Evaluation of commercial, wireless dermal thermometers for surrogate measurements of core temperature

Free-living core body temperature monitoring using a wrist-worn sensor after COVID-19 booster vaccination: a pilot study

Core body temperature (CBT) is a key vital sign and fever is an important indicator of disease. In the past decade, there has been growing interest for vital sign monitoring technology that may be embedded in wearable devices, and the COVID-19 pandemic has highlighted the need for remote patient monitoring systems. While wrist-worn sensors allow continuous assessment of heart rate and oxygen saturation, reliable measurement of CBT at the wrist remains challenging. In this study, CBT was measured continuously in a free-living setting using a novel technology worn at the wrist and compared to reference core body temperature measurements, i.e., CBT values acquired with an ingestible temperature-sensing pill. Fifty individuals who received the COVID-19 booster vaccination were included. The datasets of 33 individuals were used to develop the CBT prediction algorithm, and the algorithm was then validated on the datasets of 17 participants. Mean observation time was 26.4 h and CBT > 38.0 °C occurred in 66% of the participants. CBT predicted by the wrist-worn sensor showed good correlation to the reference CBT (r = 0.72). Bland-Altman statistics showed an average bias of 0.11 °C of CBT predicted by the wrist-worn device compared to reference CBT, and limits of agreement were - 0.67 to + 0.93 °C, which is comparable to the bias and limits of agreement of commonly used tympanic membrane thermometers. The small size of the components needed for this technology would allow its integration into a variety of wearable monitoring systems assessing other vital signs and at the same time allowing maximal freedom of movement to the user.

The Accuracy of a Wireless Axillary Thermometer for Core Temperature Monitoring in Pediatric Patients Having Noncardiac Surgery: An Observational Study

PURPOSE

A wireless and wearable axillary thermometer (iThermonitor) has been validated for perioperative core temperature monitoring in adults. The purpose of this study was to evaluate its accuracy in pediatrics having non-cardiac surgery.

DESIGN

Prospective observational study.

METHODS

From January 2019 to December 2019, 70 children aged younger than 14 years undergoing surgery in a tertiary hospital were selected. Pairs of esophageal temperatures (T_Eso), rectal temperatures (T_Rec), and axillary temperatures monitored by the iThermonitor (T_iTh) were collected every 5 min during surgery. Taking T_Eso as reference, the bias between T_Eso and T_iTh and the proportion of bias within ±0.5°C were calculated. Bland-Altman method was used to analyze the 95% of limits of agreement (LOA) between T_iTh and T_Eso. The same analyses were done for T_Rec. FINDINGS: A total of 2232 pairs of temperatures were collected. The bias (mean ± SD) between T_iTh and T_Eso was -0.07 °C ± 0.25°C, and 95% LOA was -0.07°C ± 0.50°C. The proportion of bias within ±0.5°C accounted for 96% (95% Confidence Interval [CI], 92-98%). Higher bias and 95% LOA, and lower proportion of bias within ± 0.5°C were found between T_Rec and T_Eso than those between T_iTh and T_Eso.

CONCLUSION

During pediatric non-cardiac surgery, axillary temperature derived from iThermonitor is in good agreement with esophageal temperature and can be used as an alternative to core temperature.

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

Not much is known about how accurate and reproducible different thermometers are at diagnosing patients with suspected fever. The study aims at evaluating which peripheral thermometers are more accurate and reproducible. We searched Medline, Embase, Scopus, WOS, CENTRAL, and Cinahl to perform: (1) diagnostic accuracy meta-analysis (MA) using rectal mercury-in-glass or digital thermometry as reference, and bivariate models for pooling; (2) network MA to estimate differences in mean temperature between devices; (3) Bland-Altman method to estimate 95% coefficient of reproducibility. PROSPERO registration: CRD42020174996. We included 46 studies enrolling more than 12,000 patients. Using 38 °C (100.4 ℉) as cut-off temperature, temporal infrared thermometry had a sensitivity of 0.76 (95% confidence interval, 0.65, 0.84; low certainty) and specificity of 0.96 (0.92, 0.98; moderate certainty); tympanic infrared thermometry had a sensitivity of 0.77 (0.60,  0.88; low certainty) and specificity of 0.98 (0.95, 0.99; moderate certainty). For all the other index devices, it was not possible to pool the estimates. Compared to the rectal mercury-in-glass thermometer, mean temperature differences were not statistically different from zero for temporal or tympanic infrared thermometry; the median coefficient of reproducibility ranged between 0.53 °C [0.95 ℉] for infrared temporal and 1.2 °C [2.16 ℉] for axillary digital thermometry. Several peripheral thermometers proved specific, but not sensitive for diagnosing fever with rectal thermometry as a reference standard, meaning that finding a temperature below 38 °C does not rule out fever. Fixed differences between temperatures together with random error means facing differences between measurements in the order of 2 °C [4.5 ℉]. This study informs practitioners of the limitations associated with different thermometers; peripheral ones are specific but not sensitive.

