Intra-arrest transnasal evaporative cooling: a randomized, prehospital, multicenter study (PRINCE: Pre-ROSC IntraNasal Cooling Effectiveness)

Temperature Control in the Era of Personalized Medicine: Knowledge Gaps, Research Priorities, and Future Directions

Hypoxic-ischemic brain injury (HIBI) is the leading cause of death and disability after cardiac arrest. To date, temperature control is the only intervention shown to improve neurologic outcomes in patients with HIBI. Despite robust preclinical evidence supporting hypothermia as neuroprotective therapy after cardiac arrest, there remains clinical equipoise regarding optimal core temperature, therapeutic window, and duration of therapy. Current guidelines recommend continuous temperature monitoring and active fever prevention for at least 72 h and additionally note insufficient evidence regarding temperature control targeting 32 °C-36 °C. However, population-based thresholds may be inadequate to support the metabolic demands of ischemic, reperfused, and dysregulated tissue. Promoting a more personalized approach with individualized targets has the potential to further improve outcomes. This review will analyze current knowledge and evidence, address research priorities, explore the components of high-quality temperature control, and define critical future steps that are needed to advance patient-centered care for cardiac arrest survivors.

COmbination of Targeted temperature management and Thrombectomy after acute Ischemic Stroke (COTTIS): a pilot study

BACKGROUND

To evaluate the feasibility and safety of a fast initiation of cooling to a target temperature of 35°C by means of transnasal cooling in patients with anterior circulation large vessel occlusion (LVO) undergoing endovascular thrombectomy (EVT).

METHODS

Patients with an LVO onset of <24 hour who had an indication for EVT were included in the study. Transnasal cooling (RhinoChill) was initiated immediately after the patient was intubated for EVT and continued until an oesophageal target temperature of 35°C was reached. Hypothermia was maintained with surface cooling for 6-hour postrecanalisation, followed by active rewarming (+0.2°C/hour). The primary outcome was defined as the time required to reach 35°C, while secondary outcomes comprised clinical, radiological and safety parameters.

RESULTS

Twenty-two patients (median age, 77 years) were included in the study (14 received additional thrombolysis, 4 additional stenting of the proximal internal carotid artery). The median time intervals were 309 min for last-seen-normal-to-groin, 58 min for door-to-cooling-initiation, 65 min for door-to-groin and 123 min for door-to-recanalisation. The target temperature of 35°C was reached within 30 min (range 13-78 min), corresponding to a cooling rate of 2.6 °C/hour. On recanalisation, 86% of the patients had a body temperature of ≤35°C. The median National Institutes of Health Stroke Scale at admission was 15 and improved to 2 by day 7, and 68% of patients had a good outcome (modified Rankin Scale 0-2) at 3 months. Postprocedure complications included asymptomatic bradycardia (32%), pneumonia (18%) and asymptomatic haemorrhagic transformation (18%).

CONCLUSION

The combined application of hypothermia and thrombectomy was found to be feasible in sedated and ventilated patents. Adverse events were comparable to those previously described for EVT in the absence of hypothermia. The effect of this procedure will next be evaluated in the randomised COmbination of Targeted temperature management and Thrombectomy after acute Ischemic Stroke-2 trial.

The design of the PRINCESS 2 trial: A randomized trial to study the impact of ultrafast hypothermia on complete neurologic recovery after out-of-hospital cardiac arrest with initial shockable rhythm

BACKGROUND

Delayed hypothermia, initiated after hospital arrival, several hours after cardiac arrest with 8-10 hours to reach the target temperature, is likely to have limited impact on overall survival. However, the effect of ultrafast hypothermia, i.e., delivered intra-arrest or immediately after return of spontaneous circulation (ROSC), on functional neurologic outcome after out-of-hospital cardiac arrest (OHCA) is unclear. In two prior trials, prehospital trans-nasal evaporative intra-arrest cooling was safe, feasible and reduced time to target temperature compared to delayed cooling. Both studies showed trends towards improved neurologic recovery in patients with shockable rhythms. The aim of the PRINCESS2-study is to assess whether cooling, initiated either intra-arrest or immediately after ROSC, followed by in-hospital hypothermia, significantly increases survival with complete neurologic recovery as compared to standard normothermia care, in OHCA patients with shockable rhythms.

METHODS/DESIGN

In this investigator-initiated, randomized, controlled trial, the emergency medical services (EMS) will randomize patients at the scene of cardiac arrest to either trans-nasal cooling within 20 minutes from EMS arrival with subsequent hypothermia at 33°C for 24 hours after hospital admission (intervention), or to standard of care with no prehospital or in-hospital cooling (control). Fever (>37,7°C) will be avoided for the first 72 hours in both groups. All patients will receive post resuscitation care and withdrawal of life support procedures according to current guidelines. Primary outcome is survival with complete neurologic recovery at 90 days, defined as modified Rankin scale (mRS) 0-1. Key secondary outcomes include survival to hospital discharge, survival at 90 days and mRS 0-3 at 90 days. In total, 1022 patients are required to detect an absolute difference of 9% (from 45 to 54%) in survival with neurologic recovery (80% power and one-sided α=0,025, β=0,2) and assuming 2,5% lost to follow-up. Recruitment starts in Q1 2024 and we expect maximum enrolment to be achieved during Q4 2024 at 20-25 European and US sites.

DISCUSSION

This trial will assess the impact of ultrafast hypothermia applied on the scene of cardiac arrest, as compared to normothermia, on 90-day survival with complete neurologic recovery in OHCA patients with initial shockable rhythm.

TRIAL REGISTRATION

NCT06025123.

Wolf Creek XVII Part 8: Neuroprotection

Introduction

Post-cardiac arrest brain injury (PCABI) is the primary determinant of clinical outcomes for patients who achieve return of spontaneous circulation after cardiac arrest (CA). There are limited neuroprotective therapies available to mitigate the acute pathophysiology of PCABI.

Methods

Neuroprotection was one of six focus topics for the Wolf Creek XVII Conference held on June 14-17, 2023 in Ann Arbor, Michigan, USA. Conference invitees included international thought leaders and scientists in the field of CA resuscitation from academia and industry. Participants submitted via online survey knowledge gaps, barriers to translation, and research priorities for each focus topic. Expert panels used the survey results and their own perspectives and insights to create and present a preliminary unranked list for each category that was debated, revised and ranked by all attendees to identify the top 5 for each category.

Results

Top 5 knowledge gaps included developing therapies for neuroprotection; improving understanding of the pathophysiology, mechanisms, and natural history of PCABI; deploying precision medicine approaches; optimizing resuscitation and CPR quality; and determining optimal timing for and duration of interventions. Top 5 barriers to translation included patient heterogeneity; nihilism & lack of knowledge about cardiac arrest; challenges with the translational pipeline; absence of mechanistic biomarkers; and inaccurate neuro-triage and neuroprognostication. Top 5 research priorities focused on translational research and trial optimization; addressing patient heterogeneity and individualized interventions; improving understanding of pathophysiology and mechanisms; developing mechanistic and outcome biomarkers across post-CA time course; and improving implementation of science and technology.

