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.

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.

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.

Rodent Cerebral Blood Volume (CBV) changes during hypercapnia observed using Magnetic Particle Imaging (MPI) detection.

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 new method for the assessment of endothelial function with peripheral arterial volume.

BACKGROUND: Currently, many methodological approaches have been developed to assess peripheral endothelial function. However, a development of the noninvasive and automated technique for routinely assessing endothelial function is still required. We evaluated the potential value of a new method to measure peripheral endothelial function with reactive hyperemia peripheral arterial volume (RH-PAV) in patients with chest pain. METHODS: We used a novel oximeter-like probe to detect the peripheral arterial volume (PAV) of the finger and compared it with brachial flow-mediated dilation (FMD) performed in 93 consecutive patients with chest pain. The RH-PAV index was defined as the ratio of the digital pulse volume during reactive hyperemia relative to the baseline. RESULTS: Ninety-three patients (53 men, 58 ± 5 years) completed the study, and 53 patients demonstrated coronary artery disease (CAD) following scheduled coronary angiography. There was a moderate linear relationship between PAV and FMD (r = 0.69, p < 0.01). Similar to FMD, PAV was more impaired in patients who have more cardiovascular risk factors (CRFs). The subjects with CAD had lower PAV and FMD, compared with those without CAD (1.05 ± 0.23 VS. 1.41 ± 0.37, p < 0.01; 6.7% ± 2.9% VS. 10.4% ± 2.9%, p < 0.01, respectively), and the relationships between FMD and PAV were also significant in both CAD (r = 0.54, p < 0.01) and non-CAD (r = 0.62, p < 0.01) patients. CONCLUSIONS: Endothelial function of digital artery assessed with the novel PAV method demonstrated a profile similar to that of brachial artery measured with FMD. The hyperemia PAV was decreased by factors which were considered to impair endothelial function, suggesting that PAV has the potential to be a novel method to study endothelial function.

Reliability and validity of non-invasive determined haemoglobin mass and blood volumes.

INTRODUCTION: The carbon monoxide (CO) rebreathing method used for the determination of haemoglobin mass (Hbmass ) is associated with blood sample analysis (in this study: Radiometer ABL800). As an alternative hereto the aim of the present study was to evaluate the use of a portable and non-invasive CO pulse oximeter (Rad-57). METHOD: With simultaneous determination of CO in the circulation by ABL800 (%HbCO) and Rad-57 (SpCO), Hbmass and blood volume (BV) were determined in duplicates in 24 volunteers. Percentage of typical errors (%TE) within methods and linear correlations between the two procedures were computed. RESULTS: Hbmass (Rad-57 = 798 ± 230 g; ABL800 = 781 ± 192 g) and BV (Rad-57 = 5700 ± 1373 ml; ABL800 = 5581 ± 1096 ml) were similar between methods. However, the %TE for Hbmass was higher (P<0·001) for Rad-57 (5·84 ± 5·29%) than for ABL800 (1·35 ± 1·13%). Similarly, the %TE for BV was higher (P<0·001) for Rad-57 (6·06 ± 5·76%) than for ABL800 (1·48 ± 1·25%). Lower (P<0·05) correlation coefficients between the methods were found when Hbmass  > 905 g and BV > 6193 ml. CONCLUSION: Assessment of SpCO by Rad-57 resulted in considerably less precise determinations of Hbmass and BV, especially for high values. Thus, non-invasive assessment of Hbmass and BV cannot be recommended for scientific purposes, but may nonetheless be useful in clinical settings.

An Online Module to Understand Body Fluid Status in Clinical Cases.

Introduction: A thorough understanding of body fluid alterations is essential for the success of both practicing dentists and physicians. However, the time constraints of professional school curricula often limit the time available in physiology courses to address this material. Methods: The primary goal of this resource was to improve student comprehension of body fluid status by using three online videos that explain volume-osmolality diagrams. An additional goal was to improve students' ability to apply their physiological knowledge by showcasing real-life clinical situations in medicine and dentistry. The videos were created using custom-designed PowerPoint animations, video recordings, and Camtasia video-editing software. Results: On assessment of exam performance, students performed similarly in sections of the course that were taught using the online modules versus face-to-face lectures. Student performance was extremely high on the body fluid assessment-questions, with an average of 95%. This high level of student performance was notable, particularly given the complexity of the questions. Discussion: These results indicate that this online volume-osmolality module enabled students to improve their comprehension of body fluid concepts in physiology. Furthermore, the data indicates the feasibility of replacing lectures with online modules, freeing valuable class time for active learning or more advanced physiological concepts.

