Therapeutic hypothermia after cardiac arrest: A systematic review/meta-analysis exploring the impact of expanded criteria and targeted temperature

Influence of Cooling duration on Efficacy in Cardiac Arrest Patients (ICECAP): study protocol for a multicenter, randomized, adaptive allocation clinical trial to identify the optimal duration of induced hypothermia for neuroprotection in comatose, adult survivors of after out-of-hospital cardiac arrest

Background

Cardiac arrest is a common and devastating emergency of both the heart and brain. More than 380,000 patients suffer out-of-hospital cardiac arrest annually in the United States. Induced cooling of comatose patients markedly improved neurological and functional outcomes in pivotal randomized clinical trials, but the optimal duration of therapeutic hypothermia has not yet been established.

Methods

This study is a multi-center randomized, response-adaptive, duration (dose) finding, comparative effectiveness clinical trial with blinded outcome assessment. We investigate two populations of adult comatose survivors of cardiac arrest to ascertain the shortest duration of cooling that provides the maximum treatment effect. The design is based on a statistical model of response as defined by the primary endpoint, a weighted 90-day mRS (modified Rankin Scale, a measure of neurologic disability), across the treatment arms. Subjects will initially be equally randomized between 12, 24, and 48 hours of therapeutic cooling. After the first 200 subjects have been randomized, additional treatment arms between 12 and 48 hours will be opened and patients will be allocated, within each initial cardiac rhythm type (shockable or non-shockable), by response adaptive randomization. As the trial continues, shorter and longer duration arms may be opened. A maximum sample size of 1800 subjects is proposed. Secondary objectives are to characterize: the overall safety and adverse events associated with duration of cooling, the effect on neuropsychological outcomes, and the effect on patient reported quality of life measures.

Discussion

In-vitro and in-vivo studies have shown the neuroprotective effects of therapeutic hypothermia for cardiac arrest. We hypothesize that longer durations of cooling may improve either the proportion of patients that attain a good neurological recovery or may result in better recovery among the proportion already categorized as having a good outcome. If the treatment effect of cooling is increasing across duration, for at least some set of durations, then this provides evidence of the efficacy of cooling itself versus normothermia, even in the absence of a normothermia control arm, confirming previous RCTs for OHCA survivors of shockable rhythms and provides the first prospective controlled evidence of efficacy in those without initial shockable rhythms.

Trial registration

ClinicalTrials.gov (NCT04217551, 2019-12-30).

A Bayesian Interpretation of a Pediatric Cardiac Arrest Trial (THAPCA-OH)

BACKGROUND: Pediatric out-of-hospital cardiac arrest results in high morbidity and mortality. Currently, there are no recommended therapies beyond supportive care. The THAPCA-OH (Therapeutic Hypothermia after Pediatric Cardiac Arrest Out-of-Hospital) trial compared hypothermia (33.0°C) with normothermia (36.8°C) in 295 children. Good neurobehavioral outcome and survival at 1 year were higher in the hypothermia group (20 vs. 12% and 38 vs. 29%, respectively). These differences did not meet the planned statistical threshold of P75% for all informative prior integrations with the THAPCA-OH results, except those with the most pessimistic priors. CONCLUSIONS: There is a high probability that hypothermia provides a modest benefit in neurobehavioral outcome and survival at 1 year. (ClinicalTrials.gov number, NCT00878644.)

Consensus recommendations on therapeutic hypothermia after minimally invasive intracerebral hemorrhage evacuation from the hypothermia for intracerebral hemorrhage (HICH) working group

Background and purpose

Therapeutic hypothermia (TH), or targeted temperature management (TTM), is a classic treatment option for reducing inflammation and potentially other destructive processes across a wide range of pathologies, and has been successfully used in numerous disease states. The ability for TH to improve neurological outcomes seems promising for inflammatory injuries but has yet to demonstrate clinical benefit in the intracerebral hemorrhage (ICH) patient population. Minimally invasive ICH evacuation also presents a promising option for ICH treatment with strong preclinical data but has yet to demonstrate functional improvement in large randomized trials. The biochemical mechanisms of action of ICH evacuation and TH appear to be synergistic, and thus combining hematoma evacuation with cooling therapy could provide synergistic benefits. The purpose of this working group was to develop consensus recommendations on optimal clinical trial design and outcomes for the use of therapeutic hypothermia in ICH in conjunction with minimally invasive ICH evacuation.

