Volume Shifts Research Articles

Estimation of plasma volume in patients presenting with acute decompensated heart failure using Kaplan – Hakim formula and correlation of plasma volume shift with outcomes

Estimation of plasma volume in patients presenting with acute decompensated heart failure using Kaplan – Hakim formula and correlation of plasma volume shift with outcomes

Correlation between Hypervolemia, Left Ventricular Hypertrophy and Fibroblast Growth Factor- 23 in Prevalent Hemodialysis Patients

Abstract Background Patients with end-stage renal disease are exposed to extreme volume shifts and thereby cardiovascular strain as a consequence of interdialytic weight gain, fluid removal during hemodialysis and also chronic fluid overload. In long-term hemodialysis patients, higher IDWG (interdialytic weight gain) is associated with poor survival and increased cardiovascular death. Patients with the lowest interdialytic fluid retention have the greatest survival. It was found that increased interdialytic volume load is associated with increased both LVMI and FGF-23 level. Objective To evaluate correlation between hypervolemia, left ventricular hypertrophy and FGF-23 in prevalent hemodialysis patients. Patients and Methods This cross sectional study was conducted in Ain shams university hospital and Al Agoza hospital, on 60 prevalent hemodialysis patients.Three patient died during the study. Results FGF-23 had a positive correlation with (weight gain, (PO4)3-, PTH, IVS, PW and LVMI). Conclusion FGF-23 might be a marker of volume overload and LVH in ESRD patients, as it positively correlated with (weight gain, IVS, PW and LVMI). FGF-23 is a marker of bone diseases, as it positively correlated with (PO4)3- and PTH. Volume overload has a negative impact on morbidity and mortality in ESRD patients.

Separating ventricular activity in thoracic EIT using 4D image-based FEM simulations

Abstract One challenge in central hemodynamic monitoring based on electrical impedance tomography (EIT) is to robustly detect ventricular signal components and the corresponding EIT image region without external monitoring information. Current stimulation and voltage measurement of EIT were simulated with finite element porcine torso models in presence of a multitude of thoracic blood volume shifts. The simulated measurement data was examined for linear dependence on changes in stroke volume. Based on the results the EIT measurement information regarding stroke volume changes is sparse

The effect of music on body sway when standing in a moving virtual environment.

Movement of the visual environment presented through virtual reality (VR) has been shown to invoke postural adjustments measured by increased body sway. The effect of auditory information on body sway seems to be dependent on context with sounds such as white noise, tones, and music being used to amplify or suppress sway. This study aims to show that music manipulated to match VR motion further increases body sway. Twenty-eight subjects stood on a force plate and experienced combinations of 3 visual conditions (VR translation in the AP direction at 0.1 Hz, no translation, and eyes closed) and 4 music conditions (Mozart's Jupiter Symphony modified to scale volume at 0.1 Hz and 0.25 Hz, unmodified music, and no music) Body sway was assessed by measuring center of pressure (COP) velocities and RMS. Cross-coherence between the body sway and the 0.1 Hz and 0.25 Hz stimuli was also determined. VR translations at 0.1 Hz matched with 0.1Hz shifts in music volume did not lead to more body sway than observed in the no music and unmodified music conditions. Researchers and clinicians may consider manipulating sound to enhance VR induced body sway, but findings from this study would not suggest using volume to do so.

Nickelate Superconductivity without Rare-Earth Magnetism: (La,Sr)NiO2.

The occurrence of unconventional superconductivity in cuprates has long motivated the search for manifestations in other layered transition metal oxides. Recently, superconductivity is found in infinite-layer nickelate (Nd,Sr)NiO2 and (Pr,Sr)NiO2 thin films, formed by topotactic reduction from the perovskite precursor phase. A topic of much current interest is whether rare-earth moments are essential for superconductivity in this system. In this study, it is found that with significant materials optimization, substantial portions of the La1- x Srx NiO2 phase diagram can enter the regime of coherent low-temperature transport (x= 0.14 - 0.20), with subsequent superconducting transitions and a maximum onset of ≈9 K at x= 0.20. Additionally, the unexpected indication of a superconducting ground state in undoped LaNiO2 is observed, which likely reflects the self-doped nature of the electronic structure. Combining the results of (La/Pr/Nd)1- x Srx NiO2 reveals a generalized superconducting dome, characterized by systematic shifts in the unit cell volume and in the relative electron-hole populations across the lanthanides.

