Mechanisms of action, physiological effects, and complications of hypothermia. Crit Care Med. 2009;37:S186-S202. [PMID: 19535947 DOI: 10.1097/ccm.0b013e3181aa5241]

Anesthetic Management for Proximal Aortic Repair

Surgical repair of the proximal aorta is a complex endeavor, requiring cardiopulmonary bypass (CPB) and often the use of hypothermic circulatory arrest (HCA). In addition to the normal considerations for patients undergoing cardiopulmonary bypass, additional challenges include cerebral and end-organ protection during periods of circulatory arrest. This review aims to provide an up-to-date, evidence-based review on anesthetic management for proximal aortic repair.

Extravascular Temperature Control for Heatstroke With Multi-Organ Failure: A Survivor's Case Report

Heatstroke is caused by a loss of control over body temperature. There is a high risk of death if it is not treated quickly and properly. In this article, we report a clinical case of a 21-year-old male patient treated for heatstroke with extravascular temperature control. The patient lost consciousness after being out in the sun for more than 2 h. His body temperature was 41°C upon admission to the district hospital, and then 4 h later, he was transferred to our department. The patient was administered extravascular temperature control with a target temperature of 33°C within 24 h. We rewarmed at a rate of 0.25°C/h to 37°C within 16 h, and the patient was taken off sedation to assess consciousness. After 2 days, the patient's consciousness improved from GCS 5 to 10, and the patient maintained a body temperature of 37°C for another 4 days. However, the patient still had liver failure and severe coagulation disorders on day 5. He was given fresh frozen plasma or plasma exchange. The patient was extubated after 8 days and discharged from the hospital after 24 days of treatment. In conclusion, extravascular temperature control can be used effectively to treat heatstroke, combined with the treatment of damaged organs.

Progress in Research on Regulated Cell Death in Cerebral Ischaemic Injury After Cardiac Arrest

Ischaemic damage to the brain is the main cause of brain injury after cardiac arrest. The current treatment focuses on early reperfusion, but reperfusion tends to cause reperfusion injury, which is a significant problem. Cell death is an irreversible and normal end to cell life, playing key roles in maintaining the homeostasis and development of multicellular organisms. To date, cell death can be classified into two categories: accidental cell death (ACD) and regulated cell death (RCD). Cell death plays an indispensable role in cerebral ischaemia injury. An increasing number of scholars are exploring the mechanisms and sites of cell death during targeted inhibition of cerebral ischaemia to treat cerebral ischaemia injury. In addition to the established cell death pathways, namely, the apoptosis, pyroptosis and necroptosis pathways, ferroptosis and cuproptosis pathways have been discovered. This article reviews the cell death pathways involved in ischaemic brain injury, discusses the roles played by these death modalities, and suggests therapeutic directions for future targeting of cell death sites.

Hypothermia: Pathophysiology and the propensity for infection

Hypothermia in combination with infection presents a complex challenge in clinical and battlefield medicine. Multifaceted physiological and immunological consequences of hypothermia drastically change the risk, progression, and treatment of a concomitant infection. Managing hypothermia and infection in extreme cold settings is particularly relevant in an era with increased risk of military operations in Polar climates. Here, we discuss the elevated instance of infection during accidental and therapeutic hypothermia and speculate how a compromised immune system may contribute. We focus on skin and soft tissue infections and sepsis, which are among the serious infectious complications of hypothermia and battlefield injuries. We also present the challenges associated with treating infections under hypothermic conditions. Finally, we advocate for a renewed focus on identifying causal relationships between hypothermia and infection risk and assessing established infection treatment regiments in hypothermic patients to enhance trauma management and survival outcomes in hypothermia-related injuries.

Temperature control during pars plana vitrectomy

PURPOSE

To evaluate the impact of temperature-controlled pars plana vitrectomy (PPV) on structural and functional outcomes in a rabbit eye model in vivo.

METHODS

Ten healthy New Zealand White rabbits underwent temperature-controlled PPV in the right eye (group A), using a device specifically designed to heat the infusion fluid/air and integrated into the vitrectomy machine, and conventional PPV in the left eye (group B). Both eyes received ophthalmic examination and electroretinography (ERG) before and 1 week postoperatively. After 1-week ERG, rabbits were enucleated and then sacrificed. Histological and immunohistochemical examinations were performed on enucleated eyes and expression of glial fibrillary acidic protein (GFAP) and vimentin investigated.

RESULTS

Postoperatively, only group B showed significantly decreased amplitude and increased latency of a-wave at 3 cd·s/m2 (p = 0.001 and 0.005, respectively). Significant increase of b-wave latency at 0.01 cd·s/m2 was detected in both groups (p = 0.019 and 0.023, respectively). Postoperatively, amplitude of oscillatory potentials (OPs) increased significantly in group A (p = 0.023) and decreased in group B. In both groups, OPs latency significantly increased at 1-week test (P < 0.05). A greater number of eyes without structural retinal alterations was detected in group A compared to group B (6 vs 5, respectively). GFAP expression was higher in group B than group A, even if the difference was not statistically significant.

CONCLUSION

Temperature-controlled PPV resulted in more favorable functional and structural outcomes in rabbit eyes compared with conventional PPV, supporting the potential beneficial role of the intraoperative management of intraocular temperature in vitreoretinal surgery.

Effects of intraoperative hypothermia on patients undergoing laparoscopic surgery: A retrospective cohort study

OBJECTIVE

This study aims to explore the association between intraoperative hypothermia and outcomes in adult patients undergoing laparoscopic surgery.

METHODS

A retrospective analysis of 2048 adult laparoscopic surgery patients treated between 2020 and 2021 was conducted at Songklanagarind Hospital, Thailand. Intraoperative hypothermia, defined as a core temperature below 36°C, was recorded as either one or more than one episode. Patient demographics, clinical information and postoperative outcomes were extracted from the hospital information system. The outcomes were intraoperative and postoperative cardiac arrhythmias, postoperative oxygen requirement, length of post-anesthetic care unit (PACU) stay, and length of hospital stay. Univariate and multivariate logistic/linear regression models were fit to assess the association between hypothermia and outcomes, presented as odds ratio (OR) or beta-coefficient (β) with 95% confidence interval (CI).

RESULTS

The incidence of intraoperative hypothermia was 34.9%, with 688 experiencing one episode and 27 experiencing multiple episodes. On multivariate analysis, patients with one and more than one episode of hypothermia had an increased risk of intraoperative cardiac arrhythmia compared to normothermic patients (OR [95%CI]: 1.67[1.24,2.25] and 3.65[1.53,8.74], respectively, P<0.001). Normothermic patients and hypothermic patients with more than one-episode had a higher odds of postoperative oxygen requirement compared to hypothermic patients with only one episode (OR [95%CI]:1.32[1.02,1.7] and 2.64[1.1,6.32], respectively, P = 0.019). Hypothermic patients with one and more than one-episode also had longer PACU stays compared to normothermic patients (β[95%CI]:3.82[1.34,6.29] and 12.43[2.29,22.57] minutes, respectively, P = 0.001). No significant differences were observed in the other outcomes.

CONCLUSIONS

Intraoperative hypothermia in laparoscopic surgery is associated with a higher likelihood of intraoperative cardiac arrhythmias, prolonged PACU stay and higher postoperative oxygen requirement. Further research and prospective studies are warranted to validate these results and develop strategies to manage intraoperative hypothermia effectively.

S100A8-CAMKK2-AMPK axis confers the protective effects of mild hypothermia against cerebral ischemia-reperfusion injury in rats

To investigate the neuroprotective mechanism of mild hypothermia (MH) in ameliorating cerebral ischemia reperfusion (IR) injury. The Pulsinelli's four-vessel ligation method was utilized to establish a rat model of global cerebral IR injury. To investigate the role of S100A8 in MH treatment of cerebral IR injury, hippocampus-specific S100A8 loss or gain of function was achieved using an adeno-associated virus system. We examined the effect of S100A8 over-expression or knock-down on the function of the SH-SY5Y cell line subjected to oxygen-glucose deprivation reoxygenation (OGDR) injury under MH treatment and delved into the underlying mechanisms. MH significantly ameliorates IR-induced neurological injury in the brain. Similarly to MH, knock-down of S100A8 significantly reduced neuronal oxidative stress, attenuated mitochondrial damage, inhibited apoptosis, and improved cognitive function in IR rats. Conversely, over-expression of S100A8 attenuated MH's protective effect and aggravated brain IR injury. In vitro, low expression of S100A8 significantly inhibited the decline in mitochondrial membrane potential induced by OGDR, reduced oxidative stress response, and decreased cell apoptosis, acting as a protective agent nearly equivalent to MH in SH-SY5Y cells. However, over-expression of S100A8 significantly inhibited these protective effects of MH. Mechanistically, MH down-regulated S100A8 expression, enhancing mitochondrial function via activation of the CAMKK2/AMPK signaling pathway. Moreover, with MH treatment, the administration of CAMKK2 and AMPK inhibitors STO-609 and Dorsomorphin significantly increased oxidative stress, mitochondrial damage, and cell apoptosis, thereby diminishing MH's neuroprotective effect against cerebral IR injury. Our study identified S100A8 as a master regulator that enables MH to ameliorate neurological injury during the early stage of cerebral IR injury by enhancing mitochondrial function. By targeting the S100A8-initiated CAMKK2/AMPK signaling pathway, we may unlock a novel therapeutic intervention or develop a refined MH therapeutic strategy against cerebral IR injury.

