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Precise fluid therapy is extremely important during surgeries, as enough circulating blood volume ensures tissue perfusion and cell oxygenation. Yet, extra fluid volume could cause other adverse events, such as heart failure, intestinal swelling, etc. Thus, precise evaluation of the circulating blood volume is essential for maintaining sufficient circulating blood volume and avoiding excessive fluid infusion. This study aimed to evaluate the relationship between SVV and circulating blood volume during intraoperative fluid therapy. SVV was measured by FloTrac/Vigileo in the study. A prospective cohort study was conducted. 103 patients aged from 20 to 60 years old with an ASA Grade I-II and a diagnosis of meningioma less than 3 centimeters planning for selective neurosurgery were randomly divided into the Crystalloid Group and the Colloid Group. After induction, each Patient received 15 ml/kg of Plasma-Lyte-A or 6% hydroxyethyl starch in 30 min followed by continuous infusion at the speed of 0.1 ml/kg during the next 60 min. Hb concentration, Hct, Delta-BV/kg, and Delta-SVV were recorded every 5 minutes. The delta-SVV and Delta-bv/kg were significantly higher in the Crystalloid Group than that of the Colloid Group. There was a strong linear correlation between Delta-SVV and Delta-bv/kg in both Crystalloid Group (Delta-bv / kg = 1.108 Delta-SVV + 0.0712, P < .001) and Colloid Group (Delta-bv / kg = 1.047 Delta-SVV + 0.4153, P < .001). An equation between Delta-bv/kg and Delta-SVV was established (Delta-bv / kg = 1.099 Delta-SVV + 0.1139, P < .001). In conclusion, SVV measured by FloTrac / Vigileo could guile fluid therapy precisely by predicting the blood volume of patients during the intraoperative period, as it has a strong linear correlation with the blood volume of patients who underwent general anesthesia, meaning anesthesiologist could calculate the exact fluid volume for patients' infusion. Further studies with large cohorts and centers would be needed to validate its efficiency.

Accurate assessment of volume status is critical in the management of patients with heart failure (HF). We studied the utility of a pocket-sized ultrasound device in an outpatient cardiology clinic as a tool to guide volume assessment. Inferior vena cava (IVC) size and collapsibility were assessed in 95 patients by residents briefly trained in focused cardiac ultrasound (FCU). Cardiologist assessment of volume status and changes in diuretic medication were also recorded. Patients were followed for occurrence of 30-day events. There was a 94% success rate of obtaining IVC size and collapsibility, and agreement between visual and calculated IVC parameters was excellent. Most patients were euvolemic by both FCU IVC and clinical bedside assessment (51%) and had no change in diuretic dose. Thirty-two percent had discrepant FCU IVC and clinical volume assessments. In clinically hypervolemic patients, the FCU evaluation of the IVC suggested that the wrong diuretic management plan might have been made 46% of the time. At 30 days, 14 events occurred. The incidence of events increased significantly with FCU IVC imaging categorization, from 11% to 23% to 36% in patients with normal, intermediate, and plethoric IVCs. By comparison, when grouped in a binary manner, there was no significant difference in event rates for patients who were deemed to be clinically volume overloaded. Assessment of volume status in an outpatient cardiology clinic using FCU imaging of the IVC is feasible in a high percentage of patients. A group of patients were identified with volume status discordant between FCU IVC and routine clinic assessment, suggesting that IVC parameters may provide a valuable supplement to the in-office physical examination.

Magnetic Particle Imaging (MPI) is a rapidly developing imaging modality that directly measures and maps the concentration of injected superparamagnetic iron oxide nanoparticles (SPIOs). Since the agent does not cross the blood-brain barrier, cerebral SPIO concentration provides a direct probe of Cerebral Blood Volume (CBV). Here we provide an initial demonstration of the ability of MPI to detect functional CBV changes (fCBV) by monitoring SPIO concentration during hypercapnic manipulation in a rat model. As a tracer detection method, MPI offers a more direct probe of agent concentration and therefore fCBV than MRI measurements in which the agent is indirectly detected through perturbation of water relaxation time constants such as T2∗. We found that MPI detection could measure CBV changes during hypercapnia with high CNR (CNR = 50) and potentially with high temporal resolution. Although the detection process more closely resembles a tracer method, we also identify evidence of physiological noise in the MPI time-series, with higher time-series variance at higher concentration levels. Our findings suggest that CBV-based MPI can provide a detection modality for hemodynamic changes. Further investigation with tomographic imaging is needed to assess tomographic ability of the method and further study the presence of time-series fluctuations which scale with signal level similar to physiological noise in resting fMRI time-courses. •A single-sided Magnetic Particle (MP) detector was developed for rodent CBV measurements.•Phantom experiments validated sensitivity to physiologically relevant SPIO concentrations.•fCBV measurements during hyper/hypocapnia detected CBV modulations with CNR = 50.•Observed physiological noise in the resting-state merits further study.

