Doppler Probe Research Articles

Periorbital Placement of a Laser Doppler Probe for Cerebral Blood Flow Monitoring Prior to Middle Cerebral Artery Occlusion in Rodent Models.

Middle cerebral artery occlusion (MCAO) is the gold-standard method for preclinical modeling of ischemic stroke in rodents. However, successful occlusion is not guaranteed by even the most skilled surgical hands. Errors primarily occur when the filament is not placed at the correct depth and include instances of either no infarction or vessel perforation, which can cause death. Laser Doppler flowmetry (LDF) is a reliable technique that provides real-time feedback on regional cerebral blood flow (CBF) during the MCAO procedure. Here we demonstrate a rapid technique for periorbital placement of a laser Doppler probe for measurement of CBF in both mice and rats. Our rationale was to simplify LDF implementation, encouraging widespread usage for improved surgical reliability. The technique eliminates the need for skull thinning and specialized equipment, with placement at the periorbital region rather than dorsal placement, promoting efficiency and ease of adoption. The protocol described here encompasses presurgical preparations, periorbital Doppler probe placement, and post-operative care. Representative results include visual depictions of procedural elements along with representative LDF tracings illustrating successful MCAO surgeries, with instances of unsuccessful filament placement leading to complications. The protocol illustrates LDF in confirming proper filament placement and offers a simplified procedure compared to alternative methods.

Clinical application of parasacral artery perforator flap in the treatment of Pilonidal Sinus Diseases

Objective: To investigate clinical efficacy of parasacral perforator flap (PPF) on postoperative wound healing in pilonidal sinus diseases (PSDs). Methods: The surgery steps were as follows: (1) To preoperatively detect parasacral perforator arteries with the handhold Doppler probe and mark them; (2) To remove the infected and necrotic tissues of PSDs completely; (3) To design the PPF according to the wound size and the parasacral perforator arteries' localization; (4) To harvest the flap from the gluteus maximus muscle surface and transfer it to the wound without tension. Several data were documented, including surgical duration, flap length, flap width, drainage tube placement duration, hospital stay, duration from operation to stitch removal, postsurgical complications and recurrence. Results: There were six patients with PSDs whose postoperative wound healing was repaired by PPF, admitted in our department from March 2021 to March 2023. Of them, five were male and one was female. Their median age was 24 (range: 18-33) years old. Their median surgical duration was 165 (range: 134-207) minutes, median length of PPF was 8 (range: 7-11) cm, median width of PPF was 3 (range: 3-4) cm, mean duration of drainage tube placement was 8 (range: 4-17) days, mean hospital stay was 13 (range: 6-23) days, mean duration from operation to stitch removal was 14 (range: 14-17) days, median follow-up time was 6-16 months. Incisions of all six cases achieved first-intention healing without early- or late-stage complications. No recurrence occurred during follow-up. All patients involved were satisfied with their clinical efficacy. Conclusion: The utility of PPF in postoperative wound healing of PPDs was effective, safe and reliable.

A case report of critical aortic stenosis diagnosed utilizing non-imaging continuous wave Doppler probe

Abstract Background Aortic stenosis (AS) is the most commonly acquired valvular pathology in the western world. Aortic stenosis severity is typically evaluated with Doppler echocardiography. Evaluation of aortic gradients using standard Doppler echocardiography from the apical window may underestimate the true gradient due to misalignment of blood flow to the ultrasound beam and is often better evaluated from other imaging windows using a non-imaging continuous wave Doppler (NI-CWD) probe. Herein, we describe a unique case of AS being underestimated by dynamic acoustic shadowing from the apical window rather than beam misalignment. Case summary The patient is a Hispanic 31-year-old male with a congenital bicuspid aortic valve who underwent a balloon aortic valvuloplasty at age 13. At age 31, the patient underwent a repeat transthoracic echocardiogram (TTE) that was largely unchanged from his prior TTE from 15 years prior. Notably on this TTE, there was acoustic shadowing of colour Doppler in the distal left ventricular outflow tract and aortic valve during systole. While gradients only suggested moderate AS, the degree of left ventricular hypertrophy was suspicious for more severe AS. Only by using the NI-CWD probe at the right sternal border were we able to identify very severe AS with a peak velocity of 6.5 m/s and a mean gradient of 100 mmHg. Discussion In our specific case, dynamic acoustic shadowing of the aortic valve from the apical window obscured both imaging and Doppler signals. This acoustic shadowing was not present from the right sternal border with the NI-CWD probe, leading to an over 100% increase in aortic valve peak velocity and proper correction of AS severity. This allowed for expedited care and underscores the importance of such techniques.

