On one method of numerical modeling of piezoconductive processes of a two-phase fluid system in a fractured-porous reservoir

A method of numerical modeling based on splitting by physical processes of two-phase fluid transfer in a formation with fractured-porous reservoirs is described. Reservoirs of this type have a natural fracture system and are described by the dual porosity model. A four-block mathematical model of the fluid redistribution between a pore-type matrix and a natural fracturing pattern is proposed and studied. The resulting system is complex and entails a number of difficulties associated with a large number of variables and the absence of important properties of a linearized system of equations, such as self-adjointness and symmetry, which are present in the description of piezoconductive processes. The complete splitting by physical processes is carried out to solve this problem. The resulting split model is differentially equivalent to the discrete initial balance equations of the system (conservation of the mass components of the fluids and the total energy of the system), written in divergent form. This approach is associated with a nonlinear approximation of the grid functions in time, which depends on the fraction of the volume occupied by the fluids in the pores, and is easy to implement.

Diagnostic Potential of Low Serum Platelet, Albumin and Prolong PT-INR for Overactive Bladder and Nocturia in Chronic Hepatitis-Related Liver Cirrhosis

Overactive bladder (OAB) is defined as urgency, usually with frequency, nocturia, and incontinence. Patients with liver cirrhosis often present with urinary complaints. The possible reason for this is fluid redistribution, which may induce OAB resulting from portal hypertension and ascites. We conducted this study to investigate predictors of OAB in cirrhotic patients. A total of 164 patients with chronic viral hepatitis-related liver cirrhosis were enrolled and 158 (96.3%) completed the Overactive Bladder Symptoms Score (OABSS) questionnaire. Age, severity of liver cirrhosis, comorbidities, serum sodium level, use of diuretics, body mass index and renal function were also recorded. In the study cohort, the prevalence of OAB was 31.01% and the prevalence of urge incontinence (OAB wet) was 18.3%. Patients with an urgency score ≥2 in OABSS had a significantly lower platelet level (p = 0.025) regardless of the use of diuretics. In addition, 98 patients (62%) with nocturia and 29 patients (18%) with urge incontinence had significantly lower levels of serum albumin (p = 0.028 and 0.044, respectively). In conclusion, patients with liver cirrhosis have a high prevalence of overactive bladder. A low platelet and low serum albumin level in these patients may be predictors for overactive bladder. And longer PT-INR is also a possible biomarker for nocturia.

Intraocular pressure and choroidal thickness respond differently to lower body negative pressure during spaceflight

Spaceflight associated neuro-ocular syndrome (SANS) develops during long-duration (>1 month) spaceflight presumably because of chronic exposure to a headward fluid shift that occurs in weightlessness. We aimed to determine whether reversing this headward fluid shift with acute application of lower body negative pressure (LBNP) can influence outcome measures at the eye. Intraocular pressure (IOP) and subfoveal choroidal thickness were therefore evaluated by tonometry and optical coherence tomography (OCT), respectively, in 14 International Space Station crewmembers before flight in the seated, supine, and 15° head-down tilt (HDT) postures and during spaceflight, without and with application of 25 mmHg LBNP. IOP in the preflight seated posture was 14.4 mmHg (95% CI, 13.5-15.2 mmHg) and spaceflight elevated this value by 1.3 mmHg (95% CI, 0.7-1.8 mmHg, P<0.001). Acute exposure to LBNP during spaceflight reduced IOP to 14.2 mmHg (95% CI, 13.4-15.0 mmHg), which was equivalent to that of the seated posture (P>0.99), indicating that venous fluid redistribution by LBNP can influence ocular outcome variables during spaceflight. Choroidal thickness during spaceflight (374 µm, 95% CI, 325-423 µm) increased by 35 µm (95% CI, 25-45 µm, P<0.001), compared to the preflight seated posture (339 µm, 95% CI, 289-388 µm). Acute use of LBNP during spaceflight did not affect choroidal thickness (381 µm, 95% CI, 331-430 µm, P=0.99). The finding that transmission of reduced venous pressure by LBNP did not decrease choroidal thickness suggests that engorgement of this tissue during spaceflight may reflect changes that are secondary to the chronic cerebral venous congestion associated with spaceflight.

