Targeted temperature management guided by the severity of hyperlactatemia for out-of-hospital cardiac arrest patients: a post hoc analysis of a nationwide, multicenter prospective registry

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.

Non-linear association between the time required to reaching temperature targets and the neurological outcome in patients undergoing targeted temperature management after out-of-hospital cardiac arrest: Observational multicentre cohort study

Purpose

We evaluated associations between outcomes and time to achieving temperature targets during targeted temperature management of out-of-hospital cardiac arrest.

Methods

Using Comprehensive Registry of Intensive Care for out-of-hospital cardiac arrest Survival (CRITICAL) study, we enrolled all patients transported to participating hospitals from 1 July 2012 through 31 December 2017 aged ≥ 18 years with out-of-hospital cardiac arrest of cardiac aetiology and who received targeted temperature management in Osaka, Japan. Primary outcome was Cerebral Performance Category scale of 1 or 2 one month after cardiac arrest, designated as "one-month favourable neurological outcome". Non-linear multivariable logistic regression analyses assessed the primary outcome based on time to reaching temperature targets. In patients subdivided into quintiles based on time to achieving temperature targets, multivariable logistic regression calculated adjusted odds ratios and 95% confidence intervals.

Results

We analysed 473 patients. In non-linear multivariable logistic regression analysis, p value for non-linearity was < 0.01. In the first quintile (< 26.7 minutes), second quintile (26.8-89.9 minutes), third quintile (90.0-175.1 minutes), fourth quintile (175.2-352.1 minutes), and fifth quintile (≥ 352.2 minutes), one-month favourable neurological outcome was 32.6% (31/95), 40.0% (36/90), 53.5% (53/99), 57.4% (54/94), and 37.9% (36/95), respectively. Adjusted odds ratios with 95% confidence intervals for one-month favourable neurological outcome in the first, second, third, and fifth quintiles compared with the fourth quintile were 0.38 (0.20 to 0.72), 0.43 (0.23 to 0.81), 0.77 (0.41 to 1.44), and 0.46 (0.25 to 0.87), respectively.

Conclusion

Non-linear multivariable logistic regression analysis could clearly describe the association between neurological outcome in patients with out-of-hospital cardiac arrest and the time from the introduction of targeted temperature management to reaching the temperature targets.

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.

Postresuscitation management

PURPOSE OF REVIEW

To describe the most recent scientific evidence on ventilation/oxygenation, circulation, temperature control, general intensive care, and prognostication after successful resuscitation from adult cardiac arrest.

RECENT FINDINGS

Targeting a lower oxygen target (90-94%) is associated with adverse outcome. Targeting mild hypercapnia is not associated with improved functional outcomes or survival. There is no compelling evidence supporting improved outcomes associated with a higher mean arterial pressure target compared to a target of >65 mmHg. Noradrenalin seems to be the preferred vasopressor. A low cardiac index is common over the first 24 h but aggressive fluid loading and the use of inotropes are not associated with improved outcome. Several meta-analyses of randomized clinical trials show conflicting results whether hypothermia in the 32-34°C range as compared to normothermia or no temperature control improves functional outcome. The role of sedation is currently under evaluation. Observational studies suggest that the use of neuromuscular blockade may be associated with improved survival and functional outcome. Prophylactic antibiotic does not impact on outcome. No single predictor is entirely accurate to determine neurological prognosis. The presence of at least two predictors of severe neurological injury indicates that an unfavorable neurological outcome is very likely.

SUMMARY

Postresuscitation care aims for normoxemia, normocapnia, and normotension. The optimal target core temperature remains a matter of debate, whether to implement temperature management within the 32-34°C range or focus on fever prevention, as recommended in the latest European Resuscitation Council/European Society of Intensive Care Medicine guidelines Prognostication of neurological outcome demands a multimodal approach.

