Changes In Plasma Volume Research Articles

Nightly Sustained Lower Body Negative Pressure Attenuates Reductions in Cerebral Blood Flow Associated with Simulated Microgravity

Background Cognitive impairment is a common maladaptation to space flight and may be related to microgravity-induced reductions in cerebral blood flow (CBF). One of the most prominent hemodynamic adjustments to microgravity that may contribute to cardiovascular impairment is a loss of plasma and blood volume that occurs to partially offset a cephalad fluid shift due to the loss of normal hydrostatic gradients. Lower body negative pressure (LBNP) may be an effective countermeasure to shift blood caudally, reduce central venous pressure, unload baroreceptors and partially restore diurnal hydrostatic gradients to preserve plasma volume and CBF. Hypothesis Sustained (8 hours) nightly LBNP will restore diurnal hemodynamic shifts, preserve plasma volume, and improve CBF during three days of simulated microgravity using a supine zero-degree bed rest model. Methods Nine healthy subjects (4 female; 30±9 years) completed three days of supine (0°) bed rest with and without eight hours of sustained nightly LBNP (-20 mmHg) in a randomized, crossover design. Total blood and plasma volume (carbon monoxide-rebreathing), and total CBF (combined ultrasound of vertebral and internal carotid arteries) were measured on the first and last morning of bed rest with LBNP off. Central venous pressure (CVP) was measured during spontaneous breathing with a peripherally inserted central catheter and end tidal CO2 (ETCO2) was monitored by nasal cannula. Values are presented as mean ± SD or mean and 95% CI where appropriate. Results CVP increased significantly from the seated to supine position (+9.1 ± 2.4mmHg, P < 0.001), and nightly LBNP caused a sustained reduction in supine CVP (5.7 ± 2.2mmHg to 1.2 ± 1.4mmHg, P < 0.001), indicating effective redistribution of blood volume. Plasma volume decreased similarly in the control and in the LBNP condition (Δ plasma volume: control: -394 ml [CI:-684 to -184], LBNP: -429 ml [CI -719 to -39; p=0.95). ETCO2 decreased similarly in both conditions (ΔETCO2: Control: -1.4 mmHg [CI: -3.2 to 0.32], LBNP: -0.4 mmHg [CI:-1.8 to 0.89]; P=0.27). However, LBNP attenuated the fall in total CBF by ~41% (Δ tCBF: control: -174 ml/min [CI: -107 to-241], LBNP: -102 ml/min [CI: -35 to -170]; P=0.04). Changes in plasma volume were directly correlated to changes in total CBF (Pearson r2=0.49; P=0.009). Conclusions Low level LBNP may be an effective countermeasure against microgravity-induced reduction in total CBF. While LBNP was not effective at preserving plasma volume, changes in total CBF were directly associated with changes in plasma volume. LBNP during sleep may be an effective counter measure against some but not all cardiovascular consequences of long-duration space flight.

Plasma volume expansion is impaired in pregnancy after recovery from renal ischemia reperfusion injury

Healthy pregnancy is characterized by plasma volume expansion resulting in a significant increase in renal demands. Low plasma volume expansion during pregnancy is associated with poor fetal outcomes, including intrauterine growth restriction, and is also associated with decreased maternal renal function. Previous studies in our laboratory report that after recovery from renal ischemia reperfusion (IR) injury, female Sprague Dawley rats fail to increase renal function during pregnancy with poor maternal and fetal outcomes. The goal of the current study was to assess plasma volume and renal changes during pregnancy in our model of pregnancy after IR. We hypothesized that plasma volume expansion is impaired in pregnancy in dams after recovery from IR injury. Female Sprague Dawley rats (12 weeks of age, n=4-6) were randomized to receive either 45 minutes of warm, bilateral renal ischemia or sham surgery. IR injury was confirmed by a significant increase in plasma creatinine 24 hours after surgery (compared to sham controls). Rats were then given one month to recover. Full recovery from IR was confirmed by return of plasma creatinine and urinary protein excretion to baseline levels. Control and IR rats were randomized to either be mated with age-matched males with pregnancy confirmed by vaginal cytology or serve as virgin controls. Plasma volume was measured during late pregnancy on gestational day 20 by the Evans blue method in the pregnant rats and in age-matched virgin controls. Kidneys were collected for histological analysis by H&E staining, and glomerular area was measured in 20 glomeruli/kidney. Plasma volume increased during pregnancy in both control and IR dams compared to virgin controls, but the increase was greater in control dams than IR dams (Table, 2-Way ANOVA, Ppregnancy <0.01, PIR <0.01, PInteraction <0.01). Pregnancy also resulted in an increase in glomerular size in both control and IR dams compared to virgin controls, but this increase was also greater in the controls dams (Table, 2-Way ANOVA, Ppregnancy <0.01, PIR =0.01, PInteraction =0.02). These data suggest that despite recovery from IR injury, female rats fail to increase plasma volume in pregnancy along with failure to increase glomerular size. We propose that this failure to increase plasma volume in pregnancy is responsible for the poor fetal outcomes observed in this model. Further studies will examine the mechanisms responsible for plasma volume expansion in pregnancy, and why plasma volume fails to expand after recovery from IR injury.

