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PubMedDate not supplied

Thermal protection with 5% dextrose solution blanket during radiofrequency ablation.

A serious complication for any thermal radiofrequency ablation is thermal injury to adjacent structures, particularly the bowel, which can result in additional major surgery or death. Several methods using air, gas, fluid, or thermometry to protect adjacent structures from thermal injury have been reported. In the cases presented in this report, 5% dextrose water (D5W) was instilled to prevent injury to the bowel and diaphragm during radiofrequency ablation. Creating an Insulating envelope or moving organs with D5W might reduce risk for complications such as bowel perforation.

Adrenal Cortex Neoplasms↗

PubMed2002

MR-guided laser-induced thermotherapy with a cooled power laser system: a case report of a patient with a recurrent carcinoid metastasis in the breast.

We report a case of a 52-year-old woman with a palpable recurrent metastasis of a neuroendocrine carcinoma to the upper outer quadrant of the right breast. For the treatment of this lesion, MR-guided laser-induced thermotherapy was performed with a cooled power laser system (Nd:YAG-Laser). An open 0.2-T MR unit was used for the monitoring of the laser energy delivery to the breast; thus, a thermosensitive fast low-angle shot 2D sequence for MR thermometry was used, so the ablation of the tumor and the increase of laser-induced necrosis could be interactively visualized with the repetitive use of this sequence. The postinterventional MR control exams 1 day and 4 months after laser-induced thermotherapy at the 1.5-T MR unit (Magnetom Symphony Quantum, Siemens, Erlangen, Germany) verified the complete ablation of the tumor without any signs of residual or relapsing tumor.

Breast Neoplasms↗

PubMed2002

Assessment of rhinological parameters for evaluating the effects of airborne irritants to the nasal epithelium.

OBJECTIVES: The initial contact area of inhaled toxins with the human body is the nasal mucosa. Upon irritation, nasal symptoms may occur that are well known as common viral infections of the airway and thus neglected by patients and physicians. Therefore, objective methods should be used to determine even minor irritative or inflammatory changes. METHODS: Objective methods to assess changes in the nasal epithelium include endoscopy, rhinomanometry, acoustic rhinometry, anemometry, thermometry, laser Doppler flowmetry, measurements of mucociliary transport time and ciliary beat frequency, analysis of nasal secretions, nasal cytology, and subjective (UPSIT, CCCRC, Sniffin Sticks) and objective (electro-olfactogram, olfactory event related potentials) and olfaction tests. RESULTS: Several different inhaled irritative and toxic substances, including metal dusts and steam, volatile organic substances, and inorganic gases, may harm the nasal epithelium. CONCLUSIONS: The objective evaluation of nasal functions should be used to assess effects of airborne irritants. For patients complaining of toxic effects, early diagnosis is important in the prevention of severe damage to the upper and lower airways.

Air Pollutants, Occupational↗

PubMed2001

Laparoscopic lumbar sympathectomy for lower-limb disease.

BACKGROUND: The standard procedure for sympathectomy is open surgery. The oblique retroperitoneal approach is popular because it provides good visibility, albeit at the expense of requiring a long skin incision. Chemical sympathectomy has been introduced as a less invasive means of achieving sympatholysis; however, this method is also associated with a significant incidence of incomplete block and transient denervation. Laparoscopic surgery is a new approach that simplifies various surgical procedures. The aim of our report was to evaluate the benefits of endoscopic retroperitoneal surgery for lumbar sympathectomies. METHODS: Between March 1997 and April 2000, seven patients underwent laparoscopic lumbar sympathectomy in our department (all men, with an average age or 45.1 years). The predominant presenting symptoms were unilateral pain at rest and lower-extremity coldness. Symphaectomy was performed using a retroperitoneal approach on six patients and an anterior transperitoneal approach on one patient. After laparoscopic lumbar sympathectomy, skin thermometry was carried out on all patients. RESULTS: The postoperative skin temperature of the affected leg rose to 36.6 +/- 0.5 degrees C, as compared to 33.8 +/- 0.8 degrees C preoperatively. After laparoscopic lumbar sympathectomy, none of the patients complained of neuralgia. All patients achieved sustained symptomatic relief, and no major postoperative complications were noted. CONCLUSIONS: Lumbar sympathectomy can be performed laparoscopically. Currently, our standard technique is the retroperitoneal approach. More clinical experience and long-term follow-up will ultimately determine if this will become the procedure of choice. However, we believe that a learning period is necessary for this technique to be fully mastered.

