The Relationships between Arterial Oxygen Flow Rate, Oxygen Binding by Hemoglobin, and Oxygen Utilization after Myocardial Infarction

Abstract

A B S T R A C T The interrelationships of arterial oxygen flow rate index, oxygen binding by hemoglobin, and oxygen consumption have been examined in patients with acute myocardial infarction. Proportional extraction of oxygen increased in close association with decreasing oxygen flow rate, and hence, whole body oxygen consumption was constant over nearly a threefold variation in arterial oxygen flow rate. A reduction in hemoglobin-oxygen affinity at in vivo conditions of pH, PCo2 and temperature also occurred in proportion to the reduction in arterial oxygen flow rate. Therefore, the increased proportional removal of oxygen from arterial blood at low oxygen flow rates, required to maintain oxygen consumption, may have been facilitated by the reduced affinity of hemoglobin for oxygen at in vivo conditions. However, the decrease in affinity did not appear to explain more than 30-40%0 of the increased extraction.Respiratory alkalosis was a frequent occurrence in these patients and 2,3-diphosphoglycerate was positively associated with blood pH as well as with the time-averaged proportion of deoxyhemoglobin in arterial and venous blood.Hemoglobin-oxygen affinity measured at standard conditions and the mixed venous oxygen saturation were equally good indicators of reduced arterial oxygen flow rate in patients without shock. However, Svro2 is more easily measured and is a more useful indicator of reduced oxygen flow rate, since its relationship to oxygen flow appears to be independent of affinity changes and time.

Preservation of canine myocardial high-energy phosphates during low-flow ischemia with modification of hemoglobin–oxygen affinity

“…Increased hemoglobin p50 is reported in patients during angina (7), after acute myocardial infarction (8)(9)(10), with congestive heart failure and cardiogenic shock (12,13,25), as well as in patients with congenital heart disease (26). Higher 2,3-diphosphoglycerate (DPG) levels contribute to the increased p50 in these clinical settings (11) and is typically on the order of ∼2-3 mmHg.…”

“…There are several naturally occurring modifiers of hemoglobin affinity, including 2,3-diphosphoglycerate (DPG), CO 2 , and H + . A rightward shift in the Hb-O 2 dissociation curve is observed in patients with angina, congestive heart failure with shock, and acute myocardial infarction, and is believed to be an adaptive response that increases myocardial oxygen delivery (7)(8)(9)(10)(11)(12)(13). Clofibrate and some other synthetic compounds also modestly alter the affinity of hemogloPreservation of canine myocardial high-energy phosphates during low-flow ischemia with modification of hemoglobin-oxygen affinity bin for oxygen (14)(15)(16)(17)(18) (19,20).…”

Oxygen Demand-Supply Relationship in Peripheral Tissues as a Therapeutic Indicator in Acute Myocardial Infarction with Advanced Heart Failure

“…But even if oxygen delivery decreases, oxygen uptake may be maintained by the fol lowing mechanisms: ( 1 ) the oxygen extraction ratio is accelerated in peripheral tissues [4]; (2) the distribution of regional blood flow is shifted to vital organs that have large oxygen demand [6.7]; (3) the oxygen-hemoglobin dis sociation curve shifts to the right and acceler ates the oxygen release from erythrocytes [8,9]. Under these conditions, the oxygen uptake is independent of the oxygen supply.…”

Sickle β‐thalassemia: Identical twins differing in severity implicate nongenetic factors influencing course

“…Peripheral blood globin-synthetic rates were measured by incubation of whole cells with H-L-leucine (7) and subsequent separation of globin chains by carboxymethylcellulose chromatography in urea (8). Blood gases, carboxy-hemoglobin concentration, oxygen p50, and red cell 2,3-DPG concentration were measured by methods previously described by Lichtman et al (9). Red cell survival was measured by injection of their own red cells labeled with radioactive chromium.…”