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PubMedDate not supplied

Transpupillary thermotherapy for age-related macular degeneration: long-pulse photocoagulation, apoptosis, and heat shock proteins.

OBJECTIVE: To provide a biophysical foundation for using transpupillary thermotherapy (TTT) to manage choroidal neovascularization in age-related macular degeneration (ARMD). METHODS: Retinal temperature rise in laser therapy is proportional to retinal irradiance (laser power/area) for a particular spot size, exposure duration, and wavelength. TTT is a low irradiance, large spot size, prolonged exposure (long-pulse), infrared laser photocoagulation protocol. Results from an experimentally confirmed, finite element model of retinal light absorption and heat conduction are used to analyze laser parameter selection and its consequences. Results from apoptosis, heat shock protein and hyperthermia research are used to examine how chorioretinal damage from clinical procedures might be reduced. RESULTS: Chorioretinal thermal equilibration occurs during long-pulse TTT photocoagulation. Retinal temperature increases are similar in the RPE where laser radiation absorption is significant and in the adjacent neural retina where there is negligible radiation absorption. For parameters used to treat occult choroidal neovascularization in lightly-pigmented fundi (800-mW, 810-nm, 3-mm retinal spot diameter, 60-sec exposure duration), the maximum chorioretinal temperature elevation is calculated to be roughly 10 degrees C, significantly lower than the 20 degrees C temperature elevations measured in threshold, conventional short-pulse retinal photocoagulation. CONCLUSIONS: To achieve a preselected temperature rise, TTT laser power must be increased or decreased in proportion to the diameter rather than the area of the laser spot. Clinical power settings should be adjusted for fundus pigmentation and media clarity because both of these factors affect absorbed retinal irradiance and thus retinal temperature rise. Noninvasive thermal dosimetry currently is unavailable for clinical retinal photocoagulation, but potential thermometric techniques include MRI, liposomal-encapsulated dyes, multispectral imaging or reflectometry, and subretinal or episcleral thermometry. TTT may be useful not only as independent therapy, but also as an adjunct to PDT, antiangiogenic drugs and ionizing radiation therapy in the management of neovascular ARMD. Low temperature, long-pulse photocoagulation is a potential strategy for decreasing neural retinal damage in subsequent TTT or short-pulse photocoagulation and perhaps even for treating glaucoma or retinal degenerations.

Animals↗
PubMed2001

[Current techniques for the clinical evaluation of the microcirculation].

Three main types of approaches are currently used for the exploration of the microcirculation in man: Clinimetric measurements of the cutaneous temperature (thermometry), skin color (chromametry) and tissue volume (leg or foot volumetry) allow a quantification of clinical indexes of skin blood flow, blood volume and edema that are useful in therapeutic trials. Global parameters evaluating the hemodynamic or nutritional efficacy of the microcirculation in a tissue sample (laser Doppler and TcPO(2)) are easy to perform in clinical routine. TcPO(2) measurements through Clarke electrodes or fluorescence lifetime imaging technology evaluate the nutritional efficacy of the microcirculation. Laser Doppler devices are producing a semi-quantitative index of superficial tissue perfusion, that can be split into a volumic and a velocimetric components; its high sensitivity makes it a valuable tool for clinical research, mainly for dynamic measurements of reactivity of the superficial microcirculation to various stimuli. New instruments are able to use two different frequencies in order to compare tissue perfusion at different depths beneath the skin surface. The combination of a laser probe and a small automate can produce a two-dimensional image allowing the evaluation of spatial heterogeneity in tissue perfusion. Visualization of the skin capillary bed, i.e. capillaroscopy, was recently improved by the emergence of flexible videomicroscopes easily allowing the exploration of the whole body skin surface and not only the classical site of the nailfold. The use of the method was therefore broadened from vascular acrosyndromes and connective tissue diseases to the whole spectrum of skin trophic changes of the extremities. Combination with digital image analysis systems allows the quantification of the microvascular and microlymphatic structure (quantitative appraisal of microangiopathies) and function (capillary hemodynamics and exchange). Laser-doppler and capillaroscopy can also be combined for the measurement of red blood cell velocity in single capillaries.

