Automated blood volume estimation in surgical drains for clinical decision support.

OBJECTIVE: Monitoring Jackson Pratt and Hemovac drains plays a crucial role in assessing a patient's recovery and identifying potential postoperative complications. Accurate and regular monitoring of the blood volume in the drain is essential for making decisions about patient care. However, transferring blood to a measuring cup and recording it is a challenging task for both patients and doctors, exposing them to bloodborne pathogens such as the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). To automate the recording process with a non-contact approach, we propose an innovative approach that utilizes deep learning techniques to detect a drain in a photograph, compute the blood level in the drain, estimate the blood volume, and display the results on both web and mobile interfaces. MATERIALS AND METHODS: Our system employs semantic segmentation on images taken with mobile phones to effectively isolate the blood-filled portion of the drain from the rest of the image and compute the blood volume. These results are then sent to mobile and web applications for convenient access. To validate the accuracy and effectiveness of our system, we collected the Drain Dataset, which consists of 1,004 images taken under various background and lighting conditions. RESULTS: With an average error rate of less than 5% in milliliters, our proposed approach achieves highly accurate blood level detection and estimation, as demonstrated by our trials on this dataset. The system also exhibits robustness to variations in lighting conditions and drain shapes, ensuring its applicability in different clinical scenarios. CONCLUSIONS: The proposed automated blood volume estimation system can significantly reduce the time and effort required for manual measurements, enabling healthcare professionals to focus on other critical tasks. The dataset and annotations are available at: https://www.kaggle.com/datasets/ayenahin/liquid-volume-detection-from-drain-images and the code for the web application is available at https://github.com/itsjustaplant/AwesomeProject.git.

Prognostic implications of volume status assessed by blood volume analysis in ambulatory heart failure.

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.

Comparison of blood volume biofeedback hemodialysis and conventional hemodialysis on cardiovascular stability and blood pressure control in hemodialysis patients: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Despite the improvements in hemodialysis (HD) technology, 20-30% of sessions are still complicated by hypotension or hypotension-related symptoms. Biofeedback systems have proven to reduce the occurrence of such events, but no conclusive findings can lead to wider adoption of these systems. We conducted this systematic review and meta-analysis of randomized clinical trials to establish whether the use of blood volume tracking systems compared to conventional hemodialysis (C-HD) reduces the occurrence of intradialytic hypotension. METHODS: The PRISMA guidelines were used to carry out this systematic review. Randomized clinical trials that evaluated the incidence of intradialytic hypotension during C-HD and blood volume tracking-HD were searched in the current literature. PROSPERO registration number: CRD42023426328. RESULTS: Ninety-seven randomized clinical trials were retrieved. Nine studies, including 347 participants and 13,274 HD treatments were considered eligible for this systematic review. The results showed that the use of biofeedback systems reduces the risk of intradialytic hypotension (log odds ratio = 0.63, p = 0.03) in hypotension-prone patients (log odds ratio = 0.54, p = 0.04). When analysis was limited to fluid overloaded or hypertensive patients, it did not show the same effect (log odds ratio = 0.79, p = 0.38). No correlation was found in systolic blood pressure drop during dialysis and in post-dialysis blood pressure. CONCLUSIONS: The use of blood volume tracking systems may be effective in reducing the incidence of intradialytic hypotension and allowing for easier attainment of the patients' ideal dry body weight. New studies to examine the long-term effects of the use of blood volume tracking systems on real hard endpoints are needed.

Haematocrit monitoring and blood volume estimation during continuous renal replacement therapy.

