Decrease In Hct Research Articles

Idiopathic hemorrhagic vasculopathy syndrome in seven black rhinoceros.

Idiopathic hemorrhagic vasculopathy syndrome (IHVS) was diagnosed in 7 black rhinoceros; this newly described syndrome is characterized by severe body swelling in conjunction with a rapid and profound decrease in Hct. The disorder may be acute or chronic, may recur, and is potentially fatal. Five of the rhinoceros survived an initial episode of IHVS, and 2 of these 5 survived a recurrent episode of IHVS. Two rhinoceros died during treatment of IHVS. Treatment protocols varied, but all 7 rhinoceros received broad-spectrum antibiotics, because an infectious cause was suspected. All rhinoceros also received nonsteroidal antiinflammatory drugs and supportive care. Idiopathic hemorrhagic vasculopathy syndrome has many similarities to other vasculopathies of domestic animals, such as equine purpura hemorrhagica, but it also appears to have unique identifying features. It has been hypothesized that IHVS may be an immune response to an as yet unidentified infectious agent. Thorough and extensive testing has not identified the potential causative agent, nor the factors that predispose some black rhinoceros to developing IHVS. Further research into the rhinoceros immune system is ongoing and should help elucidate the mechanisms through which IHVS develops.

Effect of X-Ray Contrast Media on Blood Flow Properties after Coronary Angiography

In vitro studies suggest that ionic and nonionic X-ray contrast media have different effects on rheological parameters. The risk of thrombotic complications in coronary interventions was reported to be lower using ionic contrast media. The aim of the present study was to compare the effects of different types of contrast media on rheological parameters after coronary angiography. Sixty patients were randomized to four groups: ioxaglate 320 (dimeric, ionic, n=18), iomeprol 400 (monomeric, nonionic, n=12), iobitridol 350 (monomeric, nonionic, n=12), and iodixanol 320 (dimeric, nonionic, n=18). Blood samples were collected via the side port of the arterial sheath immediately before and at the end of coronary angiography. In our study, all types of contrast media caused a significant decrease in haematocrit (Hct), plasma viscosity (PV), erythrocyte aggregation (EA), and in the platelet reactivity index (PRI). The most pronounced decrease in Hct was found using the ionic dimer ioxaglate. There were no significant differences between the contrast media with respect to their effects on PV, EA, and PRI.

Percutaneous renal biopsy in the 1990s: Safety, value, and implications for early hospital discharge

To determine the parameters associated with significant bleeding and to examine the value of performing a renal biopsy, we studied 83 consecutive patients, including 24 renal allograft recipients, who had undergone percutaneous renal biopsy. The patients were stratified into four groups according to the percentage of decline in their hematocrit (Hct) at 24 hours postbiopsy, as follows: 10% or greater (n = 21; 25%) and less than 10% decline (n = 62; 75%). The latter group was further subgrouped into 5% to 10% (n = 22) and less than 5% decline (n = 40). There was a significant decline in Hct postbiopsy, with a linear correlation between the decrease in Hct at 6 and 24 hours (R2 = 0.47; P < 0.0001), suggesting that the former was a predictor of the latter. There was a linear correlation between the number of passes and number of cores obtained for the first four passes, but an inverse correlation when five passes or greater were required. Interestingly, there was no correlation between bleeding (>10% decline in Hct) and the number of passes or cores obtained. Gross hematuria and blood transfusion requirement were each encountered in three patients (3.6%). Importantly, the prebiopsy clinical diagnosis was altered in 18 of 59 native kidney biopsies (33%) and 10 of 24 transplant biopsies (41%). We conclude that percutaneous renal biopsy using an automated spring-loaded gun device coupled with ultrasound guidance is a safe technique and provides essential clinical information. Importantly, patients with a stable Hct at 6 hours were at low risk for bleeding at 24 hours while hospitalized. It remains to be determined if these findings could be extrapolated to early discharge from hospital.

