Blood Volume Research Articles

Diuretic responses to Ringer's solution and 20% albumin at different arterial pressures.

Intravenous volume loading is a common treatment when hypovolemia is a potential cause of oliguria. We studied whether the effectiveness of Ringer's solution and 20% albumin in inducing diuresis differs depending on the mean arterial pressure (MAP). For this purpose, volume kinetic analysis was performed based on urine output and hemoglobin-derived plasma dilution obtained during and after 136 infusions of Ringer and 85 infusions of 20% albumin. Covariance analysis quantified the diuretic response at different arterial pressures. The results show that the diuretic response to a known plasma volume expansion was greater for Ringer's solution above a MAP of 70 mmHg, while 20% albumin was significantly more effective at lower pressures (p < 0.03). Simulations of the urinary output in response to infusion of a predefined fluid volume yielded superior efficacy for 20% albumin when the MAP was low, while Ringer's was similarly effective when the MAP averaged 100 mmHg. In conclusion, urine output in response to plasma volume expansion with 20% albumin was similar to, or even stronger, than that of Ringer's solution when the MAP was below 70 mmHg.

Correlating stroke risk with non-invasive cerebrovascular perfusion dynamics using a portable speckle contrast optical spectroscopy laser device

Stroke poses a significant global health threat, with millions affected annually, leading to substantial morbidity and mortality. Current stroke risk assessment for the general population relies on markers such as demographics, blood tests, and comorbidities. A minimally invasive, clinically scalable, and cost-effective way to directly measure cerebral blood flow presents an opportunity. This opportunity has the potential to positively impact effective stroke risk assessment prevention and intervention. Physiological changes in the cerebrovascular system, particularly in response to hypercapnia and hypoxia during voluntary breath-holding can offer insights into stroke risk assessment. However, existing methods for measuring cerebral perfusion reserves, such as blood flow and blood volume changes, are limited by either invasiveness or impracticality. Herein we propose a non-invasive transcranial approach using speckle contrast optical spectroscopy (SCOS) to non-invasively monitor regional changes in brain blood flow and volume during breath-holding. Our study, conducted on 50 individuals classified into two groups (low-risk and higher-risk for stroke), shows significant differences in blood dynamic changes during breath-holding between the two groups, providing physiological insights for stroke risk assessment using a non-invasive quantification paradigm. Given its cost-effectiveness, scalability, portability, and simplicity, this laser-centric tool has significant potential for early diagnosis and treatment of stroke in the general population.

Plasma volume response patterns and a physiologic model of ultrafiltration in hemodialysis.

Ultrafiltration (UF) is an essential process of restoring fluid homeostasis during hemodialysis (HD). Fluid shifts across the extracellular compartments during UF, predominantly across the capillary interface and between the macro- and microcirculation. A mismatch between UF and transcapillary fluid transport can lead to hemodynamic instability leading to cardiac morbidity. We wished to study intradialytic fluid transport characteristics and their variation during UF to identify factors that govern variability in transcapillary fluid movement in HD. Twenty-two patients undergoing stable HD sessions were studied to measure and monitor absolute blood and plasma volume throughout UF. A computational mathematical model of predicted plasma volume decay during UF was analyzed with respect to the intradialytic real-time data profile. Pre- and post-dialysis fluid status was assessed using multifrequency bioimpedance spectroscopy. Serum electrolytes, osmolality, and total protein concentration were measured pre- and post-dialysis and during the intradialytic phase. Two distinct profiles of PV responses were detected. 60% of the patients presented plasma volume decline, characterized by a high percentage of volume decrease during the first hour, and a subsequent slower decrease with early rebound. The model was modified to achieve a proper fit of these volume profiles, assuming time-dependent changes in selected parameters governing the refilling flow. Although the modified model could more accurately fit the data, the new parameter values often fell outside of a physiologically acceptable range, suggesting that other factors not included in the classic description of transcapillary fluid transport might be the cause of the observed patterns.

