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Michael J Griffin - One of the best experts on this subject based on the ideXlab platform.
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reductions in Finger Blood Flow induced by 125 hz vibration effect of location of contact with vibration
International Archives of Occupational and Environmental Health, 2016Co-Authors: Michael J GriffinAbstract:Purpose This study investigated whether the reductions in Finger Blood Flow induced by 125-Hz vibration applied to different locations on the hand depend on thresholds for perceiving vibration at these locations.
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reduction in Finger Blood Flow induced by hand transmitted vibration effect of hand elevation
International Archives of Occupational and Environmental Health, 2015Co-Authors: Marcella Mauro, Massimo Bovenzi, Michael J GriffinAbstract:This study investigated the effect of hand elevation on reductions in Finger Blood Flow (FBF) induced by hand-transmitted vibration. Fourteen males attended six sessions on six separate days, with a control sessions and a vibration session (125-Hz vibration at 44 ms−2 rms) with the right hand supported at each of three elevations: 20 cm below heart level (HL), at HL, and 20 cm above HL. Finger Blood Flow on the left and right hand was measured every 30 s during each 25-min session comprised of five periods: (1) no force and no vibration (5 min), (2) 2-N force and no vibration (5 min), (3) 2-N force and vibration (5 min), (4) 2-N force and no vibration (5 min), and (5) no force and no vibration (5 min). Without vibration, FBF decreased with increasing elevation of the hand. During vibration of the right hand, FBF reduced on both hands. With elevation of the right hand, the percentage reduction in FBF due to vibration (relative to FBF on the same Finger at the same elevation before exposure to vibration) was similar on the middle and little Fingers of both hands. After cessation of vibration, there was delayed return of FBF with all three hand heights. Vibration of one hand reduces FBF on both exposed and unexposed hands, with the reduction dependent on the elevation of the hand. The mechanisms responsible for vibration-induced reductions in FBF seem to reduce Blood Flow as a percentage of the Blood Flow without vibration. Tasks requiring the elevation of the hands will be associated with lower FBF, and the FBF will be reduced further if there is exposure to hand-transmitted vibration.
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relation between vibrotactile perception thresholds and reductions in Finger Blood Flow induced by vibration of the hand at frequencies in the range 8 250 hz
European Journal of Applied Physiology, 2014Co-Authors: Michael J GriffinAbstract:This study investigated how the vasoconstriction induced by vibration depends on the frequency of vibration when the vibration magnitude is defined by individual thresholds for perceiving vibration [i.e. sensation levels (SL)]. Fourteen healthy subjects attended the laboratory on seven occasions: for six vibration frequencies (8, 16, 31.5, 63, 125, or 250 Hz) and a static control condition. Finger Blood Flow (FBF) was measured in the middle Fingers of both hands at 30-second intervals during five successive periods: (i) no force or vibration, (ii) 2-N force, no vibration, (iii) 2-N force, vibration, (iv) 2-N force, no vibration, (v) no force or vibration. During period (iii), vibration was applied to the right thenar eminence via a 6-mm diameter probe during ten successive 3-min periods as the vibration magnitude increased in ten steps (−10 to +40 dB SL). With vibration at 63, 125, and 250 Hz, there was vasoconstriction on both hands when the vibration magnitude reached 10 dB SL. With vibration at 8, 16, and 31.5 Hz, there was no significant vasoconstriction until the vibration reached 25 dB SL. At all frequencies, there was greater vasoconstriction with greater magnitudes of vibration. It is concluded that at the higher frequencies (63, 125, and 250 Hz), the Pacinian channel mediates vibrotactile sensations near threshold and vasoconstriction occurs when vibration is perceptible. At lower frequencies (8, 16, and 31.5 Hz), the Pacinian channel does not mediate sensations near threshold and vasoconstriction commences at greater magnitudes when the Pacinian channel is activated.