RESTING HEMATOCRIT IN MALE CYCLISTS DURING A 6-DAY STAGE RACE

1623 The Union Cycliste International (UCI) currently prevents professional cyclists from competing if resting hematocrit (Hct) exceeds 50%. The aim of this study was to examine the effects of a 6-day stage race on resting Hct in a group of Australia's top male road cyclists. Body mass was measured and venous blood was collected (supine posture) on 6 consecutive mornings (D1-D6) from 14 cyclists (23.1±4.0 yrs; 71.3±5.5 kg) who raced 730 km in 6 days (5 road races, 1 criterium and 1 time-trial). Hct (spun capillary tubes) and hemoglobin (Hb) (Hemocue™) were measured in triplicate within 1 hr of blood collection (CV<3%). Plasma volume (PV) shifts were estimated using mean Hct and Hb measurements. Serum albumin was measured using an automated bromocresol green photometric method (BM-Hitachi 911). Data were analysed using a repeated measures ANOVA with Newman-Keuls post-hoc tests and are reported as Mean±SD. Six days of racing was associated with no change in body mass (D1=71.3±5.5, D6=71.3±5.6 kg, p>.05), a decrease in Hct (D1=47.7±1.7, D6=43.8±2.2%, p<.001) and Hb (D1=16.2±0.9, D6=14.8±0.8 g·dL−1, p<.001) and an increase in PV (D6=17.3±5.4%, p<.001). Although albumin did not significantly change from D1 (44.4±1.2 g·dL−1), there was a decrease from D3 to D6 (45.4±2.2 to 43.6±1.7 g·dL−1, p<.05). A 6-day stage race in these road cyclists caused Hct to be reduced by approximately 4% units primarily due to a 17% increase in PV. PV expansion over the last 3 days of racing is not linked to albumin enrichment. Data suggest that professional road cyclists with a naturally high Hct are more likely to exceed the UCI 50% Hct limit at the beginning, compared to the end of a stage race. Supported by an OAP grant and Roche Diagnostics Sponsorship

Comparison of biological activity and safety of recombinant canine erythropoietin with that of recombinant human erythropoietin in clinically normal dogs

Abstract Objective To determine whether recombinant canine erythropoietin (rcEPO) stimulates erythropoiesis in dogs without causing the immunogenicity problem (ie, erythroid hypoplasia) associated with recombinant human erythropoietin (rhEPO). Animals 13 clinically normal dogs. Procedure Dogs were randomly assigned to 2 groups; 1 group (n = 6) received rhEPO, whereas the other group (7) received rcEPO. Both groups received SC injections of diluent for 4 weeks before initiating treatment with erythropoietin (100 U/kg of body weight, SC, 3 times/wk). Hematocrit and absolute reticulocyte count were monitored weekly, CBC were done monthly, and bone marrow aspirates for cytologic evaluation were obtained before and at 4, 8, 16, and 24 weeks during treatment. Results Weekly mean Hct and absolute reticulocyte count increased in both groups of dogs during the first 2 weeks of treatment. For dogs receiving rhEPO, precipitous decreases in reticulocyte number and more gradual decreases in Hct were associated with development of erythroid hypoplasia. Dogs receiving rhEPO developed erythroid hypoplasia by week 4 (n = 4), 8 (1), or 16 (1). With cessation of rhEPO treatment after diagnosis of erythroid hypoplasia, RBC production recovered 5 to 11 weeks (median, 7 weeks) later. In contrast, rcEPO treatment caused sustained increases in Hct and reticulocytosis. None of the dogs receiving rcEPO developed erythroid hypoplasia. Conclusions rcEPO stimulated erythrocyte production in clinically normal dogs during a 24-week period without causing the erythroid hypoplasia encountered in rhEPO-treated dogs. Clinical Relevance Because rcEPO did not cause erythroid hypoplasia, rcEPO may represent an improved option, compared with rhEPO, for treatment of erythropoietin-dependent anemia in dogs. (Am J Vet Res 1999;60:636–642)

