Sidestream dark field imaging and biomarker evaluation reveal minimal significant changes to the microcirculation and glycocalyx in a canine hemorrhagic shock model.

OBJECTIVE: To investigate the effects of hemorrhagic shock and fresh whole blood resuscitation on the microcirculation and endothelial glycocalyx using sidestream dark field (SDF) imaging and plasma biomarkers. ANIMALS: 8 purpose-bred dogs. METHODS: Pressure-targeted hemorrhagic shock was induced in anesthetized dogs. SDF measurement of perfused boundary region and microcirculatory variables (RBC flow, total vessel density, and relative and absolute capillary blood volume), biomarker measurement (heparan sulfate, hyaluronan, VE-cadherin, and syndecan-1), mean arterial blood pressure, and cardiac output measurement were performed before anesthesia (TP0), after induction (TP1), after hemorrhagic shock (TP2), and after 50% retransfusion (TP3) and 100% retransfusion (TP4). RESULTS: At TP1, TP2, TP3, and TP4, mean arterial blood pressure was 74.25 ± 7.17 mm Hg, 49.50 ± 13.74 mm Hg, 63.50 ± 13.29 mm Hg, and 71.38 ± 8.77 mm Hg, and cardiac output was 2.57 ± 1.01 L/min, 0.8 ± 0.36 L/min, 1.81 ± 0.57 L/min, and 2.93 ± 1.22 L/min, respectively. Heparan sulfate, hyaluronan, syndecan-1, and VE-cadherin ranges were 24.80 to 77.72 ng/mL, 5.77 to 105.06 ng/mL, below detection to 1,545.69 pg/mL, and 0 to 2.52 ng/mL, respectively. Perfused boundary region, RBC flow, total vessel density, and relative and absolute capillary blood volume ranges were 1.75 to 2.68 µm, 89.6 to 584.5 µm/s, 51.7 to 1,914.3 mm/m2, 0.94 to 1.53 103 µm3, and 1.50 to 94.30 103 µm3, respectively. Heparan sulfate decreased significantly over time (P = .016). No significant differences were found for microcirculatory variables, perfused boundary regions, or other biomarkers. CLINICAL RELEVANCE: This was the first study to assess microvascular dysfunction and endothelial shedding in a canine hemorrhagic shock model using SDF microscopy (Glycocheck) and plasma biomarkers. Further studies are needed to determine clinical relevance.

Intraoperative intravenous infusion of lidocaine increases total and small vessel densities of sublingual microcirculation: a randomized prospective pilot study.

OBJECTIVE: Multiple organ failure can occur as a result of postoperative complications. Research has indicated that the underlying mechanism of organ dysfunction is a microcirculation disorder. Because of its antioxidant and anti-inflammatory properties, lidocaine has the potential to improve microvascular blood flow. This study was performed to assess the effect of intraoperative intravenous lidocaine infusion on the microcirculation and determine the incidence of postoperative complications. METHODS: In this prospective randomized double-blind pilot study, 12 patients scheduled for abdominal surgery were randomly allocated to receive an intraoperative infusion of either 1% lidocaine or the same volume of 0.9% sodium chloride solution. The microcirculation was monitored using sidestream dark-field imaging and the vascular occlusion test combined with near-infrared spectroscopy. RESULTS: Lidocaine significantly increased the total vascular density and small vessel density after 2 hours of infusion, with preservation of 99% to 100% of the capillary perfusion in both groups. No patients developed organ failure. CONCLUSIONS: An increase in vessel density may be beneficial in major abdominal surgeries because it is associated with better tissue perfusion and oxygen delivery. However, this finding requires further investigation in patients with increased surgical risk. Overall, this study indicates that lidocaine has potential to improve microvascular perfusion.Research Registry number: 9549 (https://www.researchregistry.com/browse-the-registry#home/registrationdetails/650ffd27b3f547002bd7635f/).

Sublingual microcirculation in healthy pediatric population using the sidestream dark-field imaging method.