Adult↗

PubMed1997

Laparoscopic lumbar sympathectomy.

BACKGROUND: Lumbar sympathectomy retains a role in the treatment of patients with causalgia, Symptomatic vasospasm, and nonreconstructable arterial occlusive disease. Open surgical sympathectomy, with its attendant morbidities, remains the standard. Chemical sympathectomy has been introduced as a less invasive means of achieving sympatholysis. However, this has been associated with incomplete and transient denervation. METHODS: We present a series of five lumbar sympathectomies performed laparoscopically. RESULTS: All patients sustained symptomatic relief and no postoperative complications were noted. Postoperative skin thermometry and resistance measurements confirmed adequacy of sympatholysis. CONCLUSION: We conclude that lumbar sympathectomy can be performed laparoscopically. Our preferred technique is now the extraperitoneal approach. Such an approach combines the durability and reliability of standard open sympathectomy with the minimal invasiveness of laparoscopic surgery.

Adult↗

PubMed2001

Cytoreductive surgery combined with intraoperative chemo-hyperthermia and postoperative radiotherapy in the management of advanced pancreatic adenocarcinoma: feasibility aspects and efficacy.

BACKGROUND/PURPOSE: The aim of our study was to evaluate the feasibility and the efficacy of cytoreductive surgery (CS) with intraoperative chemo-hyperthermia in the management of advanced stage IVA (T4N0M0) pancreatic cancer. METHODS: From August 1995 through March 1996, seven patients with unresectable adenocarcinoma of the pancreas underwent CS, with preoperative chemotherapy (5-fluorouracil [FU] for 96 h), plus 45-Gy external beam postoperative irradiation with a 6-MeV linear accelerator (1.8 Gy per fraction, 5 days per week). A single session of intraoperative hyperthermia was performed with a waveguide-type applicator operating at 433 MHz, and temperature was measured by inserting a flexiguide needle catheter carrying a thermometry probe with three measuring points into the tumor. The tumor region was heated to 43 degrees C-45 degrees C for up to 60 min, while 5-FU 500 mg was injected simultaneously through the gastroduodenal artery into the splenic artery (intraoperative regional chemotherapy). RESULTS: Postoperative recovery was uneventful for all patients. After the combined treatment, there was a significant decrease in the values of both serum carcinoembryonic antigen (CEA; P = 0.017, Wilcoxon test) and carbohydrate antigen (CA)19-9 ( P = 0.016; Wilcoxon test), from 7.6 +/- 1.5 ng/ml CEA and 869.6 +/- 126.9 U/ml CA to 3.5 +/- 0.8 ng/ml CEA and 104.7 +/- 35.4 U/ml CA19-9. Moreover, there was a significant improvement ( P = 0.016; Wilcoxon test) in Eastern Cooperative Oncology Group performance status, pain score, and body mass index. The median overall survival was 18.5 (SE, 1.8) months. CONCLUSIONS: Our preliminary clinical results suggest the tolerability and the considerable potential advantage of using cytoreductive resection with preoperative chemotherapy, intraoperative chemo-hyperthermia, and external beam postoperative radiotherapy for the management of advanced adenocarcinoma of the pancreas.

Adenocarcinoma↗

PubMed1993

A new infrared tympanic thermometer in surgery and anesthesia.

We have evaluated a new infrared tympanic thermometer, IT-10, as an intraoperative temperature monitor in patients with or without open abdominal surgery. It determines temperature by measuring infrared radiation given off by a warm object. Temperatures measured with this device were closely correlated with those measured with rectal and bladder thermometries. We conclude that this new tympanic thermometer is safe, convenient, accurate, and easily usable in the clinical situation.

