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Singapore Medical Journal Aug 2002Under physiological conditions and on average, the total volume of blood in the circulation is constant. The total blood volume (BV) and the separate volumes of plasma... (Review)
Review
Under physiological conditions and on average, the total volume of blood in the circulation is constant. The total blood volume (BV) and the separate volumes of plasma and erythrocytes vary according to climatic conditions, in pregnancy and in the presence of disease. Such changes can have clinical significance although they are rarely revealed in common clinical practice because of a lack of availability of accurate, cheap and simple techniques for the measurement of BV. Diminution of BV may occur under intensive-care regimes and is life-threatening; acute exposure to a hot climate leads to an expansion of plasma volume and a corresponding fall in the circulating haemoglobin level. The same changes occur in normal pregnancy and are, perhaps, exaggerated in the tropics. Failure of expansion of PV in pregnancy has adverse effects on the foetus. New investigations in Singapore of BV in health, disease and pregnancy seem to be desirable now that people, including pregnant women, move frequently between a hot climate and a cold environment provided by air-conditioning.
Topics: Blood Volume; Environment, Controlled; Erythrocyte Volume; Female; Hematologic Tests; Hot Temperature; Humans; Plasma Volume; Pregnancy; Tropical Climate
PubMed: 12507031
DOI: No ID Found -
Applied Radiation and Isotopes :... Feb 2015In the last years, there has been a growing recognition of the importance of blood volume abnormalities in the pathophysiology of several conditions and, consequently, a... (Review)
Review
In the last years, there has been a growing recognition of the importance of blood volume abnormalities in the pathophysiology of several conditions and, consequently, a growing interest of accurate and rapid volume status assessment. Accordingly, there has been a surge of interest in blood volume analysis by radioisotopic dilution technique. However, there are still some controversies about this technique, such as the use of the f-cell ratio, the errors associated with the method and the reference values. This review aims to revise and discuss the theoretical and methodological aspects of this technique and also to discuss their controversies. Furthermore, it is questioned whether red cell volume or plasma volume can be accurately estimated once the other quantity has been measured or should red cell volume and plasma volume be directly measured. As a conclusion, blood volume analysis by radioisotopic dilution technique is still valid and very useful.
Topics: Adult; Anticoagulants; Blood Volume; Erythrocyte Volume; Female; Hematocrit; Hemolysis; Humans; Indicator Dilution Techniques; Male; Patient Positioning; Plasma Volume; Radioisotope Dilution Technique; Reference Values
PubMed: 25479437
DOI: 10.1016/j.apradiso.2014.11.014 -
Artificial Organs Oct 2021The monitoring of relative blood volume (RBV) changes during hemodialysis is increasingly used to evaluate the effect of dialyzer ultrafiltration on intravascular volume...
The monitoring of relative blood volume (RBV) changes during hemodialysis is increasingly used to evaluate the effect of dialyzer ultrafiltration on intravascular volume to guide the removal of excess fluid in a manner that maintains hemodynamic stability of the patient. RBV monitoring is typically based on an optical or acoustic sensor placed in the arterial blood line that measures a marker of hemoconcentration, such as hematocrit, hemoglobin, or total blood protein. However, the accuracy of RBV monitors and the impact of their clinical use remain the subject of ongoing debate. Here, we show that, depending on the procedure of filling the extracorporeal circuit with the patient's blood at the beginning of the dialysis session, the indications of an RBV monitor may be misleading as to the actual changes of the intravascular volume. When the blood is first pumped into the dialyzer, the priming fluid (saline) that fills the circuit may be either infused into the patient or disposed of to a drain bag. In the latter case, the intravascular volume is suddenly reduced, which is not accounted for by RBV monitors that track only the subsequent reductions in blood volume due to dialyzer ultrafiltration. We analyzed this general aspect of RBV monitoring using model-based simulations and showed quantitatively how RBV changes calculated using hematocrit differ depending on the priming procedure.