BACKGROUND: The sidestream dark-field imaging method is used to study microcirculation. Normal values of sublingual microcirculation parameters in healthy children of different age and gender categories are unknown. OBJECTIVE: The study's main goal was to determine normal values of selected parameters of sublingual microcirculation in healthy children of different age and gender categories. METHODS: 40 healthy children were measured, ten aged 3-5.9 years, ten aged 6-10.9 years, ten aged 11-14.9 years, and ten aged 15-18.9 years. After recording the basic anthropometric parameters and vital functions, each volunteer had their microcirculation measured using an SDF probe placed sublingually. Three video clips were recorded and processed offline, and the three best and most stable parts of each were analyzed. RESULTS: Total vascular density, small vessel density, proportion of perfused small vessels, perfused vessel density, perfused small vessel density, and DeBacker's score were significantly higher in females than in males. There were no differences between age groups in microcirculation parameters except MFI. CONCLUSIONS: Age does not influence normal values of microcirculatory parameters. Female gender was associated with higher vessel density, perfused vessel density, and DeBacker's score. A suggestion of the normal range of microcirculatory parameters in healthy children is provided.

Real-time semi-quantitative assessment of anastomotic blood perfusion in mini­invasive rectal resections by Sidestream Dark Field (SDF) imaging technology: a prospective in vivo pilot study.

PURPOSE: Anastomotic leakage (AL) is one of the severe complications after rectal surgery, and anastomotic ischemia is one of the main factors. This prospective in vivo pilot study aimed to evaluate the effectiveness of Sidestream Dark Field (SDF) imaging in quantitative assessment of anastomotic microcirculation and to analyze its correlation with AL. METHODS: Thirty-three patients with rectal cancer who underwent laparoscopic low anterior resection from 2019 to 2020 were enrolled. Microcirculation was measured by SDF imaging at the descending colon, the mesocolon transection line (MTL), and 1 cm and 2 cm distal to the MTL. Anastomotic microcirculation was measured at the stapler anvil edge before anastomosis. Quantitative perfusion-related parameters were as follows: microcirculation flow index (MFI), perfused vessel density (PVD), proportion of perfused vessels (PPV), and total vessel density (TVD). RESULTS: All patients obtained stable microcirculation images. Functional microcirculation parameters (MFI, PPV, PVD) decreased successively from the descending colon, the colon at MTL, and 1 cm and 2 cm distal to the MTL (all P < 0.01). Extremely poor microcirculation was found at the intestinal segment 2 cm distal to the MTL. Micro-perfusion was significantly lower at the colonic limb of the anastomosis compared with the descending colon (all P < 0.001). Anastomotic leakage occurred in 3 patients (9.1%) whose anastomotic microcirculation was significantly lower than those without AL (all P < 0.01). Blood perfusion at the colonic limb of the anastomosis was significantly higher in patients with left colic artery preservation than in controls. CONCLUSION: SDF imaging is a promising technique for evaluating anastomotic microcirculation and has potential clinical significance for risk stratification of AL.

Sublingual Microcirculation Specificity of Sickle Cell Patients: Morphology of the Microvascular Bed, Blood Rheology, and Local Hemodynamics.

Patients with sickle cell disease (SCD) have poorly deformable red blood cells (RBC) that may impede blood flow into microcirculation. Very few studies have been able to directly visualize microcirculation in humans with SCD. Sublingual video microscopy was performed in eight healthy (HbAA genotype) and four sickle cell individuals (HbSS genotype). Their hematocrit, blood viscosity, red blood cell deformability, and aggregation were individually determined through blood sample collections. Their microcirculation morphology (vessel density and diameter) and microcirculation hemodynamics (local velocity, local viscosity, and local red blood cell deformability) were investigated. The De Backer score was higher (15.9 mm-1) in HbSS individuals compared to HbAA individuals (11.1 mm-1). RBC deformability, derived from their local hemodynamic condition, was lower in HbSS individuals compared to HbAA individuals for vessels < 20 µm. Despite the presence of more rigid RBCs in HbSS individuals, their lower hematocrit caused their viscosity to be lower in microcirculation compared to that of HbAA individuals. The shear stress for all the vessel diameters was not different between HbSS and HbAA individuals. The local velocity and shear rates tended to be higher in HbSS individuals than in HbAA individuals, notably so in the smallest vessels, which could limit RBC entrapment into microcirculation. Our study offered a novel approach to studying the pathophysiological mechanisms of SCD with new biological/physiological markers that could be useful for characterizing the disease activity.

