The effects of aging and cardiovascular risk factors on microvascular function assessed by near-infrared spectroscopy

Age and sex differences in microvascular responses during reactive hyperaemia

Microvascular impairments are typical of several cardiovascular diseases. Near-infrared spectroscopy (NIRS) combined with a vascular occlusion test provides non-invasive insights into microvascular responses by monitoring skeletal muscle oxygenation changes during reactive hyperaemia. Despite increasing interest in the effects of sex and ageing on microvascular responses, evidence remains inconsistent. Therefore, the present study aimed to investigate the effects of sex and age on microvascular responsiveness. Twenty-seven participants (seven young men and seven young women; seven older men and six older women; aged 26 ± 1, 26 ± 4, 67 ± 3 and 69 ± 4 years, respectively) completed a vascular occlusion test consisting of 5 min of arterial occlusion followed by 5 min reperfusion. Oxygenation changes in the vastus lateralis were monitored by near-infrared spectroscopy. The findings revealed that both women (referring to young and older women) and older participants (referring to both men and women) exhibited lower microvascular responsiveness. Notably, both women and older participants demonstrated reduced desaturation (-38% and -59%, respectively) and reperfusion rates (-24% and -40%, respectively) along with a narrower range of tissue oxygenation (-39% and -39%, respectively) and higher minimal tissue oxygenation levels (+34% and +21%, respectively). Women additionally displayed higher values in resting (+12%) and time-to-peak (+15%) tissue oxygenation levels. In conclusion, this study confirmed decreased microvascular responses in women and older individuals. These results emphasize the importance of considering sex and age when studying microvascular responses. Further research is needed to uncover the underlying mechanisms and clinical relevance of these findings, enabling the development of tailored strategies for preserving vascular health in diverse populations.

Sex-specific microvascular and hemodynamic responses to passive limb heating in young adults

OBJECTIVE

We examined sex-specific microvascular reactivity and hemodynamic responses under conditions of augmented resting blood flow induced by passive heating compared to normal blood flow.

METHODS

Thirty-eight adults (19 females) completed a vascular occlusion test (VOT) on two occasions preceded by rest with or without passive heating in a randomized, counterbalanced order. Skeletal muscle tissue oxygenation (StO2, %) was assessed with near-infrared spectroscopy (NIRS), and the rate of desaturation and resaturation as well as maximal StO2 (StO2max) and prolonged hypersaturation (area under the curve, StO2AUC) were quantified. Before the VOT, brachial artery blood flow (BABF), vascular conductance, and relative BABF (BABF normalized to forearm lean mass) were determined. Sex × condition ANOVAs were used. A p-value ≤.05 was considered statistically significant.

RESULTS

Twenty minutes of heating increased BABF compared to the control (102.9 ± 28.3 vs. 36.0 ± 20.9 mL min-1; p < .01). Males demonstrated greater BABF than females (91.9 ± 34.0 vs. 47.0 ± 19.1 mL min-1; p < .01). There was no sex difference in normalized BABF. There were no significant interactions for NIRS-VOT outcomes, but heat did increase the rate of desaturation (-0.140 ± 0.02 vs. -0.119 ± 0.03% s-1; p < .01), whereas regardless of condition, males exhibited greater rates of resaturation and StO2max than females.

CONCLUSIONS

These results suggest that blood flow is not the primary factor causing sex differences in NIRS-VOT outcomes.

Examining Relationships between Cognitive Flexibility, Exercise Perceptions, and Cardiovascular Disease Risk Factors

