ACSM Expert Consensus Statement on Exertional Heat Illness: Recognition, Management, and Return to Activity.

ABSTRACT: Exertional heat stroke (EHS) is a true medical emergency with potential for organ injury and death. This consensus statement emphasizes that optimal exertional heat illness management is promoted by a synchronized chain of survival that promotes rapid recognition and management, as well as communication between care teams. Health care providers should be confident in the definitions, etiologies, and nuances of exertional heat exhaustion, exertional heat injury, and EHS. Identifying the athlete with suspected EHS early in the course, stopping activity (body heat generation), and providing rapid total body cooling are essential for survival, and like any critical life-threatening situation (cardiac arrest, brain stroke, sepsis), time is tissue. Recovery from EHS is variable, and outcomes are likely related to the duration of severe hyperthermia. Most exertional heat illnesses can be prevented with the recognition and modification of well-described risk factors ideally addressed through leadership, policy, and on-site health care.

Self-monitored and optically powered fiber-optic device for localized hyperthermia and controlled cell death in vitro.

Localized hyperthermia therapy involves heating a small volume of tissue in order to kill cancerous cells selectively and with limited damage to healthy cells and surrounding tissue. However, these features are only achievable through real-time control of the tissue temperature and heated volume, both of which are difficult to obtain with current heating systems and techniques. This work introduces an optical fiber-based active heater that acts both as a miniature heat source and as a thermometer. The heat-induced damage in the tissue is caused by the conductive heat transfer from the surface of the device, while the heat is generated in an absorptive coating on the fiber by near-infrared light redirected from the fiber core to the surface by a tilted fiber Bragg grating inscribed in the fiber core. Simultaneous monitoring of the reflection spectrum of the grating provides a measure of the local temperature. Localized temperature increases between 0°C and 100°C in 10 mm-long/5 mm-diameter cylindrical volumes are obtained with continuous-wave pump power levels up to 1.8 W. Computational and experimental results further indicate that the temperature rise and dimensions of the heated volume can be maintained at a nearly stable level determined by the input optical power.

Comparison of rectal and axillary temperature measurements in preterm newborns.

OBJECTIVE: To compare rectal and axillary temperatures in preterm newborns on admission to the neonatal intensive care unit (NICU). DESIGN: Secondary analysis of data collected in a randomised controlled trial (RCT). SETTING: Maternity hospital, level 3 NICU. PATIENTS: Seventy-two newborns <31 weeks who were enrolled in the BAMBINO RCT (A randomised trial of exothermic mattresses to prevent heat loss in preterm infants at birth, ISRCTN31707342). INTERVENTIONS: Newborns were placed in polyethylene bags and were randomised to placement on exothermic mattresses, or not in the delivery room. All infants had rectal and axillary temperatures measured in immediate succession using a digital thermometer on NICU admission. OUTCOME MEASURES: Admission rectal and axillary temperatures. RESULTS: Mean (SD) gestational age was 28 (2) weeks and birth weight was 1138 (374) g. Mean rectal-axillary temperature difference was 0.1 (0.5°C) (range -1.4°C to +1.5°C). Rectal and axillary temperatures differed by ≥0.5°C in 18/72 (25%) infants; axillary temperature was higher than rectal in 6 (8%) and lower in 12 (17%). There was a positive linear relationship between rectal and axillary measurements (Pearson's correlation R=0.84). Applying the Bland-Altman technique, the width of 95% prediction interval was 1.8°C (-0.8°C to 1.0°C) implying that rectal and axillary measurements may vary by up to 1.0°C. Axillary temperature had a sensitivity of 65% when used to detect rectal hyperthermia and 100% sensitivity for hypothermia. CONCLUSION: Paired rectal and axillary temperature measurements in preterm newborns on NICU admission vary significantly. Axillary temperature was sensitive at detecting rectal hypothermia but not hyperthermia. Axillary temperature may not be an accurate proxy for rectal temperature measurement in all preterm newborns on NICU admission.

