The oxygen consumption/oxygen delivery curve in severe preeclampsia: Evidence for a fixed oxygen extraction state

1993 ◽  
Vol 169 (6) ◽  
pp. 1448-1455 ◽  
Author(s):  
Michael A. Belfort ◽  
John Anthony ◽  
George R. Saade ◽  
Nathan Wasserstrum ◽  
Richard Johanson ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
Severe Preeclampsia ◽  
Oxygen Extraction

Effect of Acute Respiratory Acidosis on the Limits of Oxygen Extraction during Hemorrhage

1996 ◽  
Vol 85 (4) ◽  
pp. 817-822 ◽  
Author(s):  
Michael E. Ward
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Content ◽  
Oxygen Delivery ◽  
Tissue Oxygenation ◽  
Respiratory Acidosis ◽  
Oxygen Availability ◽  
Oxygen Extraction ◽  
Oxygen Extraction Ratio ◽  
Critical Oxygen

Background Hypercapnia can impair cells' capacity to maintain energy status anerobically and enhances the risk of hypoxic injury when oxygen availability is reduced. The ability to maintain tissue oxygenation is determined by both bulk blood flow and the efficiency of oxygen extraction. Bulk blood flow is maintained during hypercapnia through increased sympathetic activity. The effect of hypercapnia on oxygen extraction, however, is unknown. This study evaluates the effect of hypercapnia on cells' capacity to adapt to reductions in oxygen availability by increasing oxygen extraction. Methods In three groups of paralyzed, mechanically ventilated dogs that were anesthetized with alpha-chloralose, the concentration of carbon dioxide in the inhaled gas mixture was adjusted to achieve normocapnia, moderate hypercapnia (Paco2 = 72 +/- 3 [SE] mmHg) or severe hypercapnia (Paco2 = 118 +/- 4 [SE] mmHg). Stepwise hemorrhage was induced until each dog's blood pressure was destabilized. At each stage in the hemorrhage protocol, the oxygen delivery, oxygen consumption, and oxygen extraction ratios (ratio of arteriovenous oxygen content difference to arterial oxygen content) were determined. Results At the point of onset of delivery dependence of oxygen consumption, the oxygen delivery rate (critical oxygen delivery) was 7.8 +/- 1.5 (SE) ml.kg-1.min-1 and the oxygen extraction ratio (critical oxygen extraction ratio) was 0.72 +/- 0.04 (SE) in the normocapnic dogs. Moderate hypercapnia had no effect on these parameters. In the severely hypercapnic dogs, the critical values for oxygen delivery and extraction ratios were 12.5 +/- 1.8 (SE) ml.kg-1.min-1 and 0.54 +/- 0.035 (SE), respectively (P < 0.05 for differences from the normocapnic dogs). Conclusions The results identify a previously unrecognized threat to tissue oxygenation and emphasize the importance of ensuring adequate oxygen delivery when adopting mechanical ventilatory strategies that permit respiratory acidosis to develop.

Low oxygen extraction despite high oxygen delivery causes low oxygen consumption in patients with burns recovering slowly from operative hypothermia

Surgery ◽  
1995 ◽  
Vol 118 (1) ◽  
pp. 44-48 ◽  
Author(s):  
T SHIOZAKI ◽  
M OHNISHI ◽  
O TASAKI ◽  
A HIRAIDE ◽  
T SHIMAZU ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
High Oxygen ◽  
Oxygen Extraction ◽  
Low Oxygen

Dependence of oxygen consumption on oxygen delivery in children with hyperdynamic septic shock and how oxygen extraction

1990 ◽  
Vol 18 (12) ◽  
pp. 1316-1319 ◽  
Author(s):  
STEVEN E. LUCKING ◽  
THOMAS M. WILLIAMS ◽  
FRANK C. CHATEN ◽  
RICHARD I. METZ ◽  
JOHN J. MICKELL
Keyword(s):  
Septic Shock ◽  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
Oxygen Extraction ◽  
Hyperdynamic Septic Shock

scholarly journals Cerebral Fractional Oxygen Extraction is Inversely Correlated with Oxygen Delivery in the Sick, Newborn, Preterm Infant

