Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Randomized Controlled Trial
Contribution of the nasal passage to face mask ventilation: a prospective blinded randomized crossover trial.
Previous studies have shown that the nasal passage plays an important role in manual face mask ventilation, but this has yet to be quantitatively assessed. We conducted a prospective randomized crossover clinical trial to compare the change in pressure-controlled face mask tidal volume with and without nasal airway occlusion. ⋯ Nasal passage obstruction considerably reduces tidal volume achieved during face mask ventilation. In some patients, it may be advantageous to relieve nasal airway obstruction for effective face mask ventilation.
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External compression of the jugular veins is an effective method to increase intracranial blood volume and brain stiffness in rats and healthy volunteers. It has been reported that, on assuming an upright posture, cerebral venous drainage is distributed away from the internal jugular veins (IJVs) to the cervical venous plexus, causing complete collapse of the IJV. If so, it is not clear why external IJV compression would increase intracranial blood volume, but the latter is frequently observed in neurosurgery in the sitting position. The aim of this study was to observe the effect of external IJV compression and the Valsalva maneuver on the change in IJV cross-sectional area and IJV flow in volunteers in the upright posture. ⋯ Compression of the internal jugular veins or an increase in intrathoracic pressure does not reduce venous drainage but actually may increase intracranial venous volume.