Death following extreme temperature exposure: Histological, biochemical and immunohistochemical markers.

INTRODUCTION: Defining extreme temperatures as the cause of death remains challenging. It is mostly based on circumstantial, macroscopic and microscopic features. METHODS: We retrospectively compared groups of cases of fatal hypothermia, fatal hyperthermia and non-extreme temperature-related deaths. We analysed specific histological findings, focusing on samples from the liver, pancreas and kidney. RESULTS: Between 1 January 2013 and 31 December 2016, 15 autopsies were performed for deaths related to extreme temperatures. They included 11 cases of fatal hypothermia (group A), four cases of fatal hyperthermia (group B) and eight controls (group C). Perinuclear hepatocyte vacuolisation was observed in seven cases of hypothermia, one case of hyperthermia and four controls. Pancreatic cytoarchitecture was well preserved in two cases of hypothermia, one case of hyperthermia and two controls. No particular microscopic feature was found in pancreatic samples. Renal epithelial tubular cell vacuolisation was observed in seven cases of hypothermia and one case of hyperthermia, while it was absent in all controls. Chromogranin A (CgA) was markedly positive in the pancreatic tissue of five cases of fatal hypothermia and one control, and mildly positive in one case of fatal hyperthermia. No significant p-values were observed for any comparisons (p > 0.05), except when hypothermia cases group were compared to the control group for the Armanni-Ebstein phenomenon test (p = 0.0078). CONCLUSIONS: Although our study did not find a specific microscopic marker, hepatocyte vacuolisation, the Armanni-Ebstein phenomenon and pancreatic CgA positivity, taken together, may be useful tools to confirm hypo- and hyperthermia-related deaths, in addition to circumstantial and macroscopic findings.

Postembolization syndrome in endovascular interventions on the gonadal veins.

OBJECTIVE: The present study evaluated the incidence of postembolization syndrome (PES) after endovascular coil embolization of the gonadal veins (EEGV) in patients with pelvic congestion syndrome and investigated the appropriate medical treatment. METHODS: EEGV was performed in 70 female patients with pelvic congestion syndrome (left-sided in 58, right-sided in 3, and bilateral in 9 patients). For embolization, 0.035-in. coils with an 8- to 12-mm diameter and 10- to 20-cm length were used. Assessments of the EEGV results and possible PES symptoms were performed on days 1, 5, 10, 20, and 30 after the procedure and included transvaginal and transabdominal duplex ultrasound scanning of the pelvic veins and at the embolization site. RESULTS: PES had manifested with increased pelvic pain, tenderness along the embolized vein, and hyperthermia ≤37.5°C to 37.8°C and had developed in 14 patients (20%). For PES treatment, a nonsteroidal anti-inflammatory drug (diclofenac, 75 mg daily for 3-7 days; mean, 4.2 ± 1.1 days) and a venoactive drug (micronized purified flavonoid fraction, 1000 mg daily for 2 months) were used. Medical treatment was associated with a significant reduction in PES symptoms in all patients within 14 days and complete resolution by day 30 after embolization. duplex ultrasound scanning revealed thrombosis of parametrial veins in 12 of 56 patients (21.4%) with successful EEGV and 3 of 14 patients (21.4%) with PES. CONCLUSIONS: In patients who have undergone EEGV, increased pelvic pain, the occurrence of tenderness along the embolized vein, and the presence of hyperthermia should be considered as PES manifestations. In our study, PES occurred in 20% of the treated patients.

Methods to quantify heat stress in ruminants: Current status and future prospects.