Evaluation of the impact of blood donation on tissue perfusion and sublingual microcirculation in dogs: A pilot study.

The objective was to assess the feasibility of the sublingual microcirculation evaluation in dogs by using Sidestream Dark Field (SDF) imaging device and to evaluate the impact of blood donation on sublingual microcirculation and tissue perfusion. Before and after blood sampling, macrocirculatory parameters and tissue perfusion parameters were collected. After quality assessment, four videos per individual and per period were retained for analysis. Data were presented as median (1st quartile - 3rd quartile). The evaluation of the sublingual microcirculation with SDF was feasible in sedated dogs: good quality videos could be recorded in 10/12 dogs (83%). The median blood donation volume was 14 mL/kg (13-15). A significant association between the volume of blood collected and the increase in heart rate was observed: for each milliliter of blood drawn, heart rate increased by 1 bpm (CI95% = [0.2, 2], P = 0.03). Blood collection was associated with a significant increase of shock index (estimate = 0.17, CI95% = [0.02, 0.32], P = 0.04). After blood donation, lactate concentration significantly decreased (before: 2.1 (1.7-2.8), after: 1.1 (0.8-1.7) mmol/l, P = 0.009). No significant variation of the microcirculatory parameters was observed. In conclusion, sublingual evaluation of the microcirculation with SDF technology is feasible in dogs. In the present condition, blood donation did not significantly alter microcirculation. These results need to be confirmed in a larger population.

Intraoperative cerebral blood flow monitoring in neurosurgery: A review of contemporary technologies and emerging perspectives.

Intraoperative monitoring of cerebral blood flow (CBF) has become an invaluable adjunct to vascular and oncological neurosurgery, reducing the risk of postoperative morbidity and mortality. Several technologies have been developed during the last two decades, including laser-based techniques, videomicroscopy, intraoperative MRI, indocyanine green angiography, and thermography. Although these technologies have been thoroughly studied and clinically applied outside the operative room, current practice lacks an optimal technology that perfectly fits the workflow within the neurosurgical operative room. The different available technologies have specific strengths but suffer several drawbacks, mainly including limited spatial and/or temporal resolution. An optimal CBF monitoring technology should meet particular criteria for intraoperative use: excellent spatial and temporal resolution, integration in the operative workflow, real-time quantitative monitoring, ease of use, and non-contact technique. We here review the main contemporary technologies for intraoperative CBF monitoring and their current and potential future applications in neurosurgery.

Non-invasive techniques to access in vivo the skin microcirculation in patients.

The microcirculation is composed of blood vessels with mean internal diameter smaller than 100 µm. This structure is responsible for survival of cells and in the last 50 years its study has become increasingly interesting because it often participates in the pathophysiology of several diseases or can determine better or worse prognosis for them. Due to the growing importance of knowing more about the microcirculation, several techniques have been developed and now it is possible to study its structure or function. In the last 25 years, the cutaneous microcirculation has emerged as an accessible and representative portion of generalized vascular bed allowing the examination of mechanisms of microcirculatory function and dysfunction. This mini review presents several techniques used for non-invasive access to skin microcirculation, such as Nailfold Videocapillaroscopy, Orthogonal Polarization Spectral Imaging, Sidestream Dark Field Imaging, Incident Dark field Illumination, Laser Doppler Flowmetry, and Laser Speckle Contrast Imaging applied. The techniques presented will describe which types of variables (structural or functional) can be evaluated, their limitations and potential uses.

Real-time visualization of renal microperfusion using laser speckle contrast imaging.