Methods

An international panel of experts on the intersection of critical-care TH and ICH was convened to analyze available evidence and form a consensus on critical elements of a focal cooling protocol and clinical trial design. Three focused sessions and three full-group meetings were held virtually from December 2020 to February 2021. Each meeting focused on a specific subtopic, allowing for guided, open discussion.

Results

These recommendations detail key elements of a clinical cooling protocol and an outline for the roll-out of clinical trials to test and validate the use of TH in conjunction with hematoma evacuation as well as late-stage protocols to improve the cooling approach. The combined use of systemic normothermia and localized moderate (33.5°C) hypothermia was identified as the most promising treatment strategy.

Conclusions

These recommendations provide a general outline for the use of TH after minimally invasive ICH evacuation. More research is needed to further refine the use and combination of these promising treatment paradigms for this patient population.

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.

Association of time-temperature curves with outcomes in temperature management for cardiac arrest

Background/Purpose

Cardiac arrest is a common cause of death and neurological injury; therapeutic cooling for neuroprotection is standard of care. Despite numerous and ongoing trials targeting a specified cooling temperature for a target duration, the concept of temperature dose—the duration spent at a given depth of hypothermia—is not as well explored.

Methods

In this retrospective study, we examined 66 patients 18 years of age or older undergoing therapeutic hypothermia for cardiac arrest between 2007 and 2010 to assess the relationship of temperature dose with outcomes. Demographic, clinical, outcome and temperature data were collected. Demographic and clinical data underwent bivariate regression analysis for association with outcome. Time-temperature curves were divided into pre-determined temperature thresholds and assessed by logistic regression analysis for association with outcome. A second, multivariate regression analysis was performed controlling for factors associated with poor outcomes.

Results

Old age was significantly associated with poor outcome and a shockable arrest rhythm was significantly associated with positive outcome. Subjects spent an average of 2.82 hours below 35°C, 7.31 hours ≥35°C to ≤36.5°C, 24.75 hours >36.5 to <38.0°C and 7.06 hours ≥38°C. Logistic regression analysis revealed borderline significant positive association between good outcome and time at a cooling depth (35°C–36.5°C, p=0.05); adjusted for old age, the association became significant (p=0.04).

Conclusion

Controlling for old age, longer durations between >35°C, ≤36.5°C during therapeutic hypothermia for cardiac arrest were significantly associated with good clinical outcomes. Time spent within a given temperature range may be useful for measuring the effect of temperature management.

Temperature Management in the ICU

OBJECTIVE

Temperature abnormalities are recognized as a marker of human disease, and the therapeutic value of temperature is an attractive treatment target. The objective of this synthetic review is to summarize and critically appraise evidence for active temperature management in critically ill patients.

DATA SOURCES

We searched MEDLINE for publications relevant to body temperature management (including targeted temperature management and antipyretic therapy) in cardiac arrest, acute ischemic and hemorrhagic stroke, traumatic brain injury, and sepsis. Bibliographies of included articles were also searched to identify additional relevant studies.

STUDY SELECTION

English-language systematic reviews, meta-analyses, randomized trials, observational studies, and nonhuman data were reviewed, with a focus on the most recent randomized control trial evidence.

DATA EXTRACTION

Data regarding study methodology, patient population, temperature management strategy, and clinical outcomes were qualitatively assessed.