Fluid Shifts with Acute Exposure to Normobaric and Hypobaric Hypoxia

Purpose To determine the body fluid shifts that occur with exposure to normobaric hypoxia (NH) and hypobaric hypoxia (HH) compared to normobaric normoxia (NN). Methods Eighteen males and females (male=10, female=8, age 35±7 yrs) completed three trials on back to back days in a randomized order. NN was conducted at sea level, NH was conducted at sea level but breathing a gas mixture to simulate 4,617 m of elevation, and HH was conducted at 4,617 m of terrestrial elevation. The time and rate of hypoxia exposure was consistent between NN and HH (0 m to 4,617 m in 90 minutes). Finger-stick blood samples were taken after the 90 minute intervention and analyzed for hemoglobin and hematocrit to calculate plasma volume shifts and urine was collected to measure urine specific gravity. After 10 minutes of supine rest, body water was analyzed via BIA. Results Plasma volume change was not altered by NH relative to NN (-3.77±8.36%, p = 0.073), but lower in HH relative to NN (-16.610±7.84%, p<0.001). Urine specific gravity was similar between all trials (p=0.120, main effect). Total body water was not different between NN (43.8±7.6 L) and NH (43.7±7.7 L, p=0.492), but was lower in HH (43.0±7.6 L) than NN (p<0.001) and NH (p<0.001). Extracellular fluid was not different between NN (16.35±2.85 L) and NH (16.32±2.84 L, p=0.696), but was lower in HH (16.08±2.78 L) than NN (p<0.001) and NH (p=0.006). Intracellular Fluid was not different between NN (27.41±4.81 L) and NH (27.33±4.89 L, p=0.420) but was lower in HH (26.97±4.80 L) than NN (p<0.001) and NH (p=0.016). Conclusion Body fluid shifts are stimulated by an alteration of barometric pressure and not by hypoxia. Caution should be made when applying data from studies conducted in NH to HH.

Direct evaluation of the phase diagrams of dense multicomponent plasmas by integration of the Clapeyron equations.

Accurate phase diagrams of multicomponent plasmas are required for the modeling of dense stellar plasmas, such as those found in the cores of white dwarf stars and the crusts of neutron stars. Those phase diagrams have been computed using a variety of standard techniques, which suffer from physical and computational limitations. Here we present an efficient and accurate method that overcomes the drawbacks of previously used approaches. In particular, finite-size effects are avoided as each phase is calculated separately; the plasma electrons and volume changes are explicitly taken into account; and arbitrary analytic fits to simulation data as well as particle insertions are avoided. Furthermore, no simulations at "uninteresting" state conditions, i.e., away from the phase coexistence curves, are required, which improves the efficiency of the technique. The method consists of an adaptation of the so-called Gibbs-Duhem integration approach to electron-ion plasmas, where the coexistence curve is determined by direct numerical integration of its underlying Clapeyron equation. The thermodynamics properties of the coexisting phases are evaluated separately using Monte Carlo simulations in the isobaric semigrand canonical ensemble (NPTΔμ). We describe this Monte Carlo-based Clapeyron integration method, including its basic physical and numerical principles, our extension to electron-ion plasmas, and our numerical implementation. We illustrate its applicability and benefits with the calculation of the melting curve of dense carbon-oxygen plasmas under conditions relevant for the cores of white dwarf stars and provide analytic fits to implement this new melting curve in white dwarf models. While this work focuses on the liquid-solid phase boundary of dense two-component plasmas, a wider range of physical systems and phase boundaries are within the scope of the Clapeyron integration method, which had until now only been applied to simple model systems of neutral particles.

Interval-induced metabolic perturbation determines tissue fluid shifts into skeletal muscle.

Intense interval exercise has proven to be as effective as traditional endurance exercise in improving maximal oxygen uptake. Shared by these two exercise regimes is an acute reduction in plasma volume, which is a suggested stimulus behind exercise‐induced increases in blood volume and maximal oxygen uptake. This study aimed to link exercise‐induced metabolic perturbation with volume shifts into skeletal muscle tissue. Ten healthy subjects (mean age 33 ± 8 years, 5 males and 5 females) performed three 30 s all‐out sprints on a cycle ergometer. Upon cessation of exercise magnetic resonance imaging, 31Phosphorus magnetic resonance spectroscopy and blood samples were used to measure changes in muscle volume, intramuscular energy metabolites and plasma volume. Compared to pre‐exercise, muscle volume increased from 1147.1 ± 35.6 ml to 1283.3 ± 11.0 ml 8 min post‐exercise. At 30 min post‐exercise, muscle volume was still higher than pre‐exercise (1147.1 ± 35.6 vs. 1222.2 ± 6.8 ml). Plasma volume decreased by 16 ± 3% immediately post‐exercise and recovered back to – 5 ± 6% after 30 min. Principal component analysis of exercise performance, muscle and plasma volume changes as well as changes in intramuscular energy metabolites showed generally strong correlations between metabolic and physiological variables. The strongest predictor for the volume shifts of muscle and plasma was the magnitude of glucose‐6‐phosphate accumulation post‐exercise. Interval training leads to large metabolic and hemodynamic perturbations with accumulation of glucose‐6‐phosphate as a possible key event in the fluid flux between the vascular compartment and muscle tissue.

