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PubMed1996

Difference between proximal and distal right coronary flow velocity pattern in humans.

The purpose of this study is to clarify the difference between proximal and distal right coronary artery flow velocity pattern in humans. Each portion of the coronary artery in thirteen patients with chest pain syndrome was measured by means of Doppler guide wire. The systolic/diastolic peak velocity ratio and velocity integral ratio at the proximal portion of the right coronary artery were significantly higher than those at distal portion of the right coronary artery (0.97 +/- 0.27, 0.61 +/- 0.20, 0.66 +/- 0.19, 0.44 +/- 0.13, respectively). In the right ventricular branch, coronary flow velocity pattern showed systolic dominancy. Systolic/diastolic peak velocity ratio and integral ratio showed 1.69 +/- 0.62 and 1.00 +/- 0.62 in the right ventricular branch, respectively. It is speculated that the less marked diastolic predominant pattern in the proximal right coronary artery flow velocity may be due to the fact that the proximal right coronary artery supplies both the right and left ventricle but that the distal right coronary artery supplies only the left ventricular inferior wall.

Aged↗
PubMed1997

Utility of Doppler-detectable microbubbles in the diagnosis and treatment of decompression sickness.

BACKGROUND: Doppler-detectable microbubbles (DMB) are frequently used to evaluate altitude decompression stress. However, the role of DMB in the therapy of decompression sickness (DCS) has not been examined. HYPOTHESIS: The ability of Doppler to detect microbubbles during decompression (Doppler test) may be used in the diagnosis of DCS, and to aid clinical decisions about treatment options for DCS. METHODS: We examined the data on DMB and symptoms from NASA Database on DCS (n = 516). The accuracy of Doppler test was obtained from the Receiver Operating Characteristic (ROC) for DMB (grades I through IV), and efficacy was obtained by calculating predictive or post-test probabilities. Threshold analysis was used to obtain the probabilities for testing and/or treatment decisions. RESULTS: The Doppler test was useful for both screening and confirming DCS, when different criteria (grade I for screening; grade IV for confirming) were used for a positive test. Calculation of predictive values and threshold analysis showed that: 1) early recompression was the therapy of choice when post-test probability of disease was > 0.25 in individuals with non-specific pain at altitude, and early recompression with 100% oxygen for 2 h at site level was optimal therapy when this probability was > 0.33; 2) hyperbaric therapy was optimal when post-test probability was > 0.04 in individuals with uncertain symptoms post-flight. CONCLUSIONS: The Doppler test was of greater utility in excluding DCS than confirming its presence, and was useful in making therapeutic decisions on DCS when confronted with non-specific symptoms at altitude.

Aerospace Medicine↗
PubMed1997

The effect of hyperbaric oxygen therapy on a burn wound model in human volunteers.

A previous nonblinded study has suggested beneficial effects from hyperbaric oxygen treatment of superficial partial-thickness radiation burns in human volunteers. This protocol was designed to either confirm or challenge these previous findings in a randomized, blinded format. Twelve healthy, nonsmoking volunteers (7 males, 5 females) participated. All were screened for contraindications to hyperbaric oxygen therapy (acute sinusitis, otitis media, pneumonia, pregnancy, active cancer, pneumothorax) and given a single test hyperbaric exposure. A standardized wound model was employed for the painless creation of a volar forearm lesion on volunteers by applying a suction device to form a blister, excising its epidermal roof, and irradiating the exposed dermis with ultraviolet light. Subjects were randomized into either a hyperbaric oxygen group (100% oxygen at 2.4 ATA, n = 6) or the sea-level air-breathing equivalent control group (8.75% oxygen at 2.4 ATA, n = 6). Both groups then underwent standard hyperbaric therapy. The subjects, the hyperbaric oxygen chamber operators, and the monitoring clinicians were all blinded to the oxygen concentration administered. Each subject received two dives per day over a 3-day period. The wounds were studied noninvasively prior to treatment and once per day over 6 days for size, hyperemia, and exudation, with epithelialization as the endpoint. The averages for each measurement of the hyperbaric oxygen group versus the control group were computed by means of a one-tail t test; p was considered significant at less than 0.05. Daily wound size, hyperemia, and exudation measurements were significantly different on day 2. The hyperbaric oxygen group showed a 42 percent reduction in wound hyperemia, a 35 percent reduction in the size of the lesion, and a 22 percent reduction in wound exudation (p values of 0.05, 0.03, and 0.04, respectively). No significant difference was noted for epithelialization. Observed differences in wound size, hyperemia, and exudation were attributable to hyperbaric oxygen therapy. This study further supports earlier conclusions that hyperbaric oxygen therapy is beneficial in a superficial dermal wound.

