SDF Imaging Research Articles

The Relation of Calculated Plasma Volume Status to Sublingual Microcirculatory Blood Flow and Organ Injury.

The calculated plasma volume status (cPVS) was validated as a surrogate of intravascular filling. The aim of this study is to assess the cPVS in relation to sublingual perfusion and organ injury. Pre- and postoperative cPVS were obtained by determining the actual and ideal plasma volume levels in surgical patients. The sublingual microcirculation was assessed using SDF imaging, and we determined the De Backer score, the Consensus Proportion of Perfused Vessels (Consensus PPV), and the Consensus PPV (small). Our primary outcome was the assessment of the distribution of cPVS and its association with intraoperative sublingual microcirculation and postoperative complications. The median pre- and postoperative cPVS were -7.25% (IQR -14.29--1.88) and -0.4% (IQR -5.43-6.06), respectively (p < 0.001). The mean intraoperative administered fluid volume was 2.5 ± 2.5 L (1.14 L h-1). No statistically significant correlation was observed between the pre- or postoperative cPVS and sublingual microcirculation variables. Higher preoperative (OR = 1.04, p = 0.098) and postoperative cPVS (OR = 1.057, p = 0.029) were associated with postoperative organ injury and complications (sepsis (30%), anemia (24%), respiratory failure (13%), acute kidney injury (6%), hypotension (6%), stroke (3%)). The calculated PVS was associated with an increased risk of organ injury and complications in this cohort.

Development of a New-type Nail-fold Microcirculation Imaging Device

At present, there are many problems in the nail-fold microcirculation detection devices, such as huge structure, inconvenience to carry. In addition, due to the patient's body shaking, the video is difficult to keep stable in collecting with the device, which brings great difficulties to the doctor's observation. We develop a small image acquisition device for nail-fold microcirculation based on the principle of SDF imaging principle and liquid lenses technology. An annular lighting device is fixed in front of the optical system, and the overall design of the system is based on the characteristics of human fingers. The device is small, easy to carry and conform to the fingertips. It can focus quickly through a controller. It can also achieve high quality images of the nail-fold microcirculation. This study can promote the usage of nail-fold microcirculation device at the bedside. It's an efficient tool for medical workers to observe the microcirculation of patients.

Determination of baseline alveolar mucosa perfusion parameters using laser Doppler flowmetry and tissue spectrophotometry in healthy adults

Objectives: To determine the baseline perfusion parameters of the alveolar mucosa using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS) in healthy adults.Material and methods: Forty-two healthy adult subjects of either sex were tested. The perfusion of the alveolar mucosa was evaluated using a laser Doppler flowmetry and tissue spectrophotometry using O2C ‘oxygen to see’ device. The measurements encompassed the maxillary and mandibular mucosa at 20 different points.Results: The O2C device is a reliable method for noninvasive measurement of different perfusion parameters of the oral mucosa. The hemoglobin saturation values (So2 in %), as well as relative amount of hemoglobin in arbitrary units (AU) of the maxillary mucosa demonstrated lower values of that in the mandible. The flow value (AU) exhibited a significant difference in the posterior molar region only, while the velocity value (AU) showed a significant difference across all points except for the anterior region.Conclusion: the present study provides a set of brand-new perfusion parameters of the microcirculation of the alveolar mucosa using LDF-TS. The study suggests a variation of the perfusion parameters between the maxilla and the mandible. Differences in the anatomy of the blood supply, the thickness of the mucosa and the cortical bone, may be attributed to this variation. Further studies using different probes and a combination of ultrasonic measurements and SDF imaging will aid in giving a better overview of the perfusion in the oral mucosa.

Experience of Sublingual Microcirculation Evaluation in Adults Patients with Severe Dengue

