The Sidestream Dark Field (SDF) Handheld Imaging Device

(visualize the microcirculation at the bedside, Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation, Microvascular (blood) image observation instrument,Sidestream Dark Field(SDF),sidestream dark field imaging (SDF))

      The microvessel (blood) image observation instrument(Sidestream Dark Field (SDF) Handheld Imaging Device ) use SDF technology, observe the special parts of the animal or human blood flow changes.
The condition of the blood vessels and blood of experimental animals can provide for the animal experiments, in order to cardiovascular disease in experimental animals blood poisoning、sepsis and failure early noninvasive monitoring and scientific data, and provide scientific data for the human disease.
Its technical characteristics are as follows:
(1) Use SDF technology, can observe animal or person special parts such as the tongue, kidney and other parts of the blood flow changes.
(2)can provide the number of capillaries, vascular caliber and velocity, TVD / PVD, PPV, / MFI of experimental animals of data , and so on .
(3) equipment with convenience, can be carried out directly noninvasive observed in the laboratory experiments bedside characteristics, operation is simple.

Imaging of the sublingual microcirculation in elderly patients – a pilot study
Islam Saleh Abdo1,2, Zdenek Turek2, Renata Parizkova2, Vladimir Cerny1,2
1 Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie
University, Halifax, Nova Scotia, Canada 2 Department of Anesthesia and Intensive Care Medicine, University Hospital Hradec
Kralove, Faculty of Medicine Hradec Kralove, Charles University in Prague, Czech Republic

Abstract
Demographic changes, i. e. worldwide increase in older population, require to direct research ef¬forts to age-relevant topics. The present article focuses on microcirculation in elderly patients. Sidestream dark field (SDF) imaging(visualize the microcirculation at the bedside, Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation, Sublingual microcirculation), a relatively new technology, allows direct visualization of mucos¬al microcirculation and imaging of surface layers of solid organs using a handheld microscopical camera probe. Our study aimed at assessing sublingual microcirculation in elderly patients using this new SDF technology (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) in order to identify and compare changes across different age groups. The study results suggest that even in healthy individuals microvascular flow index (MFI) and functional capillary density (FCD) change significantly during the process of aging.
Key words: microcirculation, sublingual, elderly, Sidestream dark field (SDF) imaging (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation)
Introduction
These changes in the world’s demographics drive focus also of microcirculation（visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation） The last decades witnessed an increase in the research towards elderly patients. An under¬world’s older population, specially in the de-standing of age-dependent adaptation in the veloped countries, this being the result of a structure and function of microvascular net¬more advanced health care, better social sys-works is critical to understanding how deliv¬tems and improved living conditions in de-ery and distribution of blood flow is con¬veloped countries. The U.S. Census Bureau trolled across the life span. released a report in 2009 that showed that sidestream dark field (SDF) imaging(visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) has risen as the world’s 65-and-older population is pro-a pioneer among different technologies dejected to triple by mid century, from 516 mil-signed to image the human microcirculation lion in 2009 to 1.53 billion in 2050. In con-(1-3). This relatively new technology allows trast, the population under 15 is expected to the direct visualization of mucosal microcir¬increase by only 6 percent during the same culation and imaging of surface layers of sol¬period, from 1.83 billion to 1.93 billion. id organs using a handheld microscopical From 2009 to 2050, the world’s 85 and old-camera probe. This technology depends on a er population is projected to increase more light guide imaging the microcirculation, than fivefold, from 40 million to 219 million. which is surrounded by light emitting diodes
at a wavelength of 530nm. The hemoglobin of the erythrocytes absorbs this green light while the rest of the light is scattered to form the white-greyish background. This produces clear images of capillaries with flowing ery¬throcytes (4). SDF (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation)has played a role in min¬imizing the gap in understanding the micro¬circulation and helped move microcirculato¬ry research from bench to bedside.
The primary aim of our study was to study the sublingual microcirculation in eld¬erly patients using SDF technology (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation). To iden¬tify changes in microcirculatory parameters during the physiological process of aging we compared the microcirculation of different age groups (20-39, 40-69, 75-90 years).
Methods
Subject Selection
Approval for the study was granted by the REB of the University Hospital, Hradec Králové, Czech Republic. Written informed consent was obtained from all participants.
We divided the study subjects in three groups, regardless of their sex. The first group (Group A, n=10) included healthy subjects (ages 20-39 years), the second group (Group B, n=10) included 10 healthy subjects (ages 40-69), and the third group (Group C, n= 10) healthy subjects (ages 70¬90).
Since the aim was to study the physiolog¬ical changes during aging, in all groups we included only subjects that were healthy, did not have any chronic diseases and did not take any medications. Furthermore, they were all of good physical condition, with the elderly capable of performing daily activities on their own without the need of assistance. All subjects were of good mental health, with no history of dementia (6), Alzheimers (7), psychosis or behavioral disturbances. All our subjects were non-smokers (8, 9). All subjects had hematocrit values within the normal ranges.
We excluded subjects with any previous history of conditions that could cause patho¬logical changes in the microcirculation(visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation). Our subjects did not have any history of hyper¬tension (12), ischemic heart disease, diabetes mellitus, ischemic diseases of the lower ex¬tremities, cerebrovascular diseases, critically ill patients, subjects undergoing mechanical ventilation or being treated for all forms of circulatory shock (13-16).
All subjects were instructed to refrain from consuming caffeine-containing sub¬stances 2 h prior to the evaluation. No seda¬tion was used during the image recordings and all subjects were cooperative.
Study settings
Image recordings of the microcirculation (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation)took place at two locations. Subjects from group A and B where invited to the library of the Department of Anesthesiology and Inten¬sive Care Medicine, University Hospital of Hradec Králové. Subjects from group C where residents of the Senior Home of Hradec Králové, and to ensure their comfort, the image recordings where taken at site at the in-house clinic. Each subject was exam¬ined individually in the supine position to al¬low comfortable measuring for both the sub¬jects and the examiners, the elderly patients were asked to remove any dental prostheses.
The sublingual microcirculation was vi¬sualized using the MicroScan SDF (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation)camera (MicrovisionMedical, Amsterdam, The Netherlands). In order to facilitate the proce¬dure and minimize artifacts, all images were obtained by two investigators with long¬standing experience in this technique. The SDF (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation)probe was covered with a sterile plastic lens and lightly placed on the target sublin¬gual mucosa, the subjects were asked to hold their mouth in a semi-closed position in or¬der to help positioning the camera. Two trained physicians blinded to clinical data performed measurements. Subjects were in supine position, in a temperature controlled room with a temperature of approximately 22°C. The tip of the SDF (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) probe was placed

