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PubMed1999

[Ear thermometry from the otologic viewpoint].

Tympanic thermometry (TT) detects infrared emissions reaching a probe placed in the ear canal directed toward the tympanic membrane. This has been reported to be an ideal site for clinical temperature measurements. TT provides results rapidly, taking only one second. It is clean, safe, and there is no mucous membrane contact. Studies have primarily focused on the use of TT in pediatric office and emergency room settings. In the literature published to date, the otological viewpoint has not played an important role. Specially there is no systematic investigation of the influence of cerumen on TT. Twenty patients were examined. All of them had a complete obstruction of the auditory canal by cerumen. TT was performed before and after the removal of cerumen. It was found to have a significant impact on the ear temperature reading. After the removal, the temperature was higher by 0.5 degree C. In conclusion, one should consider that there can be a systematic error when using TT to determine body temperature. Nevertheless there are some important advantages compared to other methods of temperature measurements. Especially in the hands of physicians and nurses TT is accurate and can be recommended. However, at home in the hand of non-professionals there are some limitations and restrictions, particular when used in children. Further studies will have to be performed with a focus on otological problems and to determine the accuracy of TT in the non-professional user.

Adult↗
PubMed2005

Paramagnetic thermosensitive liposomes for MR-thermometry.

MR-thermometry methods have been developed for the guidance and control of thermal therapies such as thermal ablation or regional hyperthermia. However, they are limited to the measurement of temperature changes and, thus, cannot be used to assess absolute temperature values. Paramagnetic thermosensitive liposomes are innovative contrast agents offering the potential to overcome these limitations. They are composed of a gadolinium- or manganese-based compound enclosed by a phospholipid membrane with a distinct gel-to-liquid crystalline phase transition temperature (Tm). At this temperature, the phospholipid membrane changes from a gel-phase to a liquid-crystalline phase which is associated with an increased transmembrane permeability towards solutes and water. Under these conditions, both types of paramagnetic thermosensitive liposomes demonstrate a significant increase in longitudinal (T1) relaxivity, attributed to the release of paramagnetic material from the liposome and/or to the increased water exchange rate between the liposome interior and exterior. Paramagnetic thermosensitive liposomes have already been successfully studied in animal models and have demonstrated a clear correlation between tissue temperature changes and signal intensity changes in MRI. Nevertheless, before entering clinical trials they have to be studied in more detail with regard to dose, pharmacokinetics and toxicity.

Contrast Media↗
PubMedDate not supplied

The historical development of thermometry and thermal imaging in medicine.

Human body temperature has been an important part of medicine since very early times. However, until the thermometer was developed in the 16th century measurement was not possible. Some 200 years later, Wunderlich laid the foundation for clinical thermometry, and temperature charts became commonplace throughout the world. More recently thermal imaging has broadened the understanding of body surface temperature in health and disease. Standards for computer-assisted infrared imaging are well developed, and present-day fast high-resolution imaging is less expensive and more reliable than it was 40 years ago.

History, 17th Century↗
PubMed1991

Programmable sweep radiometer system as a new tool for non-invasive thermometry.

A new microwave radiometer system consisting of a frequency sweep-type radiometer and an ultra wideband antenna has been developed. A computer-controlled radiometer system covers the input frequency range from 0.5 GHz to 8 GHz. It can be used not only as a multispectral radiometer system whose frequencies can be chosen freely, but also as a frequency sweep-type radiometer system whose frequency is continuously swept during measurement. When an antenna is attached to a forearm, the sensitivity of the radiometer system exceeds 0.09 degree C when the integration time is 3 sec and IF bandwidth is 500 MHz. The new microwave radiometer system may be utilized for non-invasive thermometry of the human body.

Humans↗
PubMed1982

Photoluminescent thermometry based on europium-activated calcium sulphide.

A photoluminescent thermometer, based on the transient emission response of a europium-activated calcium sulphide phosphor, is described in detail. This optical thermometry system has special advantages for temperature measurements in microwave and RF fields and potential application in electromagnetically induced clinical hyperthermia. A laboratory system has been constructed which utilises a fibreoptic probe with external diameter 0.8 mm. A system temperature resolution of 0.1 degree C has been achieved in the range 37-47 degrees C.

