The hypoxic test in preterm neonates reinvestigated.

AIM: We currently lack a suitable gold-standard method for implementation on modern equipment to assess peripheral chemoreceptor sensitivity. The aim of the present study was to develop an accurate and reproducible method for assessing peripheral chemoreceptors sensitivity in sleeping preterm neonates. METHODS: A poïkilocapnic hypoxic test was performed twice during rapid eye movement sleep (REM sleep) and non-rapid eye movement sleep (nonREM sleep). The infant breathed hypoxic gas (15% O2 ) for 60 s. The ventilatory response to hypoxia was assessed by comparing minute ventilation during the control period (21% O2 ) with successive 4-cycles sequences during hypoxia. We detected the first statistically significant increase in minute ventilation and recorded the corresponding response time. RESULTS: During normoxia, minute ventilation was higher during REM sleep than in nonREM sleep (428.1 mL · min-1 · kg-1 [307.7-633.6]; 388.8 mL · min-1 · kg-1 [264.7-608.0], respectively; P = 0.001). After hypoxia, minute ventilation increased in both REM and nonREM sleep. The response was significantly higher in REM than in nonREM (25.3% [10.8-80.0] and 16.8% [7.5-33.2], respectively; P = 0.005). The intraclass correlation coefficients for all respiratory parameters were above 0.90. CONCLUSION: We have developed a highly reliable method for assessing peripheral chemoreceptors sensitivity at the response time to hypoxia. In the future, researchers could use this method to assess the involvement of peripheral chemoreceptors in infants who experience chronic hypoxia (e.g. in bronchopulmonary dysplasia and recurrent apnea).

Isolated hypospadias: The impact of prenatal exposure to pesticides, as determined by meconium analysis.

Although endocrine-disrupting chemicals (EDCs, including pesticides) are thought to increase the risk of hypospadias, no compounds have been formally identified in this context. Human studies may now be possible via the assessment of meconium as a marker of chronic prenatal exposure. The objective of the present study was to determine whether or not prenatal exposure to pesticides (as detected in meconium) constitutes a risk factor for isolated hypospadias. In a case-control study performed between 2011 and 2014 in northern France, male newborns with isolated hypospadias (n = 25) were matched at birth with controls (n = 58). Newborns with obvious genetic or hormonal anomalies, undescended testis, micropenis, a congenital syndrome or a family history of hypospadias were not included. Neonatal and parental data were collected. Foetal exposure was assessed by determining the meconium concentrations of the pesticides or metabolites (organophosphates, carbamates, phenylurea, and phenoxyherbicides) most commonly used in the region. Risk factors were assessed in a multivariate analysis. The pesticides most commonly detected in meconium were organophosphates (in up to 98.6% of samples, depending on the substance) and phenylurea (>85.5%). A multivariate analysis revealed an association between isolated hypospadias and the presence in meconium of the phenylurea herbicide isoproturon and of the phenoxyherbicide 2-methyl-4-chlorophenoxyacetic acid (odds ratio [95% confidence interval]: 5.94 [1.03-34.11] and 4.75 [1.20-18.76]) respectively). We conclude that prenatal exposure to these two herbicides (as assessed by meconium analysis) was correlated with the occurrence of isolated hypospadias. The results of our case-control study (i) suggest that prenatal exposure to pesticides interferes with the development of the male genitalia, and (ii) emphasize the importance of preventing pregnant women from being exposed to EDCs in general and pesticides in particular.