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Introduction Impact of blood donor characteristics on quality of packed red blood cell concentrates. Objective To determine the impact of donor factors on the quality of packed red blood cell concentrates. Material and methods The analytical cross sectional study was conducted on 505 whole blood donors after approval by the Institutional Ethics Committee and written informed consent from blood donors. Two mL EDTA sample was collected for pre-donation haemoglobin estimation and all relevant donor details were recorded. Whole blood was collected in 350 mL double blood bags. PRBCs were prepared as per the departmental SOP. Volume of each PRBC was recorded and sample from each bag was taken for estimation of total haemoglobin content and haematocrit. Results Of 505 blood donors, 459 (90.9%) were males and 324 donors (64.2%) were less than 30 years of age. The majority of the donors were repeat donors (61%, n = 308 repeat donors), vegetarians (52.9%, n = 267 vegetarians) and non-smokers (92.7%, n = 468). Mean haemoglobin was found to be significantly higher in males (14.9 vs. 13.3; P ≤ 0.001), donors more than 30 years of age (15 vs. 14.7; P = 0.042), repeat donors (14.9 vs. 14.7), non-vegetarians (15.1 vs. 14.6; P ≤ 0.001) and smokers (15.3 vs. 14.8 g/dL; P = 0.020). PRBC units prepared from male blood donors, repeat donors and non vegetarians had significantly higher mean volume and mean total haemoglobin content. Strong positive correlation was observed between haemoglobin of the blood donor and total haemoglobin content of the PRBC and volume of blood collected. Conclusions Donor characteristics do have effect on total haemoglobin content of packed red blood cells.

Cerebral haemodynamics during the immediate transition period in neonates may differ depending on whether delivery is vaginal or by caesarean section. However, these differences have never been confirmed by near-infrared time-resolved spectroscopy (TRS). Therefore, the purpose of this study was to compare cerebral blood volume (CBV) and cerebral haemoglobin oxygen saturation (ScO2) between healthy term neonates by mode of delivery. Subjects were 31 healthy term neonates who did not require resuscitation. Thirteen neonates were delivered vaginally (VD group) and 18 were delivered by elective caesarean section (CS group). Absolute oxyhaemoglobin, deoxyhaemoglobin, and total haemoglobin concentrations were measured continuously by TRS; oxyHb × 100/totalHb (ScO2) (%) and CBV (mL/100 g brain tissue) were also calculated. Measurements were started as soon as possible after birth, obtained from 1 to 2 min after birth, and continued until 15 min after birth. CBV was significantly higher in the VD group than in the CS group in the 4 min after birth but not thereafter. There were no significant between-group differences in ScO2 and SpO2. These findings indicate that there is a difference in cerebral haemodynamic patterns in the first 4 min after delivery between term neonates by mode of delivery when CBV is monitored by TRS.

International audience; Background and purpose: Better characterization of the thrombus could be useful to determine acute ischaemic stroke (AIS) aetiology and predict response to thrombolysis and endovascular therapy (EVT). To test the hypothesis that susceptibility vessel sign (SVS) on baseline magnetic resonance imaging (MRI) is related to red blood cell (RBC) content of AIS thrombi, the total haemoglobin contents (HbCs) of AIS thrombi retrieved by EVT from patients with or without SVS or two-layered SVS (TLSVS) were compared. Methods: Baseline MRI of 84 anterior AIS patients was reviewed by neuro-radiologists blinded to clinical and biochemical data. Thrombi from these patients were retrieved by EVT and analysed for HbC by quantitative enzyme-linked immunosorbent assay and measurement of haem concentration. Results: Susceptibility vessel sign and TLSVS were respectively observed in 85.7% and 50.0% of cases. The median HbC content was 253 µg/mg thrombus (interquartile range 177–333) and the median haem content was 219 µg/mg thrombus (131–264). Thrombus HbC and haem content were highly correlated with thrombus RBC content determined by flow cytometry (r = 0.94). Thrombi from patients with TLSVS weighed more [31.1 (16.5–68.3) mg vs. 17.7 (11.7–33.3) mg; P = 0.005] and had a higher HbC content [278 (221–331) µg/mg vs. 196 (139–301) µg/mg; P = 0.010] compared to thrombi from patients without TLSVS. There was no difference in thrombus weight or HbC content according to SVS status. Conclusions: Our study shows that TLSVS is significantly associated with a higher thrombus weight and RBC content, as determined by quantitative assays.

Background Total haemoglobin (Hb) concentration in blood belongs to the most requested measurands, and the HiCN method (hemiglobincyanide) is accepted as a reference. Although the reaction principle is clearly characterised, measurement conditions and settings are not consistently defined, some of them influencing the results. An improvement of standardisation is the object. Methods After method optimization, measurement results between different calibration laboratories (CL) were compared with each other and also with results of the National Metrology Institute of Germany (PTB), with target values of certified reference material, within the RELA scheme, and to >1500 results from routine laboratories. Results Overall deviations between three CLs were ≤0.5% (n = 24 samples) in a measurement range of 20 g/L to 300 g/L. A CV of 0.4% was determined in pooled blood (1 year long-term imprecision, 99.0%–101.1% recovery of the mean). For selected measurements (n = 4 samples) the PTB participated without significant differences to three CLs, and no significant differences were observed comparing CLs to certified values of reference materials. The expanded measurement uncertainty (probability 95%) was estimated as 1.1%. Conclusions A reference measuring system, comprising measuring instruments and other devices, including reagents and supply, to generate reference measurement values for total Hb concentration of high accuracy and low measurement uncertainty is presented. Measurement parameters are investigated and defined. The reference measuring system is ready to offer service to EQA providers and to the IVD industry for certifying control materials or calibrators.

Cerebral blood volume (CBV) has been shown to be a robust and important physiological parameter for quantitative interpretation of functional (f)MRI, capable of delivering highly localized mapping of neural activity. Indeed, with recent advances in ultra-high-field ( ≥ 7T) MRI hardware and associated sequence libraries, it has become possible to capture non-invasive CBV weighted fMRI signals across cortical layers. One of the most widely used approaches to achieve this (in humans) is through vascular-space-occupancy (VASO) fMRI. Unfortunately, the exact contrast mechanisms of layer-dependent VASO fMRI have not been validated for human fMRI and thus interpretation of such data is confounded. Here we validate the signal source of layer-dependent SS-SI VASO fMRI using multi-modal imaging in a rat model in response to neuronal activation (somatosensory cortex) and respiratory challenge (hypercapnia). In particular VASO derived CBV measures are directly compared to concurrent measures of total haemoglobin changes from high resolution intrinsic optical imaging spectroscopy (OIS). Quantified cortical layer profiling is demonstrated to be in agreement between VASO and contrast enhanced fMRI (using monocrystalline iron oxide nanoparticles, MION). Responses show high spatial localisation to layers of cortical processing independent of confounding large draining veins which can hamper BOLD fMRI studies, (depending on slice positioning). Thus, a cross species comparison is enabled using VASO as a common measure. We find increased VASO based CBV reactivity (3.1 ± 1.2 fold increase) in humans compared to rats. Together, our findings confirm that the VASO contrast is indeed a reliable estimate of layer-specific CBV changes. This validation study increases the neuronal interpretability of human layer-dependent VASO fMRI as an appropriate method in neuroscience application studies, in which the presence of large draining intracortical and pial veins limits neuroscientific inference with BOLD fMRI.

