| 1. |
- Ajan, Aida, et al.
(författare)
-
Reproducibility of Laser Doppler Flowmetry in gingival microcirculation. A study on six different protocols
- 2024
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 153
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: Laser Doppler Flowmetry (LDF) is a non-invasive technique for the assessment of tissue blood flow, but increased reproducibility would facilitate longitudinal studies. The aim of the study was to assess the interday reproducibility of Laser Doppler Flowmetry (LDF) at rest, at elevated local temperatures, and with the use of the vasodilator Methyl Nicotinate (MN) in six interconnected protocols for the measurement of the blood supply to the microvascular bed of the gingiva. Methods: Ten healthy volunteers were included. Interweek LDF measurements with custom-made acrylic splints were performed. Six protocols were applied in separate regions of interest (ROI): 1; basal LDF, 2; LDF with thermoprobe 42 degrees C, 3; LDF with thermoprobe 45 degrees C, 4; LDF with thermoprobe 42 degrees C and MN, 5; LDF with thermoprobe 45 C and MN and 6; LDF with MN. Results: Intra-individual reproducibility was assessed by the within -subject coefficient of variation (wCV) and the intraclass correlation coefficient (ICC). Basal LDF measurements demonstrated high reproducibility with wCV 11.1 in 2 min and 10.3 in 5 min. ICC was 0.9 and 0.92. wCV after heat and MN was 4.9-10.3 and ICC 0.82-0.93. The topically applied MN yielded increased blood flow. Conclusion: This is the first study evaluating the reproducibility of basal LDF compared to single or multiple vasodilatory stimuli in gingiva. Multiple collector fibers probe and stabilizing acrylic splints are recommended. Vasodilatory stimulation showed a tendency toward higher reproducibility. Furthermore, MN yields vasodilation in gingiva.
|
|
| 2. |
- Bergkvist, Max, et al.
(författare)
-
Assessment of oxygenation with polarized light spectroscopy enables new means for detecting vascular events in the skin
- 2020
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 130
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Impaired oxygenation in the skin may occur in disease states and after reconstructive surgery. We used tissue viability imaging (TiVi) to measure changes in oxygenation and deoxygenation of haemoglobin in an in vitro model and in the dermal microcirculation of healthy individuals. Materials and methods: Oxygenation was measured in human whole blood with different levels of oxygenation. In healthy subjects, changes in red blood cell concentration (C-RBC,(TiVi)), oxygenation (Delta C-OH,(TiVi)) and deoxygenation (Delta C-DOH,(TiVi)) of haemoglobin were measured during and after arterial and venous occlusion using TiVi and were compared with measurements from the enhanced perfusion and oxygen saturation system (EPOS). Results: During arterial occlusion, C-RBC,(TiVi) remained unchanged while Delta C-OH,(TiVi) decreased to -44.2 (10.4) AU (p = 0.04), as compared to baseline. After release, C-RBC,C-TiVi increased to 39.2 (18.8) AU (p < 0.001), Delta C-OH,C-TiVi increased to 38.5. During venous occlusion, C-RBC,C-TiVi increased to 28.9 (11.2) AU (p < 0.001), Delta C-OH,C-TiVi decreased to -52.2 (46.1) AU (p < 0.001) compared to baseline after 5 min of venous occlusion. There was a significant correlation between the TiVi Oxygen Mapper and EPOS, for arterial (r = 0.92, p < 0.001) and venous occlusion (r = 0.87, p < 0.001), respectively. Conclusion: This study shows that TiVi can measure trends in oxygenation and deoxygenation of haemoglobin during arterial and venous stasis in healthy individuals.
|
|
| 3. |
- Detert, Hedvig, et al.
