Optimizing Cold-Water Immersion for Exercise-Induced Hyperthermia: An Evidence-Based Paper

Current State of Knowledge on the Definition, Pathophysiology, Etiology, Outcomes, and Management of Fever in the Intensive Care Unit

Fever-an elevated body temperature-is a prominent feature of a wide range of disease conditions and is a common finding in intensive care, affecting up to 70% of patients in the intensive care unit (ICU). The causes of fever in the ICU are multifactorial, and it can be due to a number of infective and noninfective etiologies. The production of fever represents a complex physiological, adaptive host response that is beneficial for host defense and survival but can be maladaptive and harmful if left unabated. Despite any cause, fever is associated with a wide range of cellular, local, and systemic effects, including multiorgan dysfunction, systemic inflammation, poor neurological recovery, and an increased risk of mortality. This narrative review presents the current state-of-the-art knowledge on the definition, pathophysiology, etiology, and outcomes of fever in the ICU and highlights evidence-based findings regarding the management of fever in the intensive care setting.

Severe Heat Stroke Resuscitation Using a Body Bag in a Community Emergency Department

Heat stroke can lead to severe complications such as end-organ damage and death. The primary treatment modality for heat stroke is rapid cold-water immersion to lower the patient's body temperature. This typically requires a large bath to place the patient in, which may not be available in small or community emergency departments. Although rarely present in the literature, a body bag for cold-water immersion can be used if a bath is not available. Here, we present a case of a 63-year-old male who presented to the emergency department unresponsive with hyperthermia after a heat wave warning was issued. After a thorough workup and imaging, the patient was given IV saline and naloxone, which did not improve his condition. Therefore, the patient was placed in a body bag filled with cold water and ice until his body temperature reduced to 100°F, after which he was removed and closely monitored. The patient was safely discharged and only required repeat lab work three days after discharge. This case highlights a unique technique that emergency physicians can utilize in scenarios where a typical cold-water immersion setup and execution are not possible.

Topical Analgesic Containing Methyl Salicylate and L-Menthol Accelerates Heat Loss During Skin Cooling for Exercise-Induced Hyperthermia

Hyperthermia impairs physical performance and, when prolonged, results in heat stroke or other illnesses. While extensive research has investigated the effectiveness of various cooling strategies, including cold water immersion and ice-suit, there has been little work focused on overcoming the cutaneous vasoconstriction response to external cold stimulation, which can reduce the effectiveness of these treatments. Over-the-counter (OTC) topical analgesics have been utilized for the treatment of muscle pain for decades; however, to date no research has examined the possibility of taking advantage of their vasodilatory functions in the context of skin cooling. We tested whether an OTC analgesic cream containing 20% methyl salicylate and 6% L-menthol, known cutaneous vasodilators, applied to the skin during skin cooling accelerates heat loss in exercise-induced hyperthermia. Firstly, we found that cutaneous application of OTC topical analgesic cream can attenuate cold-induced vasoconstriction and enhance heat loss during local skin cooling. We also revealed that core body heat loss, as measured by an ingestible telemetry sensor, could be accelerated by cutaneous application of analgesic cream during ice-suit cooling in exercise-induced hyperthermia. A blunted blood pressure response was observed during cooling with the analgesic cream application. Given the safety profile and affordability of topical cutaneous analgesics containing vasodilatory agents, our results suggest that they can be an effective and practical tool for enhancing the cooling effects of skin cooling for hyperthermia.

Efficiency of three cooling methods for hyperthermic military personnel linked to water availability

PURPOSE

Three feasible cooling methods for treatment of hyperthermic individuals in the military, that differed considerably in water volume needed (none to ~80 L), were evaluated.

METHODS

Ten male soldiers were cooled following exercise-induced hyperthermia (rectal temperature (T_re) ∼39.5 °C) using ventilation by fanning (1.7 m s^-1), ventilation by fanning (1.7 m s^-1) while wearing a wet t-shirt (250 mL-27 °C water) and tarp assisted cooling with oscillations (80 L of 27.2 ± 0.5 °C water; TACO).