SIGNIFICANCE: Intraoperative parameters of renal cortical microperfusion (RCM) have been associated with postoperative ischemia/reperfusion injury. Laser speckle contrast imaging (LSCI) could provide valuable information in this regard with the advantage over the current standard of care of being a non-contact and full-field imaging technique. AIM: Our study aims to validate the use of LSCI for the visualization of RCM on ex vivo perfused human-sized porcine kidneys in various models of hemodynamic changes. APPROACH: A comparison was made between three renal perfusion measures: LSCI, the total arterial renal blood flow (RBF), and sidestream dark-field (SDF) imaging in different settings of ischemia/reperfusion. RESULTS: LSCI showed a good correlation with RBF for the reperfusion experiment (0.94 ± 0.02; p < 0.0001) and short- and long-lasting local ischemia (0.90 ± 0.03; p < 0.0001 and 0.81 ± 0.08; p < 0.0001, respectively). The correlation decreased for low flow situations due to RBF redistribution. The correlation between LSCI and SDF (0.81 ± 0.10; p < 0.0001) showed superiority over RBF (0.54 ± 0.22; p < 0.0001). CONCLUSIONS: LSCI is capable of imaging RCM with high spatial and temporal resolutions. It can instantaneously detect local perfusion deficits, which is not possible with the current standard of care. Further development of LSCI in transplant surgery could help with clinical decision making.

Alterations of cerebral microcirculation in peritumoral edema: feasibility of in vivo sidestream dark-field imaging in intracranial meningiomas.

BACKGROUND: Intracranial meningiomas display a variable amount of peritumoral brain edema (PTBE), which can significantly impact perioperative morbidity. The role of microcirculatory disturbances in the pathogenesis of PTBE is still debated. The aim of this study was to microscopically demonstrate and intraoperatively quantify, for the first time, the alterations to microcirculation in PTBE using sidestream dark-field (SDF) imaging. METHODS: Adult patients with WHO grade I meningiomas were recruited over a 9-month period and divided into 2 groups depending on the absence (NE group) or the presence (E group) of PTBE. In vivo intraoperative microcirculation imaging was performed in the peritumoral area before and after microsurgical resection. RESULTS: Six patients were included in the NE group and 6 in the E group. At the baseline in the NE group, there was a minor decrease in microcirculatory parameters compared to normal reference values, which was probably due to the mass effect. In contrast, microcirculatory parameters in the E group were significantly altered, affecting both vessel density and blood flow values, with a drop of approximately 50% of normal values. Surgical resection resulted in a quasi-normalization of microcirculation parameters in the NE group, whereas in the E group, even if all parameters statistically significantly improved, post-resection values remained considerably inferior to those of the normal reference pattern. CONCLUSION: Our study confirmed significant alterations of microcirculatory parameters in PTBE in meningiomas. Further in vivo SDF imaging studies may explore the possible correlation between the severity of these microcirculatory alterations and the postoperative neurological outcome.

Outcome of a rabbit model for late irradiation effects in mandibular oral mucosa and bone: A pilot study.

BACKGROUND/AIM/OBJECTIVE: Late side effects of radiotherapy (RT) in the treatment for head and neck (HN) malignancies involve an inadequate healing response of the distressed tissue due to RT-induced hypovascularity. The aim of this study was to develop a pilot model in which vascular alterations associated with the onset of late irradiation (IR) injury could be measured in rabbit oral mucosa and mandibular bone. MATERIALS AND METHODS: Eight male New Zealand white rabbits were divided over four treatment groups. Group I-III received four fractions of RT (5.6 Gy, 6.5 Gy, and 8 Gy, respectively) and Group IV received 1 fraction of 30 Gy. Oral microcirculatory measurements were performed at baseline (before RT) and once a week during 11 consecutive weeks after RT assessing perfusion parameters, that is, total vessel density (TVD), perfused vessel density (PVD), proportion of perfused vessels (PPV), and microvascular flow index (MFI). Post-mortem histopathology specimens were analyzed. RESULTS: Five weeks after RT, TVD, and PVD in all groups showed a decrease of >10% compared to baseline, a significant difference was observed for Groups I, II, and IV (P<0.05). At T11, no lasting effect of decreased vessel density was observed. PPV and MFI remained unaltered at all-time points. Group IV showed a marked difference in scattered telangiectasia such as microangiopathies, histological necrosis, and loss of vasculature. CONCLUSION: No significant lasting effect in mucosal microcirculation density due to IR damage was detected. Observed changes in microcirculation vasculature and histology may align preliminary tissue transition towards clinical pathology in a very early state associated with late IR injury in the oral compartment. RELEVANCE FOR PATIENTS: Enhancing knowledge on the onset of late vascular IR injury in the HN region could help the development, monitoring, and timing of therapies that act on prevention, discontinuation, or repair of radiation pathology.