(författare)
-
Microcirculatory response to cold stress test in the healthy hand
- 2023
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 148
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Cold sensitivity of the fingers is common in several conditions. It has been linked to digital vasospasm, microvascular dysfunction, and neural mechanisms. This study aimed to investigate the normal digital micro-vascular response to a cold stress test in healthy individuals using Laser Speckle Contrast Imaging (LSCI).Methods: Twenty-six healthy individuals, mean age 31 (SD 9) years were included. Skin perfusion of digits II-V was measured using Laser Speckle Contrast Imaging before and after a standardized cold stress test. Changes in skin perfusion from baseline were analyzed between hands, digits, and sexes.Results: Skin perfusion was significantly (p < 0.0001) affected by cold provocation in both the cold exposed and the contralateral hands in all participants of the study. This effect was significantly different between the radial (digit II and III) and the ulnar (digit V) side of the hands (p < 0.001). There was a trend towards a larger decrease in perfusion in men (ns), and a faster recovery to baseline values in women (ns). A larger inter subject variability was seen in perfusion values in women.Conclusions: The normal microvascular response to cold provocation may involve both centrally and regionally mediated processes. When exposing one hand to a cold stress test, the contralateral hand responds with simul-taneous but smaller decreases in perfusion.
|
|
| 4. |
- Girkantaite, Zivile, et al.
(författare)
-
Laser Doppler flowmetry evaluation of skin microvascular endothelial function in patients with metabolic syndrome
- 2022
-
Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 142
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Metabolic syndrome (MetS) is associated with high cardiovascular morbidity and mortality, and endothelial dysfunction is an early pathogenetic event in the MetS. Lifestyle changes and pharmacological intervention might partly restore endothelial function in MetS. Whereas an optimal non-invasive test for endothelial dysfunction is still being sought, the aim of this study was to assess the relationship between changes in skin microvascular endothelial function, detected by Laser Doppler flowmetry, and cardiovascular risk factors (CVRFs) of patients with MetS. Design and methods: 3081 patients (1865 women and 1216 men, mean age 53 ± 6 years) with MetS were enrolled in the study, which was conducted during the period of 2010–2014 at Vilnius University Hospital Santaros Klinikos. Skin microvascular endothelial function was evaluated using the Laser Doppler flowmetry in combination with the post-occlusive reactive hyperaemia test. The percentage change of flow from peak to the rest flow (PF-RF) was calculated and used as the main measure of endothelial function. Results: The study showed that decrease in flow-mediated dilatation reflected by PF-RF was associated with increased triglycerides (p = 0.002), male sex (p < 0.001), and diabetes (p = 0.002). Patients with quite a few CVRFs (body mass index ≥25 kg/m2, smoking, diabetes, arterial hypertension, a positive history of dyslipidaemia) had significantly lower PF-RF score than patients only with one of these risk factors (p < 0.001). Conclusions: Changes in skin microvascular endothelial function are significantly associated with most CVRFs and depend on the number of CVRFs.
|
|
| 5. |
- Hultman, Martin, 1992-, et al.
(författare)
-
Comprehensive imaging of microcirculatory changes in the foot during endovascular intervention - A technical feasibility study
- 2022
-
Ingår i: Microvascular Research. - Maryland Heights, MO, United States : Academic Press. - 0026-2862 .- 1095-9319. ; 141
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic limb-threatening ischemia (CLTI) has a major impact on patient's lives and is associated with a heavy health care burden with high morbidity and mortality. Treatment by endovascular intervention is mostly based on macrocirculatory information from angiography and does not consider the microcirculation. Despite successful endovascular intervention according to angiographic criteria, a proportion of patients fail to heal ischemic lesions. This might be due to impaired microvascular perfusion and variations in the supply to different angiosomes. Non-invasive optical techniques for microcirculatory perfusion and oxygen saturation imaging have the potential to provide the interventionist with additional information in real-time, supporting clinical decisions during the intervention. This study presents a novel multimodal imaging system, based on multi-exposure laser speckle contrast imaging and multi-spectral imaging, for continuous use during endovascular intervention. The results during intervention display spatiotemporal changes in the microcirculation compatible with expected physiological reactions during balloon dilation, with initially induced ischemia followed by a restored perfusion, and local administration of a vasodilator inducing hyperemia. We also present perioperative and postoperative follow-up measurements with a pulsatile microcirculation perfusion. Finally, cases of spatial heterogeneity in the observed oxygen saturation and perfusion are discussed. In conclusion, this technical feasibility study shows the potential of the methodology to characterize changes in microcirculation before, during, and after endovascular intervention.
|
|
| 6. |
- Hultman, Martin, et al.