Effects of 90-Minute Football Match on Red Blood Indices in Sedentary Young Males

While exercise-induced haemorheological alterations are well-documented in various sports, the specific impact of a football match on red blood cell (RBC) parameters remains unknown. This study investigates the acute effects of a 90-minute football match on RBC indices in sedentary young males. After inclusion and exclusion criteria, twenty (20) moderately active, non-smoking male volunteers (mean age: 20.00 ± 0.4 years) participated in the study. Venous blood samples were collected pre- and post- football match to assess RBC count, haematocrit (HCT), and plasma volume (PV). Data generated were subjected to paired student's t-tests using SPSS, to compare values between pre- and post-match measurements. A p-value of less than 0.05 was considered indicative of statistical significance. The results showed a statistically significant decrease in haematocrit (HCT) and red blood cell count (RBC) after the match (p &lt; 0.05) when compared to pre-match values. This was accompanied by a significant increase in plasma volume (PV) (p &lt; 0.05), which was higher than pre-match values. These changes suggest that the physiological demands of the football match influenced blood parameters, likely due to fluid shifts and haemodilution during intense physical activity. These findings suggest potential implications for exercise physiology, diagnosis, and therapy in sports medicine.

U-Net-based computed tomography quantification of viral pneumonia can predict fibrotic interstitial lung abnormalities at 3-month follow-up

BackgroundGiven the high prevalence of fibrotic interstitial lung abnormalities (ILAs) post-COVID-19, this study aims to evaluate the effectiveness of quantitative CT features in predicting fibrotic ILAs at 3-month follow-up.MethodsThis retrospective study utilized cohorts from distinct clinical settings: the training dataset comprised individuals presenting at the fever clinic and emergency department, while the validation dataset included patients hospitalized with COVID-19 pneumonia. They were classified into fibrotic group and nonfibrotic group based on whether the fibrotic ILAs were present at follow-up. A U-Net-based AI tool was used for quantification of both pneumonia lesions and pulmonary blood volumes. Receiver operating characteristic (ROC) curve analysis and multivariate analysis were used to assess their predictive abilities for fibrotic ILAs.ResultsAmong the training dataset, 122 patients (mean age of 68 years ±16 [standard deviation], 73 men), 55.74% showed fibrotic ILAs at 3-month follow-up. The multivariate analysis identified the pneumonia volume [PV, odd ratio (OR) 3.28, 95% confidence interval (CI): 1.20–9.31, p = 0.02], consolidation volume (CV, OR 3.77, 95% CI: 1.37–10.75, p = 0.01), ground-glass opacity volume (GV, OR 3.38, 95% CI: 1.26–9.38, p = 0.02), pneumonia mass (PM, OR 3.58, 95% CI: 1.28–10.46, p = 0.02), and the CT score (OR 12.06, 95% CI: 3.15–58.89, p &amp;lt; 0.001) as independent predictors of fibrotic ILAs, and all quantitative parameters were as effective as CT score (all p &amp;gt; 0.05). And the area under the curve (AUC) values were PV (0.79), GV (0.78), PM (0.79), CV (0.80), and the CT score (0.77). The validation dataset, comprising 45 patients (mean age 67.29 ± 14.29 years, 25 males) with 57.78% showing fibrotic ILAs at follow-up, confirmed the predictive validity of these parameters with AUC values for PV (0.86), CV (0.90), GV (0.83), PM (0.88), and the CT score (0.85). Additionally, the percentage of blood volume in vessels &amp;lt;5mm2 relative to the total pulmonary blood volume (BV5%) was significantly lower in patients with fibrotic ILAs (p = 0.048) compared to those without.ConclusionU-Net based quantification of pneumonia lesion and BV5% on baseline CT scan has the potential to predict fibrotic ILAs at follow-up in COVID-19 patients.

Effects of Transjugular Intrahepatic Portosystemic Shunt on Renal and Pulmonary Function in Hepatic Decompensation with and without Hepatorenal and Hepatopulmonary Syndromes: A Review.

