Perinatal Blood Loss

1990 ◽  
Vol 12 (2) ◽  
pp. 47-53
Author(s):  
Richard A. Molteni
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Oxygen Delivery ◽  
Cell Mass ◽  
Hypovolemic Shock ◽  
Fetal Life ◽  
Tissue Oxygen ◽  
Screening Process ◽  
Cell Numbers ◽  
Tissue Oxygen Delivery

In recent years a great deal of attention has been paid to the evaluation and treatment of conditions characterized by red blood cell excess (polycythemia). The debatable practice of routine newborn hematocrit screening was initiated and perpetuated by the still uncertain short-term and long-term complications of polycythemia and its commonly associated state of hyperviscosity. Previously unsuspected anemia is often identified during this same screening process. Unless profound (leading to hypovolemic shock) or associated with more visible signs of hemolysis (jaundice), the etiology of this state of diminished red blood cell mass is often ignored or evaluated incompletely. This review focuses on the effects of anemia in the fetus and neonate, discusses mechanisms of fetal red blood cell production, and provides a basic diagnostic approach for the clinician when anemia is recognized in the neonatal period. PHYSIOLOGIC EFFECTS OF RED CELL REDUCTION Tissue Oxygen Delivery Maintenance of adequate red blood cell numbers can be even more critical during fetal life than during the postnatal period. The fetus, dependent upon maternal oxygen sources, cannot raise tissue oxygen delivery acutely by increasing placental oxygen transfer, even when its red blood cell numbers are decreased. Total oxygen content (sum of oxygen dissolved in plasma and bound to hemoglobin) of the blood is dependent upon both the partial pressure of oxygen (Pao2) and the quantity of hemoglobin available.

Postnatal regulation of oxygen delivery: hematologic parameters of postnatal dogs

1979 ◽  
Vol 237 (1) ◽  
pp. H71-H75 ◽  
Author(s):  
P. A. Mueggler ◽  
J. S. Peterson ◽  
R. D. Koler ◽  
J. Metcalfe ◽  
J. A. Black
Keyword(s):  
Oxygen Delivery ◽  
Cell Mass ◽  
Oxygen Affinity ◽  
Oxygen Demand ◽  
Hemoglobin Concentration ◽  
Postnatal Life ◽  
Red Cell ◽  
Tissue Oxygen ◽  
Red Cell Mass ◽  
Tissue Oxygen Delivery

Hematologic parameters influencing tissue oxygen delivery in dogs during the first 4 mo of life have been investigated. The rapid growth and increase in body temperature during this period imply an increased metabolic rate and increased tissue oxygen demand. Hemoglobin concentration and hematocrit decrease during the 1st mo following birth. The total red cell mass does not decrease during this period. The observed hemodilution can be attributed to an increasing plasma volume in the growing animal. The blood oxygen affinity decreases during this same period, resulting in a more effective tissue oxygen delivery. Erythropoiesis, as estimated from the percent circulating reticulocytes, decreases following birth and does not increase until 1 mo of postnatal life. The increase of erythropoietic activity during the 2nd mo of postnatal life coincides with an increase in red cell mass, hematocrit, and hemoglobin concentration.

Red blood cell as glucose carrier: significance for placental and cerebral glucose transfer

1984 ◽  
Vol 246 (3) ◽  
pp. R289-R298 ◽  
Author(s):  
J. A. Jacquez
Keyword(s):  
Blood Cell ◽  
Glucose Transport ◽  
Blood Brain Barrier ◽  
Red Blood Cell ◽  
High Capacity ◽  
Brain Barrier ◽  
Fetal Life ◽  
Red Cell Membrane ◽  
Glucose Transfer ◽  
Blood Brain

At plasma glucose values of 5 mM (90 mg/100 ml) the maximum glucose transport capacity of the human red cell membrane is 12,000 times the rate of glucose utilization by the red blood cell. Mammals, other than primates, that have been tested have a comparable high-capacity system during fetal life, which is lost soon after birth. It has been suggested that the availability of the water space of the red blood cell for distribution of glucose facilitates transfer across the placenta during fetal life in all mammals and across the blood-brain barrier in adult primates. Though plausible, more comparative studies of glucose transport in red blood cells of other species and direct experimental evaluations of the contribution of the red blood cell to glucose transfer across the placenta and the blood-brain barrier are needed.

