REGIONAL BLOOD FLOW IN NORMOVOLAEMIC AND HYPOVOLAEMIC HAEMODILUTION: An experimental study

Rosberg, B.; Wulff, Krister

doi:10.1093/bja/51.5.423

Cited by 35 publications

(17 citation statements)

References 29 publications

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“…3). The latter is probably due to the reversal of the hyperhemodynamic state provoked by the anemia (23,24). The fall in leg partially offset the increase in O 2 delivery expected from the rise in arterial O 2 content.…”

Section: Discussionmentioning

confidence: 96%

Effects of erythropoietin on muscle O2 transport during exercise in patients with chronic renal failure.

Marrades

Roca²,

Campistol³

et al. 1996

J. Clin. Invest.

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Erythropoietin (rHuEPO) has proven to be effective in the treatment of anemia of chronic renal failure (CRF). Despite improving the quality of life, peak oxygen uptake after rHuEPO therapy is not improved as much as the increase in hemoglobin concentration ([Hb]) would predict. We hypothesized that this discrepancy is due to failure of O 2 transport rates to rise in a manner proportional to [Hb]. To test this, eight patients with CRF undergoing regular hemodialysis were studied pre-and post-rHuEPO ([Hb] ϭ 7.5 Ϯ 1.0 vs. 12.5 Ϯ 1.0 g · dl Ϫ 1 ) using a standard incremental cycle exercise protocol. A group of 12 healthy sedentary subjects of similar age and anthropometric characteristics served as controls. Arterial and femoral venous blood gas data were obtained and coupled with simultaneous measurements of femoral venous blood flow ( leg) by thermodilution to obtain O 2 delivery and oxygen uptake ( O 2 ). Despite a 69% increase in [Hb], peak O 2 increased by only 33%. This could be explained largely by reduced peak leg blood flow, limiting the gain in O 2 delivery to 37%. At peak O 2 , after rHuEPO, O 2 supply limitation of maximal O 2 was found to occur, permitting the calculation of a value for muscle O 2 conductance from capillary to mitochondria (DO 2 ). While DO 2 was slightly improved after rHuEPO, it was only 67% of that of sedentary control subjects. This kept maximal oxygen extraction at only 70%. Two important conclusions can be reached from this study. First, the increase in

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Section: Discussionmentioning

confidence: 96%

Effects of erythropoietin on muscle O2 transport during exercise in patients with chronic renal failure.

Marrades

Roca²,

Campistol³

et al. 1996

J. Clin. Invest.

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“…The effects of both isovolemic hemodilution (1 7, 20, 2 1) and chronic anemia ( 1 3, 30) on GI blood flow have been studied using adult dogs. Isovolemic hemodilution (decrease in hematocrit by 20-35%) resulted in a decrease in mesenteric vascular resistance and an increase in GI blood flow (17,20,21). Chronic anemia induced by repeated phlebotomy caused no change in mesenteric blood flow when hematocrit was reduced by 30% (13, 30).…”

Section: Discussionmentioning

confidence: 99%

“…Because the neutral thermal range (21) seems to coincide with the conditions under which premature babies show the greatest survival rate (4, 7), it has been theorized that the best incubator or warmer would be one which maintained the infant in a neutral thermal environment: a state of minimal oxygen consumption.…”

Section: Discussionmentioning

confidence: 99%

“…The compensatory response of the GI tract to hypoxemia has been evaluated in adult animals. Anemic hypoxemia resulted in decreased mesenteric vascular resistance and increased mesenteric blood flow in canine (20,21,30) and feline (1 7) species. O2 extraction by the gut was unchanged; therefore, under these conditions, GI O2 consumption was maintained by regulating O2 delivery (1 7).…”

Section: Abbreviationsmentioning

confidence: 99%

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Gastrointestinal Blood Flow and Oxygen Consumption in the Newborn Lamb: Effect of Chronic Anemia and Acute Hypoxia