Intraoperative Autotransfusion in Small Children

Intraoperative Autotransfusion in Small Children

PREVALENCE AND RISK FACTORS FOR ANEMIA IN PEDIATRIC RENAL TRANSPLANT (RTx) RECIPIENTS

553 The importance of early recognition and treatment of anemia in patients with chronic renal insufficiency has received increasing attention with the publication of the NKF-DOQI anemia guidelines. In order to determine the prevalence of anemia in pediatric RTx recipients, all 86 patients at 3 pediatric transplant centers who were > 6 months post-transplant were evaluated. Anemia (HCT <33%) was present in 19.8%. More significant anemia(HCT <30%) was present in 14% of patients. Anemic patients had lower GFRs(Schwartz formula: ml/min/1.73m2) and were more likely to be receiving mycophenolate mofetil (MMF) and converting enzyme inhibitors (CEI).TableAnemia was more frequent in patients with GFR < 50 (58%), than in those with GFR >50 (9%), p<0.001. The frequency of anemia in RTx recipients with a GFR < 50 was comparable to that previously documented in children in the NAPRTCS registry with the same degree of renal insufficiency of their native kidneys (51.6%) (JASN 8:70, 1997). Patients with lower GFRs were more likely to be receiving MMF and CEI treatments (p <0.05). However, a linear regression model demonstrated a significant association between GFR and HCT, adjusting for therapy with MMF and/or CEI (p=0.005). The addition of an interaction term to this model suggested that MMF or CEI therapy is associated with a further decrease in HCT in patients with decreased GFRs. Iron studies were available in 9 patients with HCT <33%; only 1 had evidence of iron deficiency. There was no difference in the donor source between the two HCT groups. We conclude: 1) Anemia is present in 19.8% of RTx recipients > 6 mo post transplant; 2) The frequency of anemia in RTx recipients is comparable to the frequecy in children with insufficiency of their native kidneys; 3) Decreasing GFR is significantly associated with decreasing HCT after adjusting for MMF and CEI treatment.

Biological monitoring of workers exposed to low levels of 2-butoxyethanol.

(1) To assess the value of urinary butoxyacetic acid (BAA) measurement for the monitoring of workers exposed to low concentration of 2-butoxyethanol (BE); (2) to evaluate the in vivo effect of low occupational BE exposure on the erythrocyte lineage; and (3) to test the possible influence of genetic polymorphism for cytochrome P450 2E1 (CYP 2E1) on urinary BAA excretion rate. Thirty-one male workers exposed to BE in a beverage package production plant were examined according to their external (BE) and internal (BAA) solvent exposure. The effect of this exposure on erythrocyte lineage [red blood cell numeration (RBC), hemoglobin (Hb), hematocrit (Htc), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), haptoglobin (Hp), reticulocyte numeration (Ret) and osmotic resistance (OR)], hepatic [aspartate aminotransferase (GOT), alanine aminotransferase (GPT)] and renal [plasmatic creatinine, urinary retinol binding protein (RBP)] parameters was also investigated. DNA purified from whole blood was used for CYP 2E1 genotyping. Average airborne concentration of BE was 2.91 mg/m3 (0.59 ppm) with a standard deviation of 1.30 mg/m3 (0.27 ppm). There was a relatively good correlation between external and internal exposure estimated by measuring BAA in post-shift urine samples (average 10.4 mg/g creatinine; r = 0.55; P = 0.0012). Compared with a matched control group (n = 21) exposed workers had a statistically significant decrease (3.3%; P = 0.03) in Hct while MCHC was increased (2.1%; P = 0.02). No significant difference was observed either in other erythroid parameters or in hepatic and renal biomarkers. One exposed individual exhibited a mutant allele with increased cytochrome P450 oxidative activity which coincided with a very low urinary BAA excretion. Single determination of BAA in post-shift urine samples can be used to assess exposure to low levels of BE. A slight but significant effect on erythroid parameters suggesting membrane damage was observed in exposed workers. The influence of the genetic polymorphism for CYP 2E1 deserves further investigation for the interpretation of urinary BAA measurements.

Interference of angiotensin-converting enzyme inhibitors on erythropoiesis in kidney transplant recipients: role of growth factors and cytokines.

