Exercise fitness, cardiac work and blood viscosity factors in patients and normals

A study of 41 cardiovascular patients and normals showed significant correlations between physical fitness (as expressed by a fitness index based on work output) and high shear rate blood viscosity (p less than 0.01); between the cardiac work expressed as double product (= myocardial oxygen demand) and aggregation of red cells (p less than 0.05); between the triple term of cardiac work (fitness index divided by double product) and high shear rate blood viscosity (p less than 0.005) or aggregation of red cells (p less than 0.05), in all cases correlations being negative i.e., higher cardiac work or higher fitness being related to low blood viscosity or lower aggregation of red cells. Significant differences were found between high-fitness and low-fitness groups, the high-fitness group showing from plasma viscosity (p less than 0.0005), lower fibrinogen level (p less than 0.05), and higher albumin/fibrinogen ratio (p less than 0.01).     

Correction of erythrocyte shape abnormalities in familial hypercholesterolemia after LDL-apheresis: does it influence cerebral hemodynamics?

It is well known that red blood cells incubated in low-density lipoprotein (LDL)-rich medium show shape abnormalities that revert to normal after reincubation in normal plasma. Patients with homozygous familial hypercholesterolemia (HFH) have an increased percentage of abnormally-shaped erythrocytes (mostly stomatocytes, knisocytes, and crenated cells) compared to normocholesterolemic controls: 7.73+/-0.96 versus 3.52+/-0.52 (mean+/-SEM; P = 0.001). To confirm the role of high LDL concentration in inducing red cell shape abnormalities we determined the percentage of abnormally shaped erythrocytes in seven HFH patients 1 day after the procedure of LDL-apheresis with a 40% cholesterol decrease. A reduction in kniscocytes, stomatocytes, and crenated cells was observed in the patients treated by LDL-apheresis (P < 0.01). To investigate the possible benefit of a reduction in erythrocyte shape abnormality on cerebral hemodynamics, cerebral flow velocity, as evaluated by transcranial Doppler, was evaluated concomitantly and found to be remarkably increased after apheresis (P < 0.01). No significant change in hematocrit, plasma viscosity, blood viscosity, mean pressure, or cardiac output was detected, 1 day after apheresis. An inverse correlation was demonstrated (r = 0.55; P = 0.04) between changes in the percentage of knisocytes+stomatocytes +crenated cells and percent changes in middle cerebral artery peak systolic velocity. The correction of erythrocyte shape abnormalities after LDL-apheresis might be related to dramatic changes in plasma phospholipid concentration and proportion occurring after this procedure in HFH patients. The reduction of erythrocyte shape abnormalities could contribute, together with other hemorheological factors, to the improvement of cerebral hemodynamics after LDL-apheresis.     

Evaluation of erythrocyte morphology as deformability index in patients suffering from vascular diseases, with or without diabetes mellitus: correlation with blood viscosity and intra-erythrocytic calcium

The aim of our study was to evaluate the erythrocytic morphology in vascular patients, with or without diabetes, showing cell alterations correlated to blood viscosity and intra-erythrocytic calcium. We studied 108 subjects: 20 normal subjects, 58 vascular patients (25 suffering from CHD, 19 from CVD, 14 from POAD) and 30 non-insulin-dependent diabetes patients with vascular disease in metabolic compensation (13 CHD, 9 CVD, 8 POAD). Erythrocytic morphology, blood viscosity and intra-erythrocytic calcium were evaluated. Our results show that bowls, the most deformable red cells, decreased significantly in vascular patients and in POAD diabetics, while the discocytes, having a stiffer form, greatly increased in subjects suffering from ischemic disease and in POAD diabetics. The altered red cells (echinocytes and knizocytes) reached a statistical significance in CVD and POAD diabetics. Comparing the percentage of discocytes to intraerythrocytic calcium content in vasculopathic subjects, we obtained a significant correlation. No evidence of a relationship between discocytes and blood viscosity was found, even if blood viscosity significantly increased in patients affected by ischemic disease. These results suggest that ischemia decreases the deformability of red cells which is supported by the study of red cells morphology, by the erythrocytic morphology index (EMI), which becomes < 1, and by the evaluation of cytosolic calcium content.     

