Ruben E. Alvaro

Effects of central apnea on cerebral blood flow velocity in healthy term infants.

We evaluated a new method of monitoring cerebral blood flow velocity (CBFV) and described changes in CBFV in relation to central apnea in 17 healthy term infants. The area under the velocity curve during apnea did not change, whereas area under the velocity curve per the waveform showed a significant difference, suggesting that stability is maintained through an increase in CBFV with each heartbeat. The maintenance of cerebral hemodynamics during isolated central apnea supports the assumption that these episodes are benign.

Severe Neurodevelopmental Impairment in Neonates Born Preterm: Impact of Varying Definitions in a Canadian Cohort

Objective To assess the impact of variations in the definition of severe neurodevelopmental impairment (NDI) on the incidence of severe NDI and the association with risk factors using the Canadian Neonatal Follow‐Up Network cohort. Study design Literature review of severe NDI definitions and application of these definitions were performed in this database cohort study. Infants born at 23‐28 completed weeks of gestation between 2009 and 2011 (n = 2187) admitted to a Canadian Neonatal Network neonatal intensive care unit and assessed at 21 months corrected age were included. The incidence of severe NDI, aORs, and 95% CIs were calculated to express the relationship between risk factors and severe NDI using the definitions with the highest and the lowest incidence rates of severe NDI. Results The incidence of severe NDI ranged from 3.5% to 14.9% (highest vs lowest rate ratio 4.29; 95% CI 3.37‐5.47). The associations between risk factors and severe NDI varied depending on the definition used. Maternal ethnicity, employment status, antenatal corticosteroid treatment, and gestational age were not associated consistently with severe NDI. Although maternal substance use, sex, score of neonatal acute physiology >20, late‐onset sepsis, bronchopulmonary dysplasia, and brain injury were consistently associated with severe NDI irrespective of definition, the strength of the associations varied. Conclusions The definition of severe NDI significantly influences the incidence and the associations between risk factors and severe NDI. A standardized definition would facilitate site comparisons and scientific communication.

Effects of Inhaled Nitric Oxide (INO) on Ventilation in Healthy Pretern Infants † 1598

Inhaled Nitric Oxide (INO) improves oxygenation and decreases mortality in newborn infants with persistent pulmonary hypertension. However, the effect of INO on ventilation in preterm infants with healthy lungs is unknown. We hypothesize that INO by preferentially vasodilating capillaries in well ventilated areas would decrease dead space and improve gas exchange in healthy preterm infants. To test this hypothesis, we studied 6 healthy preterm infants[BW 1100±237 g (Mean±SEM); SW 1780±140 g; GA 28±1 wk; PNA 54±14 d] during quiet and REM sleep. A flow-through system and Beckman analyzers were used to measure ventilation and alveolar gases. After a control period in 21% O2, infants inhaled 5 ppm of NO for one hour. In quiet sleep, minute ventilation decreased from 0.305±0.011 (control), to 0.260±0.008 l/min/kg (INO; p<0.001). In REM sleep, it decreased from 0.299±0.007 (control), to 254±0.011 l/min/kg (INO; p<0.001). These changes in ventilation were primarily related to a decrease in frequency during quiet sleep [45±3 breaths/minute (control) vs 36±1 (INO); p<0.01] and to a decrease in tidal volume during REM sleep [7.1±0.3 ml/kg (control) vs 6.6±0.3 (INO); p<0.05]. No significant differences were observed in the number and the density of apneas per hour in any sleep state. Oxygenation, as measured by O2 saturation and TcPO2, did not change significantly during INO in any sleep state. Alveolar PO2 was 100±2 Torr (quiet) and 97±2 (REM) during control and 97±3 Torr (quiet) and 100±4 (REM) during INO (both p=NS). Alveolar PCO2 decreased from 33±1 Torr (control) to 32±1 (INO; p=NS) during quiet sleep and from 31±1 Torr(control), to 29±1 (INO; p<0.05) during REM sleep. These findings suggest that in healthy preterm infants INO makes ventilation more effective; this is indicated by a decrease in minute ventilation during quiet and REM sleep without significant changes in oxygenation and with a slight decrease in alveolar PCO2. We speculate that the more effective ventilation observed during INO is related to capillary recruitment in poorly perfused ventilated alveolar units with a consequent decrease in dead space.

Charaterization of Pacemaker Cells Uniquely Responsive to CO 2 : Effects of Neuromediators and a Placental Extract ♦ 1731

Charaterization of Pacemaker Cells Uniquely Responsive to CO 2 : Effects of Neuromediators and a Placental Extract ♦ 1731

A COMPARISON OF THE VENTILATORY RESPONSE TO HYPOXIA IN NEONATES AND ADULT SUBJECTS DURING SLEEP. † 2315

A COMPARISON OF THE VENTILATORY RESPONSE TO HYPOXIA IN NEONATES AND ADULT SUBJECTS DURING SLEEP. † 2315