Temperature measurements in trauma patients: is the ear the key to the core?

Prehospital Active and Passive Warming in Trauma Patients

OBJECTIVE

Hypothermia is common among trauma patients and can lead to a serious rise in morbidity and mortality. This study was performed to investigate the effect of active and passive warming measures implemented in the prehospital phase on the body temperature of trauma patients.

METHODS

In a multicenter, multinational prospective observational design, the effect of active and passive warming measures on the incidence of hypothermia was investigated. Adult trauma patients who were transported by helicopter emergency medical services (HEMS) or ground emergency medical services with an HEMS physician directly from the scene of injury were included. Four HEMS/ground emergency medical services programs from Canada, the United States, and the Netherlands participated.

RESULTS

A total of 80 patients (n = 20 per site) were included. Eleven percent had hypothermia on presentation, and the initial evaluation occurred predominantly within 60 minutes after injury. In-line fluid warmers and blankets were the most frequently used active and passive warming measures, respectively. Independent risk factors for a negative change in body temperature were transportation by ground ambulance (odds ratio = 3.20; 95% confidence interval, 1.06-11.49; P = .03) and being wet on initial presentation (odds ratio = 3.64; 95% confidence interval, 0.99-13.36; P = .05).

CONCLUSION

For adult patients transported from the scene of injury to a trauma center, active and passive warming measures, most notably the removal of wet clothing, were associated with a favorable outcome, whereas wet patients and ground ambulance transport were associated with an unfavorable outcome with respect to temperature.

Measurement of exhaled breath temperature in patients under general anesthesia: A feasibility study

The aim of the present study was to investigate the respiratory parameters that influence the exhaled breath temperature (EBT) and the feasibility of using the latter to monitor the core temperature under general endotracheal anesthesia. A total of 20 patients undergoing abdominal surgery were included in the present study. At the first stage of the experiment, the respiratory rate was adjusted, while the other respiratory parameters [tidal volume, inspiratory and expiratory time ratio (TI:TE), and positive end expiratory pressure (PEEP)] were maintained at a constant level. At the second stage, the tidal volume was adjusted, while the other respiratory parameters were maintained at a constant level. At the third stage, the TI:TE was adjusted, while the other parameters were maintained at a constant level. At the fourth stage, PEEP was adjusted, while the other parameters were maintained at a constant level. In each experiment, the EBT, the maximum temperature of exhaled air in each min, the inhaled air temperature and the nasopharyngeal temperature (T nose) were recorded every min. During the first stage of the experiment, no significant difference was noted in the EBT at different levels of respiratory rate. During the second, third and fourth stage, no significant difference was noted in the EBT at different tidal volumes, TI:TE and PEEP, respectively. The EBT was significantly correlated with the T nose. Overall, the present study demonstrated that the EBT of patients undergoing abdominal surgery under general endotracheal anesthesia was not affected by the examined respiratory parameters and that it could be considered a feasible method of monitoring core temperature.

Prehospital body temperature measurement in trauma patients: A literature review

OBJECTIVES

Accidental hypothermia in trauma patients can contribute to cardiorespiratory dysfunction, acidosis, and coagulopathy, causing increased morbidity and mortality. The early recognition of the clinical signs of hypothermia and the accurate measurement of body temperature by prehospital care providers are essential to avoid deterioration. This review provides an overview of studies that examine the reliability of different core temperature measurement options, with a focus on the prehospital setting.

METHODS

A search was performed in PubMed, Embase, Cochrane Library, and CINAHL using combinations of the Medical Subject Headings terms "ambulances," "emergency medical services," "thermometers," "body temperature," "hypothermia," and "body temperature regulation." Studies up to October 2021 were included, and different measurement options were listed and discussed. Eligible studies included those that identified the specific type of thermometer and focused on the out-of-hospital environment.

RESULTS

The search strategy yielded 521 studies, five of which met the eligibility criteria. Four studies focused on tympanic temperature measurement, and one focused on temporal artery temperature measurement. Among the noninvasive options, tympanic temperature measurement was most frequently identified as a reliable option for out-of-hospital use.

CONCLUSION

A thermistor-based tympanic thermometer that features insulation of the ear and a temperature probe with a cap is likely the most suitable option for prehospital body temperature measurement in trauma patients. These results are based on outdated literature with currently more novel temperature measurement devices available. Future studies are necessary to provide strong recommendations regarding temperature measurement due to emerging technology, the lack of studies, and the heterogeneity of existing studies.