Blood Flow Velocity↗
PubMed1997

[Tissue oxygenation and microcirculation in dermatoliposclerosis with different degrees of erythema at the margins of venous ulcers. A contribution to hypodermitis symptoms].

BACKGROUND: In patients with chronic venous insufficiency erythematous areas in indurated skin (hypodermitis) and non erythematous areas of lipodermatosclerosis were examined. METHODS: In 13 patients with venous ulcers a total of 32 localizations in more or less erythematous and indurated ulcer edges were measured. The amount of erythema was taken as an indicator for the extent of hypodermitis. The parameters examined were erythema (a-value), skin temperature (t), laser Doppler flow (LDF), transcutaneous (tcpO2) and intracutaneous oxygen tension (icpO2). According to the amount of erythema the different localizations were separated into two groups: areas with a-values lower than 14,2 were classified as lipodermatosclerosis without or with little erythema, are-as with a-values higher than 14,2 were classified as areas of lipodermatosclerosis with extensive erythema. Identical measurements were also performed in healthy looking skin below the knee. RESULTS: Skin temperature and LDF were higher in areas with much erythema compared to those with little or no erythema. TcpO2, measured with an electrode temperature of 44 degrees C, was lower in areas with inflammation; tcpO2-values at 37 degrees C and icpO2-values showed no differences in ulcer edges with different amounts of inflammation. CONCLUSION: The results show differences of microcirculation between areas of lipodermatosclerosis with and without hypodermitis. These differences did not influence the actual tissue oxygenation in deeper parts in the dermis.

Aged↗
PubMedDate not supplied

Protection from radiation-induced alopecia with topical application of nitroxides: fractionated studies.

PURPOSE: Hair loss resulting from irradiation of the head and neck or from whole brain irradiation often leads to cosmetic, social, and psychological problems for the radiotherapy patient. Few successful clinical interventions are available. We have shown that nitroxides (stable free radicals) afford radiation protection against single-dose radiation-induced alopecia in a guinea pig model. Here we determine if topical nitroxide application provides protection from fractionated radiation treatment. MATERIALS AND METHODS: Two symmetrical and contralateral areas (3 x 5 cm) of skin on the dorsal trunk of guinea pigs were shaved to a hair length of 0.25 cm. A 2 mL solution containing 70 mg/mL nitroxide (Tempo or Tempol) in 70% ethanol was topically applied to the skin surface of one side; 70% ethanol was applied to the contralateral (control) side 10 minutes before irradiation. Animals were placed in a special jig that held skin without decreasing blood flow to the treatment area and fractionated external beam radiation (7 Gy) was delivered daily for eight fractions over 10 days via a 4 MeV linear accelerator. Alopecia (hair density) was scored weekly for 13 to 14 weeks after radiotherapy, using a standardized reference with respect to hair loss and regrowth in the treatment field. RESULTS: After radiation treatment, dry desquamation and gradual hair loss were observed for both control and nitroxide-treated skin; however, over weeks 4 to 11 postirradiation hair loss was much more pronounced in control animals when compared with nitroxide-treated animals. Hair density measurements for Tempol treatment over weeks 9 to 13 were approximately 75% compared with measurements in controls of approximately 25%. Tempo-treated animals exhibited hair density values of approximately 90% compared with 12% in controls over weeks 11 to 14. Tempol and Tempo treatments resulted in significant radioprotection. Histologic evaluation showed that radiation treatment alone in ethanol controls resulted in a marked decrease in the number of hair follicles and poor development of remaining follicles; however, nitroxide pretreatment resulted in no appreciable decrease in hair follicles and hair follicles appeared mature. This was also observed in unirradiated ethanol controls. Electron paramagnetic resonance studies revealed that topical nitroxide application did not result in measurable systemic concentrations of either drug. CONCLUSIONS: The results of this study suggest that topical application of nitroxides may be useful in a clinical setting to reduce the undesirable toxicity of radiation-induced alopecia.

Administration, Topical↗
PubMed1997

Implantable hearing device performance measured by laser Doppler interferometry.

