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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An Ohmeda Biox 3700 oximeter was evaluated during treatment of 12 patients with respiratory distress. The infants were of 27-33 weeks' gestation and between 2 days and 5 months postnatal age. Blood gases were taken from indwelling arterial catheters and were measured on an ABL 30 blood gas analyser. The study tested the accuracy of the oximeter in detecting hypoxia (PaO2 less than 55 mmHg) and hyperoxia (PaO2 greater than 80 mmHg). Results are based on 175 paired observations. Guidelines are suggested for the use of the pulse oximeter under three conditions. In a newborn infant with acute respiratory distress without direct arterial access, the limits should be set at 85% (lower) and 90% (upper). In an older infant with chronic respiratory distress, the upper limit of use should be 95%. In order to avoid oxygen tensions less than 55 mmHg which would increase the risk of pulmonary vasoconstriction, however, the lower limit should be 87%. Infants with indwelling arterial lines during their first few weeks of treatment should have oxygen tension measurements and simultaneous oxygen saturation readings plotted on a graph at the bedside. The graph should be updated every 48 h to take into account changed levels of 2,3-diphosphoglycerate, haemoglobin F, and carboxyhaemoglobin and the recommended limits should be changed accordingly.
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PMID:Guidelines for the use of pulse oximetry in the non-invasive estimation of oxygen saturation in oxygen-dependent newborn infants. 314 63

Hypoxia is the alleged stimulus for initiation of increase of carbonic anhydrase II (CAII) and 2,3-diphosphoglycerate (2,3-DPG) synthesis of red blood cells from late chick embryos. The PO2-dependent regulation of red cell metabolism is mediated by unknown humoral factors [Million et al., Am. J. Physiol. 261 (Regulatory Integrative Comp. Physiol. 30): R1188-R1196, 1991]. In the present investigation we have analyzed whether interindividual differences in egg size (which result in different surface area-to-mass ratios) affect the timing of initiation of 2,3-DPG and CAII synthesis in late chick embryos. We also investigated the effect of extracellular adenine nucleotides on red cell organic phosphate pattern and O2 affinity to test whether the inhibitory effect of normal or elevated PO2 on 2,3-DPG synthesis and the concomitant increase of ATP (and O2 half-saturation pressure) can be mimicked by these agents. The results show that differences in egg size affect the timing of CAII and 2,3-DPG synthesis, indicating that PO2-dependent regulation of red cell function allows adjustment to the properties of the individual egg. We also found that extracellular ATP, which is rapidly degraded to AMP by red cell ectoenzymes, can alter the red cell phosphate pattern and O2 affinity, i.e., significantly increase red cell ATP, decrease red cell 2,3-DPG and O2 affinity, and thus mimic the effect of normoxia and hyperoxia. These findings suggest that extracellular adenine nucleotides may be involved in the PO2-dependent regulation of embryonic red cell metabolism.
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PMID:Control of red cell function of late chick embryos: role of extracellular ATP/AMP and egg size. 806 66