Effect of chronic anemia on the endothelium-dependent dilatation of the brachial artery

The effect of changes in main determinants of whole blood viscosity after red blood cell transfusion on endethel dependent dilatation of brachial artery was studied in patients treated with transfusion because of symptoms of chronic anaemia. PATIENTS AND METHODS: 10 patients were involved, 8 females 2 males, mean age 50.9 +/- 16.6 years. Following blood tests were performed at hospital admission: hemoglobin, red blood cell count, heamatocrit, white blood cell count, platelet count, plasma total protein, fibrinogen, plasma viscosity, blood urea nitrogen, creatinine, cholesterol, triglicerides. Flow mediated dilatation of brachial artery was determined, too. Blood tests and flow mediated dilatation study were repeated after transfusion. RESULTS: The main determinants of whole blood viscosity increased after transfusion. The increase of hemoglobin, red blood cell count, hematocrit were highly significant. The central flow velocity in brachial artery decreased at rest and during hyperemia as well. The flow mediated dilatation of brachial artery wasn't significantly changed by transfusion. CONCLUSIONS: Change of determinants of whole blood viscosity caused by transfusion didn't change the flow mediated dilatation of brachial artery. The probable reason for this that the increase of whole blood viscosity in associated with the decrease of central flow velocity. These two counteracting changes probably equal each other.     

Conjugated estrogen reduces transfusion and coagulation factor requirements in orthotopic liver transplantation

We conducted a prospective, randomized study to determine the efficacy of conjugated estrogen in reducing blood product transfusion during orthotopic liver transplantation (OLT). Patients undergoing OLT were included in the study. Only those having a reaction time of more than 30 mm or 15 min (19 -28 mm) on computed thromboelastography (CTEG) at the beginning of surgery were enrolled in the study. Patients were randomized to receive either conjugated estrogen (CE) or placebo. Every patient received a first dose of CE (100 mg i.v.) (20 mL) or placebo (20 mL of isotonic sodium chloride solution) at the beginning of the procedure and a second dose of CE (100 mg i.v.) or 20 mL of placebo (20 mL of isotonic sodium chloride solution) just after reperfusion of the new graft. The two groups were similar in age, weight, requirement for veno-veno bypass, time on veno-veno bypass, CTEG measurement, and preoperative hemoglobin and platelet values. Blood products were given in relation to hematocrit and coagulation (CTEG) variables, which were measured every hour during the surgery. The amount of transfused blood products did not differ in terms of units of cryoprecipitate, but the intraoperative requirements for red blood cells (6 +/- 3 vs 9 +/- 6 U; P = 0.05), platelets (12 +/- 8 U vs 18 +/- 10 U; P = 0.05) and fresh-frozen plasma (3 +/- 3 U vs 6 +/- 4 U; P = 0.001) was significantly less in the estrogen group than in the control group. We conclude that CE is associated with a significant decrease in use of fresh-frozen plasma, platelets, and red blood cells during OLT. Implications: In this study, we prospectively investigated whether i.v. conjugated estrogen could decrease blood product transfusion during orthotopic liver transplantation. Conjugated estrogen-treated patients received less fresh-frozen plasma, red blood cells, and platelets. In this population of patients, conjugated estrogen can be a useful addition in coagulation management during orthotopic liver transplantation.     

The hemorheologic effects of hand-transmitted vibration

Vibration white finger (VWF) is an ischemic condition of the hands that is associated with long-term exposure to hand-held vibration tools. The pathophysiology of VWF remains unknown. The aim of this study was to assess the hemorheologic effect of acute hand-transmitted vibration. This study investigated 52 men divided into two groups: VWF = 29, mean age 46.9 years (range twenty-two to sixty-six); Controls = 23, mean age 42.8 years (range twenty to sixty-four). Each subject gripped a vibrating handle for seven minutes thirty seconds at a vibration frequency of 120 Hz with an amplitude of displacement of 0.25 mm. Venous blood was analyzed before and after acute vibration to determine the hematocrit, the plasma hemoglobin concentration, plasma viscosity, and red cell deformability, expressed as red cell transit time (RCTT). At rest, there was no significant difference in RCTT, plasma viscosity, hematocrit, and plasma hemoglobin concentration between the VWF group and controls. Acute vibration did, however, significantly increase the red cell transit time in the VWF group but not in the control group. In both groups vibration resulted in a significant increase in plasma viscosity, hematocrit, and plasma hemoglobin concentration in hand venous blood. Moreover, in each group there was a highly significant correlation between the change in plasma viscosity and the change in the hemoglobin concentration and the hematocrit. The authors conclude that hand-transmitted vibration is associated with hemoconcentration.     