V-113.1: Exploring the role of an implantable doppler probe as a blood flow-monitoring device in kidney transplant: A feasibility randomized controlled trial.

V-113.1: Exploring the role of an implantable doppler probe as a blood flow-monitoring device in kidney transplant: A feasibility randomized controlled trial.

P.177: The experiences of participation in a study investigating feasibility of the implantable doppler probe in kidney transplantation: An embedded qualitative study.

P.177: The experiences of participation in a study investigating feasibility of the implantable doppler probe in kidney transplantation: An embedded qualitative study.

Intraoperative Doppler flowmetry evaluation of humeral head perfusion after proximal humerus fracture

Understanding vascularity and assessing the risk of post-traumatic avascular necrosis are crucial for predicting outcomes and identifying optimal treatment options in proximal humerus fractures (PHFs). Until now, Hertel etal have been the only researchers to evaluate the intraoperative perfusion of the humeral head after fracture using Doppler flowmetry in a central single drill hole within the head. This pilot study aims to standardize the evaluation of intraoperative perfusion measurements in different areas of the humeral head in patients with PHF. In this prospective pilot study, intraoperative semiquantitative Doppler perfusion measurements were conducted during plate osteosynthesis for PHF treatment in our institution between July 2021 and May 2022. The fracture morphology was classified radiologically according to Resch's criteria. Quality of reduction was determined postoperatively to be either anatomical, minor malreduced, or major malreduced according to Peters etal in conventional and computed tomography examinations. Medial hinge integrity and medial metaphyseal extension were assessed radiographically according to Hertel etal. Intraoperatively, after drilling screw holes through the plate, a Doppler probe was inserted through all nine drill holes on the humeral head and at least one on the humeral shaft to successively measure the presence of a pulse to indicate if perfusion is present. A total of ten patients (mean age 59 years, range, 36-83) with a humeral head fracture (2× 2GL, 3× 3G, 2× 4G, 2× 4GL, 1× 5aG according to Resch) were included. Nine of the ten patients showed a pulse signal on the humeral shaft. Overall, pulse-synchronous perfusion was detected using Doppler sonography in at least one hole in the humeral head of all patients. In patients with an intact medial hinge (N=6), pulse-synchronous perfusion could be measured in almost twice as many humeral head holes on average (5.7 vs. 3.0 drill holes) compared to patients with a dislocated medial hinge (N=4). In patients with metaphyseal extension (N=3), pulse-synchronous perfusion was measured in an average of 6.7 humeral head holes compared to 3.7 holes in patients without metaphyseal extension (N=7). Semiquantitative, intraoperative Doppler flowmetry offers a noninvasive and rapid assessment of humeral perfusion which allows an understanding of humeral head perfusion, when used in a standardized fashion to measure flow in different areas of the humeral head.

Chronic hypertension alters the relationship between collateral blood flow cortical cerebral blood flow, and brain tissue oxygenation

This study measured the relationship between pial collateral (leptomeningeal anastomoses, LMA) flow, intraparenchymal cortical cerebral blood flow (cCBF) and brain tissue oxygenation (btO2) during acute ischemic stroke to investigate how pial flow translates to downstream cCBF and btO2 and examined how this relationship is altered in hypertension. Proximal transient middle cerebral artery occlusion (tMCAO) was performed in male Wistar (n = 8/group) and Spontaneously Hypertensive Rats (SHR, n = 8/group). A combination laser Doppler-oxygen probe was placed within the expected cortical peri-infarct in addition to a surface laser doppler probe which measured LMA flow. Phenylephrine (PE) was infused 30 minutes into tMCAO to increase blood pressure (BP) by 30% for 10 minutes and assessed CBF autoregulation. During the initial 30-minute period of tMCAO, btO2 and cCBF were lower in SHR compared to Wistar rats (btO2: 11.5 ± 10.5 vs 17.5 ± 10.8 mmHg and cCBF: −29.7 ± 23.3% vs −17.8 ± 41.9%); however, LMA flow was similar between groups. The relationship between LMA flow, cCBF and btO2 were interdependent in Wistar rats. However, this relationship was disrupted in SHR rats and partially restored by induced hypertension. This study provides evidence that cCBF and btO2 were diminished during tMCAO in chronic hypertension, and that induced hypertension was beneficial regardless of hypertensive status.

Assessment of volume flow rate in arteriovenous fistulas with a novel ultrasound Doppler device (earlybird): Trend analysis, comparison of methods, and inter- and intra-rater reliability.