Nowicki

Hansen

et al. 1984

Pediatr Res

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SummaryThe purpose of this study was to investigate the compensatory change in circulation and oxygenation of the newborn lamb gastrointestinal (GI) tract in response to anemic and hypoxic hypoxemia. Radiolabeled microspheres were used to measure blood flow. We subjected the newborn lamb to a 30-35% reduction in hematocrit 4 d before study and to a 10% oxygen environment for 30 min during the study to induce chronic anemic and acute hypoxic hypoxemia, respectively. The circulatory and oxygenation responses were measured 1 h after a standard milk feeding in all cases. During the experimental periods, no change in total GI blood flow was observed. Because of a failure to augment blood flow during hypoxemia, 0 2 delivery to the GI tract decreased significantly. Despite this, GI 0, consumption was not compromised because tissue O2 extraction by the GI tract rose significantly. The response of the newborn lamb GI tract to hypoxemia after feeding is augmentation of O2 extraction. The newborn's GI tract did not regulate local GI blood flow. AbbreviationsCaOz, arterial oxygen content D02GI, oxygen delivery to gastrointestinal tract GI, gastrointestinal LV, left ventricle PV, portal vein QGI, total gastrointestinal blood flow V02GI, oxygen consumption by gastrointestinal tract Hypoxemia can result from a decreased hemoglobin mass or diminished percentage saturation of hemoglobin. In each instance, hypoxemia will compromise tissue oxygenation unless adequate compensation occurs. The process of compensation can be mediated by increasing blood flow or tissue oxygen extraction. The compensatory response of the GI tract to hypoxemia has been evaluated in adult animals. Anemic hypoxemia resulted in decreased mesenteric vascular resistance and increased mesenteric blood flow in canine (20,21,30) and feline (1 7) species. O2 extraction by the gut was unchanged; therefore, under these conditions, GI O2 consumption was maintained by regulating O2 delivery (1 7). In response to hypoxic hypoxemia, denervated dog small intestine demonstrated the capacity to increase local blood flow (l,23) and enhance 0 2 extraction (23).The response of the newborn GI tract to hypoxemia has not been thoroughly investigated; however, previous work in the lamb suggests that the newborn's response to decreased 0 1 availability might differ from that of the adult. The lamb maintains a higher resting O2 consumption than mature sheep, which is affected by a high resting blood flow and low Or extraction (7). When the oxidative demands of the lamb gut are increased by feeding, only a limited mesenteric hyperemia results whereas a significant and sustained rise in 0 2 extraction occurs (8). This response is unlike that found after feeding in adult animals, where large increases in mesenteric blood flow are observed (3, 5,27).The purpose of this study was to investigate the compensatory changes occurring in the circulation and oxygenation of the newborn lamb GI tract in response to anemic or hypoxic hypoxemia. The response of the lamb GI tract was determined a...

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“…Decreased blood viscosity has been proposed as the principal mechanism for the increased cardiac output and decreased systemic vascular resistance during isovolemic hemodilution (Murray et al 1969). However, there are several evidences against this possibility: 1) the discrepancy between the very small decrease in viscosity and the important increment in GMBF observed in our experimental model; 2) the existence of a myogenic reflex counteracting the effects of low viscosity decreasing vascular resistance, specially in non-vital organs (Dintenfass 1971), 3) the different changes in regional blood flows described during acute or chronic normovolaemic anaemia despite the decline in viscosity in the whole circulating blood (Rosberg et al 1979), and 4) the finding that iso-viscous solutions used for blood replacement do not fully restore the low systemic vascular resistance induced by acute anaemia (Fowler and Holmes 1975). In addition, new evidences against a major role for the decreased blood viscosity on the vasodilatory state associated to anemia, has arised from recent studies demonstrating that haemodilution with oxyhemoglobin does not produce the hyperdynamic circulation despite a marked reduction in blood viscosity (Anand and Chandrashekar 1993).…”

Section: Discussionmentioning

confidence: 77%

Acute normovolaemic anaemia prevents ethanol-induced gastric damage in rats through a blood flow related mechanism

Casadevall

Piqué

Cirera

et al. 1994

Naunyn-Schmiedeberg's Arch Pharmacol

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The aim of the study was to assess whether changes in gastric mucosal blood flow induced by acute normovolaemic anaemia influence the susceptibility of the gastric mucosa to ethanol-induced damage, and the relationship of these changes with nitric oxide biosynthesis. Acute normovolaemic anaemia, promoted by exchanging 3 ml of blood by a plasma expander, induced a significant increase in gastric mucosal blood flow measured by hydrogen gas clearance, without changes in arterial blood pressure. After intragastric 60°7o ethanol administration, gastric blood flow was still significantly higher in anaemic than in control rats, and this was associated with a lower macroscopic and microscopic gastric damage. Following ethanol administration, anaemic rats pretreated with an inhibitor of nitric oxide biosynthesis (L-NMMA, 50 mg/kg, i.v.) had a lower gastric blood flow and a higher macroscopic gastric damage than anaemic rats without pretreatment. Anaemic rats pretreated with vasopressin also had after ethanol administration a lower gastric blood flow and a higher macroscopic gastric damage. It is concluded that acute normovolaemic anaemia protects the gastric mucosa against damage induced by intragastric ethanol. The inhibition of nitric oxide biosynthesis reverts in part this protective effect, and this seems to be related with the capability of nitric oxide to increase gastric mucosal blood flow, since vasoconstriction by a nitric oxide-independent mechanism causes a similar effect.

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REGIONAL BLOOD FLOW IN NORMOVOLAEMIC AND HYPOVOLAEMIC HAEMODILUTION: An experimental study

Cited by 35 publications

References 29 publications

Effects of erythropoietin on muscle O2 transport during exercise in patients with chronic renal failure.

Effects of erythropoietin on muscle O2 transport during exercise in patients with chronic renal failure.

Gastrointestinal Blood Flow and Oxygen Consumption in the Newborn Lamb: Effect of Chronic Anemia and Acute Hypoxia

Acute normovolaemic anaemia prevents ethanol-induced gastric damage in rats through a blood flow related mechanism

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