Laser Doppler Flowmetry (laser + doppler_flowmetry)

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Laser Doppler Flowmetry

  • scanning laser doppler flowmetry


  • Selected Abstracts


    Association between optic nerve head blood flow as assessed with Laser Doppler Flowmetry and mean arterial blood pressure in glaucoma, ocular hypertension and healthy control subjects

    ACTA OPHTHALMOLOGICA, Issue 2009
    D SCHMIDL
    Purpose It has been implicated that vascular dysregulation plays a role in the pathogenesis of primary open angle glaucoma (POAG). In the present study the association between optic nerve head blood flow as measured with laser Doppler flowmetry and ocular perfusion pressure in patients with treated and untreated POAG, patients with ocular hypertension and healthy control subjects was compared. Methods 136 patients with treated POAG, 116 patients with untreated POAG, 138 patients with ocular hypertension and 160 control subjects were included in the study. Optic nerve head blood flow was assessed using laser Doppler flowmetry. Ocular perfusion pressure was calculated based on measurement of IOP and systemic hemodynamics. Results Optic nerve head blood flow was significantly reduced in patients with glaucoma compared to patients with ocular hypertension and healthy subjects (p<0.01). However, no difference in optic nerve head blood flow between treated and untreated glaucoma patients was detected. The highest association between ocular perfusion pressure and optic nerve head blood flow was found in untreated glaucoma patients followed by ocular hypertensives and treated glaucoma patients. Conclusion The present study confirms evidence that optic nerve head blood flow is reduced in patients with POAG and patients with ocular hypertension. Correlation coefficients in the glaucoma groups and in the ocular hypertensives indicate a vascular dysregulation in these patients compared to healthy control subjects. [source]


    Laser Doppler flowmetry in endodontics: a review

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2009
    H. Jafarzadeh
    Abstract Vascular supply is the most accurate marker of pulp vitality. Tests for assessing vascular supply that rely on the passage of light through a tooth have been considered as possible methods for detecting pulp vitality. Laser Doppler flowmetry (LDF), which is a noninvasive, objective, painless, semi-quantitative method, has been shown to be reliable for measuring pulpal blood flow. The relevant literature on LDF in the context of endodontics up to March 2008 was reviewed using PubMed and MEDLINE database searches. This search identified papers published between June 1983 and March 2008. Laser light is transmitted to the pulp by means of a fibre optic probe. Scattered light from moving red blood cells will be frequency-shifted whilst that from the static tissue remains unshifted. The reflected light, composed of Doppler-shifted and unshifted light, is returned by afferent fibres and a signal is produced. This technique has been successfully employed for estimating pulpal vitality in adults and children, differential diagnosis of apical radiolucencies (on the basis of pulp vitality), examining the reactions to pharmacological agents or electrical and thermal stimulation, and monitoring of pulpal responses to orthodontic procedures and traumatic injuries. Assessments may be highly susceptible to environmental and technique-related factors. Nonpulpal signals, principally from periodontal blood flow, may contaminate the signal. Because this test produces no noxious stimuli, apprehensive or distressed patients accept it more readily than current methods of pulp vitality assessment. A review of the literature and a discussion of the application of this system in endodontics are presented. [source]


    The acute effects of smokeless tobacco (snuff) on gingival blood flow in man

    JOURNAL OF PERIODONTAL RESEARCH, Issue 4 2001
    Antonios Mavropoulos
    Snuff-induced blood flow responses in the gingiva were evaluated in 22 healthy casual consumers of tobacco. Laser Doppler flowmetry (LDF) was used to measure blood flow simultaneously and continuously on two gingival sites (buccal aspect of the papillae between the upper lateral incisors and canines). In addition, measurements of skin blood flow in the forehead and palmar side of the left thumb were performed. Arterial blood pressure (BP) and heart rate (HR) were also recorded. Unilateral application of commercial snuff (500 mg, 1%) caused a marked and rapid increase in gingival blood flow (GBF) on the exposed side (p<0.001). Blood flow increased also in the contralateral gingiva and forehead skin (p<0.05). Skin blood flow in the thumb showed an insignificant decrease. BP and HR increased. Vascular conductance increased significantly in the snuff-exposed gingiva but not in the contralateral gingiva or the forehead. Vascular conductance was largely unaffected in the thumb. It is concluded that acute application of snuff, besides giving rise to typical changes in BP and HR, increases GBF in and around the exposed area, probably through activation of sensory nerves and the subsequent release of vasodilatory peptides from their peripheral endings. Blood flow in unexposed gingival and forehead skin may increase probably due to humoral or nervously mediated mechanisms. However, a passive pressure-induced hyperaemia in the unexposed gingiva and forehead skin can not be excluded. [source]


    Microcirculatory Responses To Electrical Spinal Cord Stimulation In Painful Diabetic Neuropathy And Other Painful Conditions

    JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000
    Nd Harris
    Electrical spinal cord stimulation (ESCS) has been used to provide pain relief in a number of conditions, including painful diabetic neuropathy (PDN). ESCS has also been shown to increase microvascular blood flow in peripheral vascular disease. If nerve hypoxia contributes to pain in PDN, ESCS may relieve this by increasing nerve blood flow. We have therefore investigated skin and sural nerve microvascular responses to ESCS. We studied subjects implanted with ESCS for pain relief, 4 had PDN and 7 were controls with other painful conditions. Blood flow, before and during stimulation, was assessed using Laser Doppler flowmetry. Only one (PDN) subject showed a statistically significant increase in skin blood flow during stimulation. The three remaining PDN subjects showed significant reductions in skin blood flow, as did 3/7 of controls. Sural nerve blood flow was measured on a separate occasion. During stimulation nerve blood flow increased in 1 (control) subject, decreased in 1 (PDN) subject and did not change in the other 5 tested (3 PDN and 2 control). In summary, ESCS did not produce any consistent increase in skin or nerve microvascular blood flow. ESCS reduces pain in a variety of different conditions, however this does not appear to be mediated by changes in blood flow. Until a thorough understanding of the pathogenic mechanisms causing PDN is achieved, therapy will be limited to providing symptomatic relief. [source]