Journal Article↗

PubMed2005

Image guided interstitial laser thermotherapy: a canine model evaluated by magnetic resonance imaging and quantitative autoradiography.

OBJECTIVE: To determine the applicability and safety of a new canine model suitable for correlative magnetic resonance imaging (MRI) studies and morphological/pathophysiological examination over time after interstitial laser thermotherapy (ILTT) in brain tissue. MATERIAL AND METHODS: A laser fibre (Diode Laser 830 nm) with an integrated temperature feedback system was inserted into the right frontal white matter in 18 dogs using frameless navigation technique. MRI thermometry (phase mapping i.e. chemical shift of the proton resonance frequency) during interstitial heating was compared to simultaneously recorded interstitial fiberoptic temperature readings on the border of the lesion. To study brain capillary function in response to ILTT over time quantitative autoradiography was performed investigating the unidirectional blood-to-tissue transport of carbon-14-labelled alpha amino-isobutyric acid (transfer constant K of AIB) 12, 36 hours, 7, 14 days, 4 weeks and 3 months after ILTT. RESULTS: All laser procedures were well tolerated, laser and temperature fibres could be adequately placed in the right frontal lobe in all animals. In 5 animals MRI-based temperature quantification correlated strongly to invasive temperature measurements. In the remaining animals the temperature fibre was located in the area of susceptibility artifacts, therefore, no temperature correlation was possible. The laser lesions consisted of a central area of calcified necrosis which was surrounded by an area of reactive brain tissue with increased permeability. Quantitative autoradiography indicated a thin and spherical blood brain barrier lesion. The magnitude of K of AIB increased from 12 hours to 14 days after ILTT and decreased thereafter. The mean value of K of AIB was 19 times (2 times) that of normal white matter (cortex), respectively. CONCLUSION: ILTT causes transient, highly localised areas of increased capillary permeability surrounding the laser lesion. Phase contrast imaging for MRI thermomonitoring can currently not be used for reliable temperature readings in vivo. The suggested new canine model proved to be safe, accurate, easy to use, and provides clinical, radiographic, pathological and physiological correlations.

Aminoisobutyric Acids↗

PubMed2005

Sympathetic dysfunction as a temporary phenomenon in acute posttraumatic CRPS I.

OBJECTIVE: Sympathetic testing was carried out in patients in the acute phase of "complex regional pain syndrome type I" (CRPS I) shortly after trauma to the upper limb. Repeated measurements were used to detect changes in peripheral sympathetic function during the course of the disease. MATERIAL AND METHODS: In a busy trauma center, 10 consecutive patients who developed CRPS I following trauma or surgery of the upper limb were diagnosed according to the 1999 modified IASP diagnostic criteria for CRPS I. Clinical signs and symptoms and bilateral hand temperature (infrared thermometry) were recorded. Vasoconstrictor response to sympathetic provocation (inspiratory gasp, contralateral cooling) at the tip of the middle finger of both hands was measured employing laser Doppler flowmetry (LDF). Sympathetic reaction was quantified by the magnitude of blood flow decrease after provocation (SRF parameter). RESULTS: The diagnosis CRPS I could be established 63 days (46-72 days) post-injury. The mean follow-up time after diagnosis was 83+/-15 days. Pain measured by a visual analog scale (VAS 0-10) showed an average of 5.0+/-2.0 at the time of diagnosis and decreased to 1.7+/-1.9 at the last examination. Edema and active range of motion improved substantially during the follow-up period. On the ipsilateral hand marked sympathetic dysfunction was seen early after the onset of CRPS I (mean SRF parameter: 0.14+/-0.01), slowly returning to normal sympathetic reaction three months after the onset of symptoms (mean SRF parameter: 0.42+/-0.21). Diminished sympathetic function was seen even on the contralateral hand. CONCLUSIONS: Sympathetic dysfunction is regularly seen at the onset of CRPS I and normalizes during the course of the disease. This temporary phenomenon suggests a posttraumatic sympathetic deficit playing a decisive role in the genesis of CRPS I.