The effect of thermoelectric craniocerebral cooling device on protecting brain functions in post-cardiac arrest syndrome

Aim

This study aimed to protect brain functions in patients who experienced in-hospital cardiac arrest through the application of local cerebral hypothermia. By utilizing a specialized thermal hypothermia device, this approach sought to mitigate ischemic brain injury associated with post-cardiac arrest syndrome, enhance survival rates, and improve neurological outcomes as measured by standardized scales.

Methods

A prospective, single-center cohort study was conducted involving patients aged ≥18 years who experienced in-hospital cardiac arrest and achieved return of spontaneous circulation (ROSC). Patients were cooled using a hypothermia helmet to achieve a target temperature of 32°C-34°C, maintained for 36-72 h, followed by controlled rewarming and normothermia for 72 h. Neurological recovery was assessed using the Cerebral Performance Category (CPC) scale, where CPC 1-2 denotes good recovery and CPC 3-5 indicates poor outcomes. Body temperature, hemodynamic parameters, biochemical changes, and survival data were meticulously recorded and analyzed. Statistical analysis included paired t-tests to compare pre- and post-treatment data.

Results

Of 116 cardiac arrest cases, 30 (25.86%) were in-hospital, and 16 (53.33%) of these achieved ROSC. Among the patients, 62.5% underwent emergency coronary angiography due to ST-elevation myocardial infarction (STEMI). The mean time to hypothermia initiation was 32.9 ± 13.5 min, with hypothermia maintained for 58 ± 6.4 h. Neurological outcomes were favorable, with 62.5% of patients achieving CPC scores of 1 or 2, indicating functional recovery and independence. In contrast, CPC scores of 3 or higher were observed in 37.5% of patients, reflecting varying degrees of disability. Biochemical analysis revealed significant decreases in sodium, potassium, calcium, and magnesium levels, alongside increased urea and creatinine concentrations. Hemodynamic improvements included elevated systolic blood pressure and heart rate, while left ventricular ejection fraction remained stable. Overall survival was 75%, and the majority (62.5%) of survivors were discharged without significant neurological deficits.

Conclusion

The findings suggest that early and targeted application of craniocerebral thermal hypothermia has the potential to improve survival and preserve neurological function in post-cardiac arrest syndrome. The high rates of favorable outcomes, as reflected by CPC scores, underscore the neuroprotective effects of localized hypothermia. Further large-scale, multicenter trials are recommended to validate these promising results and refine protocols for optimal clinical application.

Advanced age and neurological recovery in elderly patients with out-of-hospital cardiac arrest treated with targeted temperature management: a nationwide population‑based registry study 2016-2020

The likelihood of neurological recovery after out-of-hospital cardiac arrest (OHCA) may be influenced by advanced age. This study aims to evaluate the impact of advanced age on neurological recovery in elderly OHCA survivors treated with targeted temperature management (TTM). This retrospective observational study, using a nationwide population-based OHCA registry, was conducted from January 2016 to December 2020. Non-traumatic elderly (≥ 65 years) comatose OHCA survivors treated with TTM were categorized according to age (65-69, 70-74, 75-79, and ≥ 80 years). Among 23,336 admitted OHCA patients, 3,398 were treated with TTM. Excluding 2,033 non-elderly patients, 1,365 were analyzed. Among the four groups, the rate of good neurological outcomes decreased by advanced age (24.2%, 16.1%, 11.4%, and 5.9%, respectively), which was also observed after subgroup analysis based on the initial shockable (40.6%, 31.5%, 28.6%, and 14.9%, respectively) and non-shockable rhythm (10.6%, 7.2%, 4.1%, and 3.4%, respectively). Multivariate analysis showed the adjusted odds ratio (aOR) for good neurological outcome decreased as age increased (65-69: reference, 70-74: aOR 0.70, 75-79: aOR 0.49, and ≥ 80 years: aOR 0.25). The optimal age cutoffs for good outcomes in elderly OHCA survivors with shockable and non-shockable rhythm were 77 and 72 years, respectively. The neurologic recovery rate in OHCA survivors treated with TTM gradually decreased with increasing age. However, even patients aged ≥ 80 years with shockable rhythm had a good neurologic outcome of 14.9% compared with patients aged 65-69 years with non-shockable rhythm (10.6%).

Blood glucose levels in out-of-hospital cardiac arrest undergoing targeted temperature management and ECPR

AIM

Targeted temperature management (TTM) for patients undergoing extracorporeal cardiopulmonary resuscitation (ECPR) has not been fully studied. This study aimed to investigate the association between blood glucose levels during TTM and neurological outcomes in out-of-hospital cardiac arrest (OHCA) patients undergoing ECPR.

METHODS

This was a secondary analysis of the SAVE-J II study, a retrospective, multicenter study of OHCA patients treated with ECPR in Japan. The average inpatient blood glucose levels for days 2-4 was divided into four categories (Category 1: 80-140 mg/dL, Category 2: 140-180 mg/dL, Category 3: 180-300 mg/dL, and Category 4: 300 mg/dL or more). The primary outcome was a favorable neurological status.

RESULTS

Multivariable analyses were performed for 891 enrolled patients. There were 153, 278, 142, and 18 patients in categories 1, 2, 3, and 4, respectively. Category 3 blood glucose levels were significantly more associated with unfavorable outcomes than Category 2 (adjusted OR, 0.45; 95 % CI, 0.24-0.81; p = 0.01). Although not statistically significant, Category 1 blood glucose levels may indicate a potential trend toward favorable neurological outcomes compared to Category 2. [adjusted OR, 1.41; 95 % CI, 0.96-2.08; p = 0.079].

CONCLUSIONS

During TTM, blood glucose levels of 180 mg/dL or more were significantly more associated with unfavorable outcomes than those of 140-180 mg/dL, in patients on ECPR. Further studies to evaluate more intensive glucose control than the current target of 140-180 mg/dL are required.

The 100 most-cited articles in hypothermic brain protection journals: a bibliometric and visualized analysis

Introduction

A bibliometric analysis is used to assess the impact of research in a particular field. However, a specialized bibliometric analysis focused on hypothermic brain protection has not yet been conducted. This study aimed to identify the 100 most-cited articles published in the field of hypothermic brain protection and analyze their bibliometric characteristics.

Methods

After screening articles from the Web of Science citation database, complete bibliographic records were imported into Python for data extraction. The following parameters were analyzed: title, author's name and affiliation, country, publication year, publication date, first author, corresponding author, study design, language, number of citations, journal impact factors, keywords, Keywords Plus®, and research topic.

Results

The 100 articles were published between 1990 and 2016. The citation frequency for each publication ranged from 86 to 470. Among the 100 articles, 73 were original articles, 18 were review articles, 8 were clinical articles, and 1 was editorial material. These papers were published in 37 journals, with the Journal of Cerebral Blood Flow and Metabolism being the most prolific with 15 papers. Eighteen countries contributed to the 100 publications, 51 of which were from United States institutions. In addition, the keywords in the Sankey plot indicated that research in the field of hypothermic brain protection is growing deeper and overlapping with other disciplines.

Discussion

The results provide an overview of research on hypothermic brain protection, which may help researchers better understand classical research, historical developments, and new discoveries, as well as providing ideas for future research.

The forensic significance of core temperature in identifying primary and secondary hypothermia as a cause of death: A pilot study on Wistar rats

INTRODUCTION

Hypothermia is defined as a body core temperature below 35 °C and can be caused by internal or external stress. Primary hypothermia is caused by excessive exposure to low environmental temperature without any medical conditions prior to that. Secondary hypothermia is caused by alteration in thermoregulation by disease, trauma, surgery, drugs, or infections. The aim of the research is to investigate core temperature values in rats subjected to specific water temperatures at five different time points. It focuses on distinguishing between primary and secondary hypothermia in these rats.

METHODS

The total 21 Wistar rats were divided into three experimental groups as: Control group rats exposed only to hypothermic condition (n = 7); Alcohol + hypothermia (n = 7); and Benzodiazepines + hypothermia (n = 7). The temperature spots analyzed in the study were: normal core temperature, core temperature during injection of 0,3 ketamine, temperature of immersion and the temperature at the onset of hypothermia and temperature at the time of death.