Microcirculation: Physiology, Pathophysiology, and Clinical Application.

This paper briefly reviews the physiological components of the microcirculation, focusing on its function in homeostasis and its central function in the realization of oxygen transport to tissue cells. Its pivotal role in the understanding of circulatory compromise in states of shock and renal compromise is discussed. Our introduction of hand-held vital microscopes (HVM) to clinical medicine has revealed the importance of the microcirculation as a central target organ in states of critical illness and inadequate response to therapy. Technical and methodological developments have been made in hardware and in software including our recent introduction and validation of automatic analysis software called MicroTools, which now allows point-of-care use of HVM imaging at the bedside for instant availability of functional microcirculatory parameters needed for microcirculatory targeted resuscitation procedures to be a reality.

Possible Impact of Spinal Anesthesia and Phenylephrine on Sublingual Microcirculation of Cesarean Delivery Patients.

BACKGROUND: This study was a proof of concept of a novel means to evaluate microcirculatory changes during spinal anesthesia for cesarean delivery. It sought to examine the distributive circulatory effects of spinal anesthesia and evaluate the impact of phenylephrine administration on the microcirculation of these women. METHODS: After Research Ethics Board approval, healthy, non-laboring pregnant women with singleton, term pregnancies scheduled for elective cesarean delivery were recruited. Participants were randomly assigned to receive either phenylephrine infusion or phenylephrine bolus. Spinal anesthesia was standardized. A sidestream dark-field (SDF) MicroScan® video microscope was applied to the sublingual mucosa to obtain microcirculation videos in five different visual fields. Videos were made before and after spinal anesthesia. The resultant videos were analyzed randomly and blindly. The mean microvascular flow index (MFI) values were compared before and after spinal anesthesia. The difference in MFI following spinal anesthesia was compared between phenylephrine infusion and bolus groups. RESULTS: Thirty-two patients were recruited for the study; 22 patients had complete video sets for analysis. Baseline characteristics were similar between the two groups, including preoperative hemodynamics. There were no significant differences between pre- and post-spinal MFI. The post-spinal MFI within the infusion group (mean ± standard deviation: 2.74 ± 0.21) was not significantly different from the bolus group (2.56 ± 0.42, P = 0.22). CONCLUSION: Despite theoretical physiological implications of spinal anesthesia and phenylephrine on the microcirculation, significant alteration of the MFI was not observed between pre- and post-spinal anesthesia (within group). Additionally, despite an eight-fold larger phenylephrine dose for continuous infusion prophylaxis used in this group of women, this did not result in a significant alteration of the microcirculation compared to those who received phenylephrine treatment for hypotension (between groups).

Microcirculatory Differences in Children With Congenital Heart Disease According to Cyanosis and Age.

Background: Congenital heart disease (CHD) is one of the main causes of morbidity and mortality in children. Microcirculatory changes in CHD patients have previously been investigated using a variety of techniques. Handheld videomicroscopy enables non-invasive direct visualization of the microcirculatory bed. The aim of our study was to determine if there are microcirculatory differences among CHD patients based on age and the presence of cyanosis. Methods: A prospective observational study was carried out. Patients with CHD undergoing corrective surgery were evaluated after anesthetic induction prior to surgery. Microcirculation was evaluated using sidestream dark field (SDF) imaging. Hemodynamics and respiratory, biochemical, and tissue perfusion parameters were analyzed. Results: A total of 30 patients were included, of whom 14 were classified as cyanotic and 16 as non-cyanotic. Cyanotic patients had a higher total vessel density (TVD) (p = 0.016), small vessel density (p = 0.004), and perfused small vessel density (p = 0.013), while their microvascular flow index (MFI) was lower (p = 0.013). After adjustment for age and PaO2, cyanotic patients showed increased TVD (p = 0.023), and small vessel density (p = 0.025) compared to non-cyanotic patients but there were no differences on the MFI. Age was directly correlated with total MFI (spearman's rho = 0.499, p = 0.005) and small vessel MFI (spearman's rho = 0.420, p = 0.021). After adjustment for the type of CHD (cyanotic vs. non-cyanotic) patients with MFI and small MFI vessels <3 were younger than those with values ≥3 (p = 0.033 and p = 0.037). Conclusions: SDF-based evaluation of microcirculation in CHD patients showed that patients with cyanotic defects had higher vascular density, as compared to patients with non-cyanotic defects. Younger patients were more likely to have a low MFI regardless of their type of CHD.

