Search

Context: Diabetic retinopathy, a form of microvasculopathy, is the leading cause of the visual abnormality. However, there is no conclusive evidence of the relationship of systemic vascular dysfunction with retinal microvasculopathy. In addition, diabetes-associated cardiac autonomic neuropathy may also compromise vascular function. Aims: The present study intends to correlate arterial stiffness, endothelial function, and heart rate variability (HRV) as a standardized measure of cardiac autonomic neuropathy with diabetic retinopathy. Settings and Design: The present cross-sectional, observational study was conducted in the Department of Physiology. Materials and Methods: Twenty subjects were recruited in group 1 (T2DM, type 2 diabetes mellitus patients, without retinopathy) and group 2 (T2DM with retinopathy). The vascular parameters such as heart rate, peripheral and central blood pressure, augmentation index [AIx (%)], brachial -ankle pulse wave velocity (baPWV), and reactive hyperaemia index (RHI) were recorded. Statistical Analysis Used: Independent sample t-test (for parametric data) and Mann–Whitney U test (for non-parametric data) were employed to compare the variables of two groups. Spearman correlation was used to examine the relationship among the parameters. Linear regression analysis was performed to examine the important vascular predictor for diabetic retinopathy. Results: baPWV was significantly higher in group 2 than in group 1 and positively associated with group 2. RHI was significantly less in group 2 than group 1 and negatively associated with group 2. Among HRV metrics, standard deviation of successive differences (SDSD), root mean square of successive differences between normal heartbeats (RMSSD), and high frequency (HF) power were significantly decreased in group 2 than in group 1. SDSD, RMSSD, and HF power were negatively associated with group 2. RHI emerged as a significant predictor of diabetic retinopathy following linear regression. Conclusions: Overall, the result of the present study indicates that metabolic dysregulation of glucose may affect the normal functioning of the autonomic nervous system and vascular function. Therefore, screening of vascular function and cardiac autonomic tone may be advocated in diabetic patients in routine clinics to examine the existence of any comorbid condition, such as diabetic retinopathy, as systemic vascular changes may also affect ophthalmic vasculature. [ABSTRACT FROM AUTHOR]

Abstract We investigated the test–retest reliability of, and age‐related differences in, markers of skeletal muscle metabolism and microvascular function derived from the near‐infrared spectroscopy with vascular occlusion test (NIRS‐VOT) in younger women (YW) and middle‐aged and older women (MAOW). Seventeen YW (age 23 ± 4 years) and 17 MAOW (age 59 ± 8 years) completed this study. Participants completed identical experimental visits separated by ∼4 weeks during which the NIRS‐VOT was used to quantify the occlusion slope, minimum and maximum tissue saturation, ischaemic index, reperfusion magnitude, the reperfusion and 10‐s reperfusion slopes (slope 2 and slope 210‐s), time to max tissue saturation, and area under the reperfusion curve using the local tissue oxygen saturation signal. Except for slope 210‐s (intraclass correlation coefficient (ICC) = 0.37; coefficient of variation (CV) = 31%), time to max tissue saturation (ICC = 0.21), and ischaemic index (ICC = 0.37) for MAOW, all of the NIRS variables demonstrated good to excellent relative reliability for the YW (ICCs = 0.74–0.86) and the MAOW (ICCs = 0.51–0.87), with CVs of 2–21% and 2–22%, respectively. The occlusion slope was significantly lower, indicating accelerated deoxygenation, while maximum tissue saturation, reperfusion magnitude, and ischaemic index were significantly higher in YW versus MAOW. No other group differences were found. In conclusion, our data support the use of the NIRS‐VOT as a simple, reliable, non‐invasive technique for the assessment of peripheral skeletal muscle metabolism and microvascular function in women, with the reliability being generally greater in YW versus MAOW. Further, our data suggest that ageing is associated with lower skeletal muscle metabolism and microvascular hyperaemic responsiveness in women.

Context: Diabetic retinopathy, a form of microvasculopathy, is the leading cause of the visual abnormality. However, there is no conclusive evidence of the relationship of systemic vascular dysfunction with retinal microvasculopathy. In addition, diabetes-associated cardiac autonomic neuropathy may also compromise vascular function. Aims: The present study intends to correlate arterial stiffness, endothelial function, and heart rate variability (HRV) as a standardized measure of cardiac autonomic neuropathy with diabetic retinopathy. Settings and Design: The present cross-sectional, observational study was conducted in the Department of Physiology. Materials and Methods: Twenty subjects were recruited in group 1 (T2DM, type 2 diabetes mellitus patients, without retinopathy) and group 2 (T2DM with retinopathy). The vascular parameters such as heart rate, peripheral and central blood pressure, augmentation index [AIx (%)], brachial -ankle pulse wave velocity (baPWV), and reactive hyperaemia index (RHI) were recorded. Statistical Analysis Used: Independent sample t-test (for parametric data) and Mann–Whitney U test (for non-parametric data) were employed to compare the variables of two groups. Spearman correlation was used to examine the relationship among the parameters. Linear regression analysis was performed to examine the important vascular predictor for diabetic retinopathy. Results: baPWV was significantly higher in group 2 than in group 1 and positively associated with group 2. RHI was significantly less in group 2 than group 1 and negatively associated with group 2. Among HRV metrics, standard deviation of successive differences (SDSD), root mean square of successive differences between normal heartbeats (RMSSD), and high frequency (HF) power were significantly decreased in group 2 than in group 1. SDSD, RMSSD, and HF power were negatively associated with group 2. RHI emerged as a significant predictor of diabetic retinopathy following linear regression. Conclusions: Overall, the result of the present study indicates that metabolic dysregulation of glucose may affect the normal functioning of the autonomic nervous system and vascular function. Therefore, screening of vascular function and cardiac autonomic tone may be advocated in diabetic patients in routine clinics to examine the existence of any comorbid condition, such as diabetic retinopathy, as systemic vascular changes may also affect ophthalmic vasculature.

New Findings: What is the central question of this study?Can the near‐infrared spectroscopy with vascular occlusion test (NIRS‐VOT) reliably measure skeletal muscle metabolic and microvascular function in women?What is the main finding and its importance?The NIRS‐VOT can be used as a reliable technique for the assessment of skeletal muscle metabolism and microvascular function in women, with reliability being generally greater in younger women. These findings have important implications for the planning and development of future studies employing the NIRS‐VOT in women, and provide insights into the effects of age on these parameters in women specifically. We investigated the test–retest reliability of, and age‐related differences in, markers of skeletal muscle metabolism and microvascular function derived from the near‐infrared spectroscopy with vascular occlusion test (NIRS‐VOT) in younger women (YW) and middle‐aged and older women (MAOW). Seventeen YW (age 23 ± 4 years) and 17 MAOW (age 59 ± 8 years) completed this study. Participants completed identical experimental visits separated by ∼4 weeks during which the NIRS‐VOT was used to quantify the occlusion slope, minimum and maximum tissue saturation, ischaemic index, reperfusion magnitude, the reperfusion and 10‐s reperfusion slopes (slope 2 and slope 210‐s), time to max tissue saturation, and area under the reperfusion curve using the local tissue oxygen saturation signal. Except for slope 210‐s (intraclass correlation coefficient (ICC) = 0.37; coefficient of variation (CV) = 31%), time to max tissue saturation (ICC = 0.21), and ischaemic index (ICC = 0.37) for MAOW, all of the NIRS variables demonstrated good to excellent relative reliability for the YW (ICCs = 0.74–0.86) and the MAOW (ICCs = 0.51–0.87), with CVs of 2–21% and 2–22%, respectively. The occlusion slope was significantly lower, indicating accelerated deoxygenation, while maximum tissue saturation, reperfusion magnitude, and ischaemic index were significantly higher in YW versus MAOW. No other group differences were found. In conclusion, our data support the use of the NIRS‐VOT as a simple, reliable, non‐invasive technique for the assessment of peripheral skeletal muscle metabolism and microvascular function in women, with the reliability being generally greater in YW versus MAOW. Further, our data suggest that ageing is associated with lower skeletal muscle metabolism and microvascular hyperaemic responsiveness in women. [ABSTRACT FROM AUTHOR]

