scholarly journals Dynamic estimation of the myocardial oxygen extraction ratio during dipyridamole stress by MRI: A preliminary study in canines

2004 ◽  
Vol 51 (4) ◽  
pp. 718-726 ◽  
Author(s):  
Jie Zheng ◽  
Jinghua Wang ◽  
Mark Nolte ◽  
Debiao Li ◽  
Robert J. Gropler ◽  
...  
Keyword(s):  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Oxygen Extraction Ratio ◽  
Dynamic Estimation ◽  
Preliminary Study ◽  
Myocardial Oxygen Extraction ◽  
Dipyridamole Stress

Is Calcium a Coronary Vasoconstrictor In Vivo? 

1998 ◽  
Vol 88 (3) ◽  
pp. 735-743 ◽  
Author(s):  
George J. Crystal ◽  
Xiping Zhou ◽  
Ramez M. Salem
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Coronary Blood Flow ◽  
Myocardial Oxygen Consumption ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Oxygen Extraction Ratio ◽  
Myocardial Oxygen Extraction ◽  
Dose Dependent

Background Calcium produces constriction in isolated coronary vessels and in the coronary circulation of isolated hearts, but the importance of this mechanism in vivo remains controversial. Methods The left anterior descending coronary arteries of 20 anesthetized dogs whose chests had been opened were perfused at 80 mmHg. Myocardial segmental shortening was measured with ultrasonic crystals and coronary blood flow with a Doppler flow transducer. The coronary arteriovenous oxygen difference was determined and used to calculate myocardial oxygen consumption and the myocardial oxygen extraction ratio. The myocardial oxygen extraction ratio served as an index of effectiveness of metabolic vasodilation. Data were obtained during intracoronary infusions of CaCl2 (5, 10, and 15 mg/min) and compared with those during intracoronary infusions of dobutamine (2.5, 5.0, and 10.0 microg/min). Results CaCl2 caused dose-dependent increases in segmental shortening, accompanied by proportional increases in myocardial oxygen consumption. Although CaCl2 also increased coronary blood flow, these increases were less than proportional to those in myocardial oxygen consumption, and therefore the myocardial oxygen extraction ratio increased. Dobutamine caused dose-dependent increases in segmental shortening and myocardial oxygen consumption that were similar in magnitude to those caused by CaCl2. In contrast to CaCl2, however, the accompanying increases in coronary blood flow were proportional to the increases in myocardial oxygen consumption, with the result that the myocardial oxygen extraction ratio remained constant. Conclusions Calcium has a coronary vasoconstricting effect and a positive inotropic effect in vivo. This vasoconstricting effect impairs coupling of coronary blood flow to the augmented myocardial oxygen demand by metabolic vascular control mechanisms. Dobutamine is an inotropic agent with no apparent direct action on coronary resistance vessels in vivo.

Myocardial oxygen extraction ratio is decreased during endotoxemia in pigs

1995 ◽  
Vol 79 (2) ◽  
pp. 479-486 ◽  
Author(s):  
M. J. Herbertson ◽  
H. A. Werner ◽  
J. A. Russell ◽  
K. Iversen ◽  
K. R. Walley
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Left Ventricular ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Ventricular Contractility ◽  
Oxygen Extraction Ratio ◽  
Extraction Capacity ◽  
Myocardial Oxygen Extraction ◽  
Increased Blood Flow

Why the myocardial oxygen extraction ratio (ERm) is decreased during septic shock in humans is unknown. Therefore, we calculated ERm in 15 anesthetized pigs by measuring arterial and coronary venous oxygen content. We measured myocardial lactate flux, myocardial contractility, and global myocardial blood flow and its distribution. After baseline measurements, animals received either saline (n = 6) or 50 micrograms/kg of endotoxin (n = 9). Measurements were repeated for 4 h. After endotoxin, ERm decreased from 67 +/- 12% at baseline to 36 +/- 10% (P < 0.01) at 1 h and 54 +/- 10% (P < 0.05) at 4 h, associated with an increased myocardial blood flow that was heterogeneous. Neither myocardial oxygen nor lactate consumption decreased in the endotoxin group, and changes in left ventricular contractility were not correlated with changes in ERm. We conclude that the decrease in ERm after endotoxin infusion is due to both increased blood flow and mismatching between myocardial oxygen delivery and demand. Impaired myocardial oxygen extraction capacity during sepsis did not cause global myocardial tissue hypoxia.