RESULTS

In our study the comparative analysis of body temperatures at various time points following submersion in water revealed significant differences among the study groups treated with either alcohol or benzodiazepines and the control group. Notable differences were observed in baseline temperature, post-anesthesia induction temperature, and immediate post-submersion temperature. Specifically, significant differences were discovered among the alcohol and benzodiazepine groups (p < 0.001) and ranging from the alcohol and control groups (p < 0.001). The analysis of survival times following induced hypothermia revealed a statistically significant difference among the three experimental groups (p = 0.04), though subsequent post-hoc comparisons did not demonstrate significant differences in mean survival times.

CONCLUSION

There is a difference in survival time between primary and secondary hypothermia groups, depending on consumption and intoxication with alcohol or benzodiazepines. The analysis of survival times following induced hypothermia showed a statistically significant difference among the groups.

A review on targeted temperature management for cardiac arrest and traumatic brain injury

Therapeutic hypothermia inhibits organ damage by suppressing metabolism, which makes it a therapy of choice for treating various diseases. Specifically, it is often used to treat conditions involving central nervous system disorders where it is expected to positively impact functional prognosis. Although keeping the body temperature at a hypothermic level has been conventionally used, how to manage the body temperature correctly remains a topic of debate. Recently, the concept of temperature management has been proposed to improve the quality of body temperature control and avoid hyperthermia. This review focuses on the effect of temperature on the central nervous system in conditions involving central nervous system disorders and the practice of temperature management in clinical situations.

Moderate Hypothermia Alleviates Sepsis-Associated Acute Lung Injury by Suppressing Ferroptosis Induced by Excessive Inflammation and Oxidative Stress via the Keap1/GSK3β/Nrf2/GPX4 Signaling Pathway

Purpose

Sepsis-associated acute lung injury (SA-ALI) is a common complication in patients with sepsis, contributing to high morbidity and mortality. Excessive inflammation and oxidative stress are crucial contributors to lung injury in sepsis. This study aims to examine the protective effects of moderate hypothermia on SA-ALI and explore the underlying mechanisms.

Methods

Sepsis was induced in rats through cecal ligation and puncture followed by intervention with moderate hypothermia (32-33.9°C). Blood, bronchoalveolar lavage fluid, and lung tissues were collected 12 hours post-surgery. Inflammatory responses, oxidative injury, SA-ALI-related pathophysiological processes, and Keap1/GSK3β/Nrf2/GPX4 signaling in septic rats were observed by ELISA, lung W/D ratio, immunohistochemistry, immunofluorescence, histological staining, Western blotting, RT-qPCR, and TEM assays.

Results

Moderate hypothermia treatment alleviated lung injury in septic rats, reflected in amelioration of pathological changes in lung structure and improved pulmonary function. Further, moderate hypothermia reduced arterial blood lactate production and suppressed the expression of inflammatory factors IL-1β, IL-6, and TNF-α; downregulated ROS, MDA, and redox-active iron levels; and restored GSH and SOD content. TEM results demonstrated that moderate hypothermia could mitigate ferroptosis in PMVECs within lung tissue. The underlying mechanism may involve regulation of the Keap1/Nrf2/SLC7A11/GPX4 signaling pathway, with the insulin pathway PI3K/Akt/GSK3β also playing a partial role.

Conclusion

Collectively, we illustrated a novel potential therapeutic mechanism in which moderate hypothermia could alleviate ferroptosis induced by excessive inflammation and oxidative stress via the regulation of Keap1/GSK3β/Nrf2/GPX4 expression, hence ameliorating acute lung injury in sepsis.

Alteration in cerebrospinal fluid flow based on the neurological prognosis of out-of-hospital cardiac arrest patients

We evaluated alterations in cerebrospinal fluid (CSF) flow based on the neurological prognosis of out-of-hospital cardiac arrest (OHCA) patients. This prospective observational study was conducted from May 2023 to June 2024. Stroke distance was measured using magnetic resonance imaging flowmetry immediately and at 72 h after return of spontaneous circulation (ROSC), with negative values indicating caudocranial direction. The caudocranial direction of CSF flow was observed in 17 (56.7%) patients immediately after ROSC, and in 20 (66.7%) patients at 72 h after ROSC. There was no significant difference in the occurrence of caudocranial CSF flow immediately after ROSC between the groups with good and poor neurological prognosis [6 (50.0%) vs. 11 (61.1%); p = 0.55]. However, the occurrence of caudocranial CSF flow at 72 h after ROSC was significantly higher in the group with poor neurological prognosis compared to the group with good neurological prognosis [3 (25.0%) vs. 17 (94.4%); p < 0.001]. This study demonstrated that the occurrence of caudocranial CSF flow at 72 h after ROSC was significantly higher in the group with poor neurological prognosis compared to the group with good neurological prognosis.

Combination of Hydrogen Inhalation and Hypothermic Temperature Control After Out-of-Hospital Cardiac Arrest: A Post hoc Analysis of the Efficacy of Inhaled Hydrogen on Neurologic Outcome Following Brain Ischemia During PostCardiac Arrest Care II Trial

OBJECTIVE

The Efficacy of Inhaled Hydrogen on Neurologic Outcome Following Brain Ischemia During Post-Cardiac Arrest Care (HYBRID) II trial (jRCTs031180352) suggested that hydrogen inhalation may reduce post-cardiac arrest brain injury (PCABI). However, the combination of hypothermic target temperature management (TTM) and hydrogen inhalation on outcomes is unclear. The aim of this study was to investigate the combined effect of hydrogen inhalation and hypothermic TTM on outcomes after out-of-hospital cardiac arrest (OHCA).

DESIGN

Post hoc analysis of a multicenter, randomized, controlled trial.

SETTING

Fifteen Japanese ICUs.

PATIENTS

Cardiogenic OHCA enrolled in the HYBRID II trial.

INTERVENTIONS

Hydrogen mixed oxygen (hydrogen group) versus oxygen alone (control group).

MEASUREMENTS AND MAIN RESULTS

TTM was performed at a target temperature of 32-34°C (TTM32-TTM34) or 35-36°C (TTM35-TTM36) per the institutional protocol. The association between hydrogen + TTM32-TTM34 and 90-day good neurologic outcomes was analyzed using generalized estimating equations. The 90-day survival was compared between the hydrogen and control groups under TTM32-TTM34 and TTM35-TTM36, respectively. The analysis included 72 patients (hydrogen [ n = 39] and control [ n = 33] groups) with outcome data. TTM32-TTM34 was implemented in 25 (64%) and 24 (73%) patients in the hydrogen and control groups, respectively ( p = 0.46). Under TTM32-TTM34, 17 (68%) and 9 (38%) patients achieved good neurologic outcomes in the hydrogen and control groups, respectively (relative risk: 1.81 [95% CI, 1.05-3.66], p < 0.05). Hydrogen + TTM32-TTM34 was independently associated with good neurologic outcomes (adjusted odds ratio 16.10 [95% CI, 1.88-138.17], p = 0.01). However, hydrogen + TTM32-TTM34 did not improve survival compared with TTM32-TTM34 alone (adjusted hazard ratio: 0.22 [95% CI, 0.05-1.06], p = 0.06).

CONCLUSIONS

Hydrogen + TTM32-TTM34 was associated with improved neurologic outcomes after cardiogenic OHCA compared with TTM32-TTM34 monotherapy. Hydrogen inhalation is a promising treatment option for reducing PCABI when combined with TTM32-TTM34.

Optimal Targeted Temperature Management for Patients with Post-Cardiac Arrest Syndrome

Background: To prevent hypoxic-ischemic brain damage in patients with post-cardiac arrest syndrome (PCAS), international guidelines have emphasized performing targeted temperature management (TTM). However, the most optimal targeted core temperature and cooling duration reached no consensus to date. This study aimed to clarify the optimal targeted core temperature and cooling duration, selected according to the time interval from collapse to return of spontaneous circulation (ROSC) in patients with PCAS due to cardiac etiology. Methods: Between 2014 and 2020, the targeted core temperature was 34 °C or 35 °C, and the cooling duration was 24 h. If the time interval from collapse to ROSC was within 20 min, we performed the 35 °C targeted core temperature (Group A), and, if not, we performed the 34 °C targeted core temperature (Group B). Between 2009 and 2013, the targeted core temperature was 34 °C, and the cooling duration was 24 or 48 h. If the interval was within 20 min, we performed the 24 h cooling duration (Group C), and, if not, we performed the 48 h cooling duration (Group D). Results: The favorable neurological outcome rates at 30 days following cardiac arrest were 45.7% and 45.5% in Groups A + B and C + D, respectively (p = 0.977). In patients with ROSC within 20 min, the favorable neurological outcome rates at 30 days following cardiac arrest were 75.6% and 86.4% in Groups A and C, respectively (p = 0.315). In patients with ROSC ≥ 21 min, the favorable neurological outcome rates at 30 days following cardiac arrest were 29.3% and 18.2% in Groups B and D, respectively (p = 0.233). Conclusions: Selecting the optimal target core temperature and the cooling duration for TTM, according to the time interval from collapse to ROSC, may be helpful in patients with PCAS due to cardiac etiology.

