Relation between systemic oxygen uptake and tissue oxygen extraction following cardiac surgery

Objective: Adequacy of organ perfusion depends on sufficient oxygen supply in relation to the metabolic needs. The aim of this study was to evaluate the relationship between gradients of free energy change, and the more commonly used parameter for the evaluation of the adequacy of organ perfusion, such as oxygen-extraction in patients undergoing valve replacement surgery using normothermic cardiopulmonary bypass (CPB). Methods: In 43 cardiac patients, arterial, mixed venous, and hepato-venous blood samples were taken synchronously after induction of anaesthesia (preCPB), during CPB, and 2 and 7 h after admission to the intensive care unit (ICU+2, ICU+7). Blood gas analysis, cardiac output, and hepato-splanchnic blood flow were measured. Free energy change gradients between mixed venous and arterial (-ΔΔG(v-a)) and hepato-venous and arterial (-ΔΔG(hv-a)) compartments were calculated. Measurements and results: Cardiac index (CI) increased from 1.9 (0.7) to 2.8 (1.3) L/min/m (median, inter-quartile range) (p =0.001), and hepato-splanchnic blood flow index (HBFI) from 0.6 (0.22) to 0.8 (0.53) L/min/m (p =0.001). Despite increasing flow, systemic oxygen extraction increased after CPB from 24 (10)% to 35 (10)% at ICU+2 (p =0.002), and splanchnic oxygen extraction increased during CPB from 37 (19)% to 52 (14)% (p =0.001), and remained high thereafter. After CPB, high splanchnic and systemic gradients of free energy change gradients were associated with high splanchnic and systemic oxygen extraction, respectively (p =0.001, 0.033, respectively). Conclusion: Gradients of free energy change may be helpful in characterising adequacy of perfusion in cardiac surgery patients independently from measurements or calculations of data from oxygen transport.

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Impaired systemic oxygen extraction in treated exercise pulmonary hypertension: a new engine in an old car?

Pulmonary Circulation ◽

10.1177/2045893218755325 ◽

2018 ◽

Vol 8 (1) ◽

pp. 204589321875532 ◽

Cited By ~ 3

Author(s):

Mariana Faria-Urbina ◽

Rudolf K.F. Oliveira ◽

Sergio A. Segrera ◽

Laurie Lawler ◽

Aaron B. Waxman ◽

...

Keyword(s):

Skeletal Muscle ◽

Pulmonary Hypertension ◽

Oxygen Uptake ◽

Maximum Oxygen Uptake ◽

Oxygen Extraction ◽

Pulmonary Hemodynamics ◽

Maximum Exercise ◽

Systemic Oxygen

Ambrisentan in 22 patients with pulmonary hypertension diagnosed during exercise (ePH) improved pulmonary hemodynamics; however, there was only a trend toward increased maximum oxygen uptake (VO2max) secondary to decreased maximum exercise systemic oxygen extraction (Ca-vO2). We speculate that improved pulmonary hemodynamics at maximum exercise “unmasked” a pre-existing skeletal muscle abnormality.

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Tissue oxygen saturation changes and postoperative complications in cardiac surgery: a prospective observational study

BMC Anesthesiology ◽

10.1186/s12871-019-0905-5 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Sabino Scolletta ◽

Federico Franchi ◽

Elisa Damiani ◽

Armando Cennamo ◽

Roberta Domizi ◽

...

Keyword(s):