Acute Disease↗

PubMed2006

The Snellen human calorimeter revisited, re-engineered and upgraded: design and performance characteristics.

The measurement of whole body heat loss in humans and the performance characteristics of a modified Snellen whole body air calorimeter are described. Modifications included the location of the calorimeter in a pressurized room, control of operating temperature over a range of - 15 to + 35 degrees C, control of ambient relative humidity over a range of 20-65%, incorporation of an air mass flow measuring system to provide real time measurement of air mass flow through the calorimeter, incorporation of a constant load 'eddy current' resistance ergometer and an open circuit, expired gas analysis calorimetry system. The performance of the calorimeter is a function of the sensitivity, precision, accuracy and response time characteristics of the fundamental measurement systems including: air mass flow; thermometry and hygrometry. Calibration experiments included a calibration of the air mass flow sensor, the response of the thermometric measurement system for dry heat loss and the response of the hygrometric measurement system for evaporative heat loss. The air mass flow system was evaluated using standard differential temperature procedures to demonstrate linearity and sensitivity of the device. A novel procedure based on differential hygrometry was developed to ascertain the absolute calibration of air mass flow by resolving the unique system coefficient K. The results of the hygrometric calibration demonstrate the air mass flow response of the system is linear over the range of air mass flows from 6 to 15 kg min(-1). R(2) was 0.995. The average half response time (tR50) was 14.5 +/- 2.1 s. Similarly the results of the thermometric calibration demonstrate that the response of the apparatus is linear over the range of power input measured (coefficient of linearity R(2)=0.9997) with a precision of 0.72 W and an accuracy to within 0.36 W. The average (tR50) over all conditions was 6.0 +/- 1.9 min. In summary, modifications brought to the Snellen calorimeter have significantly improved the precision, accuracy and response time characteristics of the previous system while extending its operating range.

Air Conditioning↗

PubMed2002

Healing the diabetic wound and keeping it healed: modalities for the early 21st century.

The incidence of lower extremity wounds, infections, and amputations continues to increase worldwide. Fortunately, the past decade has seen a surge of activity in research into new modalities in wound healing and, even more recently, prevention. This article discusses the basic physiology of wound healing, with particular attention being paid to current and potential wound healing modalities. These include, among other modalities, discussions of bioengineered skin, hyaluronic acid, subatmospheric pressure therapy, growth factors, and endogenous cytokine stimulation. Emerging concepts targeting prevention through novel methods of patient empowerment, dermal thermometry, and computerized activity monitoring are also discussed.

Diabetes Complications↗

PubMed1990

Rapid and uniform electromagnetic heating of aqueous cryoprotectant solutions from cryogenic temperatures.

Devitrification (ice formation during warming) is one of the primary obstacles to successful organ vitrification (solidification without ice formation). The only feasible approach to overcoming either devitrification or its damaging effects in a large organ appears at present to be the use of some form of electromagnetic heating (EH) to achieve the required high heating rates. One complication of EH in this application is the need for warming within a steel pressure vessel. We have previously reported that resonant radiofrequency (RF) helical coils provide very uniform heating at ambient temperatures and low heating rates and can be modified for coaxial power transmission, which is necessary if only one cable is to penetrate through the wall of the pressure vessel. We now report our initial studies using a modified helical coil, high RF input power, and cryogenic aqueous cryoprotectant solutions [60% (w/v) solution of 4.37 M dimethylsulfoxide and 4.37 M acetamide in water and 50% (w/w) 1,2-propanediol]. We also describe the electronic equipment required for this type of research. Temperatures were monitored during high-power conditions with Luxtron fiberoptic probes. Thermometry was complicated by the use of catheters needed for probe insertion and guidance. The highest heating rates we observed using catheters occurred at temperatures ranging from about -70 to -40 degrees C, the temperature zone where devitrification usually appears in unstable solutions during slow warming. We find that in this range we can achieve measured heating rates of approximately 300 degrees C/min in 30- to 130-ml samples using 200 to 700 W of RF power without overheating the sample at any point. However, energy conservation calculations imply that our measured peak heating rates may be considerably higher than the true heating rates occurring in the bulk of our solutions. We were able to estimate the overall true heating rates, obtaining an average value of about 20 degrees C/min/100 W/100 ml, which implies a heating efficiency close to 100%. It appears that it should be possible to warm vitrified rabbit kidneys rapidly enough under high-pressure conditions to protect them from devitrification.