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reductions in Finger Blood Flow induced by 125 hz vibration effect of area of contact with vibration
European Journal of Applied Physiology, 2013Co-Authors: Michael J GriffinAbstract:To investigate whether the Pacinian channel is involved in vibration-induced reductions of Finger Blood Flow (FBF), vibrotactile thresholds and vasoconstriction have been studied with 125-Hz vibration and two contact areas: 3- or 6-mm-diameter vibrating probes with 2-mm gaps to fixed surrounds. Fifteen subjects provided thresholds for perceiving vibration at the thenar eminence of the right hand with both contact areas. With both contact areas, FBF was then measured in the middle Fingers of both hands during five successive 5-min periods: (i) no force and no vibration, (ii) force and no vibration, (iii) force with vibration 15 dB above threshold, (iv) force and no vibration, and (v) no force and no vibration. Thresholds were in the ranges of 0.16–0.66 ms−2 r.m.s. (6-mm probe) and 0.32–1.62 ms−2 r.m.s. (3-mm probe). With the magnitude of vibration 15 dB above each individual’s threshold with the 3-mm probe, the median reduction in FBF with the 6-mm probe (to 70 and 77 % of pre-exposure FBF on the exposed right hand and the unexposed left hand, respectively) was greater than with the 3-mm probe (79 and 85 %). There were similar reductions in FBF when vibration was presented by the two contactors at the same sensation level (i.e. 15 dB above threshold with each probe). The findings are consistent with reductions in FBF arising from excitation of the Pacinian channel: increasing the area excited by vibration increases Pacinian activation and provokes stronger perception of vibration and greater vasoconstriction.
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acute effects of mechanical shocks on Finger Blood Flow influence of shock repetition rate and shock magnitude
International Archives of Occupational and Environmental Health, 2012Co-Authors: Marcella Mauro, Massimo Bovenzi, Michael J GriffinAbstract:Finger Blood Flow is reduced by hand-transmitted vibration but there has been little study of the peripheral vascular response to repetitive mechanical shocks. This study investigated how reductions in Finger Blood Flow depend on shock repetition rate and the peak and rms magnitude of acceleration. Subjects attended seven sessions: six with repetitive mechanical shocks and a control session with no shocks. Each session comprised five successive 5-min periods: (1) no force and no vibration, (2) force and no vibration, (3) force and vibration, (4) force and no vibration and (5) no force and no vibration. During the second–fourth periods, the palm of the right hand applied 2-N force to a vibrator. During the third period, a 125-Hz mechanical shock was applied with one of four repetition rates (1.3, 5.3, 21 or 83.3/s) and one of three acceleration magnitudes (2.5, 5 or 10 ms−2 rms, unweighted). Finger Blood Flow was measured every 30 s in the middle and little Fingers of the right (exposed) hand and the left (unexposed) hand. Different repetition rates (1.3–83.3 s−1) and different peak magnitudes (10–88 ms−2 peak) but the same rms acceleration (10 ms−2 rms) caused similar decreases in Blood Flow in Fingers on exposed and unexposed hands. Shocks with a 83.3 s−1 repetition rate, peak magnitude of 10 ms−2 and rms acceleration of 10 ms−2 provoked greater reduction in Finger Blood Flow than shocks with the same peak magnitude but lower repetition rate (21 or 5.3 s−1) and lower rms acceleration (5 or 2.5 ms−2). For shocks similar to those based on 125-Hz oscillations with repetition rates between 1.3 and 83.3 s−1, acute reductions in Finger Blood Flow can be predicted from the rms acceleration.
Maria Samara - One of the best experts on this subject based on the ideXlab platform.