    Age-related macular degeneration: hemodynamic changes

    ACTA OPHTHALMOLOGICA, Issue 2009
    CJ POURNARAS
    Purpose Metabolic changes of the RPE associated to the dysfunction of choriocapillaries(CC)/RPE complex may induces the AMD-related changes. Additional vascular changes in the choroid potentially have deleterious effects on the RPE. Methods Quantification of CC number and lumen diameters in cross sections and alkaline phosphatase (APase) flat-embedding technique, expressing high constitutive APase activity in choriocapillaris and choroidal veins on human RPE/Bruch's Membrane/CC complex, significantly contributed to the analysis of the choroidal vasculature. Laser Doppler flowmetry (LDF) data provided additional information on the assessment of hemodynamic changes in AMD. Results Choroidal vascular density reduction and significant vasoconstriction of the choriocapillaries, occurs during the evolution of AMD. In eyes with geographic atrophy, the RPE degenerates first while CC loss is secondary to RPE degeneration. In eyes with exudative AMD, degeneration of the CC layer occurs while RPE is still functional. LDF data indicated choroidal blood flow decrease according to age and the degree of severity of AMD; the decrease in flow preceding the formation of choroidal CNV, strongly suggest that these changes may have a role in the development of CNV. As a result of vascular dysfunction, the choroidal blood flow is dysregulated in patients with neovascular AMD. The choroidal watershed zone (WZ) courses through the fovea more often in patients suffering from AMD than in age-matched controls, particularly in the presence of CNV. Choroidal neovascularisation usually arises within these WZ. Conclusion The role of choroidal ischemia in the pathophysiology of AMD is supported by the observed choroidal microcirculation anatomical and fucntional abnormalities. [source]


    Effect of glaucoma and glaucoma risk factors on choroidal hemodynamics

    ACTA OPHTHALMOLOGICA, Issue 2009
    W ABOU SAMRA
    Purpose a) to determine subfoveal choroidal hemodynamics in patients with primary open angle glaucoma (POAG) and patients with ocular hypertension (OH); b) to assess the effects of diabetes (DM), systemic hypertension (SHT) and myopia on subfoveal choroidal hemodynamics Methods Laser Doppler flowmetry (LDF) was used to determine the subfoveal choroidal blood velocity (ChBVel), volume (ChBVol), and flow (ChBF) in 1) patients with POAG (n=85) and patients with OHT (n=25); 2) patients with glaucoma risk factors which were further subdivided into three subgroups; DM (n=93), SHT (n=57) and myopia (n=29) respectively. Subjects with each risk factor were further subdivided into two subgroups (without and with POAG), 3) age matched healthy controls (n=100). Results All LDF parameters were significantly reduced in all groups of patients compared with age matched controls. No statistically significant differences in the LDF parameters among HTG, NTG and OHT subgroups were detected. No significant difference in the LDF parameters between the two subgroup of each risk factor (without and with POAG) was noted. The LDF data of glaucomatous patients with risk factors demonstrated a significant reduction of ChBF and an increase in resistance in comparison to glaucomatous patients without risk factors Conclusion Subfoveal choroidal LDF parameters are reduced in subjects with POAG, OHT and patients with glaucoma risk factors, such as DM, SHT (under antihypertensive therapy) and myopia when compared with age matched healthy controls. However, the role of these choroidal circulatory alterations in the development or progression of the glaucomatous optic neuropathy remains to be clarified. [source]


    Evaluation of sympathetic vasoconstrictor response following nociceptive stimulation of latent myofascial trigger points in humans

    ACTA PHYSIOLOGICA, Issue 4 2009
    Y. Kimura
    Abstract Aim:, Myofascial trigger points (MTrPs) are a major cause of musculoskeletal pain. It has been reported that stimulation of a latent MTrP increases motor activity and facilitates muscle pain via activation of the sympathetic nervous system. However, the magnitude of the sympathetic vasoconstrictor response following stimulation of MTrP has not been studied in healthy volunteers. The aims of this study were to (1) evaluate the magnitude of the vasoconstrictor response following a nociceptive stimulation (intramuscular glutamate) of MTrPs and a breath-hold manoeuvre (activation of sympathetic outflow) and (2) assess whether the vasoconstrictor response can be further modulated by combining a nociceptive stimulation of MTrPs and breath-hold. Methods:, Fourteen healthy subjects were recruited in this study. This study consisted of four sessions (normal breath group as control, breath-hold group, glutamate MTrP injection group and glutamate MTrP injection + breath-hold group). Skin blood flow and skin temperature in both forearms were measured with laser Doppler flowmetry and infrared thermography, respectively, in each session (before the treatment, during the treatment and after the treatment). Results:, Glutamate injection into MTrPs decreased skin temperature and blood flow in the peripheral area. The magnitudes of the reduction were comparable to those induced by the breath-hold manoeuvre, which has been used to induce sympathetic vasoconstrictor response. Conclusion:, The combination of glutamate injection into latent MTrPs together with the breath-hold manoeuvre did not result in further decrease in skin temperature and blood flow, indicating that sympathetic vasoconstrictor activity is fully activated by nociceptive stimulation of MTrPs. [source]


    Pulp revascularization of replanted immature dog teeth after treatment with minocycline and doxycycline assessed by laser Doppler flowmetry, radiography, and histology