Review of the efficacy of infrared thermography for screening infectious diseases with applications to COVID-19

Purpose: The recent coronavirus disease 2019 (COVID-19) pandemic, which spread across the globe in a very short period of time, revealed that the transmission control of disease is a crucial step to prevent an outbreak and effective screening for viral infectious diseases is necessary. Since the severe acute respiratory syndrome (SARS) outbreak in 2003, infrared thermography (IRT) has been considered a gold standard method for screening febrile individuals at the time of pandemics. The objective of this review is to evaluate the efficacy of IRT for screening infectious diseases with specific applications to COVID-19. Approach: A literature review was performed in Google Scholar, PubMed, and ScienceDirect to search for studies evaluating IRT screening from 2002 to present using relevant keywords. Additional literature searches were done to evaluate IRT in comparison to traditional core body temperature measurements and assess the benefits of measuring additional vital signs for infectious disease screening. Results: Studies have reported on the unreliability of IRT due to poor sensitivity and specificity in detecting true core body temperature and its inability to identify asymptomatic carriers. Airport mass screening using IRT was conducted during occurrences of SARS, Dengue, Swine Flu, and Ebola with reported sensitivities as low as zero. Other studies reported that screening other vital signs such as heart and respiratory rates can lead to more robust methods for early infection detection. Conclusions: Studies evaluating IRT showed varied results in its efficacy for screening infectious diseases. This suggests the need to assess additional physiological parameters to increase the sensitivity and specificity of non-invasive biosensors.

Evaluation of a wearable wireless device with artificial intelligence, iThermonitor WT705, for continuous temperature monitoring for patients in surgical wards: a prospective comparative study

OBJECTIVES

To evaluate a new-generation, non-invasive, wireless axillary thermometer with artificial intelligence, iThermonitor (WT705, Raiing Medical, Beijing, China), and to ascertain its feasibility for perioperative continuous body temperature monitoring in surgical patients.

SETTING

Departments of Biliary Surgery and Operating Room and the post-anaesthesia care unit of a university teaching hospital in Chengdu, China.

PARTICIPANTS

A total of 526 adult surgical patients were consecutively enrolled.

DESIGN

This was a prospective observational study. Axillary temperatures were continuously recorded with iThermonitor throughout the whole perioperative period. The temperatures of the contralateral armpit were measured with mercury thermometers at 8:00, 12:00, 16:00 and 20:00 every day and were used as references.

OUTCOME MEASURES

The outcomes were the accuracy and precision of the temperatures measured with iThermonitor, the validity to detect fever and the feasibility of continuous wear. Pairs of temperatures were evaluated with Student's t-test, Pearson's correlation and repeated-measures Bland-Altman plot.

RESULTS

A total of 3621 pairs of body temperatures were obtained. The temperatures measured with iThermonitor agreed with those measured with the mercury thermometers overall, with a mean difference of 0.03°C±0.35°C and a moderate correlation (r=0.755, p<0.001). The 95% limits of agreement (LoA) ranged from -0.63°C to 0.73°C, with 5.11% of the differences outside the 95% LoA. The intraclass correlation coefficient was 0.753. Continuous temperature monitoring captured more fevers than intermittent observation (117/526 vs 91/526, p<0.001), detected fever up to 4.35 hours earlier, and captured a higher peak temperature (0.29°C±0.27°C, 95% CI: 0.26-0.31). All subjects felt that wearing iThermonitor was more or less comfortable and did not affect their daily activities.