scholarly journals Evaluation of cellular oxygen extraction ratio in brachycephalic dogs: a pilot study

2015 ◽  
pp. 487-487
Author(s):  
Florence Vessieres ◽  
Geraldine Jourdan ◽  
Remi Gautier ◽  
Aurelie Zahra ◽  
Laurent Guenego ◽  
...  
Keyword(s):  
Pilot Study ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Oxygen Extraction Ratio ◽  
Cellular Oxygen

The Cerebral Oxygen Extraction Ratio during Propofol and Isoflurane Anesthesia

2000 ◽  
Vol 38 (5) ◽  
pp. 830
Author(s):  
Soon Ho Cheong ◽  
Nam Hak Heo ◽  
Jeong Hun Kim ◽  
Young Kyun Choe ◽  
Young Jae Kim ◽  
...  
Keyword(s):  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Cerebral Oxygen ◽  
Oxygen Extraction Ratio ◽  
Isoflurane Anesthesia

scholarly journals P1435RELATIONSHIP BETWEEN INTRA-DIALYTIC OXYGEN EXTRACTION RATIO (OER) CHANGE AND IDH

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Silverio Rotondi ◽  
Lida Tartaglione ◽  
Maria Luisa Muci ◽  
Sara Caissuti ◽  
Marzia Pasquali ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Poor Quality ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Intradialytic Hypotension ◽  
Oxygen Extraction Ratio ◽  
Median Percentage ◽  
Monitoring Instrument

Abstract Background and Aims Intradialytic hypotension (IDH) involves a reduced tolerance to hemodialysis (HD), a poor quality of life and is associated with mortality. Intradialytic monitoring systems (blood pressure, heart rate, volemia) are not able to identify patients at greater risk of IDH. IDH is a hemodynamic phenomenon and attention has recently been given to the evaluation of oxygen saturation to evaluate its role in IDH. Oxygen Extraction Ratio (OER), the ratio between SaO2 and ScvO2, is a parameter used to monitor parenchyma oxygen consumption and stress. Recent evidence showed that HD patients with a greater delta OER (ΔOER) during HD (threshold 40%)had higher mortality risk. OER could be a new monitoring instrument to measure hemodialysis induced sub-clinical parenchyma hypoxia and stress, two elements included in the pathogenesis of IDH. The aim of the study was to evaluate the relationship between OER and IDH incidence. Method Inclusion criteria: age ≥18 years, chronic HD treatment by means of permanent jugular CVC, no evidence of acute underlying illness. We evaluated OER ([(SaO2 − ScvO2)/SaO2] × 100) before HD and at 15’, 30’, 60’ and post HD in three HD sessions (HD OER sessions). For the statistic analysis we considered for each patient the median OER value obtained from the three HD OER sessions. Then we started the follow-up study with a minimum follow-up of three months and end follow-up of two years, to record IDH (defined according to K/DOQI guidelines) for each patient. We divided the population in two groups using as a threshold the median percentage number of IDH in our population and evaluate the differences between the obtained two groups in pre HD OER, Delta OER and intradialytic OER trends. Results During the follow-up period (mean 12 ± 1.2 months), we enrolled 28 patients with permanent jugular CVC: 13 males and 15 females, aged 74±2.6 years, HD vintage 46 ± 6.5 months. The HD OER sessions for each patient were asymptomatic. Pre HD OER was 34 ± 1.4, post HD OER 46 ± 1.8, with a Delta OER of 39 ± 5 %. OER change during HD was evident since after 15 minutes (OER% 15’: 40 ± 1.2 p&lt;.001) and continued to increase progressively (OER% end HD 46 ± 1.8; p&lt;.0001). During the follow up period we monitored 4342 HD sessions of which 186 with IDH, the median incidence of IDH was 3.6% of all HD sessions. We divided patients into two groups based on the median value of IDH incidence: (IDH % ≤ 3.6 and IDH % &gt; 3.6). The two groups were not different for age (76 ± 2.4 vs 73 ± 3.0 years; p &lt;ns), HD vintage (52 ± 8.6 vs 40 ± 4.0 months; p &lt;ns), systolic (125 ± 3.2 vs 129 ± 4.0 mmHg; p &lt;ns) and diastolic blood pressure (67 ± 2.2 vs 70 ± 2.2 mmHg; p &lt;ns) and heart rate (70 ± 2.2 vs. 76 ± 2.3 bpm; p &lt;ns) (Tab. 2). The IDH % &gt;3.6 group had 159 IDH out of a total of 1911 sessions (9%), while IDH % ≤ 3.6 group had 27 IDH out of 2431 sessions (0.9%). Pre HD OER values were not different between the groups while the IDH % &gt;3.6 group had greater delta OER% than the IDH % ≤ 3.6 group (43 ± 4.8 vs. 35 ± 3.0 %; p &lt;.05) (Figure). Evaluating the OER trend during HD session a higher ΔOER% was found at 15 minutes of HD treatment in the IDH % &gt; 3.6 group (ΔOER 20± 3.0 % vs. 8.0 ± 3.0 %; IDH % &gt; 3.6 group vs. IDH % ≤ 3.6 group, p &lt;.05), data confirmed at 30' (24 ± 3.0 % vs. 13 ± 5.0 %; p &lt;.05), and post HD (43 ± 5.0 % vs 35 ± 3.0 %; p &lt;.05), but not at 60 minutes of HD treatment (19 ± 4.0 % vs. 17 ± 4.6 %; p &lt;ns). Conclusion Our data show that intradialytic ΔOER, representative of the extent of tissue hypoxic stress, identifies patients at greater risk of IDH. In particular, a ΔOER of 20% after the first 15 minutes of HD and of 43% at the end of the HD session characterizes the more hemodynamically fragile patients. The measurement of the OER can be a new and easy monitoring instrument to identify the most hemodynamically fragile patients already after the first 15 minutes of HD treatment.

