Journal of applied physiology
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Airway dilation is one of the many autonomic responses to exercise. Two neural mechanisms are believed to evoke these responses: central command and the muscle reflex. Previously, we found that activation of central command, evoked by electrical and chemical stimulation of the mesencephalic locomotor region, constricted the airways rather than dilated them. ⋯ We found that activation of the hypothalamic locomotor region by electrical and chemical stimuli evoked fictive locomotion and, for the most part, airway constriction. Fictive locomotion also occurred spontaneously, and this too, for the most part, was accompanied by airway constriction. We conclude that central command plays a minor role in the airway dilator response to exercise.
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Randomized Controlled Trial Clinical Trial
Apnea and periodic breathing in bed-sharing and solitary sleeping infants.
Mother-infant bed sharing, compared with the solitary sleeping condition, has recently been associated with several physiological and behavioral effects. Because the physiological effects of bed sharing may also include respiratory changes, we compared the incidence of central and obstructive apneas and periodic breathing in bed-sharing and solitary sleeping infants. Twenty routinely bed-sharing mother-infant pairs and fifteen routinely solitary sleeping pairs slept for 3 nights in a sleep laboratory. ⋯ In both groups, there was a significantly higher frequency of periodic breathing events on the bed-sharing night than on the solitary night. These findings demonstrate that the bed-sharing environment can have a significant impact on respiratory control in the infant. Evidence is also presented to suggest that routine bed sharing may result in subtle neurophysiological and/or developmental differences in infants.
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Clinical Trial
High-frequency oscillatory ventilation in neonatal RDS: initial volume optimization and respiratory mechanics.
To determine whether initial lung volume optimization influences respiratory mechanics, which could indicate the achievement of optimal volume, we studied 17 premature infants with respiratory distress syndrome (RDS) assisted by high-frequency oscillatory ventilation. The continuous distending pressure (CDP) was increased stepwise from 6-8 cmH2O up to optimal CDP (OCDP), i.e., that allowing good oxygenation with the lowest inspired O2 fraction. Respiratory system compliance (Crs) and resistance were concomitantly measured. ⋯ We conclude that there is a marked dissociation between oxygenation improvement and Crs profile during the initial phase of lung recruitment by early high-frequency oscillatory ventilation in infants with RDS. Thus optimal lung volume cannot be defined by serial Crs measurement. At the most, low initial Crs suggests that higher CDP will be needed.