on sublingual mucosa. To prevent microcir¬culatory perfusion disturbance due to appli¬cation of pressure on the imaging area, the probe was first placed on the labial tissue and then retracted to an extent, which mini¬mized contact but enabled visualisation of the capillary bed. Illumination intensity and depth of focus were modulated to fine-tune image quality. Continuous digital image recordings (duration 1 min) were captured in five different locations under the tongue, and digital image recordings were saved on a hard drive as DV-AVI files to enable offline analysis. For high quality image recording we followed the recommendations of the round table consensus on image acquisition and analysis (17).
Off-line analysis
SDF (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation)video clips were coded and analysed off line, using the methods described by De Backer et al. (17). Data were analyzed using the AVA3 software (MicrovisionMedical, Amesterdam, The Netherlands). The soft¬ware enables automatic detection of vessels (7 -100 µm) for the calculation of their diam¬eter, length, density and flow. We used the software to calculate Microvascular Flow In¬dex (MFI), and Functional Capillary Density (FCD).
To calculate the MFI, the image was di¬vided into four quadrants. Characteristic flow scores were assigned in each quadrant for each vessel size category. The flow categories are 0 for no flow, 1 for intermittent flow, 2 for sluggish flow and 3 for continuous flow. The flow category as¬signed to each vessel category is then summed for the four quadrants and divided by the number of quadrants in which the ves¬sel type is present (MFI range 0–3).
FCD is defined as the length of red blood cell-perfused capillaries per observation area and is given in cm/cm2. FCD is calculated by applying three equidistant horizontal and three equidistant vertical lines superimposed upon the video sequence. FCD was calculat¬ed as the number of capillaries crossing the
lines divided by their total length. This gave the number of capillaries per mm. FCD for small vessels was estimated in vessels with less than 25 µm in diameter.
Statistical analysis
Statistical analysis was performed using Prism 4 (GraphPad, La Jolla, CA, USA). All data were analyzed using a one-way analysis of variance (ANOVA), followed by the Tukey post hoc test. A p value < 0.05 was consid¬ered significant.
Results
Between groups A (20-39) and B (40-69) we did not observe significant differences in the FCD of all vessels, FCD of small vessels or MFI (Figures 1-3). However, significant de¬creases in the FCD of all vessels, FCD of small vessels and MFI was found when com¬paring groups A (20-39) and C (70-90) or B (40-69) and C (70-90), respectively.
Discussion
We found a significant decrease in the mi¬crocirculatory parameters FCD and MFI in group C (70-90) when compared to the oth¬er two groups A (20-39) and B (40-69). In group C the significant decrease in FCD was found in small capillaries (less than 25 µm in diameter) as well in all vessels. The greatest difference was found in the FCD of small vessels.
The dramatic increase in the number of people reaching age 65 – coupled with their increased life expectancy – has expanded the classification of those of age 65 and old¬er to include three sub-populations com¬monly referred to as the „young old” (being the age of 65-74), the „old” (74-84), and the „old-old“ (being older than 85; (5)). To sim¬plify our study design, we divided the sub¬jects into three sub-groups (group A: 20-39, group B: 40-69 and Group C: 70-90 years).