The physiologic reserve in oxygen carrying capacity: studies in experimental hemodilution

1986 ◽  
Vol 64 (1) ◽  
pp. 7-12 ◽  
Author(s):  
C. K. Chapler ◽  
S. M. Cain
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Oxygen Supply ◽  
The Body ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Whole Body ◽  
Oxygen Extraction Ratio ◽  
Acute Anemia ◽  
Total Body Oxygen

The mechanisms by which the body attempts to avoid tissue hypoxia when total body oxygen delivery is compromised during acute anemia are reviewed. When the hematocrit is reduced by isovolemic hemodilution the compensatory adjustments include an increase in cardiac output, redistribution of blood flow to some tissues, and an increase in the whole body oxygen extraction ratio. These responses permit whole body oxygen uptake to be maintained until the hematocrit has been lowered to about 10%. Several factors are discussed which contribute to the increase in cardiac output during acute anemia including the reduction in blood viscosity, sympathetic innervation of the heart, and increased venomotor tone. The latter has been shown to be dependent on intact aortic chemoreceptors. With respect to peripheral vascular responses, the rise in coronary and cerebral blood flows which occur following hemodilution is proportionally greater than the increase in cardiac output while the opposite is true for kidney, liver, spleen, and intestine. Skeletal muscle does not contribute to a redistribution of blood flow to more vital areas during acute anemia despite its relatively large anaerobic capacity. Overall, peripheral compensatory adjustments result in an increased oxygen extraction ratio during acute anemia which reflects a better matching of the limited oxygen supply to tissue oxygen demands. However, some areas such as muscle are relatively overperfused which limits an even more efficient utilization of the reduced oxygen supply. Studies of the response of the microcirculation and the extent to which sympathetic vascular controls are involved in peripheral blood flow regulation are necessary to further appreciate the complex pattern of physiological responses which help ensure survival of the organism during acute anemia.

Changes in gut intramucosal pH and gut oxygen extraction ratio in a porcine model of peritonitis and hemorrhage

1995 ◽  
Vol 23 (11) ◽  
pp. 1872-1881 ◽  
Author(s):  
Jan B. Antonsson ◽  
Lennart Engstrom ◽  
Ib Rasmussen ◽  
Staffan Wollert ◽  
Ulf H. Haglund
Keyword(s):  
Porcine Model ◽  
Extraction Ratio ◽  
Oxygen Extraction ◽  
Oxygen Extraction Ratio ◽  
Intramucosal Ph
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