Reappraisal of Factors Disturbing the Relationship between Body Water Volumes and Total Body Electrical Resistance in Patients on Hemodialysis

Background: Measurements of Total Body Electrical Resistance (TBER) are used to improve fluid balance management in patients on Hemodialysis (HD). This approach is based on the inverse relation that exists between TBER and body water volumes. Interpretation errors may occur if TBER measurements are affected by factors that are not related to changes in body water. Aim of this paper was to provide an overview of the methodological artifacts commonly encountered in a clinical setting, and to strengthen current evidence of their disturbing effects by performing additional experiments. Methods: This study includes an analysis of available literature data, supplemented with additional experiments in healthy adults and patients. A cutoff of 2.7% was used to classify changes in TBER as significant within individual subjects. Results: Electrode position, electrode interference, differences of measurements performed at the right or left side of the body, presence of orthopedic prosthesis located in the limbs, fluid redistribution induced by longterm changes in body position, and electrolyte abnormalities were the main disturbing factors that can induce a significant change in TBER. Other factors either had no significant disturbing effect or could be easily avoided. Conclusion: TBER measurements require a high degree of standardization to minimize interpretation errors.

Comparing Lung CT in COVID-19 Pneumonia and Acute Heart Failure: An Imaging Conundrum

Background: Lung CT provides an effective modality to evaluate patients with suspected COVID-19. However, overlapping imaging findings with cardiogenic pulmonary oedema have been reported. Reports comparing lung CT features of these diseases have not been elaborated. Thus, we aimed to investigate these gaps in the knowledge regarding low-dose lung CT features of patients with COVID-19 pneumonia with those with acute heart failure (HF). Methods: This retrospective analysis enrolled hospitalized patients with COVID-19 (n=10) and acute heart failure (n=9) that exclusively underwent low-dose lung CT scans within 24-hours of admission. Clinical and lung CT characteristics were collected and analysed. Results: Ground-glass-opacities (GGO) appearance has been recorded in all subjects in HF and COVID-19 group. There was no significant statistical difference between the two groups for rounded morphology, consolidation, crazy paving pattern, lesion distribution, parenchymal band (P&gt; 0.05). However, diffuse lesions were more frequent in HF cases (55.6% vs. 0%) than in COVID-19 pneumonia, which had predominantly multifocal pattern. Notably, CT images in HF patients were more likely to have signs of interstitial tissue thickening such as the interlobular septums, fissures and peribronchovascular interstitium (55.6% vs 0%, 88.9% vs 20% and 44.4% vs 0%,respectively), as well as cardiomegaly (77.8% vs 0%), increased artery to bronchus ratio (55.6% vs 0%), and pleural effusions (77.8% vs 0%). Conclusions: Major overlaps of lung CT imaging features existed between COVID-19 pneumonia and acute HF cases. However, signs of fluid redistribution are clues that favour HF over COVID-19 pneumonia.

FEATURES OF FLUID REDISTRIBUTION DURING GOAL-DIRECTED INFUSION THERAPY OF HIGH SURGICAL RISK PATIENTS IN URGENT SURGERY

One of the basic components of intensive treatment of patients with an urgent abdominal pathology is perioperative infusion therapy. To analyze the perioperative dynamics of the water sectors of a body in the patients with a high surgical risk with acute abdominal pathology, a targeted regimen of infusion therapy was used to examine 35 patients. Perioperative targeted infusion therapy was carried out with balanced crystalloid solutions. With the non−invasive bioelectric rheography, the indices of water sectors of a body were studied. On the first day, the extracellular sector volume overflow was established due to an increase in interstitial volume. From the second day, the excess volumes of intravascular fluid and plasma were determined. On the third day there was a deficit of all the studied indices. On the fifth day of the post−surgery period, volumetric depletion of mild degree was noted. From the seventh to the tenth days, all the studied parameters to normal were reliably restored. A targeted regimen of infusion therapy in such patients was concluded to correct a moderate volume depletion on the tenth day after surgery by an excessive increase in plasma volume after six hours of treatment, the development of interstitial edema in the first two days, and the formation of mild volumetric depletion from third to seventh day. Key words: water sectors, goal−direct infusion therapy, depletion, urgent surgery, high surgical risk.