Changes In Venous Pressure Research Articles

A new method to predict return of spontaneous circulation by peripheral intravenous analysis during cardiopulmonary resuscitation: a rat model pilot study.

Enhancing venous return during cardiopulmonary resuscitation (CPR) can lead to better hemodynamics and improved outcome after cardiac arrest (CA). Peripheral Intravenous Analysis (PIVA) provides feedback on venous flow changes and may indicate an increase in venous return and cardiac output during CPR. We hypothesize PIVA can serve as an early indicator of increased venous return, preceding end-tidal CO2 (etCO2) increase, before the return of spontaneous circulation (ROSC) in a rat model of CA and CPR. Eight male Wistar rats were intubated and ventilated, and etCO2 was measured. Vessels were cannulated in the tail vein, femoral vein, femoral artery, and central venous and connected to pressure transducers. Ventilation was discontinued to achieve asphyxial CA. After 8min, CPR began with ventilation, epinephrine, and automated chest compressions 200 times per minute until mean arterial pressure increased to 120mmHg. Waveforms were recorded and analyzed. PIVA was calculated using a Fourier transformation of venous waveforms. Data are mean ± SE. Maximum PIVA values occurred in the tail vein 34.7 ± 2.9s before ROSC, with subsequent PIVA peaks in femoral vein and centrally at 30.9 ± 5.4 and 25.1 ± 5.0s, respectively. All PIVA peaks preceded etCO2 increase (21.5 ± 3.2s before ROSC). PIVA consistently detected venous pressure changes prior to changes in etCO2. This suggests that PIVA has the potential to serve as an important indicator of venous return and cardiac output during CPR, and also as a predictor of ROSC.

Dynamic Narrowing of the Diaphragmatic Vena Cava in Ovis aries.

Dorset sheep (Ovis aries) are common models in translational cardiovascular research due to physiologic and anatomic similarities to humans. While employing ovine subjects to study single-ventricle physiology, we repeatedly observed position-based changes in central venous pressure (CVP) which could not be explained by hydrostatic (gravitational) effects. Inferior vena cava (IVC) narrowing or compression has been demonstrated in numerous species, and we hypothesised that this phenomenon might explain our observations in O. aries. This study aimed to characterise position-dependent morphology of the IVC in O. aries using catheter-based hemodynamic and dimensional measurements, three-dimensional MRI reconstruction and histological analysis. Baseline measurements revealed a significant reduction in IVC dimensions at the level of the diaphragm (dVC) compared to the abdominal vena cava (aVC) and thoracic vena cava (tVC). We also observed a transdiaphragmatic pressure gradient along the IVC, with higher pressures in the aVC compared to the tVC. We found that variation of position and fluid status altered IVC haemodynamics. Histological data showed variable muscularity along the length of the IVC, with greater smooth muscle content in the aVC than the tVC. These findings will improve understanding of baseline ovine physiology, help refine experimental protocols and facilitate the translation of findings to the clinic.

Regional heterogeneity of cerebral blood flow immediately after the onset of ventricular pacing in anesthetized rats.

Selective distribution of cerebral blood flow (CBF) to vital brain regions likely occurs during rapid severe hypotension caused by tachyarrhythmia, but has not yet been demonstrated. In this study, we aimed to test the hypothesis that CBF is differentially preserved between brain regions depending on the degree of hypotension. In anesthetized rats, CBF was measured in the motor cortex (MC), medial prefrontal cortex, amygdala, thalamus, dorsal hypothalamus, hippocampus, ventral tegmental area, dorsolateral periaqueductal gray (dlPAG), and parabrachial nucleus (PB) by using laser-Doppler flowmetry. Ventricular pacing was performed for 30 s at 550-800 beats/min. The cerebrovascular CO2 response time and reactivity were evaluated during 5% CO2 exposure. During 1-4 s of ventricular pacing, mean arterial pressure (MAP) rapidly decreased, with minor changes in central venous and intracranial pressures. CBF was relatively well maintained in brain regions other than the MC (Ps ≤ 0.012) when moderate hypotension occurred (-34 mmHg ≤ ΔMAP ≤ -15 mmHg), whereas severe hypotension (-54 mmHg ≤ ΔMAP ≤ -35 mmHg) induced selective CBF distribution to regions other than the MC, thalamus, and dlPAG. The cerebrovascular CO2 response time/reactivity was rapid or high in the thalamus, dlPAG, and PB, which almost completely differed from the brain regions in which CBF was relatively maintained during pacing-induced severe hypotension. These results suggest that regional heterogeneity of CBF arises depending on the degree of tachyarrhythmia-induced hypotension. Clarifying the mechanisms and functions of CBF maintenance would be beneficial to syncope and cerebral ischemia management in patients with arrhythmia.

