Cherry AD, Forkner IF, Frederick HJ, Natoli MJ, Schinazi EA, Longphre JP, Conard JL, White WD, Freiberger JJ, Stolp BW, Pollock NW, Doar PO, Boso AE, Alford EL, Walker AJ, Ma AC, Rhodes MA, Moon RE. Predictors of increased PaCO2 during immersed prone exercise at 4.7 ATA. J Appl Physiol 106: 316–325, 2009. First published September 11, 2008; doi:10.1152/japplphysiol.00885.2007.— During diving, a...

INTRODUCTION Our aims in this study were to report changes in the ratio of alveolar dead space to tidal volume (VDalv/VT) in the prone position (PP) and to test whether changes in partial pressure of arterial CO2 (PaCO2) may be more relevant than changes in the ratio of partial pressure of arterial O2 to fraction of inspired O2 (PaO2/FiO2) in defining the respiratory response to PP. We also aim...

Cardiac arrest (CA) causes ischaemic brain injury and persistent cerebral hypoperfusion and cerebral hypoxia during the early post-resuscitation period. PaCO2 is the major physiological regulator of cerebral blood flow, is a modifiable component of care and mild hypercapnia may lead to improved neurological outcomes for resuscitated CA survivors. In order to evaluate the potential therapeutic r...

failure with NIV In their recent paper Nickol et al studied the possible mechanisms by which non-invasive ventilation (NIV) improves ventilatory failure in patients with a restrictive defect due to either neuromuscular disease or kyphoscoliosis. They investigated three possible hypotheses for reduction in daytime hypercapnia— namely, increased ventilatory sensitivity to CO2, improved respirator...

Measurements of total and regional cerebral blood flow in paralyzed rats maintained on 70% N2O/30% O2 obtained by a diffusible tracer technique, iodoantipyrine, and by a particle distribution method, microspheres, have been compared. Total CBF values were in good agreement, 0.86 +/- 0.07 ml/g/min (PaCO2 37.3 +/- 1.5, iodoantipyrine method) and 0.88 +/- 0.02 (PaCO2 36.2 +/- 0.8, microsphere meth...

The cerebrovascular response to hypercapnia and hyperventilation was studied in normal and jaundiced baboons by the intracarotid 133Xe injection technique. The baboons with bile duct ligation were found to have decreased CBF at all levels of PaCO2. This difference between normal and jaundiced baboons was 13% at normocapnia rising to 33% with hypercapnia and 37% with hypocapnia. The CBF values a...

One hundred consecutive patients were randomly given hypocarbic (PaCO2 less than 25 torr) or hypercarbic (PaCO2 greater than 60 torr) general anesthesia during carotid endarterectomy to test the effect of the two regimens upon the incidence of postoperative neurological deficit. An indwelling shunt was not used. One patient died, two have permanent neurological deficits and two have temporary n...

In eight patients with pleural effusion arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2), pH, respiratory frequency, and cardiac rhythm and frequency were measured before, during, and after thoracoscopy. Four of the patients had a PaO2 below 70 mm Hg (9.3 kPa) before the procedure. During and after the procedure respiratory frequency increased and PaCO2 fell, indicating hyperventila...

Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decrease...

In this study, the activities of the two external glossal muscles, Genioglossus (Gg) and Styloglossus (Sg), related to respiration were examined through the electromyography (EMG) in dog. During quiet breathing, no phasic respiratory activity were observed in either muscle. With hypercapnic condition induced by closed rebreathing respiratory system, both Sg and Gg showed phasic respiratory acti...