congenital heart disease will encourage implementation of potential preventative measures. DESIGN AND METHODS: We conducted a secondary analysis of longitudinally collected data comparing 39 infants with congenital heart disease and 30 healthy controls. We used a questionnaire to collect sociodemographic data. Pearson's chi-square test/Fisher's exact tests analyzed the associations among different sociodemographic factors between infants with congenital heart disease and healthy controls. RESULTS: We found a statistically significant difference in maternal education between our 2 groups of infants (p = 0.004). CONCLUSION: Maternal education was associated with congenital heart disease. Future studies are needed to further characterize sociodemographic factors that may predict and impact the incidence of congenital heart disease and to determine possible interventions that may help decrease health disparities regarding the incidence of congenital heart disease. PRACTICE IMPLICATIONS: Understanding the associations between maternal sociodemographic factors and infant congenital heart disease would allow clinicians to identify mothers at higher risk of having an infant with congenital heart disease.

A pilot study: Comparing a novel noninvasive measure of cerebrovascular stability index with an invasive measure of cerebral autoregulation in neonates with congenital heart disease.

Infants with congenital heart disease (CHD) may have impaired cerebral autoregulation (CA) associated with cerebral fractional tissue oxygen extraction (FTOE). We conducted a pilot study in nine CHD neonates to validate a noninvasive CA measure, cerebrovascular stability index (CSI), by eliciting responses to postural tilts. We compared CSI to an invasive measure of CA and to FTOE collected during tilts (FTOESpot). FTOESpot correlated with CSI, as did the change in FTOE during tilts, but CSI's correlation with impaired CA did not reach significance. Larger trials are indicated to validate CSI, allowing for noninvasive CA measurements and measurements in outpatient settings.

Sociodemographic Profile Associated with Congenital Heart Disease among Infants Less than 1 Year Old.

Background: Congenital heart disease (CHD) affects thousands of newborns each year in the United States (US). Infants born with CHD have an increased risk of adverse health outcomes compared to healthy infants. These outcomes include, but are not limited to, neurodevelopmental, surgical, and mortality-related outcomes. Previous US-based research has explored how sociodemographic factors may impact these health outcomes in infants with CHD; however, their impact on the risk of CHD is unclear. This study aims to explore the sociodemographic profile related to CHD to help address health disparities that arise from race and social determinants of health. Defining the sociodemographic factors associated with CHD will encourage policy change and the implementation of preventative measures. Methods: This study is a secondary analysis of longitudinally collected data. We compared infants with CHD and healthy controls. We used a questionnaire to collect sociodemographic data. Pearson's chi-square test/Fisher's exact tests analyzed the associations among different sociodemographic factors between infants with CHD and healthy controls. Results: We obtained sociodemographic factors from 30 healthy control infants and 39 infants with CHD. We found a statistically significant difference in maternal education between our 2 groups of infants (p=0.004). Conclusion: Maternal education is associated with CHD. Future studies are needed to further characterize sociodemographic factors that may predict and impact the risk of CHD and to determine possible interventions that may help decrease health disparities regarding the risk of CHD.

Molecular mechanisms underlying iron and phosphorus co-limitation responses in the nitrogen-fixing cyanobacterium Crocosphaera.

In the nitrogen-limited subtropical gyres, diazotrophic cyanobacteria, including Crocosphaera, provide an essential ecosystem service by converting dinitrogen (N2) gas into ammonia to support primary production in these oligotrophic regimes. Natural gradients of phosphorus (P) and iron (Fe) availability in the low-latitude oceans constrain the biogeography and activity of diazotrophs with important implications for marine biogeochemical cycling. Much remains unknown regarding Crocosphaera's physiological and molecular responses to multiple nutrient limitations. We cultured C. watsonii under Fe, P, and Fe/P (co)-limiting scenarios to link cellular physiology with diel gene expression and observed unique physiological and transcriptional profiles for each treatment. Counterintuitively, reduced growth and N2 fixation resource use efficiencies (RUEs) for Fe or P under P limitation were alleviated under Fe/P co-limitation. Differential gene expression analyses show that Fe/P co-limited cells employ the same responses as single-nutrient limited cells that reduce cellular nutrient requirements and increase responsiveness to environmental change including smaller cell size, protein turnover (Fe-limited), and upregulation of environmental sense-and-respond systems (P-limited). Combined, these mechanisms enhance growth and RUEs in Fe/P co-limited cells. These findings are important to our understanding of nutrient controls on N2 fixation and the implications for primary productivity and microbial dynamics in a changing ocean.