An accessible tool is required to analyze volume flow trends in arteriovenous fistulas for hemodialysis. Earlybird, an easy-to-place ultrasound Doppler device, has shown comparable accuracy to duplex ultrasound. In this study, we compared volume flow measurements obtained with duplex ultrasound and the dilution technique to an enhanced earlybird device, featuring a dual Doppler probe system, eliminating the requirement for a known insonation angle. Nine patients with a distal radiocephalic arteriovenous fistula were monitored for 12 months with regular volume flow measurements. Correlation and inter- and intra-class reliability analyses were conducted. An overall moderate correlation was observed between earlybird and duplex ultrasound or dilution technique (intraclass correlation coefficient = 0.606 (95% confidence interval 0.064, 0.721) and 0.581 (0.039, 0.739), respectively). Duplex ultrasound compared to dilution measurements, demonstrated an overall moderate correlation (0.725 (0.219, 0.843)). Correlation between earlybird and duplex ultrasound was stronger for the arteriovenous fistula (0.778 (0.016, 0.901)) than the brachial artery (0.381 (-0.062, 0.461)). For earlybird, inter-rater reliability was excellent for the arteriovenous fistula (0.907 (0.423, 0.930)) and poor for the brachial artery (0.430 (0.241, 0.716)). Duplex ultrasound showed a good inter-rater reliability (arteriovenous fistula: 0.843 (0.610, 0.871), brachial artery: 0.819 (0.477, 0.864)). The overall intra-rater reliability was good for duplex ultrasound (rater A: 0.893 (0.727, 0.911); rater B: 0.853 (0.710, 0.891)), while excellent for earlybird (rater A: 0.905 (0.819, 0.928); rater B: 0.921 (0.632, 0.969)). We observed a weaker correlation in the measurements of volume flow rates in arteriovenous fistulas when obtained using earlybird compared to dilution technique, unlike the comparison between duplex ultrasound and the dilution technique. However, inter-rater reliability for the arteriovenous fistula was excellent with earlybird and good with duplex ultrasound, indicating the potential of earlybird as a tool for frequent measurements, enabling trend surveillance and predicting adverse outcomes.

Unraveling a Novel Mechanism of Altered Glomerular Hemodynamics in Pre-diabetic Obesity

Background: In pre-diabetic obesity, disrupted glomerular autoregulation leads to increased glomerular capillary pressure and renal blood flow, causing potential barotrauma-induced glomerular damage. A decrease in Afferent arteriole ( Af-Art) resistance causes higher glomerular capillary pressure but the underlying mechanism behind this, specifically in pre-diabetic obesity, remains unclear. Hyperinsulinemia is common in pre-diabetic obesity, but its role in reducing Af-Art resistance in the kidneys is unknown. Kidney blood flow is auto-regulated by vasoconstriction via tubuloglomerular feedback (TGF) and vasodilation through the Distal convoluted tubule-2/connecting tubule (DCT-2/CNT) mechanism. Our earlier studies indicate increased Af-Art dilation in pre-diabetic obese rats through the DCT-2/CNT mechanism without affecting TGF. This DCT-2/CNT induced Af-Art dilation requires initiation from epithelial sodium channels (ENaC) present at this tubular segment and interestingly insulin is a known ENaC activator. Hypothesis: We hypothesize that in the context of pre-diabetic obesity, hyperinsulinemia contributes to an increase in renal cortical blood flow (CBF) by increasing DCT-2/CNT-induced Af-Art dilation, subsequently leading to glomerular injury. Methods: We assessed the effects of insulin on Af-Art dilation by perfusing juxtaposed DCT-2/CNT segments with insulin in normal rabbits. Contribution of DCT-2/CNT induced Af-Art dilation was measured by co-administration of the ENaC blocker benzamil. To study hyperinsulinemia's role in an in-vivo setting without altering blood glucose levels, we used a hyperinsulinemic-euglycemic (HI-EUG) clamp in obese rats with intravenous (IV) glucose and insulin infusions. Renal CBF and blood pressure were monitored using a laser Doppler probe and femoral artery catheter, respectively, both with and without benzamil administration (400 μg/kg, IV). To evaluate insulin's potential role in causation of renal damage, we infused insulin directly into one kidney of lean rats for 6 weeks via a renal sub-capsular catheter, with the contralateral kidney serving as control. Glomerular basement membrane (GBM) thickness, a marker of renal damage, was measured via electron microscopy. Untargeted lipidomic analysis of the renal cortex was performed to identify potential renal damage pathways in insulin infused kidneys. Results: Insulin perfusion in rabbits' DCT-2/CNT potentiated the dilation of adherent Af-Art compared to control infusions with artificial tubular fluid. ENaC inhibition reversed the insulin-induced Af-Art dilation, confirming that insulin increases Af-Art dilation through the ENaC-initiated DCT-2/CNT mechanism. In obese rats, insulin delivery using a HI-EUG clamp resulted in a significant 20.8±4.9% increase in CBF, which was negated by the administration of the ENaC blocker benzamil, indicating the potential involvement of DCT-2/CNT-mediated vasodilation. Neither the HI-EUG clamp nor benzamil infusion affected blood pressure. Additionally, continuous direct insulin infusion into the kidneys of lean rats led to an increase in glomerular basement membrane (GBM) thickness and ceramide accumulation in the renal cortex, both indicative of renal damage. Conclusion: Our study demonstrates that insulin directly augments DCT-2/CNT-mediated Af-Art dilation and increases renal cortical blood flow in obese rats. Chronic renal insulin infusion led to structural changes and damage markers in the kidney, independent of blood glucose and blood pressure levels. Henry Ford Health System Internal Funding. Pilot and Feasibility grant from southeast center for integrated metabolomics. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