Cirrhosis is often characterized by decreased liver function, ranging from a compensated, typically asymptomatic phase to a decompensated phase characterized by the appearance of ascites or variceal bleeding, and ultimately hepatorenal syndrome (HRS) or hepatopulmonary syndrome (HPS). The latter two complications are associated with a poor prognosis and limited treatment efficacy. In cases of ascites or variceal bleeding resistant to medical therapy, transjugular intrahepatic portosystemic shunt (TIPS) is effective and safe. Shunting blood by TIPS diverts portal blood to the systemic circulation, potentially increasing systemic blood volume and benefiting renal function. However, TIPS could also divert nitric oxide to the systemic circulation, potentially worsening systemic hypotension and perfusion, which could be detrimental to renal function. Available evidence indicates that TIPS often improves renal function in patients with portal hypertension, with or without HRS. No studies have shown persistently decreased renal function after TIPS. However, these data are insufficient to support a recommendation for the use of TIPS specifically for HRS. In patients without pre-existing HPS, TIPS does not appear to significantly affect pulmonary gas exchange. Results of TIPS in HPS have been inconsistent; some studies have shown improvement, but effects were transient. No studies have shown a persistent decline in pulmonary function after TIPS. The evidence supports the need for large randomized controlled trials to investigate the beneficial effects of TIPS for HRS. Similar pulmonary function data are less clear regarding TIPS for HPS. The aim of the current report was to review the literature regarding the effects of TIPS on renal and pulmonary function in hepatic decompensation, with or without the development of HRS or HPS.

Blood volume collected for cultures in infants with suspected neonatal sepsis.

To evaluate blood culture sample volumes, identify factors linked to insufficient samples, and compare volumes among neonates treated for culture-negative-sepsis, sepsis-rule-outs, and bloodstream infections (BSI). Observational cohort of blood cultures collected during NICU stay. Association of age, weight, gender, source, and collection time with lower-than-recommended volumes was determined by logistic regression. Blood culture inocula of patients with culture-negative-sepsis, sepsis rule-out, and BSI were compared using ANOVA. 742 blood cultures were obtained from 292 neonates. Median inoculum was 1 mL (IQR:0.6-1.4), and 259 bottles (35%) had inocula <0.9 mL. Night shift sample collection was associated with lower-than-recommended volumes (p = 0.006). No difference in sample volumes was observed between culture-negative-sepsis, sepsis-rule-outs, and BSI (p = 0.5). Median NICU blood culture volumes align with recommendations. Night shift collections correlate with lower volumes. Sample volumes don't differ in patients with culture-negative-sepsis, BSI, and sepsis-rule-out, and should not be a justification for longer duration of antibiotics.

Prospective longitudinal analysis of imaging-based spatiotemporal tumor habitats in glioblastoma, IDH-wild type: implication in patient outcome using multiparametric physiologic MRI

BackgroundPhysiologic MRI-based tumor habitat analysis has the potential to predict patient outcomes by identifying the spatiotemporal habitats of glioblastoma. This study aims to prospectively validate the cut-off for tumor progression obtained from tumor habitat analysis based on physiologic MRI in ascertaining time-to-progression (TTP) and the site of progression in glioblastoma patients following concurrent chemoradiotherapy (CCRT).MethodsIn this prospective study (ClinicalTrials.gov ID: NCT02613988), we will recruit patients with IDH-wild type glioblastoma who underwent CCRT and obtained immediate post-operative and three serial post-CCRT MRI scans within a three-month interval, conducted using diffusion-weighted imaging and dynamic susceptibility contrast imaging. Voxels from cerebral blood volume and apparent diffusion coefficient maps will be grouped using k-means clustering into three spatial habitats (hypervascular cellular, hypovascular cellular, and nonviable tissue). The spatiotemporal habitats of the tumor will be evaluated by comparing changes in each habitat between the serial MRI scans (post-operative and post-CCRT #1, #2, and #3). Associations between spatiotemporal habitats and TTP will be analyzed using cox proportional hazard modeling. The site of progression will be matched with spatiotemporal habitats.DiscussionThe perfusion- and diffusion-derived tumor habitat in glioblastoma is expected to stratify TTP and may serve as an early predictor for tumor progression in patients with IDH wild-type glioblastoma.Trial registrationClinicalTrials.gov ID: NCT02613988.

Integrating multi-spectral imaging and Raman spectroscopy for in vivo endoscopic assessment of rat intestinal tract

An integrated system for in vivo multi-spectral imaging (MSI) and Raman spectroscopy was developed to understand the external morphology and internal molecular information of biological tissues. The achieved MSI images were reconstructed by eighteen separated images from 400 nm to 760 nm, whose illumination bands were selected with six tri-channel band filters. Based on the spectral analysis algorithms, the spatial distribution patterns of blood volume, blood oxygen content and tissue scatterer volume fraction were visualized. In vivo Raman spectral measurements were executed by inserting specially designed optical probe into instrumental channel of endoscope. By this way, the molecular composition at selected sampling points could be identified with its fingerprint spectral information under the guidance of molecular imaging modality. Therefore, both structural and compositional features of intestinal membrane could be addressed without labeling and continuously. The achieved results testified that our presented methodology reveals insights not easily extracted from either MSI or Raman spectroscopy individually, which brings the enrichment of biological and chemical meanings for future in vivo studies.

