Background: Hypercarbia increases cerebral blood flow secondary to cerebral vasodilatation, while hypocarbia can lead to vasoconstriction with a subsequent decrease in cerebral blood flow. The aim of this study was to examine CO2 cerebral vasoreactivity in a cohort of premature infants and to identify factors which influence this reactivity. Methods: We prospectively studied a cohort of hemodynamically stable premature infants [birth weight (BW) <1500 g and gestational age (GA) >= 34 weeks]. Subjects underwent two studies, one in the first 72 h and the second after 1 week of life. Infants were continuously monitored via a physiology station that included transcutaneous CO2 (tcPCO(2)) monitor, near-infrared spectroscopy (NIRS), arterial pulse oximetry and heart rate. The total hemoglobin (Hb-T) signal of NIRS was used as an indicator of cerebral blood volume (CBV). Correlation between tcPCO(2) and Hb-T was performed in each 1-h period using Pearson's correlation. Factors affecting the CO2 cerebrovascular reactivity were examined using bivariate and linear regression analyses. Results: A total of 3847 1-h epochs were obtained from 140 studies of 72 premature infants. tcPCO(2) correlated positively with Hb-T in 42% of epochs. In regression analysis, factors associated with increased percentage of positive correlation epochs were male sex and younger postmenstrual age (PMA; beta = 0.176, 0.169 and P-value = 0.036, 0.047 respectively). Factors associated with increased strength of positive correlation were mechanical ventilation and increased average tcPCO 2 (beta = 0.198, 0.220 and P-value = 0.024, 0.011 respectively). Conclusion: Increased prematurity, male sex, mechanical ventilation and hypercarbia are associated with stronger PCO2 cerebrovascular reactivity in premature infants. This association may explain their role in the pathogenesis of brain injury.

Objectives The ability of the premature brain to extract and use oxygen has not been studied adequately. This study aimed to determine factors that influence fractional tissue oxygen extraction (FTOE) of the brain in premature infants using near-infrared spectroscopy (NIRS) and pulse oximetry.Study Design We prospectively studied FTOE in very low birth weight (BW) infants (< 1,500 g and <= 34 weeks' gestation). Factors affecting FTOE and its variability were examined using bivariate and linear regression models. FTOE variability was measured on two scales: short scales (3-20 seconds) and long scales (20-150 seconds).Results We examined 147 simultaneous NIRS and pulse oximetry recordings that were collected from 72 premature infants (gestational age [GA] = 28 weeks and BW = 1,036 g). In regression models, average FTOE correlated negatively with hemoglobin (Hb) and increased significantly in patients with severe intraventricular hemorrhage/periventricular leukomalacia. Both FTOE short-and long-scale variabilities correlated negatively with GA and positively with postnatal age (PNA). Moreover, FTOE long-scale variability was significantly reduced in infants supported with invasive ventilation.Conclusions In premature infants, cerebral oxygen extraction increased with reduced Hb and severe brain injury. Variability in oxygen extraction showed differential changes with GA and PNAs and was affected by invasive ventilation.

Abstract Objectives: Late preterm infants are the fastest growing segment of the premature infant population in the United States. However, it is not known if demographic and clinical factors can impact the length of hospital stay (LOS) in this population. The objectives of this study are to determine the following: (a) factors associated with a LOS > 3 d and (b) whether there is any difference in risks between infants born at 33–34 versus 35–36 weeks. Methods: Utilizing the Nationwide Inpatient Sample Database, a de-identified dataset produced by the Healthcare Cost and Utilization Project, analysis of 81 913 infants born at 33–36 weeks from 2007 to 2008 was conducted. LOS outcome was defined as ≤3 and >3 d. Bivariable and multivariable logistic regression was used to evaluate predictors of LOS among this population. Results: Only 42.7% of infants were discharged home within three days. Factors associated with a LOS > 3 d included gestational age of <35 weeks (RR = 1.63; CI: 1.58–1.68), birth weight of < 2500 g (RR = 1.36; CI: 1.33–1.39), male sex (RR = 1.06; CI: 1.05–1.07), delivery via C-section (RR = 1.46; CI: 1.41–1.51) and multiple gestation (RR = 1.08; 95% CI: 1.06–1.09). Other significant factors included race, birth region, primary insurance payer and clinical complications. In the adjusted interaction model, these variables have more impact on longer LOS in the 35–36 weeks group (p < 0.0001). Conclusion: Birth region in addition to gestational age, birth weight, gender, mode of delivery, multiple gestation and primary insurance payer affect LOS in late preterm infants. These variables are more critical for the 35–36 week population.