Discriminating Bacterial Infection from Other Causes of Fever Using Body Temperature Entropy Analysis

Body temperature is usually employed in clinical practice by strict binary thresholding, aiming to classify patients as having fever or not. In the last years, other approaches based on the continuous analysis of body temperature time series have emerged. These are not only based on absolute thresholds but also on patterns and temporal dynamics of these time series, thus providing promising tools for early diagnosis. The present study applies three time series entropy calculation methods (Slope Entropy, Approximate Entropy, and Sample Entropy) to body temperature records of patients with bacterial infections and other causes of fever in search of possible differences that could be exploited for automatic classification. In the comparative analysis, Slope Entropy proved to be a stable and robust method that could bring higher sensitivity to the realm of entropy tools applied in this context of clinical thermometry. This method was able to find statistically significant differences between the two classes analyzed in all experiments, with sensitivity and specificity above 70% in most cases.

Infrared Thermography in Wound Care, Surgery, and Sports Medicine: A Review

For many years, the role of thermometry was limited to systemic (core body temperature) measurements (e.g., pulmonary catheter) or its approximation using skin/mucosa (e.g., axillary, oral, or rectal) temperature measurements. With recent advances in material science and technology, thermal measurements went beyond core body temperature measurements and found their way in many medical specialties. The article consists of two primary parts. In the first part we overviewed current clinical thermal measurement technologies across two dimensions: (a) direct vs. indirect and (b) single-point vs. multiple-point temperature measurements. In the second part, we focus primarily on clinical applications in wound care, surgery, and sports medicine. The primary focus here is the thermographic imaging modality. However, other thermal modalities are included where relevant for these clinical applications. The literature review identified two primary use scenarios for thermographic imaging: inflammation-based and perfusion-based. These scenarios rely on local (topical) temperature measurements, which are different from systemic (core body temperature) measurements. Quantifying these types of diseases benefits from thermographic imaging of an area in contrast to single-point measurements. The wide adoption of the technology would be accelerated by larger studies supporting the clinical utility of thermography.

Core Temperature Measurement-Principles of Correct Measurement, Problems, and Complications

Core temperature reflects the temperature of the internal organs. Proper temperature measurement is essential to diagnose and treat temperature impairment in patients. However, an accurate approach has yet to be established. Depending on the method used, the obtained values may vary and differ from the actual core temperature. There is an ongoing debate regarding the most appropriate anatomical site for core temperature measurement. Although the measurement of body core temperature through a pulmonary artery catheter is commonly cited as the gold standard, the esophageal temperature measurement appears to be a reasonable and functional alternative in the clinical setting. This article provides an integrative review of invasive and noninvasive body temperature measurements and their relations to core temperature.

Hypothermia in Trauma

Hypothermia in trauma patients is a common condition. It is aggravated by traumatic hemorrhage, which leads to hypovolemic shock. This hypovolemic shock results in a lethal triad of hypothermia, coagulopathy, and acidosis, leading to ongoing bleeding. Additionally, hypothermia in trauma patients can deepen through environmental exposure on the scene or during transport and medical procedures such as infusions and airway management. This vicious circle has a detrimental effect on the outcome of major trauma patients. This narrative review describes the main factors to consider in the co-existing condition of trauma and hypothermia from a prehospital and emergency medical perspective. Early prehospital recognition and staging of hypothermia are crucial to triage to proper care to improve survival. Treatment of hypothermia should start in an early stage, especially the prevention of further cooling in the prehospital setting and during the primary assessment. On the one hand, active rewarming is the treatment of choice of hypothermia-induced coagulation disorder in trauma patients; on the other hand, accidental or clinically induced hypothermia might improve outcomes by protecting against the effects of hypoperfusion and hypoxic injury in selected cases such as patients suffering from traumatic brain injury (TBI) or traumatic cardiac arrest.

Insight into the use of tympanic temperature during target temperature management in emergency and critical care: a scoping review

BACKGROUND

Target temperature management (TTM) is suggested to reduce brain damage in the presence of global or local ischemia. Prompt TTM application may help to improve outcomes, but it is often hindered by technical problems, mainly related to the portability of cooling devices and temperature monitoring systems. Tympanic temperature (TTy) measurement may represent a practical, non-invasive approach for core temperature monitoring in emergency settings, but its accuracy under different TTM protocols is poorly characterized. The present scoping review aimed to collect the available evidence about TTy monitoring in TTM to describe the technique diffusion in various TTM contexts and its accuracy in comparison with other body sites under different cooling protocols and clinical conditions.

