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Got it, thanks!Body temperature is one of the four main vital signs that must be monitored to ensure safe and effective care. It is important to measure it accurately. To do this you need to choose an appropriate measurement device and to measure temperature using one of the common methods described below.
Most European countries use the rectal temperature measurement method because it is believed to be the most accurate one for determining body temperature. The duration of this procedure is less than a minute. Normal results are between 36.2 - 37.7°С.
In the post-Soviet space, Central Asia and the Middle East the axillary temperature measurement method is widespread. The thermometer is placed under the armpit and held there for several minutes until the result is determined. Temperature is measured at the axilla by placing the thermometer in the central position and adducting the arm close to the chest wall. Body readings of 35.3 - 36.8°С are considered normal. For greater accuracy, it is recommended to measure the temperature in the left armpit. Under the right armpit, the body temperature is lower by 0.1 - 0.3°С than in the left one.
The American continent is accustomed to measuring temperature orally. The oral cavity temperature is considered to be reliable when the thermometer is placed posteriorly into the sublingual pocket. To take the measurement, a digital thermometer is placed under the tongue. Normal values are 35.7 - 37.3°С, because the temperature of the oral cavity is on average 0.5°С higher than in the whole body.
And in Asia, non-contact infrared thermometers and screenings are popular. These devices have proven to be very helpful during the SARS outbreak and COVID-19 pandemic. Temperature can be measured in the ear, forehead and temple. The infrared thermometers sense infrared emissions radiating from the human body and objects.
You should know that there are some factors affecting accuracy of the temperature measurement. They include recent ingestion of food or fluid, having a respiratory rate >18 per minute, age, time of the day, physical activity, environment temperature, menstruation cycle phase, presence of skin secretion, clothes and smoking.
It is essential to use the most appropriate technique to ensure that temperature is measured accurately. Inaccurate results may influence diagnosis and treatment, lead to a failure to identify patient deterioration and compromise patient safety.
Whichever method you use to measure body temperature, our digital and infrared thermometers will always show you an accurate result and help you monitor your health and health of your loved ones.
Med Devices [Auckl]. 2016; 9: 301–308.
Published online 2016 Sep 1. doi: 10.2147/MDER.S109904
PMCID: PMC5012839
PMID: 27621673
Accuracy and precision of four common peripheral temperature measurement methods in intensive care patientsSimin Asadian,1 Alireza Khatony,1 Gholamreza Moradi,2 Alireza Abdi,1 and Mansour Rezaei3
Simin Asadian
1Nursing and Midwifery School, Kermanshah University of Medical Sciences
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Alireza Khatony
1Nursing and Midwifery School, Kermanshah University of Medical Sciences
Find articles by Alireza Khatony
Gholamreza Moradi
2Department of Anesthesiology
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Alireza Abdi
1Nursing and Midwifery School, Kermanshah University of Medical Sciences
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Mansour Rezaei
3Biostatistics & Epidemiology Department, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Author information Copyright and License information Disclaimer
1Nursing and Midwifery School, Kermanshah University of Medical Sciences
2Department of Anesthesiology
3Biostatistics & Epidemiology Department, Kermanshah University of Medical Sciences, Kermanshah, Iran
Correspondence: Alireza Khatony, Nursing and Midwifery School, Kermanshah University of Medical Sciences, Ashayer St., Isar Sq., Kermanshah 67146, Iran, Email moc.liamg@ynotahkA
Copyright © 2016 Asadian et al. This work is published and licensed by Dove Medical Press Limited
The full terms of this license are available at //www.dovepress.com/terms. php and incorporate the Creative Commons Attribution – Non Commercial [unported, v3.0] License [//creativecommons.org/licenses/by-nc/3.0/]. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.
Abstract
Introduction
An accurate determination of body temperature in critically ill patients is a fundamental requirement for initiating the proper process of diagnosis, and also therapeutic actions; therefore, the aim of the study was to assess the accuracy and precision of four noninvasive peripheral methods of temperature measurement compared to the central nasopharyngeal measurement.
Methods
In this observational prospective study, 237 patients were recruited from the intensive care unit of Imam Ali Hospital of Kermanshah. The patients’ body temperatures were measured by four peripheral methods; oral, axillary, tympanic, and forehead along with a standard central nasopharyngeal measurement. After data collection, the results were analyzed by paired t-test, kappa coefficient, receiver operating characteristic curve, and using Statistical Package for the Social Sciences, version 19, software.
