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PubMed2002

Improved coagulation with saline solution pretreatment during radiofrequency tumor ablation in a canine model.

PURPOSE: To determine whether pretreatment with local NaCl injection can increase radiofrequency (RF)-induced coagulation in a large animal model. MATERIAL AND METHODS: Multiple canine venereal sarcomas (n = 25) were implanted subcutaneously in eight mildly immunosuppressed dogs (25 mg/kg cyclosporin A twice daily). Tumors were incubated for 8-12 weeks to a diameter of 4.2-6.3 cm (5.1 cm +/- 0.7). Internally cooled RF ablation (1-cm tip; 12 min; pulsed technique; 2,000-mA maximum) was performed. Tumors were pretreated with 6 mL of 18%, 24%, or 36% NaCl injected intratumorally under direct ultrasound guidance after RF electrode insertion, and this treatment was compared to RF treatment without NaCl injection and to 36% NaCl injection without RF ablation. Impedance measurements and remote thermometry were performed. These measurements and resultant coagulation were compared. RESULTS: Significantly greater RF heating (73 degrees C +/- 11 degrees C at 20 mm) was observed when the tumors were treated with 24% or 36% NaCl pretreatment, compared to the 47 degrees C +/- 5 degrees C observed when 18% or no NaCl was injected (P <.02). In the 36% NaCl group, the entire tumor (5.2 cm +/- 0.8 diameter) was completely ablated in every case, with coagulation extending several centimeters into the surrounding tissues. By comparison, control tumors (without NaCl injection) contained coagulation measuring 3.1 cm +/- 0.2, surrounded by viable, well-perfused tumor (P <.01), and 36% NaCl alone produced 2.7 cm +/- 0.6 of patchy necrosis. CONCLUSIONS: Pretreatment with intratumoral injection of small volumes of highly concentrated NaCl markedly increases RF heating and coagulation in a large animal tumor model. The complete destruction of tumors 5 cm in diameter or larger suggests that this substantial increase may be achieved for tumor ablation in clinical practice.

Animals↗
PubMed2005

Electrokinetically based approach for single-nucleotide polymorphism discrimination using a microfluidic device.

In this work, we describe and implement an electrokinetic approach for single-nucleotide polymorphism (SNP) discrimination using a PDMS/glass-based microfluidic chip. The technique takes advantage of precise control of the coupled thermal (Joule heating), shear (electroosmosis), and electrical (electrophoresis) energies present at an array of probes afforded by the application of external electrical potentials. Temperature controllers and embedded thermal devices are not required. The chips can be easily and inexpensively fabricated using standard microarray printing methods combined with soft-lithography patterned PDMS fluidics, making these systems easily adaptable to applications using higher density arrays. Extensive numerical simulations of the coupled flow and thermal properties and microscale thermometry experiments are described and used to characterize the in-channel conditions. It was found that optimal conditions for SNP detection occur at a lower temperature on-chip than for typical microarray experiments, thereby revealing the importance of the electrical and shear forces to the overall process. To demonstrate the clinical utility of the technique, the detection of single-base pair mutations in the survival motor neuron gene, associated with the childhood disease spinal muscular atrophy, is conducted.

Cyclic AMP Response Element-Binding Protein↗
PubMed2006

Raman spectroscopy of benzenethiolates on nanometer-scale gold clusters.