Investigation of Ultrasound-Measured Flow Rate and Wall Shear Rate in Wrist Arteries Using Flow Phantoms.

The aim of this study was to evaluate the errors in measurement of volumetric flow rate and wall shear rate measured in radial and ulnar arteries using a commercial ultrasound scanning system. The Womersley equations were used to estimate the flow rate and wall shear rate waveforms, based on the measured vessel diameter and centerline velocity waveform. In the experiments, each variable (vessel depth, diameter, flow rate, beam-vessel angle and different waveform) in the phantom was investigated in turn, and its value was varied within a normal range while others were fixed at their typical values. The outcomes revealed that flow rate and wall shear rate were overestimated in all cases, from around 13% to nearly 50%. It is concluded that measurements of flow rate and wall shear rate in radial and ulnar arteries with a clinical ultrasound scanner are vulnerable to overestimation.

Effects of Osmotic Changes on Measuring Relative Blood Volume: Comparison of Three Hemodialysis Devices.

Recording the relative blood volume is a standard feature of modern dialysis devices. Three different measurement systems are incorporated in currently available dialysis machines. The Gambro-Hospal group and Nikkiso feature blood volume monitors based on different optical methods. The Fresenius Medical Care machines perform blood volume monitoring with an ultrasonic method. On grounds of clinical evidence suggesting a malfunction of the optical methods in the presence of sodium changes, we compared these three systems. Under the tested conditions, both optical systems show opposite and nonplausible courses of blood volume changes. The ultrasonic system seems to be less susceptible to osmotic changes.

Optoelectronic system for the determination of blood volume in pneumatic heart assist devices.

BACKGROUND: The following article describes the concept of optical measurement of blood volume in ventricular assist devices (VAD's) of the pulsatile type. The paper presents the current state of art in blood volume measurements of such devices and introduces a newly developed solution in the optic domain. The objective of the research is to overcome the disadvantages of the previously developed acoustic method-the requirement of additional sensor chamber. METHODS: The idea of a compact measurement system has been introduced, followed by laboratory measurements. Static tests of the system have been presented, followed by dynamic measurements on a physical model of the human ventricular system. The results involving the measurements of blood chamber volume acquired by means of an optical system have been compared with the results acquired by means of the Transonic T410 ultrasound flow rate sensor (11PLX transducer, uncertainty ±5 %). RESULTS: Preliminary dynamic measurements conducted on the physical model of the human cardiovascular system show that the proposed optical measurement system may be used to measure the transient blood chamber volumes of pulsatile VAD's with the uncertainties (standard mean deviation) lower than 10 %. CONCLUSIONS: The results show that the noninvasive measurements of the temporary blood chamber volume in the POLVAD prosthesis with the use of the developed optical system allows us to carry out accurate static and dynamic measurements.

Evaluation of the BD BACTEC FX blood volume monitoring system as a continuous quality improvement measure.

The yield of blood cultures is proportional to the volume of blood cultured. We evaluated an automatic blood volume monitoring system, recently developed by Becton Dickinson within its BACTEC EpiCenter module, that calculates mean volumes of negative aerobic bottles and generates boxplots and histograms. First, we evaluated the filling degree of 339 aerobic glass blood cultures by calculating the weight-based volume for each bottle. A substantial amount of the bottles (48.3%) were inadequately filled. Evaluation of the accuracy of the monitoring system showed a mean bias of -1.4 mL (-15.4%). Additional evaluation, using the amended software on 287 aerobic blood culture bottles, resulted in an acceptable mean deviation of -0.3 mL (-3.3%). The new software version was also tested on 200 of the recently introduced plastic bottles, which will replace the glass bottles in the near future, showing a mean deviation of +2.8 mL (+26.7%). In conclusion, the mean calculated volumes can be used for the training of a single phlebotomist. However, filling problems appear to be masked when using them for phlebotomist groups or on wards. Here, visual interpretation of boxplots and histograms can serve as a useful tool to observe the spread of the filling degrees and to develop a continuous improvement program. Re-adjustment of the software has proven to be necessary for use with plastic bottles. Due to our findings, BD has developed further adjustments to the software for validated use with plastic bottles, which will be released soon.

Hepatic blood volume imaging with the use of flat-detector CT perfusion in the angiography suite: comparison with results of conventional multislice CT perfusion.