An overview of current assessment techniques for evaluating cutaneous perfusion in reconstructive surgery.

This article provides a comprehensive analysis of modern techniques used in the assessment of cutaneous flaps in reconstructive surgery. It emphasizes the importance of preoperative planning and intra- and perioperative assessment of flap perfusion to ensure successful outcomes. Despite technological advancements, direct clinical assessment remains the gold standard. We categorized assessment techniques into non-invasive and invasive modalities, discussing their strengths and weaknesses. Non-invasive methods, such as acoustic Doppler sonography, near-infrared spectroscopy, hyperspectral imaging thermal imaging, and remote-photoplethysmography, offer accessibility and safety but may sacrifice specificity. Invasive techniques, including contrast-enhanced ultrasound, computed tomography angiography, near-infrared fluorescence angiography with indocyanine green, and implantable Doppler probe, provide high accuracy but introduce additional risks. We emphasize the need for a tailored decision-making process based on specific clinical scenarios, patient characteristics, procedural requirements, and surgeon expertise. It also discusses potential future advancements in flap assessment, including the integration of artificial intelligence and emerging technologies.

Transanal Hemorrhoidal Dearterialization (THD): A Single Center Experience on 100 Consecutive Cases

Introduction. Surgeons, using all available means for the treatment of the hemorrhoidal disease, must make compromises between the radicality of the potential surgical treatment (to prevent recurrence) and the maintenance of the postoperative functionality of the anorectum (avoiding stricture, anal fissures, incontinence, reduction of postoperative pain etc.). Materials and methods. All patients treated with the THD method using a system manufactured by THD S.p.A., Correggio, Italy, consisting of a proctoscope equipped with a Doppler probe and a light source was used to perform the operation. Results. Out of 100 operated patients, 64 (64%) were men and 36 (36%) were women. 54 patients had third degree hemorrhoidal disease, 32 had fourth degree, 7 patients had fourth degree hemorrhoidal disease with active bleeding and 7 patients had second degree hemorrhoidal disease with active bleeding. In the follow-up period, anal fissure formation in two patients and prolapse of a hemorrhoidal node in a treated patient with fourth-degree hemorrhoidal disease were noted. Discussion. It is estimated that more than 50% of the general population will experience at least one episode of symptomatic hemorrhoids during their lifetime. Morphological and hemodynamic changes that occur in patients with hemorrhoidal disease is the finding of an increased diameter of the terminal branches of the superior rectal artery that supplies the hemorrhoidal nodes. These branches are 10–11 in number, of which ligation of up to six is allowed for effective treatment with the THD method. Conclusion. If the THD technique is used according to the established standards, postoperative complications in patients in the form of fecal incontinence and chronic pain have not been described, which is also confirmed in our series. The absence of serious complications while addressing a hemorrhoidal disease at the level of the cause of its occurrence, makes the THD+mucopexy technique applicable in most cases. Correct manipulation of the instruments, precision in dearterization, mucopexy of the rectal mucosa and submucosa are imperative for achieving excellent results.