Temperature control after cardiac arrest

Managing temperature is an important part of post-cardiac arrest care. Fever or hyperthermia during the first few days after cardiac arrest is associated with worse outcomes in many studies. Clinical data have not determined any target temperature or duration of temperature management that clearly improves patient outcomes. Current guidelines and recent reviews recommend controlling temperature to prevent hyperthermia. Higher temperatures can lead to secondary brain injury by increasing seizures, brain edema and metabolic demand. Some data suggest that targeting temperature below normal could benefit select patients where this pathology is common. Clinical temperature management should address the physiology of heat balance. Core temperature reflects the heat content of the head and torso, and changes in core temperature result from changes in the balance of heat production and heat loss. Clinical management of patients after cardiac arrest should include measurement of core temperature at accurate sites and monitoring signs of heat production including shivering. Multiple methods can increase or decrease heat loss, including external and internal devices. Heat loss can trigger compensatory reflexes that increase stress and metabolic demand. Therefore, any active temperature management should include specific pharmacotherapy or other interventions to control thermogenesis, especially shivering. More research is required to determine whether individualized temperature management can improve outcomes.

Hypothermia may reduce mortality and improve neurologic outcomes in adult patients treated with VA-ECMO: A systematic review and meta-analysis

BACKGROUND

VA-ECMO can greatly reduce mortality in critically ill patients, and hypothermia attenuates the deleterious effects of ischemia-reperfusion injury. We aimed to study the effects of hypothermia on mortality and neurological outcomes in VA-ECMO patients.

METHODS

A systematic search of the PubMed, Embase, Web of Science, and Cochrane Library databases was performed from the earliest available date to 31 December 2022. The primary outcome was discharge or 28-day mortality and favorable neurological outcomes in VA-ECMO patients, and the secondary outcome was bleeding risk in VA-ECMO patients. The results are presented as odds ratios (ORs) and 95% confidence intervals (CIs). Based on the heterogeneity assessed by the I² statistic, meta-analyses were performed using random or fixed-effects models. GRADE methodology was used to rate the certainty in the findings.

RESULTS

A total of 27 articles (3782 patients) were included. Hypothermia (33-35 °C) lasting at least 24 h can significantly reduce discharge or 28-day mortality (OR, 0.45; 95% CI, 0.33-0.63; I² = 41%) and significantly improve favorable neurological outcomes (OR, 2.08; 95% CI, 1.66-2.61; I² = 3%) in VA-ECMO patients. Additionally, there was no risk associated with bleeding (OR, 1.15; 95% CI, 0.86-1.53; I² = 12%). In our subgroup analysis according to in-hospital or out-of-hospital cardiac arrest, hypothermia reduced short-term mortality in both VA-ECMO-assisted in-hospital (OR, 0.30; 95% CI, 0.11-0.86; I² = 0.0%) and out-of-hospital cardiac arrest (OR, 0.41; 95% CI, 0.25-0.69; I² = 52.3%). Out-of-hospital cardiac arrest patients assisted by VA-ECMO for favorable neurological outcomes were consistent with the conclusions of this paper (OR, 2.10; 95% CI, 1.63-2.72; I² = 0.5%).

CONCLUSIONS

Our results show that mild hypothermia (33-35 °C) lasting at least 24 h can greatly reduce short-term mortality and significantly improve favorable short-term neurologic outcomes in VA-ECMO-assisted patients without bleeding-related risks. As the grade assessment indicated that the certainty of the evidence was relatively low, hypothermia as a strategy for VA-ECMO-assisted patient care may need to be treated with caution.

Validation of the rCAST Score and Comparison to the PCAC and FOUR Scores for Prognostication after Out-of-Hospital Cardiac Arrest

AIM

Early, accurate outcome prediction after out-of-hospital cardiac arrest (OHCA) is critical for clinical decision-making and resource allocation. We sought to validate the revised post-Cardiac Arrest Syndrome for Therapeutic hypothermia (rCAST) score in a United States cohort and compare its prognostic performance to the Pittsburgh Cardiac Arrest Category (PCAC) and Full Outline of UnResponsiveness (FOUR) scores.

