The diagnostic accuracy of digital, infrared and mercury-in-glass thermometers in measuring body temperature: a systematic review and network meta-analysis

Comparison of continuous temperature measurement methods in the intensive care unit: standard bladder catheter measurements versus non-invasive transcutaneous sensors

The purpose of this study was to compare a wearable system for body core temperature measurement versus bladder and tympanic thermometers in an intensive care setting. The question was, if continuous non-invasive sensors in the intensive care unit represent an alternative to current standard methods of invasive continuous bladder temperature measurement methods?Between May and September 2023, a comparative investigation involving 112 patients was conducted in a 20-bed surgical intensive care unit to assess various temperature probes, including those placed in the tympanic tube, bladder, and skin. To achieve this, a wireless non-invasive sensor system provided by greenTEG AG, Switzerland, was affixed to different body locations (clavicular and lateral chest) of each catheterized patient (equipped with a temperature probe) admitted to the intensive care unit. Furthermore, tympanic temperatures were recorded at specified intervals. The measurement duration ranged from a minimum of six hours to a maximum of six days, resulting in the analysis of a total of 355 simultaneous temperature measurements.In this study, a wearable temperature measurement system attached to two different body sites revealed a consistent negative bias compared to bladder temperature. In addition, the measurements were particularly influenced by body constitution. The tested system in all patients showed a mean absolute error (MAE) of 0.45 °C for the lateral chest and 0.50 °C for the clavicular position. Tympanic measurements had a mean absolute error of 0.35 °C. In patients with body mass index (BMI) ≥ 25 the MAE increased to 0.5 °C for the lateral chest and 0.56 °C for the clavicular position. In contrast, the tympanic measurement had a reduced MAE of 0.32 °C, which is well below this threshold when compared to bladder measurements.In conclusion the investigated system did not meet the clinically relevant acceptance criteria and showed low precision in correctly identifying fever episodes compared to invasive temperature probes, however its main advantage lies in its continuity and non-invasiveness. This makes it a potential alternative to intermittent tympanic measurement devices. In this study we were able to show, that in at least one subset of patients, the non-invasive and continuous device demonstrated a precision comparable to tympanic measurements.The accuracy of all non-invasive methods was lower than in previous studies, suggesting that the use of bladder temperature as reference and user related variations may have introduced additional errors.

Exploring Thermal Dynamics in Wound Healing: The Impact of Temperature and Microenvironment

Exploring the critical role of thermal dynamics in wound healing, this manuscript navigates through the complex biological responses initiated upon wound infliction and how temperature variations influence the healing trajectory. Integrating biothermal physics, clinical medicine, and biomedical engineering, it highlights the significance of thermal management in wound care, emphasizing the wound microenvironment's division into internal and external domains and their collaborative impact on tissue repair. Innovations in real-time wound temperature monitoring, especially through intelligent wireless sensor dressings, are spotlighted as transformative, enabling precise wound condition management. The text underscores the necessity for further research to elucidate thermal regulation's molecular and cellular mechanisms on healing processes. It advocates for standardized protocols for localized heating treatments, integrating them into personalized wound care strategies to enhance therapeutic outcomes, improve patient well-being, and achieve cost-effective healthcare practices. This work presents a forward-looking perspective on refining wound management through sophisticated, evidence-based interventions, emphasizing the interplay between thermal dynamics and wound healing.

Fever assessment in children under five: Are we following the guidelines?

BACKGROUND

Fever is a common cause of medical consultation and hospital admission, particularly among children. Recently, the United Kingdom's National Institute for Health and Care Excellence (NICE) updated its guidelines for assessing fever in children under five years of age. The efficient assessment and management of children with fever are crucial for improving patient outcomes.

AIM

To evaluate fever assessment in hospitalized children and to assess its adherence with the NICE Fever in under 5s guideline.