Conclusion

This overview can serve as a guide to transform the care and outcome of patients with PCABI. Addressing these topics has the potential to improve both research and clinical care in the field of neuroprotection for PCABI.

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.

Cardiopulmonary Resuscitation May Not Stop Glutamate Release in the Cerebral Cortex

BACKGROUND

Cardiopulmonary resuscitation (CPR) may not be sufficient to halt the progression of brain damage. Using extracellular glutamate concentration as a marker for neuronal damage, we quantitatively evaluated the degree of brain damage during resuscitation without return of spontaneous circulation.

MATERIALS AND METHODS

Extracellular cerebral glutamate concentration was measured with a microdialysis probe every 2 minutes for 40 minutes after electrical stimulation-induced cardiac arrest without return of spontaneous circulation in Sprague-Dawley rats. The rats were divided into 3 groups (7 per group) according to the treatment received during the 40 minutes observation period: mechanical ventilation without chest compression (group V); mechanical ventilation and chest compression (group VC) and; ventilation, chest compression and brain hypothermia (group VCH). Chest compression (20 min) and hypothermia (40 min) were initiated 6 minutes after the onset of cardiac arrest.

RESULTS

Glutamate concentration increased in all groups after cardiac arrest. Although after the onset of chest compression, glutamate concentration showed a significant difference at 2 min and reached the maximum at 6 min (VC group; 284±48 μmol/L vs. V group 398±126 μmol/L, P =0.003), there was no difference toward the end of chest compression (513±61 μmol/L vs. 588±103 μmol/L, P =0.051). In the VCH group, the initial increase in glutamate concentration was suddenly suppressed 2 minutes after the onset of brain hypothermia.

CONCLUSIONS

CPR alone reduced the progression of brain damage for a limited period but CPR in combination with brain cooling strongly suppressed increases in glutamate levels.

General Critical Care, Temperature Control, and End-of-Life Decision Making in Patients Resuscitated from Cardiac Arrest

Cardiac arrest affects millions of people per year worldwide. Although advances in cardiopulmonary resuscitation and intensive care have improved outcomes over time, neurologic impairment and multiple organ dysfunction continue to be associated with a high mortality rate. The pathophysiologic mechanisms underlying the post-resuscitation disease are complex, and a coordinated, evidence-based approach to post-resuscitation care has significant potential to improve survival. Critical care management of patients resuscitated from cardiac arrest focuses on the identification and treatment of the underlying cause(s), hemodynamic and respiratory support, organ protection, and active temperature control. This review provides a state-of-the-art appraisal of critical care management of the post-cardiac arrest patient.

Use of a novel smartphone-based application tool for enrolment and randomisation in pre-hospital clinical trials

The effective recruitment and randomisation of patients in pre-hospital clinical trials presents unique challenges. Owing to the time critical nature of many pre-hospital emergencies and limited resourcing, the use of traditional methods of randomisation that may include centralised telephone or web-based systems are often not practicable or feasible. Previous technological limitations have necessitated that pre-hospital trialists strike a compromise between implementing pragmatic, deliverable study designs, and robust enrolment and randomisation methodologies. In this commentary piece, we present a novel smartphone-based solution that has the potential to align pre-hospital clinical trial recruitment processes to that of best-in-practice in-hospital and ambulatory care setting studies. Running title: Smartphone application based randomisation in pre-hospital clinical trials.

Targeted Temperature Management in Cardiac Arrest: An Updated Narrative Review

The established benefits of cooling along with development of sophisticated methods to safely and precisely induce, maintain, monitor, and reverse hypothermia have led to the development of targeted temperature management (TTM). Early trials in human subjects showed that hypothermia conferred better neurological outcomes when compared to normothermia among survivors of cardiac arrest, leading to guidelines recommending targeted hypothermia in this patient population. Multiple studies have sought to explore and compare the benefit of hypothermia in various subgroups of patients, such as survivors of out-of-hospital cardiac arrest versus in-hospital cardiac arrest, and survivors of an initial shockable versus non-shockable rhythm. Larger and more recent trials have shown no statistically significant difference in neurological outcomes between patients with targeted hypothermia and targeted normothermia; further, aggressive cooling is associated with a higher incidence of multiple systemic complications. Based on this data, temporal trends have leaned towards using a lenient temperature target in more recent times. Current guidelines recommend selecting and maintaining a constant target temperature between 32 and 36 °C for those patients in whom TTM is used (strong recommendation, moderate-quality evidence), as soon as possible after return of spontaneous circulation is achieved and airway, breathing (including mechanical ventilation), and circulation are stabilized. The comparative benefit of lower (32-34 °C) versus higher (36 °C) temperatures remains unknown, and further research may help elucidate this. Any survivor of cardiac arrest who is comatose (defined as unarousable unresponsiveness to external stimuli) should be considered as a candidate for TTM regardless of the initial presenting rhythm, and the decision to opt for targeted hypothermia versus targeted normothermia should be made on a case-by-case basis.

2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimizing pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.

Recent developments and controversies in therapeutic hypothermia after cardiopulmonary resuscitation

Therapeutic hypothermia was recommended as the only neuroprotective treatment in comatose patients after return of spontaneous circulation (ROSC). With new evidence suggesting a similar neuroprotective effect of 36 °C and 33 °C, the term "therapeutic hypothermia" was substituted by "targeted temperature management" in 2011, which in turn was replaced by the term "temperature control" in 2022 because of new evidence of the similar effects of target normothermia and 33 °C. However, there is no clear consensus on the efficacy of therapeutic hypothermia. In this article, we provide an overview of the recent evidence from basic and clinical research related to therapeutic hypothermia and re-evaluate its application as a post-ROSC neuroprotective intervention in clinical settings.

Research progress of selective brain cooling methods in the prehospital care for stroke patients: A narrative review

Over the past four decades, therapeutic hypothermia (TH) has long been suggested as a promising neuroprotective treatment of acute ischemic stroke (AIS). Much attention has focus on keeping the hypothermic benefits and removing side effects of systemic hypothermia. In the past few years, the advent of intravenous thrombolysis and endovascular thrombectomy has taken us into a reperfusion era of AIS treatment. With recent research emphasizing ways to plus neuroprotective treatments to reperfusion therapy, the spotlight is now shifting toward the study of how selective brain hypothermia can offset the drawbacks of systemic hypothermia and be applied in prehospital condition. This mini-review summarizes current brain cooling methods that can be used for inducing selective hypothermia in prehospital care. It will guide the future development of selective cooling methods, extend the application of TH in prehospital care, and provide insights into the prospects of selective hypothermia in AIS.