2005 ◽  
Vol 25 (5) ◽  
pp. 545-553 ◽  
Author(s):  
Christopher M Kissack ◽  
Rosaline Garr ◽  
Stephen P Wardle ◽  
A Michael Weindling
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Preterm Infants ◽  
Metabolic Activity ◽  
Negative Correlation ◽  
Oxygen Delivery ◽  
Near Infrared ◽  
Extremely Low Birth Weight ◽  
Oxygen Extraction ◽  
Cerebral Oxygen

Cerebral blood flow (CBF) is known to be low in newborn infants, but this has not been shown to be damaging. The purpose of this study was to investigate the relationships between cerebral haemoglobin flow, blood flow, oxygen delivery, oxygen consumption, venous saturation, and fractional oxygen extraction (OEF) in newborn, preterm infants. Measurements were made by near-infrared spectroscopy in 13 very preterm, extremely low birth weight infants (median gestation 25 weeks) during the first 3 days after birth. There was a negative correlation between cerebral oxygen delivery and OEF ( n=13, r=−0.5, P=0.03), which implies that when there is a reduction in cerebral oxygen delivery in sick preterm infants, increased cerebral oxygen extraction may be responsible for maintaining oxygen availability to the brain. During the first 3 days after birth CBF ( n=13, r=0.7, P=0.01), oxygen delivery ( n=13, r=0.5, P=0.03), and oxygen consumption ( n=13, r=0.7, P=0.004) all increased. This increase in oxygen consumption indicates increased cerebral metabolic activity after birth, which is likely to be a normal adaptation to extrauterine life. The increases in blood flow and oxygen delivery may also be normal adaptations that facilitate this increase in metabolic activity. There was a decrease ( P=0.04) in mean (±s.d.) cerebral OEF between day 1 (0.37±0.10) and day 2 (0.29±0.09), with no change between day 2 and day 3. Taking into account the negative correlation between OEF and oxygen delivery, this decrease in OEF may be because of increased oxygen delivery during this time.

Intestinal and Cerebral Oxygenation during Severe Isovolemic Hemodilution and Subsequent Hyperoxic Ventilation in a Pig Model

2002 ◽  
Vol 97 (3) ◽  
pp. 660-670 ◽  
Author(s):  
Jasper van Bommel ◽  
Adrianus Trouwborst ◽  
Lothar Schwarte ◽  
Martin Siegemund ◽  
Can Ince ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
Oxygen Supply ◽  
Cerebral Oxygenation ◽  
Oxygen Extraction ◽  
Control Group ◽  
Isovolemic Hemodilution ◽  
Systemic Oxygen ◽  
Fraction Of Inspired Oxygen ◽  
Hyperoxic Ventilation

Background During severe isovolemic hemodilution, determination of critical hematocrit levels for the microvascular oxygenation of different organs might provide more insight into the effect of the redistribution of blood flow and oxygen delivery on the oxygenation of different organs. The effect of an increased amount of dissolved oxygen on tissue oxygenation during severely decreased hematocrit levels is not clear. Methods Fifteen anesthetized pigs were randomized between an experimental group (n = 10), in which severe isovolemic hemodilution was performed with 6% hydroxyethylstarch (1:1), and a time-matched control group (n = 5). Systemic, intestinal, and cerebral hemodynamic and oxygenation parameters were monitored. Microvascular oxygen partial pressure (muPo(2) ) was measured in the cerebral cortex and the intestinal serosa and mucosa, using the oxygen-dependent quenching of Pd-porphyrin phosphorescence. In the final phase of the experiment, fraction of inspired oxygen was increased to 1.0. Results Hemodilution decreased hematocrit from 25.3 +/- 3.0 to 7.6 +/- 1.2% (mean +/- SD). Systemic and intestinal oxygen delivery fell with the onset of hemodilution; intestinal oxygen consumption deceased at a hematocrit of 9.9%, whereas the systemic oxygen consumption decreased at a hematocrit of 7.6%. During hemodilution, the intestinal and cerebral oxygen extraction ratios increased from baseline with 130 and 52%, respectively. Based on the intersection of the two best-fit regression lines, determined by a least sum of squares technique, similar critical hematocrit levels were found for systemic oxygen consumption and the cerebral and intestinal mucosa muPo(2); the intestinal serosa muPo(2) decreased at an earlier stage (P < 0.05). Hyperoxic ventilation improved the muPo(2) values but not systemic or intestinal oxygen consumption. Conclusions During isovolemic hemodilution, the diminished oxygen supply was redistributed in favor of organs with a lower capacity to increase oxygen extraction. It is hypothesized that redirection of the oxygen supply within the intestines resulted in the preservation of oxygen consumption and mucosal muPo(2) compared with serosal muPo(2).