METHODS

This is a single-center, retrospective study of OHCA patients admitted between January 2014-August 2022. Area under the receiver operating curve (AUC) was computed for each score for predicting poor neurologic outcome at discharge and in-hospital mortality. We compared the scores' predictive abilities via Delong's test.

RESULTS

Of 505 OHCA patients with all scores available, the medians [IQR] for rCAST, PCAC, and FOUR scores were 9.5 [6.0, 11.5], 4 [3,4], and 2 [0, 5], respectively. The AUC [95% confidence interval] of the rCAST, PCAC, and FOUR scores for predicting poor neurologic outcome were 0.815 [0.763 - 0.867], 0.753 [0.697 - 0.809], and 0.841 [0.796 - 0.886], respectively. The AUC [95% confidence interval] of the rCAST, PCAC, and FOUR scores for predicting mortality were 0.799 [0.751 - 0.847], 0.723 [0.673 - 0.773], and 0.813 [0.770 - 0.855], respectively. The rCAST score was superior to the PCAC score for predicting mortality (p=0.017). The FOUR score was superior to the PCAC score for predicting poor neurological outcome (p<0.001) and mortality (p<0.001).

CONCLUSION

The rCAST score can reliably predict poor outcome in a United States cohort of OHCA patients regardless of TTM status and outperforms the PCAC score.

Targeted Temperature Management After Out-of-Hospital Cardiac Arrest: Integrating Evidence Into Real World Practice

Targeted temperature management (TTM) after out-of-hospital cardiac arrest (OHCA) has been a focus of debate in an attempt to improve post-arrest outcomes. Contemporary trials examining the role of TTM after cardiac arrest suggest that targeting normothermia should be the standard of care for initially comatose survivors of cardiac arrest. Differences in patient populations have been demonstrated across trials, and important subgroups may be under-represented in clinical trials compared with real-world registries. In this review, we aimed to describe the populations represented in international OHCA registries and to propose a pathway to integrate clinical trial evidence into practice. The patient case mix among registries including survivors to hospital admission was similar to the pivotal trials (shockable rhythm, witnessed arrest), suggesting reasonable external validity. Therefore, for the majority of OHCA, targeted normothermia should be the strategy of choice. There remains conflicting evidence for patients with a nonshockable rhythm, with no clear evidence-based justification for mild hypothermia over targeted normothermia.

Influence of temperature management at 33 °C versus normothermia on survival in patients with vasopressor support after out-of-hospital cardiac arrest: a post hoc analysis of the TTM-2 trial

Background

Targeted temperature management at 33 °C (TTM33) has been employed in effort to mitigate brain injury in unconscious survivors of out-of-hospital cardiac arrest (OHCA). Current guidelines recommend prevention of fever, not excluding TTM33. The main objective of this study was to investigate if TTM33 is associated with mortality in patients with vasopressor support on admission after OHCA.

Methods

We performed a post hoc analysis of patients included in the TTM-2 trial, an international, multicenter trial, investigating outcomes in unconscious adult OHCA patients randomized to TTM33 versus normothermia. Patients were grouped according to level of circulatory support on admission: (1) no-vasopressor support, mean arterial blood pressure (MAP) ≥ 70 mmHg; (2) moderate-vasopressor support MAP < 70 mmHg or any dose of dopamine/dobutamine or noradrenaline/adrenaline dose ≤ 0.25 µg/kg/min; and (3) high-vasopressor support, noradrenaline/adrenaline dose > 0.25 µg/kg/min. Hazard ratios with TTM33 were calculated for all-cause 180-day mortality in these groups.

Results

The TTM-2 trial enrolled 1900 patients. Data on primary outcome were available for 1850 patients, with 662, 896, and 292 patients in the, no-, moderate-, or high-vasopressor support groups, respectively. Hazard ratio for 180-day mortality was 1.04 [98.3% CI 0.78–1.39] in the no-, 1.22 [98.3% CI 0.97–1.53] in the moderate-, and 0.97 [98.3% CI 0.68–1.38] in the high-vasopressor support groups with regard to TTM33. Results were consistent in an imputed, adjusted sensitivity analysis.