METHODS

The scoping review was conducted following the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis extension for scoping reviews (PRISMA-ScR). PubMed, Scopus, and Web of Science electronic databases were systematically searched to identify studies conducted in the last 20 years, where TTy was measured in TTM context with specific focus on pre-hospital or in-hospital emergency settings.

RESULTS

The systematic search identified 35 studies, 12 performing TTy measurements during TTM in healthy subjects, 17 in patients with acute cardiovascular events, and 6 in patients with acute neurological diseases. The studies showed that TTy was able to track temperature changes induced by either local or whole-body cooling approaches in both pre-hospital and in-hospital settings. Direct comparisons to other core temperature measurements from other body sites were available in 22 studies, which showed a faster and larger change of TTy upon TTM compared to other core temperature measurements. Direct brain temperature measurements were available only in 3 studies and showed a good correlation between TTy and brain temperature, although TTy displayed a tendency to overestimate cooling effects compared to brain temperature.

CONCLUSIONS

TTy was capable to track temperature changes under a variety of TTM protocols and clinical conditions in both pre-hospital and in-hospital settings. Due to the heterogeneity and paucity of comparative temperature data, future studies are needed to fully elucidate the advantages of TTy in emergency settings and its capability to track brain temperature.

Comparison of Endoscopic and Ultrasonographic Measurements of the Subglottic Airway in Children

OBJECTIVE

To compare measurements of the pediatric subglottis obtained by surgeon-performed ultrasound and endoscopy.

STUDY DESIGN

Prospective observational comparison-of-methods study.

SETTING

Tertiary care pediatric hospital.

SUBJECTS AND METHODS

Thirty-one patients who underwent direct laryngoscopy from May 2017 to July 2018 were recruited. Transcervical ultrasound was used to visualize the vocal folds, subglottis, and cervical trachea. The anterior-posterior (AP) and transverse (TV) diameter of the subglottic space were measured endoscopically and via ultrasound by 2 independent evaluators. Measurements were compared for correlation, bias, and agreement. A clinically acceptable bias for subglottic diameter was assumed to be 0.5 mm or less.

RESULTS

The median age of enrolled patients was 2.6 years (range, 4 months-13.3 years). Endoscopic subglottic AP and TV measurements ranged from 3.33 mm to 14.81 mm and from 4.44 mm to 11.65 mm, respectively, while ultrasonographic AP and TV measurements ranged from 4.57 mm to 9.85 mm and from 3.77 mm to 8.96 mm. Pearson coefficient showed strong a correlation for both endoscopic and ultrasound AP (R = 0.8081, P < .0001) and TV (R = 0.8796, P < .001) measurements of the subglottis. Bland-Altman plots revealed a bias (average discrepancy) for AP measurements of 0.22 mm and 0.11 mm for TV measurements.

CONCLUSION

Endoscopic and ultrasonography measurements of the pediatric subglottic airway were strongly correlated. The discrepancy between AP and TV measurements was less than 0.5 mm. Ultrasound of the subglottis may be an alternative to endoscopic assessment of the airway for measurement of the subglottic airway in children in select cases.

Body temperature measurement in ambulance: a challenge of 21-st century?

Background

Some crucial decisions in treatment of hypothermic patients are closely linked to core body temperature. They concern modification of resuscitation algorithms and choosing the target hospital. Under- as well as over-estimation of a patient’s temperature may limit his chances for survival. Only thermometers designed for core temperature measurement can serve as a guide in such decision making. The aim of the study was to assess whether ambulance teams are equipped properly to measure core temperature.

Methods

A survey study was conducted in collaboration with the Health Ministry in April 2018. Questionnaires regarding the model, number, and year of production of thermometers were sent to each pre-hospital unit of the National Emergency Medical System in Poland.

Results

A total of 1523 ground ambulances are equipped with 1582 thermometers. 53.57% are infrared-based ear thermometers, 23.02% are infrared-based surface thermometers, and 20.13% are conventional medical thermometers. Only 3.28% of devices are able to measure core body temperature. Most of analyzed thermometers (91.4%) are not allowed to operate in ambient temperature below 10 °C.

Conclusions

There are only 3.28% of ground ambulances that are able to follow precisely international guidelines regarding a patient’s core body temperature. A light, reliable thermometer designed to measure core temperature in pre-hospital conditions is needed.