Figure 1: Functional capillary densi-ty (FCD) of all microvessels (<100µm), n=10 per group.* p<0.05 vs. 20-39 and 40-69 yearsold

Figure 2: Functional capillary densi-ty (FCD) of small microvessels (<25µm), n=10 per group.* p<0.05 vs. 20-39 and 40-69 yearsold

Figure 3: Microvascular Flow Index(MFI) of all microvessels (<100 µm),n=10 per group.* p<0.05 vs. 20-39 and 40-69 yearsold
　

All subjects had hematocrit values within the normal ranges. The hematocrit in the prefer¬ential flow channels is an inverse function of the flow rate for any level of the microcircu¬latory hematocrit. The increased hematocrit raises the flow resistance in these vessels which reduces flow further and represents a positive feedback condition which may con¬tribute to the intermittent and uneven flow patterns which are present within the micro¬circulation (10, 11)
Our results concur with previous results from studies that looked at the microcirculatory(visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) changes during the process of aging. Ex¬perimental data indicate that, independent of the presence of other pathologies, aging al¬ters endothelium-dependent relaxations in both the aorta and small resistance arteries in rats (18-21). Brandes et al. (22) suggested that aging is associated with a reduction in the regenerative capacity of the endothelium and endothelial senescence, which is char¬acterized by an increased rate of endothelial cell apoptosis. Muller et al. (23) showed that aging impairs endothelium-dependent va¬sodilation in rat skeletal muscle arterioles.
Taddei et al. (24) evaluated the role of ad¬vancing age as an independent factor that can alter endothelial function. They demon¬strated that the vasodilating response to acetylcholine decreased with advancing age in the forearm of both normotensive control subjects and essential hypertensive patients, whereas the vasodilating response to sodium nitroprusside was minimally affected by ag¬ing. Taken together, these results are consis¬tent with the finding that endothelial func¬tion is progressively impaired with aging (24). In a separate study the same group pro¬posed the age related endothelial dysfunc¬tion to be mediated by a progressive reduc¬tion of NO availability, since the inhibiting effect of L-NMMA on acetylcholine-induced vasodilation was progressively impaired by advancing age (25). Angula et al. (26) showed that although the aging process by it¬self, without other concomitant morbidities, causes an impairment of endothelium-de¬pendent vasodilation of human vessels, the presence of cardiovascular risk factors exac¬erbated such impairment in aged human ves¬sels. Furthermore they suggested that the re¬sponse of aged human vessels to treatments for improving (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) endothelial function might be different from that of vessels from adult sub¬jects (26). Eskurza et al. (27) confirmed that oxidative stress was the main mediator of the age related endothelial dysfunction.
A group of studies focused on evaluating the blood flow in specific muscle groups dur¬ing exercise. Wahren et al. (28) showed that the rise in leg blood flow during exercise was decreased in older male subjects (52–59 years) compared to the values measured in young male subjects (25–30 years). Proctor et al. (29) have also shown that leg blood flow and vascular conductance during sub¬maximal cycling exercise at a given level of whole-body oxygen consumption are sub¬stantially reduced in older men as compared to their young counterparts. Furthermore, muscle blood flow is lower in older human subjects when a small muscle mass is active and the limits of cardiac output are not ap¬proached (30). In conclusion, data obtained in humans indicate that age-induced adapta¬tions of the vasculature contribute to a reduc¬tion in muscle blood flow; however, the spe¬cific mechanisms that contribute to the age¬related diminution of blood flow to muscle have not been discerned in human models (31).
The affect of aging on the density of mi¬crovessels has not been studied in detail yet, and there is no striking consensus on the ef¬fects of aging on capillary density. Hutchins et al. (32) and Sonntag et al. (33) demonstrat¬ed a substantial aging-related rarefaction of the surface arterioles that supply the parenchymal vessels of the cerebral cortex in rats. In normally aging rats, the density of ar¬terioles was almost 40% lower in senescent animals than in young adults (29 months ver¬sus 7 months of age).
SDF(visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) was not previously used for evalua¬tion of the microcirculation (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) in elderly pa¬tients. Previous studies mainly focused on the molecular level to illustrate the age relat¬ed endothelial dysfunction (24-26) or used techniques such as the constant-rate intra-ar¬terial indicator infusion technique to study the changes in blood flow (27, 34). To our knowledge no study has evaluated the capil¬lary density in humans.
Conclusion
We were able to identify in healthy subjects the age group at which the microcirculatory parameters FCD and MFI change significant¬ly. Individuals above the age of 70 years should be excluded from studies evaluating the microcirculation (visualize the microcirculation at the bedside,Cerebral microcirculation,Brain microcirculation,Renal microcirculation,Kidney microcirculation,Sublingual microcirculation) because of the age-relat¬ed changes found in our study. Even though individuals above the age of 70 years could be free from pathological conditions, stan¬dard microcirculatory parameters are altered.
Acknowledgements
Supported by the project (Ministry of Health, Czech Republic) for conceptual develop¬ment of research organization 00179906 and by the programme PRVOUK P37/02.
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