Efficacy and speed of effect after the first dose of aspirin in children with congenital heart disease.

Many paediatric studies report that patients must be established on aspirin therapy for a minimum of 5 days to achieve adequate response. This is not always practical especially in critical settings. Prospective identification of patients that are unresponsive to aspirin sooner could potentially prevent thrombotic events. The aim of this study was to investigate prospectively if the first dose of aspirin is effective in decreasing platelet aggregation, and thromboxane formation and if this can be measured after 2 hours in paediatric cardiology patients. A secondary aim was to identify a cut-off for a novel marker of aspirin responsiveness the maximum amplitude with arachidonic acid, which could potentially dramatically reduce the blood volume required. Third, we aimed to prospectively identify potentially non-responsive patients by spiking a sample of their blood ex vivo with aspirin. The majority (92.3%) of patients were responsive, when measured 2 hours post first dose of aspirin. Non-response or inadequate response (7.7%) can also be identified at 2 hours after taking the first dose of aspirin. Additionally, we have shown a novel way to reduce blood sample volume requirements by measurement of the maximum amplitude with arachidonic acid as a marker of response, particularly for monitoring. These findings of rapid efficacy in the majority of patients offer assurance in a sound, practical way to attending clinicians, patients, and families.

Comparison of the accumulation manner of a macromolecular drug between two mouse tumor models: Study with magnetic resonance imaging and the model macromolecular drug, gadolinium-conjugated dextran

A knowledge of the difference of spatio-temporal behavior of nanomedicine in different type of tumor models is important to develop well-targeted nanomedicine for tumor. In this study, intratumoral accumulation of the model nanomedicine, gadolinium-conjugated dextran (Gd-Dex), was examined with magnetic resonance imaging in two tumor models; mouse sarcoma S180 and radiation-induced mouse fibrosarcoma RIF-1. From time-course of the distribution images, the plasma-to-tumor interstitial tissue transfer constant (Ktrans ) and fractional plasma volume (Vp ) were calculated and mapped. Gd-Dex preferentially distributed to the marginal region of S180 tumors immediately after its injection, and then started to accumulate in some parts of the central region. Ktrans and Vp values were large in the marginal region, while only Ktrans was large in some parts of the central region. In contrast, the distribution of Gd-Dex in RIF-1 tumors was fairly homogeneous, and may have resulted from the homogeneous distributions of Ktrans and Vp . The amounts of Gd-Dex that accumulated in entire tumors in both tumor models correlated with the volume of tumors; however, accumulation in large S180 tumors deviated from the correlation in the early phase. The differences in the manner and pharmacokinetics of nanomedicine among tumor models may affect the accumulation of the medicine.

BP-Diff: a conditional diffusion model for cuffless continuous BP waveform estimation using U-Net.

Continuous monitoring of blood pressure (BP) is crucial for daily healthcare. Although invasive methods provide accurate continuous BP measurements, they are not suitable for routine use. Photoplethysmography (PPG), a non-invasive technique that detects changes in blood volume within the microcirculation using light, shows promise for BP measurement. The primary goal of this study is to develop a novel cuffless method based on PPG for accurately estimating continuous BP.&#xD;Approach. We introduce BP-Diff, an end-to-end method for cuffless continuous BP waveform estimation utilizing a conditional diffusion probability model combined with a U-Net architecture. This approach takes advantage of the stochastic properties of diffusion models and the strong feature representation capabilities of U-Net. It integrates the continuous BP waveform as the initial status and uses the PPG signal and its derivatives as conditions to guide the training and sampling process.&#xD;Main results. BP-Diff was evaluated using both uncalibrated and calibrated schemes. The results indicate that, when uncalibrated, BP-Diff can accurately track BP dynamics, including peak and valley positions, as well as timing. After calibration, BP-Diff achieved highly accurate BP estimations. The mean absolute error (MAE) of the estimated BP waveforms, along with the systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) from the calibrated BP-Diff model, were 2.99 mmHg, 2.6 mmHg, 1.4 mmHg, and 1.44 mmHg, respectively. Consistency tests, including Bland-Altman analysis and Pearson correlation, confirmed its high reliability compared to reference BP. BP-Diff meets the American Association for Medical Instrumentation (AAMI) standards and has achieved a Grade A from the British Hypertension Society (BHS).&#xD;Significance. This study utilizes PPG signals to develop a novel cuffless continuous BP measurement method, demonstrating superiority over existing approaches. The method is suitable for integration into wearable devices, providing a practical solution for continuous BP monitoring in everyday healthcare.