BACKGROUND: Continuous haemoglobin, venous blood oxygen saturation, and haematocrit (Hct) monitoring is currently not applied during continuous renal replacement therapy (CRRT). Such Hct monitoring enables estimation of changes in blood volume as percentage change (ΔBV%) from therapy start time and is incorporated into intermittent haemodialysis machines but not CRRT machines despite its potential to optimise fluid management in CRRT patients. METHODS: To overcome this problem, we used a standalone monitor (CRIT-LINE®IV, Fresenius Medical Care, Concord, USA) with an associated in-line blood chamber (CRIT-LINE®IV Blood Chamber, Fresenius Medical Care, Concord, USA) and designed our own adaptor connection piece (TekMed and Morriset, Melbourne and Brisbane, Australia) to allow these readings at the vascular access outflow and recorded data for estimated Hct and derived ΔBV% during CRRT. RESULTS: We report on this technique with an illustrative case example and 12 h of CRRT data on the fluid loss rate prescribed, hourly net patient fluid loss (range: 0-308 mL/h), mean arterial pressure, norepinephrine dose (range: 5-14 mcg/min), estimated continuous Hct and ΔBV%, and the otherwise undetected diagnosis of an approximate 15 % decrease in blood volume during the CRRT. CONCLUSION: We have described a technical CRRT circuit modification that can facilitate a previously unavailable assessment of fluid shifts during CRRT. Further application in clinical trials is now possible.

Residual volume fraction during walking using wireless air plethysmography in patients with chronic deep venous disease.

OBJECTIVE: Traditional air plethysmography (APG) provides a quantitative measure of the residual volume fraction (RVF) after 10 tiptoe movements. The recent development of a wireless Bluetooth (Bluetooth SIG, Inc, Kirkland, Wash) APG device, the PicoFlow (Microlab Elettronica, Padua, Italy), enabled us to measure RVF during normal walking. The aim of our study was to compare the RVF obtained during tiptoeing with RVF obtained during normal walking in patients with deep venous pathology (ie, reflux and/or obstruction). METHODS: A total of 61 consecutive symptomatic patients (27 women and 34 men; median age, 46 years; range, 18-79 years) with chronic venous disease due to deep venous pathology (venous reflux or obstruction, or both) before treatment or persisting after intervention were included in the present study. Of the 122 total limbs examined, 79 were affected by deep chronic venous disease and 43 contralateral limbs were normal with normal deep veins and acted as controls. The APG examination was performed using the PicoFlow device using the standard examination technique. The RVF was calculated from the residual volume at the end of 10 tiptoe movements and also during normal walking. RESULTS: At the end of the 10 tiptoe movements, the mean ± standard deviation RVF was 27.0% ± 13.2% in the limbs with normal deep veins and 38.8% ± 16.9% in the limbs with deep chronic venous disease (P < .001). During walking, when a steady state in volume was reached, the RVF was 26.3% ± 17.8% in the limbs with normal deep veins and 43.1% ± 18.6% in limbs with deep venous disease (P < 0.001). A significant difference was found between limbs with normal deep veins and limbs with deep venous reflux, irrespective of which exercise was performed. However, the mean RVF between the limbs with normal deep veins and those with outflow obstruction in the absence of reflux was significant during walking (P = .012) but not during tiptoeing (P = .212). The mean RVF was higher in the C3 to C6 limbs than in the C0 to C2 limbs with tiptoeing (29.9% ± 14.5% vs 38.3% ± 17.0%; P < .006). Similar results were obtained with walking (29.2% ± 18.0% vs 42.4% ± 18.8%; P < .004). CONCLUSIONS: In limbs with normal deep veins and deep veins with reflux, the RVF measured during walking with wireless APG was similar to the RVF obtained during tiptoeing. However, in the limbs with outflow obstruction in the absence of reflux, the RVF during walking was higher than the RVF after tiptoeing. Our results have shown that the evaluation of RVF during walking is feasible and practical.

Blood volume expansion, normovolemia, and clinical outcomes in chronic human heart failure: more is better.