Topics: Blood Volume; Hematocrit; Humans; Models, Theoretical; Monitoring, Physiologic; Renal Dialysis; Saline Solution
PubMed: 33908070
DOI: 10.1111/aor.13972 -
The American Journal of the Medical... Jul 2007The kidney plays a pivotal role in the regulation of blood volume by controlling the plasma volume and red blood cell (RBC) mass. Further, it is proposed that the kidney... (Review)
Review
The kidney plays a pivotal role in the regulation of blood volume by controlling the plasma volume and red blood cell (RBC) mass. Further, it is proposed that the kidney coordinates the relative volumes of these 2 blood components and in so doing regulates the hematocrit. This novel function as proposed is a functional concept whereby the kidney does not simply produce erythropoietin, but that the kidney regulates the hematocrit is termed the critmeter function. The kidney is unique in that it can indirectly report on blood volume as a tissue oxygen signal. It is proposed that the kidneys detect small changes in tissue oxygen tension for erythropoietin production at the critmeter, a functional unit of marginal oxygen tension within the kidneys. As the production of erythropoietin is modulated by angiotensin II, the renin-angiotensin system entrains the production of erythropoietin as part of the effector signals of the feedback loop of blood volume regulation. Collectively, the consideration of these points generates a paradigm shift in our understanding of blood volume regulation in that the role of the kidney may be expanded from simply "producing" erythropoietin to regulating the hematocrit. Further, this concept broadens the scope of the traditionally identified effector mechanisms of plasma volume regulation to include the modulation of erythropoietin production and hence RBC mass. The inclusion of both plasma volume and RBC mass as factors targeted by the effector signals recapitulates that whole blood volume is sensed and reported in the afferent signals. In summary, distinct sensing and effector mechanisms for regulating the volume of the two components of whole blood (plasma and red cell mass) are recognized. The coupling of the regulation of these 2 components of blood volume is highlighted.
Topics: Blood Volume; Erythrocyte Volume; Erythropoietin; Feedback; Hematocrit; Humans; Kidney; Plasma Volume; Renin-Angiotensin System
PubMed: 17630596
DOI: 10.1097/MAJ.0b013e318095a4ae -
Acta Paediatrica (Oslo, Norway : 1992) Apr 2024
Topics: Humans; Cerebral Blood Volume; Blood Volume; Cerebrovascular Circulation
PubMed: 38229528
DOI: 10.1111/apa.17113 -
European Heart Journal Oct 1985
Topics: Blood Proteins; Blood Volume; Cardiac Output; Erythrocyte Volume; Hematocrit; Humans; Reference Values
PubMed: 4076224
DOI: 10.1093/eurheartj/6.suppl_c.41 -
The American Journal of the Medical... Jul 2007Body fluid regulation is affected by gravity. The primary mechanisms of the etiology of hypovolemia found in simulation studies on earth and after space flight are... (Review)
Review
Body fluid regulation is affected by gravity. The primary mechanisms of the etiology of hypovolemia found in simulation studies on earth and after space flight are different. The increased diuresis after increase of central blood volume postulated by Henry Gauer could not be found. Based on recent findings, new hypotheses about fluid volume regulation during space flight have emerged. The reduced blood volume in space is the result of 1) a negative balance of decreased fluid intake and smaller reduction of urine output; 2) fast fluid shifts from the intravascular to interstitial space as the result of lower transmural pressure after reduced compression of all tissue by gravitational forces especially of the thorax cage; and 3) fluid shifts from intravascular to muscle interstitial space because of less muscle tone required to maintain body posture. Additionally, loss of erythrocytes reduces blood volume. The attenuated diuresis during space flight can be explained by increased retention after stress-mediated sympathetic activation during initial phase of space flight, stimulation caused by reduced red cell mass, and activation after fast blood volume contraction. Additionally, the relation between plasma osmolarity and vasopressin release might be disturbed in microgravity.
