Rapid Patient-Side Evaluation of Endothelial Glycocalyx Thickness in Healthy Sedated Cats Using GlycoCheck® Software

The endothelial glycocalyx (EG) determines transvascular fluid fluxes, and influences inflammation, coagulation, and capillary blood flow. The GlycoCheck® software calculates EG thickness using sidestream dark field videomicroscopy recordings. This method has not been evaluated for use in cats. The aim of the present study was to evaluate the use of GlycoCheck® for estimating EG thickness in healthy cats, and to investigate the variability of EG thickness in this population. One hundred and one healthy research-purposed cats were included in the study. The cats were sedated, and a handheld videomicroscope, connected to GlycoCheck® software, was used to evaluate the sublingual microvasculature. The parameters measured included perfused boundary region (PBR, an indirect measurement of EG thickness) in vessels between 5 and 25 μm in diameter, valid vessel density, percentage red blood cell filling, and median red blood cell column width. Heart rate, respiratory rate, pulse oximetry and oscillometric blood pressure readings were also recorded. There were 35 neutered male cats, 11 intact males, 38 neutered females, and 17 intact females. The average age was 63 months (range, 11–160 months). Tolerance intervals for PBR (vessel diameter 5–25 μm) were 1.89–3.00 μm (95% CI, lower limit 1.76–2.04, upper limit 2.83–3.13 μm); for valid vessel density were 73.33–333.33 μm/mm2 (95% CI, lower limit 77.00–99.33, upper limit 312.67–350.33 μm/mm2); for percentage red blood cell filling were 59.85–85.07% (95% CI, lower limit 58.97–63.33, upper limit 83.07–88.20 %); and for median red blood cell column width were 5.63–8.59 μm (95% CI, lower limit 5.28–6.07, upper limit 8.14–9.51 μm). There was a negative association between median red blood cell column width and body weight (p = 0.007). The median red blood cell column was significantly wider in intact females when compared to spayed females (p = 0.033). The GlycoCheck® analysis was easily performed in healthy sedated cats. Clinical variables did not have an effect on the EG thickness. These results suggest that this technique could be valuable for evaluation of the EG and microvascular parameters in cats.

Maternal Vascular Lesions in the Placenta Predict Vascular Impairments a Decade After Delivery

Women with adverse pregnancy outcomes later experience excess hypertension and cardiovascular disease, but how the events are linked is unknown. Examination of the placenta may provide clues to vascular impairments after delivery. Maternal vascular malperfusion lesions (MVMs) were abstracted from clinical reports, validated and characterized using clinical guidelines and severity score. A total of 492 women (170 with MVMs and 322 without MVMs) participated in a study visit 8 to 10 years after delivery to assess blood pressure, cardiometabolic factors, and sublingual microvascular features using sidestream dark field imaging. Covariates included age, race, adverse pregnancy outcomes (preeclampsia, small for gestational age, and preterm birth), and health behaviors. Women with versus without MVM had a distinct sublingual microvascular profile comprised of (1) lower microvascular density (−410 μm/mm 2 , P =0.015), (2) higher red blood cell filling as a marker of perfusion (2%, P =0.004), and (3) smaller perfused boundary region (−0.07 µm, P =0.025) as a measure of glycocalyx integrity, adjusted for covariates including adverse pregnancy outcomes. Women with MVM also had higher adjusted diastolic blood pressure (+2.6 mm Hg, P =0.021), total and LDL (low-density lipoprotein)-cholesterol (+11.2 mg/dL, P =0.016; +8.7 mg/dL, P =0.031). MVM associations with subsequent cardiovascular measures did not vary by type of adverse pregnancy outcome, except among women with preterm births where blood pressure was higher only among those with MVM. Results were similar when evaluated as MVM severity. A decade after delivery, women with placental vascular lesions had an adverse cardiovascular profile comprised of microvascular rarefaction, higher blood pressure and more atherogenic lipids. Placental histopathology may reveal a woman’s early trajectory toward subsequent vascular disease.

Links between Endothelial Glycocalyx Changes and Microcirculatory Parameters in Septic Patients

The glycocalyx is an endothelial surface layer that is essential for maintaining microvascular homeostasis. Impaired integrity of the endothelial glycocalyx may be directly related to the development of microvascular dysfunction. To explore this hypothesis, we conducted a prospective observational study on adult patients diagnosed with sepsis. The study aimed to evaluate the degree of damage to the glycocalyx and to identify correlations between microcirculatory parameters and glycocalyx thickness based on capillary diameter. Sublingual microcirculation was examined using a handheld Cytocam-incident dark field video microscope. A sidestream dark field video microscope attached to a GlycoCheck monitor was used to determine the perfused boundary regions (PBRs) of sublingual blood vessels grouped by diameter (5–9 μm, 10–19 μm, and 20–25 μm). We identified significant damage to the glycocalyx in sublingual blood vessels of all the aforementioned diameters in septic patients compared to healthy age-matched controls. Furthermore, we found that the PBRs of the smallest capillaries (diameter class 5–9µm) correlated moderately and inversely with both total and perfused blood vessel densities. Collectively, our data suggest that there may be a functional relationship between damage to the endothelial glycocalyx of the smallest capillaries and alterations in the microcirculation observed in response to sepsis.