Expansion in blood volume (BV) is a well-recognized response to arterial underfilling secondary to impaired cardiac output in heart failure (HF). However, the effectiveness of this response in terms of outcomes remains inadequately understood. Prospective analysis was undertaken in 110 patients with HF hospitalized and treated for fluid overload. BVs were measured in a compensated state at the hospital discharge using the indicator-dilution methodology. Data were analyzed for composite 1-year HF-related mortality/first rehospitalization. Despite uniform standard of care, marked heterogeneity in BVs was identified across the cohort. The cohort was stratified by BV expansion greater than or equal to +25% above normal (51% of cohort), mild-moderate expansion (22%), and normal BV (27%). Kaplan-Meier (K-M) survival estimates and regression analyses revealed BV expansion (greater than or equal to +25%) to be associated with better event-free survival relative to normal BV (P = 0.038). Increased red blood cell mass (RBCm; RBC polycythemia) was identified in 43% of the overall cohort and 70% in BV expansion greater than or equal to +25%. K-M analysis demonstrated polycythemia to be associated with better outcomes compared with normal RBCm (P < 0.002). Persistent BV expansion to include RBC polycythemia is common and, importantly, associated with better clinical outcomes compared with normal total BV or normal RBCm in patients with chronic HF. However, compensatory BV expansion is not a uniform physiological response to the insult of HF with marked variability in BV profiles despite uniform standard of care diuretic therapy. Therefore, recognizing the variability in volume regulation pathophysiology has implications not only for impact on clinical outcomes and risk stratification but also potential for informing individualized volume management strategies.NEW & NOTEWORTHY The novel findings of this study demonstrate that intravascular volume profiles among the patients with chronic heart failure (HF) vary substantially even with similar clinical compensation. Importantly, a profile of blood volume (BV) expansion (compared with a normal BV) is associated with lower HF mortality/morbidity. Furthermore, RBC polycythemia is common and independently associated with improved outcomes. These observations support BV expansion with RBC polycythemia as a compensatory mechanism in chronic HF.

Measuring the ratio of femoral vein diameter to femoral artery diameter by ultrasound to estimate volume status.

BACKGROUND: Currently, the accepted effective method for assessing blood volume status, such as measuring central venous pressure (CVP) and mean pulmonary artery pressure (mPAP), is invasive. The purpose of this study was to explore the feasibility and validity of the ratio of the femoral vein diameter (FVD) to the femoral artery diameter (FAD) for predicting CVP and mPAP and to calculate the cut-off value for the FVD/FAD ratio to help judge a patient's fluid volume status. METHODS: In this study, 130 patients were divided into two groups: in group A, the FVD, FAD, and CVP were measured, and in group B, the FVD, FAD, and mPAP were measured. We measured the FVD and FAD by ultrasound. We monitored CVP by a central venous catheter and mPAP by a Swan-Ganz floating catheter. Pearson correlation coefficients were calculated. The best cut-off value for the FVD/FAD ratio for predicting CVP and mPAP was obtained according to the receiver operating characteristic (ROC) curve. RESULTS: The FVD/FAD ratio was strongly correlated with CVP (R = 0.87, P < 0.0000) and mPAP (R = 0.73, P < 0.0000). According to the ROC curve, an FVD/FAD ratio ≥ 1.495 had the best test characteristics to predict a CVP ≥ 12 cmH2O, and an FVD/FAD ratio ≤ 1.467 had the best test characteristics to predict a CVP ≤ 10 cmH2O. An FVD/FAD ratio ≥ 2.03 had the best test characteristics to predict an mPAP ≥ 25 mmHg. According to the simple linear regression curve of the FVD/FAD ratio and CVP, when the predicted CVP ≤ 5 cmH2O, the FVD/FAD ratio was ≤ 0.854. CONCLUSION: In this study, the measurement of the FVD/FAD ratio obtained via ultrasound was strongly correlated with CVP and mPAP, providing a non-invasive method for quickly and reliably assessing blood volume status and providing good clinical support.

Relation of Intravascular Volume Profiles to Heart Failure Progression and Clinical Outcomes.