Topics: Blood Volume; Fluid Shifts; Gravitation; Humans; Hypovolemia; Plasma Volume; Space Flight; Weightlessness; Weightlessness Countermeasures
PubMed: 17630598
DOI: 10.1097/MAJ.0b013e318065b89b -
The American Journal of the Medical... Jul 2007
Review
Topics: Blood Volume; Blood Volume Determination; Chromium Radioisotopes; Erythrocyte Volume; Humans; Iodine Radioisotopes; Plasma Volume; Serum Albumin
PubMed: 17630589
DOI: 10.1097/MAJ.0b013e318063c6d1 -
Medicine and Science in Sports and... Feb 2000This paper reviews the influence of several perturbations (physical exercise, heat stress, terrestrial altitude, microgravity, and trauma/sickness) on adaptations of... (Review)
Review
This paper reviews the influence of several perturbations (physical exercise, heat stress, terrestrial altitude, microgravity, and trauma/sickness) on adaptations of blood volume (BV), erythrocyte volume (EV), and plasma volume (PV). Exercise training can induce BV expansion: PV expansion usually occurs immediately, but EV expansion takes weeks. EV and PV expansion contribute to aerobic power improvements associated with exercise training. Repeated heat exposure induces PV expansion but does not alter EV. PV expansion does not improve thermoregulation, but EV expansion improves thermoregulation during exercise in the heat. Dehydration decreases PV (and increases plasma tonicity) which elevates heat strain and reduces exercise performance. High altitude exposure causes rapid (hours) plasma loss. During initial weeks at altitude, EV is unaffected, but a gradual expansion occurs with extended acclimatization. BV adjustments contribute, but are not key, to altitude acclimatization. Microgravity decreases PV and EV which contribute to orthostatic intolerance and decreased exercise capacity in astronauts. PV decreases may result from lower set points for total body water and central venous pressure, while EV decreases may result from increased erythrocyte destruction. Trauma, renal disease, and chronic diseases cause anemia from hemorrhage and immune activation which suppresses erythropoiesis. The re-establishment of EV is associated with healing, improved life quality, and exercise capabilities for these injured/sick persons.
Topics: Adaptation, Physiological; Altitude; Blood Volume; Body Temperature Regulation; Erythrocyte Volume; Exercise Tolerance; Heat Stress Disorders; Humans; Hypogravity; Physical Endurance
PubMed: 10694114
DOI: 10.1097/00005768-200002000-00012 -
Transfusion Science Sep 1997Adequate cardiac output and tissue perfusion is dependent on intravascular blood volume and its adequate return to the heart. Considering the overall functions of the... (Review)
Review
Adequate cardiac output and tissue perfusion is dependent on intravascular blood volume and its adequate return to the heart. Considering the overall functions of the cardiovascular system in ensuring appropriate flow to the peripheral microcirculation, it is not surprising that conflicts of interest may occur when an organism is exposed to stresses. Of particular importance are the stresses in which there are increased oxygen demands, decreased oxygen availability and concomitant requirements for thermoregulation. When there is depletion of intravascular blood volume, the splanchnic circulation is in effect an "autologous blood bank" for maintaining venous return until trans-capillary refill and haemodilution occurs. With the acute haematological stress response centralisation of blood, secondary contraction of the venous capacitance occurs, as seen with acute hypoxia. This results in overfilling of the heart, activation of atrial volume receptors, release of atrial natriuretic peptide and subsequent reduction of the plasma volume by rapid shifting of plasma into the lymphatic capacitance (via spleen) and transcapillary efflux throughout the circulation. In this overview the physiology and pathophysiology of blood volume, red cell mass and plasma volume regulation is reviewed.
Topics: Adaptation, Physiological; Atrial Natriuretic Factor; Blood Volume; Cardiac Output; Fluid Therapy; Hematocrit; Humans; Plasma Volume; Stress, Physiological
PubMed: 10175155
DOI: 10.1016/S0955-3886(97)00040-4