Validation of energy expenditure and macronutrient oxidation measured by two new whole-room indirect calorimeters.

OBJECTIVE: The aim of this study was to validate two new whole-room indirfect calorimeters according to Room Indirect Calorimetry Operating and Reporting Standards (RICORS 1.0). METHODS: For technical validation, 16 propane combustion tests were performed to determine accuracy and precision of energy expenditure (EE) and ventilation rates of oxygen (VO2 ), carbon dioxide (VCO2 ), and respiratory exchange ratio (VCO2 /VO2 ). For biological validation, eight participants (mean [SD], age 24.1 [2.5] years; BMI 24.3 [3.1] kg/m2 ) underwent four 24-hour protocols under highly standardized conditions: (1) isocaloric sedentary, (2) fasting sedentary, (3) isocaloric active, and (4) fasting active. Reliability (coefficients of variation [CV]) and minimal detectable changes (MDC) were calculated for 24-hour EE, sleeping metabolic rate (SMR), physical activity energy expenditure (PAEE), thermic effect of food (TEF), and macronutrient oxidation rates. RESULTS: Technical validation showed high reliability and recovery rates for VO2 (0.75% and 100.8%, respectively), VCO2 (0.49% and 100.6%), and EE (0.54% and 98.2%). Biological validation revealed CV and MDC for active conditions of 1.4% and 4.3% for 24-hour EE, 1.7% and 5.9% for SMR, and 30.2% and 38.4% for TEF, as well as 5.8% and 10.5% for PAEE, respectively. Mean CV and MDC for macronutrient oxidation rates were 9.9% and 22.9%, respectively. CONCLUSIONS: The precision of 24-hour EE and SMR was high, whereas it was lower for PAEE and poor for TEF.

The Relationship Between Clinical Imaging and Neurobehavioral Assessment in Posthemorrhagic Ventricular Dilation of Prematurity.

Introduction: Neonatal intraventricular hemorrhage (IVH) and subsequent posthemorrhagic ventricular dilation and hydrocephalus of prematurity are associated with brain injury and neurodevelopmental impairment in the preterm population. Neuroimaging assesses cerebral injury and guides neurosurgical intervention; however, the relationship of head ultrasound (HUS) and magnetic resonance imaging (MRI) parameters to neonatal exams in this group has not been well described. The NICU Network Neurobehavioral Scale (NNNS) is a reproducible, highly reliable battery with motor and cognitive domain scores. Objective: To evaluate the relationship between neonatal neurobehavioral findings on the NNNS and measures of ventricular dilation and associated brain injury on HUS and MRI. Materials and Methods: Neonates with IVH and ventricular dilatation with and without posthemorrhagic hydrocephalus were enrolled. NNNS exams were performed at approximately term age equivalent. HUS indices were measured on the last HUS before initial neurosurgical procedure or that with worst ventriculomegaly if no intervention. The posterior fossa was assessed with MRI at term. Descriptive statistics including medians, interquartile ranges, means, and percentages were performed. Correlations were estimated using Pearson's method. Results: 28 patients had NNNS and HUS, and 18 patients also had an MRI. Ventricle size measures for the cohort were significantly above normal. Motor and cognitive subscores on the NNNS exam varied from established baseline scores for postmenstrual age. Children who required neurosurgical intervention had higher ventricle/brain ratios and worse NNNS habituation scores. Ventricle sizes were modestly correlated with motor abnormalities (0.24-0.59); larger anterior horn width correlated with nonoptimal reflexes, hypertonicity and hypotonicity. Ventricle sizes were modestly correlated with cognitive scores (-0.44 to 0.27); larger ventricular index correlated with worse attention. Periventricular hemorrhagic infarction correlated with worse habituation. Conclusion: For this cohort of preterm infants with IVH, surgical intervention for posthemorrhagic hydrocephalus correlated with both larger degrees of ventriculomegaly and worse NNNS exams. Findings on both HUS and MRI correlated with motor and cognitive abnormalities on neonatal neurobehavioral exam, suggesting that larger neonatal ventricle sizes and white matter injury have detectable correlates on exam. The NNNS exam provides important additional information when assessing posthemorrhagic ventricular dilation and hydrocephalus of prematurity.

Early Preterm Birth Across Generations Among Whites and African-Americans: A Population-Based Study.

Objectives To determine the extent to which non-Latina White and African-American mother's gestational age is associated with extremely early (<30 weeks), modestly early (30-33 weeks), and late (34-36 weeks) infant preterm birth (PTB) rates. Methods Race-specific stratified and multivariable logistic regression analyses were performed on the Illinois Transgenerational Birth File of non-Latino White and African-American infants (born 1989-1991) and their mothers (born 1956-1976). Results White mothers (n = 184) born at <30 weeks had a greater extremely early infant PTB rate than White mothers (n = 131,980) born at term: 1.6 versus 0.5%, respectively; RR = 3.6 (1.2, 11.0). African-American mothers (n = 269) born at <30 weeks had a greater extremely early infant PTB rate than African-American mothers (n = 34,885) born at term: 4.1 versus 2.1%, respectively; RR = 2.0 (1.1, 3.6). In logistic regression models the adjusted (controlling for maternal age, education, parity, prenatal care, marital status, and cigarette smoking) OR of extremely early PTB for White and African-American mothers born <30 (compared to ≥37) weeks equaled 4.0 (1.2, 12.6) and 2.3 (1.2, 4.3), respectively. The adjusted OR of modestly early PTB for White and African-American mothers born 30-33 (compared to ≥37) weeks equaled 1.6 (1.0, 2.5) and 1.3 (0.9, 1.7), respectively. The adjusted OR of late PTB for White and African-American mothers born 34-36 (compared to ≥37) weeks equaled 1.2 (1.0, 1.3) and 1.1 (1.0, 1.2), respectively. Conclusions A generational association of extremely early, but not modestly early or late, PTB exists among non-Latino Whites and African-Americans.