2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimizing pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.

2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimising pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.

Temperature control after cardiac arrest

Most of the patients who die after cardiac arrest do so because of hypoxic-ischemic brain injury (HIBI). Experimental evidence shows that temperature control targeted at hypothermia mitigates HIBI. In 2002, one randomized trial and one quasi-randomized trial showed that temperature control targeted at 32-34 °C improved neurological outcome and mortality in patients who are comatose after cardiac arrest. However, following the publication of these trials, other studies have questioned the neuroprotective effects of hypothermia. In 2021, the largest study conducted so far on temperature control (the TTM-2 trial) including 1900 adults comatose after resuscitation showed no effect of temperature control targeted at 33 °C compared with normothermia or fever control. A systematic review of 32 trials published between 2001 and 2021 concluded that temperature control with a target of 32-34 °C compared with fever prevention did not result in an improvement in survival (RR 1.08; 95% CI 0.89-1.30) or favorable functional outcome (RR 1.21; 95% CI 0.91-1.61) at 90-180 days after resuscitation. There was substantial heterogeneity across the trials, and the certainty of the evidence was low. Based on these results, the International Liaison Committee on Resuscitation currently recommends monitoring core temperature and actively preventing fever (37.7 °C) for at least 72 h in patients who are comatose after resuscitation from cardiac arrest. Future studies are needed to identify potential patient subgroups who may benefit from temperature control aimed at hypothermia. There are no trials comparing normothermia or fever control with no temperature control after cardiac arrest.

Speed of cooling after cardiac arrest in relation to the intervention effect: a sub-study from the TTM2-trial

Background

Targeted temperature management (TTM) is recommended following cardiac arrest; however, time to target temperature varies in clinical practice. We hypothesised the effects of a target temperature of 33 °C when compared to normothermia would differ based on average time to hypothermia and those patients achieving hypothermia fastest would have more favorable outcomes.

Methods

In this post-hoc analysis of the TTM-2 trial, patients after out of hospital cardiac arrest were randomized to targeted hypothermia (33 °C), followed by controlled re-warming, or normothermia with early treatment of fever (body temperature, ≥ 37.8 °C). The average temperature at 4 h (240 min) after return of spontaneous circulation (ROSC) was calculated for participating sites. Primary outcome was death from any cause at 6 months. Secondary outcome was poor functional outcome at 6 months (score of 4–6 on modified Rankin scale).

Results

A total of 1592 participants were evaluated for the primary outcome. We found no evidence of heterogeneity of intervention effect based on the average time to target temperature on mortality (p = 0.17). Of patients allocated to hypothermia at the fastest sites, 71 of 145 (49%) had died compared to 68 of 148 (46%) of the normothermia group (relative risk with hypothermia, 1.07; 95% confidence interval 0.84–1.36). Poor functional outcome was reported in 74/144 (51%) patients in the hypothermia group, and 75/147 (51%) patients in the normothermia group (relative risk with hypothermia 1.01 (95% CI 0.80–1.26).

Conclusions

Using a hospital’s average time to hypothermia did not significantly alter the effect of TTM of 33 °C compared to normothermia and early treatment of fever.

Strategies of Advanced Airway Management in Out-of-Hospital Cardiac Arrest during Intra-Arrest Hypothermia: Insights from the PRINCESS Trial

Background: Trans-nasal evaporative cooling is an effective method to induce intra-arrest therapeutic hypothermia in out-of-hospital cardiac arrest (OHCA). The use of supraglottic airway devices (SGA) instead of endotracheal intubation may enable shorter time intervals to induce cooling. We aimed to study the outcomes in OHCA patients receiving endotracheal intubation (ETI) or a SGA during intra-arrest trans-nasal evaporative cooling. Methods: This is a pre-specified sub-study of the PRINCESS trial (NCT01400373) that included witnessed OHCA patients randomized during resuscitation to trans-nasal intra-arrest cooling vs. standard care followed by temperature control at 33 °C for 24 h. For this study, patients randomized to intra-arrest cooling were stratified according to the use of ETI vs. SGA prior to the induction of cooling. SGA was placed by paramedics in the first-tier ambulance or by physicians or anesthetic nurses in the second tier while ETI was performed only after the arrival of the second tier. Propensity score matching was used to adjust for differences at the baseline between the two groups. The primary outcome was survival with good neurological outcome, defined as cerebral performance category (CPC) 1–2 at 90 days. Secondary outcomes included time to place airway, overall survival at 90 days, survival with complete neurologic recovery (CPC 1) at 90 days and sustained return of spontaneous circulation (ROSC). Results: Of the 343 patients randomized to the intervention arm (median age 64 years, 24% were women), 328 received intra-arrest cooling and had data on the airway method (n = 259 with ETI vs. n = 69 with SGA). Median time from the arrival of the first-tier ambulance to successful airway management was 8 min for ETI performed by second tier and 4 min for SGA performed by the first or second tier (p = 0.001). No significant differences in the probability of good neurological outcome (OR 1.43, 95% CI 0.64–3.01), overall survival (OR 1.26, 95% CI 0.57–2.55), full neurological recovery (OR 1.17, 95% CI 0.52–2.73) or sustained ROSC (OR 0.88, 95% CI 0.50–1.52) were observed between ETI and SGA. Conclusions: Among the OHCA patients treated with trans-nasal evaporative intra-arrest cooling, the use of SGA was associated with a significantly shorter time to airway management and with similar outcomes compared to ETI.

Targeted Temperature Management in Postresuscitation Care After Incorporating Results of the TTM2 Trial

Cardiac arrest still accounts for a substantial proportion of cardiovascular related deaths and is associated with a tremendous risk of neurological injury and, among the few survivors, poor quality of life. Critical determinants of survival and long‐term functional status after cardiac arrest are timely initiation of cardiopulmonary resuscitation and use of an external defibrillator for patients with a shockable rhythm. Outcomes are still far from satisfactory, despite ongoing efforts to improve cardiac arrest response systems, as well as elaborate postresuscitation algorithms. Targeted temperature management at the wide range between 32 °C and 36 °C has been one of the main therapeutic strategies to improve neurological outcome in postresuscitation care. This recommendation has been mainly based on 2 small randomized trials that were published 20 years ago. Most recent data derived from the TTM2 (Targeted Hypothermia Versus Targeted Normothermia After Out‐of‐Hospital Cardiac Arrest) trial, which included 1861 patients, challenge this strategy. It showed no benefit of targeted hypothermia at 33 °C over normothermia at 36 °C to 37.5 °C with fever prevention. Because temperature management at lower temperatures also correlated with an increased risk of side effects without any benefit in the TTM2 trial, a modification of the guidelines with harmonizing temperature management to normothermia might be necessary.