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 resting, 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). CONCLUSIONS: 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.

Reservoir Simulation Analysis of Pressure Depletion Performance in Gas-Condensate Reservoirs: Black-Oil and Compositional Approaches

Pressure depletion in gas-condensate reservoirs create two-phase flow. It is pertinent to understand the behavior of gas-condensate reservoirs as pressure decline in order to develop proper producing strategies that would increase gas and condensate productivity.&#x0D; Eclipse 300 was used to simulate gas-condensate reservoirs, a base case model was created using both black-oil and compositional models. The effects of three Equation of States (EOS) incorporated into the models were analysed and condensate dropout effect on relative permeability was studied.&#x0D; Analysis of various case models showed that, gas production was maintained at 500MMSCF/D for about 18 and 12 months for black-oil and compositional models, respectively. However, the compositional model revealed that condensate production began after a period of two months at 50MSTB/D whereas for the black oil model, condensate production began immediately at 32MSTB/D. Comparison of Peng-Robinson EOS, Soave-Redlich-Kwong EOS and Schmidt Wenzel EOS gave total estimates of condensate production as 19MMSTB, 15MMSTB and 9MMSTB and initial values of gas productivity index as 320, 380 and 560, respectively. The results also showed that as condensate saturation increased, the relative permeability of gas decreased from 1 to 0 while the relative permeability of oil increased from 0.15 to 0.85.&#x0D; The reservoir simulation results showed that compositional model is better than black-oil model in modelling for gas-condensate reservoirs. Optimal production was obtained using 3-parameter Peng-Robinson and Soave-Redlich-Kwong EOS which provide a molar volume shift to prevent an underestimation of liquid density and saturations. Phase behaviour and relative permeability affect the behaviour of gas-condensate reservoirs.

Physiological significance of pre- and post-ejection left ventricular tissue velocities and relations to mitral and aortic valve closures.

Tissue Doppler shows short duration velocity spikes during pre- and post-ejection (protodiastole). They have been assumed to be isovolumic contraction and relaxation movements, but this is not in accordance with newer studies. We examined 22healthy volunteers. Valve closures and openings were determined from spectral Doppler from LVOT and mitral inflow and transferred to colour tissue Doppler recordings for comparison with tissue velocities, colour M-mode and strain rate (SR). Pre-ejection positive velocity spikes were simultaneous in both walls, starting ca. 24.8±10.1ms after start QRS, duration 51.5±10.8ms, ending 10.2±11.5ms after mitral valve closure (MVC) (p<0.001). There were corresponding colour tracings and negative strain rate. Protodiastolic lengthening was predominant in the septum. Negative velocity spikes had a duration of 35.5±10.7ms, ending 9.5±14.7ms after aortic valve closure (AVC, p<0.001) in septum. During isovolumic relaxation, strain rate showed apical lengthening (Peak SR-0.72±0.50s-1 ) and basal shortening (Peak SR 0.44±0.63s-1 ). Electromechanical activation of the LV is simultaneous in septum and lateral wall, occurs before MVC, is terminated by MVC itself and is thus not isovolumic. Protodiastole is a short event of lengthening, predominantly in the septum. It may be the mechanism for valve closure and ends by AVC itself. Isovolumic relaxation occurs after this velocity spike, and is characterized by elongation of the apex, shortening of the base, thus showing a volume shift from base towards apex.

Is Call Karma Real? Resident After-Hours On-Call Imaging at the University of Saskatchewan: An Assessment of Call Volumes Including Inter-Resident Variability.

Quantify resident caseload during call and determine if there are consistent differences in call volumes for individuals or resident subgroups. Accession codes for after-hours computed tomography (CT) cases dictated by residents between July 1, 2012 and January 9, 2017 were reviewed. Case volumes by patient visits and body regions scanned were determined and categorized according to time period, year, and individual resident. Mean shift Relative Value Units (RVUs) were calculated by year. Descriptive statistics, linear mixed modeling, and linear regression determined mean values, differences between residents, associations between independent variables and outcomes, and changes over time. Consistent differences between residents were assessed as a measure of good or bad luck / karma on call. During this time there were 23,032 patients and 30,766 anatomic regions scanned during 1,652 call shifts among 32 residents. Over the whole period, there were on average 10.6 patients and 14.3 body regions scanned on weekday shifts and 22.3 patients and 29.4 body regions scanned during weekend shifts. Annually, the mean number of patients, body regions, and RVUs scanned per shift increased by an average of 0.2 (1%), 0.4 (2%), and 1.2 (5%) (all p < 0.05) respectively in regression models. There was variability in call experiences, but only 1 resident had a disproportionate number of higher volume calls and fewer lower volume shifts than expected. Annual increases in scan volumes were modest. Although residents' experiences varied, little of this was attributable to consistent personal differences, including luck or call karma.