Effect of cephalosporin injection postoperative after cell assisted lipografting in fat survival and improving post burn scar quality

Scars have always been an issue, and the majority of treatments have failed to address them adequately. The biggest obstacle that plastic surgeons still face is finding an effective procedure that works for all skin types in the long run. In a non-invasive way, external volume expansion (EVE) devices use suction to mechanically stretch and stimulate tissues. Different studies have proposed various mechanisms for how stretch releases the skin, including mechanical action on individual cells, inflammation, ischemia, and soluble mediators that promote cell proliferation, adipogenesis, and most crucially, vascular remodeling. Platelet-rich plasma (PRP) is a product made from autologous blood that is concentrated in plasma volume and contains an abundance of platelets, growth factors, and chemo/cytokines. The contents of the alpha and dense granules in PRP have the ability to provide a high concentration of growth factors to the tissues that need them. Autologous fat grafting, initially described by Neuber in 1893 and subsequently improved by Coleman, is a relatively new alternative to scar tissue removal. It is believed that autologous fat grafting improves skin quality by increasing dermal thickness and volume via stimulating the neosynthesis of collagen fibers. It is still unclear what impact autologous fat grafting has on scar tissue, despite its growing popularity in the medical field, and the use of postoperative cephalosporin is very essential for guarding against infection and losing of fat. Critics have cast doubt on its usefulness due to the fact that survival rates can range from 30% to 80% , the infection rate and loss of fat

Exercise training improves cardiovascular fitness in dilated cardiomyopathy caused by truncating titin variants

BackgroundParticipation in regular exercise activities is recommended for patients with chronic heart failure. However, less is known about the effect of exercise in patients with genetic dilated cardiomyopathy (DCM). We...

Clinical and Imaging Features Associated With Fast Infarct Growth During Interhospital Transfers of Patients With Large Vessel Occlusions.

Acute ischemic stroke patients with a large vessel occlusion (LVO) who present to a primary stroke center (PSC) often require transfer to a comprehensive stroke center (CSC) for thrombectomy. Not much is known about specific characteristics at the PSC that are associated with infarct growth during transfer. Gaining more insight into these features could aid future trials with cytoprotective agents targeted at slowing infarct growth. We aimed to identify baseline clinical and imaging characteristics that are associated with fast infarct growth rate (IGR) during interhospital transfer. We included patients from the CT Perfusion to Predict Response to Recanalization in Ischemic Stroke Project, a prospective multicenter study. Patients with an anterior circulation LVO who were transferred from a PSC to a CSC for consideration of thrombectomy were eligible if imaging criteria were fulfilled. A CT perfusion (CTP) needed to be obtained at the PSC followed by an MRI at the CSC, before consideration of thrombectomy. The interhospital IGR was defined as the difference between the infarct volumes on MRI and CTP, divided by the time between the scans. Multivariable logistic regression was used to determine characteristics associated with fast IGR (≥5 mL/h). A total of 183 patients with a median age of 74 years (interquartile range 61-82), of whom 99 (54%) were male and 82 (45%) were fast progressors, were included. At baseline, fast progressors had a higher NIH Stroke Scale score (median 16 vs 13), lower cerebral blood volume index (median 0.80 vs 0.89), more commonly poor collaterals on CT angiography (35% vs 13%), higher hypoperfusion intensity ratios (HIRs) (median 0.51 vs 0.34), and larger core volumes (median 11.80 mL vs 0.00 mL). In multivariable analysis, higher HIR (adjusted odds ratio [aOR] for every 0.10 increase 1.32 [95% CI 1.10-1.59]) and larger core volume (aOR for every 10 mL increase 1.54 [95% CI 1.20-2.11]) remained independently associated with fast IGR. Fast infarct growth during interhospital transfer of acute stroke patients is associated with imaging markers of poor collaterals on baseline imaging. These markers are promising targets for patient selection in cytoprotective trials aimed at reducing interhospital infarct growth.