DATA SYNTHESIS

Temperature management is common in critically ill patients, and multiple large trials have been conducted to elucidate temperature targets, management strategies, and timing. The strongest data concerning the use of therapeutic hypothermia exist in comatose survivors of cardiac arrest, and recent trials suggest that appropriate postarrest temperature targets between 33°C and 37.5°C are reasonable. Targeted temperature management in other critical illnesses, including acute stroke, traumatic brain injury, and sepsis, has not shown benefit in large clinical trials. Likewise, trials of pharmacologic antipyretic therapy have not demonstrated improved outcomes, although national guidelines do recommend treatment of fever in patients with stroke and traumatic brain injury based on observational evidence associating fever with worse outcomes.

CONCLUSIONS

Body temperature management in critically ill patients remains an appealing therapy for several illnesses, and additional studies are needed to clarify management strategies and therapeutic pathways.

Target temperature management following cardiac arrest: a systematic review and Bayesian meta-analysis

Background

Temperature control with target temperature management (TTM) after cardiac arrest has been endorsed by expert societies and adopted in international clinical practice guidelines but recent evidence challenges the use of hypothermic TTM.

Methods

Systematic review and Bayesian meta-analysis of clinical trials on adult survivors from cardiac arrest undergoing TTM for at least 12 h comparing TTM versus no TTM or with a separation > 2 °C between intervention and control groups using the PubMed/MEDLINE, EMBASE, CENTRAL databases from inception to 1 September 2021 (PROSPERO CRD42021248140). All randomised and quasi-randomised controlled trials were considered. The risk ratio and 95% confidence interval for death (primary outcome) and unfavourable neurological recovery (secondary outcome) were captured using the original study definitions censored up to 180 days after cardiac arrest. Bias was assessed using the updated Cochrane risk-of-bias for randomised trials tool and certainty of evidence assessed using the Grading of Recommendation Assessment, Development and Evaluation methodology. A hierarchical robust Bayesian model-averaged meta-analysis was performed using both minimally informative and data-driven priors and reported by mean risk ratio (RR) and its 95% credible interval (95% CrI).

Results

In seven studies (three low bias, three intermediate bias, one high bias, very low to low certainty) recruiting 3792 patients the RR by TTM 32–34 °C was 0.95 [95% CrI 0.78—1.09] for death and RR 0.93 [95% CrI 0.84—1.02] for unfavourable neurological outcome. The posterior probability for no benefit (RR ≥ 1) by TTM 32–34 °C was 24% for death and 12% for unfavourable neurological outcome. The posterior probabilities for favourable treatment effects of TTM 32–34 °C were the highest for an absolute risk reduction of 2–4% for death (28–53% chance) and unfavourable neurological outcome (63–78% chance). Excluding four studies without active avoidance of fever in the control arm reduced the probability to achieve an absolute risk reduction > 2% for death or unfavourable neurological outcome to ≤ 50%.

Conclusions

The posterior probability distributions did not support the use of TTM at 32–34 °C compared to 36 °C also including active control of fever to reduce the risk of death and unfavourable neurological outcome at 90–180 days. Any likely benefit of hypothermic TTM is smaller than targeted in RCTs to date.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03935-z.

An Overview of Therapy Guidelines for Cardiac Arrest and the Potential Benefits of Hemoglobin-Based Oxygen Carriers

Currently, there is an unmet therapeutic need for the medical management of cardiac arrest, as is evident from the high mortality rate associated with this condition. These dire outcomes can be attributed to the severe nature and poor prognosis of this disorder. However, the current treatment modalities, while helping to augment survival, are limited and do not offer adequate improvements to outcomes. Treatment modalities are particularly lacking when considering the underlying pathophysiology of the metabolic phase of cardiac arrest. In this study, we explore the three phases of cardiac arrest and assess the factors related to positive clinical outcomes and survival for these events. Furthermore, we evaluate the present guidelines for resuscitation and recovery, the issues related to ischemia and tissue reperfusion, and the benefit of oxygen-delivery therapeutic methods including blood transfusion therapy and synthetic hemoglobins (HBOCs). The current therapy protocols are limited specifically by the lack of an efficient method of oxygen delivery to address the metabolic phase of cardiac arrest. In this article, we investigate the next generation of HBOCs and review their properties that make them attractive for their potential application in the treatment of cardiac arrest. These products may be a viable solution to address complications associated with ischemia, reperfusion injury, and organ damage.

