scholarly journals Population data provide evidence against the presence of a set point for hemoglobin levels or tissue oxygen delivery

2019 ◽  
Vol 7 (12) ◽  
Author(s):  
Stephen P. Fitzgerald ◽  
Niels Grote Beverborg ◽  
Yves Beguin ◽  
Ferruh Artunc ◽  
Henrik Falhammar ◽  
...  
Keyword(s):  
Oxygen Delivery ◽  
Population Data ◽  
Tissue Oxygen ◽  
Set Point ◽  
Tissue Oxygen Delivery

Pulse oximetry

2007 ◽  
pp. 327-330
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Optical Density ◽  
Oxygen Delivery ◽  
Tissue Oxygen ◽  
Non Invasive ◽  
Tissue Oxygen Delivery ◽  
Invasive Method ◽  
Beer’S Law ◽  
Light Absorbance

Pulse oximetry 328 When employed correctly, pulse oximetry is a rapid non-invasive method of assessing one of the key components of tissue oxygen delivery: the oxygen saturation of haemoglobin (SaO2). • Based on the laws of light absorbance and optical density (Lambert's law and Beer's law), i.e. the principle that deoxygenated and oxygenated hemoglobin absorb light at different wavelengths....

Acute isovolemic anemia in anesthetized chickens

1976 ◽  
Vol 231 (5) ◽  
pp. 1451-1456 ◽  
Author(s):  
TE Nightingale
Keyword(s):  
Cardiac Output ◽  
Oxygen Delivery ◽  
Peripheral Resistance ◽  
Right Atrial ◽  
Tissue Oxygen ◽  
Cardiovascular Failure ◽  
Oxygen Transport Capacity ◽  
Dextran 70 ◽  
Tissue Oxygen Delivery ◽  
Viscosity Changes

Acute isovolemic anemia was produced in anesthetized chickens by serial exchanges of 6% dextran 70 equal to 1% of body weight to quantitate cardiovascular and metabolic parameters. When hematocrit (Hct) and hemoglobin (Hb) levels were reduced by 50% (from 33.3 to 16.3 vol %, and from 10.3 to 5.4 g/100 g, respectively, P less than 0.001), tissue oxygen delivery was maintained by increases in cardiac output (CO), stroke volume (SV), oxygen extraction, and reduced total peripheral resistance (TPR). Heart rate, right atrial pressure, and oxygen consumption (Vo2) were unchanged. Further reductions in Hct and Hb (to 10.8 vol % and 3.7 g/100 g, respectively), were accompanied by cardiovascular failure, as evidenced by falling CO, SV, tissue oxygen delivery, and Vo2. Relative apparent viscosity determinations on the exchanged blood-dextran mixtures indicated that large viscosity changes occurred with the first exchange whereas subsequent exchanges had small incremental viscosity changes. These data indicate that in acutely anemic chickens, oxygen transport capacity was maintained by increased cardiac output and decreased peripheral resistance, unless the severity of the anemia resulted in cardiovascular failure.

scholarly journals Cremaster muscle perfusion, oxygenation, and heterogeneity revealed by a new automated acquisition system in a rodent model of prolonged hemorrhagic shock

2019 ◽  
Vol 127 (6) ◽  
pp. 1548-1561
Author(s):  
Ivo P. Torres Filho ◽  
David Barraza ◽  
Kim Hildreth ◽  
Charnae Williams ◽  
Michael A. Dubick
Keyword(s):  
Hemorrhagic Shock ◽  
Oxygen Delivery ◽  
Repeated Measurements ◽  
Laser Speckle ◽  
Automated System ◽  
Cremaster Muscle ◽  
Tissue Oxygen ◽  
Hypoxia Ischemia ◽  
Tissue Oxygen Delivery ◽  
Muscle Homeostasis

Local blood flow/oxygen partial pressure (Po2) distributions and flow-Po2 relationships are physiologically relevant. They affect the pathophysiology and treatment of conditions like hemorrhagic shock (HS), but direct noninvasive measures of flow, Po2, and their heterogeneity during prolonged HS are infrequently presented. To fill this void, we report the first quantitative evaluation of flow-Po2 relationships and heterogeneities in normovolemia and during several hours of HS using noninvasive, unbiased, automated acquisition. Anesthetized rats were subjected to tracheostomy, arterial/venous catheterizations, cremaster muscle exteriorization, hemorrhage (40% total blood volume), and laparotomy. Control animals equally instrumented were not subjected to hemorrhage/laparotomy. Every 0.5 h for 4.5 h, noninvasive laser speckle contrast imaging and phosphorescence quenching were employed for nearly 7,000 flow/Po2 measurements in muscles from eight animals, using an automated system. Precise alignment of 16 muscle areas allowed overlapping between flow and oxygenation measurements to evaluate spatial heterogeneity, and repeated measurements were used to estimate temporal heterogeneity. Systemic physiological parameters and blood chemistry were simultaneously assessed by blood samplings replaced with crystalloids. Hemodilution was associated with local hypoxia, but increased flow prevented major oxygen delivery decline. Adding laparotomy and prolonged HS resulted in hypoxia, ischemia, decreased tissue oxygen delivery, and logarithmic flow/Po2 relationships in most regions. Flow and Po2 spatial heterogeneities were higher than their respective temporal heterogeneities, although this did not change significantly over the studied period. This quantitative framework establishes a basis for evaluating therapies aimed at restoring muscle homeostasis, positively impacting outcomes of civilian and military trauma/HS victims. NEW & NOTEWORTHY This is the first study on flow-Po2 relationships during normovolemia, hemodilution, and prolonged hemorrhagic shock using noninvasive methods in multiple skeletal muscle areas of monitored animals. Automated flow/Po2 measurements revealed temporal/spatial heterogeneities, hypoxia, ischemia, and decreased tissue oxygen delivery after trauma/severe hemorrhage. Hemodilution was associated with local hypoxia, but hyperemia prevented a major decline in oxygen delivery. This framework provides a quantitative basis for testing therapeutics that positively impacts muscle homeostasis and outcomes of trauma/hemorrhagic shock victims.

The Effect of Hypothermia on the Oxygen Delivery to Cerebral Tissue: Analysis Using a Compartmental Model

2004 ◽  
Author(s):  
Obdulia Ley ◽  
Yildiz Bayazitoglu
Keyword(s):  
Oxygen Delivery ◽  
Compartmental Model ◽  
Effect Of Temperature ◽  
Oxygen Absorption ◽  
Tissue Analysis ◽  
Tissue Oxygen ◽  
Oxygen Dissociation ◽  
Tissue Oxygen Delivery ◽  
Effects Of Temperature ◽  
Tissue Compartments

This paper studies the effect of temperature in the cerebral oxygen absorption and delivery using a compartmental model of oxygen transport which introduces the temperature dependence of factors such as the cerebral blood flow, the oxygen dissociation curve, and the tissue metabolic activity. The variations of the oxygen delivered to the tissue for the case of normoxia and hypoxia are studied, as well as the tissue oxygen delivery during different cooling strategies. The goal of the present study is to understand the effects of temperature in the oxygen uptake, and to determine a safe temperature limits for hypothermic treatment maximizing tissue oxygen delivery. From the calculations it is seen that the oxygen content falls in the vascular and tissue compartments during hypothermia and that this effect is aggravated by hypoxia.

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