Induction of therapeutic hypothermia requires modulation of thermoregulatory defenses

Protection of Workers Exposed to Radiofrequency Electromagnetic Fields: A Perspective on Open Questions in the Context of the New ICNIRP 2020 Guidelines

Workers in occupational settings are usually exposed to numerous sources of electromagnetic fields (EMF) and to different physical agents. Risk assessment for industrial workplaces concerning EMF is not only relevant to operators of devices or machinery emitting EMF, but also to support-workers, bystanders, service and maintenance personnel, and even visitors. Radiofrequency EMF guidelines published in 2020 by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) may also be indirectly applied to assess risks emerging from EMF sources at workplaces by technical standards or legislation. To review the applicability and adequacy to assess exposure to EMF in occupational settings in the European Union, the most current ICNIRP guidelines on radiofrequency EMF are reviewed. Relevant ICNIRP fundamentals and principles are introduced, followed by practical aspects of exposure assessment. To conclude, open questions are formulated pointing out gaps between the guidelines' principles and occupational practice, such as the impact of hot and humid environments and physical activity or controversies around ICNIRPS's reduction factors in view of assessment uncertainty in general. Thus, the article aims to provide scientific policy advisors, labor inspectors, or experts developing standards with a profound understanding about ICNIRP guidelines' applicability to assess hazards related to radiofrequency EMF in occupational settings.

Management of thoracic spinal cord injury in a professional American football athlete: illustrative case

BACKGROUND

A case of catastrophic thoracic spinal cord injury (SCI) sustained by a professional American football player with severe scoliosis is presented.

OBSERVATIONS

A 25-year-old professional football player sustained an axial loading injury while tackling. Examination revealed a T8 American Spinal Injury Association Impairment Scale grade A complete SCI. Methylprednisolone and hypothermia protocols were initiated. Computed tomography scan of the thoracic spine demonstrated T8 and T9 facet fractures on the left at the apex of a 42° idiopathic scoliotic deformity. Magnetic resonance imaging (MRI) demonstrated T2 spinal cord hyperintensity at T9. He regained trace movement of his right lower extremity over 12 hours, which was absent on posttrauma day 2. Repeat MRI revealed interval cord compression and worsening of T2 signal change at T7-T8 secondary to hematoma. Urgent decompression and fusion from T8 to T10 were performed. Additional treatment included high-dose omega-3 fatty acids and hyperbaric oxygen therapy. A 2-month inpatient spinal cord rehabilitation program was followed by prolonged outpatient physical therapy. He currently can run and jump with minimal residual distal left lower limb spasticity.

LESSONS

This is the first known football-related thoracic SCI with idiopathic scoliosis. Aggressive medical and surgical intervention with intensive rehabilitation formed the treatment protocol, with a favorable outcome achieved.

The role of therapeutic hypothermia in the management of acute spinal cord injury

This review paper investigates the history, efficacy, and administration of systemic and local hypothermia for spinal cord injury (SCI). It summarizes the published experimental and clinical evidence on hypothermia for SCI and analyzes the potential for further research. Early experimental animal research showed that local hypothermia improved recovery and gain of function after acute SCI. However, in the early 1970s, clinical research findings did not coincide with results of these animal trials, which led to a loss of interest in local hypothermia. Since the 1980s, systemic hypothermia has been successfully used to treat SCI in both animals and humans. An abundance of positive evidence suggests that clinical trials are needed to determine the effectiveness of hypothermia for SCI. As a first step, we investigated the published clinical and experimental evidence on the use of hypothermia for SCI patients, who have few available treatment options. We searched PubMed for English-language reports published from 1940 to 2016 containing terms related to SCI treatment using hypothermia. We reviewed all articles on local hypothermia and acute SCI or on systemic hypothermia and acute SCI. Bibliographies of retrieved publications were also screened for additional citations. Ninety-six papers were selected. The clinical use of hypothermia is most successful if applied according to certain optimized parameters (e.g., duration, temperature, time from injury to initiation of cooling, and rewarming time). Preliminary data suggest that modest systemic hypothermia applied for 48h provides the best therapeutic value, but the parameters for use of local hypothermia vary greatly. Experimental evidence and some clinical evidence suggest that both local hypothermia and systemic hypothermia are beneficial for acute SCI. Future research should focus on defining the optimal levels of parameters. Large, multicenter, controlled clinical trials are needed to investigate its therapeutic potential.

Therapeutic hypothermia in stroke and traumatic brain injury

Therapeutic hypothermia (TH) is considered to improve survival with favorable neurological outcome in the case of global cerebral ischemia after cardiac arrest and perinatal asphyxia. The efficacy of hypothermia in acute ischemic stroke (AIS) and traumatic brain injury (TBI), however, is not well studied. Induction of TH typically requires a multimodal approach, including the use of both pharmacological agents and physical techniques. To date, clinical outcomes for patients with either AIS or TBI who received TH have yielded conflicting results; thus, no adequate therapeutic consensus has been reached. Nevertheless, it seems that by determining optimal TH parameters and also appropriate applications, cooling therapy still has the potential to become a valuable neuroprotective intervention. Among the various methods for hypothermia induction, intravascular cooling (IVC) may have the most promise in the awake patient in terms of clinical outcomes. Currently, the IVC method has the capability of more rapid target temperature attainment and more precise control of temperature. However, this technique requires expertise in endovascular surgery that can preclude its application in the field and/or in most emergency settings. It is very likely that combining neuroprotective strategies will yield better outcomes than utilizing a single approach.

Induction of mild hypothermia by noninvasive body cooling in healthy, unanesthetized subjects

The induction of mild hypothermia has been considered as an important means to provide protection against cerebral ischemia. Yet, to date, the relative clinical efficacies of different noninvasive methods for reducing core body temperature have not been thoroughly studied. The aim of the current investigation was to compare the relative effectiveness of several noninvasive cooling techniques for reducing core temperatures in healthy volunteers. Cooling methods included convective/conductive and evaporative/conductive combinations, as well as evaporative cooling alone. Additionally, focal facial warming was employed as a means to suppress involuntary motor activity and thus better enable noninvasive cooling. Core temperatures were measured so to monitor the relative efficiencies of these induced cooling methodologies. With each employed methodology, rectal temperature reductions were induced, with combined evaporative/conductive (n=4, 1.44°C±0.99°C) and convective/conductive (n=4, 1.51°C±0.89°C) approaches yielding the largest decreases: note, that evaporative cooling alone was not as efficient in lowering core body temperature (n=10, 0.56°C±0.20°C; n=16, 0.58°C±0.27°C). In this study on healthy volunteers, the evaporative/conductive and convective/conductive combination methods were more effective in reducing core temperatures as compared with an evaporative approach alone. These therapeutic approaches for the induction of mild hypothermia (including the use of facial warming) could be employed in warranted clinical cases, importantly without the need for administration of anesthetics or paralytics.