Increasing the Effectiveness of Targeted Temperature Management

TOPIC

Targeted temperature management and therapeutic hypothermia are essential components of the multimodal approach to caring for compromised patients after cardiac arrest and severe traumatic brain injury.

CLINICAL RELEVANCE

The continuously evolving science necessitates summation of individual facets and concepts to enhance knowledge and application for optimally delivering care. Targeted temperature management is a complex therapy that requires fine-tuning the most effective interventions to maintain high-quality targeted temperature management and maximize patient outcomes.

PURPOSE

To describe the underlying pathophysiology of fever and the importance of manipulating water temperature and of preventing and treating shivering during that process.

CONTENT COVERED

This article discusses nursing considerations regarding the care of patients requiring targeted temperature management that are necessary to improve patient outcomes.

Cerebrospinal fluid is a significant fluid source for anoxic cerebral oedema

Cerebral edema develops after anoxic brain injury. In two models of asphyxial and asystolic cardiac arrest without resuscitation, we found that edema develops shortly after anoxia secondary to terminal depolarizations and the abnormal entry of cerebrospinal fluid (CSF). Edema severity correlated with the availability of CSF with the age-dependent increase in CSF volume worsening the severity of edema. Edema was identified primarily in brain regions bordering CSF compartments in mice and humans. The degree of ex vivo tissue swelling was predicted by an osmotic model suggesting that anoxic brain tissue possesses a high intrinsic osmotic potential. This osmotic process was temperature-dependent, proposing an additional mechanism for the beneficial effect of therapeutic hypothermia. These observations show that CSF is a primary source of edema fluid in anoxic brain. This novel insight offers a mechanistic basis for the future development of alternative strategies to prevent cerebral edema formation after cardiac arrest.

Predicting the survivals and favorable neurologic outcomes after targeted temperature management by artificial neural networks

BACKGROUND

To identify the outcome-associated predictors and develop predictive models for patients receiving targeted temperature management (TTM) by artificial neural network (ANN).

METHODS

The derived cohort consisted of 580 patients with cardiac arrest and ROSC treated with TTM between January 2014 and August 2019. We evaluated the predictive value of parameters associated with survival and favorable neurologic outcome. ANN were applied for developing outcome prediction models. The generalizability of the models was assessed through 5-fold cross-validation. The performance of the models was assessed according to the accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC).

RESULTS

The parameters associated with survival were age, duration of cardiopulmonary resuscitation, history of diabetes mellitus (DM), heart failure, end-stage renal disease (ESRD), systolic blood pressure (BP), diastolic BP, body temperature, motor response after ROSC, emergent coronary angiography or percutaneous coronary intervention (PCI), and the cooling methods. The parameters associated with the favorable neurologic outcomes were age, sex, DM, chronic obstructive pulmonary disease, ESRD, stroke, pre-arrest cerebral-performance category, BP, body temperature, motor response after ROSC, emergent coronary angiography or PCI, and cooling methods. After adequate training, ANN Model 1 to predict survival achieved an AUC of 0.80. Accuracy, sensitivity, and specificity were 75.9%, 71.6%, and 79.3%, respectively. ANN Model 4 to predict the favorable neurologic outcome achieved an AUC of 0.87, with accuracy, sensitivity, and specificity of 86.7%, 77.7%, and 88.0%, respectively.

CONCLUSIONS

The ANN-based models achieved good performance to predict the survival and favorable neurologic outcomes after TTM. The models proposed have clinical value to assist in decision-making.

Skin sympathetic nerve activity as a biomarker for neurologic recovery during therapeutic hypothermia for cardiac arrest

BACKGROUND

Targeted temperature management (TTM) improves neurologic outcome after cardiac arrest. However, better neurologic prognostication is needed.

OBJECTIVE

The purpose of this study was to test the hypothesis that noninvasive recording of skin sympathetic nerve activity (SKNA) and its association with heart rate (HR) during TTM may serve as a biomarker of neurologic status.