Recent application of the Doppler principle laser interferometry to audiology, acoustics and otology has facilitated the development of implantable hearing devices (IHDs). During the design and testing of two different electromagnetic middle ear implants for sensorineural hearing loss, we used single-point laser Doppler interferometry (LDI). A commercially available interferometer, internally calibrated and validated against a National Institute for Standards and Technology (NIST) standard, was used with both mechanical fixtures and fresh temporal bones to evaluate implant mass, shape and orientation, attachment, electromagnetic coupling and acoustic properties. At both Hough Ear Institute and Symphonix Devices, Inc., we have shown that high fidelity and amplitudes can be recorded in vitro over a frequency range of 500 Hz to 10 kHz. These data can provide greater assurance of safety and efficacy to regulatory agencies before entering clinical trials. We propose that LDI be considered as an international standard for accurate, consistent comparison of performances of all IHDs during development. Furthermore, the future availability of human IHD data will allow for the extrapolation of a mechanical bench model of the middle ear transfer function for use in quality control during manufacturing and diagnosis of failure in IHDs.

Cochlear Implants↗
PubMed1997

Skin hyperemia in a habitual blusher.

Blushing, a vascular skin response to emotion is difficult to investigate since subjects are not able to blush on demand in a laboratory setting. Laser Doppler fluxmetry measures blood flux changes noninvasively. In a 28 year old lady distressed by habitual blushing we were able to document changes in skin blood flux during blushing. Forehead skin blood flux increased suddenly from 20 to 45 arbitrary units and returned to baseline values after about 3 minutes. It is the first time that emotionally provoked hyperemia in head skin is documented.

Blushing↗
PubMed1997

Acute ethanol effects on focal cerebral ischemia in nonfasted rats.

Focal cerebral ischemia was induced in a rat model of middle cerebral artery occlusion. Three groups of adult male Sprague-Dawley rats, given food and water ad libitum, were subjected to 4 hr of middle cerebral artery occlusion. All were given vehicle control and ethanol pretreatments intraperitoneally 1 hr before. Mean ipsilateral brain water content in the control, 2 g/kg ethanol, and 2 g/kg ethanol + insulin-treated groups showed: ischemia core: 81.1%, 82.5%, and 80.9%; intermediate zone: 81.0%, and 80.3%; and outer zone: 80.3%, 81.3%, and 80.1%, respectively. Brain Na+ and K4 content in these groups paralleled the water content. In addition to significantly (p < 0.05) more brain edema, the 2 g/kg ethanol-treated animal group also had significant hyperglycemia. In contrast, the 2 g/kg ethanol + insulin-treated animals were normoglycemic and had ischemic, intermediate, and outer zone Na+, K+, and Cl- levels comparable with the control group (p > 0.05). These results stress the importance of measuring and controlling plasma glucose levels in the in vivo studies of the neurotoxic effects of acute ethanol.

Alcoholic Intoxication↗
PubMedDate not supplied

[Hand ischemia due to "steal syndrome" in vascular access for hemodialysis].

Among complications of vascular access operations, symptomatic steal syndrome is uncommon, but may lead to ischemia of the hand. Between 1983 and 1995, 5 patients with hemodialysis fistulas presented rest pain of finger necrosis with a wrist-brachial index of 0.56 (range 0.35 to 0.63) improving to 0.96 (range 0.72 to 1.05) after digital pressure of the fistula. Ligation of distal radial artery was performed in 3 patients with side-to-end radiocephalic fistula, while basilic vein was distally ligated in a case of side-to-side brachiobasilic fistula. A vein "banding" procedure reduce fistula flow and improved distal perfusion in one patient, while a true venous aneurysm of the cephalic vein was treated by excision and replacement with a tapered PTFE graft. Hemodynamic assessment is required during surgical correction, but it may also be useful in pre- and intra-operative evaluation of patients undergoing therapeutical AVFs to prevent arterial insufficiency of the hand.

Adult↗
PubMed1997

Reproducibility of retinal and optic nerve head blood flow measurements with scanning laser Doppler flowmetry.