Conclusions

In this exploratory analysis, temperature control at 33 °C after OHCA, compared to normothermia, was not associated with higher incidence of death in patients stratified according to vasopressor support on admission.

Trial registration Clinical trials identifier NCT02908308, registered September 20, 2016.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04107-9.

Differential Effect of Targeted Temperature Management Between 32 °C and 36 °C Following Cardiac Arrest According to Initial Severity of Illness: Insights From Two International Data Sets

BACKGROUND

Recent guidelines have emphasized actively avoiding fever to improve outcomes in patients who are comatose following resuscitation from cardiac arrest (ie, out-of-hospital cardiac arrest). However, whether targeted temperature management between 32 °C and 36 °C (TTM32-36) can improve neurologic outcome in some patients remains debated.

RESEARCH QUESTION

Is there an association between the use of TTM32-36 and outcome according to severity assessed at ICU admission using a previously derived risk score?

STUDY DESIGN AND METHODS

Data prospectively collected in the Sudden Death Expertise Center (SDEC) registry (France) between May 2011 and December 2017 and in the Resuscitation Outcomes Consortium Continuous Chest Compressions (ROC-CCC) trial (United States and Canada) between June 2011 and May 2015 were used for this study. Severity at ICU admission was assessed through a modified version of the Cardiac Arrest Hospital Prognosis (mCAHP) score, divided into tertiles of severity. The study explored associations between TTM32-36 and favorable neurologic status at hospital discharge by using multiple logistic regression as well as in tertiles of severity for each data set.

RESULTS

A total of 2,723 patients were analyzed in the SDEC data set and 4,202 patients in the ROC-CCC data set. A favorable neurologic status at hospital discharge occurred in 728 (27%) patients in the French data set and in 1,239 (29%) patients in the North American data set. Among the French data set, TTM32-36 was independently associated with better neurologic outcome in the tertile of patients with low (adjusted OR, 1.63; 95% CI, 1.15-2.30; P = .006) and high (adjusted OR, 1.94; 95% CI, 1.06-3.54; P = .030) severity according to mCAHP at ICU admission. Similar results were observed in the North American data set (adjusted ORs of 1.36 [95% CI, 1.05-1.75; P = .020] and 2.42 [95% CI, 1.38-4.24; P = .002], respectively). No association was observed between TTM32-36 and outcome in the moderate groups of the two data sets.

INTERPRETATION

TTM32-36 was significantly associated with a better outcome in patients with low and high severity at ICU admission assessed according to the mCAHP score. Further studies are needed to evaluate individualized temperature control following out-of-hospital cardiac arrest.

Targeted Temperature Management After Cardiac Arrest: A Systematic Review

Targeted temperature management (TTM) has been the cornerstone of post-cardiac arrest care, but even after therapy, neurological outcomes remain poor. We performed a systematic review to evaluate the influence of TTM in post-cardiac arrest treatment, its effect on the neurological outcome, survival, and the adverse events associated with it. We also aimed to examine any difference between the effect of therapy at various intensities and durations on the prognosis of the patient.

A search of two databases was done to find relevant studies, followed by a thorough screening in which the inclusion and exclusion criteria were applied, and a quality appraisal of clinical trials was done. In this systematic review, six randomized clinical trials with a total of 3870 participants were examined. Of these, 2,767 participants were treated with targeted hypothermia to varying degrees (between 31 and 36 degrees Celsius), 931 participants were treated with targeted normothermia (36.5 to 37.5 degrees Celsius), and 172 participants were treated with only normothermia (without any active cooling or interventions).

It was concluded that TTM at a lower temperature did not have any benefit regarding the neurological outcome and mortality over targeted normothermia but was superior to no temperature management. TTM was also found to have significantly more negative effects when the intensity or duration was increased. 