Near-infrared (1064-nm) irradiation of neat solid samples of benzenethiolate monolayer-protected gold clusters (MPCs) yields strong, well-resolved Raman spectra of the thiolate groups, comparable to those obtained for the same groups adsorbed at roughened gold electrodes. These clusters are formulated as TOAZ[AuN(SPh)M]Z-, N >> M and Z = 3-6, with core diameters of 1.7 and 1.5 nm, and were characterized previously by X-ray scattering, mass spectrometry, infrared spectroscopy, optical spectroscopy, nuclear magnetic resonance, and elemental analysis [Price, R. C.; Whetten, R. L. J. Am. Chem. Soc. 2005]. Numerous previous attempts to obtain spectra on various MPCs yielded only diffuse luminescence bands, as did benzenethiolate MPC samples of TOA2[Au44(SPh)28]2-, with 1.1-nm core diameters. The clusters are free of excess tetraoctylammonium bromide (TOABr) from the synthetic procedure, containing only the necessary TOA+ to maintain charge balance. In situ thermometry, using the anti-Stokes/Stokes intensity ratios, indicated the sample temperature remained below the onset of thermal decomposition. The Raman spectra of the clusters bear a strong resemblance to those obtained for nonmetallic (Au(I)SPh)x polymer samples that are not in resonant absorption at the laser wavelength. The smaller of the two cores, nominally TOA6[Au110(SPh)62], shows clearly a band at 505 cm(-1) assigned to a S-S stretch, suggestive of a moiety resembling diphenyl disulfide on the cluster surface. These results are interpreted with reference to recent reports suggesting a substantial "reconstruction" of the outermost gold layer upon thiolate adsorption (SAM formation).

Journal Article↗
PubMed2001

Linear ablation using an irrigated electrode electrophysiologic and histologic lesion evolution comparison with ablation utilizing a non-irrigated electrode.

OBJECTIVES: To characterize the electrophysiologic and histologic sequelae of linear atrial ablation utilizing an irrigated electrode. To compare "irrigated" lesions with lesions deployed using the same electrode in a non-irrigated mode. BACKGROUND: Previous reports of radiofrequency catheter ablation using an irrigated electrode have emphasized its favorable effect on lesion depth. We hypothesized that electrode irrigation would also benefit linear ablation of smooth atrial myocardium, a relatively superficial target. METHODS: In healthy pigs, lesions were deployed in the right and left atria. Acutely, lesions resulting from ablation using an irrigated electrode, with radiofrequency energy titration guided by electrogram amplitude reduction, were compared to lesions using the same electrode without irrigation, with energy titration guided by electrode thermometry. Irrigated lesions were also assessed serially. RESULTS: Acutely, irrigated lesions formed complete conduction barriers and were uncomplicated. In contrast, non-irrigated lesions formed complete conduction barriers but were frequently complicated, exhibiting endocardial charring, barotrauma, and pericardial damage. The rate and pattern of histologic evolution of irrigated lesions were uniform throughout each lesion; right and left atrial lesions healed similarly. During healing, 90 % of lesions remained complete conduction barriers and 10 % manifested single discrete conduction gaps where viable appearing myocytes bridged the lesion. CONCLUSIONS: Complete, uncomplicated linear lesions could be reliably deployed in either atrium with an irrigated electrode. Not all lesions remained complete barriers to conduction during their histologic evolution. Lesions deployed with the same electrode in a non-irrigated mode were complete but frequently complicated.

Animals↗
PubMed2003

Arterial wall thermography.

An atherosclerotic plaque is considered vulnerable when it is at higher risk of inducing acute cardiac events. The early detection and follow-up of the vulnerable plaque are crucial to prevent these events from happening. To date there are no proven techniques to detect such a plaque. Arterial wall thermography, tracing the heat signature of the activated macrophages, is a new and promising method in this direction. However, the difficulties of applying such a method in vivo should not be neglected. Current science proposes several potential thermographic methods. They can be generally categorized as noninvasive and invasive. Magnetic resonance thermometry (MRT) is the most important noninvasive method. It is novel, accurate, and reproducible, but is unfortunately hampered by resolution limitations due to the size and motion of the target vessels. The "infrared" and the "contact-sensor" are the most important invasive thermographic methods. Mainly due to the difficulties of infrared radiation in penetrating the flowing blood, the contact thermographic methods seem to be the most feasible at present. The superiority of thermal mapping of the arterial wall versus the localized temperature measurements is clear. The use of multiple thermal sensors arranged around the vessel's circumference and the application of motorized catheter pullback, not only ensure a large area of coverage, but also enable us to build thermal maps and vascular thermoanatomical reconstructions by using modern computer technology. It is expected that arterial thermography will undoubtedly initiate debate, mainly concerning the most appropriate therapy for the vulnerable plaque. Data collection and correct interpretation are expected to lead us into making wise decisions.