Heart failure (HF) commonly progresses over time and identifying differences in volume profiles may help stratify risk and guide therapy. The aim of this study was to assess the pathophysiologic and prognostic roles of volume profiles for HF progression in stable ambulatory and hospitalized patients. HF patients who had undergone quantitative intravascular volume analysis (185 outpatients and 139 inpatients) were retrospectively assessed for the combined end point of HF-related hospital admissions (outpatients), HF-readmissions (inpatients), and overall all-cause mortality. After multivariate Cox regression analysis, greater total blood volume expansion was associated with higher risk of HF-admission in previously stable outpatients (HR: 1.023, CI 1.005 to 1.043; p = 0.013) while in more advanced HF (inpatients) total blood volume expansion was associated with lower risk for HF-readmission and mortality (HR: 0.982, CI 0.967 to 0.997; p = 0.017). Secondary analysis suggests that subclinical plasma volume expansion was a driving factor for the detrimental association in outpatients (HR: 1.018, CI 0.997 to 1.036; p = 0.054), while an increase in red blood cell mass was central to the beneficial association in advanced HF (HR: 0.979, CI 0.968 to 0.991; p <0.001). In conclusion, understanding differences in plasma volume and red blood cell mass profiles can provide insight into the pathophysiology and progression of HF.

Effects of whole blood storage in a polyolefin blood bag on platelets for acute normovolemic hemodilution.

Acute normovolemic hemodilution (ANH) is a potential transfusion method for platelets, as well as for red blood cells. However, previous studies have shown that whole blood storage in ANH decreases platelet aggregability by 14.7-76.3% and that this decrease is not recovered by reinfusion. We investigated whether a new whole blood storage method for 6 h using a polyolefin bag, based on the platelet concentrates storage method, would maintain platelet function better than the conventional method using a polyvinyl chloride bag. We demonstrated that storage of whole blood in a polyolefin bag maintained ADP-induced aggregation rates at more than twofold higher than those in a polyvinyl chloride bag, and also significantly suppressed P-selectin expression, a platelet activation marker (ADP-induced aggregation rates: 24.6 ± 5.1% vs. 51.7 ± 11.5%, p = 0.002; P-selectin expression; 50.3 ± 8.4MFI vs. 31.6 ± 9.3MFI, p = 0.018). These results could be attributed to the high gas permeability of polyolefin, which lowered PCO2 and maintained a high pH with or without agitation. There were no significant changes in platelet count and red blood cell parameters due to the storage methods. Our results suggest that ANH using polyolefin bags is advantageous in improving hemostatic function compared to the conventional method.

The visually estimated blood volume in scaled canisters based on a simulation study.

BACKGROUND: The most common technique used worldwide to quantify blood loss during an operation is the visual assessment by the attending intervention team. In every operating room you will find scaled suction canisters that collect fluids from the surgical field. This scaling is commonly used by clinicians for visual assessment of intraoperative blood loss. While many studies have been conducted to quantify and improve the inaccuracy of the visual estimation method, research has focused on the estimation of blood volume in surgical drapes. The question whether and how scaling of canisters correlates with actual blood loss and how accurately clinicians estimate blood loss in scaled canisters has not been the focus of research to date. METHODS: A simulation study with four "bleeding" scenarios was conducted using expired whole blood donations. After diluting the blood donations with full electrolyte solution, the sample blood loss volume (SBL) was transferred into suction canisters. The study participants then had to estimate the blood loss in all four scenarios. The difference to the reference blood loss (RBL) per scenario was analyzed. RESULTS: Fifty-three anesthetists participated in the study. The median estimated blood loss was 500 ml (IQR 300/1150) compared to the RBL median of 281.5 ml (IQR 210.0/1022.0). Overestimations up to 1233 ml were detected. Underestimations were also observed in the range of 138 ml. The visual estimate for canisters correlated moderately with RBL (Spearman's rho: 0.818; p < 0.001). Results from univariate nonparametric confirmation statistics regarding visual estimation of canisters show that the deviation of the visual estimate of blood loss is significant (z = - 10.95, p < 0.001, n = 220). Participants' experience level had no significant influence on VEBL (p = 0.402). CONCLUSION: The discrepancies between the visual estimate of canisters and the actual blood loss are enormous despite the given scales. Therefore, we do not recommend estimating the blood loss visually in scaled suction canisters. Colorimetric blood loss estimation could be a more accurate option.