Effect of Single Session of High Intensity Interval Exercise on Some Immune and Inflammatory Factors in Male Athletes and the Risk of Infection to Coronavirus

Introduction: High Intensity exercise is one of the effective factors on immune and inflammatory factors. The purpose of this study was to determine the single session of high intensity interval exercise (CrossFit) on levels of leukocytes, neutrophils, lymphocytes, monocytes, lactic acid and C- reactive protein (CRP) of male athletes to make decision for doing this exercise in coronavirus prevalence period. Methods: In this Causal-comparative study, 32 male athletes were selected as participants (with mean of age 26.9±4.7 year, height 177 ± 5 cm, weight 80.7±6.4 kg). Exercise session included a 400-meter running on treadmill, triple dead lift movement, pull-up (30 repetition), swing of kettlebell (30 kg) and throwing of 20 sand balls. Blood sampling, CBC and biochemistry auto analyzer tests were used for measuring leukocytes, lactic acid and CRP. In addition, ANOVA with repeated measure, Friedman, Wil-kaksun and Bonferroni post hoc tests were used to examine the differences between variables in resting position, post-exercise, and after modify the results by consideration of plasma volume changes using SPSS version 16 software. Results: The results showed significant increase in lactic acid (P&lt;0.001), CRP (P=0.006), leukocytes (P&lt;0.001) and lymphocytes (P=0.001), but the increase of monocytes was no significant (P=0.705). In addition, the results of study showed significant decrease in neutrophils (P=0.005) and plasma volume (P&lt;0.001). Furthermore, the significant results of some indices were removed by consideration of plasma volume change (P&gt;0.05). Conclusion: The single session of high intensity interval exercise makes disorder in immune and inflammation responses in athletes. Therefore, it has been suggested not to do intensive exercise at coronavirus prevalence period and consider enough time for recovery after high intensity exercise.

Effect of Empagliflozin as an Add-On Therapy on Decongestion and Renal Function in Patients With Diabetes Hospitalized for Acute Decompensated Heart Failure: A Prospective Randomized Controlled Study.

Empagliflozin reduces the risk of hospitalization for heart failure in patients with type 2 diabetes and cardiovascular disease. We sought to elucidate the effect of empagliflozin as an add-on therapy on decongestion and renal function in patients with type 2 diabetes admitted for acute decompensated heart failure. The study was terminated early due to COVID-19 pandemic. We enrolled 59 consecutive patients with type 2 diabetes admitted for acute decompensated heart failure. Patients were randomly assigned to receive either empagliflozin add-on (n=30) or conventional glucose-lowering therapy (n=29). We performed laboratory tests at baseline and 1, 2, 3, and 7 days after randomization. Percent change in plasma volume between admission and subsequent time points was calculated using the Strauss formula. There were no significant baseline differences in left ventricular ejection fraction and serum NT-proBNP (N-terminal pro-B-type natriuretic peptide), hematocrit, or serum creatinine levels between the 2 groups. Seven days after randomization, NT-proBNP level was significantly lower in the empagliflozin group than in the conventional group (P=0.040), and hemoconcentration (≥3% absolute increase in hematocrit) was more frequently observed in the empagliflozin group than in the conventional group (P=0.020). The decrease in percent change in plasma volume between baseline and subsequent time points was significantly larger in the empagliflozin group than in the conventional group 7 days after randomization (P=0.017). The incidence of worsening renal function (an increase in serum creatinine ≥0.3 mg/dL) did not significantly differ between the 2 groups. In this exploratory analysis, empagliflozin achieved effective decongestion without an increased risk of worsening renal function as an add-on therapy in patients with type 2 diabetes with acute decompensated heart failure. Registration: URL: https://www.umin.ac.jp/ctr/index.htm; Unique identifier: UMIN000026315.

Effects of 150- and 450-mL Acute Blood Losses on Maximal Oxygen Uptake and Exercise Capacity.