Measuring local haemodynamics in skeletal muscle has the potential to provide valuable insight into the oxygen delivery to tissue, especially during high demand situations such as exercise. The aim of this study was to compare the skeletal muscle microvascular response during post-occlusive reactive hyperaemia (PORH) with the response to exercise, each measured using near-infrared spectroscopy (NIRS) and to establish if associations exist between muscle measures and exercise capacity or sex. Participants were from a population-based cohort study, the Southall and Brent Revisited (SABRE) study. Skeletal muscle measures included changes in tissue saturation index at the onset of exercise (∆TSIBL-INC) and across the whole of exercise (∆TSIBL-EE), time to 50%, 95% and 100% PORH, rate of PORH recovery, area under the curve (AUC) and total oxygenated Haemoglobin (oxy-Hb) change during PORH. Exercise capacity was measured using a 6-min stepper test (6MST). Analysis was by multiple linear regression. In total, 558 participants completed the 6MST with NIRS measures of TSI (mean age±SD: 73 ± 7years, 59% male). A sub-set of 149 participants also undertook the arterial occlusion. Time to 100% PORH, recovery rate, AUC and ∆oxy-Hb were all associated with ∆TSIBL-EE (β-coefficient (95%CI): 0.05 (0.01, 0.09), p = 0.012; −47 (-85, −9.9), p = 0.014; 1.7 (0.62, 2.8), p = 0.002; 0.04 (0.002.0.108), p = 0.041, respectively). Time to 95% & 100% PORH, AUC and ∆oxy-Hb were all associated with ∆TSIBL-INC (β-coefficient (95%CI): −0.07 (−0.12,−0.02), p = 0.02; −0.03 (−0.05, −0.003), p = 0.028; 0.85 (0.18, 1.5), p = 0.013 & 0.05 (0.02, 0.09), p = 0.001, respectively). AUC and ∆Oxy-Hb were associated with steps achieved (β-coefficient (95%CI): 18.0 (2.3, 33.7), p = 0.025; 0.86 (0.10, 1.6), p = 0.027). ∆TSIBL-EE was associated with steps and highest VO2 (1.7 (0.49, 2.9), p = 0.006; 7.7 (3.2, 12.3), p = 0.001). ∆TSIBL-INC was associated with steps and VO2 but this difference was attenuated towards the null after adjustment for age, sex and ethnicity. ∆TSIBL-EE was greater in women (3.4 (0.4, 8.9) versus 2.1 (0.3, 7.4), p = 0.017) and ∆TSIBL-INC was lower in women versus men (2.4 (0.2, 10.2) versus 3.2 (0.2, 18.2), p = 0.016). These Local microvascular NIRS-measures are associated with exercise capacity in older adults and several measures can detect differences in microvascular reactivity between a community-based sample of men and women. [ABSTRACT FROM AUTHOR]

Measuring local haemodynamics in skeletal muscle has the potential to provide valuable insight into the oxygen delivery to tissue, especially during high demand situations such as exercise. The aim of this study was to compare the skeletal muscle microvascular response during post-occlusive reactive hyperaemia (PORH) with the response to exercise, each measured using near-infrared spectroscopy (NIRS) and to establish if associations exist between muscle measures and exercise capacity or sex. Participants were from a population-based cohort study, the Southall and Brent Revisited (SABRE) study. Skeletal muscle measures included changes in tissue saturation index at the onset of exercise (∆TSIBL-INC) and across the whole of exercise (∆TSIBL-EE), time to 50%, 95% and 100% PORH, rate of PORH recovery, area under the curve (AUC) and total oxygenated Haemoglobin (oxy-Hb) change during PORH. Exercise capacity was measured using a 6-min stepper test (6MST). Analysis was by multiple linear regression. In total, 558 participants completed the 6MST with NIRS measures of TSI (mean age±SD: 73 ± 7years, 59% male). A sub-set of 149 participants also undertook the arterial occlusion. Time to 100% PORH, recovery rate, AUC and ∆oxy-Hb were all associated with ∆TSIBL-EE (β-coefficient (95%CI): 0.05 (0.01, 0.09), p = 0.012; −47 (-85, −9.9), p = 0.014; 1.7 (0.62, 2.8), p = 0.002; 0.04 (0.002.0.108), p = 0.041, respectively). Time to 95% & 100% PORH, AUC and ∆oxy-Hb were all associated with ∆TSIBL-INC (β-coefficient (95%CI): −0.07 (−0.12,−0.02), p = 0.02; −0.03 (−0.05, −0.003), p = 0.028; 0.85 (0.18, 1.5), p = 0.013 & 0.05 (0.02, 0.09), p = 0.001, respectively). AUC and ∆Oxy-Hb were associated with steps achieved (β-coefficient (95%CI): 18.0 (2.3, 33.7), p = 0.025; 0.86 (0.10, 1.6), p = 0.027). ∆TSIBL-EE was associated with steps and highest VO2 (1.7 (0.49, 2.9), p = 0.006; 7.7 (3.2, 12.3), p = 0.001). ∆TSIBL-INC was associated with steps and VO2 but this difference was attenuated towards the null after adjustment for age, sex and ethnicity. ∆TSIBL-EE was greater in women (3.4 (0.4, 8.9) versus 2.1 (0.3, 7.4), p = 0.017) and ∆TSIBL-INC was lower in women versus men (2.4 (0.2, 10.2) versus 3.2 (0.2, 18.2), p = 0.016). These Local microvascular NIRS-measures are associated with exercise capacity in older adults and several measures can detect differences in microvascular reactivity between a community-based sample of men and women.

New Findings: What is the central question of this study?Are there sex differences in vascular function following induced inflammation when oestrogen is typically similar between sexes?What is the main finding and its importance?The present study suggests no sex differences in conduit artery vascular responses to acutely induced inflammation during the low‐oestrogen phase of the menstrual cycle in premenopausal women. However, women exhibit lower microvascular function than men. Overall, the results underpin the role of oestrogen in previously observed sex differences and the importance of reporting the phase in the hormonal cycle when women are studied. Sex differences in cardiovascular disease incidence in premenopausal women and age‐matched men have been attributed to the cardioprotective influence of oestrogen. However, limited knowledge exists regarding sex differences following acute inflammation when oestrogen concentrations are lower in women. We evaluated sex differences in vascular responses to induced inflammation when oestrogen concentrations are typically lower in women (early follicular phase or placebo phase of hormonal contraception). In 15 women and 14 men, interleukin‐6 (IL‐6) concentrations and vascular function [via brachial artery flow‐mediated dilatation (FMD)] were assessed at baseline (BL) and 24 (24H) and 48 hours (48H) after administration of influenza vaccine. After induction of inflammation, both sexes exhibited an increase in IL‐6 concentrations at 24H [mean (SD) BL vs. 24H: women, 0.563 (0.50) vs. 1.141 (0.65) pg/ml; men, 0.385 (0.17) vs. 1.113 (0.69) pg/ml; P < 0.05] that returned to near‐baseline concentrations by 48H (BL vs. 48H, P > 0.05). There were no sex differences in FMD, allometrically scaled FMD or IL‐6 concentrations at any time point (P > 0.05). Notably, women exhibited significantly lower microvascular function than men at every time point [P < 0.05; reactive hyperaemic area under the curve (in arbitrary units): women, BL 35,512 (14,916), 24H 34,428 (14,292) and 48H 39,467 (13,936); men, BL 61,748 (27,324), 24H 75,028 (29,051) and 48H 59,532 (13,960)]. When oestrogen concentrations are typically lower in women, women exhibit a similar inflammatory response and conduit artery function, but lower microvascular response to reactive hyperaemia, in comparison to age‐matched men. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study?Is there a racial disparity in macrovascular and/or microvascular function between young black and white women?What is the main finding and its importance?Black women (BLW) demonstrated impaired microvascular function but similar macrovascular function compared to white women (WHW). These findings suggest an identifiable racial disparity in microvascular function between BLW and WHW as early as young adulthood. Microvascular dysfunction is predictive of future cardiovascular disease (CVD) and generally precedes the development of macrovascular dysfunction. Therefore, these findings also suggest that evaluating microvascular function and CVD risk in young, otherwise healthy BLW are important, as there are known racial disparities in CVD morbidity and mortality in black adults. Black women (BLW) have a higher incidence of cardiovascular disease (CVD) morbidity and mortality compared to white women (WHW). Vascular dysfunction is a non‐traditional risk factor for CVD and BLW demonstrate impaired vascular function when compared to WHW throughout the lifespan. Several previous studies assessed macrovascular and microvascular function in young BLW compared to WHW, but there has been no recent work exploring this disparity in young women using current, up‐to‐date methodologies. Therefore, the purpose of this study was to evaluate both macrovascular and microvascular function as assessed by haemodynamic responses to flow‐mediated dilatation (FMD), following current FMD guidelines, in young adult BLW and WHW. We hypothesized that BLW would demonstrate attenuated macrovascular and microvascular responses to FMD compared to WHW. Macrovascular function was assessed as the percentage dilatation of the brachial artery following FMD occlusion‐cuff release (FMD%). Microvascular function was assessed by total reactive hyperaemia area under the curve (RH‐AUC), calculated as the cumulative increase in brachial artery blood flow above baseline following FMD occlusion‐cuff release. Participants were tested in the morning hours during the early follicular phase of their menstrual cycle. Twenty‐eight young, apparently healthy women completed the study: 17 WHW (23 ± 4 years) and 11 BLW (24 ± 5 years). FMD% was lower in BLW (WHW: 8.0 ± 1.6, BLW: 6.2 ± 2.4%; P = 0.02), but significance was abolished when FMD% was normalized for shear (WHW: 0.1230 ± 0.0388, BLW: 0.1132 ± 0.0405; P = 0.53). RH‐AUC was lower in BLW (WHW: 438 ± 133, BLW: 268 ± 66 ml/min; P < 0.001). Young, otherwise healthy BLW demonstrated impaired microvascular function compared to WHW. [ABSTRACT FROM AUTHOR]