Influence between Body Mass Index and Blood Pressure With Results of Urine Protein Examination in Pregnant Women at Bangkalan Health Center

Background: Preeclampsia is an increase in blood pressure that occurs after the 20th week of gestation. Until now, the exact cause of preeclampsia is not known. During the second trimester of pregnancy the pressure in the renal veins (renal venous pressure) changes and increases. Increased renal venous pressure causes proteinuria, especially in the orthostatic position, which causes a slightly greater change in kidney size. Purpose: The aim of this study was The Relationship Between Body Mass Index And Blood Pressure With Results Of Urine Protein Examination In Pregnant Women At Bangkalan Health Center. Methods: Analytical Research Design with a cross sectional approach. Independent variable Body Mass Index and Blood Pressure, dependent variable results of urine protein examination. The sample of this study were 210 pregnant women who carried out Integrated ANC at the Bangkalan Health Center, the sampling technique used Simple random sampling. Secondary data collection by looking at medical record data, statistical tests using Rank Spearman. Results: Based on statistical tests using Rank-Spearman, the results showed ρ value (0.024) <α (0.05) indicating that there is a relationship between Body Mass Index and urine protein examination results. The results of the study ρ value (0.020) <α (0.05) there is a relationship between blood pressure and the results of urine protein examination. Conclusion: Detection of proteinuria is very important in the diagnosis and treatment of hypertension in pregnancy. Proteinuria is the last symptom to appear in patients with preeclampsia.

Effects of neuromuscular electrical stimulation, light intensity walking and a seated exercise trainer on venous return in healthy young adults: a quasi-experimental crossover study

Background/Aims The growing prevalence of sedentary behaviour across the life course is linked to an increased risk of chronic venous disease and related mortality, warranting the need for non-invasive interventions to improve blood flow and lower extremity function. The aim of this study was to investigate the change in venous blood flow, heart rate and blood pressure after 8 minutes of using the Leeper device, Circulation Booster and light intensity walking. Methods A quasi-experimental crossover study involving 11 participants (eight women, three men, mean age 23.91 years, standard deviation 1.04 years) was conducted using Leeper and Circulation Booster devices and light intensity walking. During each intervention, participants exercised for 8 minutes, and blood flow was recorded at 0, 4 and 8 minutes. Heart rate and blood pressure were recorded at 0 and 8 minutes. Blood flow was the primary outcome measure, and heart rate and blood pressure were secondary outcomes. Participants rested for 10 minutes between exercise. A two-way repeated measures analysis of variance was used to analyse the effect of intervention and time on blood flow, blood pressure and heart rate. Results There was no significant interaction between intervention and time on blood flow (P=0.180) indicating that blood flow did not change over time depending on intervention. There was no significant main effect of time on blood flow (P=0.206), indicating that no intervention caused a significant increase or decrease in blood flow after 8 minutes of exercise. Conclusions The interventions involving the Leeper and Circulation Booster devices and light intensity walking did not appear to significantly increase blood flow in young adults. Further studies involving participants from older age groups and those with pathological interventions are warranted to examine the potential effectiveness of these interventions. Implications for practice The findings may assist with the advice that allied health professionals provide regarding the use of seated exercise trainers and EMS devices and their ability to influence changes in blood flow.

On the spinal venous sinus of Alligator mississippiensis.

The epidural space of the American alligator (Alligator mississippiensis) is largely filled by a continuous venous sinus. This venous sinus extends throughout the trunk and tail of the alligator, and is continuous with the dural sinuses surrounding the brain. Segmental spinal veins (sl) link the spinal venous sinus (vs) to the somatic and visceral venous drainage. Some of these sl, like the caudal head vein along the occipital plate of the skull, are enlarged, suggesting more functional linkage. No evidence of venous valves or external venous sphincters was found associated with the vs; the relative scarcity of smooth muscle in the venous wall of the sinus suggests limited physiological regulation. The proatlas (pr), which develops between the occipital plate and C1 in crocodylians, is shaped like a neural arch and is fused to the dorsal surface of the vs. The present study suggests that the pr may function to propel venous blood around the brain and spinal cord. The vs effectively encloses the spinal dura, creating a tube-within-a-tube system with the (smaller volume) spinal cerebrospinal fluid (CSF). Changes in venous blood pressure, as are likely during locomotion, would impact dural compliance and CSF pressure waves propagating along the spinal cord.