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Successful Intravenous Regional Sympathetic Blockade (Bier’s Block) with Guanethidine and Lidocaine in a Patient with Advanced Buerger’s Disease (Thromboangiitis Obliterans)
2016Co-Authors: Kosmas I Paraskevas, Aikaterini A Trigka, Maria SamaraAbstract:A 65-year-old man, a heavy smoker with Buerger’s disease (thromboangiitis obliterans), presented to this department with persistent severe ischemic rest pain at the Fingers of his right hand, not responding to oral treatment with vasodilators and analgesics. Critical Blood Flow was discovered in the middle, ring, and little Finger, with ischemic ulcerations apparent in the Fingertips of these 3 Fingers. The distal phalanx of the little Finger had been amputated 6 months before because of gangrenous necrosis. In an attempt to avoid further disabling ampu-tations, the patient received 3 series of Bier’s block sessions with guanethidine and lidocaine according to a specific protocol. Marked increase in Finger Blood Flow was induced even after the first series, and complete disappearance of both Fingertip ulcerations and ischemic rest pain was achieved. No side effects were observed. The above-described method in a patient with advanced Buerger’s disease resulted in excellent pain relief and full restoration of both Blood Flow and function of the affected Fingers
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successful intravenous regional sympathetic blockade bier s block with guanethidine and lidocaine in a patient with advanced buerger s disease thromboangiitis obliterans a case report
Angiology, 2005Co-Authors: Kosmas I Paraskevas, Aikaterini A Trigka, Maria SamaraAbstract:A 65-year-old man, a heavy smoker with Buerger's disease (thromboangiitis obliterans), presented to this department with persistent severe ischemic rest pain at the Fingers of his right hand, not responding to oral treatment with vasodilators and analgesics. Critical Blood Flow was discovered in the middle, ring, and little Finger, with ischemic ulcerations apparent in the Fingertips of these 3 Fingers. The distal phalanx of the little Finger had been amputated 6 months before because of gangrenous necrosis. In an attempt to avoid further disabling amputations, the patient received 3 series of Bier's block sessions with guanethidine and lidocaine according to a specific protocol. Marked increase in Finger Blood Flow was induced even after the first series, and complete disappearance of both Fingertip ulcerations and ischemic rest pain was achieved. No side effects were observed. The above-described method in a patient with advanced Buerger's disease resulted in excellent pain relief and full restoration of both Blood Flow and function of the affected Fingers.
Kosmas I Paraskevas - One of the best experts on this subject based on the ideXlab platform.
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Successful Intravenous Regional Sympathetic Blockade (Bier’s Block) with Guanethidine and Lidocaine in a Patient with Advanced Buerger’s Disease (Thromboangiitis Obliterans)
2016Co-Authors: Kosmas I Paraskevas, Aikaterini A Trigka, Maria SamaraAbstract:A 65-year-old man, a heavy smoker with Buerger’s disease (thromboangiitis obliterans), presented to this department with persistent severe ischemic rest pain at the Fingers of his right hand, not responding to oral treatment with vasodilators and analgesics. Critical Blood Flow was discovered in the middle, ring, and little Finger, with ischemic ulcerations apparent in the Fingertips of these 3 Fingers. The distal phalanx of the little Finger had been amputated 6 months before because of gangrenous necrosis. In an attempt to avoid further disabling ampu-tations, the patient received 3 series of Bier’s block sessions with guanethidine and lidocaine according to a specific protocol. Marked increase in Finger Blood Flow was induced even after the first series, and complete disappearance of both Fingertip ulcerations and ischemic rest pain was achieved. No side effects were observed. The above-described method in a patient with advanced Buerger’s disease resulted in excellent pain relief and full restoration of both Blood Flow and function of the affected Fingers
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successful intravenous regional sympathetic blockade bier s block with guanethidine and lidocaine in a patient with advanced buerger s disease thromboangiitis obliterans a case report
Angiology, 2005Co-Authors: Kosmas I Paraskevas, Aikaterini A Trigka, Maria SamaraAbstract:A 65-year-old man, a heavy smoker with Buerger's disease (thromboangiitis obliterans), presented to this department with persistent severe ischemic rest pain at the Fingers of his right hand, not responding to oral treatment with vasodilators and analgesics. Critical Blood Flow was discovered in the middle, ring, and little Finger, with ischemic ulcerations apparent in the Fingertips of these 3 Fingers. The distal phalanx of the little Finger had been amputated 6 months before because of gangrenous necrosis. In an attempt to avoid further disabling amputations, the patient received 3 series of Bier's block sessions with guanethidine and lidocaine according to a specific protocol. Marked increase in Finger Blood Flow was induced even after the first series, and complete disappearance of both Fingertip ulcerations and ischemic rest pain was achieved. No side effects were observed. The above-described method in a patient with advanced Buerger's disease resulted in excellent pain relief and full restoration of both Blood Flow and function of the affected Fingers.