Recent data indicate that factors other than erythropoietin (EPO), such as insulin-like growth factor 1 (IGF-1), can promote erythropoiesis in vitro and correct the anemia of chronic renal failure in vivo. IGF-1 is produced by the liver under growth hormone control, as well as by other sources, including the kidney. The erythropoietic role of growth factors and cytokines and their possible modulation by angiotensin-converting enzyme inhibitors (ACEI) has never been explored. This study evaluated the serum levels of EPO, IGF-1, interleukin (IL)-2, IL-3, and granulocyte macrophage-colony-stimulating factor in 40 kidney transplanted patients with or without posttransplant erythrocytosis (PTE) and in 10 living kidney donors. Then, the effect of ACEI therapy on the above pattern was examined in patients with PTE. EPO and IGF-1 serum levels were significantly higher in patients with PTE than in patients without PTE and in living kidney donor subjects. ACEI therapy significantly reduced hematocrit (Hct) as well as circulating IGF-1 and EPO levels. Of note, the decrease in IGF-1 was prominent mainly in those patients whose EPO levels were not significantly modified by ACEI therapy. In all of the patients Hct levels displayed a direct relationship with circulating IGF-1 levels, but not with EPO concentration. Growth hormone did not significantly differ among the groups examined, whereas it steeply increased under ACEI. Finally, no significant difference in IL-2, IL-3, and granulocyte macrophage-colony-stimulating factor serum levels was detected. IGF-1 seems to play a role in the ACEI-related decrease of Hct in patients with PTE, chiefly in patients without any modification of EPO serum levels.

Effect of blood blow and haematocrit on the relationship between muscle venous PO2 and oxygen uptake in dog maximally contracting gastrocnemius in situ.

1. To clarify the limiting factors for peak VO2 (VO2,peak), we measured muscle venous PO2, (PVO2) and VO2,peak under various O2 delivery conditions (arterial O2 concentration x flow) via the alteration of blood flow and haematocrit (Hct) in anaesthetized dog gastrocnemius muscle (n = 11) stimulated by 1 Hz isometrically and tetanically. 2. Two levels of flow (high and moderate) were maintained by using a pump (150 and 100 mL/min per 100 g, respectively). Haematocrit was adjusted to 45 and 30% by isovolaemic haemodilution with dextran (MW 40,000). 3. The decrease in Hct induced a 31% decrease in O2 delivery (P < 0.05), a 9-12% decrease in PVO2, a 23% decrease in VO2,peak (P < 0.05) and a 12-14% increase in O2 extraction (VO2/O2 delivery) at both flow levels. The decrease in flow induced a 24-25% decrease in O2 delivery (P < 0.05), a 15-17% decrease in PVO2 (P < 0.05), a 9% decrease in VO2,peak (P < 0.05) and a 19-22% increase in O2 extraction (P < 0.05) at both Hct levels. 4. The results suggest that the limiting factor of VO/,peak, unrelated to O2 diffusion limitation (i.e. the change in the heterogeneity of VO2 to O2 delivery ratio among capillaries), due to lowering Hct may be different from that due to lowering blood flow in maximally contracting muscle.

Cerebral blood flow velocity after mannitol infusion in children.

There is conflicting evidence as to whether the effect of mannitol on brain bulk arises from haemodynamic, rheologic, or osmotic mechanisms. If mannitol alters cerebral haemodynamics by inducing vasoconstriction, this change should be reflected in cerebral blood flow velocity (CBFV) in the middle cerebral artery (MCA). The purpose of this study was to evaluate the effect of mannitol on CBFV in children. Children scheduled for intracranial surgery were enrolled. After a loading dose of 10 micrograms.kg-1 of fentanyl, general anaesthesia was maintained with fentanyl (3 micrograms.kg-1.hr-1), 66% nitrous oxide, and isoflurane (0.2-0.5% inspired). Mean and systolic CBFV (Vm and Vs) and pulsatility index (PI) were recorded with a transcranial Doppler (TCD) directed at the M1 segment of the MCA. Mannitol was administered, 1 gm.kg-1 iv over 15 min. The osmolality (Osm), haematocrit (Hct), mean arterial pressure (MAP), heart rate (HR), and TCD variables were recorded before and 15, 30, 45, and 60 min after the mannitol infusion. Mannitol infusion resulted in an increase in Osm and decrease in Hct (P < 0.05). Heart rate, MAP and arterial carbon dioxide tensions did not change (P > 0.05) during the measuring period. The Vm did not vary from baseline. The Vs and PI both increased briefly (P < 0.01 at 15 min and P < 0.05 at 30 min) after the mannitol, suggesting an increase in resistance distal to the MCA. The time course of CBFV changes produced by mannitol corresponds with previous animal data concerning cerebrovascular tone. Our results suggest that mannitol briefly increases cerebrovascular resistance and thereby diminishes cerebral blood volume.

