Use of infrared thermometry to measure lavage and intravenous fluid temperature

A study was conducted to determine the accuracy of tympanic thermometers for measuring the temperature of warmed fluids in fluid bags and in tubing at the delivery site (ie, beside the intravenous [IV] catheter). One-liter 0.9% saline bags were warmed in a microwave oven. A thermocouple electronic temperature probe was then used to measure the reference temperature. The probe was inserted into each bag and bathed in the fluid. Temperature changes were recorded simultaneously over a 20-minute period using the probe and a First Temp Tympanic Thermometer (Intelligent Medical Systems, Inc, Carlsbad, CA). The warmed fluid was then allowed to run through microdrip IV tubing. Temperature of the effluent was measured in the tubing using the tympanic thermometer externally and the probe internally at the same point. The two measures were compared using linear regression and Student's t tests. Overall, the correlation between the two probes was r = 0.99 for both the fluid bags and the IV tubing. The overall mean differences were small, 0.7°C and 1.2°C for the bags and tubing, respectively, but they were statistically different (P > .05). Data were analyzed in three temperature ranges: <36°C, 36°C to 41°C, and >41°C. Again, small differences were found on the order of 1°C. It was concluded that infrared thermometry is an accurate method for measuring the initial and delivery temperature of warmed fluids. Although tympanic thermometer measurements were statistically different from reference readings in certain temperature ranges, these differences were small and not clinically significant. Tympanic thermometers can measure the temperature of warmed fluid bags and lavage and IV effluent adjacent to the catheter site, ensuring that hypothermic patients receive fluid at therapeutic temperatures.     

A comparison of infrared ear thermometry with electronic predictive thermometry in a geriatric setting

This project had three purposes: to determine the test/retest reliability of three thermometers--an infrared ear thermometer, an oral electronic predictive thermometer, and an oral mercury-in-glass thermometer (MIGT); determine the validity (accuracy) of the first two thermometers using the MIGT as the gold standard; and calculate the thermometers' sensitivity and specificity for detecting fever using 37.5 degrees C on the MIGT as the criterion. The MIGT had the best reliability, followed by the electronic predictive and infrared ear thermometer (for validity, the former was more accurate than the latter). Little difference existed in the latter two thermometers' sensitivity and specificity. However, the confidence intervals were wide, and further studies with larger samples need to be done to elucidate the thermometers' diagnostic properties.     

Reliability of infrared ear thermometry in the prediction of rectal temperature in older inpatients

Aims and objectives. To assess the capability of infrared ear thermometry accurately to predict rectal temperature in older patients. Background. Infrared ear thermometry is now commonly used for predicting body temperature in older patients. However, ear thermometry has been insufficiently evaluated in geriatric patients. Design. Prospective, convenience sample, unblinded study. Methods. All patients (or their guardians) gave informed consent. Patients hospitalised in a geriatric unit underwent sequential ear and rectal temperatures measurements using two different models of infrared ear thermometers (ThermoScan and Genius) and a rectal probe, respectively. After a brief otoscopic examination, ear temperatures were measured twice at both ears with each thermometer, the highest of four measurements being retained for analysis. The rectal temperature was the reference standard. Results. Hundred patients (31 males), aged 81 (SD 7) years completed the study. The mean rectal temperature was 37·3 °C (SD 0·7) °C (range 36·3–40·7 °C). Eighteen patients were febrile (rectal temperature ≥ 37·8 °C). The mean bias between rectal and ear temperatures as measured with the ThermoScan was –0·20 °C (SD 0·32) °C and the 95% limits of agreement were –0·83 °C and 0·42 °C (95% CI, –0·88–0·48 °C). Using the Genius, the corresponding figures were –0·56 °C (SD 0·39) °C, –1·32 °C and 0·20 °C (95% CI, –1·39–0·27 °C). After correction for bias, the ThermoScan predicted the level of fever with a maximum error of 0·7 °C (mean error 0·3 °C). Using the Genius, the maximum error and the mean error were 1·6 °C and 0·4 °C, respectively. Conclusions. Infrared ear thermometry can predict rectal temperature in normothermic and in febrile inpatients with an acceptable level of accuracy. However, the predictive accuracy depends on both operator technique and quality of instrumentation. Relevance to clinical practice. Proper technique (measuring in both ears) and optimal instrumentation (model of ear thermometer) are essential for accuracy.     