    DENTAL TRAUMATOLOGY, Issue 2 2004
    Alessandra Luisa de Souza Ritter
    Abstract,,, This study investigated the effect of topical antibiotic treatment on pulp revascularization in replanted teeth. Thirty-four immature teeth were selected from three young dogs. Baseline radiographs and laser Doppler flowmetry (LDF) readings were obtained. Specimens were randomly divided into four groups: Thirty-eight teeth were extracted, kept dry for 5 min, and either (Group 1) covered with minocycline mixture (G1, n = 11), (Group 2) soaked in doxycycline (G2, n = 11), or (Group 3) soaked in saline (G3-negative control, n = 6), and replanted. Teeth in Group 4 were not extracted (positive control, n = 6). Postoperative radiographs and LDF readings were obtained for 2 months after replantation. After sacrifice, the jaws were collected and processed for light microscopy. Pre- and postreplantation LDF readings and radiographs, and histologic findings were analyzed to assess revascularization. Pulp revascularization occurred in 91% (G1), 73% (G2), and 33% (G3) of the specimens. In conclusion, minocycline facilitates pulp revascularization in replanted immature teeth after replantation. [source]


    Efficacy of laser Doppler flowmetry for the diagnosis of revascularization of reimplanted immature dog teeth

    DENTAL TRAUMATOLOGY, Issue 2 2001
    Kallaya Yanpiset
    Abstract , This study was performed to assess if laser Doppler flowmetry (LDF) is an improved method for the detection of revascularization of replanted teeth. Teeth were extracted and reimplanted under different experimental conditions. LDF readings were taken before extraction and weekly for 3 months. In control teeth, LDF baseline readings were taken and then repeated after the apical blood vessels were cut surgically. At the end of 3 months it was determined radiographically and histologically whether revascularization had occurred, i.e. vitality had returned. Results: LDF readings correctly predicted the pulp status (vital vs. non-vital) in 83.7% of the readings. 73.9% (17 of 23) were correct for the vital teeth and 95% (19 of 20) were correct for the non-vital teeth. Fisher's exact test (2-tail) indicated that there was no significant association between the efficacy of LDF and tooth type (P=0.166), although P2 was the least accurate tooth tested. Wilcoxon's matched-pair signed rank test demonstrated that in the revascularized (vital) teeth, the flux value between the baseline and week 2 dropped significantly (P=0.0001), increased significantly from week 2 to week 4 (P=0.0001) and then decreased steadily until week 12. However, at week 12 the flux was still significantly higher than at week 2 (P=0.010). In the teeth that failed to revascularize, the flux value dropped significantly by weeks 1 and 2 (P=0.004 and P=0.0001, respectively). Flux values did not increase from week 2. A Fast Fourier Transform (FFT) analysis confirmed a pulse of dominant frequency of 2 Hz in the teeth that returned to vitality and the lack thereof in those that stayed non-vital. One tooth in which the flux value evaluation indicated a non-vital tooth but the radiographic/histologic findings showed vital (false negative) possessed a pulse of dominant frequency and proved by this method to have successfully revascularized. [source]


    Technical equipment for assessment of dental pulp status

    ENDODONTIC TOPICS, Issue 1 2004
    Thomas R. Pitt Ford
    Assessment of dental pulp status is normally undertaken using thermal or electrical tests that indicate the functioning of A, nerve fibers. The tests are quick and usually reliable, although nothing is absolute. Newer tests have involved assessment of blood flow, and of these laser Doppler flowmetry has been the most widely used and beneficial to patients particularly after traumatic injury. The high cost of flowmeters and the time-consuming procedure have limited uptake. [source]


    Epilepsy Patients Treated with Antiepileptic Drug Therapy Exhibit Compromised Ocular Perfusion Characteristics

    EPILEPSIA, Issue 11 2002
    Emma J. Roff Hilton
    Summary: ,Purpose: Reduced cerebral blood flow and decreased cerebral glucose metabolism have been identified in patients with epilepsy treated with antiepileptic drug (AED) therapy. The purpose of this study was to determine whether ocular haemodynamics are similarly reduced in patients with epilepsy treated with AEDs. Methods: Scanning laser Doppler flowmetry was used to measure retinal capillary microvascular flow, volume, and velocity in the temporal neuroretinal rim of 14 patients diagnosed with epilepsy (mean age, 42.0 ± 0.9 years). These values were compared with those of an age- and gender-matched normal subject group (n = 14; mean age, 41.7 ± 0.3 years). Student's unpaired two-tailed t tests were used to compare ocular blood-flow parameters between the epilepsy and normal subject groups (p < 0.05; Bonferroni corrected). Results: A significant reduction in retinal blood volume (p = 0.001), flow (p = 0.003), and velocity (p = 0.001) was observed in the epilepsy group (13.52 ± 3.75 AU, 219.14 ± 76.61 AU, and 0.77 ± 0.269 AU, respectively) compared with the normal subject group (19.02 ± 5.11 AU, 344.03 ± 93.03 AU, and 1.17 ± 0.301 AU, respectively). Overall, the percentage mean difference between the epilepsy and normal groups was 36.31% for flow, 28.92% for volume, and 34.19% for velocity. Conclusions: Patients with epilepsy exhibit reduced neuroretinal capillary blood flow, volume, and velocity compared with normal subjects. A reduction in ocular perfusion may have implications for visual function in people with epilepsy. [source]


    Free fatty acids exert a greater effect on ocular and skin blood flow than triglycerides in healthy subjects

    EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 8 2004
    M. Bayerle-Eder
    Abstract Background, Free fatty acids (FFAs) and triglycerides (TGs) can cause vascular dysfunction and arteriosclerosis. Acute elevation of plasma FFA and TG concentration strongly increase ocular and skin blood flow. This study was designed to discriminate whether FFA or TG independently induce hyperperfusion by measuring regional and systemic haemodynamics. Methods, In a balanced, randomized, placebo-controlled, double-blind, three-way, crossover study nine healthy subjects received either Intralipid® (Pharmacia and Upjohn, Vienna, Austria) with heparin, Intralipid® alone or placebo control. Pulsatile choroidal blood flow was measured with laser interferometry, retinal blood flow and retinal red blood cell velocity with laser Doppler velocimetry, and skin blood flow with laser Doppler flowmetry during an euglycaemic insulin clamp. Results, A sevenfold increase of FFA during Intralipid®/heparin infusion was paralleled by enhanced choriodal, retinal, and skin blood flow by 17 ± 4%, 26 ± 5% (P < 0·001), and 47 ± 19% (P = 0·03) from baseline, respectively. In contrast, a mere threefold increase of FFA by infusion of Intralipid® alone did not affect outcome parameters, despite the presence of plasma TG levels of 250,700 mg dL,1; similar to those obtained during combined Intralipid®/heparin infusion. Systemic haemodynamics were not affected by drug infusion. Conclusions, Present findings demonstrate a concentration-dependent increase in ocular and skin blood flow by FFA independently of elevated TG plasma concentrations. As vasodilation of resistance vessels occur rapidly, FFA may play a role in the development of continued regional hyperperfusion and deteriorate microvascular function. [source]


    Comparison of gingival blood flow during healing of simplified papilla preservation and modified Widman flap surgery: a clinical trial using laser Doppler flowmetry

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2007
    M. Retzepi
    Abstract Aim: This prospective randomized-controlled clinical trial compared the gingival blood flow responses following simplified papilla preservation (test) versus modified Widman flap (control). Materials and Methods: Twenty contra-lateral upper sites with pocket depth 5 mm after initial treatment in 10 chronic periodontitis patients were randomly assigned to either test or control treatment, using a split-mouth design. Laser Doppler flowmetry recordings were performed pre-operatively, following anaesthesia, immediately post-operatively and on days 1, 2, 3, 4, 7, 15, 30 and 60, at nine selected sites per flap. Results: Significant ischaemia was observed at all sites following anaesthesia and immediately post-operatively. At the mucosal flap basis, a peak hyperaemic response was observed on day 1, which tended to resolve by day 4 at the test sites, but persisted until day 7 at the control sites. The buccal and palatal papillae blood perfusion presented the maximum increase on day 7 in both groups and returned to baseline by day 15. Both surgical modalities yielded significant pocket depth reduction, recession increase and clinical attachment gain. Conclusions: Periodontal access flaps represent an ischaemia,reperfusion flap model. The simplified papilla preservation flap may be associated with faster recovery of the gingival blood flow post-operatively compared with the modified Widman flap. [source]


    Gingival blood flow changes following periodontal access flap surgery using laser Doppler flowmetry

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 5 2007
    M. Retzepi
    Abstract Aim: To investigate the pattern of gingival blood flow changes following periodontal access flap surgery by laser Doppler flowmetry (LDF). Material and methods: Fourteen patients with chronic periodontitis presenting upper anterior sites with pocket depth 5 mm after initial treatment were included in the study. Periodontal access flap surgery was performed on the experimental areas and LDF recordings were taken at baseline, following anaesthesia, immediately postoperatively and on days 1, 2, 3, 4, 7, 15, 30 and 60 of healing, at nine predetermined sites per flap. Results: Significant ischaemia was observed at all flap sites following anaesthesia and immediately postoperatively. At the alveolar mucosal sites, a peak increase of the gingival blood flow was observed on postoperative day 1 (p<0.001), which persisted until day 7 (p=0.012) and resolved by day 15. The mucosal sites close to the flap periphery presented higher blood perfusion compared with the sites located centrally in the flap. The microcirculatory perfusion of the buccal and palatal papillae was maximum on postoperative day 7 (p=0.013 and <0.001, respectively) and returned to baseline by day 15. Conclusion: Topographically distinct areas of the periodontal access flap consistently present different patterns of microvascular blood flow alterations during the wound-healing period. [source]


    Vasopressin decreases intestinal mucosal perfusion: a clinical study on cardiac surgery patients in vasodilatory shock

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2009
    A. NYGREN
    Background: Low to moderate doses of vasopressin have been used in the treatment of cathecholamine-dependent vasodilatory shock in sepsis or after cardiac surgery. We evaluated the effects of vasopressin on jejunal mucosal perfusion, gastric-arterial pCO2 gradient and the global splanchnic oxygen demand/supply relationship in patients with vasodilatory shock after cardiac surgery. Methods: Eight mechanically ventilated patients, dependent on norepinephrine to maintain mean arterial pressure (MAP) ,60 mmHg because of septic/post-cardiotomy vasodilatory shock and multiple organ failure after cardiac surgery, were included. Vasopressin was sequentially infused at 1.2, 2.4 and 4.8 U/h for 30-min periods. Norepinephrine was simultaneously decreased to maintain MAP at 75 mmHg. At each infusion rate of vasopressin, data on systemic hemodynamics, jejunal mucosal perfusion, jejunal mucosal hematocrit and red blood cell velocity (laser Doppler flowmetry) as well as gastric-arterial pCO2 gradient (gastric tonometry) and splanchnic oxygen and lactate extraction (hepatic vein catheter) were obtained. Results: The cardiac index, stroke volume index and systemic oxygen delivery decreased and systemic vascular resistance and systemic oxygen extraction increased significantly, while the heart rate or global oxygen consumption did not change with increasing vasopressin dose. Jejunal mucosal perfusion decreased and the arterial-gastric-mucosal pCO2 gradient increased, while splanchnic oxygen or lactate extraction or mixed venous,hepatic venous oxygen saturation gradient were not affected by increasing infusion rates of vasopressin. Conclusions: Infusion of low to moderate doses of vasopressin in patients with norepinephrine-dependent vasodilatory shock after cardiac surgery induces an intestinal and gastric mucosal vasoconstriction. [source]


    Patellar blood flow during knee arthroplasty surgical exposure: Intraoperative monitoring by laser doppler flowmetry