Differential Effectiveness of Hypothermic Targeted Temperature Management According to the Severity of Post-Cardiac Arrest Syndrome

International guidelines recommend targeted temperature management (TTM) to improve the neurological outcomes in adult patients with post-cardiac arrest syndrome (PCAS). However, it still remains unclear if the lower temperature setting (hypothermic TTM) or higher temperature setting (normothermic TTM) is superior for TTM. According to the most recent large randomized controlled trial (RCT), hypothermic TTM was not found to be associated with superior neurological outcomes than normothermic TTM in PCAS patients. Even though this represents high-quality evidence obtained from a well-designed large RCT, we believe that we still need to continue investigating the potential benefits of hypothermic TTM. In fact, several studies have indicated that the beneficial effect of hypothermic TTM differs according to the severity of PCAS, suggesting that there may be a subgroup of PCAS patients that is especially likely to benefit from hypothermic TTM. Herein, we summarize the results of major RCTs conducted to evaluate the beneficial effects of hypothermic TTM, review the recent literature suggesting the possibility that the therapeutic effect of hypothermic TTM differs according to the severity of PCAS, and discuss the potential of individualized TTM.

Effect of Moderate vs Mild Therapeutic Hypothermia on Mortality and Neurologic Outcomes in Comatose Survivors of Out-of-Hospital Cardiac Arrest: The CAPITAL CHILL Randomized Clinical Trial

IMPORTANCE

Comatose survivors of out-of-hospital cardiac arrest experience high rates of death and severe neurologic injury. Current guidelines recommend targeted temperature management at 32 °C to 36 °C for 24 hours. However, small studies suggest a potential benefit of targeting lower body temperatures.

OBJECTIVE

To determine whether moderate hypothermia (31 °C), compared with mild hypothermia (34 °C), improves clinical outcomes in comatose survivors of out-of-hospital cardiac arrest.

DESIGN, SETTING, AND PARTICIPANTS

Single-center, double-blind, randomized, clinical superiority trial carried out in a tertiary cardiac care center in eastern Ontario, Canada. A total of 389 patients with out-of-hospital cardiac arrest were enrolled between August 4, 2013, and March 20, 2020, with final follow-up on October 15, 2020.

INTERVENTIONS

Patients were randomly assigned to temperature management with a target body temperature of 31 °C (n = 193) or 34 °C (n = 196) for a period of 24 hours.

MAIN OUTCOMES AND MEASURES

The primary outcome was all-cause mortality or poor neurologic outcome at 180 days. Neurologic outcome was assessed using the Disability Rating Scale, with poor neurologic outcome defined as a score greater than 5 (range, 0-29, with 29 being the worst outcome [vegetative state]). There were 19 secondary outcomes, including mortality at 180 days and length of stay in the intensive care unit.

RESULTS

Among 367 patients included in the primary analysis (mean age, 61 years; 69 women [19%]), 366 (99.7%) completed the trial. The primary outcome occurred in 89 of 184 patients (48.4%) in the 31 °C group and in 83 of 183 patients (45.4%) in the 34 °C group (risk difference, 3.0% [95% CI, 7.2%-13.2%]; relative risk, 1.07 [95% CI, 0.86-1.33]; P = .56). Of the 19 secondary outcomes, 18 were not statistically significant. Mortality at 180 days was 43.5% and 41.0% in patients treated with a target temperature of 31 °C and 34 °C, respectively (P = .63). The median length of stay in the intensive care unit was longer in the 31 °C group (10 vs 7 days; P = .004). Among adverse events in the 31 °C group vs the 34 °C group, deep vein thrombosis occurred in 11.4% vs 10.9% and thrombus in the inferior vena cava occurred in 3.8% and 7.7%, respectively.

CONCLUSIONS AND RELEVANCE

In comatose survivors of out-of-hospital cardiac arrest, a target temperature of 31 °C did not significantly reduce the rate of death or poor neurologic outcome at 180 days compared with a target temperature of 34 °C. However, the study may have been underpowered to detect a clinically important difference.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02011568.