PURPOSE: To evaluate the interobserver variability and the reproducibility of retinal and optic nerve head capillary blood flow measurements performed with a new noninvasive equipment, the scanning laser Doppler flowmeter (Heidelberg Engineering, Heidelberg, Germany). METHODS: Blood flow measurements were performed during three independent sessions in six patients with glaucoma and five normal subjects using the scanning laser Doppler flowmeter (SLDF), which allows the visualization of perfused capillaries and vessels of the retina and optic nerve head and enables the quantification of capillary blood volume, flow, and velocity in any selected area of the perfusion map. To evaluate the interobserver variability in selecting the areas in the perfusion map to be measured, three observers tried to locate the same areas in the perfusion map of images obtained during the first session. To evaluate the reproducibility of the measurements, the observers measured correspondent areas in the peripapillary retina and in the optic nerve head of images from the three sessions. Areas of different sizes (10 x 10 pixels and 4 x 4 pixels) were measured. RESULTS: The agreement between readings performed by the three observers was very good, with the reliability coefficient for the various parameters varying from 0.90 to 0.98. The reproducibility of retinal and lamina cribrosa measurements with the 10 x 10 pixel square target was good (reliability coefficient for the different parameters ranging from 0.70 to 0.85) and much better than the reproducibility of the 4 x 4 pixel target. The measurements performed in the neuroretinal rim area also had poor reproducibility. The measurements from the patients with glaucoma tended to be more reproducible than those from normal subjects. CONCLUSIONS: The SLDF allows reproducible blood perfusion measurements of retinal and lamina cribrosa areas when a target square of 10 x 10 pixels is used.

Adult↗
PubMed1992

[Microcirculatory changes in mitral prolapse as an expression of a systemic change in the connective tissue].

Many authors hypothesize that mitral valve prolapse (MVP) can be, in most cases, only a clinical sign of a primitive and systemic disorder of the connective tissue, like in Marfan Syndrome (MS). In our previous works we supported the presence of morphological and functional alterations of the microcirculation in patients affected by MS. In order to characterize a possible common denominator between these pathologies we have studied the cutaneous microcirculation in a group of patients affected by MVP, divided into 2 groups: anatomic MVP (MVP) and MVP syndrome (MVPS). The morphologic parameters have been investigated by nailfold capillaroscopy while digital laser-Doppler was used to study skin flowmetry. The results have been compared with a control group. Capillaroscopic remarkers showed an architecturally disorganized microvasculature with aspects related to a reduced compactness of the microvasculature unit with a significatively higher score compared with controls (7.3 +/- 2.9 vs 3.6 +/- 1 p less than 0.0005). Laser-Doppler flowmetry showed a significatively reduced rest flow; ischemic test showed: spike time 48.9 +/- 36.9 vs 15.3 +/- 7.7 s (p less than 0.0005), hyperemic acme 6.6 +/- 2.7 vs 12.5 +/- 8.4 UP (p less than 0.002); % increase 32.1 +/- 20.2 vs 51.5 +/- 15.4 (p less than 0.002). Thermic test showed a significatively higher thermic acme 8.7 +/- 4.2 vs 12.6 +/- 9.11 UP (p less than 0.05). These results appeared to be correlated with stage pathology as it was observed a severe microvasculature disorders in MVPS. Therefore we suppose that a phenotypic continuum may exist between MS and MVP.

Adult↗
PubMed1994

Effects of neural blockade and general anesthesia on the laser-Doppler skin blood flow waves recorded from the finger or toe.

Effects of neural blockade and general anesthesia on the basic wave (BW) and the reflex wave (RW) among the laser-Doppler (L-D) skin blood flow waves recorded on the finger or toe were studied in 2 volunteers and 42 patients. The BW was continuous, rhythmic and independent of respiratory movements. The RW, which was induced by a deep inspiration or a snapping sound, was a transient marked reduction in blood flow. The BW was almost flattened and the RW was no longer induced at the finger under complete wrist block (n = 2), or under cervical or upper thoracic epidural anesthesia extended caudally over T7 (n = 2). On the other hand, the BW was still detected with reducing frequency and the RW could be provoked with one exception at the finger on the side with a sympathetic ganglion block at the C6 vertebral level (n = 14). The BW and RW at the toe were retained under lumbar subdural anesthesia (n = 6) as well. However, under the combination of lumbar subdural anesthesia and lower thoracic epidural anesthesia extending rostrally over T4 (n = 6), both the BW and the RW disappeared at the toe. In the course of deepening nitrous oxide/enflurane anesthesia (n = 10), the BW gradually reduced in frequency until it was almost flattened, and it became difficult to provoke the RW. L-D flowmetry of the finger or toe could be a useful clinical measure for detecting the presence or absence of sympathetic function controlling cutaneous vasomotion.