In vivo microvascular structural and functional consequences of muscle length changes

1997 ◽  
Vol 272 (5) ◽  
pp. H2107-H2114 ◽  
Author(s):  
D. C. Poole ◽  
T. I. Musch ◽  
C. A. Kindig
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Oxygen Delivery ◽  
Sarcomere Length ◽  
Flow Dynamics ◽  
Capillary Diameter ◽  
Luminal Diameter ◽  
Length Changes

As muscles are stretched, blood flow and oxygen delivery are compromised, and consequently muscle function is impaired. We tested the hypothesis that the structural microvascular sequellae associated with muscle extension in vivo would impair capillary red blood cell hemodynamics. We developed an intravital spinotrapezius preparation that facilitated direct on-line measurement and alteration of sarcomere length simultaneously with determination of capillary geometry and red blood cell flow dynamics. The range of spinotrapezius sarcomere lengths achievable in vivo was 2.17 +/- 0.05 to 3.13 +/- 0.11 microns. Capillary tortuosity decreased systematically with increases of sarcomere length up to 2.6 microns, at which point most capillaries appeared to be highly oriented along the fiber longitudinal axis. Further increases in sarcomere length above this value reduced mean capillary diameter from 5.61 +/- 0.03 microns at 2.4-2.6 microns sarcomere length to 4.12 +/- 0.05 microns at 3.2-3.4 microns sarcomere length. Over the range of physiological sarcomere lengths, bulk blood flow (radioactive microspheres) decreased approximately 40% from 24.3 +/- 7.5 to 14.5 +/- 4.6 ml.100 g-1.min-1. The proportion of continuously perfused capillaries, i.e., those with continuous flow throughout the 60-s observation period, decreased from 95.9 +/- 0.6% at the shortest sarcomere lengths to 56.5 +/- 0.7% at the longest sarcomere lengths and was correlated significantly with the reduced capillary diameter (r = 0.711, P < 0.01; n = 18). We conclude that alterations in capillary geometry and luminal diameter consequent to increased muscle sarcomere length are associated with a reduction in mean capillary red blood cell velocity and a greater proportion of capillaries in which red blood cell flow is stopped or intermittent. Thus not only does muscle stretching reduce bulk blood (and oxygen) delivery, it also alters capillary red blood cell flow dynamics, which may further impair blood-tissue oxygen exchange.

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....

Oxygen exchange in the microcirculation of hamster retractor muscle

1989 ◽  
Vol 256 (1) ◽  
pp. H247-H255 ◽  
Author(s):  
D. P. Swain ◽  
R. N. Pittman
Keyword(s):  
Blood Cell ◽  
Oxygen Saturation ◽  
Oxygen Tension ◽  
Red Blood Cell ◽  
Unit Length ◽  
Retractor Muscle ◽  
Tissue Oxygen ◽  
Hemoglobin Oxygen Saturation ◽  
First Order ◽  
Weighted Values

We determined percent hemoglobin oxygen saturation (SO2) in arterioles and venules of the hamster retractor muscle at rest. We found that SO2 decreased from 69.9 +/- 1.4% (SE) in large input arterioles (first order, 1A, ID = 60 +/- 3 micron) to flow-weighted values of 56.7% in small arterioles (4A, ID = 20 +/- 1 micron), 51.3% in small venules (4V, ID = 28 +/- 1 micron), and to 50.6 +/- 1.0% in large venules (1V, ID = 147 +/- 13 micron). Thus approximately two-thirds of the net decline in SO2 for this tissue occurred by diffusion of oxygen from arterioles, whereas only about one-third occurred by diffusion from capillaries. Furthermore, no net shunting of oxygen from the arterioles to the venules was detected as evidenced by the absence of any significant change in venular SO2. By determining the SO2 at upstream and downstream ends of arterioles in four consecutive branching orders (1A-4A), we found that the decrease in SO2 per unit length (delta SO2/L) increased approximately 20-fold from 1A to 4A. This increase in delta SO2/L was directly proportional to estimated luminal minus tissue oxygen tension and inversely proportional to red blood cell flow.

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.

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