Neuromonitoring After Cardiac Arrest: Can Twenty-First Century Medicine Personalize Post Cardiac Arrest Care?

Cardiac arrest survivors comprise a heterogeneous population, in which the etiology of arrest, systemic and neurologic comorbidities, and sequelae of post-cardiac arrest syndrome influence the severity of secondary brain injury. The degree of secondary neurologic injury can be modifiable and is influenced by factors that alter cerebral physiology. Neuromonitoring techniques provide tools for evaluating the evolution of physiologic variables over time. This article reviews the pathophysiology of hypoxic-ischemic brain injury, provides an overview of the neuromonitoring tools available to identify risk profiles for secondary brain injury, and highlights the importance of an individualized approach to post cardiac arrest care.

Which Target Temperature for Post-Anoxic Brain Injury? A Systematic Review from "Real Life" Studies

There is a persistent debate on the optimal target temperature to use during cooling procedures in cardiac arrest survivors. A large randomized clinical trial (RCT) including more than 900 patients showed that targeted temperature management (TTM) at 33 °C had similar mortality and unfavorable neurological outcome (UO) rates as TTM at 36 °C in out-of-hospital cardiac arrest patients with any initial rhythm. Since then, several observational studies have been published on the effects of changes in target temperature (i.e., from 33 to 36 °C) on patients’ outcome. We performed a systematic literature search from 1 January 2014 to 4 December 2020 and identified ten retrospective studies (very low levels of certainty; high risk of bias), including 5509 patients, that evaluated TTM at 33 °C vs. TTM at 36 °C on the occurrence of UO (n = eight studies) and mortality (n = ten studies). TTM at 33 °C was associated with a lower risk of UO when studies assessing neurological outcome with the Cerebral Performance Categories were analyzed (OR 0.80 [95% CIs 0.72–0.98]; p = 0.03). No differences in mortality were observed within the two TTM strategies. These results suggest that an inappropriate translation of TTM protocols from large well-conducted randomized trials into clinical management may result in unexpected effects on patients’ outcome. As for all newly commercialized drugs, epidemiological studies and surveillance programs with an adequate follow-up on large databases are necessary to understand how RCTs are implemented into medical practice.

Post-resuscitation shock: recent advances in pathophysiology and treatment

A post-resuscitation shock occurs in 50–70% of patients who had a cardiac arrest. It is an early and transient complication of the post-resuscitation phase, which frequently leads to multiple-organ failure and high mortality. The pathophysiology of post-resuscitation shock is complex and results from the whole-body ischemia–reperfusion process provoked by the sequence of circulatory arrest, resuscitation manoeuvers and return of spontaneous circulation, combining a myocardial dysfunction and sepsis features, such as vasoplegia, hypovolemia and endothelial dysfunction. Similarly to septic shock, the hemodynamic management of post-resuscitation shock is based on an early and aggressive hemodynamic management, including fluid administration, vasopressors and/or inotropes. Norepinephrine should be considered as the first-line vasopressor in order to avoid arrhythmogenic effects of other catecholamines and dobutamine is the most established inotrope in this situation. Importantly, the optimal mean arterial pressure target during the post-resuscitation shock still remains unknown and may probably vary according to patients. Mechanical circulatory support by extracorporeal membrane oxygenation can be necessary in the most severe patients, when the neurological prognosis is assumed to be favourable. Other symptomatic treatments include protective lung ventilation with a target of normoxia and normocapnia and targeted temperature management by avoiding the lowest temperature targets. Early coronary angiogram and coronary reperfusion must be considered in ST-elevation myocardial infarction (STEMI) patients with preserved neurological prognosis although the timing of coronary angiogram in non-STEMI patients is still a matter of debate. Further clinical research is needed in order to explore new therapeutic opportunities regarding inflammatory, hormonal and vascular dysfunction.