Longitudinal study of the hematocrit of ad libitum fed and dietary restricted male F344 rats

A longitudinal study of age-change in the hematocrit (Hct) was conducted with ad libitum fed and dietary restricted male F344 rats. A progressive fall in Hct occurred over the age range of 3 to 20 months. The magnitude of this decrease in Hct was similar in ad libitum fed and dietary restricted rats. Whether this age-associated decline in Hct continues after 20 months of age cannot be answered with certainty because of the occurrence of diseases at advanced ages which can mask or exacerbate the effects of the aging processes on the Hct. Studies of similar design with males and females of other strains of rats are needed to establish that a decreasing Hct is characteristic of aging in this species.

Effects of changes in intravascular oncotic pressure on renal responses to volume loading in the saltwater-acclimated Pekin duck (Anas platyrhynchos)

The relative contributions of the intra-and extravascular compartments of the extracellular fluid (ECF) to the control of osmoregulatory renal functions were examined in saltwater-acclimated Pekin ducks. Having established steady-state diuresis and salt gland secretion by continuous infusion of 1 ml·min-1 isotonic Krebs-Ringer-Bicarbonate (KRB) solution, 5% dextran-70 was added to the infusate for 30 min thereby confining volume expansion to the intravascular compartment. General volume expansion by isotonic KRB caused a drop in plasma osmolality by 23 mOsm·kg-1, due to NaCl elimination by the salt glands, and decreases in hematocrit (het) and radioimmunologically measured plasma levels of Arg8-vasotocin (AVT) and Val5-angiotensin II (ANG II), whereas immunoreactivity associated with atrial natriuretic factor (ir-ANF) was increased. Adding 5% dextran-70 to the infusate left plasma osmolality and electrolytes unchanged but was followed by a further decrease in hct and a 36% increase in the plasma colloidosmotic pressure (COP) facilitating fluid shifts from the extra-to the intravascular compartment of the ECF. Plasma levels of AVT and ANG II remained unchanged, but ir-ANF rose three-fold, its increase being three times as great relative to the decrease in hct, as during general volume expansion by isotonic KRB solution. Arterial and central venous pressure measurements did not indicate changes in cardiovascular function. Hyperoncotic infusion initially induced marked antidiuresis with decreased osmolal excretion, despite a slightly elevated urine osmolality. This effects, however, was trasient and not proportional to the rise in COP, but rather seemed to be related to fluid shifts resulting from hyperoncotic loading. With tracer dilution techniques, reductions in both renal plasma flow and glomerular filtration rate were found to contribute to antidiuresis which was associated with reduced fractional water excretion. Salt gland secretion rate did not increase during hyperoncotic intravascular volume expansion but rather tended to decrease. The results of this study are in line with the idea that contributions of the interstitial fluid compartment (IFC) to volume-dependent control of osmoregulatory functions have to be considered. In the present study on saltwater-acclimated ducks, AVT, ANG II, and ir-ANF could be excluded as mediators of the adjustments in renal water and salt handling following fluid shifts due to hyperoncotic intravascular volume expansion.

Effects of Acute Normovolemic Hemodilution on Splanchnic Oxygenation and on Hepatic Histology and Metabolism in Anesthetized Pigs

Perioperative hemodilution (HD) has become an accepted means of reducing transfusion requirements. Therefore, the effects of limited (decrease in hematocrit [Hct] from 30 to 20%, "HD1") and severe (decrease in Hct from 20 to 14%, "HD2") acute normovolemic HD with 6% hydroxyethyl starch on splanchnic blood flows (electromagnetic flow probes), O2 uptakes and deliveries, surface O2 tensions (PO2) (Clark-type electrode), hepatic metabolism (organic acids), and hepatic histology (liver biopsies) were studied in nine pigs anesthetized and paralyzed with ketamine/flunitrazepam and pancuronium. HD1 caused significant (P less than 0.05) increases in cardiac output and all splanchnic flows. Only hepatic arterial blood flow increased twice as much as did cardiac output. Except for hepatic arterial O2 delivery, all splanchnic O2 deliveries decreased. Splanchnic O2 extractions increased, and O2 uptakes remained unchanged. There were no changes in mean surface PO2 values or in surface PO2 histograms of liver and small intestine; in portal or hepatic venous pH; and in hepatic uptake of pyruvate and lactate. In contrast, during HD2 (despite further increases in flows and O2 extractions) portal and hepatic venous pH decreased; mean surface PO2 of liver and small intestine decreased; and the liver surface PO2 histogram showed broadening and a shift to the left. However, hepatic uptake of lactate and pyruvate, and splanchnic O2 uptake remained unchanged, and histologic examination did not reveal significant cell injury. These data indicate that in this experimental model limited acute normovolemic HD was well tolerated by the splanchnic organs. After severe HD, gross liver function remained intact, but there was evidence that compensatory mechanisms (increases in flow and O2 extractions) were no longer fully able to counteract the decrease in splanchnic O2 delivery.