Experimental and numerical investigation of flow dynamics in an upward bubbly flow in a tube undergoing oscillating rolling motion

Offshore nuclear power plants are characterized by a potential oscillatory motion depending on ocean waves. Investigating the local flow behavior in a system undergoing oscillating motion is necessary. In particular, because the local void fraction near the heating element surface significantly affects the nucleating boiling heat transfer and critical heat flux, understanding the dynamic behavior of the local void fraction is very important. Therefore, in this study, as an essential first step in predicting boiling heat transfer and departure from nucleate boiling in offshore nuclear reactors, the dynamic behavior of air–water bubbly flows has been experimentally and numerically investigated in a tube under oscillatory rolling conditions. An optical fiber Doppler probe was used to measure the local bubble parameters. The effects of the rolling period on the void fraction distributions, bubble sizes, and bubble velocities were insignificant. However, the rolling amplitude effect was significant. The void fraction was the highest at the downward-facing wall when the tube was at its maximum tilt. Moreover, the local water velocity became the highest when the tube returned to near vertical because of the combined effect of gravity and Euler force. These findings provide insights into understanding the characteristics of bubbly flow in a rolling tube.

Body Mass Index Is Associated With Myocutaneous Free Flap Reliability: Overcoming the Obesity Obstacle With a Proposed Clinical Algorithm to Identify and Manage High-Risk Patients Undergoing Gracilis Free Flap With Skin Paddle Harvest.

The purpose of this study was to evaluate the role of body mass index (BMI) in predicting postoperative complications following myocutaneous free flap transfer. In addition, we sought to identify certain body composition variables that may be used to stratify patients into low- versus high-risk for gracilis myocutaneous free flap with skin paddle failure. Using the National Surgical Quality Improvement Program database, we collected data for all patients who underwent myocutaneous free flap transfer from 2015 to 2021. Demographic data, medical history, surgical characteristics, and postoperative outcomes, including complications, reoperations, and readmissions, were collected. Body mass index was correlated with outcome measures to determine its role in predicting myocutaneous free flap reliability. Subsequently, we retrospectively obtained measurements of perigracilis anatomy in patients who underwent computed tomography angiography bilateral lower extremity scans with intravenous contrast at our institution. We compared body composition data with mathematical equations calculating the potential area along the skin of the thigh within which the gracilis perforator may be found. Across the United States, 1549 patients underwent myocutaneous free flap transfer over the 7-year study period. Being in obesity class III (BMI ≥40 kg/m2) was associated with a 4-times greater risk of flap complications necessitating a return to the operating room compared with being within the normal BMI range. In our computed tomography angiography analysis, average perigracilis adipose thickness was 18.3 ± 8.0 mm. Adipose thickness had a strong, positive exponential relationship with the area of skin within which the perforator may be found. In our study, higher BMI was associated with decreased myocutaneous free flap reliability. Specifically, inner thigh adipose thickness can be used to estimate the area along the skin within which the gracilis perforator may be found. This variable, along with BMI, can be used to identify patients who are considered high-risk for flap failure and who may benefit from additional postoperative monitoring, such as the use of a color flow Doppler probe and more frequent and prolonged skin paddle monitoring.

Variability of anterolateral thigh flap perforator locations - clinical implications.

<b><br>Introduction:</b> The anterolateral thigh flap is an example of a free flap widely applied for reconstruction of tissues within various areas of the body.</br> <b><br>Aim:</b> The aim of the study was to determine the most common locations of the ALT flap perforators in men and women as well as to clarify any potential differences in the location of the vessel in male vs. female subjects.</br> <b><br>Material and method:</b> In years 2021-2022, a study was conducted at the Plastic, Reconstructive, and Aesthetic Surgery Clinic in a group of 90 volunteers (45 women and 45 men, a total of 180 lower extremities) to determine the location of the anterolateral thigh flap perforator against the flap surface using a portable Doppler probe.</br> <b><br>Results:</b> Variable locations were revealed for the anterolateral thigh flap perforator within the study. In women, the perforator is located more distally from the anterior superior iliac spine, most frequently within the inferolateral quadrant, while being located closer to the anterior superior iliac spine, and most frequently within the superolateral quadrant, in men. No perforator was found in 3.3% of the examined limbs. No statistically significant differences were observed between the course of the perforators within the left and right lower limbs in individual patients.</br> <b><br>Conclusions:</b> The location of the ALT flap perforator is subject to sexual dimorphism, which facilitates the investigation area being narrowed down to the well-defined locations of its most frequent occurrence when planning anterolateral thigh flap reconstructive procedures.</br&gt.