The prognostic implications of intravascular volume status assessed by blood volume analysis (BVA) in ambulatory heart failure (HF) remain uncertain. The incremental benefits of assessing volume status, beyond the well-established filling pressures, in predicting HF outcomes are unknown.

HAEMOMASTER system developed by NIKKISO is a feedback control technology that combines blood volume monitoring, which is now increasingly used in many dialysis centers. We investigated the effectiveness and safety of five slopes provided by HAEMOMASTER system. Patients undergoing hemodialysis with the support of a blood volume monitor (BVM) were enrolled. The NIKKISO DBB-05 Hemodialysis machine had automatically recorded real-time data such as BV and BP. Data from the patients' previous 10 dialysis sessions were collected into the HAEMOMASTER system for data fitting and the calculated target ΔBV. Patients received dialysis treatment with five slopes of the HEAMOMASTER system. We record the actual ΔBV and reverse events of every slope. Relative index to ΔBV of different slopes and sub-analysis was conducted by two-variable Spearman correlation analysis. One hundred participants entered, and 78 completed the study. Slope1 and Slope2 had a lower incidence of adverse reactions (5.3% and 3.8%) and higher correlation coefficients (0.827 and 0.831, P < .001), which means they can reflect dialysis physiology better. HEAMOMASTER system helps the hemodialysis physician develop an optimal individual hemodialysis plan for the patient, reduce adverse effects such as hypotension ,obvious sweating, palpitation, fatigue, and the hemodialysis process is interrupted or the ultrafiltration volume being adjusted. We evaluated the safety and effectiveness of the HAEMOMASTER System in hemodialysis patients. This study serves as a roadmap for the development and widespread use of the HAEMOMASTER system and a resource for the creation of novel biofeedback control strategies. The HAEMOMASTER system has good clinical application prospects in hemodialysis patients and can be used to develop individualized ultrafiltration schemes for patients and improve the comfort and safety of hemodialysis. Slope1 and Slope2 of HAEMOMASTER are more suitable for the majority of patients with a better fit to the actual physiological conditions and lower incidence of adverse events.

Photoplethysmography (PPG) is a non-invasive photometric technique that measures the volume changes in arterial blood. Recent studies have reported limitations in developing and optimising PPG-based sensing technologies due to unavailability of the fundamental information such as PPG-pathlength and penetration depth in a certain region of interest (ROI) in the human body. In this paper, a robust computational model of a dual wavelength PPG system was developed using Monte Carlo technique. A three-dimensional heterogeneous volume of a specific ROI (i.e., human finger) was exposed at the red (660 nm) and infrared (940 nm) wavelengths in the reflectance and transmittance modalities of PPG. The optical interactions with the individual pulsatile and non-pulsatile tissue-components were demonstrated and the optical parameters (e.g., pathlength, penetration depth, absorbance, reflectance and transmittance) were investigated. Results optimised the source-detector separation for a reflectance finger-PPG sensor. The analysis with the recorded absorbance, reflectance and transmittance confirmed the maximum and minimum impact of the dermis and bone tissue-layers, respectively, in the formation of a PPG signal. The results presented in the paper provide the necessary information to develop PPG-based transcutaneous sensors and to understand the origin of the ac and dc components of the PPG signal.