PURPOSE: To prospectively determine the feasibility of flat-detector (FD) computed tomography (CT) perfusion to measure hepatic blood volume (BV) in the angiography suite in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty patients with HCC were investigated with conventional multislice and FD CT perfusion. CT perfusion was carried out on a multislice CT scanner, and FD CT perfusion was performed on a C-arm angiographic system, before transarterial chemoembolization procedures. BV values of conventional and FD CT perfusion were measured within tumors and liver parenchyma. The arterial perfusion portion of CT perfusion BV was extracted from CT perfusion BV by multiplying it by a hepatic perfusion index. Relative values (RVs) for CT perfusion arterial BV and FD CT perfusion BV (FD BV) were defined by dividing BV of tumor by BV of parenchyma. Relationships between BV and RV values of these two techniques were analyzed. RESULTS: In all patients, both perfusion procedures were technically successful, and all 33 HCCs larger than 10 mm were identified with both imaging methods. There were strong correlations between the absolute values of FD BV and CT perfusion arterial BV (tumor, r = 0.903; parenchyma, r = 0.920; both P < .001). Bland-Altman analysis showed a mean difference of -0.15 ± 0.24 between RVs for CT perfusion arterial BV and FD BV. CONCLUSIONS: The feasibility of FD CT perfusion to assess BV values of liver tumor and surrounding parenchyma in the angiographic suite was demonstrated.

Novel method for early signs of clinical shock detection by monitoring blood capillary/vessel spatial pattern.

The ability to monitor capillary/vessel spatial patterns and local blood volume fractions is critical in clinical shock detection and its prevention in Intensive Care Units (ICU). Although the causes of shock might be different, the basic abnormalities in pathophysiological changes are the same. To detect these changes, we have developed a novel method based on both spectrally and spatially resolved diffuse reflectance spectra. The preliminary study has shown that this method can monitor the spatial distribution of capillary/vessel spatial patterns through local blood volume fractions of reduced hemoglobin and oxyhemoglobin. This method can be used as a real-time and non-invasive tool for the monitoring of shock development and feedback on the therapeutic intervention.

Radiation doses of cerebral blood volume measurements using C-arm CT: A phantom study.

BACKGROUND AND PURPOSE: Parenchymal blood volume measurement by C-arm CT facilitates in-room peritherapeutic perfusion evaluation. However, the radiation dose remains a major concern. This study aimed to compare the radiation dose of parenchymal blood volume measurement using C-arm CT with that of conventional CTP using multidetector CT. MATERIALS AND METHODS: A biplane DSA equipped with C-arm CT and a Rando-Alderson phantom were used. Slab parenchymal blood volume (8-cm scanning range in a craniocaudal direction) and whole-brain parenchymal blood volume with identical scanning parameters, except for scanning ranges, were undertaken on DSA. Eighty thermoluminescent dosimeters were embedded into 22 organ sites of the phantom. We followed the guidelines of the International Commission on Radiation Protection number 103 to calculate the effective doses. For comparison, 8-cm CTP with the same phantom and thermoluminescent dosimeter distribution was performed on a multidetector CT. Two repeat dose experiments with the same scanning parameters and phantom and thermoluminescent dosimeter settings were conducted. RESULTS: Brain-equivalent dose in slab parenchymal blood volume, whole-brain parenchymal blood volume, and CTP were 52.29 ± 35.31, 107.51 ± 31.20, and 163.55 ± 89.45 mSv, respectively. Variations in the measurement of an equivalent dose for the lens were highest in slab parenchymal blood volume (64.5%), followed by CTP (54.6%) and whole-brain parenchymal blood volume (29.0%). The effective doses of slab parenchymal blood volume, whole-brain parenchymal blood volume, and CTP were 0.87 ± 0.55, 3.91 ± 0.78, and 2.77 ± 1.59 mSv, respectively. CONCLUSIONS: The dose measurement conducted in the current study was reliable and reproducible. The effective dose of slab parenchymal blood volume is about one-third that of CTP. With the advantages of on-site and immediate imaging availability and saving procedural time and patient transportation, slab parenchymal blood volume measurement using C-arm CT can be recommended for clinical application.

A new menstrual pictogram for use with feminine products that contain superabsorbent polymers.