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

Extensive research has been devoted to developing methods for assessing core body temperature, and to determine which method is most accurate. A number of wireless dermal thermometers for home use are presently available, but their relation to core body temperature and suitability for use in clinical research has hitherto not been assessed. The current study aimed to evaluate such thermometers by comparing them to the results of a rectal thermometer. Four wireless dermal thermometers for home use (FeverSmart, iThermonitor, Quest Temp Sitter, and Thermochron iButton) were applied to 15 patients during 24 h, and rectal temperature was measured at four occasions. Pearson correlation revealed moderate correlation for the Feversmart (r = 0.75), iThermonitor (r = 0.79), and Thermochron iButton (r = 0.71) systems. The Quest Temp Sitter system malfunctioned repeatedly, and the correlation (r = 0.29) for this method should therefore be assessed with caution. All dermal thermometers rendered lower average temperatures than Terumo c405 (Feversmart -0.70 ± 0.65 °C; iThermonitor -0.77 ± 0.53 °C, Quest Temp Sitter -1.18 ± 0.66 °C, and Thermochron iButton -0.87 ± 0.65 °C). Sensitivity of the dermal thermometers for detecting core temperatures ≥38.0 °C was low, ranging from 0.33 to 0.6, but improved to 0.60 to 0.80 after adjusting temperatures by the methods' average deviation from rectal temperature. The results from the dermal thermometers tested here showed an insufficient correlation to core temperature to be used for core temperature monitoring in clinical research and practice. Unfortunately, other options for non-invasive temperature measurements are few. The two thermometers with the least unsatisfactory performance profile in our evaluations were the Feversmart and iThermonitor systems.

When do trauma patients lose temperature? - a prospective observational study

BACKGROUND

The prevalence of hypothermia in trauma patients is high and rapid recognition is important to prevent further heat loss. Hypothermia is associated with poor patient outcomes and is an independent predictor of increased mortality. The aim of this study was to analyze the changes in core body temperature of trauma patients during different treatment phases in the pre-hospital and early in-hospital settings.

METHODS

A prospective observational cohort study in severely injured patients. Continuous core temperature monitoring using an epitympanic sensor in the auditory canal was initiated at the scene of injury and continued for 3 h. The degree of patient insulation was photo-documented throughout, and graded on a binary scale. The outcome variable was temperature change in each treatment phase.

RESULTS

Twenty-two patients were included with a median injury severity score (ISS) of 21 (IQR 14-29). Most patients (N = 16, 73%) were already hypothermic (< 36°C) on scene at their first measurement. Twenty patients (91%) became colder at the scene of injury; on average, the decline was -1.7°C/h. Full clothing reduced this value to -1.1°C/h. Temperature remained essentially stable during ambulance and emergency department phases.

CONCLUSION

Trauma patients are at risk for hypothermia already at the scene of injury. Lay persons and professionals should focus on early prevention of heat loss. An active, individually tailored approach to counter hypothermia in trauma should begin immediately at the scene of injury and continue during transportation to hospital. Active rewarming during evacuation should be considered.

A smart all-in-one device to measure vital signs in admitted patients

Background

Vital sign measurements in hospitalized patients by nurses are time consuming and prone to operational errors. The Checkme, a smart all-in-one device capable of measuring vital signs, could improve daily patient monitoring by reducing measurement time, inter-observer variability, and incorrect inputs in the Electronic Health Record (EHR). We evaluated the accuracy of self measurements by patient using the Checkme in comparison with gold standard and nurse measurements.

Methods and findings

This prospective comparative study was conducted at the Internal Medicine ward of an academic hospital in the Netherlands. Fifty non-critically ill patients were enrolled in the study. Time-related measurement sessions were conducted on consecutive patients in a randomized order: vital sign measurement in duplicate by a well-trained investigator (gold standard), a Checkme measurement by the patient, and a routine vital sign measurement by a nurse. In 41 patients (82%), initial calibration of the Checkme was successful and results were eligible for analysis. In total, 69 sessions were conducted for these 41 patients. The temperature results recorded by the patient with the Checkme differed significantly from the gold standard core temperature measurements (mean difference 0.1 ± 0.3). Obtained differences in vital signs and calculated Modified Early Warning Score (MEWS) were small and were in range with predefined accepted discrepancies.

Conclusions

Patient-calculated MEWS using the Checkme, nurse measurements, and gold standard measurements all correlated well, and the small differences observed between modalities would not have affected clinical decision making. Using the Checkme, patients in a general medical ward setting are able to measure their own vital signs easily and accurately by themselves. This could be time saving for nurses and prevent errors due to manually entering data in the EHR.

The use of non-invasive thermometers in healthcare facilities: a scoping review protocol

REVIEW OBJECTIVE AND QUESTIONS

The objective of the review is to map the available evidence to provide an overview of the use of non-invasive thermometers in the general context of health care. The specific questions, in regards to the available international published and unpublished literature, are.