Supercharging DIEP Flaps Using Contralateral Superficial Inferior Epigastric Vein Grafts

Introduction: Venous congestion, even with a patent deep venous anastomosis, can afflict some DIEP (Deep Inferior Epigastric Perforator) flaps and various techniques of superficial venous supercharging have been described, although the indications for its use are not consensual. The main goal of this study is to confirm that superficial venous supercharge of DIEP flaps, utilizing the contralateral Superficial Inferior Epigastric Vein (SIEV) as an interposition vein graft, is feasible and functional. Materials and Methods: We retrospectively reviewed all DIEP flap breast reconstruction patients treated at our institution between June 2016 and December 2017 and that met all the inclusion criteria: Unilateral breast reconstruction with a DIEP flap; flap weighing more than 750 gm; supercharging of the ipsilateral superficial venous system; contralateral SIEV interposition graft; implantable doppler probe in the superficial system for at least 5 days. In the technique described here, the contralateral SIEV graft was harvested and anastomosed to the ipsilateral SIEV, obtaining this way a long vein that easily reaches the recipient vein (distal end of the Internal Mammary Vein - IMV). A Doppler probe was implanted in the superficial system, for at least 5 postoperative days, to monitor the function of this supercharging. We also analyzed the patient’s history, flaps weight, number and perforator rows, recipient vessels, SIEV graft length and diameter and all perioperative complications. Results: Ten patients met all inclusion criteria. They were treated using this technique and analyzed. Two patients had some type of alteration of the Doppler signal and clinical signs of venous congestion. They were surgically revised with success and were analyzed in detail. No total or partial flap failures were found. Clinical fat necrosis was also absent. Conclusion: This technique seems to be feasible, functional and adds an extra length to ipsilateral SIEV to reach a recipient vein. This way, the flap inset is not compromised by a short SIEV. No further significant morbidity is added for SIEV harvest that is in the same operative field, unlike the saphenous or cephalic veins. In selected patients, it could be an alternative supercharging technique.

Can the change of vasomotor activity in irritable bowel syndrome patients be detected via color Doppler ultrasound?

Irritable bowel syndrome (IBS) is one of the most frequently referred conditions to the gastrointestinal outpatient clinic. The pathophysiology of IBS has not been determined with certainty. Visceral hypersensitivity is indicated as one of the pathophysiologies. The sympathetic nervous system is primarily in charge of controlling the arteries, and its effect is vasospasm in the medium and large arteries, resulting in decreased blood flow. To demonstrate, using Doppler evaluation of the brachial artery, that sympathetic activity impairs vasomotor performance due to autonomic neuropathy, which we believe is associated with IBS. There were 58 participants in the study. The control group consisted of 29 healthy patients, while the remaining 29 patients had been diagnosed with IBS. Patients who met the Rome IV criteria and had IBS were included in the study. People with known polyneuropathy or non-IBS chronic conditions that can progress were excluded from the trial, as were those with essential hypertension, diabetes mellitus, cardiovascular disease, or peripheral arterial disease, and patients diagnosed with anxiety or depression. Those with moderate to severe carpal tunnel syndrome or a median nerve lesion due to trauma were also excluded from the trial. A Doppler probe was used to measure the baseline diameter and flow rates of the brachial artery from 2 cm superior to the antecubital fossa. The Doppler probe remained stationary throughout the experiment, allowing for continuous measurements. Then, to activate the sympathetic fibers, an electrical stimulus for 5 s with an intensity of 10 mA and a frequency of 1 Hz was applied to the median nerve at the wrist level via the bipolar stimulus electrode. The artery diameter and flow rates were measured again immediately following the fifth stimulus. In healthy persons with no history of chronic illness, there was a statistically significant decrease in flow rate after stimulation (P < 0.001). In addition, stimulation resulted in a statistically significant reduction in the diameter of the brachial artery (P < 0.001). Patients diagnosed with IBS had statistically significant vasodilation and an increase in flow rate. Sympathetic stimulation causes a reduction in vascular diameter and blood flow, whereas it has the reverse effect on IBS patients. In investigating the involvement of autonomic neuropathy in the development of IBS, significant changes in brachial artery Doppler parameters were observed before and after stimulation of the median nerve with low-current sensory stimulation. This method is thought to be more user-friendly and comfortable than other methods described in the literature.

Negative Pressure Wound Therapy in Free Muscle Flaps-Risk or Benefit?