Sialic acid-depleted red cells following acute myocardial infarction

A reduction of red cell SA in patients following acute myocardial infarction is reported and the effects of SA-depleted red cells on cardiac index and alveolar capillary blood flow in the dog are described. The mean red cell SA in 26 patients following acute myocardial infarction was 0.021 +/- 0.001 compared with a mean of 0.031 +/- 0.002 mumol./0.1 ml RBC in 12 normal subjects (p less than 0.01). In five dogs injected with neuraminidase, an enzyme which removes SA from the red cell membrane, a 43% decrease in mean cardiac index from 2.3 +/- 0.22 to 1.3 +/- 0.16 (p less than 0.01) occurred. In films of the pulmonary microcircuation the mean widths of typical alveolar capillary beds decreased 42.6% +/- 5% (p less than 0.01). In three other dogs, autotransfusion with SA-depleted stored blood resulted in a 25% decrease in mean cardiac index from 2.0 +/- 0.21 to 1.5 +/- 0.21 (p less than 0.2), and a 21.7% +/- 0.9% (p less than 0.01) decrease in mean widths of typical alveolar capillary beds. We conclude that a reduction of red cell SA follows acute myocardial infarction and that SA-depleted red cells decrease cardiac index and alveolar capillary blood flow in the dogs.     

Whole blood viscosity and haematocrit are associated with internal carotid atherosclerosis in men

BACKGROUND: Alterations in blood viscosity and haematocrit have been described in patients with coronary and cerebrovascular diseases. The results have not been conclusive, as modifications of these parameters are often associated with the presence of coronary heart disease (CHD) risk factors. The aim of this study was to verify whether blood viscosity and haematocrit are increased in patients with carotid atherosclerosis, independently of the presence of CHD risk factors. METHODS: Male patients with internal carotid atherosclerosis (ICA+, n = 28) were selected from participants in a cardiovascular disease prevention campaign. Controls (ICA-, n = 28), also participating in the prevention campaign, were matched for age and all the classical CHD risk factors. Plasma lipids, glucose and fibrinogen were determined by routine methods. Cigarette smoking and current drug therapy was established by questionnaire. Whole blood viscosity was measured at shear rates of 450 and 225/s, using a cone-plate viscometer. Echo-Doppler of carotid arteries was performed with an ATL Ultramark 9 HDI using a 5-10 MHz multifrequency probe. RESULTS: Blood pressure, plasma lipids, glucose, body mass index, fibrinogen and plasma viscosity were similar in the two groups. ICA+ patients, compared with the ICA- group, had significantly greater values of blood viscosity (4.52 +/- 0.37 cP compared with 4.18 +/- 0.45 cP, P < 0.005 respectively; shear rate 450/s) and haematocrit (48.57 +/- 3.19% compared with 45.57 +/- 4.81%, P < 0.008 respectively). CONCLUSIONS: Our findings demonstrate that blood viscosity and haematocrit are increased in men with internal carotid atherosclerosis, independently of the presence of risk factors for atherosclerosis.     

The biochemical and clinical aspects of the participation of granulocytes and their proteinases in a vascular wall lesion

Some components of plasma and granulocyte proteolytic system, granulocyte activation degree were evaluated in 15 patients with nonspecific aortic arteritis (NAA) and 12 hereditary hypercholesterolemia (HHC) patients. Catepsin G activity in blood plasma of NAA and HHC patients was higher than in donors 8-9 and 6-fold, respectively (p < 0.001). Granulocyte collagenase activity, spontaneous NBT test values in them were higher than in donors 6 and 4-fold (p < 0.02 and p < 0.01, respectively), 2-fold (p < 0.005 and p < 0.001, respectively). The data obtained confirm the suggestion on the presence of an inflammatory component not only in pathogenesis of NAA, but also in HHC causation.     