Inhaled Nitric Oxide with Intravenous Hydrocortisone Does Not Improve Microvascular Perfusion in Septic Pigs.

BackgroundCapillary flow restoration in sepsis may prevent organ dysfunction caused by a prolonged impairment of microvascular flow. The main aim of the study was to investigate the microcirculatory effect of inhaled nitric oxide (iNO) combined with intravenous hydrocortisone in a porcine model of sepsis. The second aim was to evaluate the influence of hemodynamic resuscitation with noradrenaline and crystalloids on capillary flow.Materials and MethodsIn the study, 11 piglets of Polish breed were generally anaesthetized and underwent surgical colon perforation. The animals were randomly allocated to one of three treatment groups. Group 1 received iNO and hydrocortisone, whereas Group 2 was a control group. Both groups were resuscitated with crystalloids and noradrenaline if hypotensive. Group 3 received no treatment at all.In a 30-hour period of observation, we assessed microcirculation using sidestream dark field imaging (SDF) and monitored hemodynamics with a pulmonary artery catheter.Results We found no effect of iNO with hydrocortisone on microcirculation in septic piglets. Fluid and vasopressor treatment postponed microvascular flow impairment and led to a higher microcirculatory flow index, greater proportion of perfused vessels, and perfused vessel density.ConclusionCrystalloid and vasopressor treatment postpones microvascular flow derangement and organ dysfunction in septic piglets.

Microcirculation in Patients with Takotsubo Syndrome—The Prospective CIRCUS-TTS Study

The pathophysiology of Takotsubo syndrome (TTS) is incompletely understood. A sympathetic overdrive with coronary microvascular dysfunction might play a central role. The aim of our study was to assess the status of the systemic microcirculation (MC) of patients with TTS, compared to patients with myocardial infarction (MI) and healthy subjects. The systemic microvascular function of 22 TTS patients, 20 patients with MI and 20 healthy subjects was assessed via sublingual sidestream dark-field imaging. In TTS and MI patients, measurements were performed during the acute phase (day 1, 3 and 5) and after 3 months. The measurement in healthy subjects was performed once. The assessed parameters were number of vessel crossings, number of perfused vessel crossings, proportion of perfused vessels, total vessel density and perfused vessel density. The results did not show relevant differences between the investigated groups. Some minor, albeit statistically significant, differences occurred rather randomly. The MC parameters of the TTS group did not show any relevant changes in the temporal course. A systemic microvascular dysfunction could not be identified as a contributing factor in the pathogenesis of TTS. A possible microvascular dysfunction might instead be caused by a local effect restricted to the coronary microvascular bed.

Effects of a single aerobic exercise on perfused boundary region and microvascular perfusion: a field study

The endothelium and the glycocalyx play a pivotal role in regulating microvascular function and perfusion in health and critical illness. It is unknown today, whether aerobic exercise immediately affects dimensions of the endothelial surface layer (ESL) in relation to microvascular perfusion as a physiologic adaption to increased nutritional demands. This monocentric observational study was designed to determine real-time ESL and perfusion measurements of the sublingual microcirculation using sidestream dark field imaging performed in 14 healthy subjects before and after completing a 10 km trial running distance. A novel image acquisition and analysis software automatically analysed the perfused boundary region (PBR), an inverse parameter for red blood cell (RBC) penetration of the ESL, in vessels between 5 and 25 µm diameter. Microvascular perfusion was assessed by calculating RBC filling percentage. There was no significant immediate effect of exercise on PBR and RBC filling percentage. Linear regression analysis revealed a distinct association between change of PBR and change of RBC filling percentage (regression coefficient β: − 0.026; 95% confidence interval − 0.043 to − 0.009; p = 0.006). A single aerobic exercise did not induce a change of PBR or RBC filling percentage. The endothelium of the microvasculature facilitates efficient perfusion in vessels reacting with an increased endothelial surface layer.