NEW FINDINGS: What is the central question of this study? Is it possible to modify the CO-rebreathing method to acquire reliable measurements of haemoglobin mass in ventilated patients? What is the main finding and its importance? A 'single breath' of carbon monoxide with a subsequent 30 sec breath hold provides almost as exact a measure of haemoglobin mass as the established optimized CO-rebreathing method when applied to healthy subjects. The modified method has now to be checked in ventilated patients before it can be used to quantify the contributions of blood loss and of dilution to the severity of anaemia. ABSTRACT: Anaemia is defined by the concentration of haemoglobin ([Hb]). However, this value is dependent upon both the total circulating haemoglobin mass (tHb-mass) and the plasma volume (PV) - neither of which are routinely measured. Carbon monoxide- (CO) rebreathing methods have been successfully used to determine both PV and tHb-mass in various populations. However, these methods are not yet suitable for ventilated patients. This study aimed to modify the CO-rebreathing procedure such that a single inhalation of a CO bolus would enable its use in ventilated patients. Eleven healthy volunteers performed four CO-rebreathing tests in a randomized order, inhaling an identical CO-volume. In two tests, CO was rebreathed for 2min (oCOR), and in the other two tests, a single inhalation of a CO bolus was conducted with a subsequent breath hold of 15sec (Procnew 15sec) or 30sec (Procnew 30sec). Subsequently, the CO volume in the exhaled air was continuously determined for 20 min. The amount of CO exhaled after 7min (after 20min) for oCOR was 3.1 ±0.3ml (5.9 ±1.1ml); for Procnew 15sec, 8.7 ±3.6ml (12.0 ±4.4ml); and for Procnew 30sec, 5.1 ±2.0ml (8.4 ±2.6ml)). tHb-mass determined by oCOR was 843 ±293g, from Procnew 15sec 821 ±288g (difference: p

Spectroscopic optical coherence tomography (sOCT) has emerged as a new possibility for non-invasive quantification of total haemoglobin concentrations [tHb]. Recently, we demonstrated that [tHb] measured in ex-vivo human whole-blood with a conventional sOCT system achieves a precision of 9.10 g/dL with a bias of 1.50 g/dL. This precision improved by acquiring data with a combination of focus tracking and zero-delay acquisition (FZA) that compensated for experimental limitations, increasing to 3.80 g/dL with a bias of 1.50 g/dL. Nevertheless, sOCT precision should improve at least to $$\sim 2$$ ∼ 2 g/dL to be clinically relevant. Therefore, sOCT-based [tHb] determinations require the development of new analysis methods that reduce the variability of [tHb] estimations. In this work, we aim to increase sOCT precision by retrieving the [tHb] content from a numerical optimisation of the optical density (OD), while considering the blood absorption flattening effect. The OD-based approach simplifies previous two-step Lambert–Beer fitting approaches to a single step, thereby reducing errors during the fitting procedure. We validated our model with ex-vivo [tHb] measurements on flowing whole-blood samples in the clinical range (7–23 g/dL). Our results show that, with the new model, conventional sOCT can determine [tHb] with a precision of 3.09 g/dL and a bias of 0.86 g/dL compared to a commercial blood analyser. We present further precision improvement by combining the OD methodology with FZA, leading to a precision of 2.08 g/dL with a bias of 0.46 g/dL.

Cerebral blood volume (CBV) has been shown to be a robust and important physiological parameter for quantitative interpretation of functional (f)MRI, capable of delivering highly localized mapping of neural activity. Indeed, with recent advances in ultra-high-field (>=7T) MRI hardware and associated sequence libraries, it has become possible to capture non-invasive CBV weighted fMRI signals across cortical layers. One of the most widely used approaches to achieve this (in humans) is through vascular-space-occupancy (VASO) fMRI. Unfortunately, the exact contrast mechanisms of layer-dependent VASO fMRI have not been validated and thus interpretation of such data is confounded. Here we cross-validate layer-dependent VASO fMRI contrast in a preclinical rat model using well established (but invasive) imaging methods in response to neuronal activation (somatosensory cortex) and respiratory challenge (hypercapnia). In particular VASO derived CBV measures are directly compared to concurrent measures of total haemoglobin changes from high resolution intrinsic optical imaging spectroscopy (OIS). Through direct comparison of response magnitude, across time, negligible changes in hematocrit ratio during activation (neuronal or vascular) are inferred. Quantified cortical layer profiling is demonstrated and in agreement between both VASO and contrast enhanced fMRI (using monocrystalline iron oxide nanoparticles, MION). Responses show high spatial localisation to layers of cortical excitatory and inhibitory processing independent of confounding large draining veins which hamper BOLD fMRI studies. While we find increased VASO based CBV reactivity (3.1 ± 1.2 fold increase) in humans compared to rats it is demonstrated that this reflects differences in stimulus design rather than confounds of the VASO signal source. Together, our findings confirm that the VASO contrast is indeed a reliable estimate of layer-specific CBV changes. This validation study increases the neuronal interpretability of human layer-dependent fMRI results and should supersede BOLD fMRI as the method of choice in neuroscience application studies.HighlightsOur goal is to validate layer-specific VASO fMRI with gold standard methodsLayer-specific VASO sequences are implemented for 7T imaging in humans and ratsComparisons of VASO, optical imaging, and MION confirm the expected contrast originSomatosensory stimulation in humans and rats reveal the same layer-fMRI signaturesWe confirm that VASO is a valid measure to estimate layer-specific neural activityGraphical abstract

IntroductionPhotoacoustic imaging (PAI) enables the detection of blood haemoglobin (HB) concentration and oxygenation (SO2) with high contrast and resolution. To date, the relationship between photoacoustically determined total Haemoglobin (THbMSOT) and oxygen saturation (SO2) biomarkers and the underlying biochemical blood parameters has yet to be established. We sought to explore these relationships in a species-specific manner.MethodsExperiments were performed in vitro using tissue-mimicking agar phantoms. Blood was extracted from mouse, rat, human and naked mole-rat (Heterocephalus glaber), anticoagulated in EDTA and measured within 48 hours. THbMSOT and SO2MSOT were measured using a commercial photoacoustic tomography system (InVision 128, iThera Medical GmBH). Biochemical blood parameters such as haemoglobin concentration (HB, g/dL), haematocrit (HCT, %) and red blood cell count (RBC, μL-1) were assessed using a haematology analyser (Mythic 18 Vet, Woodley Equipment).ResultsA significant correlation was observed between THbMSOT and biochemical HB, HCT and RBC in mouse and rat blood. Moreover, PAI accurately recapitulated inter-species variations in HB and HCT between mouse and rat blood and resolved differences in the oxygen dissociation curves between human, mouse and rat. With these validation data in hand, we applied PAI to studies of blood obtained from naked mole-rats and could confirm the high oxygen affinity of this species in comparison to other rodents of similar size.ConclusionIn summary, our results demonstrate the high sensitivity of photoacoustically determined biomarkers towards species-specific variations in vitro.

The aim of the present study is the modelling of the total haemoglobin mass responses in altitude environment with the dose-response model in elite endurance athletes and comparison different existing approaches in the quantification of hypoxic dose.Data from seven healthy elite endurance athletes specialised in middle distance speed skating participated in the study: six males (24±1.8 years, 182 ±0.3 cm, 84 ±1.5 kg, BMI 23.2±0.6 kg/m2, 59.3±1.5 ml/kg/min) and one female (21 years, 164 cm, 56 kg, BMI 17.1 kg/m2, 59.9 ml/kg/min). Data were collected during a 3-month training period which included two training camps (14 +14 days) at sea level and two training camps (21+21 days) at altitude of 1224 m and 1850 m above sea level. Total haemoglobin mass (tHb-mass) were measured before the start of the season (baseline) and before and after each training camp (seven measurements) using an optimized CO-rebreathing method, training loads and oxygen saturation at altitude were measured and hypoxic dose were calculated.Mean total haemoglobin mass for the male group at the base line were 1067±83 g, before the training camp 1 were 1095±82 g, after TC1 1113±105 g, before the training camp 2 (TC2) 1107±88 g, after TC2 1138±104 g. For the female athlete at the base line were 570 g, after TC1 564 g, after TC2 582 g.The increase of tHb-mass after TC2 were 3,25% and were significant (pThe relationship between hypoxic dose and haematological response was analysed with a non-linear model. The magnitude of the increase of the total haemoglobin mass were investigated using simulation procedures based upon individual responses to the hypoxic dose. We introduced a measurement error to the list square method as a way of avoiding overfitting problem. Dose-response mathematical model between hypoxic dose and total haemoglobin mass was developed. Modelled total haemoglobin mass was within measurement error range. This model is suitable for the computer simulations. The individual response to hypoxic dose due to model data was different. Maximal values in total haemoglobin mass that can be achieved by male athletes according to the model was 1321.9 ± 32 g. The model predicted that (τ) erythrocyte life span is 73.8 ± 9.0 days. Moreover, highest value of individual tHb-mass increase after returning to the sea level according to the model was16.3 ±0.7 days.The model developed in the current study describes the time course of total haemoglobin mass during altitude exposure and post-altitude decline in elite speed skaters.

