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At least 973 records · Page 54Linked to original sources
PubMed1995

Lack of association between atelectasis and fever.

Postoperative fever occurs in many patients. If no infection is found, atelectasis, if present, may be blamed. This study of 100 postoperative cardiac surgery patients followed up from day of surgery through the second postoperative day with daily portable chest radiographs and continuous bladder thermometry was designed to look for an association between atelectasis and fever. The daily incidence of atelectasis increased from 43 to 69 to 79%. However, the incidence of fever, defined as temperature > or = 38.0 degrees C fell from 37 to 21 to 17%. When defined as temperature > or = 38.5 degrees C, the daily incidence of fever fell daily from 14 to 3 to 1%. Using chi 2 analysis, no association could be found between fever and amount of atelectasis. This contradicts common textbook dogma but agrees with previous human study and animal experiments.

Adult↗
PubMed1991

[Development and evaluation of a multi-applicator system of endocavitary radiothermotherapy of gynecologic tumors].

An applicator system for the radiothermotherapy of gynecological tumors has been developed. The concept is based on combining high-dose rate afterloading therapy with local hyperthermia (27.12 MHz). The main applicator, the rf-gamma applicator consists of a guide tube for the gamma source, an electrode system and a cooling system. Isodoses and isotherms can be adapted to the individual anatomical-pathological situation presenting. For therapy planning the interaction between the applicators and the perfused tissue was investigated in a theoretical FEM model. In the first step, the SAR-function in the vicinity of the rf-applicator was determined by means of a 2D FEM calculation. In a second step, the 3D temperature fields was determined using linear shape functions. The results of these calculations showed that in every case the hot spots shifted from the applicator surface into the depths of the tissue. With the aid of an infrared camera and a split phantom the calculations were examined in a homogeneous non-perfused tissue model. Thermometry confirmed the accuracy of the results obtained. The radiothermotherapy system described here was tested in animal experiments, and is presently being used in a clinical pilot study.

Animals↗
PubMed1978

Trends and aspects in clinical chemistry.

This paper first seeks to evaluate current trends in methodology and technology and discusses possible implications for the future of clinical chemistry, whose range and diversity of tasks are carefully defined. It is thought that the remarkable development in the field of immunological methods, in the general sense of the work, will continue for the years to come. One other principle, which it is predicted will play an increasing role, is thermometry for the determination of enthalpy. Similarly, new developments in the fields of bio- and chemoluminescence offer interesting possibilities. The impact of the computer in clinical chemistry is also discused. Secondly, the double role of clinical chemistry as a diagnostic speciality and as an academic field is analyzed. On the one hand, the need for closer cooperation both with other diagnostic subspecialities and with other medical clinical disciplines is stressed. In particular, newly organized Departments of Laboratory Medicine encompassing microbiology, cytology, nuclear medicine, toxicology etc. might contribute greatly to interdisciplinary understanding. On the other hand, problems of clinical medicine and of certain areas within biological research should be at the center of interest of the future research-oriented clinical chemist.

Allergy and Immunology↗
PubMed2004

A new method for the experimental assessment of finger haemodynamic effects induced by a hydraulic breaker in operative conditions.

The haemodynamic effects, in terms of grip force and hand-transmitted accelerations, produced on the fingers of 10 healthy subjects by operation of a hydraulic breaker held with a low or a high grip were investigated with a new experimental set-up. A novel apparatus consisting of a capacitive sensor matrix and a laser Doppler vibrometer was used to measure the two parameters during breaker operation. Finger blood flow in basal conditions and after each test was evaluated in the four long fingers of both hands with a photoplethysmograph and superficial skin thermometry. The amplitude of the accelerations transmitted to the hand surface was greater during the test with the low grip. Photoplethysmographic and thermometric values were significantly lower than basal values after either test. The amplitude of photoplethysmographic values during the tests was significantly lower with the low than with the high grip in 6 subjects, in both index fingers, and in the right middle finger. The authors show that the level of grip force used for holding the breaker causes transmission of vibrations of wider amplitude, resulting in greater reduction in finger blood flow. In line with the literature, stimulus magnitude, frequency and duration affected finger blood flow, especially in the index finger.

Adult↗
PubMed1990

[Deep temperature of the temporomandibular joint region at rest].