METHODS

We conducted a retrospective cohort review of the electronic medical records of children under five years of age at the Department of Pediatrics, Salmaniya Medical Complex, Bahrain, between June and July 2023. Demographic data, vital signs during the first 48 h of admission, route of temperature measurement, and indications for admission were gathered. Fever was defined according to the NICE guideline. The children were divided into five groups according to their age (0-3 months, > 3-6 months, > 6-12 months, > 12-36 months, and > 36-60 months). Patients with and without fever were compared in terms of demography, indication for admission, route of temperature measurement, and other vital signs. Compliance with the NICE Fever in the under 5s guideline was assessed. Full compliance was defined as > 95%, partial compliance as 70%-95%, and minimal compliance as ≤ 69%. Pearson's χ2, Student's t test, the Mann-Whitney U test, and Spearman's correlation coefficient (rs) were used for comparison.

RESULTS

Of the 136 patients reviewed, 80 (58.8%) were boys. The median age at admission was 14.2 [interquartile range (IQR): 1.7-44.4] months, with the most common age group being 36-60 months. Thirty-six (26.4%) patients had fever, and 100 (73.6%) were afebrile. The commonest age group for febrile patients (> 12-36 months) was older than the commonest age group for afebrile patients (0-3 months) (P = 0.027). The median weight was 8.3 (IQR: 4.0-13.3) kg. Patients with fever had higher weight than those without fever [10.2 (IQR: 7.3-13.0) vs 7.1 (IQR: 3.8-13.3) kg, respectively] (P = 0.034). Gastrointestinal disease was the leading indication for hospital admission (n = 47, 34.6%). Patients with central nervous system diseases and fever of unknown etiology were more likely to be febrile (P = 0.030 and P = 0.011, respectively). The mean heart rate was higher in the febrile group than the afebrile group (140 ± 24 vs 126 ± 20 beats per minute, respectively) [P = 0.001 (confidence interval: 5.8-21.9)] with a positive correlation between body temperature and heart rate, r = 0.242, n = 136, P = 0.004. A higher proportion of febrile patients received paracetamol (n = 35, 81.3%) compared to the afebrile patients (n = 8, 18.6%) (P < 0.001). The axillary route was the most commonly used for temperature measurements (n = 40/42, 95.2%), followed by the rectal route (n = 2/42, 4.8%). The department demonstrated full compliance with the NICE guideline for five criteria: the type of thermometer used, route and frequency of temperature measurement, frequency of heart rate measurement, and use of antipyretics as needed. Partial compliance was noted for two criteria, the threshold of fever at 38 °C or more, and the respiratory rate assessment in febrile patients. Minimal compliance or no record was observed for the remaining three criteria; routine assessment of capillary refill, temperature reassessment 1-2 h after each antipyretic intake, and refraining from the use of tepid sponging.

CONCLUSION

This study showed that fever assessment in hospitalized children under five years of age was appropriate, but certain areas of adherence to the NICE guideline still need to be improved.

Temperature Monitoring in Children: An Agreement Study

Background:

Noncontact infrared thermometer (NCIT) measures temperature rapidly and noninvasively. It is commonly used at forehead, but other potential sites such as axilla and abdomen are yet to be explored. We assessed agreement of temperature recordings of axillary temperature by glass mercury thermometer (the “gold standard”) with axillary temperature by the digital thermometer as well as with NCIT at forehead, axilla, mid abdomen, and at right hypochondriac areas.

Methods:

Neonates and children below 5 years admitted in neonatal and pediatrics wards were enrolled in the study through convenience sampling. For each participant, temperature was measured using NCIT at forehead, mid abdomen, right hypochondrium, and right axilla as well as using digital thermometer at right axilla and using glass mercury thermometer at right axilla. The agreement between methods was presented as mean difference (95% limits of agreement) using Bland-Altman analysis.

Results:

Total 400 temperature readings were taken for each method from 132 participants. There was a good agreement between mercury axillary with digital axillary in both the groups, that is, neonates and children (>1 month to 5 years) (Mean difference [95% limits of agreement] = –0.046 [–0.26 to 0.169]°C and –0.028 [–0.183 to 0.128]°C, respectively). While for all the methods using NCIT, there was a poor agreement with mercury axillary temperature in both the groups.

Conclusion:

Agreement between axillary temperatures using digital and glass mercury thermometers was good, while agreements between the axillary temperature using glass mercury thermometer with NCIT readings at different sites were poor in neonates and children below 5 years.