Estimating the change in pleural pressure using the change in central venous pressure in various clinical scenarios: a pig model study

BackgroundWe have previously reported a simple correction method for estimating pleural pressure (Ppl) using central venous pressure (CVP). However, it remains unclear whether this method is applicable to patients with varying levels of intravascular volumes and/or chest wall compliance. This study aimed to investigate the accuracy of our method under different conditions of intravascular volume and chest wall compliance.ResultsTen anesthetized and paralyzed pigs (43.2 ± 1.8 kg) were mechanically ventilated and subjected to lung injury by saline lung lavage. Each pig was subjected to three different intravascular volumes and two different intraabdominal pressures. For each condition, the changes in the esophageal pressure (ΔPes) and the estimated ΔPpl using ΔCVP (cΔCVP-derived ΔPpl) were compared to the directly measured change in pleural pressure (Δd-Ppl), which was the gold standard estimate in this study. The cΔCVP-derived ΔPpl was calculated as κ × ΔCVP, where “κ” was the ratio of the change in airway pressure to the change in CVP during the occlusion test. The means and standard deviations of the Δd-Ppl, ΔPes, and cΔCVP-derived ΔPpl for all pigs under all conditions were 7.6 ± 4.5, 7.2 ± 3.6, and 8.0 ± 4.8 cmH2O, respectively. The repeated measures correlations showed that both the ΔPes and cΔCVP-derived ΔPpl showed a strong correlation with the Δd-Ppl (ΔPes: r = 0.95, p < 0.0001; cΔCVP-derived ΔPpl: r = 0.97, p < 0.0001, respectively). In the Bland–Altman analysis to test the performance of the cΔCVP-derived ΔPpl to predict the Δd-Ppl, the ΔPes and cΔCVP-derived ΔPpl showed almost the same bias and precision (ΔPes: 0.5 and 1.7 cmH2O; cΔCVP-derived ΔPpl: − 0.3 and 1.9 cmH2O, respectively). No significant difference was found in the bias and precision depending on the intravascular volume and intraabdominal pressure in both comparisons between the ΔPes and Δd-Ppl, and cΔCVP-derived ΔPpl and Δd-Ppl.ConclusionsThe CVP method can estimate the ΔPpl with reasonable accuracy, similar to Pes measurement. The accuracy was not affected by the intravascular volume or chest wall compliance.

Effects of low-load blood flow restriction on the venous system in comparison to traditional low-load and high-load exercises.

Purpose: Blood-Flow-Restriction (BFR) training provides the ability to achieve hypertrophy effects even though only light mechanical loads are applied. However, its impact on venous pressures and function are still unknown. Therefore, the present study investigates the influence of BFR-training on intravascular venous pressure and venous function in comparison to control exercises with low or high mechanical loads. Methods: In a randomized cross-over design, ten healthy men (27.6 ± 6.4 years) underwent three trials of unilateral knee-extensor exercise with three different training protocols, low-load- (LL-RT, 30% of the individual 1-repetition-maximum, 1RM), low-load BFR- (LL-BFR-RT, 30% 1RM, 50% limb occlusion pressure, LOP) and high-load resistance exercise (HL-RT, 75% 1RM). Exercise protocols contain about four sets of knee extension exercise (Range-of-Motion: 0-0-95°), separated by 60s of rest. Each set was performed until volitional muscle failure. For analysis of changes in intravascular venous pressures and venous function, a venous catheter was placed at the exercising leg before each trial. Whereas venous pressures were recorded throughout the exercise trials, phlebodynamometric investigations were performed before and after each trial. Furthermore, subjective pain perception during and after exercise was accessed by visual analogue scale. One-way ANOVA was used to assess mean differences between training protocols, while two-way repeated-measures ANOVA (rANOVA; time x condition) was performed to compare changes in measures over time among conditions. Data were given as means ± standard deviation (SD). Results: In comparison to the exercise trials without venous occlusion, total workload was significantly lower in the LL-BFR-RT (LL-RT: 1745 ± 604kg vs LL-BFR-RT: 1274 ± 237kg vs HL-RT: 1847 ± 367kg, p = 0.004) without indicating statistical differences in venous pressures during the exercise sets (interaction: p = 0.140) or pain perception (interaction: p = 0.574). Similarly, phlebodynamometric assessment of venous function (e.g. refill-time of the venous system pre-vs. post exercise trials-LL-RT: 29.7 ± 11.0s vs 25.5 ± 9.6s, LL-BFR-RT: 26.6 ± 13.0s vs 27.3 ± 13.8s, HL-RT: 25.9 ± 10.9s vs 23.1 ± 8.2s) revealed no time (p = 0.156), condition effect (p = 0.802) or their interactions (p = 0.382). Conclusion: The present study is the first one describing the acute effects of LL-BFR-RT to muscle failure on venous pressures and function in comparison to a LL- and HL-RT in the lower limbs. In contrast to the existing literature, LL-BFR-RT does not elevate the venous pressures during exercise higher than a comparative exercise without BFR and does not show any adverse effects on venous function after the exercise.

