STUDY OBJECTIVES Children with obstructive sleep apnea syndrome (OSAS) often experience periods of hypercapnia during sleep, a potent stimulator of cerebral blood flow (CBF). Considering this hypercapnia exposure during sleep, it is possible that children with OSAS have abnormal CBF responses to hypercapnia even during wakefulness. Therefore, we hypothesized that children with OSAS have blunted...

neonates with respiratory distress syndrome (rds), who are treated according to insure protocol; require arterial blood gas (abg) analysis to decide on appropriate management. we conducted this study to investigate the validity of pulse oximetry instead of frequent abg analysis in the evaluation of these patients. from a total of 193 blood samples obtained from 30 neonates <1500 grams with rds,...

Permissive hypercapnia, achieved using low tidal volume ventilation, has been an effective protective strategy in patients with acute respiratory distress syndrome. To date, no such protective effect has been demonstrated for the chronic neonatal lung injury, bronchopulmonary dysplasia. The objective of our study was to determine whether evolving chronic neonatal lung injury, using a rat model,...

The "calibrated fMRI" technique requires a hypercapnia calibration experiment in order to estimate the factor "M". It is desirable to be able to obtain the M value without the need of a gas challenge calibration. According to the analytical expression of M, it is a function of several baseline physiologic parameters, such as baseline venous oxygenation and CBF, both of which have recently been ...

BACKGROUND/AIM It is widely accepted that hypercapnia results in increased retinal, choroidal, and retrobulbar blood flow. Reports of a visual response to hypercapnia appear mixed, with normal subjects exhibiting reduced temporal contrast sensitivity in some studies, while glaucoma patients demonstrate mid-peripheral visual field improvements in others. This suggests that under hypercapnic cond...

We have determined the influence of 0.1 minimum alveolar concentration (MAC) of sevoflurane on ventilation, the acute ventilatory response to a step change in end-tidal carbon dioxide and the ventilatory response to sustained hypercapnia in 10 healthy adult volunteers. Subjects undertook a preliminary 10-min period of breathing air without sevoflurane to determine their normal ventilation and n...

TO THE EDITOR: The question raised by Wang et al. (5) in their recent Viewpoint is important inasmuch as apneic events in obstructive sleep apnea (OSA) are associated with both hypoxia and hypercapnia. Given the cerebrovasculature is more sensitive to hypercapnia than hypoxia (2) it is surprising, as Wang et al. (5) indicate, that the impact of OSA-related hypoxemia on neurocognitive consequenc...

OBJECTIVE Hypoxia has been postulated as a key mechanism for neurocognitive impairment in sleep-disordered breathing. However, the effect of hypoxia on the electroencephalogram (EEG) is not clear. METHODS We examined quantitative EEG recordings from 20 normal volunteers under three 5-min ventilatory control protocols: progressive hypercapnia with iso-hyperoxia (pO2=150mmHg) (Protocol 1), prog...

RATIONALE Little is known about the respiratory-related discharge properties of motor units driving any of the eight muscles that control the movement, shape, and stiffness of the mammalian tongue. OBJECTIVES To characterize the respiratory-related discharge of genioglossus motor units as synaptic drive to the hypoglossal motoneuron pool is increased with hypercapnia. MEASUREMENTS We record...

BackgroundA sufficient supply of oxygen is crucial to avoid hypoxic cardiac arrest and brain damage within 30 min in completely-buried avalanche victims. Snow density influences levels hypoxia hypercapnia. The goal this study was investigate the effects hypercapnia on cerebral oxygenation (ScO2) humans breathing into an artificial air pocket.MethodsEach subject breathed a closed system (air-tig...