CONCLUSIONS

iThermonitor is promising for continuous remote temperature monitoring in surgical patients. However, further developments are still needed to improve the precision of this device, especially for temperature detection in underweight patients and those with lower body temperature.

TRIAL REGISTRATION NUMBER

ChiCTR1900024549; Results (registered on 5 July 2019).

Understanding the reactogenicity of 4CMenB vaccine: Comparison of a novel and conventional method of assessing post-immunisation fever and correlation with pre-release in vitro pyrogen testing

BACKGROUND

Better understanding of vaccine reactogenicity is crucial given its potential impact upon vaccine safety and acceptance. Here we report a comparison between conventional and novel (continuous) methods of monitoring temperature and evaluate any association between reactogenicity and the monocyte activation test (MAT) employed for testing four-component capsular group B meningococcal vaccine (4CMenB) batches prior to release for clinical use in Europe.

METHODS

Healthy 7-12-week-old infants were randomised in two groups: group PCV13 2 + 1 (received pneumococcal conjugate vaccine 13 valent (PCV13) at 2, 4 and 12 months) and group PCV13 1 + 1 (received reduced schedule at 3 and 12 months). In both, infants received the remaining immunisations as per UK national schedule (including 4CMenB at 2, 4 and 12 months of age). Fever was measured for the first 24 h after immunisations using an axillary thermometer and with a wireless continuous temperature monitoring device (iButton®). To measure the relative pyrogenicity of individual 4CMenB batches, MAT was performed according to Ph. Eu. chapter 2.6.30 method C using PBMCs with IL-6 readout.

RESULTS

Fever rates detected by the iButton® ranged from 28.7% to 76.5% and from 46.6% to 71.1% in group PCV13 2 + 1 and PCV13 1 + 1 respectively, across all study visits. The iButton® recorded a higher number of fever episodes when compared with axillary measurements in both groups (range of axillary temperature fevers; group PCV13 2 + 1: 6.7%-38%; group PCV13 1 + 1: 11.4%-37.1%). An agreement between the two methods was between 0.39 and 0.36 (p < 0.001) at 8 h' time-point post primary immunisations. No correlation was found between MAT scores and fever rates, or other reported adverse events.

CONCLUSIONS

It is likely that conventional, intermittent, fever measurements underestimates fever rates following immunisation. 4CMenB MAT scores didn't predict reactogenicity, providing reassurance that vaccine batches with the highest acceptable pyrogen level are not associated with an increase in adverse events. Clinicaltrials.gov identifier: NCT02482636.

Exercise capacity and body mass index - important predictors of change in resting heart rate

BACKGROUND

Resting heart rate (RHR) is an obtainable, inexpensive, non-invasive test, readily available on any medical document. RHR has been established as a risk factor for cardiovascular morbidity, is related to other cardiovascular risk factors, and may possibly predict them. Change in RHR over time (∆RHR) has been found to be a potential predictor of mortality.

METHODS

In this prospective study, RHR and ∆RHR were evaluated at baseline and over a period of 2.9 years during routine check-ups in 6683 subjects without known cardiovascular disease from the TAMCIS: Tel-Aviv Medical Center Inflammation Survey. Multiple linear regression analysis with three models was used to examine ∆RHR. The first model accounted for possible confounders by adjusting for age, sex and body mass index (BMI). The 2nd model included smoking status, baseline RHR, diastolic blood pressure (BP), dyslipidemia, high-density lipoprotein (HDL) and metabolic equivalents of task (MET), and in the last model the change in MET and change in BMI were added.

RESULTS

RHR decreased with age, even after adjustment for sex, BMI and MET. The mean change in RHR was - 1.1 beats/min between two consecutive visits, in both men and women. This ∆RHR was strongly correlated with baseline RHR, age, initial MET, and change occurring in MET and BMI (P < 0.001).

CONCLUSIONS

Our results highlight the need for examining individual patients' ∆RHR. Reinforcing that a positive ∆RHR is an indicator of poor adherence to a healthy lifestyle.