Calcium↗
PubMed1999

Fast spectroscopic imaging for non-invasive thermometry using the Pr[MOE-DO3A] complex.

The praseodymium complex of 10-(2-methoxyethyl)-1,4,7,10-tetraaza-cyclododecane-1,4,7-tr iacetate) was evaluated as a temperature-sensitive contrast agent using the temperature dependence (approximately 0.12 ppm degrees C(-1)) of the chemical shift of its methoxy side group signal. Pr[MOE-DO3A] was employed in combination with spectroscopic imaging (SI) methods for the determination of spatially resolved 2D and 3D temperature distributions in phantoms. Conventional SI and fast echo planar SI sequences (EPSI) were implemented on a 4.7 T MR imaging system fulfilling the demands for non-invasive thermometry (NIT) with respect to thermal and temporal resolution, being <1 degree C and <20 s total measuring time, respectively. The sequences are based on a fast spin echo SI method taking into account the very short relaxation times of the Pr complex methoxy group (T1 = 28 ms, T2 = 13 ms) and its chemical shift difference (-24 ppm) from water. Calibration curves were measured in a uniformly heated water phantom and 2D SI methods were applied to dynamic heating experiments. The average differences between the temperatures measured via fibreoptic thermometer and those derived from the spectroscopic methods were < or =0.2 degrees C. Furthermore, 3D EPSI experiments with a 16 x 16 x 16 matrix size yielded temperature measurements within 17 s from voxels of size 3 x 3 x 3 mm3.

Calibration↗
PubMed1998

New trends in thermometry for the patient in the ICU.

Modern engineering and space-age technology introduce innovations in thermometry at a crucial time in critical care history. Today's assessment and care decisions are based, in part, on emerging scientific evidence about thermoregulatory responses. Accurate body temperature measurements and the correct interpretation of their meaning are crucial for competent care. Confusion exists as to which instrument or site is "ideal." Interpretation of temperature correlations, between temperature sites or without consideration of linearity, has little meaning outside the clinical context. This article discusses hemodynamic and thermal conditions influencing regional body temperatures along with instrument accuracy, reliability, linearity, precision, safety, comfort, and need for staff training.

Bias↗
PubMed1999

Real-time control of focused ultrasound heating based on rapid MR thermometry.

RATIONALE AND OBJECTIVES: Real-time control of the heating procedure is essential for hyperthermia applications of focused ultrasound (FUS). The objective of this study is to demonstrate the feasibility of MRI-controlled FUS. METHODS: An automatic control system was developed using a dedicated interface between the MR system control computer and the FUS wave generator. Two algorithms were used to regulate FUS power to maintain the focal point temperature at a desired level. RESULTS: Automatic control of FUS power level was demonstrated ex vivo at three target temperature levels (increase of 5 degrees C, 10 degrees C, and 30 degrees C above room temperature) during 30-minute hyperthermic periods. Preliminary in vivo results on rat leg muscle confirm that necrosis estimate, calculated on-line during FUS sonication, allows prediction of tissue damage. CONCLUSIONS. The feasibility of fully automatic FUS control based on MRI thermometry has been demonstrated.

Animals↗
PubMed1992

Infrared ear thermometry.