The random measurement of the transverse diameter of the fetal heart: a potential source of error

In a recent report it was suggested that the transverse diameter of the fetal heart measured randomly during the cardiac cycle from the real-time image was useful in predicting congenital heart disease (Jeanty P, Romero R, Cantraine F, et al: Fetal cardiac dimensions: a potential tool for the diagnosis of congenital heart disease. J Ultrasound Med 3:359, 1984). Comparing the above approach with M-mode measurements at end-diastole and end-systole suggests that random measurement of the transverse diameter is not appropriate for fetal cardiovascular evaluation because it could predict over 40 per cent of normal fetuses to have an "abnormally" increased cardiac dimension.     

Limitations of temperature measurement in the aural canal with an ear mould integrated sensor

Aural canal temperature measurement using an ear mould integrated sensor (T(ac)) might be a method suited for continuous non-invasive core temperature estimation in operational settings. We studied the effect of ambient temperature, wind and high intensity exercise on T(ac) and its ability to predict esophageal (T(es)) and rectal temperatures (T(re)). Seven subjects performed a protocol of rest at 21, 10 and 30 °C, followed by exercise and recovery at 30 °C. The subjects performed the protocol twice: with and without face-wind from halfway through the 30 °C rest period. Extra auricle insulation was applied at one side. Ambient temperature changes affected T(ac) significantly, while T(es) and T(re) remained stable. Insulating the auricle reduced but did not abolish this effect. Wind had an immediate cooling effect on T(ac) independent of auricle insulation. During exercise and recovery in 30 °C, T(ac) provided acceptable group predictions of T(re) in trials without wind (bias: -0.66 ± 0.21 °C covered, -1.20 ± 0.15 °C uncovered). Bias was considerably higher with wind, but variability was similar (-1.73 ± 0.11 °C covered, -2.49 ± 0.04 °C uncovered). Individual predictions of T(es) and T(re) showed more variation, especially with wind. We conclude that T(ac) may be used for core temperature assessment of groups in warm and stable conditions.     

Comparison of infrared versus contact thermometry for measuring skin temperature during exercise in the heat

The purpose of this study was to determine the validity of non-contact infrared thermometry to measure mean skin temperature in resting and exercising subjects in cold, thermo-neutral and hot environments. The subjects for the study were six healthy volunteers. Skin temperature was measured at three sites: the forearm, chest and calf on each subject using both contact thermistors and a non-contact infrared thermometer. Data were collected at rest and during exercise in three different air temperatures (15, 25 and 35 degrees C). The correlation of resting mean skin temperature using infrared thermometry and contact thermistors was r = 0.95, while the correlation obtained during exercise was r = 0.98. The results of the current study strongly suggest that infrared thermometry is a valid measure of skin temperature during rest and exercise in both hot and cold environments. It is hoped that the results of this study will encourage the use of non-contact infrared thermometry by both clinicians and exercise, environmental, and sleep researchers in the future.     