Setting up a three‐stage pre‐endoscopy triage during the coronavirus disease 2019 pandemic: A multicenter observational study

Objectives

Between May and July 2021, the coronavirus disease 2019 (COVID‐19) pandemic led to a sharp surge in community transmission in Taiwan. We present a three‐stage restructuring process of pre‐endoscopy triage at the beginning of the pandemic, which can support urgent endoscopic procedures while protecting endoscopy staff.

Methods

The pre‐endoscopy triage framework was set up with three checkpoints at the hospital entrance, outpatient department, and endoscopy unit, with a specific target patient population and screening methods. Relevant data included the number of endoscopic procedures performed, outpatient department visits, and performing screening methods such as temperature measurement, travel, occupation, contact, and clustering history checking, polymerase chain reaction assay, and rapid antigen test.

Results

Forehead temperature measurement and verification of travel, occupation, contact, and clustering history provided rapid, easy, and early mass screening of symptomatic patients at the hospital entrance. During the pandemic, outpatient department visits and endoscopic procedures decreased by 37% and 64%, respectively. The pre‐endoscopy screening methods used displayed regional variations in COVID‐19 prevalence. Among 16 endoscopy units with a community prevalence of ≥ 31.04 cases per 100,000 residents, 12 (75%) used polymerase chain reaction assay and four (25%) used rapid antigen test to identify asymptomatic patients before endoscopy. Of 6540 pre‐endoscopy screening patients, 15 (0.23%) tested positive by laboratory testing. No endoscopy‐related nosocomial COVID‐19 infections were reported during the pandemic.

Conclusions

We present a three‐stage pre‐endoscopy triage based on the local laboratory capacity, medical resources, and community prevalence. These measures could be useful during the COVID‐19 pandemic.

A Comparative Study of Forehead Temperature and Core Body Temperature under Varying Ambient Temperature Conditions

When the ambient temperature, in which a person is situated, fluctuates, the body's surface temperature will alter proportionally. However, the body's core temperature will remain relatively steady. Consequently, using body surface temperature to characterize the core body temperature of the human body in varied situations is still highly inaccurate. This research aims to investigate and establish the link between human body surface temperature and core body temperature in a variety of ambient conditions, as well as the associated conversion curves.

METHODS

Plan an experiment to measure temperature over a thousand times in order to get the corresponding data for human forehead, axillary, and oral temperatures at varying ambient temperatures (14-32 °C). Utilize the axillary and oral temperatures as the core body temperature standards or the control group to investigate the new approach's accuracy, sensitivity, and specificity for detecting fever/non-fever conditions and the forehead temperature as the experimental group. Analyze the statistical connection, data correlation, and agreement between the forehead temperature and the core body temperature.

RESULTS

A total of 1080 tests measuring body temperature were conducted on healthy adults. The average axillary temperature was (36.7 ± 0.41) °C, the average oral temperature was (36.7 ± 0.33) °C, and the average forehead temperature was (36.2 ± 0.30) °C as a result of the shift in ambient temperature. The forehead temperature was 0.5 °C lower than the average of the axillary and oral temperatures. The Pearson correlation coefficient between axillary and oral temperatures was 0.41 (95% CI, 0.28-0.52), between axillary and forehead temperatures was 0.07 (95% CI, -0.07-0.22), and between oral and forehead temperatures was 0.26 (95% CI, 0.11-0.39). The mean differences between the axillary temperature and the oral temperature, the oral temperature and the forehead temperature, and the axillary temperature and the forehead temperature were -0.08 °C, 0.49 °C, and 0.42 °C, respectively, according to a Bland-Altman analysis. Finally, the regression analysis revealed that there was a linear association between the axillary temperature and the forehead temperature, as well as the oral temperature and the forehead temperature due to the change in ambient temperature.

CONCLUSION

The changes in ambient temperature have a substantial impact on the temperature of the forehead. There are significant differences between the forehead and axillary temperatures, as well as the forehead and oral temperatures, when the ambient temperature is low. As the ambient temperature rises, the forehead temperature tends to progressively converge with the axillary and oral temperatures. In clinical or daily applications, it is not advised to utilize the forehead temperature derived from an uncorrected infrared thermometer as the foundation for a body temperature screening in public venues such as hospital outpatient clinics, shopping malls, airports, and train stations.