This study investigated whether maximal oxygen uptake (V˙O2max) and exercise capacity are affected by small acute blood loss (150 mL) and elucidated compensatory mechanisms. Thirteen male subjects (V˙O2max, 63 ± 9 mL·kg-1·min-1; mean ± SD) performed incremental exercise to exhaustion on a cycle ergometer in three experimental conditions: in euvolemia (control; blood volume [BV], 6.0 ± 0.7 L) and immediately after acute BV reductions of 150 mL (BVR150mL) and 450 mL (BVR450mL). Changes in plasma volume (PV) and BV during exercise were calculated from hematocrit, hemoglobin concentration, and hemoglobin mass (carbon monoxide rebreathing). The reduction in V˙O2max per milliliter of BVR was 2.5-fold larger after BVR450mL compared with BVR150mL (-0.7 ± 0.3 vs -0.3 ± 0.6 mL·min-1·mL-1, P = 0.029). V˙O2max was not significantly changed after BVR150mL (-1% ± 2%, P = 0.124) but reduced by 7% ± 3% after BVR450mL (P < 0.001) compared with control. Peak power output only decreased after BVR450mL (P < 0.001). At maximal exercise, BV was restored after BVR150mL compared with control (-50 ± 185 mL, P = 0.375) attributed to PV restoration, which was, however, insufficient in restoring BV after BVR450mL (-281 ± 184 mL, P < 0.001). The peak heart rate tended to increase (3 ± 5 bpm, P = 0.062), whereas the O2 pulse (-2 ± 1 mL per beat, P < 0.001) and vastus lateralis tissue oxygenation index (-4% ± 8% points, P = 0.080) were reduced after BVR450mL, suggesting decreased stroke volume and increased leg O2 extraction. The deteriorations of V˙O2max and of maximal exercise capacity accelerate with the magnitude of acute blood loss, likely because of a rapid PV restoration sufficient to establish euvolemia after a small but not after a moderate blood loss.

Plasma volume contraction reduces atrial natriuretic peptide after four days of hypobaric hypoxia exposure.

We investigated whether low arterial oxygen tension ([Formula: see text]) or hypoxia-induced plasma volume (PV) contraction, which reduces central blood volume (BV) and atrial distension, explain reduction in circulating atrial natriuretic peptide (ANP) after prolonged hypoxic exposure. Ten healthy males were exposed for 4 days to hypobaric hypoxia corresponding to an altitude of 3,500 m. PV changes were determined by carbon monoxide rebreathing. Venous plasma concentrations of midregional proANP (MR-proANP) were measured before and at the end of the exposure. At the latter time point, the measurement was repeated after 1) restoration of [Formula: see text] by breathing a hyperoxic gas mixture for 30 min and 2) restoration of BV by fluid infusion. Correspondingly, left ventricular end-diastolic volume (LVEDV), left atrial area (LAA), and right atrial area (RAA) were determined by ultrasound before exposure and both before and after fluid infusion at the end of the exposure. Hypoxic exposure reduced MR-proANP from 37.9 ± 18.5 to 24.5 ± 10.3 pmol/L (P = 0.034), LVEDV from 107.4 ± 33.5 to 91.6 ± 26.3 mL (P = 0.005), LAA from 15.8 ± 4.9 to 13.3 ± 4.2 cm2 (P = 0.007), and RAA from 16.2 ± 3.1 to 14.3 ± 3.5 cm2 (P = 0.001). Hyperoxic breathing did not affect MR-proANP (24.8 ± 12.3 pmol/L, P = 0.890). Conversely, fluid infusion restored LVEDV, LAA, and RAA to near-baseline values (108.0 ± 29.3 mL, 17.2 ± 5.7 cm2, and 17.2 ± 3.1 cm2, respectively, P > 0.05 vs. baseline) and increased MR-proANP to 29.5 ± 13.3 pmol/L (P = 0.010 vs. preinfusion and P = 0.182 vs. baseline). These findings support that ANP reduction in hypoxia is at least partially attributed to plasma volume contraction, whereas reduced [Formula: see text] does not seem to contribute.

＜Editors' Choice＞ Prognostic utility of multipoint nutritional screening for hospitalized patients with acute decompensated heart failure.

ABSTRACTThis study aimed to evaluate the impact of serial changes in nutritional status on 1-year events including all-cause mortality or rehospitalization owing to heart failure (HF) among hospitalized patients with acute decompensated HF (ADHF). The study subjects comprised 253 hospitalized patients with ADHF. The controlling nutritional status (CONUT) score was assessed both at hospital admission and discharge. The subjects were divided into three groups according to nutritional status using CONUT score: normal (0 and 1), mild risk (2–4), and moderate to severe risk defined as malnutrition (5–12). We observed nutritional status was improved or not. The incidence of malnutrition was 30.4% at hospital admission and 23.7% at discharge, respectively. Malnutrition was independently associated with 1-year events among hospitalized patients with ADHF. Presence or absence of improvement in nutritional status was significantly associated with 1-year events (P < 0.05), that was independent of percentage change in plasma volume in multivariate Cox regression analyses. We determined a reference model, including gender and estimated glomerular filtration rate, using multivariate logistic regression analysis (P < 0.05). Adding the absence of improvement in nutritional status during hospitalization to the reference model significantly improved both NRI and IDI (0.563, P < 0.001 and 0.039, P = 0.001). Furthermore, malnutrition at hospital discharge significantly improved NRI (0.256, P = 0.036) In conclusion, serial changes in the nutritional status evaluated on the basis of multiple measurements may provide more useful information to predict 1-year events than single measurement at hospital admission or discharge in hospitalized patients with ADHF.

