Therapeutic temperature modulation in neurocritical care

Sedative Agents, Synthetic Torpor, and Long-Haul Space Travel-A Systematic Review

BACKGROUND

With renewed interest in long-duration space missions, there is growing exploration into synthetic torpor as a countermeasure to mitigate physiological stressors. Sedative agents, particularly those used in clinical anesthesia, have been proposed to replicate aspects of natural torpor, including reduced metabolic rate, core temperature, and brain activity.

OBJECTIVES

This systematic review aims to evaluate the potential of sedative agents to induce torpor-like states suitable for extended spaceflight. The review specifically investigates their pharmacokinetics, pharmacodynamics, and performance under space-related stressors such as microgravity and ionizing radiation.

METHODS

We conducted a comprehensive search across multiple databases (e.g., PubMed, Scopus, Web of Science) for studies published from 1952 to 2024. Eligible studies included experimental, preclinical, and clinical investigations examining sedative agents (especially inhalation anesthetics) in the context of metabolic suppression or space-relevant conditions. Screening, selection, and data extraction followed PRISMA guidelines.

RESULTS

Out of the screened records, 141 studies met the inclusion criteria. These were thematically grouped into seven categories, including torpor physiology, anesthetic uptake, metabolism, and inhalation anesthetics. Sedative agents showed variable success in inducing torpor-like states, with inhalation anesthetics demonstrating promising metabolic effects. However, concerns remain regarding delivery methods, safety, rewarming, and the unknown effects of prolonged use in space environments.

CONCLUSIONS

Sedative agents, particularly volatile anesthetics, hold potential as tools for inducing synthetic torpor in space. Nevertheless, significant knowledge gaps and technical challenges persist. Further targeted research is required to optimize these agents for safe, controlled use in spaceflight settings.

Retrospective Analysis of Esophageal Heat Transfer for Active Temperature Management in Post-cardiac Arrest, Refractory Fever, and Burn Patients

Core temperature management is an important aspect of critical care; preventing unintentional hypothermia, reducing fever, and inducing therapeutic hypothermia when appropriate are each tied to positive health outcomes. The purpose of this study is to evaluate the performance of a new temperature management device that uses the esophageal environment to conduct heat transfer. De-identified patient data were aggregated from three clinical sites where an esophageal heat transfer device (EHTD) was used to provide temperature management. The device was evaluated against temperature management guidelines and best practice recommendations, including performance during induction, maintenance, and cessation of therapy. Across all active cooling protocols, the average time-to-target was 2.37 h and the average maintenance phase was 22.4 h. Patients spent 94.9% of the maintenance phase within ±1.0°C and 67.2% within ±0.5°C (574 and 407 measurements, respectively, out of 605 total). For warming protocols, all of the patient temperature readings remained above 36°C throughout the surgical procedure (average 4.66 h). The esophageal heat transfer device met performance expectations across a range of temperature management applications in intensive care and burn units. Patients met and maintained temperature goals without any reported adverse events.

Shivering Treatments for Targeted Temperature Management: A Review

BACKGROUND

Shivering is common during targeted temperature management, and control of shivering can be challenging if clinicians are not familiar with the available options and recommended approaches.

PURPOSE

The purpose of this review was to summarize the most relevant literature regarding various treatments available for control of shivering and suggest a recommended approach based on latest data.

METHODS

The electronic databases PubMed/MEDLINE and Google Scholar were used to identify studies for the literature review using the following keywords alone or in combination: "shivering treatment," "therapeutic hypothermia," "core temperature modulation devices," and "targeted temperature management."

RESULTS

Nonpharmacologic methods were found to have a very low adverse effect profile and ease of use but some limitations in complete control of shivering. Pharmacologic methods can effectively control shivering, but some have adverse effects, such that risks and benefits to the patient have to be balanced.

CONCLUSION

An approach is provided which suggests that treatment for shivering control in targeted temperature management should be initiated before the onset of therapeutic hypothermia or prior to any attempt at lowering patient core temperature, with medications including acetaminophen, buspirone, and magnesium sulfate, ideally with the addition of skin counterwarming. After that, shivering intervention should be determined with the help of a shivering scale, and stepwise escalation can be implemented that balances shivering treatment with sedation, aiming to provide the most shivering reduction with the least sedating medications and reserving paralytics for the last line of treatment.

Induced Hypothermia in Neurocritical Care: A Review

Induced hypothermia (IH) continues to become a more prevalent treatment modality in neurocritical care. Reducing core temperature has been shown to protect brain tissue during injury and disease. IH has been particularly beneficial in the medical management of refractory intracranial hypertension and malignant cerebral edema. These pathologies are often the result of diffuse cerebral edema after traumatic brain injury, malignant ischemic stroke, or intracerebral hemorrhage. Although there are many benefits to IH, it is not without complications. Chief among these is shivering, which decreases oxygen delivery to brain tissue, increases metabolic demands, and consequently reduces nutrient delivery. This article will review indications for IH administration, methods of providing IH, nursing responsibilities, and identifying and/or managing complications.