Accuracy of infrared ear thermometry in adult patients

Objective: To assess (1) the agreement between infrared ear thermometry and core reference temperature (in the pulmonary artery), (2) the agreement between measurements in the right and left ears, and (3) the screening validity of infrared tympanic thermometry in detecting rectal fever. Design: Temperatures were measured in both ears with an infrared thermometer, in one group of patients by simultaneous measurements with thermistors inserted in the pulmonary artery, esophagus, and rectum, and in the other group with a rectal glass-mercury thermometer. Setting: An intensive care unit and a department of internal medicine in a secondary care hospital. Patients and participants: Two samples: 16 adult patients admitted to the intensive care unit and 103 consecutive patients admitted to the department of medicine. Measurements: The major outcome measures were (a) the agreement between infrared ear thermometry and thermistor pulmonary artery temperature and (b) the sensitivity and specificity for detecting fever, using rectal measurement as reference. Results: Both rectal and esophageal thermistor measurements showed better agreement with the pulmonary artery reference temperature than single ear tympanic thermometry. The sensitivity and specificity of ear thermometry for detecting fever (≥38.0°C rectal reference) were 0.58 and 0.94, respectively. Double ear thermometry had a sensitivity of 0.61 and a specificity of 0.95, when using the mean value. Conclusions: Both rectal and esophageal thermistor measurements showed better agreement with pulmonary artery temperature than single ear thermometry. Using the mean of two ear measurements improves the agreement and screening validity for detecting fever by rectal temperature. If temperature measurements are critical, esophageal measurements achieve excellent agreement with pulmonary artery temperatures. Received: 15 November 1995 Accepted: 28 September 1996     

Digital instrument for measurement of aural acoustic immittance: a preliminary report

Development of techniques for measurement of aural acoustic immittance (AAI) is reviewed. Measurement characteristics of selected AAI instruments are compared. Real-ear data obtained with a digital instrument are presented. Review of data support the suggestion that digital AAI instruments promote development of quantitative measurement protocols with greater efficiency and power.     

Failure to perceive clinical events: An under-recognised source of error

Introduction

Attentional focus narrows as individuals concentrate on tasks. Missing an event that would otherwise appear obvious is termed a perceptual error. These forms of perceptual failure are well-recognised in psychological literature, but little attention has been paid to them in medicine. Cognitive workload and expertise modulate risk, although how these factors interplay in practice is unclear. This video-based experiment was designed to explore the hypothesis that perceptual errors affect clinicians.

Methods

142 volunteers with varying levels of experience of adult resuscitation were shown a short video depicting a simulated cardiac arrest. This video included a series of change-events designed to elicit perceptual errors. The experiment was conducted on-line, with participants watching the video and then responding via combinations of open-ended free-text and directed questioning.

Results

141 people experienced at least a single perceptual error. Even the most clinically significant event (disconnection of the patient's oxygen supply) was missed by three in four viewers. Although expertise was associated with increased likelihood of detecting an occurrence, even highly significant events were missed by up to two thirds of the most experienced observers.

Discussion

This study demonstrates, for the first time, that perceptual errors occur during healthcare-relevant scenarios at significant levels. Events such as an oxygen malfunction would meaningfully affect patient outcome and, although expertise conferred some advantages, events were still missed more often than not. Data acquisition is fundamental to good-quality situational awareness. These results suggest perceptual error may be a contributor to adverse events in practice.     

临床腋温测量方法的论证研究

目的 了解目前临床流程化测量腋温与教科书规定的规范化测量腋温的测量结果是否有差异.方法 对同一患者,在最接近的时间内先后采取流程化测量腋温与规范化测量腋温各1次,合计患者782例.结果 临床流程化测量腋温所测得的体温值与教科书规定的规范化测量腋温所测得的体温值比较差异无统计学意义.结论 建议规范临床流程化腋温测量的操作方法及管理措施,使流程化腋温测量做到数据科学化、操作高效化、服务人性化.     

Intragastric pH measurement using a novel disposable sensor

An unique disposable pH sensor molded into the end of a nasogastric tube was tested in twelve healthy human volunteers. A Spearman's rank corelation coefficient (r _s) of 0.90 was observed for the sensor and an indwelling miniature glass membrane electrode. The sensor did not correlate as well with aspirated stomach fluid (r _s=0.68). No sensor calibration was necessary and the sensors measured ±0.1 pH in laboratory pH buffers before and after the clinical study. Both bare and shielded disposable sensors closely agreed with a shielded miniature glass electrode.     