Sidestream Dark Field (SDF) imaging of oral microcirculation in the assessment of systemic sclerosis.

INTRODUCTION: Systemic sclerosis (SSc) is a systemic disease characterised by abnormalities in small blood vessels, skin and organ fibrosis. It is assessed using generalised skin thickening scores, autoantibodies and nailfold capillaroscopy. Sidestream Dark Field imaging (SDF) is a non-invasive imaging tool that assesses microcirculation. This study aims to investigate the potential of using SDF as a diagnostic tool in SSc. METHOD: Oral microcirculation of 20 patients with SSc was compared to 20 age and gender matched controls using SDF imaging. Sublingual, buccal and incisor regions of the mouth were examined. All volunteers were female averaging 48.0 (24-64) years old. Vasculature was assessed by calculating the De Backer score and Functional Capillary Density (FCD) on an imaging software. RESULTS: At all regions of the mouth, SSc patients had a significantly lower De Backer score compared to controls (SSc 3.484 ±â€¯0.1361/mm vs Control 5.184 ±â€¯0.1896/mm, unpaired t-test p < 0.0001). The SSc patients showed significantly lower FCDs compared to controls at all areas as well (SSc 19.65 ±â€¯0.9445% vs Control 29.45 ±â€¯1.681%, unpaired t-test, p < 0.0001). The incisor regions had significantly higher De Backer and FCD scores than buccal and sublingual regions in both control and SSc patients (one way anova, p < 0.05). De Backer/FCD scores showed significant correlation against Rodnan Skin Scores in patients with SSc (Pearson correlation, p < 0.05). CONCLUSIONS: SSc patients showed decreased oral vasculature compared to controls. SDF imaging has shown the ability to be a useful diagnostic tool in the assessment of SSc.

Two-wavelength oximetry of tissue microcirculation based on sidestream dark-field imaging.

Monitoring oxygen saturation (SO2) in microcirculation is effective for understanding disease dynamics. We have developed an SO2 estimation method, sidestream dark-field (SDF) oximetry, based on SDF imaging. SDF imaging is a noninvasive and clinically applicable technique to observe microcirculation. We report the first in vivo experiment observing the changes in SO2 of microcirculation using SDF oximetry. First, heat from the light-emitting diodes used for the SDF imaging might affect hemodynamics in microcirculation, hence, we performed an experiment to evaluate the influence of that on the SDF oximetry. The result suggested that SDF oximetry had enough stability for long-term experiments. Then, to evaluate the sensitivity of SDF oximetry to alterations in the hemodynamics of the microcirculation, we observed the time-lapsed SO2 changes in the dermis microcirculation of rats under hypoxic stimulation. We confirmed that the SO2 estimated by SDF oximetry was in accordance with changes in the fraction of inspired oxygen (FiO2). Thus, SDF oximetry is considered to be able to observe SO2 changes that occur in accordance with alteration of the microcirculation.

Impact of microcirculatory video quality on the evaluation of sublingual microcirculation in critically ill patients.

We aimed to assess the impact of image quality on microcirculatory evaluation with sidestream dark-field (SDF) videomicroscopy in critically ill patients and explore factors associated with low video quality. This was a retrospective analysis of a single-centre prospective observational study. Videos of the sublingual microcirculation were recorded using SDF videomicroscopy in 100 adult patients within 12 h from admittance to the intensive care unit and every 24 h until discharge/death. Parameters of vessel density and perfusion were calculated offline for small vessels. For all videos, a quality score (-12 = unacceptable, 1 = suboptimal, 2 = optimal) was assigned for brightness, focus, content, stability, pressure and duration. Videos with a total score ≤8 were deemed as unacceptable. A total of 2455 videos (853 triplets) was analysed. Quality was acceptable in 56 % of videos. Lower quality was associated with worse microvascular density and perfusion. Unreliable triplets (≥1 unacceptable or missing video, 65 % of total) showed lower vessel density, worse perfusion and higher flow heterogeneity as compared to reliable triplets (p < 0.001). Quality was higher among triplets collected by an extensively-experienced investigator or in patients receiving sedation or mechanical ventilation. Perfused vessel density was higher in patients with Glasgow Coma Scale (GCS) ≤8 (18.9 ± 4.5 vs. 17.0 ± 3.9 mm/mm2 in those with GCS >8, p < 0.001) or requiring mechanical ventilation (18.0 ± 4.5 vs. 17.2 ± 3.8 mm/mm2 in not mechanically ventilated patients, p = 0.059). We concluded that SDF video quality depends on both the operator's experience and patient's cooperation. Low-quality videos may produce spurious data, leading to an overestimation of microvascular alterations.