Animals↗

PubMed1994

Influence of protein ingestion on human splanchnic and whole-body oxygen consumption, blood flow, and blood temperature.

Splanchnic and whole-body oxygen uptake, blood flow, and blood temperature were studied in 10 healthy subjects before and during 2 hours after oral ingestion of 900 kJ of fish protein. Indirect calorimetry and catheter techniques were used, including blood thermometry in arterial, pulmonary arterial, and hepatic venous blood. After the meal, pulmonary oxygen uptake increased from a basal value of 272 +/- 11 to 332 +/- 23 mL/min. During the first postprandial hour, splanchnic oxygen uptake increased from 62 +/- 5 to 93 +/- 9 mL/min (+50%, P < .05), thereby accounting for 62% +/- 17% of the simultaneous increase in whole-body oxygen consumption. During the second postprandial hour, splanchnic oxygen uptake increased no further, whereas in the extrasplanchnic tissues the oxygen consumption increased, now accounting for the entire simultaneous increase in pulmonary oxygen uptake. Cardiac output increased from basal 6.4 +/- 0.4 to 7.5 +/- 0.5 L/min. Splanchnic blood flow changed little while the arteriohepatic venous oxygen difference increased from 46 +/- 3 to 54 +/- 4 mL/L. Arterial and hepatic venous blood temperatures increased by almost 0.3 degrees C, reflecting a considerable accumulation of heat, indicating a conversion into a positive thermal balance. It is concluded that after protein ingestion, (1) oxygen uptake increases mainly in the splanchnic organs during the first hour, and thereafter exclusively in the extrasplanchnic tissues; (2) the blood flow increases mainly in extrasplanchnic tissues; and (3) the blood temperature increases almost linearly, indicating an upward adjustment of the temperature setpoint in the central thermosensors.

Adult↗

PubMed1980

Respiratory water loss.

Two kinds of studies have been conducted in order to measure respiratory water loss: a single breath study of instantaneous variations in relative gas humidity of air expired during one respiratory cycle and a multibreath study of the average values of water vapor in air expired during several successive cycles of steady state ventilation. In the first case, relative gas humidity is computed from results obtained by thermometry and mass spectrometry; in the second case, average water vapor content of expired air is calculated from plethysmographic spirometry and expired water collection. Both experiments showed that mixed expired gas is not fully water saturated. The multibreath study showed that the mass of water lost per liter of ventilated gas is not a function of ventilation per se but rather increases as tidal volume rises and decreases as respiratory frequency diminishes. The mass of water lost per cycle of steady state ventilation increases with tidal volume so that mean expired gas volume may be considered as a mixture of dry gas and water saturated gas. The single breath study showed that unsaturated gas is expired in the first part of expirate followed by wet saturated gas in the second part. The numerical values given by the two kinds of studies are in close agreement.

Humans↗

PubMed1991

Blood-brain barrier alteration after microwave-induced hyperthermia is purely a thermal effect: I. Temperature and power measurements.

The effect of microwave-induced hyperthermia on the blood-brain barrier was studied in 21 Sprague-Dawley rats. Under sodium pentobarbital anesthesia, animals were place in a stereotactic frame, and an interstitial microwave antenna operating at 2450 MHz was inserted in a bony groove drilled parallel to the sagittal suture. Some antennae were equipped with an external cooling jacket. Temperature measurements were made lateral to the antenna by fluoroptical thermometry, and power was calculated from the time-temperature profile. Five minutes prior to termination of microwave irradiation, horseradish peroxidase (1 mg/20 g body weight) was injected intravenously. Extravasation of horseradish peroxidase was observed in brain tissue heated above 44.3 degrees C for 30 minutes and at 42.5 degrees C for 60 minutes. Microwave irradiation failed to open the blood-brain barrier when brain temperatures were sustained below 40.3 degrees C by the cooling system. Extravasation of blood-borne peroxidase occurred at sites of maximal temperature elevation, even when these did not coincide with the site of maximum power density. The data suggest that microwave-induced hyperthermia is an effective means for opening the blood-brain barrier and that the mechanism is not related to the nonthermal effect of microwaves.

