HYPOTHESIS Central venous blood gas (VBG) measurements of pH, PCO2, and base excess can be substituted for the same values obtained from an arterial blood gas (ABG) analysis in mechanically ventilated trauma patients, obviating the need for arterial puncture. DESIGN AND SETTING Prospective comparison of 99 sets of VBGs and ABGs at a level 1 academic trauma center. PATIENTS A consecutive sam...

The growing field of ocean acidification research is concerned with the investigation of organism responses to increasing pCO2 values. One important approach in this context is culture work using seawater with adjusted CO2 levels. As aqueous pCO2 is difficult to measure directly in smallscale experiments, it is generally calculated from two other measured parameters of the carbonate system (oft...

PURPOSE To test the potential participation of pericytes in the regulation of capillary blood flow according to metabolic needs. METHODS The authors measured the change in extracellular pH (pHo), intracellular pH (pHi), and contractile tone of cultured bovine retinal pericytes when the ambient carbon dioxide (CO2) level was changed. RESULTS Raising the partial pressure of CO2 (PCO2) from 5%...

To ascertain whether and to what extent the reduced ventilatory response to a hypercapnic stimulus in chronic obstructive pulmonary disease (COPD) patients depends on a blunted chemoresponsiveness of central origin or to mechanical impairment, we studied two groups of COPD patients without (group A) and with (group B) chronic hypercapnia, but with similar degrees of airway obstruction and hyper...

We measured the PCO2 apneic threshold in preterm and term infants. We hypothesized that, compared with adult subjects, the PCO2 apneic threshold in neonates is very close to the eupneic PCO2, likely facilitating the appearance of periodic breathing and apnea. In contrast with adults, who need to be artificially hyperventilated to switch from regular to periodic breathing, neonates do this spont...

Currently, atmospheric CO2 levels fluctuate around 390 ppm and continue to rise at an accelerating rate (Caldeira and Wickett 2003, 2005); projected scenarios indicate that levels will approach 450–600 ppm by 2050 and 750– 1,000 ppm by the end of the twenty-first century (IPCC 2007; gattuso and lavigne 2009). The resultant increase in dissolved seawater CO2 is expected to reduce surface ocean p...

Predicting the effects of anthropogenic CO2 emissions on coastal ecosystems requires an understanding of the responses of algae, since these are a vital functional component of shallow-water habitats. We investigated microphytobenthic assemblages on rock and sandy habitats along a shallow subtidal pCO2 gradient near volcanic seeps in the Mediterranean Sea. Field studies of natural pCO2 gradient...

Marine organisms are exposed to increasingly acidic oceans, as a result of equilibration of surface ocean water with rising atmospheric CO2 concentrations. In this study, we examined the physiological response of Mytilus edulis from the Baltic Sea, grown for 2 months at 4 seawater pCO2 levels (39, 113, 243 and 405 Pa/385, 1,120, 2,400 and 4,000 latm). Shell and somatic growth, calcification, ox...

A study was designed to investigate the possibility that changes in ventral medullary extracellular fluid carbon dioxide tension (PCO2) and hydrogen ion (H+) concentration mediate the ventilatory stimulation induced by systemic administration of aminophylline. Six cats with peripheral chemodenervation (bilateral carotid sinus nerve and vagal neurotomy) were studied while anaesthetised with chlo...