Chemical Exposomics in Human Plasma by Lipid Removal and Large-Volume Injection Gas Chromatography-High-Resolution Mass Spectrometry.

For comprehensive chemical exposomics in blood, analytical workflows are evolving through advances in sample preparation and instrumental methods. We hypothesized that gas chromatography-high-resolution mass spectrometry (GC-HRMS) workflows could be enhanced by minimizing lipid coextractives, thereby enabling larger injection volumes and lower matrix interference for improved target sensitivity and nontarget molecular discovery. A simple protocol was developed for small plasma volumes (100-200 μL) by using isohexane (H) to extract supernatants of acetonitrile-plasma (A-P). The HA-P method was quantitative for a wide range of hydrophobic multiclass target analytes (i.e., log Kow > 3.0), and the extracts were free of major lipids, thereby enabling robust large-volume injections (LVIs; 25 μL) in long sequences (60-70 h, 70-80 injections) to a GC-Orbitrap HRMS. Without lipid removal, LVI was counterproductive because method sensitivity suffered from the abundant matrix signal, resulting in low ion injection times to the Orbitrap. The median method quantification limit was 0.09 ng/mL (range 0.005-4.83 ng/mL), and good accuracy was shown for a certified reference serum. Applying the method to plasma from a Swedish cohort (n = 32; 100 μL), 51 of 103 target analytes were detected. Simultaneous nontarget analysis resulted in 112 structural annotations (12.8% annotation rate), and Level 1 identification was achieved for 7 of 8 substances in follow-up confirmations. The HA-P method is potentially scalable for application in cohort studies and is also compatible with many liquid-chromatography-based exposomics workflows.

Breath-hold calibrated fMRI mapping of absolute cerebral metabolic rate of oxygen metabolism (CMRO2): An assessment of the accuracy and repeatability in a healthy adult population

Abstract We previously introduced a calibrated fMRI framework that utilises respiratory modulation with only a single gas (CO2) to map the grey matter (GM) cerebral metabolic rate of oxygen consumption (CMRO2). The method decouples and estimates the cerebral blood volume (CBV) and the oxygen extraction fraction (OEF) from a single measure of the maximum BOLD modulation. The method links the two parameters of interest with a model of oxygen diffusion from capillaries to mitochondria which incorporates the cerebral blood flow (CBF). Here, we apply this framework to gas-free breath-hold calibrated fMRI (bhc-fMRI), where simultaneous BOLD and ASL acquisitions are combined with modulation of arterial CO2 through repeated breath-holding. The accuracy and repeatability of the method is assessed in 33 healthy volunteers at rest and during continuous visual stimulation. Average GM OEF estimated from bhc-fMRI was 0.37 ± 0.04, indicating a small bias of 0.04 (with limits of agreement from -0.11 to 0.12) compared to the whole brain OEF of 0.32 ± 0.07 estimated from sagittal sinus using T2 Relaxation Under Spin Tagging (TRUST). The within-session repeatability of GM estimates were moderate to good for OEF, with ICC = 0.75 (0.56–0.87) and good to excellent for CMRO2, with ICC = 0.88 (0.74–0.94). An ROI analysis in the visual cortex found an average CBF increase of 16%, a CMRO2 increase of 12%, and an OEF decrease of 3% during the visual stimulation. The bhc-fMRI measurement of CMRO2 is simple to implement, has comparable accuracy and repeatability to existing gas-based methods, and is sensitive to modulations in metabolism during functional hyperaemia.