Progress of Brain Hypothermia Treatment for Severe Subarachnoid Hemorrhage-177 Cases Experienced and a Narrative Review

The benefits of hypothermia for the treatment of subarachnoid hemorrhage (SAH) remain controversial. In 1999, we initiated brain hypothermia treatment (BHT) in the hyperacute phase to mitigate the evolution of early brain injury in patients with World Federation of Neurological Surgeons (WFNS) grade V SAH. In June 2014, we introduced endovascular cooling to maintain normothermia for seven days following the initial BHT period. Immediately after the decision to treat the sources of bleeding, cooling was initiated, with a target temperature of 33-34°C. Bleeding sources were extirpated primarily by clipping with decompressive craniectomy. Patients were rewarmed at a rate of ≤1°C/day after ≥48 hours of surface cooling. After being rewarmed to 36°C, temperatures were controlled with antipyretic (chronologically divided into groups A-C with 47, 46, and 46 patients, respectively) or endovascular (group D, 38 patients) cooling. Overall, 177 patients (median age, 62 [52-68] years; 94 [53.1%] women; onset-to-arrival time, 36 minutes [28-50]) were included. The median Glasgow Coma Scale (GCS) score upon admission was 4 (3-6). Median core body temperature was 36 (35.3-36.6)°C on arrival, 34.6 (34.0-35.3)°C on entering the operating room, 33.8 (33.4-34.3)°C upon starting the microsurgical or interventional radiology procedure, and 33.7 (33.3-34.2)°C upon admission to the intensive care unit. There were no significant differences in age, sex, GCS score, pupillary findings, location of bleeding sources, or treatment methods. There were 69 (39.0%) overall favorable outcomes (modified Rankin Scale score of 0-3) at 6 months and 11 (23.4%), 18 (39.1%), 17 (37.0%), and 23 (60.5%) in groups A-D, respectively (p = 0.0065). The outcomes of patients with WFNS grade V SAH improved over time. Herein, we report our experience using BHT for severe SAH through a narrative review.

Mild (34 °C) versus moderate hypothermia (24 °C) in a swine model of extracorporeal cardiopulmonary resuscitation

Background

The role of hypothermia in post-arrest neuroprotection is controversial. Animal studies suggest potential benefits with lower temperatures, but high-fidelity ECPR models evaluating temperatures below 30 °C are lacking.

Objectives

To determine whether rapid cooling to 24 °C initiated upon reperfusion reduces brain injury compared to 34 °C in a swine model of ECPR.

Methods

Twenty-four female pigs had electrically induced VF and mechanical CPR for 30 min. Animals were cannulated for VA-ECMO and cooled to either 34 °C for 4 h (n = 8), 24 °C for 1 h with rewarming to 34 °C over 3 h (n = 7), or 24 °C for 4 h without rewarming (n = 9). Cooling was initiated upon VA-ECMO reperfusion by circulating ice water through the oxygenator. Brain temperature and cerebral and systemic hemodynamics were continuously monitored. After four hours on VA-ECMO, brain tissue was obtained for examination.

Results

Target brain temperature was achieved within 30 min of reperfusion (p = 0.74). Carotid blood flow was higher in the 24 °C without rewarming group throughout the VA-ECMO period compared to 34 °C and 24 °C with rewarming (p < 0.001). Vasopressin requirement was higher in animals treated with 24 °C without rewarming (p = 0.07). Compared to 34 °C, animals treated with 24 °C with rewarming were less coagulopathic and had less immunohistochemistry-detected neurologic injury. There were no differences in global brain injury score.

Conclusions

Despite improvement in carotid blood flow and immunohistochemistry detected neurologic injury, reperfusion at 24 °C with or without rewarming did not reduce early global brain injury compared to 34 °C in a swine model of ECPR.

Hypothermia After Cardiac Arrest in Large Animals (HACA-LA): Study protocol of a randomized controlled experimental trial

Background

Induced hypothermia post-cardiac arrest is neuroprotective in animal experiments, but few high-quality studies have been performed in larger animals with human-like brains. The neuroprotective effect of postischemic hypothermia has recently been questioned in human trials. Our aim is to investigate whether hypothermia post-cardiac arrest confers a benefit compared to normothermia in large adult animals. Our hypothesis is that induced hypothermia post cardiac arrest is neuroprotective and that the effect diminishes when delayed two hours.

Methods

Adult female pigs were anesthetized, mechanically ventilated and kept at baseline parameters including normothermia (38 °C). All animals were subjected to ten minutes of cardiac arrest (no-flow) by induced ventricular fibrillation, followed by four minutes of cardiopulmonary resuscitation with mechanical compressions, prior to the first countershock. Animals with sustained return of spontaneous circulation (systolic blood pressure >60 mmHg for ten minutes) within fifteen minutes from start of life support were included and randomized to three groups; immediate or delayed (2 h) intravenous cooling, both targeting 33 °C, or intravenously controlled normothermia (38 °C). Temperature control was applied for thirty hours including cooling time, temperature at target and controlled rewarming (0.5 °C/h). Animals were extubated and kept alive for seven days. The primary outcome measure is histological brain injury on day seven. Secondary outcomes include neurological and neurocognitive recovery, and the trajectory of biomarkers of brain injury.

Conclusion

High-quality animal experiments in clinically relevant large animal models are necessary to close the gap of knowledge regarding neuroprotective effects of induced hypothermia after cardiac arrest.Trial registration:Preclinicaltrials.eu (PCTE0000272), published 2021-11-03.

Targeted Temperature Management After Cardiac Arrest in COVID-19 Patients

There is a paucity of evidence regarding the utility of targeted temperature management (TTM) in COVID-19 patients who suffer cardiac arrest. This systematic review and meta-analysis aimed to use the available data of how temperature predicts outcomes in COVID-19 patients and the association between active cooling and outcomes in non-COVID-19 cardiac arrest patients to give recommendations for the utility of TTM in COVID-19 survivors of cardiac arrest. The PubMed, Embase, and Web of Science databases were queried in August 2022 for two separate searches: (1) temperature as a predictor of clinical outcomes in COVID-19 and (2) active cooling after return of spontaneous circulation (ROSC) in non-COVID-19. Forest plots were generated to summarize the results. Of the 4209 abstracts screened, none assessed the target population of TTM in COVID-19 victims of cardiac arrest. One retrospective cohort study evaluated hyperthermia in critically ill COVID-19 patients, two retrospective cohort studies evaluated hypothermia in septic COVID-19 patients, and 20 randomized controlled trials evaluated active cooling in non-COVID-19 patients after ROSC. Risk of death was higher in COVID-19 patients who presented with hyperthermia (risk ratio [RR] = 1.87) or hypothermia (RR = 1.77; p < 0.001). In non-COVID-19 victims of cardiac arrest, there was no significant difference in mortality (RR = 0.94; p = 0.098) or favorable neurological outcome (RR = 1.05; p = 0.41) with active cooling after ROSC. Further studies are needed to evaluate TTM in COVID-19 victims of cardiac arrest. However, given the available evidence that hyperthermia or hypothermia in COVID-19 patients is associated with increased mortality as well as our findings suggesting limited utility for active cooling in non-COVID-19 cardiac arrest patients, we posit that TTM to normothermia (core body temperature ∼37°C) would most likely be optimal for the best outcomes in COVID-19 survivors of cardiac arrest.

Clinical Insights and Future Directions in Hypothermia for Severe Traumatic Brain Injury: A Narrative Review

Fever control is essential in patients with severe traumatic brain injury (TBI). The efficacy of therapeutic hypothermia (TH) in severe TBI has been investigated over the last few decades; however, in contrast to experimental studies showing benefits, no evidence of efficacy has been demonstrated in clinical practice. In this review, the mechanisms and history of hypothermia were briefly outlined, while the results of major randomized controlled trials (RCTs) and meta-analyses investigating TH for adult TBI were introduced and discussed. The retrieved meta-analyses showed conflicting results, with a limited number of studies indicating the benefits of TH. Some studies have shown the benefits of long-term TH compared with short-term TH. Although TH is effective at lowering elevated intracranial pressure (ICP), reduced ICP does not lead to favorable outcomes. Low-quality RCTs overestimated the benefits of TH, while high-quality RCTs showed no difference or worse outcomes with TH. RCTs assessing standardized TH quality demonstrated the benefits of TH. As TBI has heterogeneous and complicated pathologies, applying a uniform treatment may not be ideal. A meta-analysis of young patients who underwent early cooling and hematoma removal showed better TH results. TH should not be abandoned, and its optimal usage should be advocated on an individual basis.