Hemolytic-Uremic Syndrome Following Bone Marrow Transplantation in Adults for Hematologic Malignancies

AbstractOne hundred and sixty eight adult patients with B-cell non-Hodgkin's lymphoma (NHL) and other hematologic malignancies who underwent autologous or allogeneic bone marrow transplantation (BMT) were investigated for the subsequent development of hemolytic-uremic syndrome (HUS). All patients were conditioned with cyclophosphamide and total body irradiation. When examined at 3-month intervals for the first year post-BMT, all patients had uniform measurements of hematocrit (Hct) and serum creatinine. Sixteen patients who initially exhibited Hct and creatinine values that were normal range for the BMT populations developed a sudden decrease in Hct and increase in creatinine between 3 and 11 months post-BMT and fulfilled the clinical and laboratory criteria for HUS. None of these patients had known active cytomegalovirus infection, graft-versus-host disease, or cyclosporine administration. The degree of decrease in Hct and creatinine elevation ranged from solely laboratory abnormalities to a clinically significant syndrome. Twelve of the 16 patients developed acute clinical complications of congestive heart failure, hypertension (HTN), or peripheral edema. Twelve patients required red blood cell support, whereas only four patients required platelet transfusions. Both hemolytic anemia and thrombocytopenia have resolved in virtually all cases. At a mean follow up of 18 months postdiagnosis, creatinine elevations have persisted along with HTN. All patients have survived without life-threatening long-term sequelae. With the increasing use of BMT as a curative modality for patients with hematologic malignancies, it becomes important to prospectively monitor patients for the development of HUS and its potential long-term impact on renal function.

Hemolytic-uremic syndrome following bone marrow transplantation in adults for hematologic malignancies

One hundred and sixty eight adult patients with B-cell non-Hodgkin's lymphoma (NHL) and other hematologic malignancies who underwent autologous or allogeneic bone marrow transplantation (BMT) were investigated for the subsequent development of hemolytic-uremic syndrome (HUS). All patients were conditioned with cyclophosphamide and total body irradiation. When examined at 3-month intervals for the first year post-BMT, all patients had uniform measurements of hematocrit (Hct) and serum creatinine. Sixteen patients who initially exhibited Hct and creatinine values that were normal range for the BMT populations developed a sudden decrease in Hct and increase in creatinine between 3 and 11 months post-BMT and fulfilled the clinical and laboratory criteria for HUS. None of these patients had known active cytomegalovirus infection, graft-versus-host disease, or cyclosporine administration. The degree of decrease in Hct and creatinine elevation ranged from solely laboratory abnormalities to a clinically significant syndrome. Twelve of the 16 patients developed acute clinical complications of congestive heart failure, hypertension (HTN), or peripheral edema. Twelve patients required red blood cell support, whereas only four patients required platelet transfusions. Both hemolytic anemia and thrombocytopenia have resolved in virtually all cases. At a mean follow up of 18 months postdiagnosis, creatinine elevations have persisted along with HTN. All patients have survived without life-threatening long-term sequelae. With the increasing use of BMT as a curative modality for patients with hematologic malignancies, it becomes important to prospectively monitor patients for the development of HUS and its potential long-term impact on renal function.

157 NEONATAL POLYCYTHEMIA: HEMODILUTION WITH SALINE VS SERUM. EFFECTS ON HEMATOCRIT, BLOOD- AND PLASMA VOLUME

We compared the effects of isovolumetric hemodilution (HD) with saline (n=8) and human serum (n=8) on venous hematocrit (Hct), plasma volume (PV, Evans Blue), blood volume (BV), and total plasma protein (TPP) in 16 term neonates with venous Hct>0.65. The exchange volume was 80 ml/kg × (Hct-55)/Hct, aiming at Hct 0.55. Results (±SD)Isovolumetric HD with saline resulted in a smaller (p<0.05) decrease in Hct than HD with serum and was not associated with an isovolemic substitution of withdrawn blood, out with a decrease of BV at the end and 4h after HD, because saline left the intravascular space already during HD.Conclusion: Rapid loss from the intravascular volume and the decrease of blood volume make saline less effective for HD in neonatal polycythemia and possibly for volume substitution in general.