Predictions of mortality may help in the selection of patients who benefit from intensive care. Endothelial dysfunction is partially responsible for many of the organic dysfunctions in critical illness. Reactive hyperaemia is a vascular response of the endothelium that can be measured by peripheral arterial tonometry (RH-PAT). We aimed to assess if reactive hyperaemia is affected by critical illness and if it correlates with outcomes. Prospective study with a cohort of consecutive patients admitted to an Intensive Care Unit. RH-PAT was accessed on admission and on the 7th day after admission. Early and late survivors were compared to non-survivors. The effect of RH-PAT variation on late mortality was studied by a logistic regression model. The association between RH-PAT and severity scores and biomarkers of organic dysfunction was investigated by multivariate analysis. 86 patients were enrolled. Mean ln(RHI) on admission was 0.580 and was significantly lower in patients with higher severity scores (p < 0.01) and early non-survivors (0.388; p = 0.027). The model for prediction of early-mortality estimated that each 0.1 decrease in ln(RHI) increased the odds for mortality by 13%. In 39 patients, a 2nd RH-PAT measurement was performed on the 7th day. The variation of ln(RHI) was significantly different between non-survivors and survivors (− 24.2% vs. 63.9%, p = 0.026). Ln(RHI) was significantly lower in patients with renal and cardiovascular dysfunction (p < 0.01). RH-PAT is correlated with disease severity and seems to be an independent marker of early mortality, cardiovascular and renal dysfunctions. RH-PAT variation predicts late mortality. There appears to be an RH-PAT impairment in the acute phase of severe diseases that may be reversible and associated with better outcomes. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of the study?Cuff‐occlusion duration may influence contrast‐enhanced ultrasound (CEUS) assessments of skeletal muscle microvascular blood flow responsiveness: what are the effects of 1, 3 and 5 min cuff‐occlusion on the magnitude and reliability of calf muscle microvascular blood flow responsiveness in older adults?What is the main finding and its importance?Calf muscle microvascular blood flow responsiveness was enhanced following 5 min cuff‐occlusion compared with 1 min. The reliability of post‐occlusion CEUS measurements was also improved following 5 min occlusion. The use of a standardized 5 min occlusion period should therefore be considered in future studies and clinical practice. Contrast‐enhanced ultrasound (CEUS) is increasingly used in assessments of skeletal muscle microvascular blood flow responsiveness. In response to limb cuff‐occlusion, some studies have reported significant impairments in CEUS measurements of microvascular blood flow in older adults with cardiovascular or metabolic disease, whereas others have failed to detect significant between‐group differences, which has brought the reliability of the technique into question. In the absence of a standardized CEUS protocol, there is variance in the duration of cuff‐occlusion used, which is likely to influence post‐occlusion measurements of muscle microvascular blood flow. We aimed to determine the effect of cuff‐occlusion duration by comparing the magnitude and reliability of CEUS measurements of calf muscle microvascular blood flow responsiveness in older adults (n = 15, 67 ± 11 years) following 1, 3 and 5 min occlusion periods. Microvascular blood flow (= microvascular volume × microvascular velocity) within the calf muscle was measured using real‐time destruction–replenishment CEUS. Measurements were made following thigh cuff‐occlusion (200 mmHg) periods of 1, 3 and 5 min in a random order. Microvascular blood flow was higher following 3 min (3.71 ± 1.46 aU s−1) and 5 min (3.47 ± 1.48 aU s−1) compared with 1 min (2.42 ± 1.27 aU s−1, P = 0.002), which corresponded with higher microvascular volumes after 3 and 5 min compared with 1 min. Reliability was good following 5 min (intraclass correlation coefficient (ICC) 0.49) compared with poor following 1 min (ICC 0.34) and 3 min (ICC 0.35). This study demonstrates that the magnitude and reliability of calf muscle microvascular responsiveness is enhanced using a 5 min cuff‐occlusion protocol compared with 1 min in older adults. [ABSTRACT FROM AUTHOR]

External counter-pulsation (ECP) generates sheer stress thereby improving endothelial function and anginal symptoms in coronary artery disease. Endothelial dysfunction is also involved in the pathogenesis of T2DM. The aim of this pilot study was to investigate the use of ECP at different doses in improving endothelial function and glycaemic markers in T2DM. This prospective study involved 46 subjects with T2DM randomly assigned to receive 35 sessions of ECP at different regimens (0.5 h versus 1 h) and duration (7 versus 12 weeks). Endothelial function was evaluated by reactive hyperaemia index (RHI) via peripheral arterial tonometry at the start, midpoint and end of study. Other secondary outcomes included fasting glucose, HOMA-IR, HbA1c, blood pressure, lipid profile, weight and vibration sense. There was no change in RHI across all 3 regimens of ECP individually or collectively at the end of the study (Δ RHI +0.01%, p = 0.458). Glycaemic markers also remained unchanged at endpoint. Subgroup analysis showed an improvement in RHI (Δ RHI +20.6%, p = 0.0178) in subjects with more severe endothelial dysfunction at baseline. ECP did not show a beneficial effect on endothelial function or glycemic control in this South-East Asian population with T2DM at any of the three regimens. This may partly be explained by less severe endothelial dysfunction and less insulin resistance in our population at baseline. • External counterpulsation (ECP) does not improve endothelial function nor glycaemic measures in an Asian cohort with T2DM. • An exploratory aim of ECP at 3 different regimens did not yield significant results. • Less insulin resistance and less severe endothelial dysfunction in our population may have contributed to these findings. [ABSTRACT FROM AUTHOR]

New Findings: •What is the central question of this study?What is the effect of lower leg hot water immersion on vascular ischaemia–reperfusion injury induced in the arm of young healthy humans?•What is the main finding and its importance?Lower leg hot water immersion successfully protects against vascular ischaemia–reperfusion injury in humans. This raises the possibility that targeted heating of the lower legs may be an alternative therapeutic approach to whole‐body heating that is equally efficacious at protecting against vascular ischaemia–reperfusion injury. Reperfusion that follows a period of ischaemia paradoxically reduces vasodilator function in humans and contributes to the tissue damage associated with an ischaemic event. Acute whole‐body hot water immersion protects against vascular ischaemia–reperfusion (I–R) injury in young healthy humans. However, the effect of acute lower leg heating on I–R injury is unclear. Therefore, the purpose of this study was to test the hypothesis that, compared with thermoneutral control immersion, acute lower leg hot water immersion would prevent the decrease in macro‐ and microvascular dilator functions following I–R injury in young healthy humans. Ten young healthy subjects (5 female) immersed their lower legs into a circulated water bath for 60 min under two randomized conditions: (1) thermoneutral control immersion (∼33°C) and (2) hot water immersion (∼42°C). Macrovascular (brachial artery flow‐mediated dilatation) and microvascular (forearm reactive hyperaemia) dilator functions were assessed using Doppler ultrasound at three time points: (1) pre‐immersion, (2) 60 min post‐immersion, and (3) post‐I/R (20 min of arm ischaemia followed by 20 min of reperfusion). Ischaemia–reperfusion injury reduced macrovascular dilator function following control immersion (pre‐immersion 6.0 ± 2.1% vs. post‐I/R 3.6 ± 2.1%; P < 0.05), but was well‐maintained with prior hot water immersion (pre‐immersion 5.8 ± 2.1% vs. post‐I/R 5.3 ± 2.1%; P = 0.8). Microvascular dilator function did not differ between conditions or across time. Taken together, acute lower leg hot water immersion prevents the decrease in macrovascular dilator function that occurs following I–R injury in young healthy humans. [ABSTRACT FROM AUTHOR]