Capillaries↗
PubMed2001

Application criteria for infrared ear thermometers in pediatric surgery.

Fever is an important and sensitive indicator of infectious diseases in children. For the past decades, measurement of body temperature in routine medical practice was limited to oral, rectal and axillary sites. In infants and children, however, temperature measurements are further limited to the rectal and axillary sites due to technical and clinical considerations. In the field of pediatric surgery, pathological and surgical conditions of the ano-rectal area often further restrict the application of conventional rectal temperature measurements. The application of tympanic temperature measurements in such pediatric surgical pathologies provides a reliable alternative to conventional rectal temperature measurements. The pediatric surgical clinico-pathological states where ear temperature measurements are the only mode of accurate temperature determination have been identified. Tympanic thermometry is well tolerated by children and predicts temperature with relative accuracy within a few seconds.

Body Temperature↗
PubMedDate not supplied

Evaluation of clinical thermometers for accuracy and reliability.

The purpose of this study was to examine the accuracy and reliability of a wide range of clinical thermometry instruments and technologies. In a historical sense, the purpose of this study was to determine if the improvements in speed, ease of use, and safety realized in the last 100 years have been offset by a loss of accuracy and/or reliability. In view of current events, the purpose was to determine if the new generation of electronic, digital clinical thermometers could be used to replace the traditional glass/mercury thermometers. Nine clinical thermometers representing electronic, digital oral, and predictive oral; electronic, digital infrared tympanic; and liquid crystal urinary technologies were evaluated. Accuracy was determined by comparing the temperatures obtained from these test instruments with those of the reference, glass/mercury oral thermometer. Reliability was determined by test-retest evaluation. All of the thermometers evaluated were significantly less accurate when compared with the reference thermometer in this study. All of the test instruments significantly underestimated higher temperatures and overestimated lower temperatures. This study indicated that the improvements in safety, speed, and ease of use of the newer clinical thermometers have been offset by a loss in accuracy and reliability. It also indicated that the current generation of electronic, digital clinical thermometers, in general, may not be sufficiently accurate or reliable to replace the traditional glass/mercury thermometers.

Adult↗
PubMed2001

[Hamartoma oligemicus].

BACKGROUND: Naevus oligemicus is a rare affection caused by selective vasoconstriction of the deeper vessels ("thermal" skin blood flow), with respect of the superficial vascular plexus ("nutrient" blood flow). We report the fourth case. CASE REPORT: A 45 year-old man presented erythematocyanotic lesions with sensation of coolness on the abdomen and the thighs. These lesions had first been noted by the patient 3 years earlier. Physical examination and laboratory investigations were normal. Histology of a lesion revealed a non-specific superficial dermatitis. Result of skin surface thermometry of both areas showed that the surface temperature of the involved skin was up to 2 degrees C lower than the surrounding control skin. DISCUSSION: We don't know why there is a selective vasoconstriction of the deeper vessels and not of the superficial vascular plexus. Naevus oligemicus belongs to the pharmacological naevus group because of the absence of any histologic vascular abnormality. The functional abnormality has not been identified. This could be explained either by increased sympathetic vasoconstrictor tone in the autonomic sympathetic vasoconstrictor nerves supplying the deeper thermoregulatory vasculature in the affected skin, or by increased sensitivity of these vessels to vasoconstrictor catecholamines.

Diagnosis, Differential↗
PubMed1975

Temperature of mixed venous blood during exercise.