Relation of endothelium, thrombogenesis, and hemorheology in systemic hypertension to ethnicity and left ventricular hypertrophy

Although the arterial tree is exposed to increased pressure in hypertensive patients, paradoxically, the complications of hypertension (heart attacks, stroke) are mainly thrombotic rather than hemorrhagic. Patients with left ventricular (LV) hypertrophy are at high risk of the complications of hypertension. We performed a cross-sectional study of 178 patients attending a hypertension clinic in a city center teaching hospital, and measured plasma levels of the soluble adhesion molecule P-selectin (associated with platelet activity/function and atherosclerosis), the von Willebrand factor (vWf; a marker of endothelial dysfunction), fibrin D-dimer (an index of thrombogenesis), plasminogen activator inhibitor (PAI, an index of fibrinolysis), lipoprotein(a) (Lp(a), associated with thrombogenesis and atherogenesis) and hemorheological indexes (fibrinogen, hematocrit, plasma viscosity, hemoglobin) in patients with essential hypertension, in whom the LV mass and LV mass index were determined using echocardiography. The 178 patients (86 men, mean age 54 +/- 15 years) were compared with 47 normotensive healthy controls (aged 56 +/- 20 years). Hypertensive patients had higher P-selectin, PAI, vWf, fibrin D-dimer, Lp(a), plasma fibrinogen, and plasma viscosity when compared with controls. Black hypertensive patients had higher Lp(a) levels and LV septal and posterior wall thickness on echocardiography, but lower plasma PAI levels. Patients with LV hypertrophy (defined as a LV mass index > 134 g/m2 in men or > 110 g/m2 in women) had higher plasma fibrinogen compared with those without LV hypertrophy. Systolic blood pressures were significantly correlated to age, plasma viscosity, plasma fibrinogen, and vWf. Diastolic blood pressures were significantly correlated with age and plasma fibrinogen. Fibrinogen levels were correlated with LV mass, LV mass index, left atrial size, plasma viscosity, and vWf. Fibrin D-dimer levels were significantly correlated with vWf and fibrinogen levels. Thus, hypertensive patients have high plasma fibrinogen levels, thrombogenesis, and impaired fibrinolysis (as indicated by high D-dimer and PAI levels, respectively), platelet activation (raised soluble P-selectin), and endothelial dysfunction (high vWF). The high plasma fibrinogen levels were related to blood pressures, LV mass index (and LV hypertrophy), and left atrial size. These abnormalities in hemorheologic factors and markers of thrombogenesis and endothelial function may act synergistically to increase the risk of thrombogenesis and atherosclerosis in hypertensive patients.     

Effect of dextroamphetamine and methylphenidate on calcium and magnesium concentration in hyperactive boys

Levels of calcium in plasma, red blood cells, and mononuclear blood cells, levels of calcium in plasma, and the plasma calcium-to-magnesium ratio were measured at baseline and after 3 weeks of each drug phase of a double-blind, placebo-controlled study of methylphenidate and dextroamphetamine in hyperactive boys. Levels of magnesium in plasma were significantly higher after 3 weeks of dextroamphetamine treatment, and the calcium-to-magnesium ratio was significantly lower after 3 weeks of either drug compared with the baseline or placebo condition. There was no change in magnesium levels in red blood cells or mononuclear blood cells. These measures were obtained 30 minutes before the morning dose and at 9 a.m., 9:30 a.m., 10:30 a.m., 11:00 a.m., and noon on the last day of each 3-week phase. Analysis of variance revealed a drug effect on plasma magnesium and on the calcium-to-magnesium ratio but no drug x time interaction. Although these changes were not correlated with the time course of acute symptomatic response to stimulant therapy, the decrease in the ratio may be relevant to side effects and treatment resistance associated with stimulant use.     

The effect of Leboyer delivery on blood viscosity and other hemorheologic parameters in term neonates