Optimal diagnostic fever thresholds using non-contact infrared thermometers under COVID-19

Fever screening is an effective method to detect infectors associated with different variants of coronavirus disease 2019 (COVID-19) based on the fact that most infectors with COVID-19 have fever symptoms. Non-contact infrared thermometers (NCITs) are widely used in fever screening. Nevertheless, authoritative data is lacking in defining "fever" at different body surface sites when using NCITs. The purpose of this study was to determine the optimal diagnostic threshold for fever screening using NICTs at different body surface sites, to improve the accuracy of fever screening and provide theoretical reference for healthcare policy. Participants (n = 1860) who were outpatients or emergency patients at Chengdu Women's and Children's Central Hospital were recruited for this prospective investigation from March 1 to June 30, 2021. NCITs and mercury axillary thermometers were used to measure neck, temple, forehead and wrist temperatures of all participants. Receiver operating characteristic curves were used to reflect the accuracy of NCITs. Linear correlation analysis was used to show the effect of age on body temperature. Multilinear regression analysis was used to explore the association between non-febrile participant's covariates and neck temperature. The mean age of participants was 3.45 ± 2.85 years for children and 28.56 ± 7.25 years for adults. In addition 1,304 (70.1%) participants were children (≤12), and 683 (36.7%) were male. The neck temperature exhibited the highest accuracy among the four sites. Further the optimal fever diagnostic thresholds of NCITs at the four body surface measurement sites were neck (36.75 °C, sensitivity: 0.993, specificity: 0.858); temple (36.55 °C, sensitivity: 0.974, specificity: 0.874); forehead (36.45 °C, sensitivity: 0.961, specificity: 0.813); and wrist (36.15 °C, sensitivity: 0.951, specificity: 0.434). Based on the findings of our study, we recommend 36.15, 36.45, 36.55, and 36.75 °C as the diagnostic thresholds of fever at the wrist, forehead, temple and neck, respectively. Among the four surface sites, neck temperature exhibited the highest accuracy.

May infrared thermometers hold the promise for effective early warnings for emerging respiratory infectious diseases? (Preprint)

BACKGROUND

Major respiratory infectious diseases, such as influenza, SARS-CoV, and SARS-CoV-2, have caused historic global pandemics with severe disease and economic burdens. Early warning and timely intervention are key to suppress such outbreaks.

OBJECTIVE

We propose a theoretical framework for a community-based early warning (EWS) system that will proactively detect temperature abnormalities in the community based on a collective network of infrared thermometer-enabled smartphone devices.

METHODS

We developed a framework for a community-based EWS and demonstrated its operation with a schematic flowchart. We emphasize the potential feasibility of the EWS and potential obstacles.

RESULTS

Overall, the framework uses advanced artificial intelligence (AI) technology on cloud computing platforms to identify the probability of an outbreak in a timely manner. It hinges on the detection of geospatial temperature abnormalities in the community based on mass data collection, cloud-based computing and analysis, decision-making, and feedback. The EWS may be feasible for implementation considering its public acceptance, technical practicality, and value for money. However, it is important that the proposed framework work in parallel or in combination with other early warning mechanisms due to a relatively long initial model training process.

CONCLUSIONS

The framework, if implemented, may provide an important tool for important decisions for early prevention and control of respiratory diseases for health stakeholders.

A Novel Non-Invasive Thermometer for Continuous Core Body Temperature: Comparison with Tympanic Temperature in an Acute Stroke Clinical Setting

There is a growing research interest in wireless non-invasive solutions for core temperature estimation and their application in clinical settings. This study aimed to investigate the use of a novel wireless non-invasive heat flux-based thermometer in acute stroke patients admitted to a stroke unit and compare the measurements with the currently used infrared (IR) tympanic temperature readings. The study encompassed 30 acute ischemic stroke patients who underwent continuous measurement (Tcore) with the novel wearable non-invasive CORE device. Paired measurements of Tcore and tympanic temperature (Ttym) by using a standard IR-device were performed 3−5 times/day, yielding a total of 305 measurements. The predicted core temperatures (Tcore) were significantly correlated with Ttym (r = 0.89, p < 0.001). The comparison of the Tcore and Ttym measurements by Bland−Altman analysis showed a good agreement between them, with a low mean difference of 0.11 ± 0.34 °C, and no proportional bias was observed (B = −0.003, p = 0.923). The Tcore measurements correctly predicted the presence or absence of Ttym hyperthermia or fever in 94.1% and 97.4% of cases, respectively. Temperature monitoring with a novel wireless non-invasive heat flux-based thermometer could be a reliable alternative to the Ttym method for assessing core temperature in acute ischemic stroke patients.