Effect of Exercise-Induced Reductions in Blood Volume on Cardiac Output and Oxygen Transport Capacity.

We wanted to demonstrate the relationship between blood volume, cardiac size, cardiac output and maximum oxygen uptake (O2max) and to quantify blood volume shifts during exercise and their impact on oxygen transport. Twenty-four healthy, non-smoking, heterogeneously trained male participants (27 ± 4.6 years) performed incremental cycle ergometer tests to determine O2max and changes in blood volume and cardiac output. Cardiac output was determined by an inert gas rebreathing procedure. Heart dimensions were determined by 3D echocardiography. Blood volume and hemoglobin mass were determined by using the optimized CO-rebreathing method. The O2max ranged between 47.5 and 74.1 mL⋅kg–1⋅min–1. Heart volume ranged between 7.7 and 17.9 mL⋅kg–1 and maximum cardiac output ranged between 252 and 434 mL⋅kg–1⋅min–1. The mean blood volume decreased by 8% (567 ± 187 mL, p = 0.001) until maximum exercise, leading to an increase in [Hb] by 1.3 ± 0.4 g⋅dL–1 while peripheral oxygen saturation decreased by 6.1 ± 2.4%. There were close correlations between resting blood volume and heart volume (r = 0.73, p = 0.002), maximum blood volume and maximum cardiac output (r = 0.68, p = 0.001), and maximum cardiac output and O2max (r = 0.76, p < 0.001). An increase in maximum blood volume by 1,000 mL was associated with an increase in maximum stroke volume by 25 mL and in maximum cardiac output by 3.5 L⋅min–1. In conclusion, blood volume markedly decreased until maximal exhaustion, potentially affecting the stroke volume response during exercise. Simultaneously, hemoconcentrations maintained the arterial oxygen content and compensated for the potential loss in maximum cardiac output. Therefore, a large blood volume at rest is an important factor for achieving a high cardiac output during exercise and blood volume shifts compensate for the decrease in peripheral oxygen saturation, thereby maintaining a high arteriovenous oxygen difference.

Glyceryl trinitrate for the treatment of ischaemic stroke: Determining efficacy in rodent and ovine species for enhanced clinical translation

Hypertension is a leading risk factor for death and dependency after ischaemic stroke. However, administering anti-hypertensive medications post-stroke remains contentious with concerns regarding deleterious effects on cerebral blood flow and infarct expansion. This study sought to determine the effect of glyceryl trinitrate (GTN) treatment in both lissencephalic and gyrencephalic pre-clinical stroke models. Merino sheep underwent middle cerebral artery occlusion (MCAO) followed by GTN or control patch administration (0.2 mg/h). Monitoring of numerous physiologically relevant measures over 24 h showed that GTN administration was associated with decreased intracranial pressure, infarct volume, cerebral oedema and midline shift compared to vehicle treatment (p < 0.05). No significant changes in blood pressure or cerebral perfusion pressure were observed. Using optical imaging spectroscopy and laser speckle imaging, the effect of varying doses of GTN (0.69–50 µg/h) on cerebral blood flow and tissue oxygenation was examined in mice. No consistent effect was found. Additional mice undergoing MCAO followed by GTN administration (doses varying from 0–60 µg/h) also showed no improvement in infarct volume or neurological score within 24 h post-stroke. GTN administration significantly improved numerous stroke-related physiological outcomes in sheep but was ineffective in mice. This suggests that, whilst GTN administration could potentially benefit patients, further research into mechanisms of action are required.