The temperature of mixed venous blood (PA-temp) was measured in the pulmonary artery of healthy male volunteers at rest and during bicycle exercise in the supine position. Oxygen uptake, arteriovenous oxygen difference, and heart rate were determined simultaneously. The subjects were studied both in their basal normokinetic circulatory state and in a hypokinetic circulatory state induced by beta-receptor blockade with propranolol. The PA-temp increased linearly with rising oxygen uptake. During beta-receptor blockade the exercise-induced rise in PA-temp was considerably steeper in relation to work load and to oxygen uptake. Thus when the ordinary ability to increase cardiac output was suppressed by propranolol, an identical dynamic exercise induced a significantly higher PA-temp. A significant correlation (r = 0.92) was found between the rise in PA-temp during exercise and the increase in the arteriovenous oxygen difference. This correlation, which has not been described previously, was not altered by beta-receptor blockade. It is concluded that the close correlation between blood temperature and arteriovenous oxygen difference has a clinical potential for hemodynamic measurements. A simple method for the indirect estimation of arteriovenous oxygen difference by means of blood thermometry would be a considerable laboratory advantage.

Adult↗
PubMed2002

Radiofrequency energy-induced heating of bovine articular cartilage: evaluation of a new temperature-controlled, bipolar radiofrequency system used at different settings.

This in vitro investigation determined temperature changes associated with radiofrequency energy-induced heating of bovine articular cartilage using a newly developed, temperature-controlled, bipolar radiofrequency system at different settings. Cartilage tissue samples were placed in a saline bath maintained at room temperature. Radiofrequency energy was applied using a temperature-controlled, bipolar radiofrequency system at four different settings. Fluoroptic thermometry recorded temperatures at the radiofrequency electrode-tissue interface at 1-second intervals before, during delivery (1-5 seconds), and after delivery (1-3 seconds) of radiofrequency energy. Ten data acquisitions were obtained at each equipment setting. There were statistically significant (P<.05) increases in cartilage tissue temperatures associated with the different temperature settings. The temperature at the radiofrequency electrode-tissue interface was relatively close to the equipment's set temperature. These data provide basic information for the temperature-controlled, bipolar radiofrequency system applied to articular cartilage and may be useful in guiding electrosurgical equipment for thermal-assisted chondroplasty.

Analysis of Variance↗
PubMed1975

Clinical and hormonal aspects in breast cancer with special reference to malignant evolutive push.

It is tried to differentiate between various stages of malignant evolutive push and normal mammary tumors to establish an individual therapeutic procedure. Besides mammography and thermometry, investigations of urinary excretions of estrogenic and androgenic steriods are qualified for this purpose. Patients with malignant evolutive push showed an increased excretion of estrogens which reached its highest levels in patients suffering from inflammatory mammary carcinomas. The excretion of 17-ketosteroids shows a behaviour vice versa. Altogether mammary tumors with malignant evolutive push are characterized by a state of absolute and relative hyperestrogenity respectively. This phenomenon preferably depends on the clinical stage of the disease than on the age of the patients.

17-Ketosteroids↗
PubMed1975

[Thermogenesis of breast cancers. V. The effects of 60Co radiotherapy and the correlations with expectations of a cure].

The action of ionizing radiation on the metabolic heat production by cancers has been investigated on a group of 24 small breast carcinomas (T1 and T2), all treated exclusively by radiotherapy under equivalent conditions (60Co) and then followed up regularly (mean recall period of five years). Following techniques have been used: intratumoral thermometry and fluvography for computing the specific heat power of the tumour, infrared thermography for analysing the skin thermal pattern quantitatively. Comparison between clinical, radiographical and thermal findings has more especially shown; a) the constant agreement between the final loco-regional results of radiotherapy and the evolution of both the heat production by the tumour and the related hyperthermia on the skin; b) the early appearance of the thermal signs of either a regression or a recurrence of the tumour, compared with the corresponding morphological signs. The fundamental and practical consequences can be summarized as follows: 1 degree distinction between radiosensitive and radioresistant carcinomas accroding as the specific heat power of the tumour is reduced or not after irradiation; 2 degrees definition of three types of thermal evolution by normalization, regression followed by re-increase, and continuance of both tumour heat production and malignant skin hyperthemia, and corresponding to the clinical concepts of sterilization, recurrence and nonsterilization respectively; 3 degrees justification of the systematic use of thermal methods for post-irradiation follow-up, especially to detect a local recurrence earlier and to specify the nature of a doubtful remaining opacity; 4 degrees description of objective thermal criteria allowing to decide a repairing mastectomy within shorter delays.