Arteries↗
PubMed2001

NO reburning study based on species quantification obtained by coupling LIF and cavity ring-down spectroscopy.

NO reburning is studied in a low pressure (15 hPa) premixed flame of CH4-O2 seeded with 1.8% of NO. Measurements were carried out by using cavity ring-down spectroscopy (CRDS) and laser induced fluorescence (LIF) techniques. The temperature profile was obtained by OH-LIF thermometry in the A-X (0-0) band. The OH profile was determined by LIF and calibrated by single pass absorption. The NO concentration profile was obtained by LIF in the A-X (0-0) band and corrected for Boltzmann fraction and quantum yield variations. The absolute concentration profile was determined in the burned gases by CRDS allowing a direct experimental determination of the NO reburning amount. Finally CH and CN mole fraction profiles were obtained by CRDS by exciting rotational transitions in the B-X (0-0) bands of CH and CN around 387 nm. We found a peak mole fraction of 29 ppm for CH and 3.3 ppm for CN. This last result is in contrast with a previous study of W. Juchmann, H. Latzel, D. L. Shin, G. Peiter, T. Dreier, H. R. Volpp, J. Wolfrum, R. P. Lindstedt and K. M. Leung, XXVIIth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1998, p. 469, performed in a similar flame, which reported much lower levels of CN. In that study the absolute concentration of CN was indirectly obtained by LIF calibrated by Rayleigh scattering. In a second part, experimental species profiles are compared with predictions of the GRI 3.0 mechanism. Comparison between experimental and predicted profiles shows a good agreement particularly for CN and NO species. A qualitative analysis of NO reburning is then performed.

Journal Article↗
PubMed2003

Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems.

Joule heating is a significant problem in electrokinetically driven microfluidic chips, particularly polymeric systems where low thermal conductivities amplify the difficulty in rejecting this internally generated heat. In this work, a combined experimental (using a microscale thermometry technique) and numerical (using a 3D "whole-chip" finite element model) approach is used to examine Joule heating and heat transfer at a microchannel intersection in poly(dimethylsiloxane)(PDMS), and hybrid PDMS/Glass microfluidic systems. In general the numerical predictions and the experimental results agree quite well (typically within +/- 3 degree C), both showing dramatic temperature gradients at the intersection. At high potential field strengths a nearly five fold increase in the maximum buffer temperature was observed in the PDMS/PDMS chips over the PDMS/Glass systems. The detailed numerical analysis revealed that the vast majority of steady state heat rejection is through lower substrate of the chip, which was significantly impeded in the former case by the lower thermal conductivity PDMS substrate. The observed higher buffer temperature also lead to a number of significant secondary effects including a near doubling of the volume flow rate. Simple guidelines are proposed for improving polymeric chip design and thereby extend the capabilities of these microfluidic systems.

Computer Simulation↗
PubMed2004

Electroosmotic flow with Joule heating effects.

Electroosmotic flow with Joule heating effects was examined numerically and experimentally in this work. We used a fluorescence-based thermometry technique to measure the liquid temperature variation caused by Joule heating along a micro capillary. We used a caged-fluorescent dye-based microfluidic visualization technique to measure the electroosmotic velocity profile along the capillary. Sharp temperature drops close to the two ends and a high-temperature plateau in the middle of the capillary were observed. Correspondingly, concave-convex-concave velocity profiles were observed in the inlet-middle-outlet regions of a homogeneous capillary. These velocity perturbations were due to the induced pressure gradients resulting from axial variations of temperature. The measured liquid temperature distribution and the electroosmotic velocity profile along the capillary agree well with the predictions of a theoretical model developed in this paper.