BackgroundSevere microcirculatory changes are involved in the pathophysiological mechanisms that lead to irreversible final stages of dengue shock. We report our experience of the evaluation of sublingual microcirculation in adult patients with severe dengueMethodsAdults patients with severe dengue (by WHO 2009 criteria) were included. Dengue diagnostics was made by positive serology for IgM / IgG, antigen NS1 or PCR. Sublingual Microcirculation (SM) was evaluated by Sidestream Dark Field imaging. Microvascular flow index (MFI), proportion of small-perfused vessels (%SVP), heterogeneity index (HI) and Total Vascular Density were calculated. All patients received Fluids Challenge (FC) at hospital admission.ResultsSM was assessed in 10 patients. The median age was 65 years [IQR: 34–70], 60% were male. Eight patients were admitted to the ICU, of which 63% required invasive ventilatory and vasoactive support. One patient died. After the fluid challenge, the median of the %SVP was 94 [IR: 97 – 77], the median of the MFI was 2.82 [IR: 2, 85 – 2, 14]. There were not significant differences in %SVP and MFI among the patients who survived. In the deceased patient, the %SVP with continuous flow was 59, 18% and the MFI was 1, 45; these values were significantly decreased compared with patients who survived. A significant negative correlation between hematocrit and %SVP, and MFI was found.ConclusionInitial fluid challenge, that identifies and treats volume depletion, could correct microcirculation abnormalities evaluated by SDF imaging. However, in the patient who did not respond to this challenge, significant alterations of the MFI and the %SVP were evidenced. There is a need for more studies to improve our understanding of the role of microcirculation evaluation in these patients.Disclosures All authors: No reported disclosures.

Use of an Image Acquisition Stabilizer Improves Sidestream Dark Field Imaging of the Serosa during Open Gastrointestinal Surgery

Aim: To investigate whether an image acquisition stabilizer (IAS) mounted on the sidestream dark field camera (SDF) during gastrointestinal surgery improves image stability and acquisition. Methods: Serosal SDF imaging was compared with SDF imaging combined with an IAS (SDF + IAS) during gastrointestinal surgery. Stability was assessed as the image drift in pixels and the time to obtain stable images. The success rate was determined as the percentage of analyzable images after recording. The effect of negative pressure from the IAS was determined during single-spot measurements and by comparing microvascular parameters between groups. Data are presented as mean ± SD. Results: Sixty serosal measurements were performed per group; 87% were successful in the SDF group and 100% in the SDF + IAS group (p = 0.003). Image drift in the SDF group was 148 ± 36 versus 55 ± 15 pixels in the SDF + IAS group; p < 0.001. Time to stable image was 96 ± 60 s in the SDF group versus 57 ± 31 s in the SDF + IAS group; p = 0.03. No effect of negative pressure was seen. Conclusion: The use of an IAS mounted on an SDF camera during serosal microvascular assessment improves the success rate of image acquisition and stability and reduces the time to stable image with no effect on the microcirculation.

The effects of hydroxyethyl starch (130/0.4) as the priming solution on microcirculation in coronary bypass grafting (CABG) surgery

Introduction. Hydroxyethyl starch (HES) solution is used as a priming solution in cardiopulmonary bypass (CPB) on adult patients but its effects on microcirculation is unclear. Thus, the present investigation was performed to compare the effects of RL and HES as the priming solutions on microcirculation in CABG surgery. Methods. Following ethical committee approval and informed consent, 20 patients who underwent CABG surgery were included in this study. During CPB, Group RL received Ringer’s Lactate(n:10) and Group HES received HES (130/0,4)(n:10) as priming solution. Demographic, clinical and haemodynamic parameters were recorded. SDF imaging technique was used to evaluate the sublingual microcirculation. Haemodynamic variables (HR, MAP, CVP, CO, PCWP), laboratory parameters (Htc, BUN, creatinine, lactate and Kþ) and microcirculatory variables (Total vascular density-TVD (mm/ mm), microvascular flow index-MFI (AU), perfused vessel densityPVD (mm/ mm), proportion of perfused vessels-PPV (%) and heterogeneity of perfusion -PPVHI (%) of vessels were obtained after induction, before CPB, during CPB, at the end of the operation and at the 24 hour. These images have been analysed by using AVA (Automated Vascular Analysis) software. Results. In the two groups, changes in TVD and PVD values occurred during CPB period (po0.05). In the HES group, small vessels of TVD from 15.75 (13.14-17.61) to 13.40 (7.55-15.49) and PVD from 15.05 (12.27-16.96) to 12.53 (7.24-15.20) were decreased. In the RL group, small vessels of TVD from 13.23 (8.86-17.76) to 9.98 (8.36-15.65) and PVD from 13.68 (9.8818.01) to 10.68 (6.17-15.84) were decreased. While these parameters return to baseline values at the end of the surgery in the HES group, in the RL group, these changes remained until at the 24 hour. The PPV and PPVHI values did not change in both groups (p40.05). MFI in small sized vessels in group HES were lower than in group RL (po0.05) but these values did not affect in both groups at any time (p40.05) Conclusion. We concluded that HES (130/0.4) could be used as the CPB priming solution in patients undergoing cardiac surgery but it may have not some advantages to improve microcirculation.