Vascular endothelial function is a strong marker of cardiovascular health and it refers to the ability of the body to maintain the homeostasis of vascular tone. The endothelial cells react to mechanical and chemical stimuli modulating the smooth muscle cells relaxation. The extent of the induced vasodilation depends on the magnitude of the stimulus. During exercise, the peripheral circulation is mostly controlled by the endothelial cells response that increases the peripheral blood flow in body districts involved but also not involved with exercise. However, whether vascular adaptations occur also in the brachial artery as a result of isolated leg extension muscles (KE) training is still an open question. Repetitive changes in blood flow occurring during exercise may act as vascular training for vessels supplying the active muscle bed as well as for the vessels of body districts not directly involved with exercise. This study sought to evaluate whether small muscle mass (KE) training would induce improvements in endothelial function not only in the vasculature of the lower limb (measured at the femoral artery level in the limb directly involved with training), but also in the upper limb (measured at the brachial artery level in the limb not directly involved with training) as an effect of repetitive increments in the peripheral blood flow during training sessions. Ten young healthy participants (five females, and five males; age: 23 ± 3 years; stature: 1.70 ± 0.11 m; body mass: 66 ± 11 kg; BMI: 23 ± 1 kg ⋅ m-2) underwent an 8-week KE training study. Maximum work rate (MWR), vascular function and peripheral blood flow were assessed pre- and post-KE training by KE ergometer, flow mediated dilatation (FMD) in the brachial artery (non-trained limb), and by passive limb movement (PLM) in femoral artery (trained limb), respectively. After 8 weeks of KE training, MWR and PLM increased by 44% (p = 0.015) and 153% (p = 0.003), respectively. Despite acute increase in brachial artery blood flow during exercise occurred (+25%; p < 0.001), endothelial function did not change after training. Eight weeks of KE training improved endothelial cells response only in the lower limb (measured at the femoral artery level) directly involved with training, likely without affecting the endothelial response of the upper limb (measured at the brachial artery level) not involved with training.

Vascular endothelial function is a strong marker of cardiovascular health and it refers to the ability of the body to maintain the homeostasis of vascular tone. The endothelial cells react to mechanical and chemical stimuli modulating the smooth muscle cells relaxation. The extent of the induced vasodilation depends on the magnitude of the stimulus. During exercise, the peripheral circulation is mostly controlled by the endothelial cells response that increases the peripheral blood flow in body districts involved but also not involved with exercise. However, whether vascular adaptations occur also in the brachial artery as a result of isolated leg extension muscles (KE) training is still an open question. Repetitive changes in blood flow occurring during exercise may act as vascular training for vessels supplying the active muscle bed as well as for the vessels of body districts not directly involved with exercise. This study sought to evaluate whether small muscle mass (KE) training would induce improvements in endothelial function not only in the vasculature of the lower limb (measured at the femoral artery level in the limb directly involved with training), but also in the upper limb (measured at the brachial artery level in the limb not directly involved with training) as an effect of repetitive increments in the peripheral blood flow during training sessions. Ten young healthy participants (five females, and five males; age: 23 ± 3 years; stature: 1.70 ± 0.11 m; body mass: 66 ± 11 kg; BMI: 23 ± 1 kg ⋅ m-2) underwent an 8-week KE training study. Maximum work rate (MWR), vascular function and peripheral blood flow were assessed pre- and post-KE training by KE ergometer, flow mediated dilatation (FMD) in the brachial artery (non-trained limb), and by passive limb movement (PLM) in femoral artery (trained limb), respectively. After 8 weeks of KE training, MWR and PLM increased by 44% (p = 0.015) and 153% (p = 0.003), respectively. Despite acute increase in brachial artery blood flow during exercise occurred (+25%; p < 0.001), endothelial function did not change after training. Eight weeks of KE training improved endothelial cells response only in the lower limb (measured at the femoral artery level) directly involved with training, likely without affecting the endothelial response of the upper limb (measured at the brachial artery level) not involved with training. [ABSTRACT FROM AUTHOR]

Introduction: Vascular dysfunction due to reduced nitric oxide bioavailability plays an important role in the pathogenesis of sepsis. This meta-analysis examines evidence from published literature to evaluate whether in the adult population the presence/severity of sepsis is associated with impaired vasoreactivity. Material and methods: We performed a search of the Medline, Scopus, and EMBASE databases to identify observational studies using measurement of reactive hyperaemia in adult patients with sepsis. After data extraction using predefined protocol, qualitative synthesis of findings was performed regarding consistency of findings between methods, evidence of association between vascular reactivity and severity of sepsis, multiple organ failure, and death. A meta-analyses of standardised mean differences in vasoreactivity between groups was performed, in which data were available for relevant outcomes. Results: Eighteen studies using four methods to measure vascular reactivity from a total of 466 were included in the analysis. The pooled standardised mean difference estimate showed that septic patients had less reactive hyperaemia than controls (-2.59, 95% CI: -3.46 to -1.72; p < 0.00001), and peak hyperaemic blood flow was lower in patients with sepsis than in the control group (SMD = -1.42, 95% CI: -2.14 to -0.70; p = 0.0001). The combined SMD between non survivors and survivors was -0.36 (95% CI: -0.67 to -0.06; p = 0.02) for reactive hyperaemia and -0.70 (95% CI: -1.13 to -0.27; p = 0.001) for peak hyperaemic blood flow. Conclusions: Septic patients have attenuated vascular reactivity when compared to healthy volunteers. There are insufficient data indicating that these changes can identify patients at risk of worsening organ failure or death. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study? This study sought to determine whether enhancement of brachial artery flow‐mediated dilatation (FMD) after acute exposure to a sustained elevation in shear stress is greater when the shear stress stimulus for FMD is also sustained. What is the main finding and its importance? Brachial artery FMD in response to a sustained (handgrip exercise) and transient (reactive hyperaemia) shear stress stimulus was enhanced to a similar extent 10 min after a 30 min handgrip exercise intervention. This suggests that prior exposure to a sustained elevation in shear stress results in a similar acute augmentation of the ability of the endothelium to transduce sustained and transient shear stress stimuli. Abstract: Brief (30 min) exposure of the brachial artery (BA) to a sustained elevation in shear stress has been shown to potentiate subsequent BA flow‐mediated dilatation (FMD) in response to a transient shear stress stimulus [reactive hyperaemia (RH) FMD]. It is unknown whether matching the sustained shear stress exposure to a subsequent sustained shear stress stimulus for FMD [via handgrip exercise (SS‐FMD)] might enhance the potentiation of FMD. The purpose of the study, therefore, was to assess the impact of a 30 min handgrip exercise intervention‐induced elevation in shear stress on subsequent BA SS‐FMD versus RH‐FMD. Nineteen healthy men (22 ± 3 years) preformed a 30 min rhythmic handgrip exercise intervention on two experimental days. BA‐FMD was assessed using either an RH or a 6 min sustained shear stress stimulus created via handgrip exercise (order of visits counterbalanced) at three time points: pre‐intervention and 10 and 60 min post‐intervention. The FMD was assessed using duplex ultrasound. Shear stress was estimated as shear rate (SR = BA blood velocity/BA diameter). Data are mean ± SD. Both SS and RH‐FMD increased from pre‐intervention to 10 min post‐intervention [SS‐FMD (6 min average), from 0.11 ± 0.05 to 0.16 ± 0.08 mm; P = 0.008; Cohen's d = 0.66; and RH‐FMD, from 0.25 ± 0.1 to 0.32 ± 0.11 mm; P = 0.013; Cohen's d = 0.68]. The magnitude of enhancement in RH and SS‐FMD did not differ (change in RH versus SS‐FMD pre‐ versus 10 min post‐intervention, P = 0.344). These findings suggest that exposure to elevated shear stress via 30 min of handgrip exercise potentiates subsequent FMD in response to sustained and transient elevations in shear stress to a similar extent. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study? We aimed to examine leg vascular responses to brief periods of inactivity. What is the main finding and its importance? We demonstrate that a mere 10 min of sitting is sufficient to impair leg microvascular function (reactive hyperaemia). However, conduit artery vasodilatation (flow‐mediated dilatation) was unaffected, indicating maintained macrovascular function. Interestingly, immobile supine rest also resulted in a reduction in microvascular function alone that was prevented when calf muscle contractions were performed. Collectively, these data highlight the susceptibility of the microcirculation to short periods of inactivity and the beneficial role of skeletal muscle contraction for vascular health. Abstract: Prolonged sitting for 1–6 h has been shown to impair leg macrovascular [i.e. reduced flow‐mediated dilatation (FMD)] and microvascular (i.e. reduced reactive hyperaemia) function. These impairments appear to be mediated through reductions in shear stress. Interestingly, a reduction in shear rate has been observed as early as 10 min into sitting. However, it is unknown whether this acute reduction in shear stress is sufficient to affect vascular function. Accordingly, we studied 18 young men and assessed popliteal artery FMD and reactive hyperaemia before (Baseline) and after (PostSit) a 10 min sitting period. Popliteal artery shear rate was significantly reduced during sitting (Baseline, 62 ± 35 s−1; 10 min sitting, 27 ± 13 s−1; P < 0.001). Macrovascular function was unaffected by 10 min of sitting (Baseline, 4.4 ± 2.1%; PostSit, 4.3 ± 2.3%; P = 0.97), but microvascular function was reduced (Baseline, 4852 ± 2261 a.u.; PostSit, 3522 ± 1872 a.u.; P = 0.02). In a subset of individuals, we extended the recovery period after sitting and demonstrated that resting shear rate and reactive hyperaemia responses remained low up to 1 h post‐sitting (P < 0.001), whereas FMD was unchanged throughout (P = 0.99). Additionally, time control experiments were performed with participants in an immobile supine position, which demonstrated no change in macrovascular function (P = 0.94) but, unexpectedly, a reduction in microvascular function (P = 0.008). Importantly, when calf muscle contractions were performed during supine rest, reactive hyperaemia responses were maintained (P = 0.76), along with FMD (P = 0.88). These findings suggest that the leg microcirculation might be more vulnerable to short periods of inactivity, whereas conduit artery vasodilatation appears well maintained. Moreover, intermittent skeletal muscle contractions are beneficial for microvascular function. [ABSTRACT FROM AUTHOR]