Cardiac Surgery ◽

Observational Study ◽

Oxygen Saturation ◽

Prospective Observational Study ◽

Near Infrared ◽

Oxygen Extraction ◽

Tissue Oxygen Saturation ◽

Tissue Oxygen ◽

University Hospitals ◽

Microvascular Reactivity

Abstract Background Cardiac surgery with extracorporeal circulation (ECC) can induce microvascular dysfunction and tissue hypoperfusion. We hypothesized that the alterations in near-infrared spectroscopy (NIRS)-derived parameters would be associated with post-operative complications in cardiac surgery patients. Methods Prospective observational study performed at two University Hospitals. Ninety patients undergoing cardiac surgery with ECC were enrolled. The NIRS sensor was applied on the thenar eminence. A vascular occlusion test (VOT, 3-min ischemia) was performed at baseline (t0), at Intensive Care Unit (ICU) admission (t1), 3 (t2) and 6 (t3) hours later. Baseline tissue oxygen saturation (StO2), oxygen extraction rate and microvascular reactivity indices were calculated. Results In the first hours after cardiac surgery, StO2 tended to increase (86% [80–89] at T3 versus 82% [79–86] at T0, p = ns), while both tissue oxygen extraction and microvascular reactivity tended to decrease, as indicated by increasing occlusion slope (− 8.1%/min [− 11.2 to − 7] at T3 versus − 11.2%/min [− 13.9 to − 7.9] at T0, p = ns) and decreasing recovery slope (1.9%/sec [1.1–2.9] at T3 versus 3.1%/sec [2.3–3.9] at T0, p = ns). No substantial differences were found in NIRS-derived variables and their changes over time between patients with complications and those without complications. Conclusions Peripheral tissue oxygen extraction and microvascular reactivity were reduced during the first hours after cardiac surgery. NIRS-derived parameters were not able to predict complications in this population of cardiac surgery patients.

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Systemic microvascular shunting through hyperdynamic capillaries after acute physiological disturbances following cardiopulmonary bypass

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00397.2014 ◽

2014 ◽

Vol 307 (7) ◽

pp. H967-H975 ◽

Cited By ~ 28

Author(s):

Nick J. Koning ◽

Lotte E. Simon ◽

Pierre Asfar ◽

Christophe Baufreton ◽

Christa Boer

Keyword(s):

Cardiac Surgery ◽

Cardiopulmonary Bypass ◽

Oxygen Extraction ◽

Capillary Perfusion ◽

Microcirculatory Perfusion ◽

Off Pump ◽

Sidestream Darkfield ◽

Systemic Oxygen ◽

The Relationship ◽

Oxygen Difference

Previously we showed that cardiopulmonary bypass (CPB) during cardiac surgery is associated with reduced sublingual microcirculatory perfusion and oxygenation. It has been suggested that impaired microcirculatory perfusion may be paralleled by increased heterogeneity of flow in the microvascular bed, possibly leading to arteriovenous shunting. Here we investigated our hypothesis that acute hemodynamic disturbances during extracorporeal circulation indeed lead to microcirculatory heterogeneity with hyperdynamic capillary perfusion and reduced systemic oxygen extraction. In this single-center prospective observational study, patients undergoing cardiac surgery with ( n = 18) or without ( n = 13) CPB were included. Perioperative microcirculatory perfusion was assessed sublingually with sidestream darkfield imaging, and recordings were quantified for microcirculatory heterogeneity and hyperdynamic capillary perfusion. The relationship with hemodynamic and oxygenation parameters was analyzed. Microcirculatory heterogeneity index increased substantially after onset of CPB [0.5 (0.0–0.9) to 1.0 (0.3–1.3); P = 0.031] but not during off-pump surgery. Median capillary red blood cell (RBC) velocity increased intraoperatively in the CPB group only [1,600 (913–2,500 μm/s) vs. 380 (190–480 μm/s); P < 0.001], with 31% of capillaries supporting high RBC velocities (>2,000 μm/s). Hyperdynamic microcirculatory perfusion was associated with reduced arteriovenous oxygen difference and systemic oxygen consumption during and after CPB. The current study provides the first direct human evidence for a microvascular shunting phenomenon through hyperdynamic capillaries following acute physiological disturbances after onset of CPB. The hypothesis of impaired systemic oxygen offloading caused by hyperdynamic capillaries was supported by reduced blood arteriovenous oxygen difference and low systemic oxygen extraction associated with CPB.