RESULTS

Cooling rates were higher using TACO (0.116 ± 0.032 °C min^-1) compared to ventilation (0.065 ± 0.011 °C min^-1, P<0.001) and ventilation in combination with a wet t-shirt (0.074 ± 0.020 °C min^-1, P=0.002). Time to cool (TTC) to T_re=38.2 °C for TACO was shorter (14 ± 4 min) compared to ventilation only (20 ± 5 min; P=0.018), but not to ventilation while wearing a wet t-shirt (18 ± 6 min; P=0.090).

CONCLUSIONS

TACO may be an acceptable, efficient and feasible cooling method in case of exertional heat stroke. However, in case of limited water availability, transportat should be prioritized, and cooling of any form should be implemented while waiting for and during transport.

Fundamental Concepts of Human Thermoregulation and Adaptation to Heat: A Review in the Context of Global Warming

The international community has recognized global warming as an impending catastrophe that poses significant threat to life on earth. In response, the signatories of the Paris Agreement (2015) have committed to limit the increase in global mean temperature to < 1.5 °C from pre-industry period, which is defined as 1950-1890. Considering that the protection of human life is a central focus in the Paris Agreement, the naturally endowed properties of the human body to protect itself from environmental extremes should form the core of an integrated and multifaceted solution against global warming. Scholars believe that heat and thermoregulation played important roles in the evolution of life and continue to be a central mechanism that allows humans to explore, labor and live in extreme conditions. However, the international effort against global warming has focused primarily on protecting the environment and on the reduction of greenhouse gases by changing human behavior, industrial practices and government policies, with limited consideration given to the nature and design of the human thermoregulatory system. Global warming is projected to challenge the limits of human thermoregulation, which can be enhanced by complementing innate human thermo-plasticity with the appropriate behavioral changes and technological innovations. Therefore, the primary aim of this review is to discuss the fundamental concepts and physiology of human thermoregulation as the underlying bases for human adaptation to global warming. Potential strategies to extend human tolerance against environmental heat through behavioral adaptations and technological innovations will also be discussed. An important behavioral adaptation postulated by this review is that sleep/wake cycles would gravitate towards a sub-nocturnal pattern, especially for outdoor activities, to avoid the heat in the day. Technologically, the current concept of air conditioning the space in the room would likely steer towards the concept of targeted body surface cooling. The current review was conducted using materials that were derived from PubMed search engine and the personal library of the author. The PubMed search was conducted using combinations of keywords that are related to the theme and topics in the respective sections of the review. The final set of articles selected were considered "state of the art," based on their contributions to the strength of scientific evidence and novelty in the domain knowledge on human thermoregulation and global warming.

The usage of multidisciplinary physical therapies at the Rio de Janeiro 2016 Olympic Summer Games: an observational study

BACKGROUND

This observational research study analyses the uptake of physical therapies treatments in the Polyclinic during the Rio 2016 Olympic Games.

OBJECTIVE

To describe the usage of physical therapies services - physical therapy, osteopath, chiropractic, and sports massage - by athletes and non-athletes and across different sports.

METHODS

The multidisciplinary team of physical therapies recorded treatment modalities, information on provider discipline and reason for attendance, in an Electronic Medical Record system throughout the 32 days of operation of the Olympic Polyclinic. Cold-therapy total immersion ice baths (TIIB) were provided as part of the services, but were reported and analysed separately.

RESULTS

There were 4993 encounters (4038 athletes, 955 non-athlete encounters). 1395 athletes (12.4% of all athletes) and 393 non-athletes sought treatment. For all four provider disciplines, in addition to TIIB, the primary reason for athlete attendance was for recovery (52% of all encounters), followed by injury treatment (30%), and maintenance (16%). Athletes reported "injury" as the main reason for physical therapy (92% of all encounters, 2.8 encounters per athlete), chiropractic (94%, 1.9) and osteopathy (91%, 1.8) visits. Almost all TIIB visits were used for recovery (98% of all TIIB encounters; 2.1 encounters per athlete). Athletes from handball (37% of all handball athletes), followed by judo (22%), and athletics (21%), presented the largest user groups.

CONCLUSION

This Olympic Polyclinic study evaluates the physical therapies' activity, and athlete's reason for use of the multidisciplinary physical therapies team, including total immersion ice bath provision. These results emphasise the importance of a multidisciplinary approach.