Association between splenic volume and pulsatility index in patients with left ventricular assist devices.

The spleen serves as a blood volume reservoir for systemic volume regulation in heart failure (HF) patients. Changes are seen in spleen size in advanced HF patients after left ventricular assist device (LVAD) implantation. The pulsatility index (PI) is an indicator of native heart contractility with hemodynamic changes in patients using LVAD. We hypothesized that the splenic volume was associated with the PI, reflecting the hemodynamics in advanced HF patients with LVADs. Herein, we investigated the relationship between splenic volume and PI in these patients. Forty-four patients with advanced HF underwent implantation of HeartMate II® (Abbott, Chicago, IL, USA) as a bridge to heart transplantation at the Nagoya University Hospital between October 2013 and June 2019. The data of 27 patients (21 men, median age 46 years) were analyzed retrospectively. All patients underwent blood tests, echocardiography, right heart catheterization, and computed tomography (CT). Spleen size was measured via CT volumetry; the splenic volume (median: 190 mL) correlated with right arterial pressure (r = 0.431, p = 0.025) and pulmonary capillary wedge pressure (r = 0.384, p = 0.048). On multivariate linear regression analysis, the heart rate (ß = -0.452, p = 0.003), pump power (ß = -0.325, p = 0.023), and splenic volume (ß = 0.299, p = 0.038) were independent determinants of PI. The splenic volume was associated with PI, reflecting the cardiac preload in advanced HF patients with LVADs. Thus, spleen measurement using CT may help estimate the systemic volume status and understand the hemodynamic conditions in LVAD patients.

The Nephrologist as an Ultrasonographer.

Ultrasonography is increasingly being used in the practice of nephrology, whether it is for diagnosis or management of acute or chronic kidney dysfunction, until progression to end-stage kidney disease, including preoperative assessment, access placement, and diagnosis and management of dysfunctional hemodialysis access. Point-of-care ultrasounds are also being used by nephrologists to help manage volume status, especially in patients admitted to the intensive care units, and more recently, for guiding fluid removal in the outpatient dialysis units. Fundamental knowledge of sonography has become invaluable to the nephrologist, and performance and interpretation of ultrasound has now become an essential tool for practicing nephrologists to provide patient-centered care, maximize efficiency, and minimize fragmentation of care. This review will address the growing role of ultrasonography in the management of a patient with CKD from the point of initial contact with the nephrologist throughout the spectrum of kidney disease and its consequences.

Manual erythroexchange in sickle cell disease: multicenter validation of a protocol predictive of volume to exchange and hemoglobin values.

Manual erythroexchange (MEEX) was proven to be effective and safe in the management of sickle cell disease (SCD). The goal is to quickly reduce the percentage of hemoglobin S (HbS%). A national survey of the Italian Society for Thalassemia and Hemoglobinopathies (SITE) observed a great variability among MEEX protocols none of which were found to be predictive of the values of HbS% and hemoglobin (Hb) after the exchange. Two equations to estimate the HbS% and Hb values to be obtained after MEEX were developed based on the results of the MEEX procedures in place in the centers participating in the present study. A standard protocol was subsequently defined to evaluate the volumes to exchange to obtain the target values of HbS% and Hb. The protocol was tested in 261 MEEX performed in SCD patients followed in the 5 participating centers that belong to the Italian Hemoglobinopathy Comprehensive Care Network, with the support of the SITE. The results showed a correlation between the estimated and measured values of HbS% and Hb (Rp 0.95 and 0.65 respectively, p < 0.001). A negligible bias was found for the prediction of HbS% and a bias of 1 g/dl for Hb. From consecutive MEEX, a rate of increase of HbS% between two exchanges of around 0.4% per day (p < 0.001) was measured. This protocol was shown to be effective and safe, as all patients reached the target value of HbS%. All the MEEX procedures were carried out with single venous access. No adverse events or reactions such as hypotension or electrolyte imbalance were reported nor were any complaints concerning the procedures received from patients.