OBJECTIVE: This study was done to compare postnatal alterations in blood viscosity, hematocrit value, plasma viscosity, red blood cell aggregation, and red blood cell deformability in term neonates undergoing both early umbilical cord clamping and delivery according to the Leboyer method. STUDY DESIGN: The umbilical cords of 15 healthy, term infants were clamped within 10 seconds of birth (early cord clamping), and 15 infants delivered according to the Leboyer method were placed on the mother's abdomen, and the umbilical cords were clamped 3 minutes after birth. Hemorheologic parameters were studied in umbilical cord blood at 2 hours, 24 hours, and 5 days from the time of delivery. RESULTS: The residual fetal placental blood volume decreased from 45 +/- 8 ml/kg (x +/- SD) after early cord clamping to 25 +/- 5 ml/kg after delivery by the Leboyer method. After Leboyer-method delivery, the hematocrit value rose from 48% +/- 5% at birth to 58% +/- 6% 2 hours after delivery, 56% +/- 7% at 24 hours, and 54% +/- 8% after 5 days. Blood viscosity in the Leboyer-method group increased by 32% within the first 2 hours but did not change significantly during the following 5 days. Plasma viscosity, red blood cell aggregation, and red blood cell deformability were not affected by the mode of cord clamping. CONCLUSIONS: Delivery by the Leboyer method leads to a significant increase in blood viscosity as a result of increasing hematocrit value, whereas other hemorheologic parameters are similar to those of infants with early cord clamping.     

Peripheral blood levels of progesterone and 11-hydroxycortico-steroids and serum protein pattern in cows with clinical ovarian dysfunction

This study was undertaken to determine T3 content in red cells by radioimmunoassay. T3 in red blood cells was solubilized fairly from the stroma by hemolysis and red-cell T3 content could be determined directly by radioimmunoassay of the lysate. After hemolysing red cells with an equal volume of distilled water, 0.4 ml of the hemolyzate was used for the assay. The red-cell T3 content was expressed as ng/ml of red-cell volume. The normal T3 range in red cells was 0.20-0.45 ng/ml, and the Mean+/-SD was 0.32+/-0.10 ng/ml. The limit of detectability was 0.2 ng/ml. In hyperthyroid patients, the red-cell T3 content was more than 0.50 ng/ml with a Mean +/-SD of 1.35+/-0.65 ng/ml. In hypothyroid patients, red cells contained less than 0.25 ng/ml of T3, and there was an overlap from 0.20 to 0.25 ng/ml in the content of red-cell T3 in hypothyroid and euthyroid subjects. The patients with T3 toxicosis showed a high or normal level of red-cell T3. A positive correlation was noted between the red-cell T3 content and the serum T3 level (r=0.66). The correlation between the red-cell T3 content and the free T4 index (expressed as T7) was also positive (r=0.67). From these experiments, it is suggested that the red-cell T3 is low in comparison with the serum T3 levels, and depends on two factors; serum T4 and serum T3 levels.     

Retinal detachments due to traumatic tears in the pars plana ciliaris

Hypothermia during orthotopic liver transplantation (OLT) is common despite measures to prevent this complication. We retrospectively analyzed two groups of patients; those managed with (n = 113) or without (n = 109) a heat exchanger (HE) incorporated in the venovenous bypass (VVB) circuit to test the hypothesis that normothermia before liver reperfusion minimizes hypotension during reperfusion and decreases neohepatic transfusion requirements. Use of the HE resulted in significantly warmer patients during reperfusion and at the end of surgery (P < .001). An increase in neohepatic transfusion requirement was observed in patients with HE use: packed red blood cells, 4 +/- 4 versus 3 +/- 3 units; fresh-frozen plasma, 5 +/- 5 versus 4 +/- 4 units; platelets, 8 +/- 8 versus 6 +/- 7 units; and cryoprecipitate, 5 +/- 7 versus 3 +/- 5 units. There was no difference between the two groups in the untoward hemodynamic events during reperfusion of the liver (P = .31). We conclude that during OLT, the use of an HE in a nonheparinized VVB circuit helps maintain normothermia. Our limited experience suggests that its use is safe but does not improve hemodynamic stability during reperfusion or decrease blood loss during the neohepatic period.     

Red blood cell glutathione and plasma sulfhydryls in chronic lung disease of the newborn

We compared the postnatal changes (days 1-28) in red blood cell glutathione and plasma sulfhydryl content in preterm babies developing chronic lung disease (CLD, n = 13) to those in babies with respiratory distress syndrome (RDS, n = 13) and control babies (n = 21). There were no initial differences in these measurements between the three groups. However, on day 28 in CLD and RDS the red blood cell glutathione was decreased compared to the control babies (p < 0.05). In CLD, there was a significant correlation between reduced/oxidized glutathione and (i) maximal FiO2 (r = -0.69, p < 0.05) and (ii) minimal a/A ratio (r = +0.73, p < 0.005). On day 28, although the plasma sulfhydryl level did not differ between the groups, the sulfhydryl/total protein ratio was decreased in CLD (p < 0.05). The late decrease in both glutathione and sulfhydryl/total protein ratio in babies with CLD suggests that oxidative stress is still ongoing at 28 days after birth and that the antioxidant capacity of their blood is still diminished at this time.     