Many hospitals are considering using infrared (IR) ear thermometers (also called tympanic membrane thermometers) as an alternative to traditional temperature-measurement devices. IR technology allows users to quickly and noninvasively measure body temperature by inserting a directional probe into the ear canal. For infection control, ear thermometers offer the advantages of not contacting mucous membranes and eliminating the need for special handling procedures. For use on unconscious patients or those who are otherwise unwilling or unable to cooperate with traditional techniques, IR ear thermometers offer a more comfortable and less stressful method of temperature taking for both patients and nurses, especially where rectal temperatures are used. The recent entry into this market by major companies and distributors and the release of several new IR ear thermometers have helped to further stimulate interest in this technology. However, a complete transition to IR ear thermometers throughout the hospital may not be necessary and should be made only after these devices have been successfully used in selected clinical locations, such as emergency departments, critical care areas, recovery areas, and labor and delivery rooms. Clinical users must be familiar with the technique needed for temperature measurement with these instruments and understand the differences between temperatures taken in the ear canal and those obtained from traditional sites. In the following article, we first present an overview of clinical thermometry, describing traditional temperature-measurement sites and devices. We then discuss the advantages and disadvantages of using the ear canal, including the tympanic membrane (TM), as a site for temperature measurement. In addition, we guide readers in determining the usefulness of IR ear thermometers.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed2006

Infrared tympanic thermometry in comparison with other temperature measurement techniques in febrile children.

OBJECTIVE: : To determine whether infrared tympanic thermometry (ITT) measurements more accurately reflect core body temperatures than axillary, forehead, or rectal measurements during fever cycles in children. DESIGN: : Prospective cohort study. SETTING: : Pediatric and cardiac intensive care units at a tertiary care children's hospital. PATIENTS: : Critically ill children <7 yrs of age with indwelling bladder catheters. INTERVENTIONS: : Simultaneous temperatures were recorded during both febrile and nonfebrile periods using ITT, indwelling bladder (core), axillary, forehead, and indwelling rectal measurements in 36 children. MEASUREMENTS AND MAIN RESULTS: : Overall ITT measurements were 0.03 +/- 1.43 degrees F less than core temperature measurements. In comparison, rectal, forehead, and axillary measurements averaged 0.62 +/- 1.44, 0.56 +/- 1.81, and 1.25 +/- 1.73 degrees F less than core temperature measurements. ITT measurements had better agreement with core measurements during increasing and decreasing temperature cycles. Receiver operating characteristic analysis performed on increasing and decreasing temperature cycle data revealed that ITT measurements performed well, with an area under the curve of 0.855 (95% confidence interval, 0.797-0.913) in comparison with rectal measurement area under the curve of 0.777 (95% confidence interval, 0.701-0.853), forehead measurement area under the curve of 0.710 (95% confidence interval, 0.715-0.888), and axillary measurement area under the curve of 0.664 (95% confidence interval, 0.579-0.750). CONCLUSIONS: : ITT measurements more accurately reflect core temperatures than any other measurement site during febrile and nonfebrile periods in children. ITT measurements are a reproducible and relatively noninvasive substitute for bladder or rectal measurements in febrile children.

Body Temperature↗
PubMed2004

Comparison of the temporal artery and rectal thermometry in children in the emergency department.

OBJECTIVE: Rectal thermometry, the criterion standard of temperature measurement in young children, has numerous disadvantages. This study examined the agreement between rectal versus a new temporal artery professional model (TAPM) thermometer and rectal versus a home device temporal artery consumer model (TACM) thermometer, investigated if the TAPM can safely screen for rectal fever, and determined if parents can detect rectal fever using the TACM. DESIGN, OUTCOME MEASURES, AND SUBJECTS: In this cross-sectional agreement emergency department study, 327 children <24 months of age had their temperature measured rectally and by the TAPM and TACM by a single nurse and using the TACM by the parents. Agreements were analyzed by the Bland Altman plots. Temperature cutoff to detect rectal fever > or =38.0 degrees C and > or =38.3 degrees C with sensitivities of > or =90% and > or =95%, respectively, was determined for the TAPM. RESULTS: The mean difference between the rectal minus TAPM was -0.19 degrees C +/- 0.66 degrees C, and minus the TACM home device, it was +0.11 degrees C +/- 0.66 degrees C. The sensitivities of TAPM temperature of > or =37.7 degrees C to detect rectal fever > or =38.0 degrees C and > or =38.3 degrees C were 90% (95% confidence interval: 0.83; 0.94) and 97% (95% confidence interval: 0.92; 0.99), respectively. The parents detected 67% and 73% of rectal fevers 38.0 degrees C and > or =38.3 degrees C, respectively. CONCLUSIONS: The TAPM thermometer cannot replace the rectal. However, TAPM temperature of <37.7 degrees C can be safely used as a screen to exclude rectal fever > or =38.3 degrees C in infants 3 to 24 months of age. The TACM home device has insufficient ability to detect rectal fever. A multicenter trial is needed to validate these results across multiple emergency departments and numerous observers.