Adults do not engage in enough physical activity. Investigating cognitive and physiological factors related to improving this behavior-and reducing health risks-remains a public health priority. Our objective was to assess whether cognitive flexibility influenced perceptions and choice of exercise programs and whether flexibility was associated with cardiovascular disease (CVD) risk factors. Independent sample groups of college-aged adults (18-24 yrs) participated in two studies. Data were collected on individuals' degree of cognitive flexibility (both self-reported and objectively measured), perceptions and choice of exercise programs, and health status markers known to be associated with CVD (vascular function, muscular strength, and body composition). Vascular function was assessed with a near-infrared spectroscopy device, strength was defined as handgrip, and body composition was estimated via digital circumferences. Self-reported flexibility reliably predicted individuals' choice of exercise program and perceptions of effort required for success on an exercise program. The relationships among CVD risk factors and objectively measured cognitive flexibility were not significant, demonstrating that identifying a healthy individual's degree of performance-based cognitive flexibility does not predict health status. Furthermore, although greater self-reported trait flexibility (rigidity) is known to predict higher (lower) likelihood of physical activity, this finding should not be extrapolated to also assume that flexibility (rigidity), as measured by objective cognitive tests, is associated with reduced CVD risk in healthy adults. We posit a rationale for how understanding cognitive flexibility and rigidity can play an impactful role in improving adherence to exercise prescriptions targeted to reducing risks.

Associations of physical activity types and intensity with cardiovascular diseases by age and gender among 18,730 Chinese adults

The associations of physical activity (PA) intensity and types with CVD (cardiovascular diseases) in different population are inconsistent and remains not very clear. A total of 7854 males and 10,876 females over 15 years were selected by multistage random sampling methods. In males, moderate-intensity physical activity (MPA) had no effect, while vigorous-intensity physical activity (VPA) played a significant protective role (OR = 1.319 and 0.615). However, in females, both MPA and VPA had significant protective effects (OR = 0.593 and 0.537). VPA presented as a significant protective factor in stroke patients and combined CVDs for males in all age groups; however, in females, the results suggested that, for those aged over 60-74 years, MPA was a protective factor. Furthermore, for the middle-aged or younger participants, the area under the curves (AUCs) of work, housework, and leisure activity were generally higher than that of other types, while for patients aged over 60 years, the AUCs of sedentary time and sleep activity seemed much higher. VPA had a better protective effect for preventing cardiovascular events, while the young and female population could benefit from MPA as well. Regardless of the types of PA, leisure activities were strongly recommended, and young people were much more likely to benefit from exercise than older people.

Pecan-enriched diet improves cholesterol profiles and enhances postprandial microvascular reactivity in older adults

Pecan-enriched diets have been linked to improved lipid metabolism; however, the impact of pecans on vascular health has yet to be examined. We hypothesized that 4 weeks of a pecan-enriched diet would improve fasting and postprandial blood lipids and vascular function compared with a nut-free diet. In this randomized control study, 44 older adults (59 ± 6 years) consumed 68 g of pecans/d (pecan; n = 21) or avoided all nuts (control; n = 23) for 4 weeks. At pre- and post-diet visits, fasting and postprandial blood lipids, macrovascular (by flow-mediated dilation), and microvascular (tissue saturation index reactive hyperemia [RH] kinetics by continuous-wave near-infrared spectroscopy) function were assessed. From the pre- to post-diet visit, there were greater reductions in fasting total cholesterol (pecan: -14 ± 4.0 vs control: -0.2 ± 5.4 mg/dL; P = .04), low-density lipoprotein (LDL) cholesterol (pecan: -15 ± 3.7 vs control: +1.9 ± 4.4 mg/dL; P = .01), non-high-density lipoprotein cholesterol (pecan: -15 ± 3.6 vs control: -0.5 ± 4.8 mg/dL; P = .02), LDL particle number (pecan: -126 ± 51 vs control: +43 ± 42 nmol/L; P = .01), and LDL medium (pecan: -34 ± 13 vs control: +16 ± 11 nmol/L; P < .01), for pecan vs control. Further, postprandial triglyceride was suppressed for pecan (P = .01) compared with control (P = .78). Postprandial RH slope (P = .04) and RH time to half (P = .004) was different by group, driven by improvements in pecan vs control. However, fasting macro- and microvascular function was unaffected. Daily pecan consumption for 4 weeks improved fasting and postprandial blood lipids and microvascular reactivity in older adults. Because changes in microvascular function typically precipitate macrovascular changes, long-term pecan consumption may improve vascular health and reduce risk for cardiovascular events. This trial was registered at clinicaltrials.gov (NCT04385537).