Protein Requirement Changes According to the Treatment Application in Neurocritical Patients

OBJECTIVE

Exploring protein requirements for critically ill patients has become prominent. On the other hand, considering the significant impact of coma therapy and targeted temperature management (TTM) on the brain as well as systemic metabolisms, protein requirements may plausibly be changed by treatment application. However, there is currently no research on protein requirements following the application of these treatments. Therefore, the aim of this study is to elucidate changes in patients' protein requirements during the application of TTM and coma therapy.

METHODS

This study is a retrospective analysis of prospectively collected data from March 2019 to May 2022. Among the patients admitted to the intensive care unit, those receiving coma therapy and TTM were included. The patient's treatment period was divided into two phases (phase 1, application and maintenance of coma therapy and TTM; phase 2, tapering and cessation of treatment). In assessing protein requirements, the urine urea nitrogen (UUN) method was employed to estimate the nitrogen balance, offering insight into protein utilization within the body. The patient's protein requirement for each phase was defined as the amount of protein required to achieve a nitrogen balance within ±5, based on the 24-hour collection of UUN. Changes in protein requirements between phases were analyzed.

RESULTS

Out of 195 patients, 107 patients with a total of 214 UUN values were included. The mean protein requirement for the entire treatment period was 1.84±0.62 g/kg/day, which is higher than the generally recommended protein supply of 1.2 g/kg/day. As the treatment was tapered, there was a statistically significant increase in the protein requirement from 1.49±0.42 to 2.18±0.60 in phase 2 (p<0.001).

CONCLUSION

Our study revealed a total average protein requirement of 1.84±0.62 g during the treatment period, which falls within the upper range of the preexisting guidelines. Nevertheless, a notable deviation emerged when analyzing the treatment application period separately. Hence, it is recommended to incorporate considerations for the type and timing of treatment, extending beyond the current guideline, which solely accounts for the severity by disease.

Computational insights into survival durations and prehospital interventions in accidental cold-water immersion: A comprehensive analysis of fresh and saltwater temperatures

This study examines the complex relationship between scenarios of cold-water immersion, survival durations, and prehospital interventions. It utilizes computational modeling methods to shed light on how different water temperatures affect individuals facing accidental cold-water immersion incidents. The analysis reveals significant variations in survival times based on water temperature. For example, subjects immersed in water at temperatures of 5 °C, 2 °C, and 0 °C had average survival times of 136, 113, and 100 min, respectively, under stable conditions. In flowing water at the same temperatures, survival times decreased to 119, 92, and 81 min, indicating the impact of water movement on cooling rates and survival durations. Likewise, individuals immersed in saltwater at temperatures of 5 °C, 2 °C, 0 °C, and -2 °C showed average survival times of 111, 88, 80, and 66 min, respectively, in static conditions. In flowing saltwater at the same temperatures, survival times decreased to 98, 74, 68, and 57 min, highlighting the influence of water flow on cooling rates and survival durations. A comparison between immersion in pure water and saltwater at 2 °C revealed survival times of 113 and 88 min under stable conditions and 92 and 74 min under dynamic conditions, emphasizing the role of water composition in survival outcomes. The study also challenges the notion that the demise of the Titanic's passengers and crew resulted from hypothermia, asserting instead that severe thermal shock was the primary cause. These numerical findings underscore the importance of considering water temperature, flow dynamics, and prompt medical responses in cold-water emergencies to enhance survival prospects. The study identifies water within the range of 41-43 °C as the most effective active external rewarming fluid for critical hypothermal conditions. By quantifying the impact of these variables on survival times, the study provides data-driven recommendations to improve emergency protocols and outcomes for individuals facing cold-water immersion incidents.

Urine Proteomic Signatures of Mild Hypothermia Treatment in Cerebral Ischemia-Reperfusion Injury in Rats

Mild hypothermia (MH) is an effective measure to alleviate cerebral ischemia-reperfusion (I/R) injury. However, the underlying biological mechanisms remain unclear. This study set out to investigate dynamic changes in urinary proteome due to MH in rats with cerebral I/R injury and explore the neuroprotective mechanisms of MH. A Pulsinelli's four-vessel occlusion (4-VO) rat model was used to mimic global cerebral I/R injury. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to profile the urinary proteome of rats with/without MH (32 °C) treatment after I/R injury. Representative differentially expressed proteins (DEPs) associated with MH were validated by western blotting in hippocampus. A total of 597 urinary proteins were identified, among which 119 demonstrated significant changes associated with MH. Gene Ontology (GO) annotation of the DEPs revealed that MH significantly enriched in endopeptidase activity, inflammatory response, aging, response to oxidative stress and reactive oxygen species, blood coagulation, and cell adhesion. Notably, changes in 12 DEPs were significantly reversed by MH treatment. Among them, 8 differential urinary proteins were previously reported to be closely associated with brain disease, including NP, FZD1, B2M, EPCR, ATRN, MB, CA1and VPS4A. Two representative proteins (FZD1, B2M) were further validated by western blotting in the hippocampus and the results were shown to be consistent with urinary proteomic analysis. Overall, this study strengthens the idea that urinary proteome can sensitively reflect pathophysiological changes in the brain, and appears to be the first study to explore the neuroprotective effects of MH by urinary proteomic analysis. FZD1 and B2M may be involved in the most fundamental molecular biological mechanisms of MH neuroprotection.

Temperature Control in Acute Brain Injury: An Update

Temperature control in severe acute brain injury (SABI) is a key component of acute management. This manuscript delves into the complex role of temperature management in SABI, encompassing conditions like traumatic brain injury (TBI), acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), aneurysmal subarachnoid hemorrhage (aSAH), and hypoxemic/ischemic brain injury following cardiac arrest. Fever is a common complication in SABI and is linked to worse neurological outcomes due to increased inflammatory responses and intracranial pressure (ICP). Temperature management, particularly hypothermic temperature control (HTC), appears to mitigate these adverse effects primarily by reducing cerebral metabolic demand and dampening inflammatory pathways. However, the effectiveness of HTC varies across different SABI conditions. In the context of post-cardiac arrest, the impact of HTC on neurological outcomes has shown inconsistent results. In cases of TBI, HTC seems promising for reducing ICP, but its influence on long-term outcomes remains uncertain. For AIS, clinical trials have yet to conclusively demonstrate the benefits of HTC, despite encouraging preclinical evidence. This variability in efficacy is also observed in ICH, aSAH, bacterial meningitis, and status epilepticus. In pediatric and neonatal populations, while HTC shows significant benefits in hypoxic-ischemic encephalopathy, its effectiveness in other brain injuries is mixed. Although the theoretical basis for employing temperature control, especially HTC, is strong, the clinical outcomes differ among various SABI subtypes. The current consensus indicates that fever prevention is beneficial across the board, but the application and effectiveness of HTC are more nuanced, underscoring the need for further research to establish optimal temperature management strategies. Here we provide an overview of the clinical evidence surrounding the use of temperature control in various types of SABI.

Temperature management in acute brain injury: A narrative review

Temperature management has been used in patients with acute brain injury resulting from different conditions, such as post-cardiac arrest hypoxic-ischaemic insult, acute ischaemic stroke, and severe traumatic brain injury. However, current evidence offers inconsistent and often contradictory results regarding the clinical benefit of this therapeutic strategy on mortality and functional outcomes. Current guidelines have focused mainly on active prevention and treatment of fever, while therapeutic hypothermia (TH) has fallen into disuse, although doubts persist as to its effectiveness according to the method of application and appropriate patient selection. This narrative review presents the most relevant clinical evidence on the effects of TH in patients with acute neurological damage, and the pathophysiological concepts supporting its use.

Safety and effectiveness of the sutureless integrated stented graft prosthesis in an animal model

Background

Prolonged circulatory arrest time is an independent risk factor for postoperative adverse events of type A aortic dissection (TAAD) surgery. Further reduction of the circulatory arrest time is essential to improve surgical outcomes. This study aimed to evaluate the safety and effectiveness of the novel Sutureless Integrated Stented (SIS) graft prosthesis in an animal experiment.

Materials and methods

Straight type of the SIS graft prosthesis was implanted into the descending aorta of 10 adult male sheep, and the use of the device was scored on a scale of 1-10. Aortic digital subtraction angiography (DSA) was performed at 4, 14, and 26 weeks to investigate the prostheses. After 26 weeks, the animals were sacrificed for histological analysis.