(författare)
-
Flowmotion imaging analysis of spatiotemporal variations in skin microcirculatory perfusion
- 2023
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 146
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Flowmotion is the rhythmical variations in measured skin blood flow that arise due to global and local regulation of the vessels and can be studied using frequency analysis of time-resolved blood flow signals. It has the potential to reveal clinically useful information about microvascular diseases, but the spatial heteroge-neous nature of the microvasculature makes interpretation difficult. However, recent technological advances in multi-exposure laser speckle contrast imaging (MELSCI) enable new possibilities for simultaneously studying spatial and temporal variations in flowmotion.Aim: To develop a method for flowmotion analysis of MELSCI perfusion images. Furthermore, to investigate the spatial and temporal variations in flowmotion in forearm baseline skin perfusion.Method: In four healthy subjects, forearm skin perfusion was imaged at 15.6 fps for 10 min in baseline. The time -trace signal in each pixel was analyzed using the wavelet transform and summarized in five physiologically relevant frequency intervals, resulting in images of flowmotion. Furthermore, a method for reducing the effect of motion artifacts in the flowmotion analysis was developed.Results: The flowmotion images displayed patterns of high spatial heterogeneity that differed between the fre-quency intervals. The spatial variations in flowmotion, quantified as the coefficient of variation, was between 11 % and 31 % in four subjects. Furthermore, significant temporal variations in flowmotion were also observed, indicating the importance of a spatiotemporal analysis.Conclusion: The new imaging technique reveals significant spatial differences in flowmotion that cannot be ob-tained with single-point measurements. The results indicate that global statistics of flowmotion, such as the mean value in a large region of interest, is more representative of the microcirculation than data measured only in a single point. Therefore, imaging techniques have potential to increase the clinical usefulness of flowmotion analysis.
|
|
| 7. |
- Jonasson, Hanna, et al.
(författare)
-
Post-ischemic skin peak oxygen saturation is associated with cardiovascular risk factors: a Swedish cohort study
- 2022
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 140
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to explore the associations between skin microcirculatory function and established cardiovascular risk factors in a large Swedish cohort. As part of the Swedish CArdioPulmonary bioImage Study (SCAPIS), microcirculatory data were acquired at Linko center dot ping University hospital, Linko center dot ping, Sweden during 2016-2017. The subjects, aged 50-64 years, were randomly selected from the national population register. Microcirculatory reactivity was assessed using a 5-min arterial occlusion-release protocol. Comprehensive skin microcirculatory data were continuously acquired by using a fiberoptic probe placed on the lower right arm. After exclusion of missing data (208), 1557 subjects were remaining. Among the parameters, skin microcirculatory peak oxygen saturation after occlusion release, had the strongest relationship to the cardiovascular risk factors. The linear associations between peak oxygen saturation and cardiovascular risk factors were analyzed adjusted for age and sex. We found a negative association with peak oxygen saturation (standardized regression coefficient) for blood pressure (systolic-0.05 (95% CI:-0.10;-0.003) and diastolic-0.05 (-0.10;-0.003)), BMI-0.18 (-0.23;-0.13), waist circumference (males-0.20 (-0.32;-0.16), females-0.18 (-0.25;-0.11)), prevalent diabetes-0.31 (-0.49;-0.12), hypertension-0.30 (-0.42;-0.18), dyslipidemia-0.24 (-0.40;-0.09), fasting glucose level-0.06 (-0.12;-0.01), HbA1c-0.07 (-0.12;-0.02), triglyceride level-0.09 (-0.14;-0.04), hsCRP-0.12 (-0.17;-0.07), and current smoker versus never smoked-0.50 (-0.67;-0.34). A positive association with peak oxygen saturation was found for cholesterol level 0.05 (0.005; 0.11) and HDL 0.11 (0.06; 0.17). This is the first study showing that post-ischemic skin microvascular peak oxygen saturation is associated with virtually all established cardiovascular risk factors in a population-based middle-aged cohort.