Perfusion-guided sonopermeation of neuroblastoma: a novel strategy for monitoring and predicting liposomal doxorubicin uptake in vivo.

Neuroblastoma (NB) is the most common extracranial solid tumor in infants and children, and imposes significant morbidity and mortality in this population. The aggressive chemoradiotherapy required to treat high-risk NB results in survival of less than 50%, yet is associated with significant long-term adverse effects in survivors. Boosting efficacy and reducing morbidity are therefore key goals of treatment for affected children. We hypothesize that these may be achieved by developing strategies that both focus and limit toxic therapies to the region of the tumor. One such strategy is the use of targeted image-guided drug delivery (IGDD), which is growing in popularity in personalized therapy to simultaneously improve on-target drug deposition and assess drug pharmacodynamics in individual patients. IGDD strategies can utilize a variety of imaging modalities and methods of actively targeting pharmaceutical drugs, however in vivo imaging in combination with focused ultrasound is one of the most promising approaches already being deployed for clinical applications. Over the last two decades, IGDD using focused ultrasound with "microbubble" ultrasound contrast agents (UCAs) has been increasingly explored as a method of targeting a wide variety of diseases, including cancer. This technique, known as sonopermeation, mechanically augments vascular permeability, enabling increased penetration of drugs into target tissue. However, to date, methods of monitoring the vascular bioeffects of sonopermeation in vivo are lacking. UCAs are excellent vascular probes in contrast-enhanced ultrasound (CEUS) imaging, and are thus uniquely suited for monitoring the effects of sonopermeation in tumors. Methods: To monitor the therapeutic efficacy of sonopermeation in vivo, we developed a novel system using 2D and 3D quantitative contrast-enhanced ultrasound imaging (qCEUS). 3D tumor volume and contrast enhancement was used to evaluate changes in blood volume during sonopermeation. 2D qCEUS-derived time-intensity curves (TICs) were used to assess reperfusion rates following sonopermeation therapy. Intratumoral doxorubicin (and liposome) uptake in NB was evalauted ex vivo along with associated vascular changes. Results: In this study, we demonstrate that combining focused ultrasound therapy with UCAs can significantly enhance chemotherapeutic payload to NB in an orthotopic xenograft model, by improving delivery and tumoral uptake of long-circulating liposomal doxorubicin (L-DOX) nanoparticles. qCEUS imaging suggests that changes in flow rates are highly sensitive to sonopermeation and could be used to monitor the efficacy of treatment in vivo. Additionally, initial tumor perfusion may be a good predictor of drug uptake during sonopermeation. Following sonopermeation treatment, vascular biomarkers show increased permeability due to reduced pericyte coverage and rapid onset of doxorubicin-induced apoptosis of NB cells but without damage to blood vessels. Conclusion: Our results suggest that significant L-DOX uptake can occur by increasing tumor vascular permeability with microbubble sonopermeation without otherwise damaging the vasculature, as confirmed by in vivo qCEUS imaging and ex vivo analysis. The use of qCEUS imaging to monitor sonopermeation efficiency and predict drug uptake could potentially provide real-time feedback to clinicians for determining treatment efficacy in tumors, leading to better and more efficient personalized therapies. Finally, we demonstrate how the IGDD strategy outlined in this study could be implemented in human patients using a single case study.

Correlation of Quantitated Intravascular Volume with Blood Pressure in Patients with Systemic Hypertension.

