The effects of hypercapnia on enhancement of reduced cerebral perfusion were re-evaluated in areas of ischemia produced by occlusion of the canine middle cerebral artery. Perfusion was measured by 85Kr (beta-ray) and 133Xe (gamma-ray) clearances, fluorescein angiography and diameter measurement of arteries. Between 45 and 55 mm Hg of PaCO2 rCBF measured with both isotopes increased significantl...

Immobilization stress of conscious, normotensive, freely breathing 10-month-old Wistar-Kyoto rats produced an overall decline in regional cerebral blood flow (rCBF), as measured with [14C]iodoantipyrine, except at the frontal lobe. In 14 brain regions, rCBF fell by an average of 14.3% after 5 min of immobilization and by 11.9% after 15 min. Immobilization stress also stimulated hyperventilation...

The aim of the present study was (i) to investigate the effect of inner speech on cerebral hemodynamics and oxygenation, and (ii) to analyze if these changes could be the result of alternations of the arterial carbon dioxide pressure (PaCO2). To this end, in seven adult volunteers, we measured changes of cerebral absolute [O2Hb], [HHb], [tHb] concentrations and tissue oxygen saturation (StO2) (...

Background: Diagnosis of brain death usually requires an arterial carbon dioxide partial pressure (PaCO2) of 60 mmHg during the apnea test, but the increase in PaCO2 is unpredictable. The authors evaluated whether transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring during apnea test can predict that a PaCO2 of 60 mmHg has been reached. Methods: The authors compared PtcCO2 measure...

In 11 normally oxygenated, normotensive mongrel dogs, blood flow and oxidative metabolism of the brain was studied during normocapnia and during respiratory alkalosis and respiratory acidosis. During respiratory alkalosis (mean PaCO2 17.8 mm Hg) CBF decreased significantly from 61.0 to 33.9 ml/100 g/min (44%) while arteriovenous-substrate differences increased and the rates of oxygen and glucos...

TO THE EDITOR: Wood et al. (9) report that end-tidal PCO2 (PETCO2) in young men increases with increased external dead space (DS) at rest and equally so during moderate exercise, such that the slope of the resultant ventilation (V̇E)-metabolic CO2 production (V̇CO2) relationship is potentiated. The authors call this potentiation effect in humans “short-term modulation.” Apart from this change of ...

OBJECTIVE To determine frequency and severity of postanesthetic hypoxemia and hypercarbia in healthy dogs undergoing elective ovariohysterectomy or castration and given butorphanol or hydromorphone for analgesia. DESIGN Prospective trial. ANIMALS 0 healthy dogs weighing > 10 kg (22 lb). PROCEDURE Dogs were anesthestized with acepromazine, glycopyrrolate, thiopental, and isoflurane, and bu...

The effect of locally induced cerebral ischemia on regional cerebral blood flow before and during elevation of Paco2 was measured qualitatively in anesthetized dogs by a thermistor probe technique and a photographic method involving cerebral angiography. The flow response to changes in systemic arterial pressure was also noted in the ischemic zone. Increased Paco2 resulted in increased flow to ...

Sleep disturbance related symptoms are common in patients with long-term oxygen therapy (LTOT). Essentially, there were only few previous reports about the sleep architecture in patients with respiratory disease, such as chronic obstructive pulmonary disease (COPD). This study aims to clarify the objective sleep state and the elements that affect sleep architecture in Chronic Respiratory Failur...

Experiments were performed to measure the apneic threshold for CO2 and its fundamental properties in anesthetized rats under steady-state conditions. Breathing was detected from diaphragmatic electromyogram activity. Mechanical hyperventilation resulted in apnea once arterial PCO2 (PaCO2) had fallen far enough. Apnea was not a reflex response to lung inflation because it did not occur immediate...