METHODS

SKNA recordings were analyzed from 29 patients undergoing TTM. Patients were grouped based on Clinical Performance Category (CPC) score into group 1 (CPC 1-2) representing a good neurologic outcome and group 2 (CPC 3-5) representing a poor neurologic outcome.

RESULTS

Of the 29 study participants, 18 (62%) were deemed to have poor neurologic outcome. At all timepoints, low average skin sympathetic nerve activity (aSKNA) was associated with poor neurologic outcome (odds ratio 22.69; P = .002) and remained significant (P = .03) even when adjusting for presenting clinical factors. The changes in aSKNA and HR during warming in group 1 were significantly correlated (ρ = 0.49; P <.001), even when adjusting for corresponding temperature and mean arterial pressure measurements (P = .017), whereas this correlation was not observed in group 2. Corresponding to high aSKNA, there was increased nerve burst activity during warming in group 1 compared to group 2 (0.739 ± 0.451 vs 0.176 ± 0.231; P = .013).

CONCLUSION

Neurologic recovery was retrospectively associated with SKNA. Patients undergoing TTM who did not achieve neurologic recovery were associated with low SKNA and lacked a significant correlation between SKNA and HR. These preliminary results indicate that SKNA may potentially be a useful biomarker to predict neurologic status in patients undergoing TTM.

Therapeutic Hypothermia With Progesterone Improves Neurologic Outcomes in Ventricular Fibrillation Cardiac Arrest After Electric Shock

Trauma by electricity imposes mechanical, electrical, and thermal forces on the human body. Often, the delicate cardiac electrophysiology is disrupted causing dysrhythmia and subsequent cardiac arrest. Anoxic brain injury (ABI) is the most severe consequence and the main cause of mortality following cardiac arrest. Establishing a working protocol to treat patients who are at risk for ABI after suffering a cardiac arrest is of paramount importance. There has yet to be sufficient exploration of combination therapy of therapeutic hypothermia (TH) and progesterone as a neuroprotective strategy in patients who have suffered cardiac arrest after electric shock.

The protocol required TH initiation upon transfer to the ICU with a target core body temperature of 33°C for 18 hours. This was achieved through a combination of cooling blankets, ice packs, chilled IV fluids, nasogastric lavage with iced saline, and intravascular cooling devices. Progesterone therapy at 80-100 mg intramuscularly every 12 hours for 72 hours was initiated shortly after admission to the ICU.

We present a case series of three patients (mean age = 29.3 years, mean presenting Glasgow Coma Score = 3) who suffered ventricular fibrillation (VF) cardiac arrest from non-lightning electric shock, and who had considerably improved outcomes following the TH-progesterone combination therapy protocol. The average length of stay was 13.7 days.

The cases presented suggest that there may be a role for neuroprotective combination therapy in post-resuscitation care of VF cardiac arrest. While TH is well documented as a neuroprotective measure, progesterone administration is a safe therapy with promising, albeit currently inconclusive, neuroprotective effect. Future protocols involving TH and progesterone combination therapy in these patients should be further explored.

Increasing the shockable rhythm and survival rate by dispatcher-assisted cardiopulmonary resuscitation in Japan

Purpose

This study aimed to examine the effectiveness of cardiopulmonary resuscitation (CPR) directions by dispatchers. We analysed the relationship of dispatcher-assisted bystander cardiopulmonary resuscitation (DA-BCPR) with favourable cerebral function, shockable rhythm rate, and emergency medical service (EMS) arrival time.

Methods

This nationwide study was based on CPR statistical data of out-of-hospital cardiac arrest (OHCA) patients (n = 629,471) from 1 January 2011 to 31 December 2015, and included 107,669 patients with bystander-witnessed cardiogenic cardiac arrest.The primary outcome was good brain function prognosis after 1 month, while the secondary outcome was the rate of shockable rhythm on ECG at the time of EMS arrival.EMS arrival time at the site was stratified into 7 min, 8-10 min, and 11-20 min using tertiles. Adjusted odds ratios (AORs) and 95% confidence intervals (95% CIs) were estimated using multivariate logistic regression analysis to assess the association between DA-BCPR and outcomes in each tertile.