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Pulmonary hemodynamics and vascular reactivity in asphyxiated term lambs resuscitated with 21 and 100% oxygen

Journal of Applied Physiology ◽

10.1152/japplphysiol.00711.2011 ◽

2011 ◽

Vol 111 (5) ◽

pp. 1441-1447 ◽

Cited By ~ 39

Author(s):

Satyan Lakshminrusimha ◽

Robin H. Steinhorn ◽

Stephen Wedgwood ◽

Fabio Savorgnan ◽

Jayasree Nair ◽

...

Keyword(s):

Oxygen Uptake ◽

Vascular Reactivity ◽

Oxidant Stress ◽

Neonatal Resuscitation ◽

Birth Asphyxia ◽

Oxygen Extraction ◽

Superoxide Anions ◽

Pulmonary Hemodynamics ◽

Resuscitation Guidelines ◽

Systemic Oxygen

An increase in oxygen tension is an important factor in decreasing pulmonary vascular resistance (PVR) at birth. Birth asphyxia results in acidosis and increased PVR. We determined the effect of resuscitation with 21 vs. 100% O2 on pulmonary hemodynamics, pulmonary arterial (PA) reactivity, and oxidant stress in a lamb model of in utero asphyxia. Term fetal lambs were acutely asphyxiated by intrauterine umbilical cord occlusion for 10 min resulting in acidosis (pH 6.96 ± 0.05 and Pco2 103 ± 5 Torr), bradycardia, systemic hypotension, and increased PVR. Lambs were treated with 30 min of resuscitation with 21% or 100% O2 ( n = 6 each). PaO2 was significantly elevated with 100% O2 resuscitation compared with 21% O2 (430 ± 38 vs. 64 ± 8 Torr), but changes in pH and PaCO2 were similar. The 100% O2 induced greater increase in pulmonary blood flow and decrease in PVR at 1 min of life, but subsequent values were similar to 21% O2 group between 2 and 30 min of life. Oxygen uptake from the lung and systemic oxygen extraction was similar between the two groups. Pulmonary arteries showed increased staining for superoxide anions and increased contractility to norepinephrine following resuscitation with 100% O2. The increased PA contractility induced by 100% O2 was reversed by scavenging superoxide anions with superoxide dismutase and catalase. We conclude that resuscitation of asphyxiated lambs with 100% O2 increases PaO2 but does not improve lung oxygen uptake, decrease PVR at 30 min, or increase systemic oxygen extraction ratios. Furthermore, 100% O2 also induces oxidative stress and increases PA contractility. These findings support the new neonatal resuscitation guidelines recommending 21% O2 for initial resuscitation of asphyxiated neonates.

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Circulatory changes in man during mild supine exercise

Journal of Applied Physiology ◽

10.1152/jappl.1961.16.2.279 ◽

1961 ◽

Vol 16 (2) ◽

pp. 279-282 ◽

Cited By ~ 29

Author(s):

John T. Reeves ◽

Robert F. Grover ◽

Giles F. Filley ◽

S. Gilbert Blount

Keyword(s):

Cardiac Output ◽

Oxygen Uptake ◽

Oxygen Transport ◽

Oxygen Extraction ◽

Tissue Oxygen ◽

Total Blood ◽

Normal Men ◽

Total Blood Flow ◽

Extraction Mechanisms ◽

Oxygen Difference

Cardiac output and femoral A-V oxygen difference were measured in each of seven normal men at rest and during several stints of supine exercise to investigate the mechanisms of oxygen transport for stepwise increments of oxygen uptake. The femoral A-V oxygen difference increased sharply for mild exercise and showed smaller further increase for heavier exercise stints. The pulmonary A-V oxygen difference followed a similar behavior where the changes were of smaller magnitude. For mild exercise, increasing oxygen transport apparently depends to a greater extent on increasing femoral tissue oxygen extraction and to a lesser extent on increased femoral and total blood flow. For heavier exertion, increasing oxygen transport depends to a greater extent on increasing flow and to a smaller extent on a widening tissue oxygen extraction. Mechanisms which are utilized to meet the increased metabolic demands of exercise depend in part upon the severity of the exertion. Cardiac output appears not to be a simple linear function of oxygen uptake for various metabolic demands ranging from rest to heavy exercise. Submitted on August 8, 1960

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