Effect of Haematocrit on Wound Healing in Children

The effects of mild or moderate normovolaemic anaemia on wound healing (WH) continue to be debatable. The results of animal experiments and clinical experience are somewhat controversial. In this study, sixty-six boys, aged from 5 to 15, mean 10.1 years, were routinely operated on for a unilateral inguinal hernia, after which their WH was studied by the Cellstic device. Based on differential count of wound cells and their mutual transformed cell to cell ratios it was found that the optimum level of haematocrit (Hct) for WH was 37-39% with haemoglobin (Hb) values of 12.0-12.4 g/100 ml. Hct values under and over these limits began to retard WH significantly (p less than 0.02) without any visual signs of delay in WH. Both values are below the age adjusted means but just above the lower limits of normal. It is thus allowed, for the majority of healthy children with normal blood values, a mild decrease of Hct during the operation without any harmful effect on WH.

Hematocrit modulates response of ANP to volume expansion in immature rats

Compared with the adult, the immature kidney responds to acute volume expansion (VE) with reduced diuresis and natriuresis. The underlying mechanisms are poorly understood. Diuresis and natriuresis are blunted despite a lower hematocrit (Hct) in the immature rat, which should enhance the response to VE. The present study was designed to evaluate the role of atrial natriuretic peptide (ANP), its second messenger, guanosine 3',5'-cyclic monophosphate (cGMP), and Hct in the regulation of the renal response to acute saline VE (3% body wt) during postnatal development in rats. Anesthetized Sprague-Dawley rats were studied in the preweaning (group P) or postweaning period (group W). In additional groups, Hct was increased in preweaned rats (group PI) and decreased in postweaned rats (group WD) by isovolemic exchange transfusion before VE. Although control plasma ANP concentration [( ANP]) was not different among the four groups, the increased diuretic and natriuretic response to VE in group W was associated with a greater increase in [ANP] and urinary cGMP excretion (UcGMPV) than in group P (P less than 0.05). Experimental increases in Hct in group PI resulted in greater [ANP] after VE but a reduction in UcGMPV and diuresis (P less than 0.05), whereas decrease in Hct in group WD increased UcGMPV without a significant effect on [ANP], diuresis, or natriuresis. We conclude that ANP may contribute to the increasing renal response to VE with maturation and that Hct modulates ANP release, UcGMPV, and the renal response to VE in postnatal maturation.

V. Aerobic Performance at Altitude: Effects of Acclimatization and Hematocrit with Reference to Training

The aim of the present investigation carried out on six members of the Swiss 1981 Mt. Lhotse Shar (8398 m) expedition was to assess the quantitative role of some of the determinants of VO2max at altitude. The loss of VO2max expected for the investigated altitude range was partially counterbalanced by the training undergone by the subjects during the approach to the base camp. delta VO2max was -18% instead of the expected 30%-35%. The VO2max value attained shortly after arrival at 5200 m was not significantly increased (38.4 +/- 4.4 SD vs 36.9 +/- 3.3 ml O2.kg-1.min-1) with a progressive rise of Hb from 16.4 +/- 0.8 to 18.2 +/- 1 g/100 ml of blood. Hemodilution, by oral administration of 2 liters of the isosmolar solution ISOSTAR, at 5200 m led to a 2.3% decrease of Hct and a 7.3% reduction of VO2max per kg of body weight. The product of heart rate times systolic arterial pressure ("double product") was somewhat (but not significantly) greater in hypoxia than in normoxia at all work loads. The maximum value for this product, however, was 10%-15% lower at 5200 than at 400 m. The increase of Hb from 15.1 +/- 0.7 to 17.1 +/- 1.6 g/100 ml of blood pre- to post-expedition was not accompanied by a significant increase of VO2max determined at 400 m either absolute or per kg of body weight.