Microvascular Glycocalyx Dimension Estimated by Automated SDF Imaging is not Related to Cardiovascular Disease

The EG regulates vascular homeostasis and has anti-atherogenic properties. SDF imaging allows for noninvasive visualization of microvessels and automated estimation of EG dimensions. We aimed to assess whether microcirculatory EG dimension is related to cardiovascular disease. Sublingual EG dimension was estimated by SDF imaging in healthy volunteers and in patients visiting an outpatient clinic for vascular medicine of a university hospital in Amsterdam, the Netherlands. EG dimension was compared among healthy volunteers, patients with CVD, and patients at low (<10%) or high risk (≥ 10%) of CVD according to the Framingham algorithm. In total 120 patients and 30 healthy volunteers were included. Patients had a mean age of 59 ± 14 years, 71 (59%) were men and 24 (20%) were black. Healthy volunteers were on average 28 ± 4 years and 19 (63%) were men. EG dimension was similar in healthy volunteers (2.04 ± 0.23 μm), low-risk patients (2.05 ± 0.24 μm, n = 39), high-risk patients (2.05 ± 0.23 μm, n = 30) and in patients with CVD (2.09 ± 0.21 μm, n = 51, p = 0.79). EG dimension was not correlated with cardiovascular risk factors. Microcirculatory EG dimension, as estimated by automated SDF imaging, is not associated with CVD, suggesting that this technique may not contribute to cardiovascular risk stratification.

Microcirculation in Sepsis: New Perspectives

Microcirculatory dysfunction has been recently recognized as a key pathophysiologic process in the evolution of sepsis. In the present review, we discuss fundamental aspects of microcirculatory abnormalities during septic shock, including pathogenic mechanisms, technological assessment, clinical correlates and potential therapies. The most important function of the microcirculation is the regulation and distribution of flow within the different organs. In septic shock, microcirculatory dysfunction may arise as a result of several factors such as endothelial dysfunction, leukocyte-endothelium interactions, coagulation and inflammatory disorders, hemorheologic abnormalities, and functional shunting. Severity and persistence of these microcirculatory abnormalities are associated with bad prognosis and are not necessarily predicted by systemic variables. The introduction of bedside techniques that allow evaluation of the microcirculation into clinical practice has opened up a new field of functional hemodynamic monitoring. Recent data suggest that microcirculatory abnormalities can be staged in severity. Some microcirculatory indices are more accurately related to morbidity and mortality, and thus a definition of clinically relevant microcirculatory abnormalities is feasible. On the other hand, although several systemic variables do not predict microcirculatory status, high norepinephrine (NE) requirements and hyperlactatemia are associated with a much higher prevalence of relevant microcirculatory derangements. Therefore, severe septic shock patients could represent a more precise target for interventions, particularly in microcirculation-oriented clinical trials. Clinical research has identified various therapeutic approaches that are successful in modifying the microcirculation. Future research must determine whether some of these approaches are successful in improving outcome of critically ill patients by recruiting the microcirculation.

Noninvasive assessment of the iridial microcirculation in rats using sidestream dark field imaging

Sidestream dark field imaging represents a novel, noninvasive method to study the microcirculation in humans and animals. To-date, it has been used extensively in various peripheral tissues (e.g. sublingual area, intestinal mucosa), however no data for the ocular vasculature, including the iridial microcirculation, are currently available. Therefore, the aim of this study was to examine the reliability and reproducibility of sidestream dark field imaging within the iridial microcirculation in experimental animals. Male Lewis rats were anaesthetized and the iris microvasculature was observed using an sidestream dark field probe gently placed against a cover slip covering the right eye. All video sequences recorded were analysed off-line by using AVA 3.0 software (MicroVision Medical, Amsterdam, The Netherlands). Results are expressed as mean (±SE) or median (interquartile range). Clear images were recorded from each animal and the total number of analysable video sequences was 50. All raw data for selected vessel density parameters passed normality test. The total all and small vessel density (in mm mm(-2) ) were 22,6 (±0,58) and 19,6 (±0,68), respectively. The perfused all and small vessel density were 20,9 (±0,61) and 19,1 (±0,65), respectively. The mean values of all iris vessel density parameters are shown in Figure 4. The DeBacker Score (n/mm) was 15,2 (±0,45), the proportion of perfused vessel was 94,5% (89,8-99,1%), and the MFI was 3 points (3-3). Taken together, these results indicate that SDF imaging provides a reliable and noninvasive method to examine the iridial microvascular bed in vivo and, thus, may provide unique opportunities for the study of the iridial vascular network in various experimental and clinical settings and disease models.