Cardiovascular and Metabolic Response to Acute Normovolemic Anemia

2000 ◽  
Vol 93 (4) ◽  
pp. 1011-1016 ◽  
Author(s):  
Brigitte E. Ickx ◽  
Michel Rigolet ◽  
Philippe J. Van der Linden
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Cardiac Index ◽  
Oxygen Delivery ◽  
Oxygen Extraction ◽  
Stroke Index ◽  
Acute Normovolemic Hemodilution ◽  
Output Response ◽  
Anesthetic Drugs ◽  
Normovolemic Hemodilution

Background The maintenance of adequate tissue oxygenation during acute anemia depends on an increase in both cardiac output and tissue oxygen extraction. This study tested the hypothesis that anesthesia blunts the cardiac output response associated with acute normovolemic hemodilution. Methods Forty patients undergoing major abdominal surgery were prospectively randomized to undergo acute normovolemic hemodilution (ANH) either awake (awake group, n = 20) or with fentanyl-nitrous oxide-isoflurane anesthesia (anesthetized group, n = 20). Radial and pulmonary artery catheters were placed in all patients. After hemodynamic measurements were taken, patients in the two groups underwent hemodilution to decrease their hemoglobin concentration from 13 to 8 g/dl. A total of 1,875 +/- 222 ml (mean +/- SD) of blood was collected and simultaneously replaced by the same volume of medium molecular weight hydroxyethylstarch in both groups. Results In the awake group, ANH resulted in a significant increase in cardiac index (from 3.1 +/- 0.5 to 4.8 +/- 1.0 l. min-1. m-2) related to both an increase in heart rate and stroke index. Oxygen delivery remained unchanged, but oxygen consumption increased significantly, resulting in an increase in oxygen extraction ratio. In the anesthetized group, ANH resulted in a significantly smaller increase in cardiac index (from 2.3 +/- 0.5 to 3.1 +/- 0.7 l. min-1. m-2) related solely to an increase in stroke index. Oxygen delivery decreased but oxygen consumption was maintained as oxygen extraction increased. Conclusions Anesthesia significantly reduces the cardiac output response associated with ANH. This could be related to the effects of the anesthetic drugs on the autonomic and the cardiovascular systems.

alpha-Adrenergic control of oxygen delivery to myocardium during exercise in conscious dogs

1982 ◽  
Vol 242 (5) ◽  
pp. H805-H809 ◽  
Author(s):  
G. R. Heyndrickx ◽  
P. Muylaert ◽  
J. L. Pannier
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Coronary Blood Flow ◽  
Coronary Sinus ◽  
Oxygen Delivery ◽  
Left Ventricular ◽  
Conscious Dogs ◽  
Adrenergic Blockade ◽  
Adrenergic Control

alpha-Adrenergic control of the oxygen delivery to the myocardium during exercise was investigated in eight conscious dogs instrumented for chronic measurements of coronary blood flow, left ventricular (LV) pressure, aortic blood pressure, and heart rate and sampling of arterial and coronary sinus blood. After alpha-adrenergic receptor blockade a standard exercise load elicited a significantly greater increase in heart rate, rate of change of LV pressure (LV dP/dt), LV dP/dt/P, and coronary blood flow than was elicited in the unblocked state. In contrast to the response pattern during control exercise, there was no significant change in coronary sinus oxygen tension (PO2), myocardial arteriovenous oxygen difference, and myocardial oxygen delivery-to-oxygen consumption ratio. It is concluded that the normal relationship between myocardial oxygen supply and oxygen demand is modified during exercise after alpha-adrenergic blockade, whereby oxygen delivery is better matched to oxygen consumption. These results indicate that the increase in coronary blood flow and oxygen delivery to the myocardium during normal exercise is limited by alpha-adrenergic vasoconstriction.

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