Results
There was a significant meaningful correlation between all the peripheral methods when compared with the central measurement [P41.5°C] or decrease [>30°C] in body temperature can lead to death.2,3 Accurate determination of body temperature in critically ill patients is a fundamental requirement for initiating the proper process of diagnosis, and also therapeutic actions. For this purpose, measuring temperature with mercury, tape, digital, and tympanic thermometers are currently the commonly used methods.4 Each method has many advantages and some disadvantages, so selecting the proper thermometer and a more rigorous method is crucial.1 For measuring body temperature, eight locations have been considered, which include the nasopharynx, esophagus, pulmonary artery, rectum, axillae, tympanic membranes, legs, and bladder. Ideally, it is better, if possible, that measurement of temperature be done by a thermometer that is noninvasive, hygienic, convenient, and affordable, and also the measured temperature value would be close to the core body temperature eventually. In fact, the gold standard method for measuring the core body temperature is by way of the pulmonary artery approach,5 but this method has some restrictions such as being invasive and applicable only under special circumstances, in critical care wards and for unconscious patients.1,6 Another accurate method, which is accepted as the standard approach, is the nasopharyngeal method, which is noninvasive and in which the temperature is measured by inserting a sensitive probe into the external opening of the nose and directing it to the pharynx, between the nose and ears.5,7–9
Nowadays, the most common sites for measuring body temperature by local sensors include: oral cavity, tympanic membranes, pulmonary artery, axillae, rectum, esophagus, and gastrointestinal tract. Mouth, forehead, ears, and axillae are the most accessible parts of the body that have mostly been used by specialists in internal medicine to measure temperature; these sites show body temperature faster and easier, and in a noninvasive way, but the most appropriate method of measurement is still controversial.4,10
Several studies have been conducted for determining the most correct and accurate ways of measuring body temperature. In this regard, some authors have recommended the use of tympanic thermometers while others have not.1 Dzarr et al indicated that tympanic temperature is equal to core body temperature.11 However, Rubia-Rubia et al introduced axillary temperature measurement method as the best method and rejected the forehead approach.1 In this respect, Edelu et al recommended not using the axillary method.12 The results of Mazerolle et al’s study showed that the oral method could not reflect the core temperature of the body correctly,10 while Chue et al and Barnett et al announced that temperature measurement by tympanic and oral methods can correctly show the core body temperature.13,14
Aims and objectives
Considering the importance of an accurate method for assessing the body temperature of patients in the intensive care unit [ICU] by using a thermometer, and the controversial findings of the previous studies, this study was conducted for determining the accuracy and precision of the four methods of temperature measurement [oral, axillary, tympanic, and forehead] when compared to the standard nasopharyngeal method.
Methods
In an observational prospective study in 2011, the accuracy and precision of the four methods for measuring body temperature have been investigated. The study population included all hospitalized patients of the Imam Ali Hospital in Kermanshah, west of Iran. Imam Ali Hospital is a center where open heart surgeries are accomplished. This study was approved by ethics committee of research deputy of Kermanshah University of Medical Sciences. The setting of the study was the ICU where patients are admitted after surgery; there were 11 active beds in the ICU. The samples were recruited according to the convenience method. The sample size was calculated based on the sensitivity and specificity of previous studies4–6,8, using statistical formula, with 95% confidence interval and accuracy of 0.05. With regards to the sensitivity and specificity of previous studies that were between 64%–90%, so, we considered the maximum sample size of 237 patients which included 163 without fever and 74 with fever.