Cardiovascular responses to heat acclimatisation in athletes with spinal cord injury

ObjectivesTo determine the effect of heat acclimatisation (HA) training on blood profile and resting cardiac function in elite athletes with spinal cord injury (SCI). DesignQuasi-experimental. MethodsEleven athletes (10m, 1f) with SCI (C5-T3) completed a five-day isothermic HA protocol whereby gastrointestinal temperature (Tc) was elevated to and maintained at ∼38.5 degrees Celsius (°C) via intermittent exercise for sixty minutes each day. Blood samples were collected pre- and post-HA to determine changes in plasma volume (PV). Doppler ultrasound of the left-ventricular outflow tract and 2-d speckle tracking echocardiography were performed in a subset of athletes (n=5) to determine changes in indices of resting left-ventricular function and mechanics, respectively. ResultsTen athletes were successfully able to raise and maintain Tc to 38.5°C. There was a non-significant increase in PV with HA training (ΔPV%: 3.0±5.4%, p=0.086). Following HA, resting HR decreased (63±4 pre-HA vs. 58±5 bpm post-HA, p=0.020), velocity time integral (21.4±2.7 vs. 23.7±3.0cm, p=0.045) and stroke volume increased (64.8±7.6 vs. 70.2±10.5mL, p=0.055). ConclusionsOur findings suggest a short-term HA protocol in athletes with SCI is safe and may induce beneficial changes in indices of resting left-ventricular function — however results are highly individualized. Future studies on HA in athletes with SCI should focus on determining mechanisms of adaptation and performance outcomes.

Diuresis-Related Weight Loss Reflects Interstitial Compartment Decongestion with Minimal Impact on Intravascular Volume Expansion or Outcomes in Post-Acute Heart Failure: Metrics of Decongestion and Volume Status

BackgroundFindings from heart failure (HF) studies linking diuresis-related weight loss to clinical decongestion and outcomes are mixed. Differential responses of interstitial and intravascular volume compartments to diuretic therapy and heterogeneity in volume profiles may confound the clinical interpretation of weight loss in patients with HF. Methods and ResultsData were prospectively collected in hospitalized patients requiring diuresis. Plasma volume (PV) was measured using I-131-labelled albumin indicator-dilution methodology. The cohort was stratified by tertiles of weight loss and analyzed for interstitial fluid loss relative to changes in PV and HF-related morality or first rehospitalization. Among 92 patients, the admission PV was expanded +42% (4.7 ± 1.2 L) above normal with significant variability (14% normal PV, 18% mild-moderate expansion, and 68% with large PV expansion [>+25% above normal]). With diuresis there were proportional decreases in interstitial volume (–6.5 ± 4.4%) and PV (–7.5 ± 11%); however, absolute decreases in the PV (–254 mL, interquartile range –11 to –583 mL) were less than 10% of interstitial volume loss (–5040 mL, interquartile range –2800 to –7989 mL); greater interstitial fluid loss did not translate into better outcomes (log-rank P = .430). ConclusionsDiuresis-related decreases in weight reflect fluid loss from the interstitial compartment with only minor changes in the PV and without an impact on outcomes. Further, the degree of PV expansion at hospital admission does not drive the magnitude of the diuresis response, even with a wide spectrum of body weights; interstitial fluid overload is preferentially targeted and PV relatively preserved. Therefore, greater interstitial fluid loss reflects clinical decongestion, but not better outcomes, and a limited association with intravascular volume profiles potentially confounding weight loss as a prognostic metric in HF.

Effects of physical therapy on hyaluronan clearance and volume regulating hormones in lower limb lymphedema patients: A pilot study.

Lymphedema is manifested as a chronic swelling arising due to stasis in the lymphatic flow. No cure is currently available. A non-invasive treatment is a 3 week complete decongestive therapy (CDT), including manual lymphatic drainage and compression bandaging to control swelling. As CDT leads to mobilization of several liters of fluid, effects of CDT on hyaluronan clearance (maker for lymphatic outflow), volume regulating hormones, total plasma protein as well as plasma density, osmolality and selected electrolytes were investigated. In this pilot study, we assessed hyaluronan and volume regulating hormone responses from plasma samples of nine patients (three males, six females, aged 55 ± 13 years) with lower limb lymphedema stage II-III, before - and after - CDT. A paired non-parametric test (Wilcoxon) was used to assess hormonal and plasma volume changes. Correlation was tested using Spearman's correlation. The main findings of this novel study are that lymphedema patients lost volume and weight after therapy. Hyaluronic acid did not significantly change pre- compared to post-CDT. Aldosterone increased significantly after therapy, while plasma renin activity increased, but not significantly. Plasma total protein, density, osmolality and sodium and chloride did not show differences after CDT. To our knowledge, no study has previously investigated the effects of CDT on volume regulating hormones or electrolytes. To identify the time-course of volume regulating hormones and lymphatic flow changes induced by CDT, future studies should assess these parameters serially over 3 weeks of therapy.