Intra-Arrest Therapeutic Hypothermia and Neurologic Outcome in Patients Admitted after Out-of-Hospital Cardiac Arrest: A Post Hoc Analysis of the Princess Trial

Background: Despite promising results, the role of intra-arrest hypothermia in out-of-hospital cardiac arrest (OHCA) remains controversial. The aim of this study was to assess the effects of trans-nasal evaporative cooling (TNEC) during resuscitation on neurological recovery in OHCA patients admitted alive to the hospital. Methods: A post hoc analysis of the PRINCESS trial, including only patients admitted alive to the hospital, either assigned to TNEC or standard of care during resuscitation. The primary endpoint was favorable neurological outcome (FO) defined as a Cerebral Performance Category (CPC) of 1–2 at 90 days. The secondary outcomes were overall survival at 90 days and CPC 1 at 90 days. Subgroup analyses were performed according to the initial cardiac rhythm. Results: A total of 149 patients in the TNEC and 142 in the control group were included. The number of patients with CPC 1–2 at 90 days was 56/149 (37.6%) in the intervention group and 45/142 (31.7%) in the control group (p = 0.29). Survival and CPC 1 at 90 days was observed in 60/149 patients (40.3%) vs. 52/142 (36.6%; p = 0.09) and 50/149 (33.6%) vs. 35/142 (24.6%; p = 0.11) in the two groups. In the subgroup of patients with an initial shockable rhythm, the number of patients with CPC 1 at 90 days was 45/83 (54.2%) in the intervention group and 27/78 (34.6%) in the control group (p = 0.01). Conclusions: In this post hoc analysis of admitted OHCA patients, no statistically significant benefits of TNEC on neurological outcome at 90 days was found. In patients with initial shockable rhythm, TNEC was associated with increased full neurological recovery.

Selective Cerebrospinal Fluid Hypothermia: Bioengineering Development and In Vivo Study of an Intraventricular Cooling Device (V-COOL)

Hypothermia is a promising therapeutic strategy for severe vasospasm and other types of non-thrombotic cerebral ischemia, but its clinical application is limited by significant systemic side effects. We aimed to develop an intraventricular device for the controlled cooling of the cerebrospinal fluid, to produce a targeted hypothermia in the affected cerebral hemisphere with a minimal effect on systemic temperature. An intraventricular cooling device (acronym: V-COOL) was developed by in silico modelling, in vitro testing, and in vivo proof-of-concept application in healthy Wistar rats (n = 42). Cerebral cortical temperature, rectal temperature, and intracranial pressure were monitored at increasing flow rate (0.2 to 0.8 mL/min) and duration of application (10 to 60 min). Survival, neurological outcome, and MRI volumetric analysis of the ventricular system were assessed during the first 24 h. The V-COOL prototyping was designed to minimize extra-cranial heat transfer and intra-cranial pressure load. In vivo application of the V-COOL device produced a flow rate-dependent decrease in cerebral cortical temperature, without affecting systemic temperature. The target degree of cerebral cooling (- 3.0 °C) was obtained in 4.48 min at the flow rate of 0.4 mL/min, without significant changes in intracranial pressure. Survival and neurological outcome at 24 h showed no significant difference compared to sham-treated rats. MRI study showed a transient dilation of the ventricular system (+ 38%) in a subset of animals. The V-COOL technology provides an effective, rapid, selective, and safe cerebral cooling to a clinically relevant degree of - 3.0 °C.

Soft, bioresorbable coolers for reversible conduction block of peripheral nerves

Implantable devices capable of targeted and reversible blocking of peripheral nerve activity may provide alternatives to opioids for treating pain. Local cooling represents an attractive means for on-demand elimination of pain signals, but traditional technologies are limited by rigid, bulky form factors; imprecise cooling; and requirements for extraction surgeries. Here, we introduce soft, bioresorbable, microfluidic devices that enable delivery of focused, minimally invasive cooling power at arbitrary depths in living tissues with real-time temperature feedback control. Construction with water-soluble, biocompatible materials leads to dissolution and bioresorption as a mechanism to eliminate unnecessary device load and risk to the patient without additional surgeries. Multiweek in vivo trials demonstrate the ability to rapidly and precisely cool peripheral nerves to provide local, on-demand analgesia in rat models for neuropathic pain.

Selective Brain Cooling: A New Horizon of Neuroprotection

Therapeutic hypothermia (TH), which prevents irreversible neuronal necrosis and ischemic brain damage, has been proven effective for preventing ischemia-reperfusion injury in post-cardiac arrest syndrome and neonatal encephalopathy in both animal studies and clinical trials. However, lowering the whole-body temperature below 34°C can lead to severe systemic complications such as cardiac, hematologic, immunologic, and metabolic side effects. Although the brain accounts for only 2% of the total body weight, it consumes 20% of the body's total energy at rest and requires a continuous supply of glucose and oxygen to maintain function and structural integrity. As such, theoretically, temperature-controlled selective brain cooling (SBC) may be more beneficial for brain ischemia than systemic pan-ischemia. Various SBC methods have been introduced to selectively cool the brain while minimizing systemic TH-related complications. However, technical setbacks of conventional SBCs, such as insufficient cooling power and relatively expensive coolant and/or irritating effects on skin or mucosal interfaces, limit its application to various clinical settings. This review aimed to integrate current literature on SBC modalities with promising therapeutic potential. Further, future directions were discussed by exploring studies on interesting coping skills in response to environmental or stress-induced hyperthermia among wild animals, including mammals and birds.

Targeted Temperature Management for Cardiac Arrest Due to Non-shockable Rhythm: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Targeted temperature management (TTM) is recommended in adult patients following cardiac arrest (CA) with any rhythm. However, as to non-shockable (NSR) CA, high-quality evidence of TTM supporting its practices remains uncertain. Thus, we aimed to conduct a systematic review and meta-analysis with randomized controlled trials (RCTs) to explore the efficacy and safety of TTM in this population.

Methods

We searched PubMed, Embase, and Cochrane library databases for potential trials from inception through Aug 25, 2021. RCTs evaluating TTM for CA adults due to NSR were included, regardless of the timing of cooling initiation. Outcome measurements were mortality and good neurological function. We used the Cochrane bias tools to evaluate the quality of the included studies. Heterogeneity, subgroup analyses, and sensitivity analysis were investigated to test the robustness of the primary outcomes.