Assessment of venous pressure by compression sonography of the internal jugular vein during 3days of bed rest.

Compression sonography has been proposed as a method for non-invasive measurement of venous pressures during spaceflight, but initial reports of venous pressure measured by compression ultrasound conflict with prior reports of invasively measured central venous pressure (CVP). The aim of this study is to determine the agreement of compression sonography of the internal jugular vein (IJVP) with invasive measures of CVP over a range of pressures relevant to microgravity exposure. Ten healthy volunteers (18-55years, five female) completed two 3-day sessions of supine bed rest to simulate microgravity. IJVP and CVP were measured in the seated position, and in the supine position throughout 3days of bed rest. The range of CVP recorded was in line with previous reports of CVP during changes in posture on Earth and in microgravity. The correlation between IJVP and CVP was poor when measured during spontaneous breathing (r=0.29; R2 =0.09; P=0.0002; standard error of the estimate (SEE)=3.0mmHg) or end-expiration CVP (CVPEE ; r=0.19; R2 =0.04; P=0.121; SEE=3.0mmHg). There was a modest correlation between the change in CVP and the change in IJVP for both spontaneous ΔCVP (r=0.49; R2 =0.24; P<0.0001) and ΔCVPEE (r=0.58; R2 =0.34; P<0.0001). Bland-Altman analysis of IJVP revealed a large positive bias compared to spontaneous breathing CVP (3.6mmHg; SD=4.0; CV=85%; P<0.0001) and CVPEE (3.6mmHg; SD=4.2; CV=84%; P<0.0001). Assessment of absolute IJVP via compression sonography correlated poorly with direct measurements of CVP by invasive catheterization over a range of venous pressures that are physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time. NEW FINDINGS: What is the central question of this study? Compression sonography has been proposed as a novel method for non-invasive measurement of venous pressures during spaceflight. However, the accuracy has not yet been confirmed in the range of CVP experienced by astronauts during spaceflight. What is the main finding and its importance? Our data show that compression sonography of the internal jugular vein correlates poorly with direct measurement of central venous pressures in a range that is physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time.

Supporting evidence for an "arterial pump" venous return mechanism in humans.

Blood flow in large veins is dependent on arterial-atrial pressure gradients and pumping mechanisms in concert with valve recruitment. Classic descriptions of muscle and respiratory pumps describe venous transmural pressure changes that cause flow. Not often considered is the transmission of pulsatile energy from arteries to veins directly adjacent to each other. Recently, an ex vivo study demonstrated a novel arterial pump effect in venoarterial bundles when valves were active in managing venous flow. We sought to show in vivo evidence of this arterial pump mechanism in 16 healthy young adults. Venous blood flow was measured in the venoarterial bundled deep femoral vein (DFV) and the greater saphenous vein (GSV), which is not bundled with an artery. Veins were studied through randomized body positions of -6° head-down tilt (HDT), supine, 20° head-up tilt (HUT), and 40° HUT, with the assumption that greater HUT postures increased valve dependence to observe the arterial pump effect. Between 20° and 40° HUT conditions, bundled DFV blood flow did not change (68 ± 36 vs. 71 ± 56 mL·min-1; Padj > 0.99), whereas nonbundled GSV blood flow decreased (6.1 ± 4.8 vs. 3.5 ± 3.9 mL·min-1; P = 0.01). Diameters between 20° and 40° HUT conditions increased in DFV (0.90 ± 0.16 vs. 1.04 ± 0.19 cm; P < 0.01), but not in GSV (0.33 ± 0.10 vs. 0.32 ± 0.08 cm; P = 0.60). These data support previous ex vivo observations that when venous pressure gradients rely on valve recruitment, presence of an adjacent artery may protect against further decreases in blood flow. The arterial pump mechanism is an underappreciated contributor to venous return and warrants further investigation.NEW & NOTEWORTHY Venous return mechanisms have classically considered muscle and respiratory pumps; however, recent ex vivo evidence suggests that pulsatile energy imparted from arteries to adjacent bundled veins can increase venous flow under certain driving pressures. We tested this concept in humans by manipulating hydrostatic pressures and measuring flow in bundled and nonbundled veins. The bundled vein exhibited flow preservation at the highest hydrostatic pressure. We suggest a novel conservation of energy mechanism within the circulatory system.

Predictive value of liver and spleen stiffness measurement based on two-dimensional shear wave elastography for the portal vein pressure in patients with compensatory viral cirrhosis.