Renovascular adaptive changes in chronic hypoxic polycythemia

BACKGROUND: Chronic hypoxia in rats produces polycythemia, and the plasma fraction falls, reducing renal plasma flow (RPF) relative to renal blood flow (RBF). Polycythemia also causes increased blood viscosity, which tends to reduce RBF and renal oxygen delivery. We studied how renal regulation of electrolyte balance and renal tissue oxygenation (which is crucial for erythropoietin regulation) are maintained in rats during hypoxic exposure. METHODS: Rats of two strains with differing polycythemic responses, with surgically implanted catheters in the urinary bladder, femoral artery, and left renal and right external jugular veins, were exposed to a simulated high altitude (0.5 atm) for 0, 1, 3, 14, and 30 days, after which RPF (para-aminohippurate clearance), glomerular filtration rate (GFR, polyfructosan clearance), hematocrit and blood gases were measured, and RBF, renal vascular resistance and hindrance (resistance/viscosity), renal oxygen delivery, and renal oxygen consumption were calculated. RESULTS: During chronic hypoxia RBF increased, but RPF decreased because of the polycythemia. GFR remained normal because the filtration fraction (FF) increased. Renal vascular resistance decreased, and renal vascular hindrance decreased more markedly. Renal oxygen delivery and consumption both increased. CONCLUSIONS: During chronic hypoxia GFR homeostasis apparently took precedence over RBF autoregulation. The large decrease in renal vascular hindrance suggested that renal vascular remodeling contributes to GFR regulation. The reduced hindrance also prevented a vicious cycle of increasing polycythemia and blood viscosity, decreasing RBF, and increasing renal hypoxia and erythropoietin release.     

Responses of the red blood cells from two high-energy-demand teleosts, yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis), to catecholamines

In fishes, catecholamines increase red blood cell intracellular pH through stimulation of a sodium/proton (Na+/H+) antiporter. This response can counteract potential reductions in blood O2 carrying capacity (due to Bohr and Root effects) when plasma pH and intracellular pH decrease during hypoxia, hypercapnia, or following exhaustive exercise. Tuna physiology and behavior dictate exceptionally high rates of O2 delivery to the tissues often under adverse conditions, but especially during recovery from exhaustive exercise when plasma pH may be reduced by as much as 0.4 pH units. We hypothesize that blood O2 transport during periods of metabolic acidosis could be especially critical in tunas and the response of rbc to catecholamines elevated to an extreme. We therefore investigated the in vitro response of red blood cells from yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis) to catecholamines. Tuna red blood cells had a typical response to catecholamines, indicated by a rapid decrease in plasma pH. Amiloride reduced the response, whereas 4,4'diisothiocyanatostilbene-2,2'-disulphonic acid enhanced both the decrease in plasma pH and the increase in intracellular pH. Changes in plasma [Na+], [Cl-], and [K+] were consistent with the hypothesis that tuna red blood cells have a Na+/H+ antiporter similar to that described for other teleost red blood cells. Red blood cells from both tuna species were more responsive to noradrenaline than adrenaline. At identical catecholamine concentrations, the decrease in plasma pH was greater in skipjack tuna blood, the more active of the two tuna species. Based on changes in plasma pH, the response of red blood cells to catecholamines from both tuna species was less than that of rainbow trout (Oncorhynchus mykiss) red blood cells, but greater than that of cod (Gadus morhua) red blood cells. Noradrenaline had no measurable influence on the O2 affinity of skipjack tuna blood and only slightly increased the O2 affinity of yellowfin tuna blood. Our results, therefore, do not support our original hypothesis. The catecholamine response of red blood cells from high-energy-demand teleosts (i.e., tunas) is not enhanced compared to other teleosts. There are data on changes in cardio-respiratory function in tunas caused by acute hypoxia and modest increases in activity, but there are no data on the changes in cardio-respiratory function in tunas accompanying the large increases in metabolic rate seen during recovery from exhaustive exercise. However, we conclude that during those instances where high rates of O2 delivery to the tissues are needed, tunas' ability to increase cardiac output, ventilation volume, blood O2 carrying capacity, and effective respiratory (i.e., gill) surface area are probably more important than are the responses of red blood cells to catecholamines. We also use our data to investigate the extent of the Haldane effect and its relationship to blood O2 and CO2 transport in yellowfin tuna. Yellowfin tuna blood shows a large Haldane effect; intracellular pH increases 0.20 units during oxygenation. The largest change in intracellular pH occurs between 40-100% O2 saturation, indicating that yellowfin tuna, like other teleosts, fully exploit the Haldane effect over the normal physiological range of blood O2 saturation.     