Results

A total of 14 RCTs with 4,009 adults were eligible for the final analysis. All trials had a low to moderate risk of bias. Of the included trials, six compared NSR patients with or without TTM, while eight compared pre-hospital to in-hospital TTM. Pooled data showed that TTM was not associated with improved mortality (Risk ratio [RR] 1.00; 95% CI, 0.944–1.05; P = 0.89, I² = 0%) and good neurological outcome (RR 1.18; 95% CI 0.90–1.55; P = 0.22, I² = 8%). Similarly, use of pre-hospital TTM resulted in neither an improved mortality (RR 0.99, 95% CI 0.97–1.03; I² = 0%, P = 0.32) nor favorable neurological outcome (RR 1.13, 95% CI 0.93–1.38; I² = 0%, P = 0.22). These results were further confirmed in the sensitivity analyses and subgroup analyses.

Conclusions

Our results showed that using the TTM strategy did not significantly affect the mortality and neurologic outcomes in CA survival presenting initial NSR.

Temperature control after cardiac arrest: friend or foe

PURPOSE OF REVIEW

Most patients who are successfully resuscitated after cardiac arrest are initially comatose and require mechanical ventilation and other organ support in an ICU. Best practice has been to cool these patients and control their temperature at a constant value in the range of 32-36 oC for at least 24 h. But the certainty of the evidence for this practice is increasingly being challenged. This review will summarize the evidence on key aspects of temperature control in comatose postcardiac arrest patients.

RECENT FINDINGS

The Targeted Temperature Management 2 (TTM-2) trial documented no difference in 6-month mortality among comatose postcardiac arrest patients managed at 33 oC vs. targeted normothermia. A systematic review and meta-analysis completed by the Advanced Life Support (ALS) Task Force of the International Liaison Committee on Resuscitation (ILCOR) concluded that temperature control with a target of 32-34 °C did not improve survival or favourable functional outcome after cardiac arrest. Two observational studies have documented an association between predicted moderate hypoxic-ischaemic brain injury and better outcome with temperature control at 33-34 oC compared with 35-36 oC.

SUMMARY

We suggest actively preventing fever by targeting a temperature 37.5 oC or less for those patients who remain comatose following return of spontaneous circulation (ROSC) after cardiac arrest.

Targeted Temperature Management: A Program Evaluation

In the United States, more than 350 000 cardiac arrests occur annually. The survival rate after an out-of-hospital cardiac arrest remains low. The majority of patients who have return of spontaneous circulation will die of complications of hypoxic-ischemic brain injury. Targeted temperature management is the only recommended neuroprotective measure for those who do not regain consciousness after return of spontaneous circulation. Despite current practices, a review of the literature revealed that evidence on the ideal time to achieve target temperature after return of spontaneous circulation remains equivocal. A program evaluation of a targeted temperature management program at an academic center was performed; the focus was on timing components of targeted temperature management. The program evaluation revealed that nurse-driven, evidence-based protocols can lead to optimal patient outcomes in this low-frequency, high-impact therapy.

ERC-ESICM guidelines on temperature control after cardiac arrest in adults

The aim of these guidelines is to provide evidence‑based guidance for temperature control in adults who are comatose after resuscitation from either in-hospital or out-of-hospital cardiac arrest, regardless of the underlying cardiac rhythm. These guidelines replace the recommendations on temperature management after cardiac arrest included in the 2021 post-resuscitation care guidelines co-issued by the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM). The guideline panel included thirteen international clinical experts who authored the 2021 ERC-ESICM guidelines and two methodologists who participated in the evidence review completed on behalf of the International Liaison Committee on Resuscitation (ILCOR) of whom ERC is a member society. We followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and grade recommendations. The panel provided suggestions on guideline implementation and identified priorities for future research. The certainty of evidence ranged from moderate to low. In patients who remain comatose after cardiac arrest, we recommend continuous monitoring of core temperature and actively preventing fever (defined as a temperature > 37.7 °C) for at least 72 hours. There was insufficient evidence to recommend for or against temperature control at 32-36 °C or early cooling after cardiac arrest. We recommend not actively rewarming comatose patients with mild hypothermia after return of spontaneous circulation (ROSC) to achieve normothermia. We recommend not using prehospital cooling with rapid infusion of large volumes of cold intravenous fluids immediately after ROSC.

ERC-ESICM guidelines on temperature control after cardiac arrest in adults

The aim of these guidelines is to provide evidence‑based guidance for temperature control in adults who are comatose after resuscitation from either in-hospital or out-of-hospital cardiac arrest, regardless of the underlying cardiac rhythm. These guidelines replace the recommendations on temperature management after cardiac arrest included in the 2021 post-resuscitation care guidelines co-issued by the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM). The guideline panel included thirteen international clinical experts who authored the 2021 ERC-ESICM guidelines and two methodologists who participated in the evidence review completed on behalf of the International Liaison Committee on Resuscitation (ILCOR) of whom ERC is a member society. We followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and grade recommendations. The panel provided suggestions on guideline implementation and identified priorities for future research. The certainty of evidence ranged from moderate to low. In patients who remain comatose after cardiac arrest, we recommend continuous monitoring of core temperature and actively preventing fever (defined as a temperature > 37.7 °C) for at least 72 h. There was insufficient evidence to recommend for or against temperature control at 32-36 °C or early cooling after cardiac arrest. We recommend not actively rewarming comatose patients with mild hypothermia after return of spontaneous circulation (ROSC) to achieve normothermia. We recommend not using prehospital cooling with rapid infusion of large volumes of cold intravenous fluids immediately after ROSC.

[Targeted temperature management after cardiac arrest : What is new?]

The current guidelines of the European Resuscitation Council recommend targeted temperature management to improve functional neurological outcome in comatose survivors after cardiac arrest. With the pathophysiological background of hypothermia-induced neuroprotection for prevention of hypoxic-ischemic encephalopathy, targeted temperature management is a key measure and represents a central aspect in postresuscitation care.In the 2021 guidelines the application of targeted temperature management in postresuscitation care has been recommended for all rhythms and irrespective of the location of cardiac arrest. Targeted temperature management is advocated for adult patients who remain unresponsive following return of spontaneous circulation (ROSC) after either out-of-hospital cardiac arrest or in-hospital cardiac arrest. The body temperature should be maintained at a constant value between 32 °C and 36 °C for at least 24 h. To avoid rebound hyperthermia, fever following targeted temperature management, defined as a temperature above 37.7 °C, should be prevented and treated for at least 72 h after ROSC in persistently comatose patients. The routine use of prehospital cooling by rapid infusion of large volumes of cold i.v. fluid immediately after ROSC is not recommended.Based on a systematic review of the current literature, this article summarizes the results of randomized trials and new findings on targeted temperature management in comatose adult patients after cardiac arrest. The review has a particular focus on the most recent evidence regarding the optimum range of target temperatures. Furthermore, recent data on preclinical management, different patient populations, the duration of targeted temperature management, cooling methods and rebound hyperthermia are discussed.The impact of targeted temperature management on neurological outcome after cardiac arrest has been a matter of controversy. Despite contradictory results and heterogeneity of study designs, the current evidence supports the relevance and the necessity of strict temperature control in postresuscitation care for neuroprotection and improvement in functional neurological outcomes.