Aikaterini A Trigka - One of the best experts on this subject based on the ideXlab platform.
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Successful Intravenous Regional Sympathetic Blockade (Bier’s Block) with Guanethidine and Lidocaine in a Patient with Advanced Buerger’s Disease (Thromboangiitis Obliterans)
2016Co-Authors: Kosmas I Paraskevas, Aikaterini A Trigka, Maria SamaraAbstract:A 65-year-old man, a heavy smoker with Buerger’s disease (thromboangiitis obliterans), presented to this department with persistent severe ischemic rest pain at the Fingers of his right hand, not responding to oral treatment with vasodilators and analgesics. Critical Blood Flow was discovered in the middle, ring, and little Finger, with ischemic ulcerations apparent in the Fingertips of these 3 Fingers. The distal phalanx of the little Finger had been amputated 6 months before because of gangrenous necrosis. In an attempt to avoid further disabling ampu-tations, the patient received 3 series of Bier’s block sessions with guanethidine and lidocaine according to a specific protocol. Marked increase in Finger Blood Flow was induced even after the first series, and complete disappearance of both Fingertip ulcerations and ischemic rest pain was achieved. No side effects were observed. The above-described method in a patient with advanced Buerger’s disease resulted in excellent pain relief and full restoration of both Blood Flow and function of the affected Fingers
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successful intravenous regional sympathetic blockade bier s block with guanethidine and lidocaine in a patient with advanced buerger s disease thromboangiitis obliterans a case report
Angiology, 2005Co-Authors: Kosmas I Paraskevas, Aikaterini A Trigka, Maria SamaraAbstract:A 65-year-old man, a heavy smoker with Buerger's disease (thromboangiitis obliterans), presented to this department with persistent severe ischemic rest pain at the Fingers of his right hand, not responding to oral treatment with vasodilators and analgesics. Critical Blood Flow was discovered in the middle, ring, and little Finger, with ischemic ulcerations apparent in the Fingertips of these 3 Fingers. The distal phalanx of the little Finger had been amputated 6 months before because of gangrenous necrosis. In an attempt to avoid further disabling amputations, the patient received 3 series of Bier's block sessions with guanethidine and lidocaine according to a specific protocol. Marked increase in Finger Blood Flow was induced even after the first series, and complete disappearance of both Fingertip ulcerations and ischemic rest pain was achieved. No side effects were observed. The above-described method in a patient with advanced Buerger's disease resulted in excellent pain relief and full restoration of both Blood Flow and function of the affected Fingers.
Stephen S Cheung - One of the best experts on this subject based on the ideXlab platform.
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dynamic adaptation of the peripheral circulation to cold exposure
Microcirculation, 2012Co-Authors: Stephen S Cheung, H A M DaanenAbstract:Humans residing or working in cold environments exhibit a stronger cold-induced vasodilation (CIVD) reaction in the peripheral microvasculature than those living in warm regions of the world, leading to a general assumption that thermal responses to local cold exposure can be systematically improved by natural acclimatization or specific acclimation. However, it remains unclear whether this improved tolerance is actually due to systematic acclimatization, or alternately due to the genetic predisposition or self-selection for such occupations. Longitudinal studies of repeated extremity exposure to cold demonstrate only ambiguous adaptive responses. In field studies, general cold acclimation may lead to increased sympathetic activity that results in reduced Finger Blood Flow. Laboratory studies offer more control over confounding parameters, but in most studies, no consistent changes in peripheral Blood Flow occur even after repeated exposure for several weeks. Most studies are performed on a limited amount of subjects only, and the variability of the CIVD response demands more subjects to obtain significant results. This review systematically surveys the trainability of CIVD, concluding that repeated local cold exposure does not alter circulatory dynamics in the peripheries, and that humans remain at risk of cold injuries even after extended stays in cold environments.