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 10 2007
    Axel Hempfing
    Abstract Patellofemoral complications following knee arthroplasty are a well-known problem. Patellar ischemia has been suspected to be causative for fracture, anterior knee pain, and patella component failure. The purpose of this study was to assess the influence of knee arthroplasty surgical dissection on patellar blood flow. Patellar blood flow was measured by means of intraosseous laser Doppler flowmetry (LDF) in 10 patients undergoing total knee arthroplasty by a standard medial parapatellar approach. The initial blood flow was 121.6,±,114.7 AU. The signal significantly decreased by 71% (p,=,0.0051) when the knee was flexed and lost the pulsatile signal pattern in 80%. After arthrotomy, the signal was 100.1,±,120.3 AU in extension. The lowest signal was found in flexion and eversion of the patella (mean, 18,±,10.7 AU) and all signals lost pulsatility. As compared to the initial values, completion of the soft tissue dissection did not lead to a significant change of the blood flow signal (121.3,±,104.8; p,=,0.6835). Flexion of the knee joint markedly reduced patellar perfusion. Standard medial parapatellar approach did not significantly change patellar blood flow. This study does not support the theory of postoperative patellar ischemia as a cause of anterior knee pain or patellofemoral problems. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1389,1394, 2007 [source]


    Microcirculatory Dysfunction in Chronic Venous Insufficiency (CVI)

    MICROCIRCULATION, Issue S1 2000
    MICHAEL JÜNGER
    ABSTRACT The elevated ambulatory pressure in the peripheral venous system of chronic venous insufficiency (CVI) patients manifests itself not only in the form of disturbed macrocirculation but also and particularly in microangiopathic changes. For this reason, it is closely correlated with trophic disorders of the skin and can ultimately lead to ulceration. Using microcirculation research techniques, we are able to provide clear evidence of a typical microangiopathy in chronic venous insufficiency. Fifty CVI patients in Widmer stages I, II, and III were examined with fluorescence video microscopy, intravital video capillaroscopy, transcutaneous oxygen partial pressure measurement, TcpO2 and laser Doppler flowmetry. The effects of compression therapy with individually fitted compression stockings on capillary morphology were studied over a period of 4 weeks in 20 CVI patients in Widmer stages I and II. The capillary pressure was measured during simulated muscle contraction using a servo-null micropressure system. We periodically drew blood from the dorsalis pedis vein and a brachial vein of 11 healthy test persons and 8 patients with stage III CVI during experimental venous hypertension in order to evaluate the expression pattern of leukocyte adhesion molecules involved in inflammation: LFA-1 (CD11a), Mac-1 (CD11b), p150,95 (CD11c), CD18, VLA-4 (CD49d), and L-selectin (CD62L). In the same patients, we used immunohistochemical methods to examine clinically unaffected skin and the skin near an ulcer, focusing on the adhesion molecules ICAM-1, VCAM-1, and E-selectin. The microangiopathic changes observed with worsening clinical symptoms include a decrease in the number of capillaries, glomerulus-like changes in capillary morphology, a drop in the oxygen content (tcpO2) of the skin, increased permeability of the capillaries to low-molecular-weight substances, increased laser Doppler flux reflecting elevated subcutaneous flow, and diminished vascular reserve. These microangiopathic changes worsen in linear proportion to the clinical severity of chronic venous insufficiency. In patients with venous ulcerations, the baseline expression of LFA-1 and VLA-4 on lymphocytes, Mac-1 expression on the myeloid cell line, and L-selectin expression on all three cell lines was not significantly different from that in healthy controls. During orthostatic stress, there was a significant reduction in the expression of L-selectin in blood cells collected at foot level in the controls (p = 0.002), but not in the patients. Clinical improvement by compression therapy was accompanied by an increase in the number of nutritive capillaries, while the diameter of the capillaries and the dermal papillae was reduced. When ulcers healed in a short period (<6 weeks), we observed a concomitant increase in the number of capillaries (p < 0.05). Microangiopathy appears before trophic disorders of the skin develop. Even trophically normal skin areas may have dilated nutritive capillaries, an early sign of disturbed skin perfusion. These changes represent a plausible explanation for the development and to recurrency tendency of venous ulcers. The reduced expression of lymphocytic L-selectin in healthy controls during the orthostatic stress test may be an indication that the cells are activated by venous stasis. Clinically effective therapeutic measures improve the impaired microcirculation of the skin in the ankle area. [source]


    Postoperative monitoring of free flaps in UK plastic surgery units

    MICROSURGERY, Issue 6 2005
    Ch.B. (Hons.), M.R.C.S. (Eng.), N. Jallali B.Sc.
    Monitoring free-tissue transfers in the postoperative period is valuable for detection of failing flaps. As well as conventional methods, a myriad of sophisticated techniques have been reported in the literature. Using a postal questionnaire, a survey was conducted to delineate current protocols employed in UK plastic surgery units. Data were received from 148 plastic surgeons in 51 units. All surgeons used clinical assessment, although there was significant disparity in the duration and frequency of postoperative monitoring. Adjuvant techniques such as laser Doppler flowmetry were routinely used by less than 20% of surgeons. We conclude that there is considerable variation in postoperative monitoring of free flaps, with significant clinical and resource implications. A protocol based on robust evidence is thus recommended. © 2005 Wiley-Liss, Inc. Microsurgery 25:469,472, 2005. [source]


    Characterization of autonomic dysfunction in patients with irritable bowel syndrome using fingertip blood flow

    NEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2008
    T. Tanaka
    Abstract, Fingertip blood flow (FTBF) as measured by laser Doppler flowmetry (LDF) measurement is considered an indicator of sympathetic nerve function. We evaluated autonomic function in patients with irritable bowel syndrome (IBS) by assessing FTBF with both LDF and continuous-wave (cw) Doppler sonography. Firstly, the two methods were compared in 40 healthy volunteers. Next, 59 patients with IBS as well as 118 healthy volunteer controls were studied. In the supine position, FTBF in the right index finger was measured with cw Doppler sonography, whereas FTBF in the left index finger was assessed with LDF. After baseline measurement for at least 5 min, the volunteers received sympathetic stimulation from cold stress applied without notification in the form of an icebag (0 °C) upon the left forearm for 1 min. The new cw Doppler sonography method can be used in place of the old LDF method for clinical purposes. FTBF velocity before stimulation (Vpre) was significantly lower in the IBS group than that in the healthy volunteers (P < 0.01). In addition, the time required for FTBF to return to Vpre after stimulation was significantly longer in the IBS group than that in the control group. (P = 0.02). Thus, measurement of FTBF with cw Doppler sonography can be useful in the assessment of sympathetic nerve function. The IBS patients showed an abnormal FTBF response suggesting the presence of excess sympathetic activity. [source]