This study was made to measure non-invasively the deep temperature of the temporomandibular joint [TMJ] region at rest. The transcutaneous probe making use of zero-heat-flow method was utilized for the deep thermometry. The following results were obtained. 1. In 20 normal male subjects, no differences of the deep temperature were recognized between the right and the left TMJ regions. 2. In 10 patients with temporomandibular disorders, the deep temperature of the symptomatic TMJ side was significantly higher than that of asymptomatic side.

Body Temperature↗
PubMed2004

MRI guidance of focused ultrasound therapy of uterine fibroids: early results.

OBJECTIVE: The purpose of this study was to explore our hypothesis that MRI-guided focused ultrasound therapy for the treatment of uterine fibroids will lead to a significant reduction in symptoms and improvement in quality of life. We describe focused ultrasound therapy applications and the method for monitoring the thermal energy deposited in the fibroids, including the MRI parameters required, in a prospective review of 108 treatments. MATERIALS AND METHODS: Patients presenting with symptomatic uterine fibroids who attained a minimal symptom severity score and who would otherwise have been offered a hysterectomy were recruited. Thermal lesions were created within target fibroids using an MRI-guided focused ultrasound therapy system. The developing lesion was monitored using real-time MR thermometry, which was used to assess treatment outcome in real time to change treatment parameters and achieve the desired outcome. Fibroid volume, fibroid symptoms, and quality-of-life scores were measured before treatment and 6 months after treatment. Adverse events were actively monitored and recorded. RESULTS: In this study, 79.3% of women who had been treated reported a significant improvement in their uterine fibroid symptoms on follow-up health-related quality-of-life questionnaires, which supports our hypothesis. The mean reduction in fibroid volume at 6 months was 13.5%, but nonenhancing volume (mean, 51 cm(3)) remained within the treated fibroid at 6 months. CONCLUSION: This early description of MRI-guided focused ultrasound therapy treatment of fibroids includes follow-up data and shows that, although the volume reduction is moderate, it correlates with treatment volume and the symptomatic response to this treatment is encouraging.

Adult↗
PubMedDate not supplied

Screening for fever by remote-sensing infrared thermographic camera.

BACKGROUND: Following the severe acute respiratory syndrome (SARS) outbreak, remote-sensing infrared thermography (IRT) has been advocated as a possible means of screening for fever in travelers at airports and border crossings, but its applicability has not been established. We therefore set out to evaluate (1) the feasibility of IRT imaging to identify subjects with fever, and (2) the optimal instrumental configuration and validity for such testing. METHODS: Over a 20-day inclusive period, 176 subjects (49 hospital inpatients without SARS or suspected SARS, 99 health clinic attendees and 28 healthy volunteers) were recruited. Remotely sensed IRT readings were obtained from various parts of the front and side of the face (at distances of 1.5 and 0.5 m), and compared to concurrently determined body temperature measurements using conventional means (aural tympanic IRT and oral mercury thermometry). The resulting data were submitted to linear regression/correlation and sensitivity analyses. All recruits gave prior informed consent and our Faculty Institutional Review Board approved the protocol. RESULTS: Optimal correlations were found between conventionally measured body temperatures and IRT readings from (1) the front of the face at 1.5m with the mouth open (r=0.80), (2) the ear at 0.5 m (r=0.79), and (3) the side of the face at 1.5m (r=0.76). Average IRT readings from the forehead and elsewhere were 1 degrees C to 2 degrees C lower and correlated less well. Ear IRT readings at 0.5 m yielded the narrowest confidence intervals and could be used to predict conventional body temperature readings of < or = 38 degrees C with a sensitivity and specificity of 83% and 88% respectively. CONCLUSIONS: IRT readings from the side of the face, especially from the ear at 0.5 m, yielded the most reliable, precise and consistent estimates of conventionally determined body temperatures. Our results have important implications for walk-through IRT scanning/screening systems at airports and border crossings, particularly as the point prevalence of fever in such subjects would be very low.

Adolescent↗
PubMedDate not supplied

Phase I evaluation of hyperthermia equipment--University of Utah institutional report.