OBJECTIVE: To determine whether the menstrual pictogram (the superabsorbent polymer-c or SAP-c version) can reliably estimate blood and total menstrual fluid volumes on prestained Always Ultra slim feminine towels (Proctor & Gamble) that contain superabsorbent polymers. DESIGN: Randomized blinded study using simulated menstrual fluid (SMF: 50% blood, 50% saline mixture). SETTING: Gynecology research clinic. PATIENT(S): 12 premenopausal women with regular menstrual cycles who had not previously used a graphical method to assess menstrual loss. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Assignment of 135 prestained towels containing known volumes of 0.5-25.0 mL of SMF to five pictorial icons of the menstrual pictogram, and correlation of pictogram scores to blood recovered from towels by the alkaline hematin method and total fluid applied to towels by measurement of soiled towel weight. RESULT(S): There was a high level of agreement between individual scores. For 112 (83%) of 135 towels, the participants' readings either completely concurred or differed by only a single icon. There was a statistically significant correlation between the volume of blood applied (SMF/2) and that recovered by alkaline hematin, and volume of fluid applied and soiled towel weight. CONCLUSION(S): The menstrual pictogram (SAP-c version) is a potential diagnostic tool for heavy menstrual bleeding and would be suitable for testing in a clinical trial.

Laser doppler blood flow imaging using a CMOS imaging sensor with on-chip signal processing.

The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue.

Sensitivity of blood volume monitoring for fluid status assessment in hemodialysis patients.

BACKGROUND/AIMS: This study investigates the use of blood volume monitoring (BVM) markers for the assessment of fluid status. METHODS: Predialysis fluid overload (FO) and BVM data were collected in 55 chronic hemodialysis patients in 317 treatments. Predialysis FO was measured using bioimpedance spectroscopy. The slope of the intravascular volume decrease over time normalized by ultrafiltration rate (Slope4h) was used as the primary BVM marker and compared against FO. RESULTS: Average relative blood volume curves were well separated in different FO groups between 0 and 5 liters. Receiver-operating characteristics analysis revealed that the sensitivity of BVM was moderate in median FO ranges between 1 and 3 liters (AUC 0.60-0.65), slightly higher for volume depletion of FO <1 liter (AUC 0.7) and highest for excess fluid of FO >3 liters (AUC 0.85). CONCLUSION: Devices that monitor blood volume are well suited to detect high FO, but are not as sensitive at moderate or low levels of fluid status.

Sensors and hybrid therapies: a new approach with automated citrate anticoagulation.

BACKGROUND: Hybrid therapies use intermittent hemodialysis (IHD) machines adapted to provide prolonged intermittent or continuous renal replacement therapy in the intensive care unit (ICU). Despite the low cost, hybrid therapy use is limited warranting a novel approach. METHODS: The literature was reviewed for limitations of hybrid protocols, use of regional citrate anticoagulation (RCA) on hybrid systems and sensors for IHD and hybrid therapy. The novel hybrid program in the authors' institution is presented as a plausible future direction for the modality. RESULTS: Hybrid therapies are limited by access flow and clotting alarms. Technology limitations render many IHD sensors inoperable at low dialysate flow. A synergy with RCA allows a novel, safe approach with low blood flows and high dialysate flows with alarm- and clotting-free operation and all commercial IHD sensors functional. CONCLUSION: The low cost, ease of use, safety and efficacy of hybrid therapy with near-automated RCA may lead to rapid expansion of this form of ICU renal support.

Haemodynamic parameters and cognitive function during modeled acute volume loss.

PURPOSE: The purpose of the present study was to find a noninvasive way of detecting even smaller volume loss which is easier to carry out and possibly more precise than the currently used (mostly sphygmomanometer-based) methods. Haemodynamic and EEG measurements were carried out in simulated volume loss, involving blood donation and orthostatic challenges to assess adaptive responses and cognitive performance. Cognitive performance was assessed in an oddball task and changes of the evoked potential P300 were analyzed. Both haemodynamic and cognitive parameters were recorded in 'pre-donation' and 'post-donation' conditions for purposes of comparison. RESULTS: Cognitive performance (as reflected by P300 changes) was found to be a poor marker of volume loss. Difference between the two conditions in none of the parameters reached the level of statistical significance (defined as p < 0.05) RR mean, baroreceptor sensitivity and pulse pressure were rather sensitive to the relatively mild volume loss (p < 0.01 between pre- and post-conditions). CONCLUSION: Our study indicates that traditional sphygmomanometer based values can safely be replaced by values yielded by finger plethysmography, combined with brief orthostatic challenges and that P300 as a cognitive marker cannot be used to assess volume loss.