This study aimed to explore the predictive value of liver and spleen stiffness measurement based on two-dimensional shear wave elastography for the portal vein pressure in patients with compensatory viral cirrhosis. From January 2017 to August 2019, 107 patients with compensatory viral cirrhosis and 76 patients with viral hepatitis were enrolled as cirrhosis group and hepatitis group, respectively. Patient data were obtained during admission, and this study was a review and analysis of patient data. Liver stiffness measurement (LSM), spleen stiffness measurement (SSM), portal vein diameter and spleen thickness were compared between the two groups, and their diagnostic value for compensatory viral cirrhosis was analyzed. According to the hepatic vein pressure, the cirrhosis group patients were divided into non-hypertensive group (no portal hypertension, hepatic venous pressure gradient (HVPG) < 5 mmHg), mild group (mild portal hypertension, 5 mmHg ≤ HVPG ≤ 10 mmHg) and severe group (clinically significant portal hypertension group, HVPG > 10 mmHg). LSM, SSM, portal vein diameter and spleen thickness of the three groups were compared, and the correlation between SSM and hepatic vein pressure was analyzed. LSM, SSM, portal vein diameter and spleen thickness in the cirrhosis group were higher than those in hepatitis group (all P<0.05). The area under the curve (AUC) of combined detection was larger than that of LSM, SSM and spleen thickness detection alone in liver cirrhosis diagnosis (all P<0.05). LSM, SSM, portal vein diameter and spleen thickness increased with the increase of hepatic vein pressure in patients with liver cirrhosis (all P<0.05). LSM, SSM, portal vein diameter and spleen thickness were all positively correlated with hepatic vein pressure (P<0.05). ROC curve showed that AUC of combined detection was greater than that of LSM, SSM, portal vein diameter and spleen thickness alone detection in the diagnosis of clinically significant portal hypertension (all P<0.05). The increase of LSM, SSM, portal vein diameter and spleen thickness were the influencing factors for hepatic vein pressure rising (all P<0.05). There was an increase of LSM and SSM in patients with compensatory viral cirrhosis, which were positively correlated with hepatic venous pressure, and combined index detection has diagnostic and predictive value for the change of portal venous pressure.

Real-world safety and effectiveness of inhaled nitric oxide therapy for pulmonary hypertension during the perioperative period of cardiac surgery: a post-marketing study of 2817 patients in Japan

ObjectiveTo evaluate the real-world safety and effectiveness of inhaled nitric oxide (INOflo® for Inhalation 800 ppm) for perioperative pulmonary hypertension associated with cardiac surgery in Japan.MethodsThis was a prospective, non-interventional, all-case, post-marketing study of pediatric and adult patients who received perioperative INOflo with cardiac surgery from November 2015–December 2020. Safety and effectiveness were monitored from INOflo initiation to 48 h after treatment completion or withdrawal. Safety outcomes included adverse drug reactions, blood methemoglobin concentrations, and inspired nitrogen dioxide concentrations over time. Effectiveness outcomes included changes in central venous pressure among pediatrics, mean pulmonary arterial pressure among adults, and the partial pressure of arterial oxygen/fraction of inspired oxygen ratio (PaO2/FiO2) in both populations.ResultsThe safety analysis population included 2,817 Japanese patients registered from 253 clinical sites (pediatrics, n = 1375; adults, n = 1442). INOflo was generally well tolerated; 15 and 20 adverse drug reactions were reported in 14 pediatrics (1.0%) and 18 adults (1.2%), respectively. No clinically significant elevations in blood methemoglobin and inspired nitrogen dioxide concentrations were observed. INOflo treatment was associated with significant reductions in both central venous pressure among pediatrics and mean pulmonary arterial pressure among adults, and significant improvements in PaO2/FiO2 among pediatrics and adults with PaO2/FiO2 ≤ 200 at baseline.ConclusionsPerioperative INOflo treatment was a safe and effective strategy to improve hemodynamics and oxygenation in patients with pulmonary hypertension during cardiac surgery. These data support the use of INOflo for this indication in Japanese clinical practice.

Location and extent of cavernous transformation of the portal vein dictates different visceral side revascularization in Meso-Rex bypass