Inclusion criteria for sampling were: patients being conscious; having spontaneous breathing; at least 24 hours out from surgery; stable hemodynamic status; absence of dysrhythmia; lack of medications affecting blood vessels; not taking nonsteroidal anti-inflammatory drugs; not using corticosteroids; having no anti-fever medications since 4 hours ago; absence of infection in ears and mouth; no ear trauma or wax and no tympanic membrane perforation; not having any wound, trauma, or dressing at the temperature measurement sites; and absence of anatomical abnormalities in ears and mouth. The research instruments included data collection sheets and four types of thermometers [tympanic, forehead, mercury [for oral and axillary], and nasopharyngeal]. As the nasopharyngeal method had been used in various studies, it was considered to be the standard method.1,2 Furthermore, the results of these methods were similar to the other standard methods such as the pulmonary artery method.3 All the thermometers had been calibrated by the researcher before use for ensuring reliability. Repeated measurement of temperature at different time intervals, before and during data collection, was applied. The data collection sheet included questions about age, sex, blood pressure, duration of hospitalization, ambient temperature, and patient’s body temperature at the five different locations. It is noteworthy that we considered the cut-off point as 38°C, which was determined based on the Jahanpour et al’s study.4
For data collection, the written informed consent was taken from the patients, then the researcher referred to the Imam Ali hospital and visited the patients. In this study, all temperature measurements were performed by one researcher for reducing possible biases, and core body temperature was measured by an anesthesiologist, using a nasopharyngeal thermometer. For each patient, a special thermometer was used, and oral, axillary, tympanic, and forehead temperatures were measured simultaneously, then nasopharyngeal temperature was measured immediately afterwards. In general, on average, each patient’s temperature measurement process lasted 8 minutes.
For measuring the axillary temperature, the mercury thermometer [Jiangsu Company, Nanjing, People’s Republic of China] was used. The mercury thermometer, after shaking and lowering the mercury below 35°C mark, was placed in the axillary cavity and the patient’s body temperature was read after 5 minutes, and again at intervals of 2 minutes; the measurement was repeated again by placing the thermometer at the previous location and the values were recorded.
The oral temperature was measured by a mercury thermometer [Jiangsu Company]. After shaking the thermometer and lowering the mercury below the 35°C mark, it was placed for 5 minutes at the posterior part of the tongue then the numbers were monitored and recorded. This process was repeated after an interval of 2 minutes at the previous location and the values were recorded.
Measuring the tympanic temperature was done by a tympanic thermometer [Jinus Company, AZ, USA]. For this purpose, the researcher first pulled the patient’s auricle back and up for direct visualization of the ear canal, then the tip of the probe was inserted into the ear canal after covering it with disposable plastic, like an otoscope, and pushed forward slightly for preventing air effects on the screen. The number shown on the digital screen as ear temperature was recorded. The temperatures of both the right and left tympanic membranes were measured separately; each two times, within 2 minutes, and values were recorded. For each measurement, the probe of the tympanic thermometer was replaced.
Forehead temperature was measured using a strip thermometer, model BC200 [Taiwantrade company, Taipei, Taiwan], made in Taiwan. First, the researcher cleaned the forehead with a soft cotton swab dipped in alcohol, and after skin was dry, the strips were placed on the forehead, above the eyebrows. After 30 seconds, when the color bar was fixed, the displayed number was recorded as the temperature of the forehead. Two minutes later, the process was repeated again.
Nasopharyngeal standard temperature was measured using a sensor attached to a monitor [Space Labs Medical America Company, Issaquah, USA] and a disposable probe. For this purpose, a probe thermometer was inserted through the external hole of the nose to 5 cm posterior of the pharynx [between nose and ears] by the anesthesiologist, and after a reading was fixed on the screen, it was recorded. The probe was replaced for each patient.
The environment temperature of the patients’ rooms was measured on all days and it was between 27°C and 27.2°C. In this study, the cut-off point of fever was considered as ≥38°C by nasopharyngeal temperature measurement.
For sampling, the researcher referred to the intensive care ward of the Imam Ali Hospital, after obtaining permission from the Vice Chancellor of Research and Technology affiliated to Kermanshah University of Medical Sciences, and coordinating with the officials from the hospital. Data were collected after obtaining written informed consent from the participants and necessary explanation about the purpose of the study and assurance related to the confidentiality and anonymity of information were given to them.
Data collection sheets were completed by the researcher. The data were compiled by the Statistical Package for the Social Sciences, version 19, software [IBM Corporation, Armonk, NY, USA] and analyzed by descriptive and inferential statistics.15 The paired t-test was used for assessing the precision; determining the accuracy; measuring the sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV], and also kappa coefficient tests were done. The sensitivity is the results of division “number of true positive” / “number of true positive” + “number of false negatives”, and the specificity also calculated based on the division of “number of true negative” / “number of true negatives” + “number of false positives”. PPV specified the possibility of being a patient [having fever in this study] and NPV indicated the likelihood of being healthy [without fever in this study].16 The sensitivity and PPV were applied for determining the rate of real positive patients [with fever], and specificity and NPV were done for determining the extent of real negative patients [without fever]. Kappa coefficient was placed at five levels, from poor [