At the University of Utah Medical Center the thrusts of the effort with respect to the NCl Hyperthermia Equipment Evaluation Contract have been threefold. The first objective was the development of a reliable thermometry system for collecting temperature information as a function of space as well as time. The second objective was the evaluation and comparison of a number of hyperthermia devices, particularly with respect to deep-heating devices, and specifically as pertains to the BSD annular phased array system (AA) and its various configurations. The third objective was to develop methodology for analysing hyperthermia data which could be easily adapted toward device comparison. In the period from 10/81-1/86, a total of 137 patients were treated with one or more of 10 devices, totalling 199 device evaluations at the University of Utah Medical Center or the subcontracting institution, LDS Hospital. Of these, 132 device evaluations involved deep-seated tumours. The AA was found to be feasible for deep pelvic regional hyperthermia, although the frequency of reversible acute toxicity was high, and achievement of desired temperatures was frequently limited by one of several factors. The radiative electromagnetic wave applicators which were evaluated for treatment of superficial tumours were found to be mostly feasible for tumours of the thoracic and extremities regions, although the heating patterns were frequently too shallow or too small in area, when compared with the size of the lesion.

Equipment Design↗
PubMedDate not supplied

A phase I/II study of combined cisplatin and hyperthermia treatment for refractory malignancy.

Research in animal and human cell cultures has shown that some chemotherapeutic agents, cisplatin in particular, have cytotoxicity that is significantly potentiated at elevated temperatures. Concurrent administration of systemic cisplatin and local hyperthermia in human patients has not been previously reported. A phase I/II study was undertaken to assess the systemic and local toxicities and activity of concurrently administered local hyperthermia and systemic cisplatin in human tumours. Nine patients with histologically proven malignant tumours have been treated from March 1985 to July 1987. Their histologies were: breast, four; SCC of head and neck, two; SCC of skin, one; malignant melanoma, one; synovial cell sarcoma, one. Once-weekly hyperthermia was administered for 60 min by external microwave devices in an attempt to achieve minimum intratumoral temperatures of 42 degrees C. Plastic catheters were placed intratumorally under CT guidance for thermometry purposes. Cisplatin 40-60 mg/m2 was given over 60 min when steady-state heating was achieved. A total of 44 treatments are available for analysis. All nine patients had minimum intratumoral temperatures below the desired goal of 42 degrees C, and only two patients achieved average intratumoral temperatures of 42 degrees C or greater. Two of the responding patients sustained significant thermal injury consisting of blistering and necrosis. Three patients required transfusion and delay of weekly treatment because of anaemia and leukopenia. Four patients had partial response (PR) and one patient had minor response (MR) within the heated treatment volume. Three of these five patients experienced significant subjective palliation. This combination of treatment modalities can be delivered safely.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Heat loss and blood flow during hyperthermia in normal canine brain. I: Empirical study and analysis.

The effects of blood flow and thermal conduction during microwave hyperthermia were investigated in normal canine brain. Heating was accomplished with an external microstrip spiral antenna and temperature measurements were made using a multichannel fluoroptic thermometry system. In order to determine cooling rates, temperature measurements made during cooling were fitted with a model consisting of a constant value and an exponential term. Data from experiments in both perfused and non-perfused brains could be fitted with this simple model. The resulting cooling rates indicated that heat loss by conduction is comparable to that by blood flow. In another series of experiments, temperature measurements were made during several 1 min cooling intervals in which the power was shut off intermittently during a 35 min heating episode. Results were consistent with a 2-3-fold increase in blood flow rate which occurred gradually throughout the course of heating. Parameters that affect the determination of cooling rates are discussed in terms of the bioheat transfer equation. These investigations demonstrate that a simple heat sink model provides a good representation of the cooling data for the thermal distributions obtained.

Animals↗
PubMedDate not supplied

Microwave applicator for transurethral hyperthermia of benign prostatic hyperplasia.

An applicator for heating the prostate gland using a transurethral approach is described. This technique uses three microwave antennas and a thermometry sensor attached to the outer surface of a balloon (Foley) type urological catheter. Each microwave antenna also includes a built-in thermistor to control temperature and balance power. The balloon catheter assures rapid and reproducible localization of the antennas in the prostatic urethra. The two-dimensional SAR and steady-state temperature distributions surrounding the applicator in tissue equivalent phantom are reported. Longitudinal temperature distributions measured in situ at the applicator-urethral interface and the longitudinal and radial temperature distributions measured in normal canine prostate are presented and discussed. The technique appears to be capable of elevating temperature to greater than 42 degrees C in a cylindrically symmetrical volume up to 5 cm length and 0.5 cm radial penetration surrounding the applicator.

Hot Temperature↗
PubMedDate not supplied

Comparative thermal dosimetry of interstitial microwave and radiofrequency-LCF hyperthermia.