Targeted temperature management in adult cardiac arrest: Systematic review and meta-analysis

AIM

To perform a systematic review and meta-analysis on targeted temperature management in adult cardiac arrest patients.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched on June 17, 2021 for clinical trials. The population included adult patients with cardiac arrest. The review included all aspects of targeted temperature management including timing, temperature, duration, method of induction and maintenance, and rewarming. Two investigators reviewed trials for relevance, extracted data, and assessed risk of bias. Data were pooled using random-effects models. Certainty of evidence was evaluated using GRADE.

RESULTS

The systematic search identified 32 trials. Risk of bias was assessed as intermediate for most of the outcomes. For targeted temperature management with a target of 32-34 °C vs. normothermia (which often required active cooling), 9 trials were identified, with six trials included in meta-analyses. Targeted temperature management with a target of 32-34 °C did not result in an improvement in survival (risk ratio: 1.08 [95%CI: 0.89, 1.30]) or favorable neurologic outcome (risk ratio: 1.21 [95%CI: 0.91, 1.61]) at 90 to 180 days after the cardiac arrest (low certainty of evidence). Three trials assessed different hypothermic temperature targets and found no difference in outcomes (low certainty of evidence). Ten trials were identified comparing prehospital cooling vs. no prehospital cooling with no improvement in survival (risk ratio: 1.01 [95%CI: 0.92, 1.11]) or favorable neurologic outcome (risk ratio: 1.00 [95%CI: 0.90, 1.11]) at hospital discharge (moderate certainty of evidence).

CONCLUSIONS

Among adult patients with cardiac arrest, the use of targeted temperature management at 32-34 °C, when compared to normothermia, did not result in improved outcomes in this meta-analysis. There was no effect of initiating targeted temperature management prior to hospital arrival. These findings warrant an update of international cardiac arrest guidelines.

Insight into the use of tympanic temperature during target temperature management in emergency and critical care: a scoping review

BACKGROUND

Target temperature management (TTM) is suggested to reduce brain damage in the presence of global or local ischemia. Prompt TTM application may help to improve outcomes, but it is often hindered by technical problems, mainly related to the portability of cooling devices and temperature monitoring systems. Tympanic temperature (T_Ty) measurement may represent a practical, non-invasive approach for core temperature monitoring in emergency settings, but its accuracy under different TTM protocols is poorly characterized. The present scoping review aimed to collect the available evidence about T_Ty monitoring in TTM to describe the technique diffusion in various TTM contexts and its accuracy in comparison with other body sites under different cooling protocols and clinical conditions.

METHODS

The scoping review was conducted following the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis extension for scoping reviews (PRISMA-ScR). PubMed, Scopus, and Web of Science electronic databases were systematically searched to identify studies conducted in the last 20 years, where T_Ty was measured in TTM context with specific focus on pre-hospital or in-hospital emergency settings.

RESULTS

The systematic search identified 35 studies, 12 performing T_Ty measurements during TTM in healthy subjects, 17 in patients with acute cardiovascular events, and 6 in patients with acute neurological diseases. The studies showed that T_Ty was able to track temperature changes induced by either local or whole-body cooling approaches in both pre-hospital and in-hospital settings. Direct comparisons to other core temperature measurements from other body sites were available in 22 studies, which showed a faster and larger change of T_Ty upon TTM compared to other core temperature measurements. Direct brain temperature measurements were available only in 3 studies and showed a good correlation between T_Ty and brain temperature, although T_Ty displayed a tendency to overestimate cooling effects compared to brain temperature.

CONCLUSIONS

T_Ty was capable to track temperature changes under a variety of TTM protocols and clinical conditions in both pre-hospital and in-hospital settings. Due to the heterogeneity and paucity of comparative temperature data, future studies are needed to fully elucidate the advantages of T_Ty in emergency settings and its capability to track brain temperature.

Effect of intra-arrest trans-nasal evaporative cooling in out-of-hospital cardiac arrest: a pooled individual participant data analysis

Background

Randomized trials have shown that trans-nasal evaporative cooling initiated during CPR (i.e. intra-arrest) effectively lower core body temperature in out-of-hospital cardiac arrest patients. However, these trials may have been underpowered to detect significant differences in neurologic outcome, especially in patients with initial shockable rhythm.

Methods

We conducted a post hoc pooled analysis of individual data from two randomized trials including 851 patients who eventually received the allocated intervention and with available outcome (“as-treated” analysis). Primary outcome was survival with favourable neurological outcome at hospital discharge (Cerebral Performance Category [CPC] of 1–2) according to the initial rhythm (shockable vs. non-shockable). Secondary outcomes included complete neurological recovery (CPC 1) at hospital discharge.

Results

Among the 325 patients with initial shockable rhythms, favourable neurological outcome was observed in 54/158 (34.2%) patients in the intervention and 40/167 (24.0%) in the control group (RR 1.43 [confidence intervals, CIs 1.01–2.02]). Complete neurological recovery was observed in 40/158 (25.3%) in the intervention and 27/167 (16.2%) in the control group (RR 1.57 [CIs 1.01–2.42]). Among the 526 patients with initial non-shockable rhythms, favourable neurological outcome was in 10/259 (3.8%) in the intervention and 13/267 (4.9%) in the control group (RR 0.88 [CIs 0.52–1.29]; p = 0.67); survival and complete neurological recovery were also similar between groups. No significant benefit was observed for the intervention in the entire population.

Conclusions

In this pooled analysis of individual data, intra-arrest cooling was associated with a significant increase in favourable neurological outcome in out-of-hospital cardiac arrest patients with initial shockable rhythms. Future studies are needed to confirm the potential benefits of this intervention in this subgroup of patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03583-9.

Inadvertent hypothermia after endovascular therapy is not associated with improved outcome in stroke due to anterior circulation large vessel occlusion

BACKGROUND AND PURPOSE

Hypothermia may be neuroprotective in acute ischemic stroke. Patients with anterior circulation large vessel occlusion (acLVO) are frequently hypothermic after endovascular therapy (EVT). We sought to determine whether this inadvertent hypothermia is associated with improved outcome.

METHODS

We extracted data of consecutive patients (January 2016 to May 2019) who received EVT for acLVO from our prospective EVT register of all patients screened for EVT at our tertiary stroke center. We assessed functional outcome at 3 months and performed multivariate analysis to calculate adjusted risk ratios (aRRs) for favorable outcome (modified Rankin Scale scores = 0-2) and mortality across patients who were hypothermic (<36°C) and patients who were normothermic (≥36°C to <37.6°C) after EVT. Moreover, we compared the frequency of complications between these groups.