Journal Article↗
PubMed2005

Performing microchannel temperature cycling reactions using reciprocating reagent shuttling along a radial temperature gradient.

This study develops a novel temperature cycling strategy for executing temperature cycling reactions in laser-etched poly(methylmethacrylate) (PMMA) microfluidic chips. The developed microfluidic chip is circular in shape and is clamped in contact with a circular ITO heater chip of an equivalent diameter. Both chips are fabricated using an economic and versatile laser scribing process. Using this arrangement, a self-sustained radial temperature gradient is generated within the microfluidic chip without the need to thermally isolate the different temperature zones. This study demonstrates the temperature cycling capabilities of the reported microfluidic device by a polymerase chain reaction (PCR) process using ribulose 1,5-bisphosphate carboxylase large subunit (rbcL) gene as a template. The temperature ramping rate of the sample inside the microchannel is determined from the spectral change of a thermochromic liquid crystal (TLC) solution pumped into the channel. The present results confirm that a rapid thermal cycling effect is achieved despite the low thermal conductivity of the PMMA substrate. Using IR thermometry, it is found that the radial temperature gradient of the chip is approximately 2 degrees C mm(-1). The simple system presented in this study has considerable potential for miniaturizing complex integrated reactions requiring different cycling parameters.

Equipment Design↗
PubMed2001

Radiofrequency energy-induced heating of bovine capsular tissue: Temperature changes produced by bipolar versus monopolar electrodes.

PURPOSE: To determine temperature changes associated with radiofrequency (RF) energy-induced heating of bovine capsular tissue using a bipolar RF electrode versus a temperature-controlled, monopolar RF electrode. TYPE OF STUDY: In vitro laboratory investigation using bovine capsular tissue. METHODS: Samples of bovine tissue were placed in a saline bath (37 degrees C) and RF energy was applied using bipolar and monopolar RF electrodes at manufacturer-recommended settings for tissue shrinkage. Fluoroptic thermometry was used to record temperatures on the tissue surface and at depths of 1 mm and 2 mm during continuous delivery of RF energy at 1, 2, 3, 4, 5, and 10 second time increments. RESULTS: The highest mean temperatures were recorded on the tissue surface, as follows (mean +/- SD; *P <.05, value compared with baseline): 1 sec 2 sec 3 sec 4 sec 5 sec 10 sec Bipolar 40.1 +/- 1.0* 48.2 +/- 4.7* 62.8 +/- 6.9* 76.0 +/- 7.6* 84.7 +/- 5.7* 94.7 +/- 1.9* Monopolar 39.0 +/- 0.7* 48.2 +/- 4.3* 67.7 +/- 7.0* 86.6 +/- 6.1* 93.8 +/- 2.7* 59.5 +/- 2.6* For the bipolar RF electrode, there was a strong linear relationship (R =.926) between mean surface temperatures versus time. The temperature-controlled, monopolar RF electrode did not appear to properly regulate the delivery of RF energy to maintain tissue temperatures at the selected level (i.e., 65 degrees C). The bipolar RF electrode produced a smaller temperature gradient (average difference, 9.2 degrees C) at the 1-mm tissue depth compared with the monopolar RF electrode (average difference, 14.6 degrees C). Temperature profiles at the 2-mm tissue depth were comparable for both types of RF electrodes. CONCLUSIONS: These data provide basic information pertaining to the temperature profiles produced by bipolar and monopolar RF electrodes applied to collagen-based tissue.

Animals↗
PubMed2000

Continuous measurement of core body temperature in preterm infants.