Application of negative pressure wound therapy (NPWT) on free flaps not only reduces edema but also increases the pressure from outside. The impact of these opposite effects on flap perfusion remains elusive. This study evaluates the NPWT system's influence on macro- and microcirculation of free flaps and edema reduction to better assess the clinical value of this therapy in microsurgical reconstructions. In this open-label, prospective cohort study, a total of 26 patients with free gracilis muscle flaps for distal lower extremity reconstruction were included. Flaps were covered with an NPWT (13 patients) or a conventional, fatty gauze dressing (13 patients) for 5 postoperative days (PODs). Changes in flap perfusion were analyzed by laser Doppler flowmetry, remission spectroscopy, and an implanted Doppler probe. Flap volume as a surrogate parameter for flap edema was evaluated by three-dimensional (3D) scans. No flap showed clinical evidence of circulatory disturbances. The groups showed significant differences in the dynamic of macrocirculatory blood flow velocity with an increase in the NPWT group and a decelerated flow in the control group from PODs 0 to 3 and PODs 3 to 5. No significant differences in microcirculation parameters were observed. 3D scans for estimation of edema development demonstrated significant differences in volume dynamics between the groups. Flap volume of the controls increased, while the volume in the NPWT group decreased during the first 5 PODs. The volume of NPWT-treated flaps decreased even further after NPWT removal from PODs 5 to 14 and significantly more than the flap volume in the control group. NPWT is a safe form of dressing for free muscle flaps that enhances blood flow and results in a sustainable edema reduction. The use of NPWT dressings for free flaps should therefore be considered not only as a pure wound covering but also as a supportive therapy for free tissue transfer.

Placement of Extracranial Stimulating Electrodes and Measurement of Cerebral Blood Flow and Intracranial Electrical Fields in Anesthetized Mice.

The detection of cerebral blood flow (CBF) responses to various forms of neuronal activation is critical for understanding dynamic brain function and variations in the substrate supply to the brain. This paper describes a protocol for measuring CBF responses to transcranial alternating current stimulation (tACS). Dose-response curves are estimated both from the CBF change occurring with tACS (mA) and from the intracranial electric field (mV/mm). We estimate the intracranial electrical field based on the different amplitudes measured by glass microelectrodes within each side of the brain. In this paper, we describe the experimental setup, which involves using either bilateral laser Doppler (LD) probes or laser speckle imaging (LSI) to measure the CBF; as a result, this setup requires anesthesia for the electrode placement and stability. We present a correlation between the CBF response and the current as a function of age, showing a significantly larger response at higher currents (1.5 mA and 2.0 mA) in young control animals (12-14 weeks) compared to older animals (28-32 weeks) (p < 0.005 difference). We also demonstrate a significant CBF response at electrical field strengths <5 mV/mm, which is an important consideration for eventual human studies. These CBF responses are also strongly influenced by the use of anesthesia compared to awake animals, the respiration control (i.e., intubated vs. spontaneous breathing), systemic factors (i.e., CO2), and local conduction within the blood vessels, which is mediated by pericytes and endothelial cells. Likewise, more detailed imaging/recording techniques may limit the field size from the entire brain to only a small region. We describe the use of extracranial electrodes for applying tACS stimulation, including both homemade and commercial electrode designs for rodents, the concurrent measurement of the CBF and intracranial electrical field using bilateral glass DC recording electrodes, and the imaging approaches. We are currently applying these techniques to implement a closed-loop format for augmenting the CBF in animal models of Alzheimer's disease and stroke.

1D profile measurement of ion velocity distribution with glass-tube-pair type Doppler probe array

We developed a glass-tube-pair type Doppler probe array for ion velocity distribution function measurement with high spatial and time resolution. By four mirrors and four optical fibers fixed in two parallel glass tubes, the light from ions in each measurement area (3.2 × 2.5 × 1.0 cm3) between tubes is collected in three different directions, and the fibers are led to a Czerny–Turner spectrometer and finally to an ICCD camera (the exposure time of 2 μs) for Doppler spectra measurements with high time resolution. Since the Doppler spectrum profile in each viewing line represents the distribution of the ion velocity component in the line, we can reconstruct 2D velocity distribution by the measured spectra in three viewing lines with tomography techniques. We tested the accuracy of some reconstruction methods from spectra to velocity distribution in numerical simulation and chose the iterative method as the best one. By use of this new diagnostic, we successfully measured the radial profile of ion velocity distribution during magnetic reconnection of merging spherical tokamak plasmas and revealed that their ions have anisotropic velocity distributions.