A novel scoring system combining Modified Early Warning Score with biomarkers of monocyte distribution width, white blood cell counts, and neutrophil-to-lymphocyte ratio to improve early sepsis prediction in older adults

OBJECTIVES

This study aims to investigate whether combining scoring systems with monocyte distribution width (MDW) improves early sepsis detection in older adults in the emergency department (ED).

METHODS

In this prospective observational study, we enrolled older adults aged ≥60 years who presented with confirmed infectious diseases to the ED. Three scoring systems-namely quick sepsis-related organ failure assessment (qSOFA), Modified Early Warning Score (MEWS), and National Early Warning Score (NEWS), and biomarkers including MDW, neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein (CRP), were assessed in the ED. Logistic regression models were used to construct sepsis prediction models.

RESULTS

After propensity score matching, we included 522 and 2088 patients with and without sepsis in our analysis from January 1, 2020, to September 30, 2021. NEWS ≥5 and MEWS ≥3 exhibited a moderate-to-high sensitivity and a low specificity for sepsis, whereas qSOFA score ≥2 demonstrated a low sensitivity and a high specificity. When combined with biomarkers, the NEWS-based, the MEWS-based, and the qSOFA-based models exhibited improved diagnostic accuracy for sepsis detection without CRP inclusion (c-statistics=0.842, 0.842, and 0.826, respectively). Of the three models, MEWS ≥3 with white blood cell (WBC) count ≥11 × 10⁹/L, NLR ≥8, and MDW ≥20 demonstrated the highest diagnostic accuracy in all age subgroups (c-statistics=0.886, 0.825, and 0.822 in patients aged 60-74, 75-89, and 90-109 years, respectively).

CONCLUSIONS

Our novel scoring system combining MEWS with WBC, NLR, and MDW effectively detected sepsis in older adults.

Metabolic and microvascular function assessed using near-infrared spectroscopy with vascular occlusion in women: age differences and reliability

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.

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.

Improved microvascular reactivity after aged garlic extract intake is not mediated by hydrogen sulfide in older adults at risk for cardiovascular disease: a randomized clinical trial

PURPOSE

This study aimed to investigate the effects of AGE on microvascular reactivity, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in older individuals at high risk for cardiovascular disease (CVD). Urinary thiosulfate was also investigated as an indirect marker of endogenous hydrogen sulfide (H₂S) synthesis. The study was conducted in a randomized, double-blind, crossover, and placebo-controlled way.

METHODS

Twenty-eight participants (14 male), 67 ± 6 years old with CVD risk factors, ingested 2.4 g of AGE or placebo (PLA). Near-infrared spectroscopy evaluated tissue oxygen saturation (StO₂) during a vascular occlusion test (30 s baseline, 5 min occlusion, and 2 min reperfusion). The upslope of StO₂ signal after cuff release was calculated to measure microvascular reactivity. Urinary thiosulfate levels were measured using a high-performance liquid chromatography system.

RESULTS

The upslope of StO₂ was significantly faster after AGE (1.01 ± 0.37% s^-1) intake compared to PLA (0.83 ± 0.35% s^-1; P < 0.001; d = 0.50). Relative changes in Δ% SBP from pre- to post-AGE intake (- 5.17 ± 5.77%) was significantly different compared to Δ% PLA (0.32 ± 5.99%; P = 0.001; d = 0.93). No significant changes in urinary thiosulfate concentrations were observed between interventions. Moreover, no significant gender effect in any parameter assessed was found.

CONCLUSION

This study demonstrated that a single dose of AGE improved microvascular reactivity in older adults at risk of CVD despite such an effect was not linked with urinary thiosulfate levels. This trial was registered at clinicaltrials.gov as NCT04008693 (May 19, 2020).