Bovine haemoglobin is more potent than autologous red blood cells in restoring muscular tissue oxygenation after profound isovolaemic haemodilution in dogs

PURPOSE: This study compares the effects of stored red cells, freshly donated blood and ultrapurified polymerized bovine haemoglobin (HBOC) on haemodynamic variables, oxygen transport capacity and muscular tissue oxygenation after acute and almost complete isovolaemic haemodilution in a canine model. METHODS: Following randomization to one of three groups, 24 anaesthetized Foxhounds underwent isovolaemic haemodilution with 6% hetastarch to haematocrit levels of 20%, 15% and 10% before they received isovolaemic stepwise augmentation of 1 g.dl-1 haemoglobin. In Group 1, animals were given autologous stored red cells which they had donated three weeks before. In Group 2, animals received freshly donated blood harvested during haemodilution. In Group 3, animals were infused with HBOC. Skeletal muscle tissue oxygen tension was measured with a polarographic 12 mu needle probe. RESULTS: In all groups, heart rate and cardiac index were increased with decreasing vascular resistance during haemodilution (P < 0.05). Haemodynamic variables showed a reversed trend during transfusion when compared to haemodilution but remained below baseline (P < 0.05). Arterial and venous oxygen content were changed in parallel to changes of haematocrit and haemoglobin concentrations but were lower in Group 3 than in Groups 1 and 2 (P < 0.05) during transfusion. In contrast, the oxygen extraction ratio was higher in Group 3 (59 +/- 8%, P < 0.01) at the end of transfusion than in Group 1 (37 +/- 13%) and 2 (32 +/- 5%). In Group 3, mean tissue oxygen tension increased from 16 +/- 5 mmHg after haemodilution to 56 +/- 11 mmHg after transfusion (P < 0.01) and was higher than in Group 1 (41 +/- 9, P < 0.01) and Group 2 (29 +/- 11, P < 0.01). While in Group 3 an augmentation of 0.7 g.dl-1 haemoglobin resulted in restoring baseline tissue oxygenation, higher doses of 2.7 g.dl-1 and 2.1 g.dl-1 were needed in Groups 1 and 2 to reach this level (P < 0.01). CONCLUSION: The results show a higher oxygenation potential of HBOC than with autologous stored red cells because of a more pronounced oxygen extraction.     

Blood volume determination with sodium fluorescein and radioactive chromium--a clinical comparison of methods

OBJECTIVE: There exists no method so far for the determination of circulating blood volume as an important parameter of circulatory function widely usable under clinical conditions. Therefore, the present study was designed to investigate whether identical distribution spaces could be measured by two methods for blood volume determination using sodium fluorescein (SoF) and radioactively labelled red blood cells (51Cr*). DESIGN: Comparative study. SETTING: Operating theatre, recovery room, or intensive care unit of a university hospital. PATIENTS: 35 patients undergoing abdominal, urological or vascular surgery. INTERVENTIONS: Simultaneous determinations of blood volume using SoF and 51Cr* in the intra- and postoperative period. RESULTS: There were no significant differences between the calculated means of blood volume (4,445 vs. 4,407 ml), red cell volume (1,554 vs. 1,540 ml), and plasma volume (2,891 vs. 2,807 ml) for 51Cr*-vs. SoF-stained red blood cells. The coefficient of correlation between the two methods was r = 0.95. The mean percentage error was -0.6% between the two methods, the precision 5.6%. CONCLUSIONS: SoF-stained erythrocytes allow a determination of the same distribution space as the well-established radioactive method using 51Cr*. Therefore, SoF-staining may replace 51Cr* labelling of red blood cells for the determination of blood volume in patients.