Steady-state temperature distributions induced by commercial radiofrequency localized current field (RF-LCF) and microwave (MW) interstitial heating systems were compared in dog thigh muscle in vivo using repeated 15-min heating experiments in the same implant site. Control experiments consisting of up to nine successive, identical heat trials with either modality verified that induced temperature distributions could be duplicated reliably. For all comparative dosimetry experiments a square array of parallel heat sources and thermometry probes was inserted percutaneously through a 5 mm grid Plexiglas template to a depth of 7.0-8.0 cm. Metal trocar electrodes were left at the corners of square arrays for two or three successive RF-LCF heat trials. After the metal trocars were removed, two or three more heat trials were performed using dipole microwave antennas in Teflon catheters at the same four positions. The three-dimensional temperature distributions within the array boundaries were characterized by mapping up to 11 fibre optic temperature probes in 1 cm increments during the steady-state plateau of each trial. The distributions were analysed quantitatively in terms of the percentage of measured points which achieved at least 50 per cent of the maximum array temperature increase above baseline (delta Tmax). Results showed that the RF-LCF technique heated more uniformly with depth along the bare metal electrodes and more consistently within the array boundaries than the microwave dipole antennas. For all array spacings studied (1.0-3.5 cm), the RF electrodes heated approximately 10-20 per cent more of the array volume to greater than 50 per cent of delta Tmax.

Animals↗
PubMedDate not supplied

Multi-institutional clinical studies on hyperthermia combined with radiotherapy or chemotherapy in advanced cancer of deep-seated organs.

Multi-institutional studies on clinical hyperthermia of deep-seated tumours were undertaken using 8 MHz radiofrequency capacitive heating devices (Thermotron RF-8) at seven institutions. Each institute was designated to treat specific organs. This paper contains the accumulations of the results obtained at different institutions charged for different tumours. Deep-seated tumours in the lung, stomach, pancreas, liver, urinary bladder and rectum were treated. A total of 177 cases examined from January 1985 to December 1988 included 96 cases (54%) treated with radiotherapy plus hyperthermia, among which 14 cases were pre-operative. Of 177 cases, 81 (46%) were treated with chemotherapy plus hyperthermia. Complete response (CR) and partial response (PR) were obtained in 80% of the cases with lung cancer, 39% with stomach cancer, 56% with liver cancer, 35% with pancreas cancer, 71% with urinary bladder cancer, 100% with primary rectal cancer, and 47% with recurrent rectal cancer. Thermometry was performed using two techniques; one is direct measurement of intratumour temperature in lung and liver cancers, the other is indirect measurement of intracavitary temperature for stomach, pancreas, urinary bladder and rectal cancers. Intratumour temperatures were measured in 30 of the 43 tumours of the lung and liver. The maximum tumour temperature was greater than 42 degrees C in 23 (77%) of the 30 tumours. Intracavitary temperatures were measured in 133 (99%) of the 134 tumours of stomach, pancreas, urinary bladder and rectum. An intracavitary temperature greater than 42 degrees C was obtained in 98 (73.7%) of the 133 tumours. The contribution of hyperthermia in improving the quality of life of patients under terminal care was also investigated. It was indicated that hyperthermia was one of the most effective treatment techniques for advanced or inoperable cases. In this study local control rate (LCR) was mainly discussed because the period of follow-up was only 3 years. Side-effects were observed in 37 cases (21%); main side-effects were fatty induration, pain during treatment and burn. However, no side-effects were severe enough to interrupt therapy.

Adult↗
PubMedDate not supplied

Positioning of temperature measurement points using multiplanar computed tomography.

A method is described for the use of computed tomography and multiplanar reconstruction to depict in single images the full course of obliquely running thermometry catheters. In 14 patients given thermoradiotherapy for locally advanced breast carcinoma, reformatted images of the full catheter course were obtained for all 98 catheters so far tested. The main clinical advantage of this time-consuming procedure was the ability to determine the localization within the catheters of individual temperature measurement points of multipoint thermistor probes. It was also possible to study the localization of the measurement points in relation to the tumour margins.

Breast Neoplasms↗
PubMedDate not supplied

Catheter induced temperature artifacts in ultrasound hyperthermia.