    Role of Vascular Reflex in Nasal Mucosal Swelling in Nasal Allergy

    THE LARYNGOSCOPE, Issue 2 2000
    Tsutomu Numata MD
    Abstract Objective: In patients with nasal allergy, antigen challenge on the unilateral nasal mucosa results in nasal secretion not only in the ipsilateral but also in the contralateral nasal cavities that can be inhibited almost completely by premedication with atropine sulfate. The present study was performed to elucidate if centrally mediated vascular reflex induced by antigen challenge plays a role in nasal mucosal swelling in subjects with nasal allergy. Methods: Variations of mucosal swelling and mucosal blood flow in the ipsilateral and the contralateral nasal cavities after unilateral antigen challenge were evaluated by acoustic rhinometry and laser Doppler flowmetry in 20 patients with perennial nasal allergy. Results: Unilateral antigen challenge caused ipsilateral and contralateral nasal mucosal swelling in 17 and 13 patients, respectively. Incidence of contralateral nasal mucosal swelling after unilateral antigen challenge was significantly higher compared with that after control disc challenge (P < .001). In 10 patients in whom unilateral antigen challenge caused bilateral nasal mucosal swelling, significant swelling of the nasal mucosa lasted for more than 30 minutes in the ipsilateral nasal cavity after antigen challenge compared with only 15 minutes in the contralateral nasal cavity. Peak values of contralateral mucosal swelling were 45.3% of those of ipsilateral nasal mucosa. Conclusions: Centrally mediated vascular reflex is partially involved in the onset of nasal mucosal swelling observed after antigen challenge in subjects with nasal allergy. However, nasal mucosal swelling that persists and proceeds even 20 minutes after antigen challenge is caused by the direct effects of chemical mediators on the nasal vasculature. [source]


    The effect of a new topical local anaesthetic delivery system on forearm skin blood flow reactivity,

    ANAESTHESIA, Issue 2 2010
    M. D. Wiles
    Summary Different topical local anaesthetics have varying effects on skin blood flow and vascular reactivity. We compared the vasoactive properties of Rapydan®, a new topical local anaesthetic, with those of AmetopÔ and EMLAÔ creams in 20 healthy volunteers. Blood flow and vascular reactivity in the forearm skin were assessed by laser Doppler flowmetry and the transient hyperaemic response ratio respectively, before and after the application of EMLA (for 60 min), Ametop (for 30 and 60 min) and Rapydan (for 30 min). Application of EMLA had no effect on skin blood flow (median (IQR [range]) change from baseline ,0.9% (,63 to 414 [,38.5 to 51.3] %, p = 1.0)) or mean (SD) transient hyperaemic response ratio (from 2.86 (0.86) to 3.17 (1.3), p = 0.38). The application of Ametop for 60 min produced a greater median (IQR [range]) increase in blood flow from baseline (508 (,55 to 998 [148,649]) %) than Rapydan applied for 30 min 160 (,77 to 997 [45,301]) %, p = 0.001), and a similar decrease in mean (SD) transient hyperaemic response ratio (from 2.69 (1.16) to 1.08 (0.26) and from 2.83 (0.84) to 1.49 (0.93) respectively, p = 0.57). [source]


    IMPACT OF BLOOD FLOW OCCLUSION ON LIVER NECROSIS FOLLOWING THERMAL ABLATION

    ANZ JOURNAL OF SURGERY, Issue 1-2 2006
    Mehrdad Nikfarjam
    Background: Laser, radiofrequency and microwave are common techniques for local destruction of liver tumours by thermal ablation. The main limitation of thermal ablation treatment is the volume of necrosis that can be achieved. Blood flow occlusion is commonly advocated as an adjunct to thermal ablation to increase the volume of tissue necrosis based on macroscopic and histological assessment of immediate or direct thermal injury. This study examines the impact of blood flow occlusion on direct and indirect laser induced thermal liver injury in a murine model using histochemical methods to assess tissue vitality. Methods: Thermal ablation produced by neodymium yttrium-aluminium-garnet laser (wavelength 1064 nm) was applied to the liver of inbred male CBA strain mice at 2 W for 50 s (100 J). Treatment was performed with and without temporary portal vein and hepatic artery blood flow occlusion. Animals were killed upon completion of the procedure to assess direct thermal injury or at 24, 48 and 72 h to assess the progression of tissue damage. The maximum diameter of necrosis was assessed by vital staining for nicotinamide adenine dinucleotide (NADH) diaphorase. Microvascular changes were assessed by laser Doppler flowmetry, confocal in vivo microscopy and scanning electron microscopy. Results: The direct thermal injury (mean SE) assessed by NADH diaphorase staining was significantly greater following thermal ablation treatment without blood flow occlusion than with blood flow occlusion (3.3 (0.4) mm vs 2.9 (0.3) mm; P = 0.005). Tissue disruption, cracking and vacuolization was more pronounced adjacent to the fibre insertion site in the group treated with thermal ablation combined with blood flow occlusion. There was an equivalent increase in the extent of injury following therapy in both groups that reached a peak at 48 h. The maximum diameter of necrosis in the thermal ablation alone group at 48 h was significantly greater than the thermal ablation combined with blood flow occlusion group (5.8 (0.4) mm vs 5.3 (0.3) mm; P = 0.011). The patterns of microvascular injury were similar in both groups, varying in extent. Conclusion: Temporary blood flow inflow occlusion appears to decrease the extent of initial injury measured by vital staining techniques and does not alter the time sequence of progressive tissue injury following thermal ablation therapy. [source]