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a novel model to predict cutaneous Finger Blood Flow via Finger and rectal temperatures
Microcirculation, 2011Co-Authors: Andres E Carrillo, Stephen S Cheung, Andreas D FlourisAbstract:Please cite this paper as: Carrillo, Cheung, and Flouris (2011). A Novel Model to Predict Cutaneous Finger Blood Flow Via Finger and Rectal Temperatures. Microcirculation18(8), 670–676. Abstract Objectives: To generate a model that predicts Fingertip Blood Flow (BFf) and to cross-validate it in another group of subjects. Methods: We used Fingertip temperature (Tf), forearm temperature minus Tf (TFor-f), rectal temperature (Tre), and their changes across time (lagT) to estimate BFf. Ten participants (six male, four female) were randomly divided into “model” and “validation” groups. We employed a passive hot–cold water immersion protocol during which each participant’s core temperature increased and decreased by 0.5°C above/below baseline during hot/cold conditions, respectively. A hierarchical multiple linear regression analysis was introduced to generate models using temperature indicators and lagT (independent variables) obtained from the model group to predict BFf (dependent variable). Results: Mean BFf (109.5 ± 158.2 PU) and predicted BFf (P-BFf) (111.4 ± 136.7 PU) in the model group calculated using the strongest (R2 = 0.766, p < 0.001) prediction model [P-BFf =Tf× 19.930 + lag4Tf × 74.766 + lag4Tre × 124.255 – 447.474] were similar (p = 0.6) and correlated (r = 0.880, p < 0.001). Autoregressive integrated moving average time-series analyses demonstrated a significant association between P-BFf and BFf (R2 = 0.381; Ljung–Box statistic = 8.097; p < 0.001) in the validation group. Conclusions: We provide a model that predicts BFf via two practical temperature indicators that can be implemented in both clinical and field settings.
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thermal basis of Finger Blood Flow adaptations during abrupt perturbations in thermal homeostasis
Microcirculation, 2011Co-Authors: Andreas D Flouris, Stephen S CheungAbstract:Please cite this paper as: Flouris and Cheung (2011). Thermal Basis of Finger Blood Flow Adaptations During Abrupt Perturbations in Thermal Homeostasis. Microcirculation18(1), 56–62. Abstract The objective of this experiment was to assess whether reflex alterations in Finger Blood Flow during repetitive hot and cold water immersion are associated with changes in rectal, tympanic, mean body temperature or heat storage. Fifteen healthy adults (eight males) volunteered. Following a 15-minute baseline period, participants were immersed in 42°C water and passively rested until their rectal temperature was raised by 0.5°C above baseline. Thereafter, they were immersed in a different water tank maintained at 12°C water temperature until their rectal temperature was decreased by 0.5°C below baseline. This procedure was conducted twice. Auto-Regressive Integrated Moving Average analysis showed that fluctuations in Finger Blood Flow were associated with changes in mean body temperature (Ljung-Box statistic >0.05; R2 = 0.67) and body heat storage (Ljung-Box statistic >0.05; R2 = 0.70), but not with rectal (Ljung-Box statistic <0.05; R2 = 0.54) or tympanic (Ljung-Box statistic <0.05; R2 = 0.49) temperatures. It is concluded that reflex alterations in Finger Blood Flow during repetitive hot and cold water immersions are associated with mean body temperature and the rate of body heat storage, but not with rectal and tympanic temperatures.