Association of Initial Illness Severity and Outcomes After Cardiac Arrest With Targeted Temperature Management at 36 °C or 33 °C

IMPORTANCE

It is uncertain what the optimal target temperature is for targeted temperature management (TTM) in patients who are comatose following cardiac arrest.

OBJECTIVE

To examine whether illness severity is associated with changes in the association between target temperature and patient outcome.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study compared outcomes for 1319 patients who were comatose after cardiac arrest at a single center in Pittsburgh, Pennsylvania, from January 2010 to December 2018. Initial illness severity was based on coma and organ failure scores, presence of severe cerebral edema, and presence of highly malignant electroencephalogram (EEG) after resuscitation.

EXPOSURE

TTM at 36 °C or 33 °C.

MAIN OUTCOMES AND MEASURES

Primary outcome was survival to hospital discharge, and secondary outcomes were modified Rankin Scale and cerebral performance category.

RESULTS

Among 1319 patients, 728 (55.2%) had TTM at 33 °C (451 [62.0%] men; median [interquartile range] age, 61 [50-72] years) and 591 (44.8%) had TTM at 36 °C (353 [59.7%] men; median [interquartile range] age, 59 [48-69] years). Overall, 184 of 187 patients (98.4%) with severe cerebral edema died and 234 of 243 patients (96.3%) with highly malignant EEG died regardless of TTM strategy. Comparing TTM at 33 °C with TTM at 36 °C in 911 patients (69.1%) with neither severe cerebral edema nor highly malignant EEG, survival was lower in patients with mild to moderate coma and no shock (risk difference, -13.8%; 95% CI, -24.4% to -3.2%) but higher in patients with mild to moderate coma and cardiopulmonary failure (risk difference, 21.8%; 95% CI, 5.4% to 38.2%) or with severe coma (risk difference, 9.7%; 95% CI, 4.0% to 15.3%). Interactions were similar for functional outcomes. Most deaths (633 of 968 [65.4%]) resulted after withdrawal of life-sustaining therapies.

CONCLUSIONS AND RELEVANCE

In this study, TTM at 33 °C was associated with better survival than TTM at 36 °C among patients with the most severe post-cardiac arrest illness but without severe cerebral edema or malignant EEG. However, TTM at 36 °C was associated with better survival among patients with mild- to moderate-severity illness.

D-Lactic Acid as a Metabolite: Toxicology, Diagnosis, and Detection

Two enantiomers of lactic acid exist. While L-lactic acid is a common compound of human metabolism, D-lactic acid is produced by some strains of microorganism or by some less relevant metabolic pathways. While L-lactic acid is an endogenous compound, D-lactic acid is a harmful enantiomer. Exposure to D-lactic acid can happen by various ways including contaminated food and beverages and by microbiota during some pathological states like short bowel syndrome. The exposure to D-lactic acid cannot be diagnosed because the common analytical methods are not suitable for distinguishing between the two enantiomers. In this review, pathways for D-lactic acid, pathological processes, and diagnostical and analytical methods are introduced followed by figures and tables. The current literature is summarized and discussed.

A practical approach to the use of targeted temperature management after cardiac arrest

Among comatose survivors after cardiac arrest, target temperature management (TTM) is considered the most effective treatment to reduce the consequences of postanoxic brain injury. Several international guidelines have thus incorporated TTM in the management of the postresuscitation phase. However, despite extremely promising results in animal models and in randomized trials including selected patient cohorts, TTM benefits on neurological outcome have been questioned. Moreover, TTM potential side effects have raised some concerns on its wide application in all cardiac arrest patients in different healthcare systems. There is indeed still relatively large uncertainty concerning some practical aspects related to TTM application, such as: A) how to select patients who will benefit the most from TTM; B) the optimal time to initiate TTM; C) the best target temperature; D) the most effective methods to provide TTM; E) the length of the cooling phase; and F) the optimal rewarming rate and fever control strategies. The purpose of this manuscript is to review and discuss the most recent advances in TTM use after cardiac arrest and to give some proposals on how to deal with all these relevant practical questions.