Rapid Weight Loss in Congolese Judo: Energy Profile, Performance and Haematological Effects

While the deleterious effects of rapid weight loss (RWL) on the health in combat sports athletes are well known, the issue of exertion energy expenditure and motor performance remains controversial. The aim of this study was to investigate the impact of RWL on energy cost and judo performance, and associated haematological characteristics. Among 21 top Congolese judoists who took part in an intensive judo program lasting 5 1/2 days (or 11 sessions), 16 of them rapidly lost 4% to 5.5% of body mass; corollarly with a reclassification in one of the 3 weight categories: -60 kg (n = 7), -80 kg (n = 5) and -100 kg (n = 4). During sessions 1 and 11, the energy cost during the different training sequences was evaluated from the heart rate (HR). During the program, a judo performance test evaluated 2 performance indicators: the number of uchi-komi achieved and the height of uke’s center of gravity during a throw. Basal blood parameters were determined before RWL and at S1, S11 (after the judo combat series). The results show a significant increase in heart rate from session S1 to session S11, in the different training sequences. HR after fights was around 98% of HRmax. In addition, a significant decrease in number of uchi-komi was observed on each of the bearings 4 to 6 and throughout the performance test, and in height of uke’s center of gravity during fall movements. While most of the basal blood parameters remained unaltered during the program, red blood cell was reduced significantly and a significant plasma volume changes increase was found. The modification of each of the variables measured thus reflects the negative effect of the rapid weight loss associated to the increase in energy cost in judo.

Effects of short duration high intensity competition on cardiac and cell damage biomarkers

The purpose of this study was to investigate the cardiac biomarkers like cardiac troponin T (cTnT), cardiac troponin I, and creatine kinase-MB (CK-MB) and the cell damage biomarkers including creatine phosphokinase (CPK), C-reactive protein (CRP), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in response to a short-duration high-intensity competition with correction of the post-exercise raw data with the plasma volume loss in trained athletes. Thirty-two male athletes (age, 26.9±4.7 years) competed in 8 min high-intensity competition. The competition items included: running for 400 meters; three-stage deadlifting; bar pulling up; and 30 kg kettlebell swinging. Venous blood samples were obtained before and immediately after the competition and biomarkers analysed. Plasma volume changes were estimated from haemoglobin and haematocrit readings before and after the competition. A significant increase was shown immediately after the competition compared to resting in cTnT, AST, ALT, CPK, and CRP (P&lt;0/001). CK-MB showed no significant difference. When raw data were corrected for plasma volume loss, CPK showed a significant increase (P&lt;0.001), and LDH and CK-MB a significant decrease (P&lt;0.001), however cTnT, AST, ALT and CRP showed no significant difference. The plasma volume loss can affect the response of cardiac and cellular damage biomarkers to exercise. High-intensity competition for 8 min did not elevate the cardiac biomarkers, but elevated the muscle biomarkers.

Mountain Bike Racing Stimulates Osteogenic Bone Signaling and Ingesting Carbohydrate-Protein Compared With Carbohydrate-Only Prevents Acute Recovery Bone Resorption Dominance.

Oosthuyse, T, Bosch, AN, Kariem, N, and Millen, AME. Mountain bike racing stimulates osteogenic bone signaling and ingesting carbohydrate-protein compared with carbohydrate-only prevents acute recovery bone resorption dominance. J Strength Cond Res 35(2): 292-299, 2021-Mountain biking, unlike road cycling, includes vibrational accelerations but whether it stimulates osteogenic signaling remains unknown. Furthermore, exercise nutrition influences bone turnover, and the effect of ingesting protein during multiday racing was investigated. We measured plasma bone turnover markers, C-terminal telopeptide of type1-collagen (β-CTX) and N-terminal propeptides of type1-procollagen (P1NP), and osteocyte mechanosensory signaling factor, sclerostin (SOST), corrected for plasma volume change, before (pre-day 1) and 20-60 minutes after (post-day 3) a multiday mountain bike race in 18 male cyclists randomly assigned to ingest carbohydrate-only (CHO-only) or carbohydrate-with-casein protein hydrolysate (CHO-PRO) during racing. Fourteen cyclists (n = 7 per group) completed the race, and data were analyzed with p < 0.05 accepted as significant. Plasma SOST decreased similarly in both groups (mean ± SD, CHO-only: 877 ± 451 to 628 ± 473 pg·ml-1, p = 0.004; CHO-PRO: 888 ± 411 to 650 ± 443 pg·ml-1, p = 0.003), suggesting that osteocytes sense mountain biking as mechanical loading. However, the bone formation marker, P1NP, remained unchanged in both groups, whereas the bone resorption marker, β-CTX, increased in CHO-only (0.19 ± 0.034 to 0.31 ± 0.074 ng·ml-1, p = 0.0036) but remained unchanged in CHO-PRO (0.25 ± 0.079 to 0.26 ± 0.074 ng·ml-1, p = 0.95). Mountain bike racing does stimulate osteogenic bone signaling but bone formation is not increased acutely after multiday mountain biking; investigation for a delayed effect is warranted. The acute recovery increase in bone resorption with CHO-only is prevented by ingesting CHO-PRO during racing.

Effects of different mean arterial pressure targets on plasma volume, ANP and glycocalyx-A randomized trial.