Adult↗
PubMed1975

[Thermal sensation and the thermoregulatory vascular reactions in man].

It was shown by the method of continuous highly sensitive thermometry of the human skin with a simultaneous recording of the verbal reports of the thermal feeling that the most important thermoregulatory reactions of the dermal vessels of the limbs were definitely related to the particular temperature sense.

Blood Vessels↗
PubMed1975

[Hemodynamic disorders in nonspecific chronic leg ulcers].

The state of regional hemodynamics in crural ulcers was studied in 180 patients by means of hemodynamic tests, oscillography, capillaroscopy, thermometry, phlebotonometry, phlebography. studies of blood biochemistry and gas content, as well as acidbase reserves. The changes observed proved to be not identical in varicous, thrombotic, ischemic, traumatic and pyogenic ulcers. The pathogenetic importance of and conditions for a secondary development of some or other hemodynamic disorders were determined, which being kept in mind permit an individual approach to the therapy, including the methods of correction of arterial and venous blood flow.

Adult↗
PubMedDate not supplied

MR imaging-related heating of deep brain stimulation electrodes: in vitro study.

BACKGROUND AND PURPOSE: Recent work has shown a potential for excessive heating of deep brain stimulation electrodes during MR imaging. This in vitro study investigates the relationship between electrode heating and the specific absorption rate (SAR) of several MR images. METHODS: In vitro testing was performed by using a 1.5-T MR imaging system and a head transmit-receive coil, with bilateral deep brain stimulation systems positioned in a gel saline-filled phantom, and temperature monitoring with a fluoroptic thermometry system. Standardized fast spin-echo sequences were performed over a range of high, medium, and low SAR values. Several additional, clinically important MR imaging techniques, including 3D magnetization prepared rapid acquisition gradient-echo imaging, echo-planar imaging, quantitative magnetization transfer imaging, and magnetization transfer-suppressed MR angiography, were also tested by using typical parameters. RESULTS: A significant, highly linear relationship between SAR and electrode heating was found, with the temperature elevation being approximately 0.9 times the local SAR value. Minor temperature elevations, <1 degrees C, were found with the fast spin-echo, magnetization prepared rapid acquisition gradient-echo, and echo-planar clinical imaging sequences. The high dB/dt echo-planar imaging sequence had no significant heating independent of SAR considerations. Sequences with magnetization transfer pulses produced temperature elevations in the 1.0 to 2.0 degrees C range, which was less than theoretically predicted for the relatively high SAR values. CONCLUSION: A potential exists for excessive MR imaging-related heating in patients with deep brain stimulation electrodes; however, the temperature increases are linearly related to SAR values. Clinical imaging sequences that are associated with tolerable temperature elevations in the <or=2.0 degrees C range at the electrode tips can be performed safely within an SAR range <2.4 W/kg local (0.9 W/kg whole body averaged).

Body Temperature↗
PubMed2002

[Characteristics of the human thermal state and environment in long-term space flight].

Summarized are data of many-year studies of thermal loading and thermal state of humans in different microclimates. Comparative analysis of various approaches to thermal monitoring of cosmonauts in space suits was performed with the conclusion about advantages of parotid thermometry. To set microclimate standards for long-term space flight, a complex index of the environment cooling potential (ECP) based on the use of an electrical dynamic catathermometer has been proposed. A correlation between ECP values and cosmonaut's thermal sensations was elicited. For the most part, the proposed recommendations have been verified or introduced in the space crew medical care system.

Astronauts↗
PubMed1976

[Heat content of the body as a basic parameter of thermoregulation].