Volume management is an essential component of anti-hypertensive therapy. Different volume phenotypes have been proposed. We sought to study the total blood volume (TBV), plasma volume (PV), and red blood cell volume (RBV) in hypertensive patients. We included patients followed in an outpatient cardiology clinic from 1998 to 2003. Blood volume (BV) parameters were measured using radioisotope iodine-131-labeled albumin dilution technique. Values were expressed as percentage (%) deviation from ideal volumes. A total of 95 patients were included. The intravascular volume distribution as percent deviation from normal volume ranged from - 23 to + 28% for TBV, - 22 to + 36% for PV and - 29 to + 37% for RBV. There was no significant correlation between systolic BP and any of the BV parameters (TBV and SBP, r = - 0.03; PV and SBP, r = - 0.12; RBV and SBP, r = - 0.08). Patients with hypertension have a wide variation in BV parameters. BV does not correlate with SBP.

Clinical Application of Apheresis in Very Small Dogs Weighing <8 kg to Pediatric Patients.

Apheresis in low body weight children and adolescents is challenging due to a variety of technical and clinical issues including vascular access, low total blood volume, and hypotension. Although dogs have been a valuable preclinical model for apheresis, the procedure can be challenging since many pure-bred dogs are extremely small. Therefore, apheresis in these very small breeds presents very similar challenges as seen when performing the procedure in very low body weight people. We describe apheresis of four very small dogs, weighing from 4.6 to 7.6 kg, using either a COBESpectra and Spectra Optia apheresis system (Terumo BCT, Lakewood, CO, USA). Two dogs underwent large volume leukapheresis to collect mononuclear cells in preparation for hematopoietic stem cell transplantation and two dogs underwent therapeutic plasma exchange to treat an immune-mediated disease. In all cases, a dual-lumen hemodialysis catheter placed in the jugular vein provided adequate machine inlet and return flow rates. Machine priming was necessary to maintain hemodynamic stability during the beginning of the procedure, and rinseback was avoided for the same reason. Anticoagulant citrate dextrose solution, solution A was used for the large volume leukapheresis procedures and a combination of anticoagulant citrate dextrose solution, solution A and heparin was used for the therapeutic plasma exchange procedures. As such, serum iCa levels were regularly monitored and 10% calcium gluconate constant rate infusions were used to prevent citrate toxicity. All dogs completed the aphereses with no life-threatening adverse events. We conclude that aphereses in very small dogs is feasible if close attention is paid to hemodynamic stability and citrate toxicity.

Multifrequency Analysis of Single Inductive Coil Measurements Across a Gel Phantom Simulation of Internal Bleeding in the Brain.

The present study is part of an ongoing effort to develop a simple diagnostic technology for detecting internal bleeding in the brain, which can be used in lieu or in support of medical imaging and thereby reduce the cost of diagnostics in general, and in particular, would make diagnostics accessible to economically disadvantaged populations. The study deals with a single coil inductive device to be used for detecting cerebral hemorrhage. It presents a first-order experimental study that examines the predictions of our recently published theoretical study. The experimental model employs a homogeneous cylindrical phantom in which internal head bleeding was simulated by way of a fluid inclusion. We measured the changes in amplitude and phase across the coil with a network vector analyzer as a function of frequency (100-1,000 MHz), volume of blood simulating fluid, and the site of the fluid injection. We have developed a new mathematical model to statistically analyze the complex data produced in this experiment. We determined that the resolution for the fluid volume increase following fluid injection is strongly dependent on frequency as well as the location of liquid accumulation. The experimental data obtained in this study supports the predictions of our previous theoretical study, and the statistical analysis shows that the simple single coil device is sensitive enough to detect changes due to fluid volume alteration of two milliliters. Bioelectromagnetics. 2020;41:21-33 © 2019 Bioelectromagnetics Society.

Vascular Pressure-Flow Measurement Using CB-PDMS Flexible Strain Sensor.