BackgroundAs an emerging standard of care for portal vein cavernous transformation (PVCT), Meso-Rex bypass (MRB) has been complicated and variated. The study aim was to propose a new classification of PVCT to guide MRB operations.MethodsDemographic data, the extent of extrahepatic PVCT, surgical methods for visceral side revascularization, intraoperative blood loss, operating time, changes in visceral venous pressure before and after MRB, postoperative complications and the condition of bypass vessels after MRB were extracted retrospectively from the medical records of 19 patients.ResultsThe median age of the patients (13 males and 6 females) was 32.5 years, while two patients were underage. Causes of PVCT can be summarized as follows: thrombophilia such as dysfunction of antithrombin III or proteins C; secondary to abdominal surgeries; secondary to abdominal infection or traumatic intestinal obstruction, and unknown causes. Intraoperatively, the median operation time was 9.5 h (7–13 h), and the intraoperative blood loss was 300 mL (100-1,600 mL). Ten cases used autologous blood vessels while 10 used allogeneic blood vessels. The vascular anastomosis was divided into the following types according to the site and approach: Type (T) 1-PV pedicel type, T2-confluence type, T3-major visceral vascular type; and T4-collateral visceral vascular type. Furthermore, the visceral venous pressure before and after MRB dropped significantly from 36 cmH2O (28–44) to 24.5 cmH2O (15–31) (P < 0.01). Postoperatively, one patient had delayed wound healing, two developed biochemical pancreatic fistulae, one experienced lymphatic leakage, the former caused by heat damage of the pancreatic tissues, the latter by cutting lymphatic vessels in the mesentery or removing the local lymph nodes during the process of separating the superior mesenteric vein, and one was re-operated on for an intervening intestinal fistulae. Postoperative enhanced CT scans revealed a significant improvement in abdominal varix in the patients with patent bypass, and at the 1-year postoperative follow-up, enhanced CT scans of six patients showed that the long axis of the spleen was reduced by ≥ 2 cm.ConclusionsMRB can effectively reduce visceral venous pressure in patients with PVCT. It is feasible to determine the PVCT type according to the extent of involvement and to choose individualized visceral side revascularization performances.

Real-time quantification of bowel perfusion using Laparoscopic Laser Speckle Contrast Imaging (LSCI) in a porcine model

Background/purposeReal-time quantification of tissue perfusion can improve intraoperative surgical decision making. Here we demonstrate the utility of Laser Speckle Contrast Imaging as an intra-operative tool that quantifies real-time regional differences in intestinal perfusion and distinguishes ischemic changes resulting from arterial/venous obstruction.MethodsPorcine models (n = 3) consisted of selectively devascularized small bowel loops that were used to measure the perfusion responses under conditions of control/no vascular occlusion, arterial inflow occlusion, and venous outflow occlusion using laser speckle imaging and indocyanine green fluoroscopy. Laser Speckle was also used to assess perfusion differences between small bowel antimesenteric-antimesenteric and mesenteric-mesenteric anastomoses. Perfusion quantification was measured in relative perfusion units calculated from the laser speckle perfusion heatmap.ResultsLaser Speckle distinguished between visually identified perfused, watershed, and ischemic intestinal segments with both color heatmap and quantification (p < .00001). It detected a continuous gradient of relative intestinal perfusion as a function of distance from the stapled ischemic bowel edge. Strong positive linear correlation between relative perfusion units and changes in mean arterial pressure resulting from both arterial (R2 = .96/.79) and venous pressure changes (R2 = .86/.96) was observed. Furthermore, Laser Speckle showed that the antimesenteric anastomosis had a higher perfusion than mesenteric anastomosis (p < 0.01).ConclusionsLaser Speckle Contrast Imaging provides objective, quantifiable tissue perfusion information in both color heatmap and relative numerical units. Laser Speckle can detect spatial/temporal differences in perfusion between antimesenteric and mesenteric borders of a bowel segment and precisely detect perfusion changes induced by progressive arterial/venous occlusions in real-time.

Effect of Exogenous Albumin Replacement on Plasma Colloid Osmotic Pressure in Severe Preeclampsia: A Case-control Study

Background: In preeclampsia, hypoalbuminemia reduces plasma colloid osmotic pressure (PCOP) and favors capillary leakage. Replacement with exogenous albumin is a therapeutic alternative.&#x0D; Objective: to determine the effect of exogenous albumin replacement on PCOP in patients with severe preeclampsia (SP).&#x0D; Methods: A case-control study was carried out in 76 pregnant patients with SP from the Intensive Care Unit (ICU). The case group (n=38) received 0.9% saline solution 1000 ml every 8 hours and 25% albumin 50 ml every 8 hours and the control group (n=38) only received 0.9% saline solution 1000 ml every 8 hours. Plasma albumin concentrations, PCOP, hemodynamic and laboratory data from admission (baseline measurement) vs discharge from the ICU (final measurement) of both groups were compared.&#x0D; Statistical Analysis: the data was analyzed with descriptive statistics, paired Student's t-test and Pearson's correlation coefficient with the statistical program SPSS® version 20. The p value &lt;0.05 was significant.&#x0D; Results: A significant decrease in plasma albumin was found (case group 2.72±0.44 vs 2.45±0.48 g/dL, p=0.0141; control group 3.06±0.33 vs 2.58±0.29 g/dL, p=0.0431). PCOP was also significantly reduced (case group 18.44±2.92 vs 16.82±2.70 mmHg, p=0.0210; control group 20.38±2.28 vs 17.46±1.96 mmHg, p=0.0763). The group of cases showed an increase in uresis (p=0.0326), but without changes in central venous pressure (p=0.3246) and serum creatinine (p=0.9515). With this evidence the recommendation is that its use in patients with preeclampsia should be reserved for the experience of the medical team.&#x0D; Conclusion: Exogenous albumin replacement therapy did not correct the PCOP values or the blood albumin concentration.