Changes of small intestine villus and sublingual microcirculation in rabbits during endotoxic shock observed by sidestream dark-field imaging / 中国病理生理杂志

AIM: To investigate the changes of small intestine villus and sublingual microcirculation perfusion in the rabbits during endotoxic shock by sidestream dark-field imaging (SDF) after resuscitation to a mean arterial pressure (MAP) level.METHODS: New Zealand white rabbits (n=60) were randomly divided into 2 groups (group of villus and group of sublingua).The fistula operation of ileum was performed.Lipopolysaccharide was injected to establish endotoxic shock model, and fluid resuscitation (lactated Ringer's solution, 30 mL·kg-1·h-1) was given to maitain the MAP of the animals to 80 mmHg.Continuous norepinephrine was intravenously injected at 0.5~1 μg·kg-1·min-1 only if fluid therapy did not maintain the MAP level.The changes of microcirculatory perfusion indexes in small intestine villus and sublingual tissues such as vessels per villus (VV), microvascular flow index (MFI), proportion of perfused villi (PPVi), villus border score, villus vessel score, total vessel density (TVD), perfused vessel density (PVD) and proportion of perfused vessels (PPVe) were continuously observed and recorded by SDF before shock, during shock and after fluid resuscitation.RESULTS: MFI and PPVi in small intestine villus, and MFI, PPVe, TVD and PVD in sublingual tissues were significantly decreased after shock (P<0.01).Compared with MFI in sublingual microcirculation, MFI in villus was significantly decreased (P<0.01).MFI and PPVi in small intestine villus, and MFI, PPVe, TVD and PVD in sublingual tissues were improved after recovered to the target MAP by fluid resuscitation (P<0.05).However, MFI in small intestine villus was significantly lower than that in sublingual tissues after fluid resuscitation (P<0.01).CONCLUSION: The difference between small intestine villus and sublingual microcirculation perfusion during endotoxic shock is observed.The descent degree of microcirculation perfusion in small intestine villus is larger than that in sublingual tissues after shock, and the recovery degree of small intestine villus microcirculation is lower than that of sublingual microcirculation afer fluid resuscitation.

Changes of small intestinal villi microcirculation in sidestream dark-field imaging with different target blood pressure in rabbits during endotoxin shock / 中华危重病急救医学