Abstract 19187: Sublingual Glycocalyx Measurement, a Novel Non-Invasive Technique to Predict Coronary Artery Disease

Background: A relatively thick endothelial lining, known as the glycocalyx (GC), forms the true interface between flowing blood and the vascular wall. The GC regulates several key endothelial functions including vascular permeability, coagulation and inflammation and contributes to the protection against atherogenic challenges. In healthy blood vessels, the GC provides limited access to flowing red blood cells (RBC). Recent observations have suggested that RBCs penetrate deeper into a damaged GC and therefore may serve as a marker for GC damage, which has been associated with microcirculatory dysfunction that accompanies, among others, coronary artery disease (CAD). Aim: In the present study we tested whether the presence of CAD could be predicted by measuring the dimension of the RBC perfused boundary region (PBR), which fills up the space between median RBC column width (MCW) and the outer edge of RBC permeable vascular lumen. In healthy blood vessels PBR is relatively small due to limited penetration of RBC into the GC and it is hypothesized that PBR will increase for a given MCW when GC is damaged. Method: We used sidestream dark field imaging, a novel stroboscopic LED ring-based clinical imaging modality, of the sublingual microvasculature in subjects with (N=10) and without (N=10, controls) angiographic CAD. From these images, MCW and PBR were determined in over 3000 vascular segments (vessel diameter between 10 and 20µm) per subject. Results: CAD patients displayed a significant increase in PBR compared to controls. The mean PBR increased from 2.31 ± 0.09µm to 2.64 ± 0.11µm (P&lt;0.05) comparing controls with CAD patients, respectively, consistent with a 0.3 µm deeper penetration of RBCs into the GC. Conclusion: These data demonstrate that CAD patients have a significant increase in the width of the RBC accessible component of the sublingual microvascular GC compared to control subjects. A wider permeable portion of the GC indicates a change in GC structure which may be associated with a reduced vascular protective function of the GC. Moreover, SDF imaging might provide a novel, noninvasive method to detect CAD.

Evaluation of sublingual microcirculatory blood flow in the critically ill

The microcirculation regulates the supply of oxygen and nutrients to tissues. The sublingual region is frequently used as a window to microcirculation in critically ill patients. Numerous studies have reported impaired sublingual microcirculatory flow. We hypothesized that the quality of sidestream dark field imaging (SDF) recordings could be systematically analyzed to justify the monitoring of sublingual microcirculation in interventional studies or in clinical practice. The sublingual microcirculation in critically ill patients with septic shock, open heart surgery, or alcoholic pancreatitis, and healthy subjects was recorded with a hand held SDF device by one trained investigator in observational setting. A total of 82 video recording sessions were performed and 240 video clips eligible for quality assessment were identified. Quality assessment was performed offline by two investigators independently and blinded for the origin of the video file. Of the 240 clips, pressure artifact was detected in 86 (36%), major blood in 5 (2.1%), major saliva in 21 (8.8%) and extreme brightness causing loss of visible capillaries in 16 (6.7%) clips. The dominating vessel architecture was multiple size vessels in 228 (95%) and repeating capillary loop motif in 12 (5.0%). The mean (± SD) relative size reduction during stabilization was -6.9% (± 4.7%). Excellent technical quality was detected in 74 of 240 (30.8%) recordings. Our findings highlight the need of a comprehensive training period and reporting of data quality before findings with SDF imaging can be accepted as surrogate end points in interventional studies or as guidance in clinical practice.