Background Anemia is common in liver cirrhosis. This generally infers a fall in total hemoglobin mass (tHb‐mass). However, hemoglobin concentration ([Hb]) may fall due to an expansion in plasma volume (PV). The “optimized carbon monoxide rebreathing method” (oCOR) measures tHb‐mass directly and PV (indirectly using hematocrit). It relies upon carboxyhemoglobin (COHb) distribution throughout the entire circulation. In healthy subjects, such distribution is complete within 6–8 min. Given the altered circulatory dynamics in cirrhosis, we sought in this pilot study, to assess whether this was true in cirrhosis. The primary aim was to ascertain if the standard timings for the oCOR were applicable to patients with chronic liver disease and cirrhosis. The secondary aim was to explore the applicability of standard CO dosing methodologies to this patient population. Methods Sixteen patients with chronic liver parenchymal disease were studied. However, tHb‐mass was determined using the standard oCOR technique before elective paracentesis. Three subjects had an inadequate COHb% rise. In the remaining 13 (11 male), mean ± standard deviation (SD) age was 52 ± 13.8 years, body mass 79.1 ± 11.4 kg, height 175 ± 6.8 cm. To these, mean ± SD dose of carbon monoxide (CO) gas administered was 0.73 ± 0.13 ml/kg COHb values at baseline, 6 and 8 min (and “7‐min value”) were compared to those at 10, 12, 15 and 20 min after CO rebreathing. Results The “7‐min value” for median COHb% (IQR) of 6.30% (6.21%–7.47%) did not differ significantly from those at subsequent time points (8 min: 6.30% (6.21%–7.47%), 10 min: 6.33% (6.00%–7.50%), 12 min: 6.33% (5.90%–7.40%), 15 min: 6.37% (5.80%–7.33%), 20 min: 6.27% (5.70%–7.20%)). Mean difference in calculated tHb‐mass between minute 7 and minute 20 was only 4.1 g, or 0.6%, p = .68. No subjects reported any adverse effects. Conclusions The oCOR method can be safely used to measure tHb‐mass in patients with chronic liver disease and ascites, without adjustment of blood sample timings. Further work might refine and validate appropriate dosing regimens., Anaemia is common in liver cirrhosis. This generally infers a fall in total haemoglobin mass (tHb‐mass). The “optimized carbon monoxide rebreathing method” (oCOR) measures tHb‐mass and PV. It relies upon carboxyhaemoglobin (COHb) distribution throughout the entire circulation. In healthy subjects, such distribution is complete within 6–8 min. Given the altered circulatory dynamics in cirrhosis, we sought to assess whether this was true in cirrhosis. The “7‐min value” for median COHb% (IQR) of 6.30% (6.21%–7.47%) did not differ significantly from those at subsequent time points. Therefore, the oCOR method can be safely used to measure tHb‐mass in patients with chronic liver disease and ascites, without adjustment of blood sample timings.

Blood flow changes in response to exercise have been attributed, among other factors, to the effect of vasodilators factors on the microvasculature, suggesting a close relationship between small blood vessels and conducting arteries. The main purpose of this study was to determine the relationship between the changes in near infrared spectroscopy (NIRS)-derived total haemoglobin ([tHb]) and muscle oxygen saturation (SmO

NEW FINDINGS What is the central question of this study? Does ischaemic preconditioning (IPC) influence central and peripheral fatiguing mechanisms during sustained maximal isometric exercise? What is the main finding and its importance? Voluntary activation and pre- to postexercise reductions in resting twitch torque values were unchanged by IPC. However, an effect on tissue oxygenation was observed within the IPC trials, where greater concentrations of deoxyhaemoglobin were recorded with concurrent upward trends of total haemoglobin concentrations. Using a direct assessment of neural drive, we found that IPC had no influence on either central or peripheral fatiguing pathways after maximal isometric exercise. ABSTRACT Ischaemic preconditioning (IPC) is thought to inhibit neural feedback from metabolically sensitive muscle afferents during exercise. It was hypothesized that IPC could affect mechanisms associated with centrally mediated fatigue after a maximally fatiguing protocol. Eleven resistance-trained men completed three 2 min maximal voluntary contractions (MVCs) via an isometric leg extension preceded by treatments of IPC (three bouts of 5 min bilateral leg occlusions at 220 mmHg), SHAM (three bouts of 5 min at 20 mmHg) or CON (30 min passive rest). Femoral nerve stimulation was used to explore central and peripheral fatigue pathways. These pathways were profiled at baseline (BL), before the 2 min MVC (Pre) and 10 s afterwards (Post). Tissue oxygenation was measured throughout the 2 min MVCs via near-infrared spectroscopy. The Pre to Post MVC (-71 ± 56 Nm; d = 1.33 ± 0.51, P

The increment in a patient's haemoglobin level is based upon the haemoglobin content of the transfused RBC units. The total haemoglobin present in the blood bags can vary because of the blood donor, processing method, volume and type of bag used. The study is done to analyse the factors causing variation of haemoglobin content in RBC units.A total of 260 RBC units were tested for the haemoglobin content and analysed with the donor variables (age, gender, weightcapillary haemoglobin). The blood bags were then separated into two groups based on the donor capillary haemoglobin (normal 12.5-15.0 g/dL vs high 15.1-18.0 g/dL), volume (350 vs 450 mL), processing method (Platelet rich plasma vs buffy coat) and further analysis was carried out.The mean haemoglobin content was 54.7 g ranging from 34.2-80 g per unit. The factors which significantly influenced (p0.0001) were capillary haemoglobin, gender and weight of donor, volume of blood collected and the processing method. There was a significant difference (p0.0001) in haemoglobin content between the two groups in all the three categories (capillary haemoglobin, volume and processing method). Regression analysis showed all three of them contributed to 80 % variability of haemoglobin content in the RBC unit.The marked variation of haemoglobin content in our study revealed that there is a need for standardizing RBC unit. Labelling of units with haemoglobin content and transfusion based on it will result in better patient care.

Background Cardiopulmonary exercise testing (CPET) measures peak exertional oxygen consumption ( V ˙ O 2 peak ) and that at the anaerobic threshold ( V ˙ O 2 at AT, i.e. the point at which anaerobic metabolism contributes substantially to overall metabolism). Lower values are associated with excess postoperative morbidity and mortality. A reduced haemoglobin concentration ([Hb]) results from a reduction in total haemoglobin mass (tHb-mass) or an increase in plasma volume. Thus, tHb-mass might be a more useful measure of oxygen-carrying capacity and might correlate better with CPET-derived fitness measures in preoperative patients than does circulating [Hb]. Methods Before major elective surgery, CPET was performed, and both tHb-mass (optimized carbon monoxide rebreathing method) and circulating [Hb] were determined. Results In 42 patients (83% male), [Hb] was unrelated to V ˙ O 2 at AT and V ˙ O 2 peak (r=0.02, P=0.89 and r=0.04, P=0.80, respectively) and explained none of the variance in either measure. In contrast, tHb-mass was related to both (r=0.661, P

Background Non-invasive monitoring of cerebral tissue oxygen saturation (rcSO2) during transition is of growing interest. Different near-infrared spectroscopy (NIRS) techniques have been developed to measure rcSO2. We compared rcSO2 values during the immediate transition in preterm neonates measured with frequency-domain NIRS (FD-NIRS) with those measured with continuous-wave NIRS (CW-NIRS) devices in prospective observational studies. Methods We compared rcSO2 values measured with an FD-NIRS device during the first 15 min after birth in neonates with a gestational age ≥ 30 weeks but 2 measurements, with fixed effects for time (non-linear), device, respiratory support and the interaction of device and respiratory support with time. Additionally, parameters such as total haemoglobin concentration and oxygenated and deoxygenated haemoglobin concentrations measured by FD-NIRS were analysed. Results Thirty-eight FD-NIRS measurements were compared with 58 CW-NIRS measurements. The FD-NIRS rcSO2 values were consistently higher than the CW-NIRS rcSO2 values in the first 12 min, irrespective of respiratory support. After adjustment for respiratory support, the time-dependent trend in rcSO2 differed significantly between techniques (p Conclusion As cerebral saturation measured with the FD-NIRS device differed significantly from that measured with the CW-NIRS device, differences in absolute values need to be interpreted with care. Although FD-NIRS devices have technical advantages over CW-NIRS devices, FD-NIRS devices may overestimate true cerebral oxygenation and their benefits might not outweigh the usability of the more clinically viable CW-NIRS devices.