BackgroundArterial haematocrit (Hct) has been shown to decrease after anaesthesia induction, most probably because of an increased plasma volume (PV). The primary objective was to quantify change in PV if mean arterial pressure (MAP) was kept at baseline level or allowed to decrease to 60 mm Hg. Our secondary objective was to evaluate underlying mechanisms of this response.MethodsTwenty‐four coronary artery bypass patients were randomized to a higher (90 mm Hg, intervention group) or lower (60 mm Hg, control group) MAP by titration of norepinephrine. During the experimental procedure, no fluids were administered. Baseline PV was measured by 125I‐albumin and the change in PV was calculated from the change in Hct. Changes in MAP, plasma 125I‐albumin, colloid osmotic pressure, albumin, Mid Regional‐pro Atrial Natriuretic Peptide (MR‐proANP) and endothelial glycocalyx components were measured from baseline to 50 minutes after anaesthesia induction.ResultsThe MAP during the trial was 93 ± 9 mm Hg in the intervention group and 62 ± 5 mm Hg in the control group. PV increased with up to 420 ± 180 mL in the control group and 45 ± 130 mL in the intervention group (P < .001). Albumin and colloid osmotic pressure decreased significantly more in the control group. MR‐proANP increased in the control group but no shedding of the glycocalyx layer was detected in either of the groups.ConclusionAllowing mean arterial pressure to fall to 60 mm Hg during anaesthesia induction, increases the plasma volume due to reabsorption of interstitial water, with no ANP‐induced degradation of the endothelial glycocalyx.

Why is Diuresis-related Weight Loss Not a Consistent Predictor of Clinical Outcomes in Heart Failure? -need to Account For Variability in Volume Status

Introduction Change in body weight is a common metric used to assess adequacy of decongestive therapy in patients hospitalized for heart failure (HF). However, the findings of clinical studies linking this metric to clinical decongestion and outcomes are mixed. We propose this reflects the failure to take into account biologic variability in intravascular volume status which would impact response to therapy. Methods Data were prospectively collected in hospitalized patients requiring diuresis. Plasma volume (PV) was measured using I-131-labelled albumin indicator-dilution methodology. The cohort was stratified by median diuresis-related weight loss and analyzed for 1-year outcome of HF-related mortality or 1st re-hospitalization, and the relation of change in weight to change in PV admission to discharge. Results The cohort was composed of 138 patients with median weight loss of 6 (IQR -3.2, -8.1) kg during hospitalization (5 IQR 4, 6 days). Greater than median weight loss (Figure 1) did not result in better outcomes. At the time of hospital discharge the subgroup with greater weight loss (N=61) paradoxically demonstrated greater absolute (4.8±1.0 vs. 4.2±1.0 liters, p<0.001) and relative PV expansion(+44±29% vs. +33±23% above normal, p=0.023). Also demonstrated was marked heterogeneity in PV status in both subgroups (Figure 2). Volumes for the cohort ranged from 17% with normal PV, 23% mild-moderate PV expansion, to 60% with persisting severe (≥ +25%) PV expansion at hospital discharge. In a cohort subgroup of 62 patients where PV was measured at hospital admission and discharge there was no clinically significant association between change in weight and change in PV (r=0.327, p=0.01). Conclusions Diuresis-related changes in weight reflect clinical decongestion but do not consistently reflect better HF outcomes and, importantly, do not accurately reflect changes in intravascular volume. A basis for this discordance is the significant patient-to-patient variability in volume both at admission and discharge which confounds interpretation of surrogate metrics of decongestion. Failure to account for the marked heterogeneity in volume status contributes to the observed discordance between metrics of clinical decongestion and HF outcomes. Change in body weight is a common metric used to assess adequacy of decongestive therapy in patients hospitalized for heart failure (HF). However, the findings of clinical studies linking this metric to clinical decongestion and outcomes are mixed. We propose this reflects the failure to take into account biologic variability in intravascular volume status which would impact response to therapy. Data were prospectively collected in hospitalized patients requiring diuresis. Plasma volume (PV) was measured using I-131-labelled albumin indicator-dilution methodology. The cohort was stratified by median diuresis-related weight loss and analyzed for 1-year outcome of HF-related mortality or 1st re-hospitalization, and the relation of change in weight to change in PV admission to discharge. The cohort was composed of 138 patients with median weight loss of 6 (IQR -3.2, -8.1) kg during hospitalization (5 IQR 4, 6 days). Greater than median weight loss (Figure 1) did not result in better outcomes. At the time of hospital discharge the subgroup with greater weight loss (N=61) paradoxically demonstrated greater absolute (4.8±1.0 vs. 4.2±1.0 liters, p<0.001) and relative PV expansion(+44±29% vs. +33±23% above normal, p=0.023). Also demonstrated was marked heterogeneity in PV status in both subgroups (Figure 2). Volumes for the cohort ranged from 17% with normal PV, 23% mild-moderate PV expansion, to 60% with persisting severe (≥ +25%) PV expansion at hospital discharge. In a cohort subgroup of 62 patients where PV was measured at hospital admission and discharge there was no clinically significant association between change in weight and change in PV (r=0.327, p=0.01). Diuresis-related changes in weight reflect clinical decongestion but do not consistently reflect better HF outcomes and, importantly, do not accurately reflect changes in intravascular volume. A basis for this discordance is the significant patient-to-patient variability in volume both at admission and discharge which confounds interpretation of surrogate metrics of decongestion. Failure to account for the marked heterogeneity in volume status contributes to the observed discordance between metrics of clinical decongestion and HF outcomes.