We tested a transcutaneous core temperature sensor using a method that relies on the principle of zero heat flow. We tested the hypothesis that transcutaneous and rectal temperatures would track within 0.3 degrees C of each other for >90% of the time. A thermistor was placed between the infant's abdomen or back and the incubator's or radiant warmer's mattress, or within the axilla, attached to the skin with a foam adhesive disk insulator. Thirty preterm infants were either placed on their abdomens or backs in a convective incubator or under a radiant warmer, and continuous transcutaneous and rectal temperatures were measured for 1 hour. There were no significant differences between abdominal and core temperatures or between axillary and core temperatures measured in double-walled convective incubators or in radiant warmers. The rectal-abdominal temperature difference was significantly less than the rectal-axillary difference (p < 0.02) in convective incubators, but not when the infant was placed prone under radiant warmers (p = 0.27). Transcutaneous thermometry is reliable for monitoring core body temperature as indicated by rectal temperature in stable preterm infants in a convective incubator.

Body Temperature↗
PubMed2000

Endohyperthermia--experimental evaluation of a new therapeutic approach for treatment of biliary carcinoma.

BACKGROUND AND STUDY AIMS: To improve the prognosis of patients with unresectable, locally advanced bile duct carcinoma, new treatment strategies need to be evaluated. Hyperthermia has been successfully applied as part of multimodal therapy in esophageal and rectal carcinoma. We performed in-vitro and in-vivo experiments with a new intraluminal hyperthermia system in the biliary tract. METHODS: A radiofrequency system (13.56 MHz, Endoradiotherm XERT-200A; Olympus Optical Co., Tokyo, Japan) was used with a special intraluminal microelectrode (diameter 4.5 mm, length 40 mm) covered by a silicone balloon with cooling water and a large counter electrode for focusing the electromagnetic field around the electrode. The heating capacity of the endohyperthermia unit was examined in vitro in a muscle-equivalent phantom (agar 4 %), in isolated livers of pigs and cows, as well as in vivo in anesthetized sheep. Continuous thermometry was done with thermosensors at the applicator surface, and with multichannel thermocouple probes in the environment of the applicator. RESULTS: Endohyperthermia induced a homogeneous heating of the phantom and the isolated liver bile duct preparation to a temperature > or = 40 degrees C in an area at least 10 mm in depth. After placement of the applicator into the common bile duct of anesthetized sheep, endohyperthermia led to a consistent and repeatable heating of the surrounding tissue to 40.5 +/- 0.5 degrees C at 1 cm distance, and 39.9 +/- 0.7 degrees C at 2 cm distance. Blood pressure, heart rate, and systemic temperature did not change in vivo. Histological examination of the bile duct showed superficial mucosal necrosis (depth 100-200 microm), microvascular damage with petechiae, congestion and edema of the bile duct wall and adventitia after hyperthermia treatment in vivo. CONCLUSIONS: The intraluminal endohyperthermia system produces consistent and repeatable heating of the surrounding tissue. Since effective thermal power can reach a depth of up to 2 cm, tumors may also be heated adequately.

Animals↗
PubMed2001

[Percutaneous laser ablation of malignant liver tumors].

PURPOSE: To present the technical data, methods and results of percutaneous laser ablation of malignant tumors. PATIENTS AND METHODS: In the period from June 1993 to April 2000 a collective of 600 patients with malignant liver tumors and liver metastases from different primary tumors were treated via MR-guided LITT. After sonographically or CT-guided puncture MR-compatible laser catheters were positioned. The tumor destruction was visualized via MR-thermometry. The checkup and the therapy accomplishment ensued in the course of an ambulant therapy concept. RESULTS: In the course of a local accomplished LITT of liver metastases and malignant liver tumors a local tumor control rate of 97.8 % was achieved. The complication rate was extremely low with a value of 2.2 % (1 441 treatments). The lethality rate was 0.1 %. The mean survival time referring to the whole patient collective was 47.7 months, in the case of liver metastases from a colorectal cancer a value of 46.8 months was achieved. CONCLUSION: MR-guided LITT is a local effective therapy with low morbidity in malignant liver tumors with a maximum quantity of 5 and a size of </= 5 cm.