|
|
| 8. |
- Keramidas, Michail E., Assistant Professor, et al.
(författare)
-
Finger constrictor and thermoperceptual responsiveness to localised cooling following 5 weeks of intermittent regional exposures to moderately augmented transmural vascular pressure
- 2021
-
Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319.
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To examine the effects of prolonged intermittent exposures to moderately increased transmural pressure on finger vasoreactivity and thermoperception to localised cooling. Methods: Eleven men completed a 5-week regimen (3 sessions⋅week1; 55 min⋅session1), during which the vasculature in one arm (EXP) was exposed intermittently (10-min exposure: 5-min pause) to increased trans-mural pressure (from +65 mmHg week-1 to +105 mmHg week-5). Before and after the regimen, finger cuta-neous vascular conductance (CVC), temperature (Tavg), and thermoperception (thermal sensation, discomfort and pain) were monitored during a 30-min hand cold (8 ◦C water) provocation trial. The responses of the non-trained hand were examined during an additional cold trial. Results: After the regimen, baseline finger CVC and Tavg were higher in both hands (p ≤0.01). During cooling, neither finger CVC nor Tavg were modified (p >0.05). Yet the magnitude of the cold-induced drop of CVC was augmented in both hands, and to a similar extent (p ≤0.02). The regimen alleviated thermal pain in both hands (p ≤0.02); the sensation of coldness and thermal discomfort were attenuated mainly in the EXP hand (p =0.02). Conclusions: Present findings indicate that iterative local exposures to augmented intravascular pressure do not alter finger vasoreactivity to localised cooling. The pressure training, however, might impair finger basal vasomotor tone, and aggravate the magnitude of constrictor responsiveness to cooling. The pressure training also elicits thermoperceptual desensitisation to noxious thermal stimulus. To large extent, these vascular and perceptual adjustments seem to be transferred to the cutaneous vasculature of the non-trained limb.
|
|
| 9. |
- Samils, Linda, et al.
(författare)
-
Workload and sex effects in comprehensive assessment of cutaneous microcirculation
- 2023
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 148
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Workload and sex-related differences have been proposed as factors of importance when evaluating the microcirculation. Simultaneous assessments with diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) enable a comprehensive evaluation of the microcirculation. The aim of the study was to compare the response between sexes in the microcirculatory parameters red blood cell (RBC) tissue fraction, RBC oxygen saturation, average vessel diameter, and speed-resolved perfusion during baseline, cycling, and recovery, respectively.Methods: In 24 healthy participants (aged 20 to 30 years, 12 females), cutaneous microcirculation was assessed by LDF and DRS at baseline, during a workload generated by cycling at 75 to 80 % of maximal age-predicted heart rate, and recovery, respectively.Results: Females had significantly lower RBC tissue fraction and total perfusion in forearm skin microcirculation at all phases (baseline, workload, and recovery). All microvascular parameters increased significantly during cycling, most evident in RBC oxygen saturation (34 % increase on average) and perfusion (9-fold increase in total perfusion). For perfusion, the highest speeds (>10 mm/s) increased by a factor of 31, whereas the lowest speeds (<1 mm/s) increased by a factor of 2.Conclusion: Compared to a resting state, all studied microcirculation measures increased during cycling. For perfusion, this was mainly due to increased speed, and only to a minor extent due to increased RBC tissue fraction. Skin microcirculatory differences between sexes were seen in RBC concentration and total perfusion.
|
|
| 10. |
- Spray, Stine, et al.