We examined the relationship between the use of nasal continuous positive airway pressure (CPAP) and nasal colonization among low-birth-weight (LBW) infants. We prospectively cultured the nares of LBW infants on admission and weekly until hospital discharge. The modality of respiratory support during each culture was recorded. Bivariate and multivariate analyses were conducted to test the relationship between CPAP and nasal colonization. Analyses were repeated after stratifying infants into three birth-weight categories: 1500 to 2499 g, 1000 to 1499 g, and < 1000 g. In total, 766 nasal cultures were obtained from 167 infants. Nasal colonization with gram-negative bacilli was increased with the use of CPAP in all birth-weight categories (p < 0.05) and with vaginal delivery in infants weighing < 1000 g and 1500 to 2499 g (p = 0.04 and p = 0.02, respectively). Nasal colonization with any potential pathogen increased with the use of CPAP in all birth-weight categories (p < 0.001), with the presence of chorioamnionitis in infants < 1000 g (p = 0.055) and at younger gestational age in infants 1000 to 1499 g (p = 0.0026). Caucasian infants 1500 to 2499 g had less colonization than infants of other races (p = 0.01). Nasal CPAP is associated with increased colonization with gram-negative bacilli.

In January 2007, an outbreak of Rift Valley fever (RVF) was detected among humans in northern Tanzania districts. By the end of the outbreak in June, 2007, 511 suspect RVF cases had been recorded from 10 of the 21 regions of Tanzania, with laboratory confirmation of 186 cases and another 123 probable cases. All confirmed RVF cases were located in the north-central and southern regions of the country, with an eventual fatality rate of 28.2% (N = 144). All suspected cases had fever; 89% had encephalopathy, 10% hemorrhage, and 3% retinopathy. A total of 169 (55%) of the 309 confirmed or probable cases were also positive for malaria as detected by peripheral blood smear. In a cohort of 20 RVF cases with known outcome that were also positive for human immunodeficiency virus, 15 (75%) died. Contact with sick animals and animal products, including blood, meat, and milk, were identified as major risk factors of acquiring RVF.

OBJECTIVE:To examine risk factors associated with chorioamnionitis. STUDY DESIGN:We conducted a retrospective cohort study using data on women who delivered prematurely (< 37 weeks of gestation) over a 12-year period. Eleven potential risk factors were identified. Subjects were stratified according to their blood type into 2 groups: group 1, subjects with anti-B antibodies (blood types A and O), and group 2, subjects without anti-B antibodies (blood types B and AB). Univariate, bivariate, and logistic regression analyses were done to examine risk factors for chorioamnionitis while controlling for confounders. RESULTS:The study included 2879 subjects, 96 of whom (3.3%) were diagnosed with chorioamnionitis. Chorioamnionitis increased significantly with alcohol use (adjusted odds ratio [AOR] = 4.7), prolonged rupture of membranes (ROM) (AOR = 4.16), anemia (AOR = 2.17), and group 1 status (AOR = 1.88). Advanced maternal age was protective of chorioamnionitis (AOR = 0.96). CONCLUSION:Alcohol consumption during pregnancy, prolonged ROM, anemia, and blood types A and O are associated with increased risk for chorioamnionitis; advanced maternal age, with decreased risk. Further studies are needed to determine the efficacy of early prenatal care in the control of anemia and to examine its affect on the incidence of chorioamnionitis.