Development of a clinical thermometer calibration bath

https://www.ijhsr.org/IJHSR_Vol.13_Issue.3_March2023/IJHSR-Abstract18.html, 2023

BACKGROUND: Body temperature is a vital parameter in patient assessment. Fever is a common presentation in patients arriving at all health care setups. [1] It is a transient pathological state characterised by a disturbance in the hypothalamus thermoregulation system and, as a result, an increase in the body's temperature above the normal range. Normal body temperature values range from 36.5 to 37.4 °C depending on physiological variations, patient characteristics, and measurement sites. [2] Fever is a sign of underlying pathology – infection, infestation, inflammation, autoimmune diseases, malignancy, medication adverse reaction, intracranial haemorrhage or pulmonary embolism. Fever is also an important symptom in COVID-19 patients, typically appearing 12–14 days after exposure. And that made screening patients for elevated body temperature an essential initial triaging tool during the pandemic. [3] [4] A clinical thermometer is the equipment used for measuring body temperature. Several thermometers are available, each with its advantages, disadvantages, applicability, reliability and sensitivity. [5] Mercury-in-glass thermometers were the standard way to measure temperature for many years. They were taken off the market in the late 2000s because mercury is toxic to the environment. After that, many thermometers came into use, including digital, tympanic or axillary thermometers and non-contact infrared thermometers. Presently digital thermometers occupy the bedside at both homes and hospitals, including clinics. [6] [7] [8] The COVID-19 pandemic brought in, at large scales, the use of a non-contact infrared thermometer as a screening tool to measure body temperature. [9] [10] Our knowledge of the relative performance of different types of thermometers, including differences in temperature measured, is limited despite the essential role they play in clinical practice. So, it's essential to understand how different thermometers work and how accurate they are at making diagnoses. [11] [12] This is especially crucial considering the triage significance of fever measurement in clinical settings, especially emergency care, to refer patients to appropriate care pathways. OBJECTIVES: To evaluate the diagnostic accuracy of non-contactable infrared thermometers in comparison with mercury and digital thermometers. METHODOLOGY: The prospective observational study was conducted on 210 patients of both genders, of all age groups, presenting with or without fever to the ED of AIMS, Kochi, and a quaternary during the period from January to June 2022. The data we collected and statistically analysed from the study population are age, sex, presenting complaints, co-morbidities, heart rate, blood pressure, respiratory rate, SpO2, and body temperature being simultaneously measured with mercury, digital and non-contact infrared thermometers. The temperature of all patients was recorded using mercury, a digital thermometer placed in each axilla simultaneously, and a non-contactable infrared thermometer on the forehead. Mercury in glass thermometer was placed in axilla with the bulb of the thermometer in the tip of the axilla for 2 minutes. The digital thermometer was placed in a similar fashion in the other axilla and removed from the axilla after the beep was heard and temperature displayed was noted. The infrared thermometer is placed near the forehead or wrist, with a 5cm gap between the two. The trigger button is gently pressed, and the temperature shown on the LCD screen is recorded. RESULT: The study group included 53% males and 47% females. 58% belonged to the age group between 46 and 75 years, 30% between 16 and 45 years of age, 11% between 76 and 99 years and 1% below 15 years of age. Fever was present in 20.5% of the patients and the rest had other symptoms like vomiting, diarrhoea, cough, dyspnoea, fatigue, weakness, body pain and pedal oedema. 57% had two comorbidities, 29% were with more than 2 comorbidities while 14% had no known comorbidities. The body temperatures measured by mercury and digital thermometers were almost identical – Normal in 85.5%, above normal in 14% and below normal in 0.5%; but with a non-contact infrared thermometer, the same were 97.5%, 2.5% and 0% respectively. DISCUSSION: This study is highly relevant in the current scenario where the pandemic situation is almost over and a lot of institutions who invested in NCIT have started considering them for use as alternative devices for recording temperature. In our study, non-contact infrared thermometer failed in detecting fever in several affected patients, or misread normal temperature as elevated and was not capable of detecting hypothermia. Additional research is required to compare its accuracy and precision to other invasive and non-invasive core body temperature testing methods. The study finding of a rise in heart and respiratory rates in fever patients, though non-specific, concur with inferences from other similar studies. CONCLUSION: Our study concluded that the accuracy of non-contactable infrared thermometers is less reliable than mercury and digital thermometers for routine clinical practice. Though, the non-contact infrared thermometer was widely being used during the pandemic scenario, our study results do not favour its use other situations like the clinics, intensive care units or emergency departments.

Biology

The purpose of this study was to determine which thermometry technique is the most accurate for regular measurement of body temperature. We compared seven different commercially available thermometers with a gold standard medical-grade thermometer (Welch-Allyn): four digital infrared thermometers (Wellworks, Braun, Withings, MOBI), one digital sublingual thermometer (Braun), one zero heat flux thermometer (3M), and one infrared thermal imaging camera (FLIR One). Thirty young healthy adults participated in an experiment that altered core body temperature. After baseline measurements, participants placed their feet in a cold-water bath while consuming cold water for 30 min. Subsequently, feet were removed and covered with a blanket for 30 min. Throughout the session, temperature was recorded every 10 min with all devices. The Braun tympanic thermometer (left ear) had the best agreement with the gold standard (mean error: 0.044 °C). The FLIR One thermal imaging camera was the least acc...