    Effect of topical glyceryl trinitrate on anodermal blood flow in patients with chronic anal fissures

    ANZ JOURNAL OF SURGERY, Issue 9 2001
    Keith B. Kua
    Introduction: Recent studies have highlighted the role of increased internal anal sphincter pressure and decreased anodermal blood flow in the pathogenesis of chronic anal fissures. The duration of the effect of topical 0.2% glyceryl trinitrate (GTN) ointment on anodermal blood flow in fissure and normal areas was investigated in patients with chronic anal fissures. Methods: Six patients with chronic anal fissures in the posterior midline participated in the study. Blood flow measurements were performed on the anoderm using laser Doppler flowmetry before and immediately after the topical application of 0.2% GTN ointment and subsequent readings were taken at 5, 15, 30, 45 and 60 min in all four quadrants. Results: The mean anodermal blood flow in the fissure region is significantly lower than the mean blood flow of the rest of the anoderm before 0.2% GTN ointment is applied (228.7 ± 61.8 flux units vs 439.3 ± 25.5 flux units, respectively; P < 0.05). Immediately after the application of local 0.2% GTN ointment there is a significant increase in anodermal blood flow over the anal fissure region (457.8 ± 56.5 flux units; P < 0.05) compared to the rest of the anoderm (457.4 ± 30.8 flux units). This increase is most marked at 5 min post-GTN ointment application in the fissure area (474.6 ± 41.1 flux units) and the blood flow in the fissure region is consistently above the rest of the anoderm for most of the 60 min. Conclusion: There is clearly reduced blood flow to the chronic anal fissure region compared to the rest of the anoderm. Topical application of glyceryl trinitrate ointment seems to significantly improve the blood flow to the fissured area in the first hour. This may therefore help in the healing of chronic anal fissures. [source]


    Tumour growth following portal branch ligation in an experimental model of liver metastases,

    BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 6 2010
    O. Kollmar
    Background: Portal branch ligation (PBL) is being used increasingly before hepatectomy for colorectal metastases. This study evaluated the effect of PBL on angiogenesis, growth factor expression and tumour growth in a mouse model of hepatic colorectal metastases. Methods: CT26.WT cells were implanted into the left liver lobe of BALB/c mice. Animals underwent PBL of the left liver lobe or sham treatment. Angiogenesis, microcirculation, growth factor expression, cell proliferation and tumour growth were studied over 14 and 21 days by intravital multifluorescence microscopy, laser Doppler flowmetry, immunohistochemistry and western blotting. Results: Left hilar blood flow and tumour microcirculation were significantly diminished during the first 7 days after PBL. This resulted in tumour volume being 20 per cent less than in sham controls by day 14. Subsequently, PBL-treated animals demonstrated recovery of left hilar blood flow and increased expression of hepatocyte growth factor and transforming growth factor ,, associated with increased cell proliferation and acceleration of growth by day 21. Conclusion: PBL initially reduced vascular perfusion and tumour growth, but this was followed by increased growth factor expression and cell proliferation. This resulted in delayed acceleration of tumour growth, which might explain the stimulated tumour growth observed occasionally after PBL. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]


    Review Article: Ocular blood flow assessment using continuous laser Doppler flowmetry

    ACTA OPHTHALMOLOGICA, Issue 6 2010
    Charles E. Riva
    Acta Ophthalmol. 2010: 88: 622,629 Abstract. This article describes the technique of continuous laser Doppler flowmetry (LDF) as applied to the measurement of the flux of red blood cells in the optic nerve head, iris and subfoveal choroid. Starting with the exposition of the physical principles underlying LDF, we first describe the various devices developed to perform LDF in these vascular beds. We then discuss the clinical protocols, blood flow parameters, calibration procedures, reproducibility and limitations of the LDF technique. Various problems still need to be solved in order to bring to light the full potential of LDF in the assessment of microcirculatory haemodynamics. [source]


    2421: Wall-to-lumen ratio of retinal vessels in patients with cerebrovascular damage

    ACTA OPHTHALMOLOGICA, Issue 2010
    G MICHELSON
    Purpose There is evidence that generalized retinal arteriolar narrowing, which can be measured by the arteriole-to-venule ratio (AVR) of retinal vessels, predicts cerebrovascular events. The wall-to-lumen ratio (WLR) and wall cross-sectional area (WCSA) of retinal arterioles reflect structural arteriolar parameters. The primary objective was to test the association between WLR and AVR in patients with cerebrovascular damage. Methods In this cross-sectional study, 23 patients (57.5 +/- 9.4 years) with acute transitory ischemic attack or lacunar cerebral infarct were compared with two age-matched control groups: 83 subjects with essential hypertension (53.7 +/- 5.5 years) and 16 normotensive subjects (52.2 +/- 8.3 years). Retinal arteriolar parameters (WLR, WTH, and WCSA) were assessed in vivo with scanning laser Doppler flowmetry (SLDF). AVR and a qualitative evaluation of retinal vessels were obtained from digital retinal color photographs. The intima-media thickness (IMT) of the carotid artery was measured. Results WLR (0.44 +/- 0.1 vs. 0.34 +/- 0.1 vs. 0.30 +/- 0.1, P < 0.001) and carotid IMT (P < 0.05) were significantly greater in the cerebrovascular event group compared with normotensive subjects. WLR and WCSA were significantly higher in the cerebrovascular event group compared with subjects with mild arterial hypertension. AVR was similar in all three study groups. Conclusion The increase in WLR and WCSA of retinal arterioles, as well as in IMT in patients with cerebrovascular damage suggests vascular hypertrophy in the microvascular and macrovascular bed. The lack of association between AVR of retinal vessels and WLR of retinal arterioles [source]