Results

The immediate success rate of the surgery was 100 %, and the overall mean score of the use of the device was 9.65 ± 0.99. Three animals died from non-device-related causes during follow-up. Aortic DSA showed filling defects in 5 animals. Histological analysis revealed that all prostheses were intact. Except for 2 early deaths, the other 8 prostheses were endothelialized with mild inflammation, foreign body reactions, and intimal fibrosis. The mean cross-sectional area of the sutureless region was reduced by 26.4 % (range, 1.3-39.1 %).

Conclusions

The safety and effectiveness of the novel SIS graft prosthesis were acceptable, and the delivery system exhibited a promising performance. Using the SIS graft prosthesis in TAAD surgery was expected to simplify the procedures and shorten the circulatory arrest time. Further large-scale clinical trials are required to verify these findings.

The efficacy of therapeutic hypothermia in patients with poor-grade aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

BACKGROUND

This study evaluates the effectiveness of Therapeutic Hypothermia (TH) in treating poor-grade aneurysmal subarachnoid hemorrhage (SAH), focusing on functional outcomes, mortality, and complications such as vasospasm, delayed cerebral ischemia (DCI), and hydrocephalus.

METHODS

Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, a comprehensive literature search was conducted across multiple databases, including Medline, Embase, and Cochrane Central, up to November 2023. Nine studies involving 368 patients were selected based on eligibility criteria focusing on TH in poor-grade SAH patients. Data extraction, bias assessment, and evidence certainty were systematically performed.

RESULTS

The primary analysis of unfavorable outcomes in 271 participants showed no significant difference between the TH and standard care groups (risk ratio [RR], 0.87). However, a significant reduction in vasospasm was observed in the TH group (RR, 0.63) among 174 participants. No significant differences were found in DCI, hydrocephalus, and mortality rates in the respective participant groups.

CONCLUSIONS

TH did not significantly improve primary unfavorable outcomes in poor-grade SAH patients. However, the reduction in vasospasm rates indicates potential specific benefits. The absence of significant findings in other secondary outcomes and mortality highlights the need for further research to better understand TH's role in treating this patient population.

Therapeutic management of ischemic stroke

Stroke is the third leading cause of years lost due to disability and the second-largest cause of mortality worldwide. Most occurrences of stroke are brought on by the sudden occlusion of an artery (ischemic stroke), but sometimes they are brought on by bleeding into brain tissue after a blood vessel has ruptured (hemorrhagic stroke). Alteplase is the only therapy the American Food and Drug Administration has approved for ischemic stroke under the thrombolysis category. Current views as well as relevant clinical research on the diagnosis, assessment, and management of stroke are reviewed to suggest appropriate treatment strategies. We searched PubMed and Google Scholar for the available therapeutic regimes in the past, present, and future. With the advent of endovascular therapy in 2015 and intravenous thrombolysis in 1995, the therapeutic options for ischemic stroke have expanded significantly. A novel approach such as vagus nerve stimulation could be life-changing for many stroke patients. Therapeutic hypothermia, the process of cooling the body or brain to preserve organ integrity, is one of the most potent neuroprotectants in both clinical and preclinical contexts. The rapid intervention has been linked to more favorable clinical results. This study focuses on the pathogenesis of stroke, as well as its recent advancements, future prospects, and potential therapeutic targets in stroke therapy.

Review of Temperature Management in Traumatic Brain Injuries

Therapeutic hypothermia (TH) for severe traumatic brain injury has seen restricted application due to the outcomes of randomized controlled trials (RCTs) conducted since 2000. In contrast with earlier RCTs, recent trials have implemented active normothermia management in control groups, ensuring comparable intensities of non-temperature-related therapeutic interventions, such as neurointensive care. This change in approach may be a contributing factor to the inability to establish the efficacy of TH. Currently, an active temperature management method using temperature control devices is termed "targeted temperature management (TTM)". One of the goals of TTM for severe traumatic brain injury is the regulation of increased intracranial pressure, employing TTM as a methodology for intracranial pressure management. Additionally, fever in traumatic brain injury has been acknowledged as contributing to poor prognosis, underscoring the importance of proactively preventing fever. TTM is also employed for the preemptive prevention of fever in severe traumatic brain injury. As an integral component of current neurointensive care, it is crucial to precisely delineate the targets of TTM and to potentially apply them in the treatment of severe traumatic brain injury.

Ex vivo kidney machine perfusion: meta-analysis of randomized clinical trials

BACKGROUND

Machine perfusion is an organ preservation strategy used to improve function over simple storage in a cold environment. This article presents an updated systematic review and meta-analysis of machine perfusion in deceased donor kidneys.

METHODS

RCTs from November 2018 to July 2023 comparing machine perfusion versus static cold storage in kidney transplantation were evaluated for systematic review. The primary outcome in meta-analysis was delayed graft function.

RESULTS

A total 19 studies were included, and 16 comparing hypothermic machine perfusion with static cold storage were analysed. The risk of delayed graft function was lower with hypothermic machine perfusion (risk ratio (RR) 0.77, 95% c.i. 0.69 to 0.86), even in kidneys after circulatory death (RR 0.78, 0.68 to 0.90) or brain death (RR 0.73, 0.63 to 0.84). Full hypothermic machine perfusion decreased the risk of delayed graft function (RR 0.69, 0.60 to 0.79), whereas partial hypothermic machine perfusion did not (RR 0.92, 0.69 to 1.22). Normothermic machine perfusion or short-term oxygenated hypothermic machine perfusion preservation after static cold storage was equivalent to static cold storage in terms of delayed graft function and 1-year graft survival.

CONCLUSION

Hypothermic machine perfusion reduces delayed graft function risks and normothermic approaches show promise.

Early enteral nutrition in patients with out-of-hospital cardiac arrest under target temperature management was associated with a lower 7-day bacteremia rate: A post-hoc analysis of a retrospective cohort study

INTRODUCTION

Early enteral nutrition (EN) is a nutritional strategy for reducing the incidence of in-hospital infections. However, the benefits of early EN, under targeted temperature management (TTM) in patients with out-of-hospital cardiac arrest (OHCA), remain unclear. We aimed to evaluate the effect of early EN on the infective complications of OHCA patients who underwent TTM.

METHODS

We retrospectively searched the clinical databases of two adult emergency tertiary referral hospitals in southern Taiwan and identified patients admitted for OHCA who underwent TTM between 2017 and 2022. The 85 enrolled patients were divided into two groups based on timing: early EN (EN within 48 h of admission) and delayed EN (EN > 48 h after admission). Clinical outcomes of 7-day infective complications between the two groups were analyzed.

RESULTS

Early EN was provided to 57 (67 %) of 85 patients and delayed EN was provided to the remaining 28 (33 %) patients. No significant differences in baseline patient characteristics were observed between the two groups. In addition, no differences in clinical outcomes were observed, except that the early EN group had a lower 7-day bacteremia rate (5.3 % vs. 26.9 %, p = 0.013). Gram-negative bacteria were the major pathogen among the 7-day infective complications.

CONCLUSION

In OHCA patients treated with TTM, early EN was associated with a lower 7-day bacteremia rate. Furthermore, the application of early EN in this population was well tolerated without significant adverse events.

Case report: Anesthetic management for removal of tumor thrombus in the inferior vena cava and pulmonary artery in renal cell carcinoma

Anesthetic management of patients with renal cell carcinoma with tumor thrombus in the inferior vena cava (IVC) is challenging. This paper reports the experience of anesthesia management in a patient with advanced renal cell carcinoma with thrombus accumulation in the IVC, right atrium, and pulmonary artery who underwent radical nephrectomy and tumor thrombus removal assisted by cardiopulmonary bypass. The emboli, measuring approximately 3 × 6 cm in the left inferior pulmonary artery and 4 × 13 cm in the right main pulmonary artery, were removed completely. During incision of the IVC under systemic heparinization, significant blood loss occurred in the surgical field. The surgery took 724 min, and cardiopulmonary bypass took 396 min. Intraoperative blood loss was 22,000 ml. The patient was extubated 39 hours after surgery and stayed in intensive care unit for 3 days. At 1 year follow-up, the patient was in good health and leading a normal life.

Therapeutic Hypothermia in Treating Glioblastoma: A Review

Glioblastoma (GBM) is the most commonly occurring of all malignant central nervous system (CNS) tumors in adults. Considering the low median survival of only ∼15 months and poor prognosis in GBM patients, despite surgical resection with adjuvant radiation and chemotherapy, it is vital to seek brand new and innovative treatment in combination with already existing methods. Hypothermia participates in many metabolic pathways, inflammatory responses, and apoptotic processes, while also promoting the integrity of neurons. Following the successful application of therapeutic hypothermia across a spectrum of disorders such as traumatic CNS injury, cardiac arrest, and epilepsy, several clinical trials have set to evaluate the potency of hypothermia in treating a variety of cancers, including breast and ovaries cancer. In regard to primary neoplasms and more specifically, GBM, hypothermia has recently shown promising results as an auxiliary treatment, reinforcing chemotherapy's efficacy. In this review, we discuss the recent advances in utilizing hypothermia as treatment for GBM and other cancers.