Adult↗
PubMed1982

Current status of noninvasive tests in the diagnosis of peripheral arterial disease.

In this review of the current status of the vascular laboratory, the major emphasis has been upon those tests that have become well-established and documented, including resting pressure, pulse volume measurements, velocity studies, and three stress measurements--exercise ankle pressure, postocclusive reactive hyperemia, and the toe pulse reappearance time. Additional technology that may have application to peripheral arterial disease includes photoplethysmography, transcutaneous oxygen tension, laser-Doppler velocimetry, fluorescein angiography, infrared thermography, and transcutaneous electromagnetic flowmetry. These techniques, which are currently in development and experimental trial, were not discussed but are likely to provide significant additional information. The future role of the vascular diagnostic laboratory in the area of peripheral arterial occlusive disease appears clear. It has already become a standard resource of the community hospital and tertiary referral center. Its functions will become more and more generally accepted with time as newly graduating physicians who have been exposed to this technology enter the practice of medicine. It should permit obtaining an evaluation of all patients at the expert level, aid in the education of all physicians concerned with peripheral arterial disease, and play an important part in guaranteeing a higher level of patient care than has heretofore been available.

Arterial Occlusive Diseases↗
PubMed1988

Partitional measurement of capillary and arteriovenous anastomotic blood flow in the human finger by laser-Doppler-flowmeter.

This study was made to see whether changes in blood flow through the capillaries and arteriovenous anastomoses (AVA's) of the human finger can be measured by noninvasive flowmetry. Total finger blood flow (FBF) was measured by venous occlusion plethysmography; blood flow was measured by a laser-Doppler flowmeter (ADVANCE, ALF-2100, Tokyo, Japan) using probes with optic fiber separations of 0.3 mm (LDF-0.3) and 0.7 mm (LDF-0.7). The maximum sensitivities for LDF-0.3 and LDF-0.7 were at depths of 0.8 and 1.2 mm from the tissue surface respectively. Two series of experiments were performed on separate days. In the first series the test hand was immersed in a water bath whose temperature (Tw) was 25 degrees C at an ambient temperature (Ta) of 25 degrees C. Tw was raised to 35 degrees C (local hand warming), which was then followed by an increase in Ta to 35 degrees C (whole body warming). FBF, LDF-0.3, and LDF-0.7 increased during these thermal stimulations. However, the relationship of FBF to LDF-0.3 showed two different regression lines. In contrast, the relationship of FBF to LDF-0.7 showed a single regression line. In the second series, with Ta at 35 degrees C, the test hand was immersed in a water bath at Tw 35 degrees C. Tw was then raised every 10 min by 2 degrees C steps from 35 to 41 degrees C. At Tw 39-41 degrees C, FBF and LDF-0.7 in the test hand were significantly decreased compared with those at Tw 35 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Selective vasodilators redistribute intestinal blood flow and depress oxygen uptake.

In this paper we report the effects of adenosine and isoproterenol on intestinal oxygen consumption. Using the recently developed technique of laser-Doppler velocimetry (LDV), we also studied the effects of these two agents on regional blood flow in the canine intestinal mucosa and muscularis. In isolated gut loops perfused at constant blood flow, both vasodilators depressed O2 uptake, but isoproterenol increased rubidium extraction while adenosine depressed rubidium extraction. Under constant pressure perfusion both dilators depressed O2 uptake but increased total flow. Isoproterenol increased the capillary filtration coefficient (Kf), but adenosine depressed Kf. LDV flowmetry showed adenosine increased muscularis flow and depressed mucosal flow. Both LDV flowmetry and radioactive microspheres showed isoproterenol increased mucosal but depressed muscularis flow. Our data indicate that the deleterious effects of isoproterenol and adenosine in depressing intestinal oxygen uptake can be explained by the ability of these agents to selectively vasodilate one of the regional circulations within the gut wall and by a "vascular steal" mechanism to reduce blood flow in the other vascular bed not as sensitive to the agent in question. The reduction in the regional blood flow thus depresses the O2 consumption of the gut as a whole. By comparing our regional laser-Doppler blood flow data with a simple analog model, we show that the seemingly paradoxical effect of vasodilators in depressing a regional blood flow while increasing total perfusion is explicable by a "vascular steal" mechanism.

Adenosine↗