CORRELATION OF LIPOPROTEIN(a) AND CORONARY ARTERY DISEASES

&lt;div&gt;&lt;p&gt;&lt;strong&gt;INTRODUCTION:&lt;/strong&gt; Cardiovascular diseases (CVD) continue to be one of the leading causes of mortality worldwide. While factors such as diabetes, sedentariness, psychostress, genetic predisposition, hypertension, smoking, and hyperlipidemia are well-known in the etiology of atherosclerosis (Ath) of coronary arteries. Recent studies have also identified high concentrations of lipoproteins (a) [Lp(a)] as a risk factor. In fact, high concentrations of Lp(a) above 30mg/dl (reference value-30mg/dl) have been found to be a risk factor for Ath, leading experts to develop medications aimed at reducing Lp(a) concentrations and preventing atherosclerotic manifestations. &lt;a href="https://eas-society.org/"&gt;&lt;em&gt;The European Atherosclerosis Society&lt;/em&gt;&lt;/a&gt; has also released clinical guidelines for testing and treating high concentrations of Lp(a) as part of the global assessment of cardiovascular risk.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;THE GOAL OF THE STUDY:&lt;/strong&gt; The goal of this study is to investigate the concentration of Lp(a) in patients with coronary disease and its connection to the presentation of atherosclerosis of the coronary arteries in patients with CVD compared to a control group of healthy individuals. Through this study, we hope to gain a better understanding of the role of Lp(a) in CVD and its potential as a target for prevention and treatment. By identifying and addressing risk factors like high Lp(a) concentrations, we can work towards reducing the global burden of CVD and improving health outcomes for individuals around the world.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;THE AIM OF THE STUDY:&lt;/strong&gt; The aim of this study is to determine the concentration of lipoprotein(a) in patients with coronary disease, its connectivity and role in the presentation of atherosclerosis of the coronary arteries in patients with CVD compared to the control group of healthy individuals.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;MATERIAL AND METHODS:&lt;/strong&gt; As working material, the blood taken from the vein of patients with coronary disease was used - N0=80, (with an identical average age of 55.70±6.00 years old, of which 35 were female while 45 were male. In the study, there was also a control group: N0=80 healthy volunteers (45 were male and 35 female) with the same age as the patients. Blood for analysis was taken at 8 o'clock in the morning, at room temperature of 19-24°C, every three months in a period of 12 months.&lt;/p&gt;&lt;p&gt;Echocardiography and EKG were also performed on all the patients with Toshiba SSH-140A machine, color Doppler probe 3.7Hz, sectorial type, taking into account as key parameters the thickness of the back wall of the left ventricle and the thickness of-Left ventricular internal diameter end diastole (LVPVd) and interventricular septal end diastole (IVSd&amp;gt;12 mm). Together with the examination of Lp(a) concentrations, the lipid profile was also analyzed. The analyzes were done at the Clinical Laboratory Institute at the University Clinical Center of the Faculty of Medicine – Skopje, North Macedonia.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;STATISTICAL PROCESSING OF THE MATERIAL:&lt;/strong&gt; From the statistical methods, arithmetic mean value, standard deviation X±SD were used. The comparative statistics of the lipid parameters between the analyzed groups were analyzed with students ‘t’ dependent and independent samples according to the Mann-Whitney U-test and Wilcoxon - test. The results of the lipid fractions will be shown tabularly (see table 3) with the statistical program SPSS V26.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;RESULTS:&lt;/strong&gt; The obtained values of lipids (Col.Total, TG, HDL-ch, LDL-ch) and lipoprotein (a) in both groups are presented with mean values and standard deviation X-SD. Due to the fact that in the obtained results of Lp(a) in both sexes, in patients with coronary disease, we did not notice any significant difference, we will present them as common for both groups, with CVD with maximum values of 78.00-16,00 mg/dl while in the control group =15.20-4.30 mg/dl, with a statistically significant difference with p&amp;lt;0.000. The same difference was found from the obtained results of lipid concentrations between the two groups with p &amp;lt;0.0001 (as presented in the tables below).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;CONCLUSION:&lt;/strong&gt; The results obtained in the paper proved that high concentrations of Lp(a) &amp;gt; 30 mg/dl are risk factors for the occurrence of Ath of the coronary arteries and that these patients are at a 5-8 times higher risk for the development of Ath of coronary arteries, compared to individuals with normal Lp(a) values, therefore the treatment of high concentrations of Lp(a) should be started at the beginning of their appearance. In conclusion, we can suggest that the adequate treatment of high Lp(a) concentrations and the balancing of the lipid profile can apparently affect the prevention of atherosclerotic processes of the coronary arteries, therefore we prefer that in individuals with a history of CAD and those with coronary disease, the examination of Lp(a) and lipid profile should be one of the initial examinations during the management of patients with CAD.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;Lipoprotein (a), atherosclerosis, Cardiovascular Arterial Diseases (CAD), lipid profile.&lt;/p&gt;&lt;/div&gt;