Child, Preschool↗
PubMed2003

Remote thermometry to avoid complications in radiofrequency ablation.

Percutaneous image-guided radiofrequency ablation (RFA) of tumors has the potential risk for thermal damage to nearby normal collateral tissues. Thus, the goal of creating a sufficient area of tumor necrosis must be weighed against the risk for injury to collateral tissues. In this study, remote thermistors were used to monitor temperatures near collateral structures during tumor RFA. Four unique cases are described. When temperature-sensitive structures are near the target lesion, remote thermometry could further increase the safety of this evolving minimally invasive procedure.

Aged↗
PubMed2006

Noise thermometry with two weakly coupled Bose-Einstein condensates.

Here we report on the experimental investigation of thermally induced fluctuations of the relative phase between two Bose-Einstein condensates which are coupled via tunneling. The experimental control over the coupling strength and the temperature of the thermal background allows for the quantitative analysis of the phase fluctuations. Furthermore, we demonstrate the application of these measurements for thermometry in a regime where standard methods fail. With this we confirm that the heat capacity of an ideal Bose gas deviates from that of a classical gas as predicted by the third law of thermodynamics.

Journal Article↗
PubMed2000

Dual-mode antenna design for microwave heating and noninvasive thermometry of superficial tissue disease.

Hyperthermia therapy of superficial skin disease has proven clinically useful, but current heating equipment is somewhat clumsy and technically inadequate for many patients. The present effort describes a dual-purpose, conformal microwave applicator that is fabricated from thin, flexible, multilayer printed circuit board (PCB) material to facilitate heating of surface areas overlaying contoured anatomy. Preliminary studies document the feasibility of combining Archimedean spiral microstrip antennas, located concentrically within the central region of square dual concentric conductor (DCC) annular slot antennas. The motivation is to achieve homogeneous tissue heating simultaneously with noninvasive thermometry by radiometric sensing of blackbody radiation from the target tissue under the applicator. Results demonstrate that the two antennas have complimentary regions of influence. The DCC ring antenna structure produces a peripherally enhanced power deposition pattern with peaks in the outer corners of the aperture and a broad minimum around 50% of maximum centrally. In contrast, the Archimedean spiral radiates (or receives) energy predominantly along the boresight axis of the spiral, thus confining the region of influence to tissue located within the central broad minimum of the DCC pattern. Analysis of the temperature-dependent radiometer signal (brightness temperature) showed linear correlation of radiometer output with test load temperature using either the spiral or DCC structure as the receive antenna. The radiometric performance of the broadband Archimedean antenna was superior compared to the DCC, providing improved temperature resolution (0.1 degree C-0.2 degree C) and signal sensitivity (0.3 degree C-0.8 degree C/degree C) at all four 500 MHz integration bandwidths tested within the frequency range from 1.2 to 3.0 GHz.

Biomedical Engineering↗
PubMedDate not supplied

Infrared tympanic thermometry for neonatal temperature assessment.

OBJECTIVE: To investigate the accuracy and precision of infrared tympanic thermometer use with neonates by comparing with axillary and rectal measurements. DESIGN: Descriptive, comparative study. SETTING: Newborn nursery of a tertiary-level perinatal center. SUBJECTS: Thirty-four full-term newborns. INSTRUMENTS: Infrared thermometers were used to collect tympanic temperatures. An electronic thermometer was used to collect axillary and rectal temperatures. RESULTS: There was no significant difference between tympanic and axillary temperatures. The range of variation (95% CI) was +/- 0.7-.9 degrees C. The mean difference between tympanic and rectal measurements was 0.4 degrees C. The range of variation was +/- 0.7-0.75 degrees C. Right ear measurements produced the best approximation of axillary temperature, and protected ear measurements produced the best approximation of rectal temperature. The protected ear was 0.2-0.3 degrees C higher than the exposed ear. CONCLUSIONS: There was more variation between tympanic versus axillary and tympanic versus rectal measurements than between axillary and rectal measurements. Tympanic thermometry may be useful for rapid screening of neonatal temperature, but its usefulness for monitoring unstable neonates remains in question.