Hypertrophic Obstructive Cardiomyopathy: Discrepancy Between Hemodynamic Measurements in the Cardiac Laboratory and Operating Room Is to Be Expected

It is not uncommon to observe some discrepancy in hemodynamic values characterizing left ventricular outflow tract (LVOT) obstruction preoperatively and in the operating room in patients with hypertrophic obstructive cardiomyopathy. Interpretation of this discrepancy can be challenging. To clarify the extent of the discrepancy, the authors compared hemodynamic variables in patients undergoing septal myectomy at the time of preoperative and intraoperative evaluation. Retrospective study. Single academic medical center. Medical records review, study group-173 patients. While there was no statistically significant difference in resting peak LVOT gradients by preoperative transthoracic echocardiography (TTE) compared to intraoperative transesophageal echocardiography (46 mmHg [19-87 mmHg] v 36 mmHg [16-71 mmHg], p=0.231), the former were higher compared to direct needle-resting LVOT gradient measurements before myectomy (49 mmHg [19-88 mmHg] v 32 mmHg [14-67 mmHg], p=0.0022). The prevalence of systolic anterior motion was high (94.6% v 91.6%, P=1.000) both on pre- and intraoperative evaluation. The incidence of moderate/severe mitral was higher intraoperatively (p < 0.0001). Pulmonary artery systolic pressures measured by pulmonary artery catheter provided higher values compared to preoperative TTE estimate (39 mmHg [34-45 mmHg] v 34 mmHg [28-41 mmHg], p < 0.0001). Discrepancy between hemodynamic measurements in the cardiac laboratory and operating room is common and generally should not affect planned patients' care. These changes in hemodynamics might be explained by preoperative fasting, anesthetic agents, volume shifts while supine, and positive-pressure ventilation, as well as the difference in measurement techniques.

Supine Pseudoanemia in Hospitalized Patients

Hemoglobin levels might be subject to postural effects — lower when supine and higher when upright — because of shifts in plasma volume to the vascular

Compositional modeling of multicomponent gas injection into saline aquifers with the MUFITS simulator

Reservoir simulations of the co-injection of natural gas, carbon dioxide, and other non-condensable gases into saline aquifers are in demand in many areas of subsurface utilization, ranging from excess energy and greenhouse gas storage to the substitution of cushion gas with CO2. We aim at extending our reservoir simulator MUFITS for modeling flows in porous media related to these applications. For the accurate prediction of phase equilibria in aqueous systems, we implement a modified method of Søreide and Whitson in the compositional module of the software. The modified equation of state (EoS) involves the most recent literature data on the binary interaction coefficients and several new correlations for volume shifts to improve the accuracy of the EoS for predicting the partial volume of dissolved gases. All the aggregated and developed correlations are built into the simulator to facilitate its usage by the scientific community. The extended software is validated against a benchmark study of pure CO2 injection into a saline aquifer. Furthermore, two more complicated studies concerning the co-injection of several gases are conducted to demonstrate the potential application areas of MUFITS. First, we simulate the injection of impure carbon dioxide into an aquifer and briefly discuss the influence of N2 impurity on the propagation of the gas plume. We show that the plume is significantly wider in the case of impure CO2 injection. Second, we simulate the injection of supercritical CO2 into a synthetic natural gas storage reservoir to substitute cushion gas. We show that the mechanical dispersion can cause a rapid CO2 spread into the wells used for natural gas production.

Mitral prolapsing volume is associated with increased cardiac dimensions in patients with mitral annular disjunction.

IntroductionIn patients with mitral annular disjunction (MAD), it can be difficult to assess the severity of mitral regurgitation (MR), as they present with a prolapsing volume (i.e. volume resulting from mitral valve prolapse, blood volume shift) rather than a regurgitant jet. The influence of the mitral prolapsing volume (MPV) on cardiac dimensions is unknown. We hypothesised that the severity of MR is underestimated in these patients. Our aim was to measure MPV and to investigate its influence on cardiac dimensions in patients with MAD.MethodsWe retrospectively included 131 consecutive patients with MAD from our institution’s echocardiographic database. Transthoracic echocardiography was used to assess MPV. Additionally, we established a control group of 617 consecutive patients with degenerative mitral valve disease and performed propensity score matching.ResultsMedian MPV in the MAD group was 12 ml. MPV was an independent predictor for left ventricular end-diastolic (LVEDD) and end-systolic diameter (LVESD) and left atrial volume (all p < 0.001). In patients with large prolapsing volumes (> 15 ml), LVEDD (56 ± 6 mm vs 51 ± 6 mm, p < 0.001), LVESD [38 mm (34–41) vs 34 mm (31–39), p < 0.01] and left atrial volume [105 ml (86–159) vs 101 ml (66–123), p = 0.04] were significantly increased compared to matched patients with degenerative mitral valve disease and similarly assessed severity of MR.ConclusionDue to a volume shift based on the MPV rather than an actual regurgitant jet, MR severity cannot be assessed adequately in MAD patients. Increased MPV induces ventricular and atrial enlargement. These findings warrant future studies to focus on MPV as an additional parameter for assessment of the severity of MR in MAD patients.Supplementary InformationThe online version of this article (10.1007/s12471-021-01575-6) contains supplementary material, which is available to authorized users.