Purpose To investigate cutaneous sensory nerve contribution to hyperaemia following chronic shear stress training. Methods Eleven males underwent a shear stress intervention (forearm occlusion 5 s, rest 10 s) for 30 min, 5 times·week −1 for 6 weeks on one arm, the other was an untreated control. Skin blood flow was measured using laser-Doppler flowmetry, and sensory nerve function was assessed with and without blockade with EMLA cream in response to 3 levels of local heating (39, 42, and 44 °C) and post-occlusive reactive hyperaemia (PORH). Results In response to local heating, EMLA treatment significantly delayed the onset of vasodilatation ( p  < 0.001), time-to-peak ( p  < 0.001), time to 39 °C ( p  < 0.02), time to 42 °C ( p  < 0.006), but not time to 44 °C ( p  > 0.2). EMLA treatment also increased time-to-peak for PORH ( p  ≤ 0.01). In the experimental limb after 6 weeks, both onset time and time to peak were shorter in response to local heating at the untreated and EMLA-treated sites (all p  < 0.001). There were no changes in time-to-peak for PORH at the untreated and EMLA-treated sites ( p  ≥ 0.4); however, the peak PORH response was reduced with EMLA treatment ( p  ≤ 0.03). The 6-week intervention increased the peak PORH at the untreated sites ( p  < 0.001) but not at EMLA-treated ( p  > 0.05) sites. Comparing the control limb before and after 6 weeks, no differences in responses occurred at either the untreated skin sites ( p  ≥ 0.9) or the EMLA-treated sites ( p  ≥ 0.9). Conclusions Sensory nerve blockade attenuated the improvements in cutaneous vascular responses to thermal hyperaemia and PORH following chronic exposure to shear stress. These data demonstrate an important role for sensory nerve function in the initiation of vasodilatation to both PORH and thermal hyperaemia, in both the time to onset and the magnitude of vasodilatation. [ABSTRACT FROM AUTHOR]

Objective. In lower limb peripheral artery disease the most commonly used method for the assessment of the main arterial system is represented by the determination of ankle-brachial index (ABI). The post-occlusive reactive hyperaemia (PORH) is a controversial method used for the evaluation of primary collateral circulation. The follow-up of these patients has an underestimated part, their quality of life. The aim of this study is to evaluate this and highlight the importance of the PORH in the sight of optimal treatment. Method. 34 patients diagnosed with lower extremity artery disease, receiving conservative treatment, the ankle-brachial index was defined with a Doppler Bistos BT-200, 8 MHz device, the PORH was evaluated with a Bidop ES-100V, an instrument which sends information for a Smart-V-Link software. To assess the quality of life we used the VascuQol-6 test. Results. The age (mean ± SD) of the patients was 67.24±9.51, 52.92% were active smokers. A significant positive correlation was found between PORH and the results of VascuQol-6 test (p=0.02, r=0.38) and an inverse correlation between ABI <0.5 and VascuQol-6 >12. We noticed a significant difference between the VascuQol-6 result at smokers and non-smokers (p=0.02). Conclusions. The quality of life can be acceptable at patients with significant stenosis on the main artery and decreased ankle-brachial index due to presence of the collateral artery system with a maintained ability of vasodilatation represented by PORH. The efficiency of the treatmet is based on quitting smoking, starting programs which are helping patients to quit smoking would be useful. [ABSTRACT FROM AUTHOR]

Summary: Purpose: When assessing brachial endothelial function by reactive hyperaemia, stopping blood flow creates a period of low‐flow‐mediated constriction (L‐FMC). As little is known about how this parameter influences flow‐mediated vasodilation (FMD), the purpose of this study was to better understand this relationship and to determine the intra‐ and interday reproducibility of brachial L‐FMC. Methods: Brachial L‐FMC and FMD were measured on 26 healthy, young adults (13 males, 13 females; 24·6 ± 2·7 years). Each participant had two assessments conducted on two separate visits, separated by a minimum of seven days. Brachial artery baseline diameter was imaged during rest. Continuous imaging of the artery was performed during the last 20 s of cuff‐occlusion to 180 s postcuff release. An L‐FMC was considered present if the relative change from pre‐occlusion baseline to L‐FMC artery diameter was less than −0·1%. Results: Overall, there was a strong, positive correlation between increased brachial L‐FMC and blunted FMD (visit 1 test 1: r = 0·758, P<0·001; visit 1 test 2: r = 0·706, P<0·001; visit 2 test 1: r = 0·836, P<0·001; visit 2 test 2: r = 0·857, P<0·001). The reproducibility of intra‐ and interday L‐FMC diameter was intraclass correlation coefficients (ICC) = 0·627, coefficient of variation (CV) = 54·4% and ICC = 0·734, CV = 43·5%, respectively. Conclusion: Vasoconstriction to low‐flow conditions influences the subsequent maximal dilation during reactive hyperaemia. However, L‐FMC is variable as evidenced by the weak intra‐ and interday reproducibility of the measure. Further research should study brachial L‐FMC reproducibility among varying populations and the implications L‐FMC has on the interpretation of FMD results. [ABSTRACT FROM AUTHOR]

Purpose: Prevalence of cardiovascular disease (CVD) is greater in South Asians (SAs) than White Europeans (WEs). Endothelial dysfunction and blunted forearm vasodilatation to environmental stressors have been implicated in CVD. We investigated whether these features are present in young SA men.Methods: In 15 SA and 16 WE men (19-23 years), we compared changes in forearm blood flow, arterial blood pressure (ABP), forearm vascular conductance (FVC), heart rate, and electrodermal resistance (EDR; sweating) following release of arterial occlusion (reactive hyperaemia endothelium-dependent) and 5 single sounds at 5-10 min intervals (stressors).Results: All were normotensive. Peak reactive hyperaemia was smaller in SAs than WEs (FVC increase: 0.36 ± 0.038 vs 0.44 ± 0.038 units; P < 0.05). Furthermore, in WEs, mean FVC increased at 5, 15, and 20 s of each sound (vasodilatation), but increased at 5 s only in SAs, decreasing by 20 s (vasoconstriction). This reflected a smaller proportion of SAs showing forearm vasodilatation at 15 s (5/15 SAs vs 11/16 WEs: P < 0.01), the remainder showing vasoconstriction. Concomitantly, WEs showed greater bradycardia and EDR changes. Intra-class correlation analyses showed that all responses were highly reproducible over five sounds in both WEs and SAs. Moreover, sound-evoked changes in ABP and FVC were negatively correlated in each ethnicity (P < 0.01). However, WEs showed preponderance of forearm vasodilatation and depressor responses; SAs showed preponderance of vasoconstriction and pressor responses.Conclusions: Endothelium-dependent vasodilatation is blunted in young SA men. This could explain their impaired forearm vasodilatation and greater pressor responses to repeated environmental stressors, so predisposing SAs to hypertension and CVD. [ABSTRACT FROM AUTHOR]