The Acute Physiological Responses to Traditional vs. Practical Blood Flow Restriction Resistance Exercise in Untrained Men and Women.

This study compared the acute physiological responses of traditional and practical blood flow restriction resistance exercise (tBFR and pBFR, respectively) and high- and low-load resistance exercise without BFR (HL and LL, respectively), as well as the potential sex differences within the aforementioned exercise methods. Fourteen men and fifteen women randomly completed the following experimental conditions: (1) tBFR, consisting of four sets of 30-15-15-15 repetitions of the bilateral horizontal leg press and knee extension exercises, at 30% of one-repetition maximum (1-RM), with a 13.5 cm wide pneumatic cuff placed at the most proximal portion of each thigh and inflated to a pressure equivalent to 50% of the participant’s total occlusion pressure; (2) pBFR, which was the same as the tBFR condition, except that an elastic band wrapped around the proximal portion of each thigh at a tightness of 7 on a 0 to 10 perceived pressure scale was used to reduce blood flow; (3) LL, same as the tBFR and pBFR protocols, except that no BFR was applied; and (4) HL, consisting of 3 sets of 10 repetitions at 80% of 1-RM, with the same 1-min rest interval between sets and a 3-min rest period between exercises. At baseline, immediately post-, 5 min post-, and 15 min post-exercise, whole-blood lactate (WBL), indices of muscle swelling (muscle thickness and thigh circumference), hematocrit and plasma volume changes, were measured as well as superficial electromyography (sEMG) amplitude during exercise. There were no significant (p > 0.05) differences between the tBFR and pBFR exercise protocols for any of the physiological parameters assessed. However, significantly greater (p < 0.05) WBL and sEMG values were observed for HL compared to the remaining exercise conditions. Finally, males displayed greater WBL levels than females at 15 min post-exercise. Interestingly, males also displayed significantly (p < 0.05) greater sEMG amplitude than females within the low-load trials during leg press, but no significant (p < 0.05) sex differences were observed during knee extension. In conclusion, tBFR and pBFR seemed to be capable of inducing the same acute physiological responses. Furthermore, males displayed greater responses than females for some of the physiological parameters measured.

Changes in fluid and acid-base status of diarrheic calves on different oral rehydration regimens

The administration of oral rehydration solutions (ORS) is an effective method to treat dehydration and acidosis in calves suffering from diarrhea. The ORS can be prepared in water or milk. The aim of the present study was to elucidate how fluid and acid-base balance change after feeding milk compared with ORS prepared in water or milk to diarrheic calves. Calves (n = 30) with naturally acquired diarrhea were sequentially assigned in a 2:1 ratio to the following pretreatments: milk and water-ORS (pretreatment 1; n = 20 calves) or milk-ORS (pretreatment 2; n = 10 calves), respectively. The assignment was done on the day of diarrhea diagnosis. On d 3 ± 1 following assignment to pretreatment group, and after a fasting period of 9 h, diarrheic calves were subjected to the following treatments: 2 L of milk (pretreatment 1; n = 10 calves), water-ORS (pretreatment 1; n = 10 calves), or milk-ORS (pretreatment 2; n = 10 calves). Blood samples were taken before and at several time points until 6 h after feeding. Plasma protein, osmolality, and electrolytes were determined and a blood gas analysis was performed. Change in plasma volume was calculated according to plasma protein, and water intake during the experimental period was recorded. Plasma volume was increased 30 min after feeding water-ORS or milk but the increase was less pronounced after feeding milk compared with water-ORS. After feeding milk-ORS, no significant increase in plasma volume could be detected. Because of the pretreatment, plasma osmolality was higher in calves fed milk-ORS, but no change in plasma osmolality after feeding was detected. No difference in water consumption between the treatment groups was noted within the observed 6-h period. The pH was increased after feeding milk-ORS, whereas water-ORS and milk-feeding did not increase pH in blood. Pretreatment with milk-ORS resulted in higher baseline d-lactate concentration, but feeding milk-ORS reduced d-lactate values after feeding. In calves with diarrhea, plasma volume increased more quickly and to a greater extent after feeding water-ORS; thus, we recommend treating diarrheic calves with water-ORS before supplying milk. Nevertheless, diarrheic calves need milk to fulfill their energy needs. The administration of ORS in milk combined with free water access is more advisable than feeding milk exclusively because milk has no alkalinizing ability and contains less sodium. However, the effects of milk-ORS feeding on d-lactate levels in diarrheic calves need further elucidation.