The non-invasive quantification of total haemoglobin concentrations [tHb] is highly desired for the assessment of haematologic disorders in vulnerable patient groups, but invasive blood sampling is still the gold standard in current clinical practice. This work demonstrates the potential of visible-light spectroscopic optical coherence tomography (sOCT) for quantifying the [tHb] in human whole blood. To accurately quantify the [tHb] from the substantial optical attenuation by blood in the visible wavelength range, we used a combination of zero-delay acquisition and focus tracking that ensures optimal system sensitivity at any depth inside the sample. Subsequently, we developed an analysis model to adequately correct for the high scattering contribution by red blood cells to the sOCT signal. We validate our method and compare it to conventional sOCT (without focus tracking and zero-delay acquisition) through ex-vivo measurements on flowing human whole blood, with [tHb] values in the clinical range of 7–23 g/dL. For our method with optimized sensitivity, the measured and expected values correlate well (Pearson correlation coefficient = 0.89, p

BACKGROUND Reference intervals for arterial and venous umbilical cord blood gas (UCBG) parameters are scarce, are mainly focused on pH, pO2, pCO2 and base deficit, and are usually assessed using parametric tests, despite a generally skewed data distribution. Here, the purpose is to determine reference percentiles for nine parameters of concomitant arterial and venous UCBG (CAV-UCBG) from neonates at birth, using nonparametric tests. METHODS Results of CAV-UCBG, assayed over a 4.5-year period, were extracted from a hospital laboratory database for pH, pCO2, pO2, oxygen saturation, concentration of total oxygen, total carbon dioxide, hydrogen carbonate, total haemoglobin, and acid-base excess. Exclusion criteria were: a venous-arterial pH difference

The total haemoglobin (Hb) concentration in blood is one of the most frequently measured analytes in clinical medicine because of its significance for evaluating the health state of a human. The spectrophotometric cyanmethaemoglobin (HiCN) method is the internationally accepted conventional reference method to determine this biomarker. It is frequently used in clinical routine diagnostics but is not traceable to the International System of Units and thus does not meet highest metrological demands. A further critical issue is the toxicity of the necessary potassium cyanide. Different methods to solve these problems are reported here. They all were validated against the HiCN method in an interlaboratory comparison by measuring the total Hb concentration present in the certified reference material JCCRM 912-2M. Methods considered were the spectrophotometric alkaline haematin detergent (AHD) method as well as several isotope dilution (ID)-based approaches. The latter include inductively coupled plasma mass spectrometry (ICP-MS), species-specific (SS) ICP-MS, organic MS and Raman spectrometry. Graphical abstract ᅟ.

Acute exercise-induced improvements in cognitive function are accompanied by increased (cerebral) blood flow and increased brain-derived neurotrophic factor (BDNF) levels. Acute cocoa flavanol (CF) intake may improve cognitive function, cerebral blood flow (in humans), and BNDF levels (in animals). This study investigated (i) the effect of CF intake in combination with exercise on cognitive function and (ii) cerebral hemodynamics and BDNF in response to CF intake and exercise. Twelve healthy men participated in this randomized, double-blind, crossover study. Participants performed a cognitive task (CT) at 100 min after acute 903-mg CF or placebo (PL) intake, followed by a 30-min time-trial. Immediately after this exercise, the same CT was performed. Prefrontal near-infrared spectroscopy was applied during CT and exercise to measure changes in oxygenated (ΔHbO2), deoxygenated (ΔHHb), and total haemoglobin (ΔHbtot) and blood samples were drawn and analyzed for BDNF. Reaction time was faster postexercise, but was not influenced by CF. ΔHbO2 during the resting CT was increased by CF, compared with PL. ΔHbO2, ΔHHb, and ΔHbtot increased in response to exercise without any effect of CF. During the postexercise cognitive task, there were no hemodynamic differences between CF or PL. Serum BDNF was increased by exercise, but was not influenced by CF. In conclusion, at rest, CF intake increased cerebral oxygenation, but not BDNF concentrations, and no impact on executive function was detected. This beneficial effect of CF on cerebral oxygenation at rest was overruled by the strong exercise-induced increases in cerebral perfusion and oxygenation.

Haemoglobin variants are inherited disorders of haemoglobin, it is one of the commonest single gene disorder affecting millions of people all over the world, including India. Haemoglobinopathies cause major genetic and public health problems. So, the present study is carried out to find carriers among the healthy individuals to prevent silent transmission of the disorder among the population. Materials and Method: In this study a total of 200 subjects were included amongst the medical students, nurses and nursing students of Silchar Medical College and Hospital for analysis of haemoglobin variants. The study was performed by Horizontal electrophoresis Pherotank by using cellulose acetate membrane and Tris buffer at pH 8.5. Results: Out of 200 subjects studied, 49 subjects had abnormal haemoglobin type. Hb E trait was the most predominant with 31(15.5%) incidence, followed by 9(4.50 %) of HbE/thalassemia, and 6 (3 %) subjects were also found to have HbE disease. It was also seen that thalassemia trait was found in 3 (1.50%) subjects. It was also found that out of total haemoglobin variants 24(48.97%) subjects of HbE trait were anaemic and 7(14.20%) were non-anaemic . 5(10.20%) subjects of HbE disease were anaemic and 1 subject was found to be non- anaemic.

In this paper we present a Time Resolved Near Infrared device for bed-side neuromonitoring of ischemic stroke patients. This system features three wavelengths allowing a better and robust retrieval of the absolute values of oxy and deoxyhaemoglobin. The device has been fully characterized following the guidelines of the MEDPHOT and BIP protocols, developed under NEUROPt project. Time Resolved spectroscopy is a promising technology that can provide reproducible results in terms of absorption and scattering coefficients. This portable and non-invasive system has been proven suitable for operation in clinical settings. Data were collected from a cohort of 47 ischemic stroke patients and, according to their cerebral impairment, compared with normal values obtained from a group of 35 healthy subjects. Significant differences in haemoglobin species concentration and saturation were found between healthy and ischemic stroke patients. In the ischemic area of both recanalized and non-recanalized ischemic stroke patients, deoxy-haemoglobin and total haemoglobin values are higher than in controls, while tissue oxygen saturation values are lower only in recanalized patients. © 2019 SPIE.

In a classical dichotic listening paradigm, besides auditory brain asymmetry, cognitive functions such as attention and conflict resolution play a major role. The aim of this study is to reveal the possible haemodynamic mechanisms of higher attentional performance in prefrontal cortex during dichotic listening test. Twenty-six healthy participants underwent a dichotic listening task in three sessions; non-forced attention, attention focused to right ear, and attention focused to left ear. In each session, haemodynamic activity of prefrontal brain area was recorded using functional near-infrared spectroscopy (fNIRS). Effects of focused attention and performance level of the task on oxy-, deoxy-, and total haemoglobin levels were investigated. Oxy- and total haemoglobin levels in right prefrontal regions during forced-right and forced-left sessions were significantly higher than levels of the non-forced session. This might be an indicator of inhibition and orienting attentional functions of right inferior frontal gyrus. High performers had significantly higher deoxyhaemoglobin levels in the forced-left session compared to the non-forced session, while low performers' deoxyhaemoglobin levels did not differ among these sessions. Observing this difference only in the forced-left session but not in the forced-right session might suggest conflict resolution in top-down and bottom-up processes during the forced-left session for right-handed participants.