Background Impairments in macrovascular, microvascular and autonomic function are present in asymptomatic youths with clustered cardiovascular disease risk factors. This study determines the within-day reliability and between-day reliability of a single protocol to non-invasively assess these outcomes in adolescents. Methods Forty 12- to 15-year-old adolescents (20 boys) visited the laboratory in a fasted state on two occasions, approximately 1 week apart. One hour after a standardized cereal breakfast, macrovascular function was determined via flow-mediated dilation ( FMD). Heart rate variability (root mean square of successive R-R intervals; RMSSD) was determined from the ECG-gated ultrasound images acquired during the FMD protocol prior to cuff occlusion. Microvascular function was simultaneously quantified as the peak ( PRH) and total ( TRH) hyperaemic response to occlusion in the cutaneous circulation of the forearm via laser Doppler imaging. To address within-day reliability, a subset of twenty adolescents (10 boys) repeated these measures 90 min afterwards on one occasion. Results The within-day typical error and between-day typical error expressed as a coefficient of variation of these outcomes are as follows: ratio-scaled FMD, 5·1% and 10·6%; allometrically scaled FMD, 4·4% and 9·4%; PRH, 11% and 13·3%; TRH, 29·9% and 23·1%; and RMSSD, 17·6% and 17·6%. The within- and between-day test-retest correlation coefficients for these outcomes were all significant ( r > 0·54 for all). Conclusion Macrovascular, microvascular and autonomic functions can be simultaneously and non-invasively determined in adolescents using a single protocol with an appropriate degree of reproducibility. Determining these outcomes may provide greater understanding of the progression of cardiovascular disease and aid early intervention. [ABSTRACT FROM AUTHOR]

Whether oxygen should be administered acutely during ST-segment elevation myocardial infarction is debated. Despite this controversy, the possible influence of supplementary oxygen on animal models of ischaemia-reperfusion injury or cardioprotection is rarely considered. We used an in vivo mouse model of ischaemia and reperfusion to investigate the effect of ventilation with room air versus 100% oxygen. The coronary artery of anaesthetized mice was occluded for 40 min. followed by 2-hrs reperfusion. Infarct size was measured by tetrazolium staining and expressed as a percentage of area at risk, determined using Evan's blue. Unexpectedly, infarct size in mice ventilated with 100% oxygen was significantly smaller than in those ventilated with room air (33 ± 5% versus 46 ± 3%; n = 6; P < 0.01). We tested a standard protocol of 3 × 5 min. cycles of remote ischaemic preconditioning (RIPC) and found this was unable to protect mice ventilated with 100% oxygen. RIPC protocols using 2.5- or 10-min. occlusion were similarly ineffective in mice ventilated with oxygen. Similar disparate results were obtained with direct cardiac ischaemic preconditioning. In contrast, pharmacological protection using bradykinin administered at reperfusion was effective even in mice ventilated with 100% oxygen, reducing infarct size from 33 ± 5% to 21 ± 3% ( n = 4-6; P < 0.01). Laser speckle contrast imaging of blood flow and direct pO2 measurements were made in the hindlimb, but these measurements did not correlate with protection. In conclusion, ventilation protocol can have a major influence on infarct size and ischaemic preconditioning protocols in mice. [ABSTRACT FROM AUTHOR]

Caveolae and associated cavin and caveolins may govern myocardial function, together with responses to mechanical and ischaemic stresses. Abnormalities in these proteins are also implicated in different cardiovascular disorders. However, specific roles of the cavin-1 protein in cardiac and coronary responses to mechanical/metabolic perturbation remain unclear. We characterised cardiovascular impacts of cavin-1 deficiency, comparing myocardial and coronary phenotypes and responses to stretch and ischaemia-reperfusion in hearts from cavin- 1 and cavin- 1 mice. Caveolae and caveolins 1 and 3 were depleted in cavin- 1 hearts. Cardiac ejection properties in situ were modestly reduced in cavin- 1 mice. While peak contractile performance in ex vivo myocardium from cavin- 1 and cavin- 1 mice was comparable, intrinsic beating rate, diastolic stiffness and Frank-Starling behaviour (stretch-dependent diastolic and systolic forces) were exaggerated in cavin- 1 hearts. Increases in stretch-dependent forces were countered by NOS inhibition (100 µM L-NAME), which exposed negative inotropy in cavin- 1 hearts, and were mimicked by 100 µM nitroprusside. In contrast, chronotropic differences appeared largely NOS-independent. Cavin-1 deletion also induced NOS-dependent coronary dilatation, ≥3-fold prolongation of reactive hyperaemic responses, and exaggerated pressure-dependence of coronary flow. Stretch-dependent efflux of lactate dehydrogenase and cardiac troponin I was increased and induction of brain natriuretic peptide and c-Fos inhibited in cavin- 1 hearts, while ERK1/2 phospho-activation was preserved. Post-ischaemic dysfunction and damage was also exaggerated in cavin- 1 hearts. Diverse effects of cavin-1 deletion reveal important roles in both NOS-dependent and -independent control of cardiac and coronary functions, together with governing sarcolemmal fragility and myocardial responses to stretch and ischaemia. [ABSTRACT FROM AUTHOR]

• The spectral energies of skin temperature oscillations attenuate with the increase of frequency. • Degree of correlations of skin IR signal with LSCI decline as frequency increases. • Thermal wave originates from vasomotion of subcutaneous microvessels. • An algorithm is proposed to improve correlations between skin IR and LSCI signals. The digital thermal monitoring approach examines dynamic finger temperature in response to post-occlusive reactive hyperaemia (PORH) test and is a cost-effective way to study microvessels' regulatory functions. The degree of dependency between skin temperature and subcutaneous blood perfusion in the PORH test, however, remains an unsettled subject. The purpose of this study is to evaluate their correlations and explore the prospects of restoring subcutaneous blood perfusion using skin temperature readings. 10 volunteers participated the experimental study of PORH test, and subcutaneous blood perfusion and skin temperature images of hand were captured by laser speckle contrast imaging (LSCI) and infrared (IR) camera respectively. Wavelet cross-correlation (WCC) analysis of extracted LSCI and IR signals in the resting phase of PORH test revealed that as frequency increased within 0.005 ∼ 0.1 Hz, the modules of WCC reduced and phase shift increased. Based on phase shift characteristics, the distances of thermal wave propagation were estimated 0.9 mm ∼ 2.3 mm, which were basically consistent with the measurement depth of LSCI. We further demonstrated that when the frequency-dependent delay and attenuation were taken into account, the correlation of oscillations between LSCI and IR signals improved significantly. Finally, an algorithm was proposed to reconstruct IR signals, which could be used to improve the possibilities of restoring subcutaneous blood perfusion from skin temperature recordings in PORH tests. The prospective applications of this study include indirect measurement of subcutaneous blood perfusion and the assessment of microvessels' regulatory functions through skin temperature oscillations. [ABSTRACT FROM AUTHOR]

Background: Hot aches, also known as the screaming barfies in North America, are a recognised phenomenon amongst winter climbers, assumed to be triggered by the reperfusion of cold peripheries which then rapidly progresses to a systemic vasodilatory syndrome. Symptoms experienced in the hands include pain, numbness and throbbing followed by systemic symptoms such as nausea, irritability, dizziness and in extreme cases a transient loss of vision and hearing. Despite being well known amongst the winter climbing community, there are no publications in the scientific literature characterising the hot aches. Methods: A survey was posted online at http://www.ukclimbing.com between the dates of 28th September 2014 to 1st December 2014. Data was collected and analysed offline using Microsoft excel. Results: This is a descriptive epidemiological study of UK winter climbers and their experience of hot aches. We found that hot aches are experienced by 96 % of these climbers. They generally last 1-5 min, and 75 % rate them as being 3-4 (out of 5) on a pain scale. The most common local symptoms are pain (87 %), throbbing (70 %) and tingling (52 %). The most common systemic symptoms are nausea (44 %), irritability (32 %) and dizziness (20 %). Twenty percent of climbers experience hot aches in locations other than their hands. Conclusions: The hot aches are a highly predictable and consistent experience for almost all winter climbers. This study has characterised, for the first time, a recognised but previously unreported phenomenon that occurs in extreme winter climbers. The short- and long-term consequences are currently unknown and warrant further investigation. [ABSTRACT FROM AUTHOR]

Background Pressure ulcers are a major healthcare problem and caused by pressure and shear-forces. Although shear-force is understood to be a major contributing factor, no preventive interventions are specifically aimed at relieving the effect of shear on skin to improve skin viability. Methods A physical model was used to apply a combined loading of 2.4 kPa pressure and 14.5 N shear-force on skin in humans. Loading was applied on the volar aspect of both forearms for 30 min in ten healthy volunteers. One arm received loading on skin with a wound dressing, the other arm (control) received loading directly on skin. The following parameters were determined before and after loading: IL-1α/Total Protein-ratio (used as a measure of skin damage); Cutaneous blood cell flux ((CBF) measure of reactive hyperaemia); Lactate concentration (measure of tissue ischemia). Three different dressings were tested on three different days. The order of dressing application, dressing arm and start of the intervention were randomized. Results Participants mean age was 22.5±1.6 year with a BMI of 22.3±2.4 kg/m 2 . IL-1α/Total Protein-ratio of the skin was significantly lower after the application of pressure and shear when the Mepilex® ( P <0.01), Allevyn ( P <0.05) or Aquacel TM dressing ( P <0.01) was used compared with the control measurement. The Mepilex® dressing was more effective in reducing post-load IL-1α/Total Protein-ratio compared to the Allevyn dressing ( P <0.01). Post-load CBF was significantly lower when the Mepilex® or Aquacel dressing was used ( P <0.001). Both dressings induced significantly less post-load CBF than the Allevyn dressing ( P <0.01 and P <0.001, respectively). The concentration of lactate was not significantly increased after the application of pressure and shear and could not be used as a measure with this model. Conclusion This is the first in vivo study to demonstrate that the effects of pressure in combination with shear on skin viability can be improved with foam dressings. In this study, the multi-layered dressings perform better than the single-layered dressing. [ABSTRACT FROM AUTHOR]