The physiology of hyperthermia or heat stress in mammals is complex. It is a totally systemic condition that in varying degrees involves all organs, tissues and body fluid compartments. The nature and magnitude of the response is influenced by animal specific characteristics (e.g. age, diet, body condition, gender, reproductive stage), environment and animal management. Given the multifaceted nature of heat stress, and the varied ruminant production systems based in varied geoclimatic zones, it has been difficult to find appropriate measures of heat stress for production ruminants. This has become an urgent challenge as production systems intensify globally in a warming climate. Bioclimatic indices such as the Temperature-Humidity Index (THI) have evolved to incorporate some measure of animal physiology. However, these indices do not have strong relationships with core temperature trajectories and altered respiratory dynamics of animals with excessive heat load. In recent decades, the careful physiology studies of the 1950-80s, have given way to numerous studies trialling a plethora of new technologies and computational approached to measure heat stress. Infrared thermography of body surface temperatures, automated measures of respiration rate and radiotelemetry of internal body temperatures are the most intensively researched. The common goal has been to find the 'holy grail' decision-making threshold or timepoint as to the animal's wellbeing. Are we making any progress?

Epidural analgesia, intrapartum hyperthermia, and neonatal brain injury: a systematic review and meta-analysis.

BACKGROUND: Epidural analgesia is associated with intrapartum hyperthermia, and chorioamnionitis is associated with neonatal brain injury. However, it is not known if epidural hyperthermia is associated with neonatal brain injury. This systematic review and meta-analysis investigated three questions: (1) does epidural analgesia cause intrapartum hyperthermia, (2) is intrapartum hyperthermia associated with neonatal brain injury, and (3) is epidural-induced hyperthermia associated with neonatal brain injury? METHODS: PubMed, ISI Web of Knowledge, The Cochrane Library, and Embase were searched from inception to January 2020 using Medical Subject Headings (MeSH) terms relating to epidural analgesia, hyperthermia, labour, and neonatal brain injury. Studies were reviewed independently for inclusion and quality by two authors (Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach). Two meta-analyses were performed using the Mantel-Haenszel fixed effect method to generate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Forty-one studies were included for Question 1 (646 296 participants), 36 for Question 2 (11 866 021 participants), and two studies for Question 3 (297 113 participants). When the mode of analgesia was randomised, epidural analgesia was associated with intrapartum hyperthermia (OR: 4.21; 95% CI: 3.48-5.09). There was an association between intrapartum hyperthermia and neonatal brain injury (OR: 2.79; 95% CI: 2.54-2.3.06). It was not possible to quantify the association between epidural-induced hyperthermia and neonatal brain injury. CONCLUSIONS: Epidural analgesia is a cause of intrapartum hyperthermia, and intrapartum hyperthermia of any cause is associated with neonatal brain injury. Further work is required to establish if epidural-induced hyperthermia is a cause of neonatal brain injury.

Impact of temperature change from admission to day one on neonatal mortality in a low-resource setting.

BACKGROUND: Thermal control after birth is an essential part of neonatal care. However, the relationship between neonatal temperature at and after admission is unknown. This study aimed to evaluate the change between neonatal temperature at admission and at day 1, and its impact on mortality. METHODS: Retrospective observational study at the Beira Central Hospital, Mozambique. Axillary temperatures were recorded at admission and at day 1 in 1,226 neonates who were admitted to the Special Care Unit between January 1 and December 31, 2017. The relationship between mortality rate and temperature change was evaluated with a matrix plot and a forest plot (obtained from a logistic regression model as odds ratios with 95% confidence intervals). RESULTS: Normothermia was found in 415 neonates (33.8%) at admission and in 638 neonates (52.0%) at day 1. Mortality rate was highest in (i) neonates who remained in severe/moderate hypothermia (74%), (ii) neonates who rewarmed from hypothermia (40-55%), and (iii) neonates who chilled to severe/moderate hypothermia (38-43%). Multivariable analysis confirmed that temperature change from admission to day 1 was an independent predictor of mortality (p < 0.0001). CONCLUSIONS: In a low-resource setting, one out of three neonates was found hypothermic at day 1 irrespectively of admission temperature. Relevant thermal deviations occurred in a high proportion of newborns with normothermia at admission. Being cold at admission and becoming cold or hyperthermic at day 1 were associated with increased likelihood of mortality. Appropriate actions to prevent both hypothermia and hyperthermia represent both a challenge and a priority during postnatal period.