Adult↗
PubMed2001

Ultrasound imaging of Nd:YAG laser-induced tissue coagulation in porcine livers.

AIMS: Absorption of laser light energy induces denaturation of proteins and thermocoagulation of irradiated tissue. Recently, MRI-guided laser coagulation in combination with MR thermometry was reported as a treatment of liver tumours. In the present study ultrasonographic imaging was evaluated for its suitability in laser induced tissue thermocoagulation. METHODS: Fresh porcine livers were used for ex vivo examinations. Placement of the laser catheter and tissue coagulation during laser light emission were online monitored by ultrasonography. Nd:YAG laser-induced tissue damage was evaluated by macroscopical and microscopical examinations of histological sections. RESULTS: During laser light emission a marked hyperdense signal enhancement was observed by ultrasonography which strongly correlated with the extent of macroscopic tissue damage. The size of laser-induced coagulation zone depended on both the power setting and total energy delivered. Carbonization of the tissue surrounding the laser tip is a limiting factor because of laser light absorption. However our data indicate that using appropriate laser energy and exposure time prevent carbonization although carbonization can not be visualized by ultrasonography. CONCLUSIONS: It is concluded from the present ex vivo studies that laser coagulation can be effectively performed under ultrasonographic guidance.

Animals↗
PubMed2005

[Percutaneous thermal ablation of renal neoplasms].

Due to modern examination techniques such as multidetector computed tomography and high-field magnetic resonance imaging, the detection rate of renal neoplasms is continually increasing. Even though tumors exceeding 4 cm in diameter rarely metastasize, all renal lesions that are possible neoplasms should be treated. Traditional treatment techniques include radical nephrectomy or nephron-sparing resection, which are increasingly performed laparoscopically. Modern thermal ablation techniques such as hyperthermal techniques like radiofrequency ablation RFA, laser induced thermal ablation LITT, focused ultrasound FUS and microwave therapy MW, as well as hypothermal techniques (cryotherapy) may be a useful treatment option for patients who are unfit for or refuse surgical resection. Cryotherapy is the oldest and best known thermal ablation technique and can be performed laparoscopically or percutaneously. Since subzero temperatures have no antistyptic effect, additional maneuvers must be performed to control bleeding. Percutaneous cryotherapy of renal tumors is a new and interesting method, but experience with it is still limited. Radiofrequency ablation is the most frequently used method. Modern probe design allows volumes between 2 and 5 cm in diameter to be ablated. Due to hyperthermal tract ablation, the procedure is deemed to be safe and has a low complication rate. Although there are no randomized comparative studies to open resection, the preliminary results for renal RFA are promising and show RFA to be superior to other thermal ablation techniques. Clinical success rates are over 90 % for both, cryo- and radiofrequency ablation. Whereas laser induced thermal therapy is established in hepatic ablation, experience is minimal with respect to renal application. For lesions of more than 2 cm in diameter, additional cooling catheters are required. MR thermometry offers temperature control during ablation. Microwave ablation is characterized by small ablation volumes and plays a role as a coagulation tool during resection. Focused ultrasound is the only non-invasive method, but it is still experimental.

Catheter Ablation↗
PubMed2005

[Evaluation of sympathicolysis after continuous brachial plexus analgesia using laser Doppler flowmetry in patients suffering from CRPS I].