With the aid of thermometry and calorimetry, the role of the organism's heat degree for the vasomotor response of the ear skin was studied in the rabbit. The calorimetric temperature was constant (19-21 degrees C) throughout the experiment. The heat threshold varied from 86 cal/kg to 320 cal/kg, depending on the different initial heat degrees in the animal. The increase in the organism's heat degree is concluded to be the main mechanism for initiation of the heat loss responses.

Animals↗
PubMed1992

[The temperature changes in different organs during immersion hypothermia].

Precise thermometry of the brain, liver, rectum, muscles and skin surface was performed in white rats in conditions of immersion of the body in water with the temperature 1 degree C. Breathing arrested within 15-18 min after immersion, their brain temperature being 16.7-18.2 degrees C, liver temperature 12.7-15.2 degrees C, rectum--10.4-15.5 degrees C, muscle 8.3-12.0 degrees C, skin surface--1.6-5.0 degrees C.

Animals↗
PubMed1992

[Body thermal status under low-temperature conditions in brewing production].

The purpose of the present study is to trace the thermal state of workers exposed to low temperatures in brewery production, establishing the heat loss and the stress of thermoregulation. The investigations are performed in the departments for fermentation, deposit, cask washing and filling of 3 brewery plants. In order to characterize the microclimate methods of thermometry, psychometry and catathermometry are used. The heat state is controlled by methods of subjective heat perception, skin temperature, average skin temperature, temperature gradients, oral, rectal and average body temperature and the thermal content. The results of the physiological examinations point out to significant loss, which affects not only the periphery but also the deep tissues. There is an expressed risk of supercooling of the organism. The data of the heat deficit impose a correction of the working clothes and limitation of the exposure.

Adult↗
PubMed2003

[Linezolid for the treatment of nosocomial infections after cardiac surgery].

Clinical and bacteriological efficacy of linezolid in the treatment of cardiosurgical patients with various localization nosocomial infections due to problem grampositive cocci was estimated. The group included 10 patients: children at the age 3 months to 12 years (n = 3) and adults at the age of 17 to 65 years (n = 7) with infectious complications such as infectious endocarditis (n = 4), pneumonia (n = 2), wound infection (n = 3) and sepsis (n = 1). All the patients isolated MR staphylococci. The use of glycopeptides was not possible in 6 patients because of vancomycin intolerance (n = 1), renal insufficiency (n = 1) and failure of the previous vancomycin therapy (n = 4). To all the patients linezolid was administered per os (tablets or suspension) or intravenously (infusion solution) in doses of 600 mg twice a day (1200 mg a day) for the adults and 10 mg/kg body weight every 12 hours (20 mg/kg body weight a day) for the children. Linezolid monotherapy was applied to 2 patients. 8 patients were treated with linezolid in combination with some other antibiotics. By the clinical findings the positive dynamics confirmed by thermometry and hemograms was observed in 8 patients beginning from the 4th day of the linezolid use. Eradication of MR staphylococci from the blood, sputum and wounds was stated in all 10 patients. No toxic or adverse reactions were noted. It was concluded that linezolid is an optimal alternative to vancomycin especially when the use of the latter is not possible. No nephrotoxic effects of linezolid provided its recommendation as a drug of choice in the treatment of patients with renal disturbances, including polyorganic insufficiency.

Acetamides↗
PubMed2004

[A study of the condition of parodentium in patients with stomach and duodenal ulcer].

The objective of this research was a study of the condition of parodentium tissues in patients with ulcer. 51 ulcer patients were studied. As a result of complex studies (hemorrhage coefficient, crevicular liquid, papilloalveolar marginal index, complex periodontal index and thermometry), apparent inflammatory processes were discovered in parodentium tissues. Inflammatory parodentium changes do not disappear completely with the complex anti-ulcer therapy that forms a basis for the simultaneous application of local therapeutic measures to eliminate inflammatory processes in parodentium tissues.

Adult↗