Metabolic Manipulation and Therapeutic Hypothermia

Hypothermia has multiple physiological effects, including decreasing metabolic rate and oxygen consumption (VO2). There are few human data about the magnitude of change in VO2 with decreases in core temperature. We aimed to quantify to magnitude of reduction in resting VO2 as we reduced core temperature in lightly sedated healthy individuals. After informed consent and physical screening, we cooled participants by rapidly infusing 20 mL/kg of cold (4°C) saline intravenously and placing surface cooling pads on the torso. We attempted to suppress shivering using a 1 mcg/kg intravenous bolus of dexmedetomidine followed by titrated infusion at 1.0 to 1.5 μg/(kg·h). We measured resting metabolic rate VO2 through indirect calorimetry at baseline (37°C) and at 36°C, 35°C, 34°C, and 33°C. Nine participants had mean age 30 (standard deviation 10) years and 7 (78%) were male. Baseline VO2 was 3.36 mL/(kg·min) (interquartile range 2.98-3.76) mL/(kg·min). VO2 was associated with core temperature and declined with each degree decrease in core temperature, unless shivering occurred. Over the entire range from 37°C to 33°C, median VO2 declined 0.7 mL/(kg·min) (20.8%) in the absence of shivering. The largest average decrease in VO2 per degree Celsius was by 0.46 mL/(kg·min) (13.7%) and occurred between 37°C and 36°C in the absence of shivering. After a participant developed shivering, core body temperature did not decrease further, and VO2 increased. In lightly sedated humans, metabolic rate decreases around 5.2% for each 1°C decrease in core temperature from 37°C to 33°C. Because the largest decrease in metabolic rate occurs between 37°C and 36°C, subclinical shivering or other homeostatic reflexes may be present at lower temperatures.

Emergent Management of Severe Hypothermia, Acidemia, and Coagulopathy in Operative Penetrating Ballistic Cranial Trauma

Hypothermia in a trauma patient has been associated with increased morbidity and mortality and is more frequently seen in those sustaining traumatic brain injuries (TBIs). Acidosis is an important consequence of hypothermia that leads to derangements across the spectrum of the coagulation cascade. Here, we present a case of a 31-year-old male presented after suffering a right parietal penetrating ballistic injury with an associated subdural hematoma and 7 mm midline shift requiring decompressive craniectomy and external ventricular drain (EVD) placement in the setting of severe hypothermia (28°C) and acidosis (pH 7.12). With aggressive rewarming intraoperatively, the use of full-body forced-air warming, warmed IV fluids, and increasing the ambient room temperature, the patient's acidosis and hypothermia improved to pH 7.20 and 34°C. Despite these aggressive attempts to rewarm the patient, he developed coagulopathy in the setting of concurrent hypothermia and acidosis. This case highlights the importance of prompt reversal of hypothermia due to its potentially fatal effects, particularly in the setting of severe TBIs. We discuss the critical aspects of surgical management of the injury and anesthetic management of hypothermia, acidosis, and coagulopathy perioperatively.

Clinical outcomes of mild versus moderate hypothermic circulatory arrest with antegrade cerebral perfusion in adult aortic arch surgery: A systematic review and meta-analysis

OBJECTIVES

In adult aortic arch surgery, moderate hypothermic circulatory arrest (HCA) with selective antegrade cerebral perfusion (SACP) (MoHACP) is widely used, but the application of mild HCA with SACP (MiHACP) is still controversial. This meta-analysis aimed to compare clinical outcomes using MiHACP or MoHACP.

METHODS

Studies comparing outcomes of MiHACP or MoHACP in adult aortic arch surgery were searched from four databases from inception through April 2022. Primary outcomes were postoperative permanent neurological deficit (PND), temporary neurological deficit (TND), and mortality. Secondary outcomes included other common complications. Meta-analysis was conducted using a random-effects model in all cases.

RESULTS

Eleven comparative studies were included, with 1555 patients in MiHACP group and 1499 patients in MoHACP group, and the mean HCA temperature were 29.4°C and 24.8°C, respectively. Postoperative PND, TND, mortality, paraplegia, dialysis, tracheotomy, reexploration for bleeding, and chest tube drainage volume were comparable in the two groups (p > 0.05). Ventilator time, intensive care unit and in-hospital length of stay were shorter in MiHACP group (p < 0.05). Outcomes were also comparable or had some benefits in MiHACP group when subgroup analyses were conducted according to hemiarch or total arch replacement, unilateral or bilateral SACP, HCA time, emergency aortic dissection surgery, and concomitant procedure.

CONCLUSION

The present meta-analysis showed acceptability of MiHACP in adult aortic arch surgery. Results need to be taken with caution as moderate risk of bias and very low quality of evidence were observed in this meta-analysis. Randomized controlled trials are needed for further analysis.

Extracorporeal membrane oxygenation circuits in parallel for refractory hypoxemia in patients with COVID-19

OBJECTIVES

Refractory hypoxemia can occur in patients with acute respiratory distress syndrome from COVID-19 despite support with venovenous (VV) extracorporeal membrane oxygenation (ECMO). Parallel ECMO circuits can be used to increase physiologic support. We report our clinical experience using ECMO circuits in parallel for select patients with persistent severe hypoxemia despite the use of a single ECMO circuit.

METHODS

We performed a retrospective cohort study of all patients with COVID-19-related acute respiratory distress syndrome who received VV-ECMO with an additional circuit in parallel at Vanderbilt University Medical Center between March 1, 2020, and March 1, 2022. We report demographic characteristics and clinical characteristics including ECMO settings, mechanical ventilator settings, use of adjunctive therapies, and arterial blood gas results after initial cannulation, before and after receipt of a second ECMO circuit in parallel, and before removal of the circuit in parallel, and outcomes.

RESULTS

Of 84 patients with COVID-19 who received VV-ECMO during the study period, 22 patients (26.2%) received a circuit in parallel. The median duration of ECMO was 40.0 days (interquartile range, 31.6-53.1 days), of which 19.0 days (interquartile range, 13.0-33.0 days) were spent with a circuit in parallel. Of the 22 patients who received a circuit in parallel, 16 (72.7%) survived to hospital discharge and 6 (27.3%) died before discharge.

CONCLUSIONS

In select patients, the additional use of an ECMO circuit in parallel can increase ECMO blood flow and improve oxygenation while allowing for lung-protective mechanical ventilation and excellent outcomes.

Effect of prewarmed crystalloid fluids and an in-line fluid warming device on fluid outflow temperatures at ambient temperatures of 21-22°C and 3.5°C

Equine veterinarians frequently treat patients in non-climate-controlled (i.e., hospitalized) settings. In colder environments, intravenous (IV) fluid administration can contribute to patient hypothermia. The objective of this study was to evaluate three IV fluid warming mechanisms to determine their effect on fluid outflow temperatures at ambient temperatures of 21-22°C and 3.5°C. In this study, fluid outflow temperatures were measured using three warming mechanisms: (1) pre-warmed fluids at 42°C, (2) an in-line warming device placed 163 cm away from the Luer-lock fluid line adaptor (location 1) on the fluid line, and (3) an in-line warming device placed 88 cm away from the Luer-lock fluid line adaptor (location 2) on the fluid line. These warming mechanisms were compared to outflow temperatures measured using no warming mechanism at ambient temperatures of 21-22°C and 3.5°C with flow rates of ∼12 L/hour (gravity flow bolus) and 999 mL/hour. All outflow temperatures were measured with a thermistor. At ∼12L/hour, the use of pre-warmed fluids increased outflow temperatures at both ambient temperatures of 21-22°C and 3.5°C ambient temperatures and an in-line warming device placed at location 1 significantly increased outflow temperatures in 3.5°C ambient temperatures. At 999 mL/hour, use of pre-warmed fluids or an in-line warming device, placed at either location, increased outflow temperatures at ambient temperatures of 21°C or 3.5°C.

Targeted therapeutic hypothermia protects against noise induced hearing loss

Introduction

Exposure to occupational or recreational loud noise activates multiple biological regulatory circuits and damages the cochlea, causing permanent changes in hearing sensitivity. Currently, no effective clinical therapy is available for the treatment or mitigation of noise-induced hearing loss (NIHL). Here, we describe an application of localized and non-invasive therapeutic hypothermia and targeted temperature management of the inner ear to prevent NIHL.

Methods

We developed a custom-designed cooling neck collar to reduce the temperature of the inner ear by 3-4°C post-injury to deliver mild therapeutic hypothermia.