Macrovascular and microvascular responses to prolonged sitting with and without bodyweight exercise interruptions: A randomized cross-over trial

Exposure to uninterrupted prolonged sitting leads to macro- and microvascular complications, which can contribute to increased cardiovascular disease risk. This study investigated the macrovascular and microvascular responses to 3 h of sitting that was: (i) uninterrupted (CON); and (ii) interrupted every 20 min with 1 min light intensity half squats plus calf raises (EX). Twenty healthy participants (21 [SD: 2] years; 21.5 [SD: 1.6] kg/m²) were recruited to participate in this randomized cross-over trial. Macrovascular function was quantified using brachial-ankle pulse wave velocity (baPWV) and the lower- and upper-limb arterial stiffness index (ASI). Microvascular function was quantified as the medial gastrocnemius tissue oxygen saturation (StO₂) area under the curve (AUC) during reactive hyperemia. The baPWV did not significantly change with time (p = 0.594) or by condition (p = 0.772). The arm ASI increased by 3.6 (95% CI: 0.7 to 6.6, effect size [ES] = 0.27) with a nonsignificant condition effect (p = 0.219). There was a significant interaction effect for leg ASI (p = < 0.001), with ASI increasing (impairment) by 18.7 (95% CI: 12.1 to 25.3, ES = 0.63) for CON and decreasing (improvement) by -11.9 (95% CI: -18.5 to -5.3, ES = 0.40) for EX compared to presitting. Similarly, the AUC decreased (detrimental) by 18% (Δ = -321, 95% CI: -543 to -100, ES = 0.32) for CON and increased by 32% (Δ = 588, 95% CI: 366 to 809, ES = 0.59) for EX. The leg ASI was inversely associated with StO₂ AUC (interclass correlation coefficient: -0.66, 95% CI: -0.51 to -0.77). These preliminary findings suggest that regularly interrupting prolonged sitting with simple bodyweight exercises may help to preserve lower-limb vascular function.

Suitability of the muscle O2 resaturation parameters most used for assessing reactive hyperemia: a near-infrared spectroscopy study

Background

There is a spectrum of possibilities for analyzing muscle O₂ resaturation parameters for measurement of reactive hyperemia in microvasculature. However, there is no consensus with respect to the responsiveness of these O₂ resaturation parameters for assessing reactive hyperemia.

Objectives

This study investigates the responsiveness of the most utilized muscle O₂ resaturation parameters to assess reactive hyperemia in the microvasculature of a clinical group known to exhibit impairments of tissue O₂ saturation (StO₂).

Methods

Twenty-three healthy young adults, twenty-nine healthy older adults, and thirty-five older adults at risk of cardiovascular disease (CVD) were recruited. Near-infrared spectroscopy (NIRS) was used to assess StO₂ after a 5-min arterial occlusion challenge and the following parameters were analyzed: StO_{2slope_10s}, StO_{2slope_30s}, and StO_{2slope_until_baseline} (upslope of StO₂ over 10s and 30s and until StO₂ reaches the baseline value); time to StO_2baseline and time to StO_2max (time taken for StO₂ to reach baseline and peak values, respectively); ∆StO_2reperfusion (the difference between minimum and maximum StO₂ values); total area under the curve (StO_2AUCt); and AUC above the baseline value (StO_{2AUC_above_base}).

Results

Only StO_{2slope_10s} was significantly slower in older adults at risk for CVD compared to healthy young individuals (p < 0.001) and to healthy older adults (p < 0.001). Conversely, time to StO_2max was significantly longer in healthy young individuals than in older adult at CVD risk.

Conclusions

Our findings suggest that StO_{2slope_10s} may be a measure of reactive hyperemia, which provides clinical insight into microvascular function assessment.

Peripheral vasodilation is reduced during exercise in perimenopausal women with elevated cardiovascular risk

OBJECTIVE

The menopausal transition has a negative effect on peripheral dilation in response to various stimuli including shear stress and exercise. Whether the presence of elevated traditional cardiovascular disease (CVD) risk factors in women going through menopause exacerbates the adverse effect on peripheral vasodilation is unclear.

METHODS

Forty-four perimenopausal women with relatively low CVD risk were divided into tertiles based on atherosclerotic CVD (ASCVD) 10-year risk scores (lowest: 0.1%-0.5%, middle: 0.6%-0.9%, higher: >1%). Comparisons were made across tertile groups for the femoral artery vascular conductance (FVC) response to single-leg knee extension exercise (0, 5, 10, 15 W) as measured using Doppler ultrasound.