Temperature artifacts were evaluated at 72 different sensor locations in 10 different tumour sites heated by use of planar ultrasound transducers operated at 1 and 3 MHz. Thermometry was carried out by single- and multisensor thermocouple probes inserted into 19- and 16-gauge polyurethane catheters, respectively. Nearly all catheters were oriented approximately perpendicular to the ultrasound beam. The artifacts were determined by backward extrapolation of the thermal decay 30-60s after the power was turned off. The effective blood flow and specific absorption rate (SAR) at the sensor locations were determined from the rate of decay and the steady-state temperature. The sample mean steady-state temperature, effective blood flow, and SAR were 41.4 degrees C, 17.5 ml/100 g/min, and 46.3 W/kg, respectively. The most frequent artifact was in the range 0-0.2 degrees C and the mean artifact was 0.6 degrees C. Less than 15% of the artifacts were above 1 degree C. The magnitude of the artifact correlates with the SAR of ultrasonic power, the effective blood flow rate, and the steady-state temperature. These results indicate that the artifact produced at 1 MHz by a multisensor, Teflon-sheathed thermocouple inserted into a 16-gauge polyurethane catheter is 1.7 +/- 0.4 degrees at an SAR of 100 W/kg.

Body Temperature↗
PubMedDate not supplied

The local tissue cooling coefficient: a unified approach to thermal washout and steady-state 'perfusion' calculations.

Several investigators have attempted to utilize either transient 'thermal washout' and/or steady-state temperature data from standard hyperthermia thermometry to obtain information regarding both tumour and normal tissue perfusions, and transient data to measure SAR distributions. This paper reviews that literature, presents a unified theoretical basis for all of the temporal 'perfusion' approaches, and shows that both the steady-state and the 'washout' techniques actually measure the same quantity, which is related to, but not equal to, the tissue perfusion. A new nomenclature for the quantity measured by these techniques is proposed, the local tissue cooling coefficient, a name which avoids any use of the term 'perfusion', in order to avoid unwarranted inferences regarding this quantity. The requirements for relating this quantity to the true tissue perfusion are presented, and possible applications of the local tissue cooling coefficient are reviewed. Finally, the techniques used by various investigators for normalizing SAR data are summarized and discussed, and a standard approach suggested.

Hot Temperature↗
PubMedDate not supplied

Relationships between thermal dose and heat-induced tissue and vascular damage after thermoradiotherapy of locally advanced breast carcinoma.

Twenty-four patients with locally advanced breast carcinoma were given thermoradiotherapy, and heat-induced damage to tissue and vasculature was studied in relation to thermal dose. Thermometry was performed using six to eight multi-point thermistor probes. Heat-induced damage was quantified by histopathological analysis of biopsies taken from the temperature probe locations shortly after treatment. Both tumour and normal tissue were found in the biopsies. Fraction of tissue and fraction of vessels with heat-induced damage were determined for the malignant and the normal tissue compartment separately, using stereological techniques. Clear relationships were found between these parameters and the largest thermal dose achieved in one heat fraction. The data were subjected to logit analysis, and the thermal doses (eqv. min at 43 degrees C) that caused massive necrosis in 50% of the tissue were calculated to be 116 +/- 31 for the malignant tissue compartment and 205 +/- 49 for the normal tissue compartment. Similarly, the thermal doses that caused damage to 50% of the vessels were found to be 63 +/- 34 and 144 +/- 46 for the malignant and the normal tissue compartment, respectively. Thus, the tumour tissue was more sensitive to heat than was the surrounding normal tissue, irrespective of whether necrosis or vessel damage was considered. This was probably a consequence of physiological and vascular differences between the two tissue compartments. Evidence for primary and secondary cell death was found both in the malignant and the normal tissue, although primary cell death probably was of minor importance in the normal tissue. The data indicate that selective heat-inactivation of tumour tissue is possible by external microwave hyperthermia of locally advanced breast carcinoma.

Blood Vessels↗
PubMedDate not supplied

3D rendering of SAR distributions from Thermotron RF-8 using a ray casting technique.

A comprehensive 3D visualization package developed for CT-based 3D radiation treatment planning has been modified to volume-render SAR data. The program accepts data from sequential thermographic thermometry measurements as well as calculated data from thermal models. In this presentation sample data obtained from a capacitive heating system 'Thermotron-RF8' is presented. This capability allows the generation of accurate standardized volumetric images of SAR and provides a valuable tool to better preplan hyperthermia treatments.

Evaluation Studies as Topic↗