Axilla↗
PubMedDate not supplied

Infrared tympanic thermometry in the evaluation of pediatric acute otitis media.

OBJECTIVE: The reliability of infrared tympanic thermometry (ITT) in children and the effect of acute otitis media (AOM) on ITT are unsettled. This study assessed the effect of AOM on ITT and the utility of ITT in the diagnosis of AOM. METHODS: 520 consecutive children, aged 6 months to 6 years, presenting to the ED of an urban teaching hospital were eligible for this prospective observational study. Nurses recorded oral or rectal reference temperatures (RefTs) and bilateral ITT temperatures upon presentation. Emergency physicians were blinded to the ITT temperatures. AOM was diagnosed according to published clinical criteria. RESULTS: Among 520 patients, 108 had unilateral AOM and 78 had bilateral AOM. In patients with unilateral AOM, the infected ears were warmer (I = 100.4 +/- 1.8 degrees F) than the uninfected ears (U = 100.3 +/- 1.8 degrees F, p = 0.035). However, the disparity in TM temperatures in infected and uninfected ears with unilateral AOM (I - U = 0.2 +/- 0.9 degrees F) was similar to the difference between right and left ears in those without AOM (R - L = 0.1 +/- 0.8 degrees F, p = 0.60). Compared with patients without AOM, patients with AOM demonstrated no significant elevation of ITT temperatures over RefTs (I - RefT = -0.8 +/- 1.2 degrees F in AOM; ITT - RefT = -0.8 +/- 1.2 degrees F in non-AOM; p = 0.94). This study had >99% power to detect a 1.0 degrees F difference for all groups compared. CONCLUSIONS: Infrared tympanic temperature are not helpful in diagnosing AOM in children. AOM has little direct effect on ITT temperatures.

Acute Disease↗
PubMed2006

Does dermal thermometry predict clinical outcome in diabetic foot infection? Analysis of data from the SIDESTEP* trial.

The purpose of the study was to assess in patients with a diabetic foot infection (DFI), whether differences in skin temperature of the affected foot as compared to the corresponding site on the contralateral foot using dermal thermometry (DT) correlates with infection severity and clinical outcome. As part of the SIDESTEP DFI study, investigators took DT measurements at baseline and the discontinuation of intravenous therapy (DCIV) and performed a systematic evaluation of the infected limb to calculate a wound score. We compared the skin temperature differential between the limbs at the two assessments and determined the correlation between this value and surrogate markers of inflammation and the clinical response to treatment. Among patients enrolled in SIDESTEP, 332 were fully evaluable. The mean temperature differential between the limbs was 2.81 +/- 5.75 degrees F at baseline and 2.43 +/- 4.84 degrees F at DCIV (mean change: -0.37; 95% confidence interval (CI): -0.98, 0.23; P= 0.225). Skin temperature differential at baseline did not correlate with white blood cell count, level of C-reactive protein or erythrocyte sedimentation rate or the infection severity score (r= 0.058, 0.148, -0.002, 0.067, respectively). We observed no overall trend between surface temperature differential at baseline and clinical outcome at DCIV, but patients with a skin temperature differential of > or =10 degrees F at baseline had a significantly lower clinical response than those whose differential was <10 degrees F (81.4% versus 94.3%; difference 12.9%; 95% CI: 3.5, 27.3%, P= 0.007). While there was no overall relationship between skin temperature and poor clinical outcome, there may be a threshold effect in DT (<10 degrees F versus >10 degrees F) between the limbs at baseline that predicts outcome of therapy.

Diabetic Foot↗