The influence of sex, age, and body height on the pulmonary vascular permeability index – a prospective observational study

The pulmonary vascular permeability index (PVPI) is a quotient of the extravascular lung water (EVLW) and the pulmonary blood volume (PBV). In acute respiratory distress syndrome (ARDS), the alveolar-capillary membrane integrity is disrupted. The result is a disproportionate increase of EVLW compared to the PBV and, hence, an increase in PVPI. Thus, PVPI has repetitively been discussed to extend the definition of ARDS. Besides sex, the influence of other anthropometric variables on PVPI has not been studied so far. However, since it is known that EVLW depends on body height and sex, we hypothesize that PVPI depends on anthropometric variables as well. This prospective single-center observational study included 1533 TPTD measurements of 251 non-critically ill patients (50.6% men) undergoing elective neuro-, thoracic, or abdominal surgery at the Munich Clinic Bogenhausen of the Technical University of Munich. Multivariate regressions were used to measure the influence of sex, age, and body height on PVPI. In all patients, PVPI was significantly higher in women (P < 0.001), with 34.4% having a PVPI > 2 compared to 15.9% of men. Mean PVPI significantly decreased with height (P < 0.001) and age (P < 0.001). Multivariate regressions allowed the calculation of mean reference surfaces. The 95th percentile surface for PVPI was > 3 for small and young women and well above 2 for all but tall and elderly men. In patients who underwent (lung reduction) thoracic surgery, the PVPI before and after surgery did not differ significantly (P = 0.531), and post-surgical PVPI did not correlate with the amount of lung resected (P = 0.536). Hence, we conclude that PVPI may be independent of the extent of lung volume reduction. However, PVPI is heavily dependent on sex, age, and body height. Anthropometric variables thus have a significant impact on the likelihood of misclassified abnormal PVPI. This warrants further studies since an increased PVPI, e.g. in the context of an ARDS, may be overlooked if anthropometric variables are not considered. We suggest reference surfaces based on the 95th-percentile corrected for sex, age, and height as a novel approach to normalize PVPI.

Whole Blood Assay with Dual Co-Stimulation for Antigen-Specific Analysis of Host Immunity to Fungal and Viral Pathogens.

Rapid and resource-efficient sample processing, high throughput, and high robustness are critical for effective scientific and clinical application of advanced antigen-specific immunoassays. Traditionally, such immunoassays, especially antigen-specific T-cell analysis by flow cytometry or enzyme-linked immunosorbent spot assays, often rely on the isolation of peripheral blood mononuclear cells. This process is time-consuming, subject to many pre-analytic confounders, and requires large blood volumes. Whole blood-based assays provide a facile alternative with increased pre-analytic robustness and lower blood volume requirements. Furthermore, whole blood-based assays allow for the preservation of inter-cellular interactions that are not captured by assays using isolated cell subsets. Recently, a refined whole blood immunoassay with dual anti-CD28 and anti-CD49d co-stimulation for comprehensive analysis of both antigen-specific T-cell functions and complex intercellular interactions in response to various fungal and viral antigens has been proposed. This protocol provides guidance for the preparation of stimulation tubes, blood stimulation, and downstream sample processing for flow cytometry, cytokine secretion assays, and transcriptional analyses. This includes a validated and functionally equivalent, previously unpublished, low-volume protocol (250 µL) to make flow cytometric and cytokine-based T-cell monitoring more accessible for studies in pediatric patients or preclinical studies in small animals (e.g., mice). Altogether, these protocols provide a versatile toolbox for complex antigen-specific immune analysis in both clinical and translational research settings.

Ice vests extend physiological work time while wearing explosive ordnance disposal protective clothing in hot and humid conditions

BackgroundExplosive ordnance disposal (EOD) technicians may be required to work in hot, humid environments while wearing heavy protective clothing. We investigated the ability of an ice vest to attenuate physiological strain and subsequently extend work tolerance. MethodsEight male participants (24.3 ± 4.1 yr, 51.9 ± 4.6 mL kg−1 min−1) walked (4.5 km h−1) in simulated hot and humid conditions (35 °C; 50% relative humidity). Participants wore either an EOD suit (CON) or EOD and ice vest (IV). Heart rate, core and skin temperature were recorded continuously. ResultsParticipants walked longer in IV compared to CON (8.1 ± 7.4 min, p < .05). Over 90% of trials were terminated based on participants reaching 90% of their maximum heart rate. IV resulted in cooled skin (p < .001) and a physiologically negligible change in core temperature (p < .001). A condition by time interaction was identified for heart rate (p < .001), with a lower rate of rise in the IV condition. ConclusionsThe cardiovascular inefficiency that limited performance was attenuated in the IV condition. The ice vest facilitated heat loss from the periphery; thus, the observed reduction in heart rate may reflect the preservation of central blood volume. The results identify the efficiency of a simple, inexpensive ice vest to assist EOD technicians working in the heat.