Objective Changes of small intestine villus microcirculation perfusion in sidestream dark-field (SDF) imaging in the rabbits during endotoxic shock after fluid resuscitation with different target mean arterial pressure (MAP), and evaluation of feasibility of monitoring small intestine villus microcirculation by SDF were studied. Methods Sixty standard New Zealand white rabbits were randomly divided into two groups: low target MAP group (group A, n = 30) and high target MAP group (group B,n = 30). Fistula operation of ileum was madein vitro, and lipopolysaccharide (LPS, 2 mg/kg) was injected to establish endotoxic shock model. Group A was administered with the lower dose fluid resuscitation (lactated Ringer solution, 20 mL·kg-1·h-1) for target MAP of 65 mmHg (1 mmHg =0.133 kPa); group B was administered with the higher dose fluid resuscitation (lactated Ringer solution, 30 mL·kg-1·h-1) for MAP of 80 mmHg. Continuous norepinephrine intravenous injection (0.5-1.0μg·kg-1·min-1) was administered only after fluid therapy couldn't reach the target MAP. The changes of small intestine villus microcirculation perfusion indexes such as vessels per villus (VV), proportion of perfused villi (PPV), microvascular flow index (MFI), borders of villus score (BVS), vessels villus score (VVS) were continuously observed and recorded before the shock, during the shock and after fluid resuscitation using SDF imaging. The differences of microcirculation perfusion were compared between two groups using the specific parameter evaluation system to determine severity of villi microcirculation and injury scores at different stages.Results VV and borders of villus were clear and contact before shock in two groups. After shock, VV, PPV were significantly decreased in both two groups, the borders of villus were destroyed, MFI, BVS, VVS and the total score of villi injury microcirculation were obviously and severely decreased. Partial blood flow of villous capillaries after fluid resuscitation was recovered in two groups, but the perfusion of some region was un-balanced with the outworn borders of villus. VV were rose as compared before and after fluid resuscitation in groups A and B (vessels: 1.21±0.22 vs. 0.81±0.12, 1.54±0.28 vs. 0.79±0.13), and PPV [(31±4)% vs. (12±2)%, (38±5)% vs. (13±3)%], MFI (1.55±0.09 vs. 1.09±0.03, 1.97±0.11 vs. 1.05±0.03), VVS (points: 1.22±0.08 vs. 0.89±0.02, 2.06±0.15 vs. 0.90±0.02) and the sum of MFI, BVS, VVS (3.70±0.19 vs. 2.85±0.07, 5.01±0.29 vs. 2.88±0.08) were significant rose (allP 0.05).Conclusions For the small intestine villus microcirculation perfusion, the higher target MAP (80 mmHg) after fluid resuscitation or/and vasoconstrictor drugs usage were probably better than the relatively lower target MAP (65 mmHg) during endotoxic shock. SDF imaging is a very promising technique for intestinal villi microcirculatory visualization and assessment.

Microcirculatory blood flow during cardiac arrest and cardiopulmonary resuscitation does not correlate with global hemodynamics: an experimental study.

BACKGROUND: Current research highlights the role of microcirculatory disorders in post-cardiac arrest patients. Affected microcirculation shows not only dissociation from systemic hemodynamics but also strong connection to outcome of these patients. However, only few studies evaluated microcirculation directly during cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). The aim of our experimental study in a porcine model was to describe sublingual microcirculatory changes during CA and CPR using recent videomicroscopic technology and provide a comparison to parameters of global hemodynamics. METHODS: Cardiac arrest was induced in 18 female pigs (50 ± 3 kg). After 3 min without treatment, 5 min of mechanical CPR followed. Continuous hemodynamic monitoring including systemic blood pressure and carotid blood flow was performed and blood lactate was measured at the end of baseline and CPR. Sublingual microcirculation was assessed by the Sidestream Dark Field (SDF) technology during baseline, CA and CPR. Following microcirculatory parameters were assessed off-line separately for capillaries (≤20 µm) and other vessels: total and perfused vessel density (TVD, PVD), proportion of perfused vessels (PPV), microvascular flow index (MFI) and heterogeneity index (HI). RESULTS: In comparison to baseline the CA small vessel microcirculation was only partially preserved: TVD 15.64 (13.59-18.48) significantly decreased to 12.51 (10.57-13.98) mm/mm(2), PVD 15.57 (13.56-17.80) to 5.53 (4.17-6.60) mm/mm(2), PPV 99.64 (98.05-100.00) to 38.97 (27.60-46.29) %, MFI 3.00 (3.00-3.08) to 1.29 (1.08-1.58) and HI increased from 0.08 (0.00-0.23) to 1.5 (0.71-2.00), p = 0.0003 for TVD and <0.0001 for others, respectively. Microcirculation during ongoing CPR in small vessels reached 59-85 % of the baseline values: TVD 13.33 (12.11-15.11) mm/mm(2), PVD 9.34 (7.34-11.52) mm/mm(2), PPV 72.34 (54.31-87.87) %, MFI 2.04 (1.58-2.42), HI 0.65 (0.41-1.07). The correlation between microcirculation and global hemodynamic parameters as well as to lactate was only weak to moderate (i.e. Spearman's ρ 0.02-0.51) and after adjustment for multiple correlations it was non-significant. CONCLUSIONS: Sublingual microcirculatory parameters did not correlate with global hemodynamic parameters during simulated porcine model of CA and CPR. SDF imaging provides additional information about tissue perfusion in the course of CPR.