    2221: Gases and the ocular vasculature

    ACTA OPHTHALMOLOGICA, Issue 2010
    L SCHMETTERER
    Purpose The regulation of ocular blood flow and oxygenation is largely controlled by metabolic factors. Among them gases like oxygen (O2), carbon dioxide (CO2), carbon monoxide (CO) and nitroc oxide (NO) play a key role. Methods In a series of clinical trials we focussed on the role of O2, CO2, CO and NO in the control of ocular blood flow. These studies were done on healthy subjects and employed a number of techniques including laser Doppler flowmetry, color Doppler imaging and pulsatile ocular blood flow techniques. Results O2 is a very potent vasoconstrictor in the retina and optic nerve head, but not in the choroid. The mechanisms underlying this effect is not entirely clear, but appears to involve endothelin A receptors. CO and CO2 are potent vasodilators in retina, choroid and optic nerve head. NO plays a major role in the control of basal vascular tone in all ocular vessels, but is also involved in many agonist-induced vasodilator effects. Conclusion Gases play a key role in controlling ocular blood flow. An imblanace of the production of these mediators is associated with ischemia, hypoxia and endothelial dysfunction. [source]


    2323: Role of nitric oxide in optic nerve head blood flow regulation during isometric exercise in healthy humans

    ACTA OPHTHALMOLOGICA, Issue 2010
    D SCHMIDL
    Purpose Nitric oxide (NO) is an important regulator of optic nerve head (ONH) blood flow in humans. We have previously shown that NO is also involved in choroidal blood flow regulation during isometric exercise. Inhibition of NO synthase (NOS) has been reported to shift choroidal pressure,flow curves during squatting to the right. The hypothesis for the present study was that inhibition of NOS may also influence ONH blood flow during isometric exercise. Methods To test this hypothesis, a randomized, double-masked, placebo-controlled, three-way crossover study was performed in 18 healthy volunteers. Subjects received on different study days intravenous infusions of NG-monomethyl- L-arginine (L-NMMA), phenylephrine, or placebo. During these infusion periods, subjects were asked to squat for 6 minutes. ONH blood flow was assessed with laser Doppler flowmetry, and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure. Results L-NMMA and phenylephrine increased resting OPP (p < 0.001 versus baseline), but only L-NMMA reduced resting ONH blood flow (p = 0.02 versus baseline). The relative increase in OPP during isometric exercise was comparable with all drugs administered (p = 0.69). In addition, the change of ONH blood flow was comparable with all administered drugs (p = 0.43). Conclusion These data indicate that NO plays an important role in the regulation of ONH blood flow at baseline, but does not change the response of ONH blood flow during isometric exercise. [source]


    Twelve-hour reproducibility of retinal and optic nerve blood flow parameters in healthy individuals

    ACTA OPHTHALMOLOGICA, Issue 8 2009
    Alexandra Luksch
    Abstract. Purpose:, The aim of the present study was to investigate the reproducibility and potential diurnal variation of optic nerve head and retinal blood flow parameters in healthy individuals over a period of 12 hr. Methods:, We measured optic nerve head and retinal blood flow parameters in 16 healthy male non-smoking individuals at five time-points during the day (08:00, 11:00, 14:00, 17:00 and 20:00 hr). Outcome parameters were perimacular white blood cell flux (as assessed with the blue field entoptic technique), blood velocities in retinal veins (as assessed with bi-directional laser Doppler velocimetry), retinal arterial and venous diameters (as assessed with the retinal vessel analyser), optic nerve head blood flow, volume and velocity (as assessed with single point and scanning laser Doppler flowmetry) and blood velocities in the central retinal artery (as assessed with colour Doppler imaging). The coefficient of variation and the maximum change from baseline in an individual were calculated for each outcome parameter. Results:, No diurnal variation in optic nerve head or retinal blood flow was observed with any of the techniques employed. Coefficients of variation were between 1.6% and 18.5% for all outcome parameters. The maximum change from baseline in an individual was much higher, ranging from 3.7% to 78.2%. Conclusion:, Our data indicate that in healthy individuals the selected techniques provide adequate reproducibility to be used in clinical studies. However, in patients with eye diseases and reduced vision the reproducibility may be considerably worse. [source]


    Effect of systemic moxaverine on ocular blood flow in humans

    ACTA OPHTHALMOLOGICA, Issue 7 2009
    Hemma Resch
    Abstract. Purpose:, A number of common eye diseases are associated with ocular perfusion abnormalities. The present study aimed to investigate whether systemically administered moxaverine improves ocular blood flow. Methods:, Sixteen healthy volunteers were studied in this randomized, double-masked, placebo-controlled, two-way crossover study. Moxaverine in a dose of 150 mg was administered i.v. Ocular haemodynamic parameters were measured before and after drug administration. Retinal arterial and venous diameters were measured with a retinal vessel analyser. Retinal blood velocity was assessed using laser Doppler velocimetry and choroidal and optic nerve head blood flow was measured with laser Doppler flowmetry. Results:, Moxaverine increased choroidal blood flow (22.6 ± 27.9%), an effect which was significant versus placebo (p = 0.015). Red blood cell velocity in retinal veins tended to increase by 13.6 ± 13.3% after infusion of moxaverine, but this effect was not significant compared with placebo (p = 0.25). In the optic nerve head moxaverine also tended to increase blood flow (11.8 ± 12.7%), but, again, this effect was not significant versus placebo (p = 0.12). Neither moxaverine nor placebo had an effect on retinal arterial diameters. In retinal veins moxaverine tended to induce vasodilation (2.6 ± 2.8%) and to increase blood flow (19.6 ± 16.5%), but these effects were not significant (both p = 0.12). Conclusions:, The present study indicates an increase in choroidal blood flow after systemic infusion of a single dose of moxaverine in healthy subjects. Further studies are warranted to investigate whether these effects are also seen after longterm treatment in patients with ocular vascular disease. [source]