Detection of Hemodialysis Venous Needle Dislodgment Using Venous Access Pressure Measurements: A Simulation Study.

In rare instances, hemodialysis venous needles may become dislodged, and when left undetected can lead to severe injury or death. Although dialysis machines have alarms to detect venous needle dislodgment, their range of detection is limited. An understanding of the clinical conditions that may lead to missed needle dislodgments is needed for development of more robust detection systems. We created a sham dialysis circuit with a Fresenius 2008 K dialysis machine for in vitro simulation testing of machine alarm behavior under variable conditions. The circuit used a blood substitute and mimicked a patient's venous access site. We varied blood flow rate, venous pressure, and upward drift in venous pressure and analyzed the time to alarm for the machine and an improved alarm algorithm. We also performed a cross-sectional retrospective study to identify the clinical occurrence of venous pressure upward drift between September 1, 2016, and November 1, 2016 in patients on hemodialysis with an arteriovenous fistula. Of 43,390 venous pressure readings for 147 patients on hemodialysis, 16,594 (38%) showed an upward drift in venous pressure (range 20-79 mmHg), with a mean ± SD increase of 11±18 mmHg within 20±14 minutes. A total of 19 venous needle dislodgment simulations under different venous pressure and blood flow parameters resulted in 19 (100%) algorithm alarm activations. Only 8 simulations (42%) activated a machine alarm, and machine alarm activation time was longer than the algorithm activation time for all 8 machine alarms (range 1-13 seconds). Patients can experience changes in venous pressure during hemodialysis which may not trigger a machine alarm in the case of a venous needle dislodgment. Our simulations showed that current dialysis machine alarm systems may not compensate for upward drift in venous pressure, and improved algorithms for detecting needle dislodgment during hemodialysis are needed.

Historical view onto the contribution of phlebodynamometry to the knowledge of venous hemodynamics in the lower extremity

Contribution of phlebodynamometry to the knowledge of the venous hemodynamics in the lower extremity is assessed from the historical point of view. Höjensgard, Stürup, and Arnoldi yielded in the 50's and 60's of the last century substantial information concerning changes of venous pressure in superficial and deep veins of the lower extremity arising during calf pump activity. They confirmed the previous finding that the venous pressure in the quiet standing position corresponds to the column of blood extending from the point of measurement to the heart. During calf pump activity, the systolic-diastolic amplitudes in lower leg veins are very marked; in contrast to that, they are only modest in the popliteal vein. The mentioned authors documented marked decrease in pressure in the posterior tibial vein as well as in the great saphenous vein arising during calf pump activity in healthy people. Contrary to that, the pressure in the popliteal vein did not decrease; it kept principally the value of the resting hydrostatic pressure. This difference of pressure between the thigh veins and the lower leg veins has been called ambulatory pressure gradient; its value in the examined patient cohort was 37.4±6.4 mm Hg. Ambulatory pressure gradient constitutes the suction force that triggers reflux in incompetent superficial and deep veins; this refluxing flow causes ambulatory venous hypertension. Simultaneous pressure recordings in the posterior tibial vein and great saphenous vein in healthy volunteers documented that the systolic and diastolic pressure amplitudes were similar in both veins. The systolic pressure in the posterior tibial vein increased on average by 75 mm Hg; this generates a strong impulse propelling the venous blood mainly into the popliteal vein, and partially into the great saphenous vein. Thus, there is a double-barreled outflow of venous blood from the lower extremity toward the heart. The steep increase in systolic pressure in the great saphenous vein gave evidence of the incompetence of the calf perforators system in healthy people. At present, plethysmography is able to yield similar information on the hemodynamic status of the lower limbs like phlebodynamometry.

Evaluation of Normal Inferior Vena Cava Diameters in the Indian Adult Population by Computed Tomography.