RESULTS

Among 837 patients screened, 416 patients received EVT for acLVO and fulfilled inclusion criteria (200 [48.1%] male, mean age = 76 ± 16 years, median National Institutes of Health Stroke Scale score = 16, interquartile range [IQR] = 12-20). Of these, 209 patients (50.2%) were hypothermic (median temperature = 35.2°C, IQR = 34.7-35.7) and 207 patients were normothermic (median temperature = 36.4°C, IQR = 36.1-36.7) after EVT. In multivariate analysis, hypothermia was not associated with favorable outcome (aRR = 0.99, 95% confidence interval [CI] = 0.75-1.31) and mortality (aRR = 1.18, 95% CI = 0.84-1.66). More hypothermic patients suffered from pneumonia (36.4% vs. 25.6%, p = 0.02) and bradyarrhythmia (52.6% vs. 16.4%, p < 0.001), whereas thromboembolic events were distributed evenly (5.7% vs. 6.8%, not significant).

CONCLUSIONS

Inadvertent hypothermia after EVT for acLVO is not associated with improved functional outcome or reduced mortality but is associated with an increased rate of pneumonia and bradyarrhythmia in patients with acute ischemic stroke.

Thermoregulation in post-cardiac arrest patients treated with targeted temperature management

OBJECTIVE

Evaluate the relationship between heat generation during rewarming in post-cardiac arrest patients receiving targeted temperature management (TTM) as a surrogate of thermoregulatory ability and clinical outcomes.

METHODS

This is a prospective observational single-centre study conducted at an urban tertiary-care hospital. We included post-cardiac arrest adults who received TTM via surface cooling device between April 2018 and June 2019.

RESULTS

Patient heat generation was calculated by multiplying the inverse of the average machine water temperature with time to rewarm to 37 °C and standardized in two ways to account for target temperature variation: (1) divided by number of degrees between target temperature and 37 °C, and (2) limited to when patient was rewarmed from 36 °C to 37 °C. The primary outcome was poor neurologic status, defined as Cerebral Performance Category (CPC) score 3-5, and the secondary outcome was 30-day survival. Sixty-six patients were included: 45 (68%) had a CPC-score of 3-5 and 23 (35%) were alive at 30 days. Besides initial rhythm and arrest downtime, baseline characteristics were similar between outcomes. Heat generation was not associated with poor neurological outcome (CPC 3-5: 6.6 [IQR: 6.1, 7.4] versus CPC 1-2: 6.6 [IQR: 5.7, 7.6], p = 0.89) or survival at 30 days (non-survivors: 6.6 [IQR: 6.6, 7.4] vs. survivors: 6.6 [IQR: 5.7, 8.0, p = 0.78]).

CONCLUSION

Heat generation during rewarming was not associated with neurologic outcomes. However, there was a relationship between poor neurological outcome and higher median water temperatures. Time to rewarm was prolonged in patients with poor neurological outcome.

European Resuscitation Council and European Society of Intensive Care Medicine guidelines 2021: post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation and organ donation.

European Resuscitation Council and European Society of Intensive Care Medicine Guidelines 2021: Post-resuscitation care

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have collaborated to produce these post-resuscitation care guidelines for adults, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include the post-cardiac arrest syndrome, diagnosis of cause of cardiac arrest, control of oxygenation and ventilation, coronary reperfusion, haemodynamic monitoring and management, control of seizures, temperature control, general intensive care management, prognostication, long-term outcome, rehabilitation, and organ donation.

Impact of therapeutic hypothermia during cardiopulmonary resuscitation on neurologic outcome: A systematic review and meta-analysis

BACKGROUND

Therapeutic cooling initiated during cardiopulmonary resuscitation (intra arrest therapeutic hypothermia, IATH) provided diverging effect on neurological outcome of out-of-hospital cardiac arrest (OHCA) patients depending on the initial cardiac rhythm and the cooling methods used.

METHODS

We performed a systematic search of PubMed, EMBASE and the CENTRAL databases using established Medical Subject Headings (MeSH) terms for IATH and OHCA. Only studies comparing IATH to standard in-hospital targeted temperature management (TTM) were selected. We used the revised Cochrane RoB-2 and the Newcastle-Ottawa scale tool to assess risk of bias of each study. Primary outcome was favorable neurological outcome (FO); secondary outcomes included return of spontaneous circulation (ROSC) rate and survival to hospital discharge.

RESULTS

Out of 20,950 studies, 8 studies (n = 3493 patients, including 4 randomized trials, RCTs) were included in the final analysis. Compared to controls, the use of IATH was not associated with improved FO (OR 0.96 [95% CIs 0.68-1.37]; p = 0.84), increased ROSC rate (OR 1.11 [95% CIs 0.83-1.49]; p = 0.46) or survival (OR 0.91 [95% CIs 0.73-1.14]; p = 0.43). Significant heterogeneity among studies was observed for the analysis of ROSC rate (I² = 69%). Trans-nasal evaporative cooling and cold fluids were explored in two RCTs each and no differences were observed on FO, event when only patients with an initial shockable rhythm were analyzed (OR 1.62 [95% CI 1.00-2.64]; p = 0.05].

CONCLUSIONS

In this meta-analysis, IATH was not associated with improved neurological outcome when compared to standard in-hospital TTM, based on very low certainty of evidence.

CLINICAL TRIAL REGISTRATION

PROSPERO (CRD42019130322).

The impact of intra-arrest hypothermia

PURPOSE OF REVIEW

To address the impact of therapeutic hypothermia induced already during cardiopulmonary resuscitation (i.e. intra-arrest cooling) and its association with neurologic functional outcome.

RECENT FINDINGS

Intra-arrest cooling is superior than post-ROSC cooling to mitigate brain injuries in experimental models of cardiac arrest. The delayed initiation of hypothermia in human studies may not have adequately addressed the underlying pathophysiology of ischemia and reperfusion. The assessment of early initiation of cooling has been complicated by increased rate of hemodynamic adverse events caused by infusion of cold intravenous fluids. These adverse events have been more deleterious in patients with initial shockable rhythms. A recent randomized study shows that an alternative intra-arrest cooling method using trans-nasal evaporative cooling was well tolerated and effective to shorten time to target temperature. However, the neurologic outcomes (CPC 1-2 at 90 days) in favor of intra-arrest cooling compared to hospital cooling (34.8% vs 25.9%, P = 0.11) in patients with initial shockable rhythms did not reach statistical significance.

SUMMARY

Therapeutic intra-arrest hypothermia can be initiated safely at the scene of the arrest using transnasal evaporative cooling. The potential beneficial effect of intra-arrest cooling on neurologic recovery in patients with initial shockable rhythms should be explored further.

