ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Over a century ago, Stokes wrote on the oxidation and reduction of “the colouring substance of the blood.” The mechanisms that govern the binding of oxygen to hemoglobin have been defined in even greater detail and higher orders of accuracy, even to the ends of the oxyhemoglobin dissociation curve. The Bohr effect has ceased to be a reduction in the affinity of hemoglobin for oxygen due to an increasing hydrogen ion concentration and according to a mere logarithmic equilibration constant. The constant has become a variable, subject to the interactions of temperature, carbon dioxide, organic phosphate, and ionic concentrations. This interdependence of so many variables has rendered the once inaccurate, but precise prediction of the effect of the reactants on oxyhemoglobin dissociation into a technological juggling act, well beyond the means of the average physician managing the treatment of a sick patient.

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The oxygen delivery system consists of multiple components balanced to provide optimal oxygen supply to all tissues and arranged such that an abnormality in one component is compensated by adjustments in others. Analysis of pertinent data indicates that leftward shifts of the oxygen dissociation curve (ODC) in normal animals and persons elicit adaptive changes in other components which sustain normal oxygen supply. By contrast, several recent studies indicate that leftward ODC shifts, when occurring in combination with other abnormalities of oxygen delivery, produce or aggravate hypoxia. These data suggest that the brain and heart are the organs particularly at risk. It is concluded that leftward ODC shifts, due to massive transfusion of stored blood and to hyperventilation of unconscious patients, are most likely to be hazardous in the presence of poor perfusion, coronary artery disease, or cerebrovascular disease.

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Cardiovascular responses have been studied in baboons, after total exchange transfusion with hemoglobin solutions having various P50values. At the end of the exchange transfusion, the hematocrit was 1.5%, the mean hemoglobin concentration was 4.4 g/dl, and the P50varied between 12 and 26 mm Hg. Cardiac output did not change during the study, although heart rate increased, and stroke volume and MAP decreased. Hemoglobin concentration, per se, does not appear to be the critical stimulus for an increase in cardiac output with hemoglobin solution. In addition, the position of the hemoglobin-oxygen dissociation curve does not appear to influence these hemodynamic responses. The physiological response to anemia in the presence of hemoglobin solution appears different from that observed in the absence of plasma O2carriers.

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The Unicam Spectrophotometer, the IL 282 CO-Oximeter, and the Hemoscan were used to measure the in vitro P50using 1, 20–45, and 50% hematocrit values of red blood cells suspended in autologous plasma or phosphate buffered saline at pH of 6.7–7.7. The relation between pH and P50was a linear correlation for washed red blood cells by all three methods whereas the relation between pH and P50was a log correlation for red blood cells in plasma.Multiple units of red blood cells with low 2,3 diphosphoglycerate (2,3 DPG) and increased affinity for oxygen, with normal 2,3 DPG and normal affinity for oxygen, and above normal 2,3 DPG and decreased affinity for oxygen, were frozen in 10 ml aliquots with 40% w/v glycerol and maintained at −80°C. One tube of each level of 2,3 DPG was thawed, washed, and suspended in buffer daily to yield P50values of 17.5 ± 0.67, 29.7 ± 0.92, or 41.2 ± 0.72 torr at pH 7.2 in order to have a control of both instrumentation and personnel.

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The accurate determination of the oxygen equilibrium curve (OEC) of whole blood or red cell suspensions requires special considerations to avoid the secondary effects due to lactate formation, removal of carbon dioxide, use of anticoagulants, etc. An automated apparatus has been constructed that can record the whole OEC of red cells within 20 min. The instrument also can be used to record the OEC of hemolysate. The pH, temperature, and PO2are monitored constantly during the measurement. Using this instrument, the effects of pH, temperature, carbon dioxide, anticoagulants, and buffers on the OEC of normal fresh blood have been investigated. The OEC of normal blood, blood containing abnormal hemoglobin, or enzyme, were determined. The results were compared with those obtained using commercial OEC apparatuses.

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1979

数据来源: OVID