Animals↗

PubMedDate not supplied

Is the endogenous antipyretic neuropeptide alpha-MSH responsible for reduced fever in aged rabbits?

The reduced febrile response in aged man has been noted since the beginning of clinical thermometry. Our previous research on aged rabbits and squirrel monkeys disclosed a similar reduced fever, presumably due to a decrease in central receptors for endogenous pyrogen. However, because central alpha-melanocyte stimulating hormone (MSH) appears to have a potent role in physiological control of fever, it may be that increased release of the peptide is responsible for the reduced febrile response in aged animals. To test this idea, antiserum specific to MSH was administered intracerebroventricularly to rabbits of known age. The antiserum given according to three schedules of treatment augmented fever caused by IV injections of interleukin-1 (IL-1) in young (less than 2 years) male and female rabbits. Aged female rabbits (3-5+ years) and females aged 2-3 years showed significant augmentation of fever only after pretreatment plus acute injection of antiserum. A single ICV injection of MSH (200 ng) reduced fever in all groups with the greatest antipyretic effect in the aged females. The results indicate that while aged rabbits have an increased antipyretic response to central MSH, binding of the endogenous peptide does not result in marked increases in fever in these animals. Thus, whereas a change in central MSH sensitivity may contribute to reduced fever in aged homeotherms, a reduction in central pyrogen receptors appears to be the most parsimonious explanation.

Aging↗

PubMed1982

Heating patterns induced by a 13.56 MHz radiofrequency generator in large phantoms and pig abdomen and thorax.

Heating patterns generated by a commercially available 13.5 MHz radiofrequency generator and induction coil hyperthermia system in human size phantoms and a 230 pound pig were studied using a multichannel computer-monitored thermometry system that is noninteractive in electromagnetic fields. The phantom studies were composed of synthetic muscle equivalent material and fresh tissue. The pig was heated in the regions of the upper abdomen and the midthorax, both under anesthesia and dead. The temperature was measured along fine penetrating catheters at 1 cm intervals in all experiments. In a homogeneous cylindrical phantom, under our measurement conditions, the temperature profile across the diameter is parabolic with marked superficial heating and essentially no central heating. In nonhomogeneous phantoms and in the pig, the symmetry of this profile was distorted but the basic pattern of marked superficial heating and nearly absent deep central heating remained. Blood flow in the living animal produced some thermal smoothing. It is considered probable that substantial radial temperature gradients will exist within eccentrically located human tumors heated with this device and that certain deep central tumors will be difficult or impossible to heat. Determination of its ultimate value for investigational; clinical hyperthermia studies will require accurate temperature mapping of tumors and normal tissues in various anatomic sites in comparison with other approaches to deep heating.

Abdomen↗

PubMed1983

Radiofrequency hyperthermia: the design of coil transducers for local heating.

Simple and complex coils have been designed and built for use as radiofrequency transducers for local and regional hyperthermia. The heating from such coils is produced by currents generated in the dielectric by the electromagnetic field radiated from the coil elements. The heating rate profile, as a function of phantom depth, is dependent upon the size and geometry of the coil, its proximity to the dielectric, and the transducer current. Since the fields of simple pancake coils are inhomogeneous, either complex geometries or some method of smoothing is required. A simple solution is to move the coil over the region to be heated or to use multiple applicators. However, many satisfactory heating patterns have been derived for stationary coils designed to heat well-defined subcutaneous volumes to a depth of 3-5 cm. Thermometry studies in static saline-gelatin phantoms demonstrate extensive heating ranges and flexibility since the coils couple with the dielectric through air.

Diathermy↗