Interrelationships between physiological changes (Δ) in erythropoietin (EPO), plasma volume (PV), haemoglobin concentration ([Hb]), and total haemoglobin mass (tHb-mass) were examined in cyclists who trained in different altitudes. Regardless of differences in pattern of changes observed in three training locations, ΔEPO was correlated positively with ΔPV, negatively with Δ[Hb], and trivially with ΔtHb-mass. Δ[Hb] was negatively correlated with ΔPV. In the pooled data the Spearman's rank correlation coefficients were as follows: r = 0.783, P 0.001; r = -0.704, P 0.001; r = 0.136, P 0.05; r = -0.813, P 0.001, respectively. The obtained results have shown that EPO does not only regulate [Hb] by erythropoiesis stimulation but also by PV modulation, which probably aims at keeping proper level of arterial oxygen content for oxygen delivery to tissues.

Near-infrared spectroscopy (NIRS) provides a non-invasive, non-ionizing means to monitor total haemoglobin concentration and oxygen saturation in the living tissue allowing monitoring oxygen sufficiency. Main applications of NIRS are in the study of the transport of the oxygen to the muscles, the cellular metabolism and the cerebral haemodynamics.

Eating utensils are usually used from early childhood and thereafter throughout life; therefore, clarification of the effect of use of eating utensils on the brain would be an important topic. Using functional near infrared spectroscopy, we attempted to compare patterns of cortical activation generated during the use of three eating utensils. Twenty healthy normal subjects were recruited. The experimental tasks included transfer of black beans using a fork, wooden chopsticks and stainless steel chopsticks. We measured values of oxyhaemoglobin (HbO) and total haemoglobin (HbT) in five regions of interest: the prefrontal cortex (PFC), frontal eye field (FEF), premotor cortex (PMC), supplementary motor area and primary sensorimotor cortex (SM1). HbO values in all five regions of interest were significantly higher during use of stainless steel chopsticks, compared with use of wooden chopsticks and a fork ( p < 0.05). Regarding the analysis in each region of interest, higher activation was observed in the PFC and FEF during use of wooden chopsticks and stainless steel chopsticks than during use of a fork and wooden chopsticks, respectively, in terms of HbO and HbT ( p < 0.05). HbO value during use of stainless steel chopsticks was higher than that during use of a fork in the PMC and SM1 ( p < 0.05). Use of stainless steel chopsticks involves greater recruitment of neuronal activation in the cerebral cortex, compared with use of wooden chopsticks or a fork.

Summary We aimed at evaluating the effect of isometric muscle contraction on intramuscular water movement at different exercise intensities. Seven men performed 1-min isometric ankle dorsiflexion (20% and 50% maximal voluntary contractions [MVCs]) with a non-magnetic custom-made dynamometer, inside a magnetic resonance (MR) device. Axial diffusion-weighted images were obtained before, during and at 1–20 min (1-min interval) after the exercise to calculate the apparent diffusion coefficient (ADC) of the tibialis anterior. Under the same exercise condition, the concentration change of total haemoglobin (Hb) and myoglobin (Mb) (total Hb/Mb) within the tibialis anterior was assessed by performing near-infrared spectroscopy before, during and after the exercise outside the MR device. The 20% MVC exercise significantly increased the ADC only at 1 min postexercise (P

The study aimed to evaluate the clinical feasibility of hybrid ultrasound/multispectral optoacoustic tomography (MSOT) for assessing microvascular dysfunction in systemic sclerosis (SSc). A handheld US/MSOT imaging system was applied for imaging patients diagnosed with SSc (n = 7) and healthy volunteers (n = 8). Semiquantitative MSOT values for deoxygenated (HbR), oxygenated (HbO(2)) and total haemoglobin (HbT) were analysed for subcutaneous finger tissue of both hands (8 fingers per subject, 120 fingers in total) and used to assess disease activity (progressive vs stable). Grouped data were compared by one-way nested analysis of variance, Tukey post-hoc test as well as student's t test were used for statistical analysis.Subcutaneous finger tissue of patients with SSc provided significantly lower MSOT values for HbO(2) (26.16 +/- 0.71 vs 38.2 +/- 1.54, P =.023) and HbT (55.92 +/- 1.62 vs 72.46 +/- 1.90, P =.018) compared to healthy volunteers. Patients with progressive SSc had significantly lower MSOT values compared to patients with stable disease and healthy volunteers.This pilot study shows the feasibility of MSOT imaging to resolve microvascular dysfunction in SSc as a marker of disease activity. By providing biological tissue properties not revealed by other imaging modalities, MSOT might help to grade SSc non-invasively and monitor early therapy response.

[Purpose] The purpose of this study was to investigate whether the occurrence of cardiac-locomotor synchronization (CLS) improves lower leg muscle blood perfusion during walking. [Subjects and Methods] Eleven healthy men were studied while performing two treadmill protocols. The CLS protocol involved subjects walking at the frequency of their heart rate (HR) to induce CLS. The free protocol (reference) involved subjects walking at a self-selected cadence. The treadmill load was identical in the two protocols. Electrocardiographic signals for HR, foot switch signals for step rate and near-infrared spectroscopy (NIRS) signals for total haemoglobin (total Hb) in the lower leg muscles were measured continuously for 10 min after HR reached a steady state. [Results] The mean HR and mean step rate did not differ between the CLS and free protocols. However, total Hb was significantly higher in the CLS protocol than in the free protocol. The rate of increase in total Hb positively correlated with the strength of CLS. [Conclusion] These results suggest that the occurrence of CLS enhances lower leg muscle blood perfusion by increasing the strength of CLS during walking.

Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2 for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔHbO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2), reduced (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔHHb) and total haemoglobin (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔtHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions. A reflectance PPG sensor was attached on the left forearm of nineteen (n = 19) volunteers, along with a reference NIRS sensor positioned on the same forearm, above the left brachioradialis. The investigation protocol consisted of seven intermittent and pressure-increasing vascular occlusions. Relative changes in haemoglobin concentrations were obtained by applying the modified Beer–Lambert law to PPG signals, while oxygenation changes were estimated by the difference between red and infrared attenuations of DC PPGs (A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{Ox}$$\end{document}Ox = \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔA\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{IR}$$\end{document}IR − \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔA\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_R$$\end{document}R) and by the conventional SpO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2. The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔHbO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_2$$\end{document}2, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔHHb, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta$$\end{document}ΔtHb from the PPG signals indicated significant changes in perfusion induced by either partial and complete occlusions (p

Background: Carbon monoxide (CO) poisoning is an important public health issue around the world. Research indicates that many factors may be related to the rate of CO uptake and elimination in the human body. However, some factors related to CO uptake and elimination are considered controversial. Relatively little attention has been devoted to review and synthesis of factors affecting CO uptake and elimination. Purpose: This paper provides a critical scoping review of the factors and divides them into four aspects, including environmental, demographic, physiological and treatment factors. Methods: We searched the scientific databases for research that has proposed a mathematical equation as a synthesis of quantities related to CO poisoning, CO elimination, CO uptake, CO half-life, CO uptake and elimination and their relationships. After excluding the studies that did not meet the study criteria, there were 39 studies included in the review and the search was completed before 16 December 2019. Results and conclusion: This review discusses most of the factors that impact the rate of CO uptake and elimination. Several factors may be related to CO uptake and elimination, such as CO concentration, the duration of exposure to CO, age, sex, exercise, minute ventilation, alveolar ventilation, total haemoglobin mass and different treatments for CO poisoning. Although some potential factors were not included in the review, the findings are useful by presenting an overview for discussing factors affecting CO uptake and elimination and provide a starting point for further study regarding strategies for CO poisoning and the environmental standard of CO.