Withdrawing intra-aortic balloon pump support paradoxically improves microvascular flow

IntroductionThe Intra-Aortic Balloon Pump (IABP) is frequently used to mechanically support the heart. There is evidence that IABP improves microvascular flow during cardiogenic shock but its influence on the human microcirculation in patients deemed ready for discontinuing IABP support has not yet been studied. Therefore we used sidestream dark field imaging (SDF) to test our hypothesis that human microcirculation remains unaltered with or without IABP support in patients clinically ready for discontinuation of mechanical support.MethodsWe studied 15 ICU patients on IABP therapy. Measurements were performed after the clinical decision was made to remove the balloon catheter. We recorded global hemodynamic parameters and performed venous oximetry during maximal IABP support (1:1) and 10 minutes after temporarily stopping the IABP therapy. At both time points, we also recorded video clips of the sublingual microcirculation. From these we determined indices of microvascular perfusion including perfused vessel density (PVD) and microvascular flow index (MFI).ResultsCeasing IABP support lowered mean arterial pressure (74 ± 8 to 71 ± 10 mmHg; P = 0.048) and increased diastolic pressure (43 ± 10 to 53 ± 9 mmHg; P = 0.0002). However, at the level of the microcirculation we found an increase of PVD of small vessels <20 μm (5.47 ± 1.76 to 6.63 ± 1.90; P = 0.0039). PVD for vessels >20 μm and MFI for both small and large vessels were unaltered. During the procedure global oxygenation parameters (ScvO2/SvO2) remained unchanged.ConclusionsIn patients deemed ready for discontinuing IABP support according to current practice, SDF imaging showed an increase of microcirculatory flow of small vessels after ceasing IABP therapy. This observation may indicate that IABP impairs microvascular perfusion in recovered patients, although this warrants confirmation.

SDF Imaging for Assessing Effects of Chemotherapy on Oral Microcirculation

SDF Imaging for Assessing Effects of Chemotherapy on Oral Microcirculation

Changes in the volume status of haemodialysis patients are reflected in sublingual microvascular perfusion

After the introduction of sidestream darkfield imaging (SDF) of the microcirculation, it has become clear that in sepsis, microcirculatory alterations can exist in the absence of systemic haemodynamic abnormalities. However, it is unclear whether this phenomenon also occurs in the treatment of end-stage kidney disease (ESKD) where alterations in the volume status of patients occur during dialysis. We tested the hypothesis that volume changes during dialysis directly affect the perfusion of the microcirculation in a group of adult haemodialysis patients. Secondly, we evaluated microcirculatory response to autotransfusion using the Trendelenburg position (TP). Patients who were on chronic intermittent haemodialysis were assessed for sublingual microvascular flow by SDF imaging pre- and post-TP, performed before and after ultrafiltration (UF). Sublingual microvascular flow was estimated using a semi-quantitative microvascular flow index (MFI) in small (diameter <25 microm, which includes capillaries), medium (25-50 microm) and large-sized (50-100 microm) microvessels (no flow: 0, intermittent flow: 1, sluggish flow: 2 and continuous flow: 3). Changes were evaluated with the non-parametric paired Wilcoxon test. P < 0.05 was judged to indicate a significant difference. Thirty-nine adult patients took part in the study. The underlying diseases causing ESKD were predominantly hypertension (HT, n = 10), diabetes mellitus (DM, n = 7) or both (n = 3). At the start of UF, microvascular flow did not change significantly by TP. After completion of UF, MFI had decreased significantly in all types of microvessels (P < 0.001). After UF (median volume extraction 2.49l), MFI was lower than that at the start of UF and increased in most patients after TP (P < 0.001) in all categories of vessels. Changes were most prominent in the smallest microvessels. Sublingual microvascular perfusion is reduced by UF and can be restored temporarily using autotransfusion by TP due to increased venous return. SDF imaging is able to detect these volume changes. SDF imaging and TP could become a useful bedside tool to evaluate the patient's (microvascular) volume status and response to therapy in dialysis or intradialytic hypotension.

A method for improvement of data quality from OPS/SDF devices in visualization of the microcirculation

OPS imaging (Cytometrics, Philadelphia, PA, USA) and SDF imaging (MicroVision Medical, Amsterdam, The Netherlands) are valuable tools for visualization and study of the microcirculation. Unfortunately, the widespread current practice of using a (digital) video recorder and subsequent transfer to a computer results in data loss. This is due to video compression and nonoptimal use of the available dynamic range. In order to be able to develop and use software for automated data analysis we should strive for the highest possible image quality. Here we describe a simple and cost-effective method for obtaining significant improvement of data quality.