Results

This localized and non-invasive therapeutic hypothermia successfully mitigated NIHL in rats. Our results show that mild hypothermia can be applied quickly and safely to the inner ear following noise exposure. We show that localized hypothermia after NIHL preserves residual hearing and rescues noise-induced synaptopathy over a period of months.

Discussion

This study establishes a minimally-invasive therapeutic paradigm with a high potential for rapid translation to the clinic for long-term preservation of hearing health.

Primary amebic meningoencephalitis: a review of Naegleria fowleri and analysis of successfully treated cases

Primary amebic meningoencephalitis (PAM) is a necrotizing and hemorrhagic inflammation of the brain and meninges caused by Naegleria fowleri, a free-living thermophilic ameba of freshwater systems. PAM remains a neglected disease that disproportionately affects children in tropical and subtropical climates, with an estimated mortality rate of 95-98%. Due to anthropogenic climate change, the average temperature in the USA has increased by 0.72 to 1.06 °C in the last century, promoting the poleward spread of N. fowleri. PAM is often misdiagnosed as bacterial meningitis or viral encephalitis, which shortens the window for potentially life-saving treatment. Diagnosis relies on the patient's history of freshwater exposure and the physician's high index of suspicion, supported by cerebrospinal fluid studies. While no experimental trials have been conducted to assess the relative efficacy of treatment regimens, anti-amebic therapy with adjunctive neuroprotection is standard treatment in the USA. We performed a literature review and identified five patients from North America between 1962 and 2022 who survived PAM with various degrees of sequelae.

Association of body temperature and mortality in critically ill patients: an observational study using two large databases

BACKGROUND

Body temperature (BT) is routinely measured and can be controlled in critical care settings. BT can impact patient outcome, but the relationship between BT and mortality has not been well-established.

METHODS

A retrospective cohort study was conducted based on the MIMIC-IV (N = 43,537) and eICU (N = 75,184) datasets. The primary outcome and exposure variables were hospital mortality and first 48-h median BT, respectively. Generalized additive models were used to model the associations between exposures and outcomes, while adjusting for patient age, sex, APS-III, SOFA, and Charlson comorbidity scores, temperature gap, as well as ventilation, vasopressor, steroids, and dialysis usage. We conducted subgroup analysis according to ICU setting, diagnoses, and demographics.

RESULTS

Optimal BT was 37 °C for the general ICU and subgroup populations. A 10% increase in the proportion of time that BT was within the 36-38 °C range was associated with reduced hospital mortality risk in both MIMIC-IV (OR 0.91; 95% CI 0.90-0.93) and eICU (OR 0.86; 95% CI 0.85-0.87). On the other hand, a 10% increase in the proportion of time when BT < 36 °C was associated with increased mortality risk in both MIMIC-IV (OR 1.08; 95% CI 1.06-1.10) and eICU (OR 1.18; 95% CI 1.16-1.19). Similarly, a 10% increase in the proportion of time when BT > 38 °C was associated with increased mortality risk in both MIMIC-IV (OR 1.09; 95% CI 1.07-1.12) and eICU (OR 1.09; 95% CI 1.08-1.11). All patient subgroups tested consistently showed an optimal temperature within the 36-38 °C range.

CONCLUSIONS

A BT of 37 °C is associated with the lowest mortality risk among ICU patients. Further studies to explore the causal relationship between the optimal BT and mortality should be conducted and may help with establishing guidelines for active BT management in critical care settings.

Antipyretic Use in Noncritically Ill Patients With Fever: A Review

Antipyretics are one of the most frequently used agents in medicine. Numerous pharmacological agents, such as acetaminophen, non-steroidal anti-inflammatory agents (NSAIDs), salicylates, and selective cyclooxygenase 2 (COX-2) inhibitors, and nonpharmacological treatment modalities, such as tepid sponging and cooling blankets, are available for temperature reduction. There is a scarcity of definitive clinical guidelines on the choice of various agents in noncritically ill febrile patients. Our review examined the various modalities available for antipyresis and compared their safety and efficacy. The rationale for the choice of a particular pharmacological agent and route of administration were scrutinized. Our review also envisaged the perceived beneficial effects of antipyretics against the harmful side effects, including the evaluation of morbidity or mortality advantage conferred by antipyretics. The various toxicities associated with these agents were also highlighted.

Hypothermia: Beyond the Narrative Review-The Point of View of Emergency Physicians and Medico-Legal Considerations

Hypothermia is a widespread condition all over the world, with a high risk of mortality in pre-hospital and in-hospital settings when it is not promptly and adequately treated. In this review, we aim to describe the main specificities of the diagnosis and treatment of hypothermia through consideration of the physiological changes that occur in hypothermic patients. Hypothermia can occur due to unfavorable environmental conditions as well as internal causes, such as pathological states that result in reduced heat production, increased heat loss or ineffectiveness of the thermal regulation system. The consequences of hypothermia affect several systems in the body-the cardiovascular system, the central and peripheral nervous systems, the respiratory system, the endocrine system and the gastrointestinal system-but also kidney function, electrolyte balance and coagulation. Once hypothermia is recognized, prompt treatment, focused on restoring body temperature and supporting vital functions, is fundamental in order to avert preventable death. It is important to also denote the fact that CPR has specificities related to the unique profile of hypothermic patients.

The Effect of Targeted Temperature Management on the Metabolome Following Out-of-Hospital Cardiac Arrest

Targeted temperature management (TTM) may moderate the injury from out-of-hospital cardiac arrest. Slowing the metabolism has been a suggested effect. Nevertheless, studies have found higher lactate levels in patients cooled to 33°C compared with 36°C even days from TTM cessation. Larger studies have not been performed on the TTM's effect on the metabolome. Accordingly, to explore the effect of TTM, we used ultra-performance liquid-mass spectrometry in a substudy of 146 patients randomized in the TTM trial to either 33°C or 36°C for 24 hours and quantified 60 circulating metabolites at the time of hospital arrival (T0) and 48 hours later (T48). From T0 to T48, profound changes to the metabolome were observed: tricarboxylic acid (TCA) cycle metabolites, amino acids, uric acid, and carnitine species all decreased. TTM significantly modified these changes in nine metabolites (Benjamini-Hochberg corrected false discovery rate <0.05): branched amino acids valine and leucine levels dropped more in the 33°C arm (change [95% confidence interval]: -60.9 μM [-70.8 to -50.9] vs. -36.0 μM [-45.8 to -26.3] and -35.5 μM [-43.1 to -27.8] vs. -21.2 μM [-28.7 to -13.6], respectively), whereas the TCA metabolites including malic acid and 2-oxoglutaric acid remained higher for the first 48 hours (-7.7 μM [-9.7 to -5.7] vs. -10.4 μM [-12.4 to -8.4] and -3 μM [-4.3 to -1.7] vs. -3.7 μM [-5 to -2.3]). Prostaglandin E2 only dropped in the TTM 36°C group. The results show that TTM affects the metabolism hours after normothermia have been reached. Clinical Trial Number: NCT01020916.

Hypothermia as an Adjunctive Therapy in Cardiogenic Shock: A Systematic Review and Meta-Analysis

In the setting of out-of-hospital cardiac arrest, therapeutic hypothermia (TH) has been shown to improve clinical outcomes. However, trials showing the advantage of TH did not include patients with cardiogenic shock (CS). We performed a comprehensive literature search for studies that evaluated the efficacy and safety of adjunctive TH compared with the standard of care (SOC) in patients with CS. The primary outcome was the mortality rate (in-hospital, short-, and mid-term). The secondary outcomes were the TH-related complications, duration of Intensive Care Unit (ICU) stay, duration of mechanical ventilation (MV-days), and improvement in cardiac function. Relative risk (RR) or the standardized mean difference (SMD) and corresponding 95% confidence intervals (CIs) were calculated using the random-effects model. A total of 7 clinical studies (3 RCTs included), and 712 patients (341 in the TH group and 371 in the SOC group) were included. As compared with the SOC, TH was not associated with a statistically significant improvement in the in-hospital (RR: 0.73%, 95% CI: 0.51-1.03; p = 0.08), short-term (RR: 0.90%, 95% CI: 0.75-1.06; p = 0.21), or mid-term (RR: 0.93%, 95% CI: 0.78-1.10; p = 0.38) mortality rates. Despite the improvement in the cardiac function in the TH group (SMD: 1.08, 95% CI: 0.02-2.1; p = 0.04), the TH strategy did not significantly shorten the MV days, or the ICU stay (p-values >0.05). Finally, there was a trend toward higher risks for infection, major bleeding, and the need for blood transfusion in the TH group. According to our meta-analysis of published clinical studies, TH is not beneficial in patients with CS and has a marginal safety profile. Larger-scale RCTs are needed to further clarify our results.