Regular monitoring of blood flow and pressure in vascular reconstructions or grafts would provide early warning of graft failure and improve salvage procedures. Based on biocompatible materials, we have developed a new type of thin, flexible pulsation sensor (FPS) which is wrapped around a graft to monitor blood pressure and flow. The FPS uses carbon black (CB) nanoparticles dispersed in polydimethylsiloxane (PDMS) as a piezoresistive sensor layer, which was encapsulated within structural PDMS layers and connected to stainless steel interconnect leads. Because the FPS is more flexible than natural arteries, veins, and synthetic vascular grafts, it can be wrapped around target conduits at the time of surgery and remain implanted for long-term monitoring. In this study, we analyze strain transduction from a blood vessel and characterize the electrical and mechanical response of CB-PDMS from 0-50% strain. An optimum concentration of 14% CB-PDMS was used to fabricate 300-µm thick FPS devices with elastic modulus under 500 kPa, strain range of over 50%, and gauge factor greater than 5. Sensors were tested in vitro on vascular grafts with flows of 0-1,100 mL/min. In vitro testing showed linear output to pulsatile flows and pressures. Cyclic testing demonstrated robust operation over hundreds of cardiac cycles, with ±2.6 mmHg variation in pressure readout. CB-PDMS composite material showed excellent potential in biologic strain sensing applications where a flexible sensor with large maximum strain range is needed.

Utility of Percentage Signal Recovery and Baseline Signal in DSC-MRI Optimized for Relative CBV Measurement for Differentiating Glioblastoma, Lymphoma, Metastasis, and Meningioma.

BACKGROUND AND PURPOSE: The percentage signal recovery in non-leakage-corrected (no preload, high flip angle, intermediate TE) DSC-MR imaging is known to differ significantly for glioblastoma, metastasis, and primary CNS lymphoma. Because the percentage signal recovery is influenced by preload and pulse sequence parameters, we investigated whether the percentage signal recovery can still differentiate these common contrast-enhancing neoplasms using a DSC-MR imaging protocol designed for relative CBV accuracy (preload, intermediate flip angle, low TE). MATERIALS AND METHODS: We retrospectively analyzed DSC-MR imaging of treatment-naïve, pathology-proved glioblastomas (n = 14), primary central nervous system lymphomas (n = 7), metastases (n = 20), and meningiomas (n = 13) using a protocol designed for relative CBV accuracy (a one-quarter-dose preload and single-dose bolus of gadobutrol, TR/TE = 1290/40 ms, flip angle = 60° at 1.5T). Mean percentage signal recovery, relative CBV, and normalized baseline signal intensity were compared within contrast-enhancing lesion volumes. Classification accuracy was determined by receiver operating characteristic analysis. RESULTS: Relative CBV best differentiated meningioma from glioblastoma and from metastasis with areas under the curve of 0.84 and 0.82, respectively. The percentage signal recovery best differentiated primary central nervous system lymphoma from metastasis with an area under the curve of 0.81. Relative CBV and percentage signal recovery were similar in differentiating primary central nervous system lymphoma from glioblastoma and from meningioma. Although neither relative CBV nor percentage signal recovery differentiated glioblastoma from metastasis, mean normalized baseline signal intensity achieved 86% sensitivity and 50% specificity. CONCLUSIONS: Similar to results for non-preload-based DSC-MR imaging, percentage signal recovery for one-quarter-dose preload-based, intermediate flip angle DSC-MR imaging differentiates most pair-wise comparisons of glioblastoma, metastasis, primary central nervous system lymphoma, and meningioma, except for glioblastoma versus metastasis. Differences in normalized post-preload baseline signal for glioblastoma and metastasis, reflecting a snapshot of dynamic contrast enhancement, may motivate the use of single-dose multiecho protocols permitting simultaneous quantification of DSC-MR imaging and dynamic contrast-enhanced MR imaging parameters.