RESULTS

At higher exercise intensities, FVC was lower in women in the tertile group with the highest ASCVD 10-year risk scores (10 W: 6 ± 2 mL/min/mm Hg, 15 W: 8 ± 3 mL/min/mm Hg) compared to women in the lowest tertile group (10 W: 9 ± 3 mL/min/mm Hg, P = 0.01; 15 W: 12 ± 3 mL/min/mm Hg, P < 0.01) and middle tertile group (10 W: 10 ± 4 mL/min/mm Hg, P < 0.01; 15 W: 12 ± 5 mL/min/mm Hg, P < 0.01). The overall increase in FVC during exercise from 0 to 15 W remained lower (P ≤ 0.01) in women with the highest ASCVD risk scores compared to the other two tertile groups even after adjustment for chronological age, arterial stiffness, and fat-free mass adjusted aerobic fitness level.

CONCLUSION

Our results show that the presence of mild differences in ASCVD risk scores may be associated with a blunted active limb blood flow during leg exercise in mid-life women transitioning through menopause.

Microvascular responses during reactive hyperemia assessed by near-infrared spectroscopy and arterial stiffness in young, middle-aged, and older women

We investigated the effects of age on microvascular responses during reactive hyperemia and arterial stiffness in 13 young (22 ± 1 years), 12 middle-aged (42 ± 5 years), and 15 older (63 ± 2 years) women. During the vascular occlusion test (VOT), forearm tissue oxygen saturation (StO₂) was measured using near-infrared spectroscopy (NIRS). During reperfusion, the area under the curve (AUC) during hyperemia in young women (1123 ± 208% s) was significantly greater than that in middle-aged (771 ± 445% s, P = 0.024) and older women (619 ± 356% s, P = 0.001) with no differences between middle-aged and older women (P = 0.265). Cardio-ankle vascular index (CAVI) as an indicator of arterial stiffness was assessed using four-limb oscillometry. CAVI significantly increased with age (8.1 ± 0.7 in the older group, 6.0 ± 0.8 in the middle-aged group, and 5.8 ± 0.4 in the young group), with significant differences between older women and women in the other groups (P < 0.001); however, no differences in CAVI between young and middle-aged women (P = 0.484) were found. When the data of all groups were pooled, the AUC or upslope was associated with CAVI or body mass index or mean arterial pressure (all P < 0.05). To conclude, the AUC derived by NIRS measures of StO₂ during the reperfusion phase can be used as one of the evaluations of microvascular function, followed by the development of atherosclerosis in middle-aged and older women.

Is flow-mediated dilatation associated with near-infrared spectroscopy-derived magnitude of muscle O2 desaturation in healthy young and individuals at risk for cardiovascular disease?

Vascular occlusion test (VOT)-induced reactive hyperemia in brachial artery is crucial to flow-mediated dilation (FMD). Emerging studies have suggested that reactive hyperemia depends on the magnitude of the O₂ desaturation (ischemia) in downstream microvessels. Although near-infrared spectroscopy-derived tissue O₂ saturation index (TSI) has been used to assess the magnitude of ischemia, the association between FMD and the magnitude of O₂ desaturation has not been addressed. Therefore, the aim of the present study was to evaluate whether FMD correlates with the magnitude of muscle O₂ desaturation in healthy young individuals and older adults at risk for cardiovascular disease (CVD). Twenty healthy young individuals and 20 others at risk for CVD participated in the study. The magnitude of ischemic stimulus was determined by calculating the area under curve of TSI signal over 5 min of cuff occlusion period. Oxygen resaturation rate was calculated as the upslope of the TSI signal over 10 s following cuff deflation. There was no significant correlation between FMD and the magnitude of ischemic stimulus in both groups assessed (young: R = 0.327; P = 0.159 and older: R = -0.184; P = 0.436). However, a significant correlation between the magnitude of O₂ desaturation and O₂ resaturation rate in young (R = 0.555; P = 0.011) and older individuals at risk for CVD (R = 0.539; P = 0.014). In conclusion, FMD response did not correlate with the magnitude of muscle O₂ desaturation, although it seems to be partially associated with O₂ resaturation rate.