Remote investigation and assessment of vital signs (RIA-VS)-proof of concept for contactless estimation of blood pressure, pulse, respiratory rate, and oxygen saturation in patients with suspicion of COVID-19

BACKGROUND

Vital signs are critical in assessing the severity and prognosis of infections, for example, COVID-19, influenza, sepsis, and pneumonia. This study aimed to evaluate a new method for rapid camera-based non-contact measurement of heart rate, blood oxygen saturation, respiratory rate, and blood pressure.

METHODS

Consecutive adult patients attending a hospital emergency department for suspected COVID-19 infection were invited to participate. Vital signs measured with a new camera-based method were compared to the corresponding standard reference methods. The camera device observed the patient's face for 30 s from ∼1 m.

RESULTS

Between 1 April and 1 October 2020, 214 subjects were included in the trial, 131 female (61%) and 83 male (39%). The mean age was 44 years (range 18-81 years). The new camera-based device's vital signs measurements were, on average, very close to the gold standard but the random variation was larger than the reference methods.

CONCLUSIONS

The principle of contactless measurement of blood pressure, pulse, respiratory rate, and oxygen saturation works, which is very promising. However, technical improvements to the equipment used in this study to reduce its random variability is required before clinical implementation. This will likely be a game changer once this is sorted out.

CLINICAL TRIAL REGISTRATION

Universal Trial Number (UTN) U1111-1251-4114 and the ClinicalTrials.gov Identifier NCT04383457.

Temperature sensor based on an erbium-doped fiber Sagnac interferometer

The development of a highly sensitive all-fiber temperature sensor based on a Sagnac interferometer configuration is demonstrated here. We use 10 m of an erbium-doped fiber (EDF) as a passive sensing element inside the Sagnac loop, taking advantage of the extra birefringence added by the presence of the doping elements. Using a standard interrogation method of simply tracing a interference peak, we were able to detect temperature variations with a sensitivity of up to 0.2 nm/°C and high linearity. The results demonstrate, for the first time, that the usage of an EDF as a totally passive element can be an interesting option to extend the range of parameter possibilities achievable for highly sensitive temperature sensors.

Reliability of Non-Contact Infrared Thermometers for Fever Screening Under COVID-19

Purpose

Fever is one of the most typical clinical symptoms of coronavirus disease 2019 (COVID-19), and non-contact infrared thermometers (NCITs) are commonly used to screen for fever. However, there is a lack of authoritative data to define a “fever” when an NCIT is used and previous studies have shown that NCIT readings fluctuate widely depending on ambient temperatures and the body surface site screened. The aim of this study was to establish cut-off points for normal temperatures of different body sites (neck, forehead, temples, and wrist) and investigate the accuracy of NCITs at various ambient temperatures to improve the standardization and accuracy of fever screening.

Patients and Methods

A prospective investigation was conducted among 904 participants in the outpatient and emergency departments of Chengdu Women’s and Children’s Central Hospital. Body temperature was measured using NCITs and mercury axillary thermometers. A receiver operating characteristic curve was used to determine the accuracy of body temperature detection at the four body surface sites. Data on participant characteristics were also collected.

Results

Among the four surface sites, the neck temperature detection group had the highest accuracy. When the neck temperature was 37.35°C as the optimum fever diagnostic threshold, the sensitivity was 0.866. The optimum fever diagnostic thresholds for forehead, temporal, and wrist temperature were 36.65°C, 36.65°C, and 36.75°C, respectively. Moreover, triple neck temperature detection had the highest sensitivity, up to 0.998, whereas the sensitivity of triple wrist temperature detections was 0.949. Notably, the accuracy of NCITs significantly reduced when the temperature was lower than 18°C.