A new Radiometer™ hemoximeter (ABL-80) has recently become available to measure carboxyhaemoglobin concentration for the optimized CO-rebreathing method (oCOR-method). Within the English Institute of Sport (EIS), hemoximeters are used in three different laboratories; therefore, precision and agreement of total haemoglobin mass (tHbmass) determination across sites is essential, and comparison to the previous model OSM-3 is desirable. Six male and one female (age 30 ± 6 years, body mass 78.1 ± 10.6 kg) undertook the oCOR-method. Venous blood (~2 ml) was sampled immediately before and at 7 min during the oCOR-method; with seven replicates from each time point simultaneously analysed on five different Radiometer™ hemoximeters [OSM-3(1), OSM-3(2), ABL-80(1), ABL-80(2) and ABL-80(3)]. There were no differences (p > 0.05) between Δ%HbCO or mean tHbmass analysed with five different hemoximeters (OSM-3(1): 886 ± 167 g; OSM-3(2): 896 ± 160 g: ABL-80(1): 904 ± 157 g; ABL-80(2): 906 ± 163 g: ABL-80(3): 906 ± 162 g). However, the Bland-Altman plot revealed that there was closer agreement between ABL-80 machines for tHbmass than for the OSM-3. The variance (i.e. % error) across replicate samples decreased as the number of samples increased, with the error derived from the 'worse-case' scenario (single samples) being 1.2 to 1.6 fold greater in the OSM-3 than the ABL-80. Although there were no differences in the average tHbmass measured with five different hemoximeters, the new ABL-80 were in better agreement with each other compared to the old OSM-3. Previously, five replicates were required to achieve a low error using the OSM-3; however, three replicates are sufficient with the ABL-80 model to produce an error of ≤ 1% in tHbmass.

Background: The haemoglobin content and red blood cells counts in four different ABO blood groups in healthy adults remain conflicting with different results. The present study was undertaken to analyse the possible differences in the haemoglobin content and red blood cell counts in health adults in four ABO blood groups.Methods: This prospective study was undertaken in a tertiary health care facility. A total of 227 healthy students were finally included in this study for analysis. The study subjects were belonging to 18-22 years old of both genders. The haemoglobin content was measured by Sahli’s method and ABO blood group typing along with Rh D typing was carried out in all the students. The statistical analyses were carried out by using Graph-Pad Instat.Results: The mean age of the students was 19.91 years with 59.9% being males. Both haemoglobin level and red blood cells counts were significantly high in males compared to females. Blood groups A, B, AB and O was reported in 41(18.06%), 63(27.75%), 15(6.60%) and 108(47.58%) healthy students respectively.conclusion: There was no significant difference was observed in the mean haemoglobin level and red blood cells counts among the four ABO blood groups.

The optimized carbon monoxide (CO) rebreathing method (oCOR-method) is routinely used to measure total haemoglobin mass (tHbmass). The tHbmass measure is subject to a test-retest typical error of ~2%, mostly from the precision of carboxyhaemoglobin (HbCO) measurement. We hypothesized that tHbmass would be robust to differences in the bolus of CO administered during the oCOR-method. Twelve participants (ten males and two females; age 27 ± 6 yr, height 177 ± 11 cm and mass 73.9 ± 12.1 kg) completed the oCOR-method on four occasions. Different bolus of CO were administered (LOW: 0.6 ml kg(-1); MED1: 1.0 ml kg(-1) and HIGH: 1.4 ml kg(-1)); to determine the reliability of MED1, a second trial was conducted (MED2). tHbmass was found to be significantly less from the HIGH CO bolus (776 ± 148 g) when compared to the LOW CO (791 ± 149 g) or MED1 CO (788 ± 149 g) trials. MED2 CO was 785 ± 150 g. The measurement of tHbmass is repeatable to within 0.8%, but a small and notable difference was seen when using a HIGH CO bolus (1.4 to 1.9% less), potentially due to differences in CO uptake kinetics. Previously, an improved precision of the oCOR-method was thought to require a higher bolus of CO (i.e. larger Δ%HbCO), as commercial hemoximeters only estimate %HbCO levels to a single decimal place (usually ± 0.1%). With the new hemoximeter used in this study, a bolus of 1.0 ml kg(-1) allows adequate precision with acceptable safety.

Elite rowers are highly endurance trained and present with a large lean body mass (LBM), which is closely related to total haemoglobin mass (tHbmass), a major determinant of blood O2-transport. This study aims to determine the magnitude of tHbmass in elite rowers and its relation to performance parameters that are common in rowing worldwide. 13 rowers (3 lightweight) performed a 2 000 m test to evaluate maximal performance on the rowing ergometer (P2k) and an incremental test to evaluate power output at lactate 2 and 4 mmol/l (N=15). tHbmass was measured by CO-rebreathing. tHbmass amounted to 1 285±123 g (open weight) and 1 059±48 g (lightweight). Coefficients of correlation between tHbmass and power output increased with intensity, being highest for P2k (r=0.80). An increase of 100 g tHbmass is associated with an increase of 24 W in P2k between subjects. The ratio between tHbmass/LBM amounted to approximately 16 g/kg. Absolute tHbmass in elite rowers of open weight class is very high. In relation to body mass or LBM, data is similar to other endurance athletes. The relation between P2k performance and tHbmass is very large. However, it is partly mediated by body composition.

This study aimed to determine whether changes in initial restrictive pressures (IRP, tightness of the cuff before inflation with air) affect tissue oxygenation, lactate production and leg strength before, during and after knee extension exercises. The cuff was positioned on the right thigh, and the IRP of either 40-45 or 60-65 mmHg were applied randomly prior to inflating the cuff to the final restrictive pressure (the pressure reached after inflating the cuff with air). Subjects performed four sets (30, 15, 15 and 15 reps) of isotonic knee extensions with 1-min rest between sets. Tissue oxygenation and blood lactate levels were assessed prior to, during and after exercise, and leg strength was assessed pre- and postexercise. There were significant condition by time interactions (P

Haemoglobin concentration in blood is one of the most frequently measured analytes in laboratory medicine. Reference and routine methods for the determination of the haemoglobin concentration in blood are based on the conversion of haeme, haemoglobin and haemiglobin species into uniform end products. The total haemoglobin concentration in blood is measured using the absorbance of the reaction products. Traceable absorbance measurement values on the highest metrological level are a prerequisite for the calibration and evaluation of procedures with respect to their suitability for routine measurements and their potential as reference measurement procedures. For this purpose, we describe a procedure to establish traceability of spectral absorbance measurements for the haemiglobincyanide (HiCN) method and for the alkaline haematin detergent (AHD) method. The latter is characterized by a higher stability of the reaction product. In addition, the toxic hazard of cyanide, which binds to the iron ion of the haem group and thus inhibits the oxygen transport, is avoided. Traceability is established at different wavelengths by applying total least-squares analysis to derive the conventional quantity values for the absorbance from the measured values. Extrapolation and interpolation are applied to get access to the spectral regions required to characterize the Q-absorption bands of the HiCN and AHD methods, respectively. For absorbance values between 0.3 and 1.8, the contributions of absorbance measurements to the total expanded uncertainties (95% level of confidence) of absorbance measurements range from 1% to 0.4%.

A characteristic feature of complex healthy biological systems is the ability to react and adapt to minute changes in the environment. This ‘complexity’ manifests itself in highly irregular patterns of various physiological measurements. Here, we apply Multiscale Entropy (MSE) analysis to assess the complexity of systemic and cerebral near-infrared spectroscopy (NIRS) signals in a cohort of 61 critically ill preterm infants born at median (range) gestational age of 26 (23–31) weeks, before 24 h of life. We further correlate the complexity of these parameters with brain injury and mortality. Lower complexity index (CoI) of oxygenated haemoglobin (HbO2), deoxygenated haemoglobin (Hb) and tissue oxygenation index (TOI) were observed in those infants who developed intraventricular haemorrhage (IVH) compared to those who did not (P = 0.002, P = 0.010 and P = 0.038, respectively). Mean CoI of HbO2, Hb and total haemoglobin index (THI) were lower in those infants who died compared to those who survived (P = 0.012, P = 0.004 and P = 0.003, respectively). CoI-HbO2 was an independent predictor of IVH (P = 0.010). Decreased complexity of brain signals was associated with mortality and brain injury. Measurement of brain signal complexity in preterm infants is feasible and could represent a significant advance in the brain-oriented care.