Comparison of Microcirculatory Perfusion in Obese and Non-Obese Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass

Obesity is a frequent comorbidity among patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Cardiac surgery with CPB impairs microcirculatory perfusion, which is associated with multiple organ failure. As microvascular function is frequently compromised in obese patients, we studied whether cardiac surgery with CPB has a more detrimental effect on microcirculatory perfusion in obese patients. Sublingual microcirculatory perfusion was measured with sidestream dark field (SDF) imaging in obese patients (body mass index ≥32 kg/m2; n = 14) without type II diabetes mellitus and in lean patients (BMI 20–25 kg/m2; n = 22) undergoing cardiac surgery with CPB. CPB reduced systolic blood pressure and mean arterial pressure more profoundly in lean compared with obese patients (SBP: 38% vs. 18%; MAP: 11% vs. 8%, p < 0.05), and both restored after weaning from CPB. No differences were present in intraoperative glucose, hematocrit, hemoglobin, lactate, and blood gas values between obese and lean patients. Microcirculatory perfusion did not differ between obese and lean patients the day before surgery. CPB decreased microcirculatory perfusion with 9% in both groups, but this was only significant in lean patients (p < 0.05). Three days following surgery, microcirculatory perfusion was restored in both groups. In conclusion, microcirculatory perfusion was equally disturbed during cardiac surgery with CPB in metabolically healthy obese patients compared to lean patients.

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system

Although acute hypoxia is of utmost pathophysiologic relevance in health and disease, studies on its effects on both the macro- and microcirculation are scarce. Herein, we provide a comprehensive analysis of the effects of acute normobaric hypoxia on human macro- and microcirculation. 20 healthy participants were enrolled in this study. Hypoxia was induced in a normobaric hypoxia chamber by decreasing the partial pressure of oxygen in inhaled air stepwisely (pO2; 21.25 kPa (0 k), 16.42 kPa (2 k), 12.63 kPa (4 k) and 9.64 kPa (6 k)). Macrocirculatory effects were assessed by cardiac output measurements, microcirculatory changes were investigated by sidestream dark-field imaging in the sublingual capillary bed and videocapillaroscopy at the nailfold. Exposure to hypoxia resulted in a decrease of systemic vascular resistance (p < 0.0001) and diastolic blood pressure (p = 0.014). Concomitantly, we observed an increase in heart rate (p < 0.0001) and an increase of cardiac output (p < 0.0001). In the sublingual microcirculation, exposure to hypoxia resulted in an increase of total vessel density, proportion of perfused vessels and perfused vessel density. Furthermore, we observed an increase in peripheral capillary density. Exposure to acute hypoxia results in vasodilatation of resistance arteries, as well as recruitment of microvessels of the central and peripheral microcirculation. The observed macro- and microcirculatory effects are most likely a result from compensatory mechanisms to ensure adequate tissue oxygenation.

Abstract 16839: Maternal Placental Vascular Malperfusion Lesions Associated With Increased Cardiometabolic Risk and Reduced Microvascular Density in Women a Decade After Delivery: Which Placental Features Matter?

Introduction: Maternal vascular malperfusion (MVM) lesions in the placenta are commonly found in women with adverse pregnancy outcomes associated with increased CVD in later life. Minimal criteria for MVM include vasculopathy, accelerated villous maturation and increased syncytial knots, and villous infarction upon pathologic examination; expanded definitions have included presence of fibrin deposition (intervillous or perivillous) or low placental weight (<10 th %). Hypothesis: Women with a history of MVM lesions would have evidence of cardiometabolic risk factors and peripheral microvascular changes a decade after delivery independent of pregnancy outcome. Methods: A total of 469 women with placental pathology data available were evaluated at 8-10 years postpartum. Placental specimens were reviewed by a perinatal pathologist. Cardiometabolic variables were measured at the time of the study visit. Sidestream dark field imaging was used to assess the sublingual microcirculation. We compared the median size (diameter) of microvessels, density (total length of perfused microvessels/mm 2 ) and penetration of red cells into the glycocalyx of vessels 5-25μm diameter (perfused boundary region, PBR) in women 8-10 years after pregnancy, using the minimal MVM criteria (compared to none). Expanded criteria were examined alone. Significance =*p<0.05 vs no MVM lesions. Results: Women with minimally defined MVM lesions in their placentas had higher diastolic blood pressure (79mmHg MVM vs. 75 mmHg No MVM*), LDL (111mg/dL MVM vs. 101 mg/dL No MVM*), Cholesterol (185 mg/dL MVM vs. 175mg/dL No MVM*) and insulin (14mg/dL MVM vs. 12mg/dL No MVM*), along with smaller-sized microvessels (median 8.75±1.1 μM vs. 9.06±0.7 μM*), and a lower density of perfused microvessels compared to women without MVM lesions (3590±1260mm/mm 2 MVM vs. 3970±820 mm/mm 2 No MVM*) a decade after delivery. Glycocalyx PBR was smaller in women with prior MVM vs. women without lesions (2.01±0.23μm vs. 2.09±0.15μm, P=0.02). Similar results were not seen in subjects with either presence of fibrin or small placenta in the absence of other MVM criteria. Discussion: Using minimal criteria MVM was associated most strongly with maternal cardiometabolic and microvascular differences a decade later.