Conclusion

Neck temperature had the highest accuracy among the four NCIT temperature measurement sites, with an optimum fever diagnostic threshold of 37.35°C. Considering the findings reported in our study, we recommend triple neck temperature detection with NCITs as the fever screening standard for COVID-19.

Comparative Analysis of Human Body Temperatures Measured with Noncontact and Contact Thermometers

Body temperature measurement is one of the basic methods in clinical diagnosis. The problems of thermometry—interpretation of the accuracy and repeatability of various types of thermometers—are still being discussed, especially during the current pandemic in connection with the SARS-CoV-2 virus responsible for causing the COVID-19 disease. The aim of the study was to compare surface temperatures of the human body measured by various techniques, in particular a noncontact thermometer (infrared) and contact thermometers (mercury, mercury-free, electronic). The study included 102 randomly selected healthy women and men (age 18–79 years). The Bland–Altman method was used to estimate the 95% reproducibility coefficient, i.e., to assess the degree of conformity between different attempts. Temperatures measured with contact thermometers in the armpit are higher than temperatures measured without contact at the frontal area of the head. The methods used to measure with contact thermometers and a noncontact infrared thermometer statistically showed high measurement reliability. In order to correctly interpret the result of measuring human body temperature, it is necessary to indicate the place of measurement and the type of thermometer used.

Post-craniotomy fever and its associated factors in patients with traumatic brain injury

BACKGROUND

Fever frequently occurs in patients with traumatic brain injury and can cause secondary damage to the brain. Critical care nurses play essential roles in assessing and managing fever in these patients.

AIM

The study aimed to (a) examine the fever causes in and condition of neurosurgical patients with traumatic brain injury in intensive care, (b) identify the factors associated with fever, and (c) determine the effects of fever on hospital stay and prognosis.

STUDY DESIGN

This study is a retrospective observational design.

METHODS

Data were collected through chart reviews of 93 traumatic brain injury patients admitted to a teaching hospital's intensive care unit for postoperative care. Fever was defined as at least one episode of body temperature >38°C.

RESULTS

Of the 93 patients, 76 developed a fever within 1-week post-craniotomy. Of these, 49 were infection-related and 27 were unexplained. Results of logistic regression showed that the preoperative Glasgow coma scale score (ß = -.323; P = .013) and length of intubation (ß = .480; P = .005) were the key predictors of unexplained post-craniotomy fever, and these two variables (ß = -.494; P < .001 and ß = .479; P = .006, respectively) were also the key predictors of infection-related fever.

CONCLUSION

A significant portion of patients developed a fever during the first post-craniotomy week. Patients with a lower pre-craniotomy Glasgow coma scale score and a longer intubation length were at a greater risk for both infection-related fever and unexplained fever. Patients with fever had a bad outcome score.

RELEVANCE TO CLINICAL PRACTICE

Critical care nurses should closely monitor traumatic brain injury patients' body temperatures and employ evidence-based infection prevention and control measures to minimize their infection risks. Respiratory care and intensive care unit Liberation Bundle should be reinforced to liberate these patients from mechanical ventilation and its associated complications.

Threshold for defining fever varies with age, especially in children: A multi-site diagnostic accuracy study

Aim

The American Academy of Pediatrics and the European Centre for Pediatric and Adolescent Medicine guideline define fever as a temperature >38.0°C for all ages and recommend use of rectal thermometers in children <3 years. Based on new literature, this definition of fever using a fixed threshold of 38.0°C needs to be re‐examined.

Design

A multi‐site diagnostic accuracy study was conducted to compare an “age‐based” threshold model with a “fixed” threshold over 38.0°C on a total of 894 patients of which 373 were ill.

Methods

The “age‐based” and “fixed” threshold fever determinations were then compared to a clinical categorization (“well” or “ill”) conducted by a clinician through a comprehensive examination.

Results

The sensitivity and accuracy for the age‐based thresholds were found to be superior to the fixed thresholds in all ages and current ear thermometers were found equivalent to rectal thermometers in infants <6 months.