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.

Altered Fibrinolysis during and after Surgery.

Major surgery induces hemostatic changes related to surgical stress, tissue destruction, and inflammatory reactions. These changes involve a shift of volume from extravascular space to intravascular and interstitial spaces, a "physiologic" hemodilution of coagulation proteins, and an increase of plasmatic fibrinogen concentration and platelets. Increases in fibrinogen and platelets together with a simultaneous dilution of pro- and anticoagulant factors and development of a hypofibrinolytic status result in a postoperative hypercoagulable state. This profile is accentuated in more extensive surgery, but the balance can shift toward hemorrhagic tendency in specific types of surgeries, for example, in prolonged cardiopulmonary bypass or in patients with comorbidities, especially liver diseases, sepsis, and hematological disorders. Also, acquired coagulopathy can develop in patients with trauma, during obstetric complications, and during major surgery as a result of excessive blood loss and subsequent consumption of coagulation factors as well as hemodilution. In addition, an increasing number of patients receive anticoagulants and antiplatelet drugs preoperatively that might influence the response to surgical hemostasis. This review focuses on those situations that may change normal hemostasis and coagulation during surgery, producing both hyperfibrinolysis and hypofibrinolysis, such as overcorrection with coagulation factors, bleeding and hyperfibrinolysis that may occur with extracorporeal circulation and high aortic-portal-vena cava clamps, and hyperfibrinolysis related to severe maintained hemodynamic disturbances. We also evaluate the role of tranexamic acid for prophylaxis and treatment in different surgical settings, and finally the value of point-of-care testing in the operating room is commented with regard to investigation of fibrinolysis.

Delta-Loop-Stitch: Three-Point Fixation for Combined Radial and Tangential Capsular Shift for the Treatment of Multidirectional Instability of the Shoulder and Hyperlaxity

Multidirectional shoulder instability and hyperlaxity can be treated with arthroscopic shoulder stabilization and capsular shift. In these patients, the joint capsule often becomes the weak link in terms of pullout strength and cutting through of the used sutures, which can further be compromised by reduced quality of the capsular tissue.The described delta-loop-stitch combines a loop stitch through the capsule with a 3-point-fixation to the intact labrum thus distributing the load and reducing the risk of failure of the fixation. The suture knots are directed under the joint capsule away from the articulating surfaces to reduce the risk of iatrogenic lesions of the articular cartilage.The circumferential application of the delta-loop-stitch allows a sufficient capsular shift that combines a radial and tangential shift and reduction of the overall joint volume that can be adjusted to the patient’s individual situation and the surgeon’s preference.

Estimating polystyrene equation of state (EOS) parameters using the cloud and critical points of polystyrene + hydrocarbon mixtures*

AbstractThree polystyrene parameters for the modified Sanchez‐Lacombe equation of state were estimated by performing a correlation of the cloud and critical point data for six well defined polystyrene + hydrocarbon mixtures. The volume shift, a fourth parameter, was adjusted to the polystyrene pressure‐volume‐temperature (PVT) data. A parameterization of the modified Sanchez‐Lacombe equation of state is used to estimate the hydrocarbon parameters given their critical temperature, critical pressure, and acentric factor, but these properties are not available for the polymer. The original polystyrene parameters estimated solely on the pure component PVT data results have difficulty representing the slope and curvature of the cloud points of binary polystyrene + hydrocarbon mixtures. A previous technique for adjusting one of the polystyrene parameters to match the cloud points with the remainder fit to the PVT data results in an improved match over the pure component PVT data alone. Adjusting three polystyrene parameters can better match the cloud points of a binary polystyrene + hydrocarbon mixture, while only increasing the absolute average deviation in pure polystyrene density by 0.07%. The polystyrene parameters obtained by fitting the cloud points were used to correlate the bubble points of polystyrene in other solvents.

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.