Amphibians exhibit cardiorespiratory responses to hypoxia and, although several oxygen-sensitive chemoreceptor sites have been identified, the specific oxygen stimulus that triggers these responses remains controversial. This study investigates whether the cardiovascular response to oxygen shortage correlates with decreased oxygen partial pressure of arterial blood (Pa(O(2))) or reduced oxygen ...

Alveolar partial pressure of carbon dioxide (PACO2) and alveolar partial pressure of oxygen (PAO2) oscillate at the frequency of respiration and the oscillations persist into the arterial blood as oscillations of arterial partial pressure of carbon dioxide (PaCO2) and arterial partial pressure of oxygen (PaO2). Arterial chemoreceptors respond quickly enough to changes in PaCO2 and PaO2 for the ...

Because cardiovascular disorders and stroke may induce Cheyne-Stokes respiration, our purpose was to study the interaction among cerebral activity, cerebral circulation, blood pressure, and blood gases during Cheyne-Stokes respiration. Ten patients with heart failure or a previous stroke were investigated during Cheyne-Stokes respiration with recordings of daytime polysomnography, cerebral bloo...

BACKGROUND The effect of intranasal oxygen and/or early reversal of xylazine with atipamezole on arterial oxygenation in free-ranging moose (Alces alces) immobilized with etorphine-acepromazine-xylazine with a cross-sectional clinical study on 33 adult moose was evaluated. RESULTS Before treatment the mean±SD (range) partial pressure of arterial oxygen (PaO2) was 62±17 (26-99) mmHg. Twenty-si...

Myocardial oxygen consumption is increased by arterial stiffening. It is not known precisely how. This study aimed to evaluate the role of the incident and reflected pressure wave in raising myocardial oxygen demand. Central (aortic) pressure waveforms were generated from radial waveforms using a generalized transfer function in 1628 cardiology outpatients (1038 males and 590 females). Aortic w...

Cardiorespiratory values were measured in ten patients with severe respiratory failure on volume controlled and pressure controlled ventilation. Tidal volume, respirator rate, PEEP, auto-PEEP, inspiratory:expiratory ratio (1:2) and FIo2 were maintained at the same value for both ventilatory modalities. Changing from VCV to PCV was associated with significant improvements in PaO2, oxygen deliver...

Effects of Blood Gases on the PressureFlow Relationships in Canine Cerebral Circulation • The effects of the arterial oxygen saturation and carbon dioxide pressure on the pressure-flow relationships in cerebral circulation were studied in 22 dogs. The cerebral blood flow was observed with stepwise lowering of the systemic arterial blood pressure by controlled bleeding in normoxic normocapnic, n...

Copyright © 2007 Massachusetts Medical Society. A 55-year-old man who is 178 cm tall and weighs 95 kg is hospitalized with community-acquired pneumonia and progressively severe dyspnea. His arterial oxygen saturation while breathing 100% oxygen through a face mask is 76%; a chest radiograph shows diffuse alveolar infiltrates with air bronchograms. He is intubated and receives mechanical ventila...

Eight patients with a diagnosis of atherosclerotic heart disease and a history of typical angina pectoris, uncomplicated by cardiac dilatation or heart failure, were studied by means of standardized, symptom-limited treadmill exercise test. Repeatability of such testing was determined during two control tests 1-1.5 hours apart. From two to six days later, the same patients performed two treadmi...