Volume measurement using the Polhemus FastSCAN 3D laser scanning: a novel application for burns clinical research

The Polhemus FastSCAN system offers a noncontact method of quantifying limb edema volume by combining laser scanning with 3D spatial orientation. The aim of this study was to investigate the reliability, validity and clinical utility of this assessment technique in the burn environment. Pilot Studies: Completed in order to develop a standardised scanning procedure. Intertester Reliability: Two testers each scanned 30 uninjured upper limbs. Intratester Reliability: One tester conducted repeated scans for burn survivors (n = 6). Validity: The scan volumes were compared with water displacement measures for all volunteers (n = 36). Intertester reliability was moderate for whole arm scans (R = .59; 95% confidence intervals [CI] = 0.28-0.78) and excellent with hand truncated (R = .95; 95% CI = 0.90-0.98; minimum detectable difference = 242.1 cm3). Intratester reliability was inconclusive (R = .72; 95% CI = -0.07-0.96) but qualitative assessment confirmed poorer quality scans. The FastSCAN system overstated the arm volume by 49.3 cm3 on average, but 95% limits of agreement when compared with water displacement demonstrated the limitations as a clinical or research tool in the burn environment. The Polhemus FastSCAN system provides a noncontact method of limb volume measurement. The reliability was good only with the hand removed from calculations. The accuracy of the system compared poorly with water displacement measures in the burn clinical environment. Using the currently available software and method, the change detectable by this technique was too large for monitoring the efficacy of acute burn edema interventions.     

新生儿体温背部测量法临床应用的可行性研究

目的 探讨新生儿体温背部测量法的科学性及可行性.方法 分别对100例新生儿体温进行7,10,30 min的腋窝、颌下、背部3种测量,与同时进行的3 min肛门测量的体温值进行对照比较.结果 新生儿体温背部测量法与其他部位测量法相同时间内所测体温值差异无统计学意义,P＞0.05.背部测量法7,10,30 min与肛门测量法(3 min)所得的体温值比较,均P＞0.05,差异无统计学意义.使用辐射抢救台和暖箱保暖的患儿背部测量体温7,10 min与肛门测量法所得的体温值比较均P＞0.05,差异无统计学意义.而30 min的腋窝测量法和颌下测量法与肛门测量法所得的体温值比较则P＜0.05,差异有统计学意义.30 min的背部测量法与肛门测量法所得的体温值比较P＞0.05,差异无统计学意义.结论 新生儿体温背部测量法可以与腋窝测量法、颌下测量法一样应用于护理量较大的临床新生儿科,背部测量法能较准确获得新生儿的真实体温,不受辐射抢救台和暖箱使用的影响,既可以避免患儿受凉,又可减轻护士1:作量,安全有效,方便实用,值得临床应用和推广.     

Fracture stiffness measurement using the orthometer: reproducibility and sources of error

OBJECTIVES: To elicit the reproducibility and the common sources of error in the use of the Orthometer, a commercially available goniometer based system, designed to measure the stiffness of healing fractures. DESIGN: A laboratory based study. BACKGROUND: The Orthometer is widely used to measure the progress of fracture healing in a quantitative manner. It has been shown previously that the bending stiffness of a fracture increases with healing and that a stiffness of 15 Nm/degree equates with the functional union of a tibial fracture. METHODS: The Orthometer was attached in a standard manner to nylon bars of known stiffness to determine the accuracy of the device. The Orthometer was then set up with changes in a single positional variable to assess the effect of this variable on the measurement accuracy. A number of different clinicians were asked to use the Orthometer before and after a simple training session and any improvements in the measurement accuracy were observed. RESULTS: Stiffness could be measured to within 10% or less of the true stiffness. Markedly different degrees of error were introduced with the various set-up variables. A simple training session improved clinician accuracy. CONCLUSIONS: Although the Orthometer does allow some degree of safety margin, it is essential that set-up is performed carefully, and that the clinician has been trained in the use of the device. RELEVANCE: Quantitative measurements of fracture healing have enormous potential benefits over manual and radiological methods of assessments. Provided these are carefully performed, the accuracy of these measurements is good.