Door-to-Targeted Temperature Management Initiation Time and Outcomes in Out-of-Hospital Cardiac Arrest: Insights From the Continuous Chest Compressions Trial

Background

Targeted temperature management (TTM) is a recommended treatment modality to improve neurological outcomes in patients with out‐of‐hospital cardiac arrest. The impact of the duration from hospital admission to TTM initiation (door‐to‐TTM; DTT) on clinical outcomes has not been well elucidated. We hypothesized that shorter DTT initiation intervals would be associated with improved survival with favorable neurological outcome.

Methods and Results

We performed a post hoc analysis of nontraumatic paramedic‐treated out‐of‐hospital cardiac arrests. The primary outcome was favorable neurological status at hospital discharge, with a secondary outcome of survival to discharge. We fit a logistic regression analysis to determine the association of early compared with delayed DTT, dichotomized by the median DTT duration, and outcomes. Of 3805 patients enrolled in the CCC (Continuous Chest Compressions) Trial in British Columbia, 570 were included in this analysis. There was substantial variation in DTT among patients receiving TTM. The median DTT duration was 122 minutes (interquartile range 35‐218). Favorable neurological outcomes in the early and delayed DTT groups were 48% and 38%, respectively. Compared with delayed DTT (interquartile range 167‐319 minutes), early DTT (interquartile range 20‐81 minutes) was associated with survival (adjusted odds ratio 1.56, 95% CI 1.02‐2.38) but not with favorable neurological outcomes (adjusted odds ratio 1.45, 95% CI, 0.94‐2.22) at hospital discharge.

Conclusions

There was wide variability in the initiation of TTM among comatose out‐of‐hospital cardiac arrest survivors. Initiation of TTM within 122 minutes of hospital admission was associated with improved survival. These results support in‐hospital efforts to achieve early DTT among out‐of‐hospital cardiac arrest patients admitted to the hospital.

See Editorial Schenone and Menon

Updates in Cardiac Arrest Resuscitation

There are approximately 350,000 out-of-hospital cardiac arrests and 200,000 in-hospital cardiac arrests annually in the United States, with survival rates of approximately 5% to 10% and 24%, respectively. The critical factors that have an impact on cardiac arrest survival include prompt recognition and activation of prehospital care, early cardiopulmonary resuscitation, and rapid defibrillation. Advanced life support protocols are continually refined to optimize intracardiac arrest management and improve survival with favorable neurologic outcome. This article focuses on current treatment recommendations for adult nontraumatic cardiac arrest, with emphasis on the latest evidence and controversies regarding intracardiac arrest management.

Safety and Feasibility of a Novel Transnasal Cooling Device to Induce Normothermia in Febrile Cerebrovascular Patients

BACKGROUND

Inducing normothermia with surface cooling temperature modulating devices (TMDs) is cumbersome and often associated with significant shivering. We tested the safety and feasibility of a novel transnasal evaporative cooling device to induce and maintain normothermia in febrile patients following ischemic and hemorrhagic stroke.

METHODS

A single-center study utilizing the CoolStat® transnasal cooling device was used to achieve core temperature reduction in mechanically ventilated stroke patients with fever (T ≥ 38.3 C) refractory to acetaminophen by inducing an evaporative cooling energy exchange in the nasal turbinates thru a high flow of dehumidified air into the nasal cavity and out through the mouth. Continuous temperature measurements were obtained from tympanic and core (esophageal or bladder) temperature monitors. Safety assessments included continuous monitoring for hypertension, tachycardia, and raised intracranial pressure (when monitored). Otolaryngology (ENT) evaluations were monitored for any device-related nasal mucosal injury with a pre- and post-visual examination. Shivering was assessed every 30 min using the Bedside Shivering Assessment Scale (BSAS). Duration of device use was limited to 8 h, at which time patients were transitioned to routine care for temperature management.

RESULTS

Ten subjects (median age: 54 years, BMI: 32.5 kg/m², 60% men) were enrolled with normothermia achieved in 90% of subjects. One subject did not achieve normothermia and was later refractory to other TMDs. Median baseline temperature was 38.5 ± 0.1 C, with a reduction noted by 4 h (38.5 ± 0.1 vs 37.3 ± 0.8, P < 0.001) and sustained at 8 h (38.5 ± 0.1 vs 37.1 ± 0.7, P = 0.001). Time to normothermia was 2.6 ± 1.9 h. The median BSAS was 0 (range 0-1) with only 4 episodes necessitating meperidine across 76 h of study monitoring. No treatment was discontinued due to safety concerns. ENT evaluations noted no device-related adverse findings.

CONCLUSIONS

Inducing normothermia with a novel transnasal TMD appears to be safe, feasible and not associated with significant shivering. A multicenter trial testing the ability of the CoolStat to maintain normothermia for 24 h is currently underway.

Feasibility and Safety of Transnasal High Flow Air to Reduce Core Body Temperature in Febrile Neurocritical Care Patients: A Pilot Study

BACKGROUND

Fever is an important determinant of prognosis following acute brain injury. Current non-pharmacologic techniques to reduce fever are limited and induce a shivering response. We investigated the safety and efficacy of a novel transnasal unidirectional high flow air device in reducing core body temperature in the neurocritical care unit (NCCU) setting.

METHODS

This pilot study included seven consecutive patients in the NCCU who were febrile (> 37.5 °C) for > 24 h despite standard non-pharmacologic and first-line antipyretic agents. Medical grade high flow air was delivered transnasally using a standard continuous positive airway pressure machine with a positive pressure of 20 cmH₂O for 2 h. Core esophageal and tympanic temperature were continuously monitored.

RESULTS

Mean age was 40 ± 14 yo, and 72% (5/7 patients) were men. Five patients had intracerebral or intraventricular hemorrhage, one subject had transverse myelitis, and the remaining patient had anoxic brain injury due to a cardiac arrest. After 2 h of cooling, core temperature was significantly lower than the baseline pre-cooling temperature (37.3 ± 0.5 °C vs. 38.4 ± 0.6 °C; p < 0.002). Mean transnasal airflow rate was 57.5 ± 6.5 liters per minute. Five of the seven subjects were normothermic at the end of the 2-h period. One subject with severe hyperthermia (39.7 °C) and the other with multiple interruptions to therapy due to technical reasons did not cool. The core temperature within 30 min of cessation of airflow increased and was similar to the pre-cooling baseline temperature (38.3 ± 0.4 °C vs. 38.4 ± 0.6 °C, p = NS). Rate of core cooling was 0.6 ± 0.15 °C per hour at this flow rate. No shivering response was observed. No protocol-related adverse events occurred.

CONCLUSIONS

High flow transnasal air in a unidirectional fashion lowers core body temperature in febrile patients in the NCCU setting. No adverse events were seen, and the process showed no signs of shivering or any other serious side effects during short-term exposure. This pilot study should inform further investigation.