Background The imaging evaluation of inferior vena cava (IVC) diameters is essential for the estimation of vena caval pathologies and can also detect early hypovolemic shock.There are very few studies on normal IVCdiameters on CT scan done in foreign countries, and none done in the Indian population. Aims The goal of this research is to assess the normal IVCdiameter in the Indian adult population by performing a CT scan of the abdomen. Material and methods In this study, CT scans of 200 individuals (aged 19-83) without any circulatory and vascular disorders were analyzed retrospectively. The anteroposterior (AP) and transverse diameters of the IVCwere measured at the level of the renal vein and at the level 2 cm proximal to insertion in the heart (usual area of measurement on ultrasonography). Results The study discovered normal adult mean AP and transverse dimensions of the IVCat the level of the renal vein as 16.3 ± 2.9 mm and 25.8 ± 3.5 mm, respectively, and 16.9 + 3.2 mm and 26.2 + 3.6 mm at the level 2 cm proximal to its insertion in the right atrium. Conclusions In this study, the normal morphometric dimensions of the IVCin the Indian adult population were established. The diameters of the IVC and the age of the participants in our study had no statistically significant correlation, however, the IVCchanges its cross-sectional area and diameter due to changes in venous pressure and blood pressure and hence is a highly compliant vessel. The results of the study will be used as baseline data for the assessment of IVCdisorders.

The Impact Of Varying Blood Flow Restriction Cuff Size On Cardiac Autonomic Modulation In Healthy Males

Blood flow restriction (BFR) training is commonly utilized to stimulate skeletal muscle hypertrophy and assist in strength gains in various populations, ranging from healthy, athletic, clinical, and elderly populations. BFR has the potential to influence the sympathetic and parasympathetic interaction by stimulating acute changes in the vascular endothelium, thereby altering cardiac autonomic modulation (CAM). Heart rate variability (HRV) is a non-invasive way to assess changes in CAM. What is unknown is the influence BFR may have on CAM due to the changes in venous and arterial pressure. PURPOSE: To determine if different BFR cuff sizes and materials alter CAM when assessed in healthy young men. METHODS: Twenty healthy males (n = 20 males, Age 25 ± 5 years, HR 66 + 11.3 bpm, SBP 125.1 + 13.4 mmHg, DBP 75.1 + 12.5 mmHg) completed a randomized, counter-balanced, cross-over design that utilized a widely-employed wide rigid (WR) cuff, along with the largest (NE) and manufacturer recommended sizes (NER) of a novel narrow-elastic cuff. HRV was measured in the supine position at baseline and amidst all three BFR cuffs at 80% arterial occlusion pressure using an elastic belt and Bluetooth monitor (Polar H7). CardioMood software was used to process HRV variables high frequency (HF), low frequency (LF), total power (TP) was assessed for frequency domain, and standard deviation of all NN intervals (SDNN) and the square root of the mean of the squares of successive R-R interval differences (RMSSD) for the time domain. The data were analyzed with SPSS using a repeated-measures ANOVA to examine differences between dependent variables, including selected time and frequency domain HRV indices. RESULTS: HRV frequency domain variables LF, HF, LF/HF, and TP, and time domain, SDNN, and RMSSD variables were not significantly altered with WR, NE, or NER cuff protocols when compared to baseline. There were no significant differences between cuff protocols. CONCLUSION: There were no changes in CAM with BFR cuff protocols in healthy young men. The lack of changes indicates that changes in the venous and arterial pressure ratio due to BFR were not great enough to offset the sympathetic and parasympathetic systems.

Bedside ultrasound to assess acute central venous pressure change during treatment of decompensated heart failure.

Accurate volume status assessment is crucial for the treatment of acute decompensated heart failure (ADHF). Volume status assessment by physical exam is often inaccurate, necessitating invasive measurement with right heart catheterization (RHC), which carries safety, pragmatic (scheduling, holding anticoagulants, etc.), and financial burdens. Therefore, a reliable, non-invasive, cost-effective alternative is desired. Previously, we developed an ultrasound (US) based technique to measure internal jugular vein (IJV) compliance during RHC which was used for single time point central venous pressure (CVP) predictions. We now aim to apply this technique to track acute changes in CVP during diuresis for ADHF in patients with an in-dwelling pulmonary artery catheter (PAC). We used an observational, prospective study design and recruited 15 patients from the cardiac critical unit (CCU) being treated for ADHF (systolic or diastolic) with intravenous (IV) diuretics with/without inotropic agents who underwent Swan- Ganz catheter/PAC insertion for continuous CVP monitoring. 13 of 15 patients received milrinone infusions. US images of the IJV were obtained at end-expiration and during the strain phase of Valsalva at multiple 2-3 hours intervals. Change in IJV cross-sectional area (CSA) (ImageJ) was used as a measure of IJV compliance. Patients unable to perform the Valsalva maneuver were excluded. Calculated percentage change (%Δ) in CSA of IJV was plotted against CVP. An inverse relationship was observed between CVP and %Δ in CSA of IJV. The data was fit with a polynomial regression curve (R2=0.36, root mean square error=3.19). Fivefold cross-validation showed a stable model for predicting CVP based on CSA (R2=0.31, root mean square error=3.18). Serial portable US assessment of IJV compliance can act as a surrogate measure of CVP and, therefore, can provide reliable information on acute hemodynamic changes in ADHF.