Insulin resistance is associated with endothelial dysfunction in type 2 diabetes mellitus, which can lead to impaired vascular reactivities of both systemic and cerebral circulations. Appropriate ‘correction’ of vascular reactivity results for non-endothelium-dependent systemic effects avoids misinterpretation of endothelial function. Therefore, we ‘corrected’ vascular reactivity results and explored the potential correlations between systemic vascular reactivity, cerebrovascular reactivity and insulin resistance. In 34 patients, ‘systemic vascular reactivity’ was assessed by quantifying reactive hyperaemia. Cerebrovascular reactivity was assessed by quantifying changes in cerebral blood flow velocity during hypercapnia. To minimize the influence of non-endothelium-dependent systemic effects on vascular reactivity results, ‘corrected systemic vascular reactivity’ was calculated by normalizing systemic vascular reactivity using the measurements from the contralateral side; and cerebrovascular reactivity results were corrected by calculating percentage and absolute changes in cerebrovascular conductance index (‘percent cerebrovascular conductance index’ and ‘delta cerebrovascular conductance index’, respectively). Insulin resistance was estimated by homeostatic model assessment. Correlation between conventional cerebrovascular reactivity and systemic vascular reactivity was not significant. But correlations between ‘corrected systemic vascular reactivity’ and ‘percent cerebrovascular conductance index’ (r = 0.51; p = 0.002) and ‘corrected systemic vascular reactivity’ and ‘delta cerebrovascular conductance index’ (r = 0.50; p = 0.003) were significant. Among all vascular reactivity parameters, only ‘delta cerebrovascular conductance index’ was significantly correlated with homeostatic model assessment of insulin resistance (r = −0.38; p = 0.029). In conclusion, endothelial function in the systemic and cerebral circulations is moderately correlated, provided that vascular reactivity estimates are corrected for non-endothelium-dependent influences. [ABSTRACT FROM AUTHOR]

Purpose: We have argued that breathing 40 % O attenuates exercise hyperaemia by decreasing production of O-dependent vasodilators. However, breathing 100 % O attenuated endothelium-dependent vasodilatation evoked by acetylcholine and this effect was prevented by vitamin C, implicating reactive oxygen species (ROS). We have therefore used vitamin C to test the hypothesis that 40 % O modulates exercise hyperaemia and reactive hyperaemia independently of ROS. Method : In a cross-over study on 10 male subjects (21.1 ± 0.84 years), we measured forearm blood flow (venous occlusion plethysmography) and calculated forearm vascular conductance (FVC) at rest and following static handgrip at 60 % maximum voluntary contraction for 2 min and following arterial occlusion for 2 min, after placebo or oral vitamin C (2000 mg), and when breathing air or 40 % O. Result: During air breathing, vitamin C augmented the peak increase in FVC following static contraction, or release of arterial occlusion, by ~50 or 60 %, respectively ( P < 0.05). Breathing 40 % O in the presence of placebo attenuated post-contraction hyperaemia by ~25 % ( P < 0.05), but had no effect on reactive hyperaemia. By contrast, in the presence of vitamin C, 40 % O attenuated the peak increase in FVC following static contraction, or release of arterial occlusion by ~25 and 50 %, respectively ( P < 0.05). Conclusion: These results indicate that in young men, exercise hyperaemia following strenuous muscle contraction and reactive hyperaemia are blunted by ROS. However, they are also consistent with the view that modest hyperoxia induced by breathing 40 % O acts independently of ROS to attenuate not only post-contraction hyperaemia, but also reactive hyperaemia, by decreasing release of O-dependent vasodilators. [ABSTRACT FROM AUTHOR]

*Objective: The aim of this study was to explore the interaction between interface pressure, pressure-induced vasodilation, and reactive hyperaemia with different pressure-redistribution mattresses. *Method: A cross-sectional study was performed with a convenience sample of healthy young individuals, and healthy older individuals and inpatients, at a university hospital in Sweden. Blood flow was measured at depths of 1mm, 2mm, and 10mm using laser Doppler flowmetry and photoplethysmography. The blood flow, interface pressure and skin temperature were measured in the sacral tissue before, during, and after load while lying on one standard hospital mattress and three different pressure-redistribution mattresses. * Results: There were significant differences between the average sacral pressure, peak sacral pressure, and local probe pressure on the three pressure-redistribution mattresses, the lowest values found were with the visco-elastic foam/air mattress (23.5 ± 2.5mmHg, 49.3 ± 11.1mmHg, 29.2 ± 14.0mmHg, respectively). Blood flow, measured as pressure-induced vasodilation, was most affected in the visco- elastic foam/air group compared to the alternating pressure mattress group at tissue depths of 2mm (39.0% and 20.0%, respectively), and 10mm (56.9 % and 35.1%, respectively). Subjects in all three groups, including healthy 18-65 year olds, were identified with no pressure-induced vasodilation or reactive hyperaemia on any mattress (n=11), which is considered a high-risk blood flow response. * Conclusion: Interface pressure magnitudes considered not harmful during pressure-exposure on different pressure-redistribution mattresses can affect the microcirculation in different tissue structures. Despite having the lowest pressure values compared with the other mattresses, the visco-elastic foam/air mattress had the highest proportion of subjects with decreased blood flow. Healthy young individuals were identified with the high-risk blood flow response, suggesting an innate vulnerability to pressure exposure. Furthermore, the evaluation of pressure-redistribution support surfaces in terms of mean blood flow during and after tissue exposure is not feasible, but assessment of pressure-induced vasodilation and reactive hyperaemia could be a new way to assess individualised physiological measurements of mechanisms known to be related to pressure ulcer development. * Declaration of interest: None declared. The study was funded by the Swedish Research Council, the Faculty of Health Sciences at Linköping University, Region of Östergötland., King Gustaf V and Queen Victoria's Freemason Foundation, NovaMedTech, and the European Union Regional Development Fund. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction is an important component in the development of cardiovascular diseases. Endothelial function may be evaluated by peripheral arterial tonometry (PAT) which measures the vasodilator function in the microvasculature of the fingertip during reactive hyperaemia. The reactive hyperaemia index (RHI) is decreased in the presence of cardiovascular risk factors and thus far several studies have shown that PAT-RHI may provide reliable prediction of outcome. The technique is operator independent and easy to perform. Abnormalities measured by PAT follow the same trend as those measured by flow-mediated dilation in the brachial artery, but the two methods are not interchangeable. We have reviewed the recent literature in an effort to evaluate peripheral arterial tonometry as a method to assess the function of the endothelium and additionally suggest directions for future research. Special attention will be directed to the nitric oxide dependency of the reactive hyperaemia index obtained by peripheral arterial tonometry. [ABSTRACT FROM AUTHOR]

Early detection of non blanching erythema (pressure ulcer category I) is necessary to prevent any further skin damage. An objective method to discriminate between blanching/non blanching erythema is presently not available. The purpose of this investigation was to explore if a non invasive objective method could differentiate between blanching/non blanching erythema in the sacral area of patients undergoing hip fracture surgery. Seventy-eight patients were included. The sacral area of all patients was assessed using (i) conventional finger-press test and (ii) digital reading of the erythema index assessed with reflectance spectrophotometry. The patients were examined at admission and during 5 days postsurgery. Reflectance spectrophotometry measurements proved able to discriminate between blanching/non blanching erythema. The reliability, quantified by the intra-class correlation coefficient, was excellent between repeated measurements over the measurement period, varying between 0·82 and 0·96, and a significant change was recorded in the areas from day 1 to day 5 ( P < 0·0001). The value from the reference point did not show any significant changes over the same period ( P = 0·32). An objective method proven to identify early pressure damage to tissue can be a valuable tool in clinical practice. [ABSTRACT FROM AUTHOR]