OBJECTIVE: The aim of this study was to evaluate continuous brachial plexus analgesia in terms of pain relief and sympathicolysis in patients suffering from CRPS I. METHODS: A detailed clinical examination comprised measurement of temperature changes (Infrared Thermometry), pain rating (VAS scale) and assessment of peripheral sympathetic nervous function using laser Doppler flowmetry. A total number of 12 patients (mean age: 56 +/- 9 years, range: 30 to 69 years) received continuous brachial plexus analgesia after placing a catheter in the perineurial sheath of the brachial plexus through an axillary approach. Prior to continuous analgesia (Morphin 0.04 mg/ml, Clonidin 1.5 microg/ml, Bupivacaine 0.0625 %) running at 4 ml/h a test dosis of 20 ml Bupivacaine 0.25 % was applied to establish brachial plexus block. RESULTS: After an equilibration period of 2 hours, consecutive pain measurements revealed sufficient pain relief in 9 out of 12 patients (75 %) with a mean pain rating dropping from 4.7 +/- 0.68 to 1.59 +/- 1.02 (p < 0.001). Pain reduction was accompanied by a significant temperature increase from -0.78 degrees C to 1.7 degrees C (p < 0.05). However measurement of sympathetic function by laser Doppler flowmetry revealed that no significant sympathicolysis occurred. CONCLUSIONS: The study shows that clinical investigation of temperature change is not reliable in the evaluation of sympathicolysis. This is of special interest in patients who are suspected of having sympathically maintained pain (SMP) and are treated by brachial plexus analgesia.

Adult↗
PubMed1996

[Early clinical experiences with MR-guided laser-induced thermotherapy (LITT) of liver metastases in preoperative care].

PURPOSE: To evaluate the LITT-induced changes with the aid of MRT and correlate these with histopathological findings. MATERIAL AND METHODS: Five patients with solitary colorectal liver metastases were treated by means of MR-guided LITT before liver resection. Application time and energy of the Nd:YAG laser (1064 nm) was 10-20 minutes and 4.5-8.8 W. MRT monitoring during the LITT was carried out with temperature-sensitive T1 weighted sequences (FLASH-2-D, turbo FLASH). The extent of the induced necrosis as seen on MR was compared with the unfixed specimen and with the histopathological findings. RESULTS: The extent of necrosis visible by MRT correlated with the histopathological findings with an accuracy of 95.3% +/- 4.2%. Following single treatments (three cases) the metastases suffered a reduction of 24%-55% of their original volume. In two patients a second application produced laser-induced necrosis of 78% and 98% of volume. In these two patients a temperature sound was used for measuring regional heating and showed an exact correlation with MR thermometry. CONCLUSION: The results of pre-operative MR-guided LITT indicates the potential of this form of treatment for obtaining reproducible tumor necrosis of liver metastases.

Aged↗
PubMedDate not supplied

[Regional hyperthermia with systemic chemotherapy in children and adolescents: feasibility and clinical follow-up of 34 intensively pretreated patients with prognostically unfavorable tumor diseases].

Temperature elevation for a few degrees (degrees C) increases significantly the cytotoxicity of several antineoplastic drugs under experimental conditions. An isolated elevation of the tumour temperature, which is possible since a few years, might be able to improve local tumour control without increasing the systemic toxicity. This study was performed to examine the feasibility of regional hyperthermia with systemic chemotherapy in pediatric patients. The special interests were the level of temperatures that could be achieved as well as the degree of toxicity and undesired side effects. Furthermore there was some hope to attain local tumour control in cases with very poor prognosis. 34 patients up to 18 years were treated in Munich and Essen until the end of 1992. 21 suffered of local relapse, in 11 cases it was the 2nd up to the 7th relapse. In another 11 cases the indication for the combined treatment was tumour progress or non-response to previous therapy. 33 patients were pretreated by aggressive chemotherapy, 20 patients had received radiotherapy before. In 28 cases the tumour was located in the pelvis. The heating device that we use is commercially available. It is based on external electromagnetic radiation which induces heat by absorption within the tissue. Since the temperature distribution inside the tumours is very heterogeneous thermometry is necessary which can only be performed invasively. For this sake we use closed tip catheters which are inserted into the tumour by puncture or surgically. The catheters remain in place for the whole treatment duration of several weeks. Chemotherapy was performed in treatment cycles (3.4/patient) mainly using etoposide, ifosfamide, and carboplatin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