Introduction Haemoglobin is a key determinant of maximal oxygen uptake. This study's objective was to assess total haemoglobin mass (tHb-mass), as well as blood volume and morphological indices in athletes training different sports disciplines. Material and methods This study was conducted on 176 endurance and non-endurance athletes (males and females). tHb-mass, blood volume (BV), plasma volume (PV), and red cell volume (RCV) were determined by optimized carbon monoxide rebreathing method. Haemoglobin concentration (Hb), haematocrit (Hct), red blood count (RBC) were also determined. Results In endurance sports, gender regardless, no significant differences in relative mean values of tHb-mass (12.8–13.1 g/kg – males; 10.4–10.6 g/kg – females), BV (90.8–94.0 ml/kg – males; 82.7–86.9 ml/kg – females), RCV (36.6–38.0 ml/kg – males; 31.1–31.5 ml/kg – females) or of PV in males (54.2–56.4 ml/kg) were observed. The above indices’ relative values, gender regardless, were significantly lower in judo (11.2 ±0.7 g/kg, 81.8 ±5.9 ml/kg, 48.6 ±4.5 ml/kg and 33.1 ±2.0 ml/kg – males; 9.3 ±0.7 g/kg, 74.3 ±5.6 ml/kg, 46.4 ±4.0 ml/kg and 27.9 ±2.1 ml/kg – females) compared to endurance sports (p < 0.001). No substantial differences were observed in morphological blood indices in males, whereas this differentiation was found between certain sports in female athletes. Conclusions The lack of differences in tHb-mass, BV, PV and RCV in endurance sports and presence of this differentiation between various sports shows that the types of training might affect levels of mentioned indices. Measurements of tHb-mass and BV parameters prove Hb, Hct and RBC to have limited value for haematological status evaluations.

Objective: By multichannel near-infrared spectroscopy, we studied if gestational age has any influence on preterm cerebral hemodynamics, during bolus feeding.Methods: Oxy-haemoglobin (HbO2), as cerebral blood flow estimate, and the ratio between HbO2 and total haemoglobin (HbO2/HbTot), as cerebral oxygenation estimate, were assessed in 40 stable premature infants, during a 10 min bolus feeding.Results: We found no effect of any of the gestational ages studied (25–34 weeks) either on cerebral blood flow or on oxygenation, during a bolus feeding procedure.Conclusions: Bolus feeding appears not to affect cerebral hemodynamics of uncritically preterm infants, irrespective of gestational age.

Background: Globally, sickle cell disease (SCD) is one of the commonest severe monogenic disorders, due to the inheritance of two abnormal haemoglobin (beta globin) genes. SCD can cause severe pain, significant end‐organ damage, pulmonary complications, and premature death. Red blood cell (RBC) transfusions are used to treat complications of SCD, e.g. acute chest syndrome (ACS) (this often involves a single transfusion episode), or they can be part of a regular long‐term transfusion programme to prevent SCD complications. Objectives: To summarize the evidence in Cochrane Reviews of the effectiveness and safety of RBC transfusions versus no transfusion, or restrictive (to increase the total haemoglobin) versus liberal (to decrease the haemoglobin S level below a specified percentage) transfusion, for treating or preventing complications experienced by people with SCD. Methods: We included Cochrane Reviews of randomised or quasi‐randomised controlled trials published in the Cochrane Database of Systematic Reviews, that addressed various SCD complications and had RBC transfusion as an intervention or comparator. We assessed the methodological quality of included reviews according to the AMSTAR quality assessment. Main results: We included 15 Cochrane Reviews, 10 of which had no included studies with an RBC transfusion intervention (five reported RCTs with other interventions; and five contained no studies). Five of the 15 reviews included participants randomised to RBC transfusion, but in one of these reviews only 10 participants were randomised with no usable data. Four reviews (nine trials with 1502 participants) reported data comparing short‐ or long‐term RBC transfusions versus standard care, disease‐modifying agents, a restrictive versus a liberal transfusion strategy and long‐term RBC transfusions versus transfusions to treat complications. All reviews were of high quality according to AMSTAR quality assessment, however, the quality of the included trials was highly variable across outcomes. Trials were downgraded according to GRADE methodology for risk of bias, indirectness (most trials were conducted in children with HbSS), and imprecision (outcomes had wide confidence intervals). In all four reviews and all comparisons there was little or no difference in the risk of death (very low‐quality evidence). There were either no deaths or death was a rare event. Short‐term RBC transfusion versus standard care (one review: two trials, 434 participants, GRADE very low‐ to low‐quality evidence) In people undergoing low‐ to medium‐risk surgery, RBC transfusions may decrease the risk of acute chest syndrome (ACS) in people with African haplotypes compared to standard care (low‐quality evidence), but there was little or no difference in people with the Arabic haplotype (very‐low quality evidence). There was also little or no difference in the risk of other SCD‐related or transfusion‐related complications (very‐low quality evidence). Long‐term RBC transfusion versus standard care (two reviews: three trials, 405 participants, very low‐ to moderate‐quality evidence) In children and adolescents at high risk of stroke (abnormal transcranial doppler (TCD) velocities or silent cerebral infarct (SCI)), long‐term RBC transfusions probably decrease the risk of stroke (moderate‐quality evidence) and may decrease the risk of ACS and painful crisis compared to standard care (low‐quality evidence). Long‐term RBC transfusions may also decrease the risk of SCI in children with abnormal TCD velocities (low‐quality evidence), but there may be little or no difference in the risk of SCI in children with normal TCD velocities and previous SCI (low‐quality evidence). In children and adolescents already receiving long‐term RBC transfusions for preventing stroke, in comparison to standard care, continuing long‐term RBC transfusions may reduce the risk of SCI (low‐quality evidence) but we do not know whether there is a difference in the risk of stroke (very‐low quality evidence). In children with normal TCD velocities and SCI there was little or no difference in the risk of alloimmunisation or transfusion reactions, but RBC transfusions may increase the risk of iron overload (low‐quality evidence). Long‐term RBC transfusion versus RBC transfusion to treat complications (one review: one trial, 72 participants, very low‐ to low‐quality evidence) In pregnant women, long‐term RBC transfusions may decrease the risk of painful crisis compared to transfusion for complications (low‐quality evidence); but there may be little or no difference in the risk of other SCD‐related complications or transfusion reactions (very‐low quality evidence). RBC transfusion versus disease‐modifying agents (hydroxyurea) (two reviews: two trials; 254 participants, very low‐ to low‐quality evidence) For primary prevention of stroke in children, with abnormal TCD and no severe vasculopathy on magnetic resonance imaging/magnetic resonance angiography (MRI/MRA), who have received at least one year of RBC transfusions, we do not know whether there is a difference between RBC transfusion and disease‐modifying agents in the risk of stroke; SCI; ACS; or painful crisis (very‐low quality evidence). There may be little or no difference in the risk of iron overload (low‐quality evidence). Similarly, for secondary prevention of stroke in children and adolescents, we do not know whether there is a difference between these interventions in the risk of stroke; SCI; or ACS (very‐low quality evidence); but hydroxyurea with phlebotomy may increase the risk of painful crisis and global SCD serious adverse events compared to RBC transfusion (low‐quality evidence). There may be little or no difference in the risk of iron overload (low‐quality evidence). Restrictive versus liberal RBC transfusion strategy (one review: one trial; 230 participants, very low‐quality evidence) In people undergoing cholecystectomy, there was little or no difference between strategies in the risk of SCD‐related or transfusion‐related complications (very‐low quality evidence). Authors' conclusions: This overview provides support from two high‐quality Cochrane Reviews for the use of RBC transfusions in preventing stroke in children and adolescents at high risk of stroke (abnormal TCDs or SCI) and evidence that it may decrease the risk of SCI in children with abnormal TCD velocities. In addition RBC transfusions may reduce the risk of ACS and painful crisis in this population. This overview highlights the lack of high‐quality evidence in adults with SCD and the number of reviews that have no evidence for the use of RBC transfusions across a spectrum of SCD complications. Also of concern is the variable and often incomplete reporting of patient‐relevant outcomes in the included trials such as SCD‐related serious adverse events and quality of life.