2008

Accreditation is a means of determining the technical competence of laboratories to perform specific types of testing, measurement and calibration. Medical equipments require confirmation that they comply with specifications and safety regulations before they can be used in health care facilities. This paper presents guide lines to establish an Accredited Medical Equipment Calibration Laboratory in Egypt, based on the experience of the Medical Equipment Calibration Lab (MECL) of the Systems And Biomedical Engineering Department (SBME), Cairo University. A description of the calibration program and the requirements for calibration accreditation are explained. General overview of the MECL quality manual and other quality-related documentation is included.

Journal of Medical Devices, 2014

International Journal of Contemporary Pediatrics, 2017

Background: A wide variety of devices are available to record temperature from skin, oral or rectal mucosa and the tympanic membrane. The accuracy of different devices is varied and the primary objective of this study is to compare the diagnostic accuracy of digital thermometer against mercury in glass thermometer in children. The secondary objective was to determine the average time taken by the digital thermometer to record the temperature.Methods: This descriptive study was conducted in a pediatric ward at Institute of Child Health and Hospital for Children, Egmore, Chennai. In all 92 febrile children aged 1 month to 12 years admitted in the ward, temperature was measured at the time of admission using both digital and mercury in glass thermometers placed in each axilla after obtaining informed consent. Concordance and discordance of both measurements were determined using Pearson Correlation coefficient and Bland altman plot. Average time taken by digital thermometer to record t...

Regular Issue, 2020

A Calibration has been done for digital thermometer using a sensor and indicator method. The unit under test manufactured by Fluke with 54-II type and serial number 13160058, meanwhile, the standards that used are PT100 sensor from Omega and an indicator from Additel. The calibration result from 12 setpoints shows the average correction value as 0.61 ºC with uncertainty as 0.32 ºC and K factor as 2.0 at 95% confidence level

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 2020

Temperature is one of the crucial parameters in every aspect of life; therefore, it is essential to be able to measure it accurately. Temperature data acquisition utilizing a K-type thermocouple and MAX6675 module as cold junction compensation is being increasingly used by researchers because of its availability and relative ease of use. Ktype thermocouple and MAX6675 can be used as valid data acquisition if the sensors are properly calibrated. This research proposes a calibration method for K-type thermocouple and MAX6675 sensors based on Arduino microprocessor with DS18B20 thermistor as the reference, which has been previously calibrated with the ASTM-117C thermometer. Calibration was performed at ambient conditions utilizing the energy from the environment where four K-type thermocouple and MAX6675 sensors were calibrated alongside two DS18B20 sensors in ambient water for 24 hours. To increase the accuracy of the K-type thermocouple and MAX6675 sensors, simple mathematical methods were used in Arduino coding, thereby providing automatically calibrated values. After calibration using the proposed method, the sensors then were used in reading temperatures of ambient air and water. The result of this study is simple methods to improve the accuracy of K-type thermocouples and MAX6675 sensors to be used for reading temperature values in different working fluids using Arduino Microprocessor. The error value before calibration was 4.9% compared to 0.42% and 0.61% after calibration in ambient-water and ambient-air respectively.

Applied Optics, 1998

A new tympanic thermometer is analyzed and tested experimentally. An electrically calibrated pyroelectric detector of special configuration is employed to determine a person's body temperature. An energy-storage, power-supply-isolated capacitor is used as the electrical heating reference. The new thermometer design has an accuracy within Ϯ0.1°C with a 90% confidence and is immune to ambient temperature, detector aging, and parameter variations. An equivalent-circuit model is established in the analysis to account for the heat exchanges among the tympanum, the surroundings, and the detector as well as for the electrothermal behavior of the detector. The model provides effective simulation of the thermometer with PSPICE. Critical parameters governing the accuracy and the limitation of the tympanic thermometer are also pointed out by the simulation.

British Journal of Anaesthesia, 2009

Background. Accurate measurement of core temperature is a standard component of perioperative and intensive care patient management. However, core temperature measurements are difficult to obtain in awake patients. A new non-invasive thermometer has been developed, combining two sensors separated by a known thermal resistance ('double-sensor' thermometer). We thus evaluated the accuracy of the double-sensor thermometer compared with a distal oesophageal thermometer to determine if the double-sensor thermometer is a suitable substitute. Methods. In perioperative and intensive care patient populations (n=68 total), double-sensor measurements were compared with measurements from a distal oesophageal thermometer using Bland-Altman analysis and Lin's concordance correlation coefficient (CCC). Results. Overall, 1287 measurement pairs were obtained at 5 min intervals. Ninety-eight per cent of all double-sensor values were within +0.58C of oesophageal temperature. The mean bias between the methods was 20.088C; the limits of agreement were 20.668C to 0.508C. Sensitivity and specificity for detection of fever were 0.86 and 0.97, respectively. Sensitivity and specificity for detection of hypothermia were 0.77 and 0.93, respectively. Lin's CCC was 0.93. Conclusions. The new double-sensor thermometer is sufficiently accurate to be considered an alternative to distal oesophageal core temperature measurement, and may be particularly useful in patients undergoing regional anaesthesia.

2019

Calibration is one area in measurement where our country is still in the process of improvement. The absence of confirmed approaches and actions for identifying the features of calibration baths by numerous laboratories disallowed them to assess more the finest measurement ability and develop their accurateness. In recent advances in technology, there is now a way of providing the best measurement capability in temperature calibration by providing validated methods in characterizing calibration baths that contributes to the uncertainty of measurement of the calibrated thermometer and is therefore important to measure the extent of its contribution to the final uncertainty. This study adapted the process from obtainable and current methods. Platinum Resistance Thermometer (PRT-Isotech) and Standard Platinum Resistance Thermometer (SPRT-Hart) which are interfaced to Precision Digital Multimeters were used for measurements. Quite a few measurements were made at varying time durations i...