(författare)
-
Subacute phase of subarachnoid haemorrhage in female rats : Increased intracranial pressure, vascular changes and impaired sensorimotor function
- 2021
-
Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 135
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Early brain injury (EBI) and delayed cerebral ischemia (DCI) after subarachnoid haemorrhage (SAH) has devastating consequences but therapeutic options and the underlying pathogenesis remain poorly understood despite extensive preclinical and clinical research. One of the drawbacks of most preclinical studies to date is that the mechanisms behind DCI after SAH are studied only in male animals. In this study we therefore established a female rat model of SAH in order to determine subacute pathophysiological changes that may contribute to DCI in females. Methods: Experimental SAH was induced in female rats by intracisternal injection of 300 μL of autologous blood. Sham operation served as a control. Neurological deficits and intracranial pressure measurements were evaluated at both 1 and 2 days after surgery. Additionally, changes in cerebral vascular contractility were evaluated 2 days after surgery using wire myography. Results: SAH in female rats resulted in sensorimotor deficits and decreased general wellbeing on both day 1 and day 2 after SAH. Intracranial pressure uniformly increased in all rats subjected to SAH on day 1. On day 2 the intracranial pressure had increased further, decreased slightly or remained at the level seen on day 1. Furthermore, female rats subjected to SAH developed cortical brain edema. Cerebral arteries, isolated 2 days after SAH, exhibited increased vascular contractions to endothelin-1 and 5-carboxamidotryptamine. Conclusion: In the subacute phase after SAH in female rats, we observed increased intracranial pressure, decreased wellbeing, sensorimotor deficits, increased vascular contractility and cortical brain edema. Collectively, these pathophysiological changes may contribute to DCI after SAH in females. Previous studies reported similar pathophysiological changes for male rats in the subacute phase after SAH. Thus, prevention of these gender-independent mechanisms may provide the basis for a universal treatment strategy for DCI after SAH. Nevertheless, preclinical studies of potential therapies should employ both male and female SAH models.
|
|
| 11. |
- Zdolsek, Joachim, et al.
(författare)
-
Recruitment of efferent lymph during infusion of 20% albumin
- 2023
-
Ingår i: Microvascular Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0026-2862 .- 1095-9319. ; 148
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Intravenous infusion of hyper-oncotic 20 % albumin expands the plasma volume by approximately twice the infused volume. We investigated whether the recruited fluid stems from accelerated flow of efferent lymph, which would add protein to the plasma, or from reversed transcapillary solvent filtration, where the solvent is expected to be low in protein.Methods: We analyzed data from 27 intravenous infusions of 20 % albumin (3 mL/kg; approximately 200 mL) over 30 min given to 27 volunteers and patients. Twelve of the volunteers were also given a 5 % solution and served as controls. The pattern of blood hemoglobin, colloid osmotic pressure, and the plasma concentrations of two immunoglobulins (IgG and IgM) were studied over 5 h.Results: A decrease of the difference between the plasma colloid osmotic pressure and plasma albumin occurred during the infusions and was almost four times greater for 5 % albumin than for 20 % albumin at 40 min (P < 0.0036), which indicates that non-albumin protein enriched the plasma when 20 % was infused. Moreover, the difference between the infusion-derived dilution of the blood plasma based on hemoglobin and the two im-munoglobulins amounted to-1.9 % (-6 to +0.2) for 20 % albumin and to-4.4 % (25th-75th percentile range -8.5 to +0.2) during experiments with 5 % albumin (P < 0.001). This supports that the plasma was enriched by immunoglobulins, probably via the lymph, when 20 % was infused.Conclusions: Between half and two-thirds of the extravascular fluid that was recruited during infusion of 20 % albumin in humans consisted of protein-containing fluid consistent with efferent lymph.
|
|