Vascular reactivity is a surrogate marker for atherosclerosis and is predictive of cardiovascular outcome. Non-cardiovascular surgery is associated with perioperative cardiovascular complications in high-risk patients., To evaluate the impact of non-cardiovascular surgery on reactive hyperaemia and arterial endothelial function and to investigate the relationships between endothelial dysfunction and invasive (laparotomy) or minimally invasive (laparoscopic) surgery, we prospectively evaluated 106 patients undergoing abdominal surgery under general anaesthesia (71 laparotomy, 35 laparoscopy). Measurements of blood pressure, heart rate and pain (on a visual analogue scale ( VAS)) were undertaken. Brachial endothelium-dependent flow-mediated dilation ( FMD), endothelium-independent dilation, nitroglycerin ( NTG)-induced dilation and reactive hyperaemia were measured with high-resolution B-mode ultrasound on preoperative Day 1 (baseline), as well as 2 h and 1 and 7 days postoperatively., Blood pressure and heart rate were significantly higher 2 h postoperatively. Pain, as measured on the VAS, was higher ( P < 0.01) and reactive hyperaemia and FMD were significantly lower ( P < 0.001) at 2 h and 1 day postoperatively compared with values at baseline and on postoperative Day 7. By postoperative Day 7, FMD had recovered to baseline levels. Patients undergoing laparoscopic surgery had less FMD reduction on Days 1 and 7 (7.5 ± 1.5% and 7.9 ± 1.5%, respectively) compared with those undergoing laparotomy (6.4 ± 1.6% ( P = 0.001) and 7.0 ± 1.6% ( P = 0.006), respectively), consistent with potential cardiovascular benefit. Responses to NTG were stable throughout. Backward multivariate linear regression analysis indicated that FMD was independently related to age and VAS (model R = 0.486; F = 6.4; P < 0.001)., Reactive hyperaemia and arterial endothelial function are significantly reduced in the early postoperative period, particularly after laparotomy compared with laparoscopy, which may be related to postoperative cardiovascular events. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Cardiovascular Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Objective: Reactive hyperaemia after shear stress is a surrogate marker of endothelial function. However, the mechanisms controlling the dilation capacity of small peripheral resistance arteries are not well characterised. We evaluated reactive hyperaemia by peripheral artery tonometry (PAT) in the acral arteries and studied their clinical and biochemical determinants. Methods: Eight hundred sixteen subjects at intermediate to high cardiovascular risk were recruited. The reactive hyperaemia index (RHI) of small digital arteries was measured by PAT. Clinical history data, anthropometry and biochemical parameters were also analysed. We studied the associations between clinical and biochemical factors and small artery RHI. Results: HDL cholesterol and apolipoprotein A1 levels were strongly and directly correlated with an increased dilation response. Metabolic syndrome components, such as increased waist circumference, hypertriglyceridaemia and smoking, were inversely associated with RHI as were serum markers of inflammation. The predictors of small peripheral artery RHI were HDL cholesterol, which had a protective effect, and smoking, which had a negative impact. Conclusion: HDL cholesterol and apolipoprotein A1 levels had a strong, positive correlation with small artery reactive hyperaemia, whereas smoking, waist circumference and triglyceride levels were inversely associated. HDL cholesterol was the main determinant of RHI in small peripheral resistance arteries. [Copyright &y& Elsevier]

Copyright of Education. Physical Training. Sport / Ugdymas. Kûno kultûra. Sportas is the property of Lithuanian Sports University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The application of digital pulse amplitude by fingertip peripheral arterial tonometry (PAT) device in patients with erectile dysfunction (ED) has never been performed. We investigated the diagnostic value of reactive hyperaemia (RH) and augmentation index (AI) as evaluated using PAT in men with ED of any origin. A total of 40 patients underwent diagnostic investigation for ED, including dynamic penile duplex ultrasound (PDU) and PAT device. Moreover, 30 patients without ED served as controls. According to PDU cutoff at 35 cm/sec, patients were divided into vascular ( n = 30) and nonvascular ( n = 10) ED aetiology. Moreover, controls with ( n = 10) or without ( n = 20) vascular risk factors (VRFs) were studied in a separate analysis. Average RH-PAT was not different in men with or without ED ( P = 0.56) independently of VRFs. The AI was higher in men with ED compared with the controls ( P < 0.0001) as well as when controlled for the presence or absence of VRFs ( P < 0.0001). An inverse relationship between AI and PSV was also found ( r = −0.72, P < 0.0001). In conclusion, an increased AI but not an impaired RH-PAT is present in men with vascular ED independently of VRFs and may represent an early detection of vascular impairment that may precede endothelial dysfunction in populations at low risk for developing vascular ED. [ABSTRACT FROM AUTHOR]

Background: Post-occlusive skin reactive hyperaemia (PORH) is a model used to assess microvascular reactivity. This study aims to compare PORH response among pregnant hypercholesterolaemic patients with age and gestational age-matched controls. Methods: This cross sectional study involved 17 hypercholesterolaemic, pregnant women and 20 pregnant controls entering their early third trimester. Laser Doppler fluximetry (LDF) was used to measure skin perfusion. The process of PORH was performed by occluding the upper arm with an occlusion cuff at 200 mmHg for 3 minutes. Skin perfusion was recorded before, during, and after occlusion release. Baseline perfusion, time to achieve peak perfusion (Tp), peak perfusion after occlusion release (PORHpeak), and maximum change in perfusion due to occlusion (PORHmax) were recorded. Results: Serum total cholesterol (TC) was significantly different (P < 0.001) between the 2 groups: 7.25 (SEM 0.18) mmol/L for hypercholesterolaemic women and 5.54 (SEM 0.15) mmol/L for the control group. There were no significant differences in their baseline, PORHpeak', and PORHmax'. However, Tp in the hypercholesterolaemic group was significantly increased (P = 0.024) compared with the controls at 14.9 (SEM 0.6) seconds and 13.1 (SEM 0.5) seconds, respectively. Conclusion: Pregnant hypercholesterolaemic patients showed an abnormal microvascular reactivity response. Tp with ischemia was significantly increased compared with normocholesterolaemic controls. [ABSTRACT FROM AUTHOR]

Aim: Fructose intake has increased concurrent with sugar intake and this increase has been implicated in contributing to the development of metabolic syndrome risk factors. Recent evidence suggests a role for uric acid (UA) as a potential mediator via suppression of nitric oxide (NO) bioavailability. The aim of this study was to explore this hypothesis by measuring changes in UA concentration and systemic NO bioavailability as well as endothelial function in response to acute ingestion of a glucose-fructose beverage. Methods: Ten young (26.80 ± 4.80 years), non-obese (body mass index: 25.1 ± 2.55 kg m−2; percent body fat: 13.5 ± 6.9%) male subjects ingested either a glucose (100 g dextrose in 300 mL) or isocaloric glucose-fructose (glucose : fructose; 45 : 55 g in 300 mL) beverage. Blood was sampled pre- and every 15-min post-ingestion per 90 min and assayed for glucose, lactate, fructose, total nitrate/nitrate, UA and blood lipids. Forearm blood flow and pulse-wave velocity were recorded prior to and at 30 and 45 min time intervals post-ingestion, respectively, while heart rate, systolic and diastolic blood pressure were recorded every 15 min. Results: The glucose-fructose ingestion was associated with a significant ( P < 0.05) increase in plasma lactate concentration and altered free fatty acid levels when compared with glucose-only ingestion. However, UA was not significantly different ( P = 0.08) between conditions (AUC: −1018 ± 1675 vs. 2171 ± 1270 μmol L−1 per 90 min for glucose and glucose-fructose conditions respectively). Consequently, no significant ( P < 0.05) difference in endothelial function or systemic NO bioavailability was observed. Conclusion: Acute consumption of a fructose-containing beverage was not associated with significantly altered UA concentration, endothelial function or systemic NO bioavailability. [ABSTRACT FROM AUTHOR]

Aims In congestive heart failure (CHF), arterial response is regulated by endothelial molecules. The aim of this study was to evaluate whether endothelial dysfunction (ED) was a predictor of outcome in a cohort of patients with heart failure. Methods and results Endothelial function was assessed in 242 patients with CHF by forearm reactive hyperaemia measured with intermittent venous occlusion plethysmography using a mercury strain gauge. The main endpoints were: ‘total events’ (death, heart attack, angina, stroke, NYHA class IV, or hospitalization due to heart failure) analysed using Cox regression for repeated events and ‘death’. Patients were followed-up for 5 years. Post-hyperaemia forearm blood flow (PHFABF) was an independent predictor of total events [P = 0.01; hazard ratio [Exp(B)] 0.665, standard error (SE) 0.182]. Risk stratification by basal forearm blood flow (BFABF) showed that patients with basal blood flow above the median (3.03 mL min−1 100 mL−1) benefited from an increase in PHFABF, whereas in patients with a BFABF below the median, the increase in PHFABF did not diminish the risk of events. There was no relation between variations in PHFABF and death. Conclusion Post-hyperaemia forearm blood flow, as a measure of ED, is an independent predictor of major events in patients with CHF. A BFABF below the median is more predictive of an increased risk of complications. [ABSTRACT FROM PUBLISHER]