Purpose The aim of this study was to determine brain oxygenation in full-term and preterm neonates using near infrared spectroscopy. Material and methods A total of 88 full-term and preterm newborn infants without hypoxic-ischaemic disorders admitted to the NICU were examined using NIRS on the first day of life and on day 28 of life. Additional measurements were taken at the end of the first week of life in the premature neonates group. Measurements of oxyhaemoglobin (HbO2), deoxyhaemoglobin (Hb), total haemoglobin (HbT) concentration and tissue oxygen saturation (Ox) were performed in 5 brain regions. Right and left frontal areas, the occipital area and right and left temporal areas were measured. Results In full-term healthy neonates a marked decrease in HbO, Hb and HbT values was observed on day 28 of life in all brain regions except the occipital area. In the neonatal period the greatest changes in brain oxygenation occurred in the right and left frontal regions of the brain. In preterm neonates constant values of HbO2 and Ox were observed in the first 28 days of life. In preterm newborn infants, as well as in full term newborn infants, similar Ox and HbO2 values were obtained on day 28 of life. Conclusions NIRS is a safe method and can be used to evaluate brain oxygenation in newborn infants. The results of these measurements are in accordance with changes in brain oxygenation in the first month of life, which are predicated on the basis of the neonate's physiology.

The use of blood doping is forbidden by the World Anti-Doping Agency. Several practices, such as blood transfusions are used to increase oxygen delivery to muscles and all of them are highly pursued. In this regard, the development of accurate methodologies for detecting these prohibited practices is one of the current aims of the anti-doping control laboratories. Flow cytometry methods are able to detect allogeneic blood transfusions but there is no official methodology available to detect autologous blood transfusions. This paper reviews protocols, including the Athlete Biological Passport, that use indirect markers to detect misuse of blood transfusions, especially autologous blood transfusions. The methods of total haemoglobin mass measurements and the detection of metabolites of blood bags plasticizers in urine are reviewed. The latter seems to be an important step forward because it is a fast screening method and it is based on urine, a fluid widely available for doping control. Other innovative approaches to blood transfusion detection are also mentioned. A combination of the reported methodologies and the implementation of the Athlete Biological Passport is becoming a promising approach.

Standing up shifts blood to dependent parts of the body, and blood vessels in the leg become filled. The orthostatic blood volume accumulation in the small vessels is relatively unknown, although these may contribute significantly. We hypothesized that in healthy humans exposed to the upright posture, volume accumulation in small blood vessels contributes significantly to the total fluid volume accumulated in the legs. Considering that near-infrared spectroscopy (NIRS) tracks postural blood volume changes within the small blood vessels of the lower leg, we evaluated the NIRS-determined changes in oxygenated (Δ[O(2)Hb]), deoxygenated (Δ[HHb]) and total haemoglobin tissue concentration (Δ[tHb]) and in total leg volume by strain-gauge plethysmography during 70 deg head-up tilt (HUT; n = 7). In a second experiment, spatial and temporal reproducibility were evaluated with three NIRS probes applied on two separate days (n = 8). In response to HUT, an initially fast increase in [O(2)Hb] was followed by a gradual decline, while [HHb] increased continuously. The increase in [tHb] during HUT was closely related to the increase in total leg volume (r(2) = 0.95 ± 0.03). After tilt back, [O(2)Hb] declined below and [HHb] remained above baseline, whereas all NIRS signals gradually returned to baseline. Spatial heterogeneity was observed, and for two probes [tHb] was highly correlated between days (r(2) = 0.92 ± 0.09 and 0.91 ± 0.12), but less for the third probe (r(2) = 0.44 ± 0.36). The results suggest a non-linear accumulation of blood volume in the small vessels of the leg, with an initial fast phase followed by a more gradual increase at least partly contributing to the relocation of fluid during orthostatic stress.

We describe innovative methodology for monitoring alterations in bladder oxygenation and haemodynamics in humans using near-infrared spectroscopy (NIRS). Concentrations of the chromophores oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin and their sum (total haemoglobin) differ during bladder contraction in health and disease. A wireless device that incorporates three paired light emitting diodes (wavelengths 760 and 850 nanometers) and silicon photodiode detector collects data transcutaneously (10 Hz) with the emitter/detector over the bladder during spontaneous bladder emptying. Data analysis indicates comparable patterns of change in chromophore concentration in healthy children and adults (positive trend during voiding, predominantly due to elevated O2Hb), but different changes in symptomatic subjects with characteristic chromophore patterns identified for voiding dysfunction due to specific pathophysiologies: bladder outlet obstruction (males), overactive bladder (females), and nonneurogenic dysfunction (children). Comparison with NIRS muscle data suggests altered bladder haemodynamics and/or oxygenation may underlie voiding dysfunction offering new insight into the causal physiology.

Background and Objectives There is no standardized method of measuring the parameters for haemolysis determination of red cell concentrate (RCC). Three haemoglobin quantification methods (automated analyser, Harboe and Drabkin’s) and two methods of haematocrit measurement (automated analyser and microcapillary centrifugation) were evaluated for use with RCC. Materials and Methods Twenty stored RCC were assayed for total haemoglobin, supernatant haemoglobin and haematocrit. Results Drabkin’s and Harboe methods were linear (r2 ≥ 0·995) over 0·015–220 g/l haemoglobin. Overestimation by Drabkin’s increased from 0% at 220 g/l to 137% at 0·015 g/l haemoglobin. Harboe values generally stayed within 6% of expected while haematology analyser values had a maximum 11% underestimation above 10 g/l. Analyser total haemoglobin was significantly lower (202 ± 22 g/l) than Drabkin’s (224 ± 24 g/l) and Harboe (222 ± 22 g/l) values. Haematocrit was greater via the analyser (65·7 ± 5·7%) than with microcapillary centrifugation (59·3 ± 5·7%). Conclusions Harboe and Drabkin’s methods are suitable for measuring total haemoglobin and supernatant haemoglobin in RCC. The analyser gave higher haematocrit values (11% on average) than did microcapillary centrifugation.

We have studied, haemoglobin A(2)' (A(2) prime), a delta chain variant haemoglobin occurring in a small percentage of individuals of African ancestry. In heterozygotes, the percentage of haemoglobin A(2)' was found to be slightly lower then the percentage of haemoglobin A(2), suggesting that the variant delta chain is synthesized at a reduced rate. When quantifying haemoglobin A(2) for the diagnosis of beta thalassaemia heterozygosity, it is essential to add together the A(2) and A(2)' to give 'total haemoglobin A(2)'. However, it not necessary to use a different reference range for total haemoglobin A(2) in A(2)' heterozygotes. When using microcolumn chromatography, A(2)' was found to be measured with A(2). On the high-performance liquid chromatography instrument studied, haemoglobin A(2)' fell in the haemoglobin S window but its retention time differed from that of haemoglobin S.

Ferastral, a new iron-poly (sorbitol-gluconic acid) complex for parenteral use has been given to 22 patients with iron deficiency anaemia. The patients were divided in two groups. Group I received a suboptimal dose of Ferastral iron corresponding to 90% of the iron calculated to normalize the haemoglobin value. Increases in total haemoglobin and also blood losses were measured. The availability of the injected iron for haemoglobin synthesis ranged from 63% to 111%. Group II received an amount of Ferastral-iron calculated to be necessary for normalization of the haemoglobin plus an additional 500 mg of Ferastral-iron. In this group the haemoglobin increase was rapid. In 7 weeks 10 out of 14 patients had reached a normal haemoglobin level.