Background (1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of this technique in patients who were treated for an intracranial aneurysm. Methods Four repeated measurements of blood volume (BV) were performed in random order of bolus dose (10 mg or 25 mg ICG) and venous administration site (peripheral or central) in eight patients admitted for treatment of an intracranial aneurysm. Another five patients with subarachnoid hemorrhage underwent three repeated BV measurements with 25 mg ICG at the same administration site to assess the coefficient of variation. Findings The mean ± SD in BV was 4.38 ± 0.88 l (n = 25) and 4.69 ± 1.11 l (n = 26) for 10 mg and 25 mg ICG, respectively. The mean ± SD in BV was 4.59 ± 1.15 l (n = 26) and 4.48 ± 0.86 l (n = 25) for central and peripheral administration, respectively. No significant difference was found. The coefficient of variance of BV measurement with 25 mg of ICG was 7.5% (95% CI: 3–12%). Conclusions There is no significant difference between intravenous administration of either 10 or 25 mg ICG, and this can be injected through either a peripheral or central venous catheter. The 7.5% coefficient of variation in BV measurements determines the detectable differences using ICG pulse spectrophotometry.

An element lacking in medical education is training to estimate blood volumes. Therefore, health care workers currently use visual estimation as their only means of determining blood volumes, which has shown to be highly inaccurate. This study proposes and tests a new method using one's fist to determine external blood loss. Increments of human whole blood were measured and used to compare fist size to surface area of blood present. A formula was created averaging blood per fist, hereafter known as the MAR Method. Two scenarios were staged using set quantities of blood (75 and 750 mL). Participants estimated blood volumes before and after being taught the MAR Method in a 1-minute session. Errors in estimation before and after using the MAR Method were compared. The MAR Method was created using a fist to cover a surface area of blood that equals 20 mL. A total of 74 participants had errors of 120% and 73% for visualization of the small and large pools, respectively. For the smaller volume, the average error from the mean decreased by 76% ( P < .0001), and the interquartile range of errors decreased by 60%. For the larger volume, the average error from the mean reduced by 40% ( P < .0001), and the interquartile range of errors reduced by 45%. Use of the MAR Method improves blood volume estimations. After less than 1 minute of instruction, participants were able to determine blood volumes with improved accuracy and precision.

PurposeCerebral blood volume (CBV) maps created using dynamic susceptibility contrast-enhanced perfusion weighted imaging (DSC-PWI) are valuable but may be limited by gadolinium contraindications in certain clinical scenarios. A noninvasive perfusion method for CBV assessment based on velocity-selective (VS) ASL has emerged. This study is to evaluate the performance of VSASL-derived CBV among glioma patients in clinical practice, comparing with the VSASL-based cerebral blood flow (CBF) and DSC-PWI.MethodsForty-eight patients with pathologically confirmed gliomas (mean age: 45 ± 13 years; 25 males; 25 in low-grade) underwent preoperative VSASL-CBV MRI. Lesion conspicuity on VSASL-CBV maps was visually scored (1–3) relative to surrounding parenchyma by two neuroradiologists. Relative maximum tumor blood volume (rTBV) and flow (rTBF) from VSASL and DSC-PWI were compared between low- and high-grade gliomas. Correlation and agreement between VSASL- and DSC-PWI-derived rTBV were assessed via linear regression and Bland–Altman analysis. Diagnostic performance for glioma grading was evaluated using ROC curves.ResultsVSASL-CBV maps demonstrated good lesion conspicuity (mean score: 2.26 ± 0.76; inter-reader weighted κ = 0.8). VSASL-rTBV strongly correlated with DSC-PWI-rTBV (R²=0.83, p < 0.001). Both VSASL and DSC-PWI metrics significantly distinguished low- from high-grade gliomas (p < 0.001). ROC analysis revealed that VSASL-rTBV achieved excellent diagnostic accuracy in glioma grading (AUC = 0.94), outperforming VSASL-rTBF (AUC = 0.89) and matching DSC-PWI-rTBV (AUC = 0.93). Sensitivity, predictive values, and accuracy of VSASL-rTBV were superior to VSASL-rTBF.ConclusionVSASL provides accurate, noninvasive CBV quantification for glioma stratification, demonstrating diagnostic performance comparable to DSC-PWI. It offers a viable alternative in clinical settings where gadolinium contrast is contraindicated.

Monitoring of continuous blood pressure and cardiac output is important to prevent hypoperfusion and to guide fluid administration, but only few patients receive such monitoring due to the invasive nature of most of the methods presently available. Noninvasive blood pressure can be determined continuously using finger cuff technology and cardiac output is easily obtained using a pulse contour method. In this way completely noninvasive continuous blood pressure and cardiac output are available for clinical use in all patients that would otherwise not be monitored. Developments and state of art in hemodynamic monitoring are reviewed here, with a focus on noninvasive continuous hemodynamic monitoring form the finger.