Results

There were 37,269 (35%), 18,109 (17%), and 52,291 (49%) patients in the DA-BCPR, Only-BCPR, and no-BCPR groups, respectively. Compared to No-BCPR, DA-BCPR was associated with favourable neurological outcomes regardless of the time from 119 call to EMS contact (AOR, 1.56, 2.01, 1.82; 95% CI, 1.43-1.71, 1.80-2.24, 1.52-2.19; ≤7 min, 8-10 min, and 11-20 min, respectively). DA-BCPR showed association with the shockable rhythm rate upon EMS arrival regardless of the time 119 call to EMS contact (AOR, 1.30, 1.60, 1.90; 95% CI, 1.23-1.38, 1.51-1.70, 1.75-2.06; ≤7 min, 8-10 min, and 11-20 min, respectively).

Conclusion

Providing dispatcher assistance with CPR to 119 callers improves the long-term outcome regardless of the patient's age and EMS response time. Thus, encouraging dispatchers to promote BCPR is important for increasing the shockable rhythm rate and improving the brain function prognosis.

European Resuscitation Council Guidelines 2021: Epidemiology of cardiac arrest in Europe

In this section of the European Resuscitation Council Guidelines 2021, key information on the epidemiology and outcome of in and out of hospital cardiac arrest are presented. Key contributions from the European Registry of Cardiac Arrest (EuReCa) collaboration are highlighted. Recommendations are presented to enable health systems to develop registries as a platform for quality improvement and to inform health system planning and responses to cardiac arrest.

QT interval dynamics and triggers for QT prolongation immediately following cardiac arrest

BACKGROUND

The prolongation in QT interval typically observed following cardiac arrest is considered to be multifactorial and induced by external triggers such as hypothermia therapy and exposure to antiarrhythmic medications.

OBJECTIVE

To evaluate the corrected QT interval (QTc) dynamics in the first 10 days following cardiac arrest with respect to the etiology of arrest, hypothermia and QT prolonging medications.

METHODS

We enrolled 104 adult survivors of cardiac arrest, where daily ECG was available for at least 3 days. We followed their QT and QRS intervals for the first 10 days of hospitalization. We used both Bazett and Fridericia formulas to correct for heart rate. For patients with QRS < 120 we analyzed the QTc interval (n = 90) and for patients with QRS > 120 ms we analyzed the JTc (n = 104) vs. including only the narrow QRS samples (n = 89). We stratified patients by 3 groups: (1) presence of ischemic heart disease (IHD) (2) treatment with hypothermia protocol, and (3) treatment with QTc prolonging medications. Additionally, genetic information obtained during hospitalization was analyzed.

RESULTS

QTc and JTc intervals were significantly prolonged in the first 6 days. Maximal QTc/JTc prolongation was observed in day 2 (QTcB = 497 ± 55). There were no differences in daily QTc/JTc and QRS intervals in the first 2 days post arrest between patients with or without hypothermia induction but such difference was found with QT prolonging medications. All subgroups demonstrated significantly prolonged QTc/JTc interval regardless of the presence of IHD, hypothermia protocol or QTc prolonging medication exposure. Our results were consistent for both Bazetts' and Frediricia correction and for any QRS duration. Prolongation of the JTcB beyond 382 ms after day 3 predicted sustained QTc/JTc prolongation beyond day 6 with an ROC of 0.78.

CONCLUSIONS

QTc/JTc interval is significantly and independently prolonged post SCA, regardless of known QT prolonging triggers. Normalization of the QTc post cardiac arrest should be expected only after day 6 of hospitalization. Assessment of the QTc for adjudication of the etiology of arrest or for monitoring the effect of QT prolonging medications may be unreliable.

Choosing Neuroanaesthesia as a career: Marching towards new horizons

Anaesthesiology is an ever-changing science and amongst its sub-specialities, the field of neuroanaesthesia is making rapid strides. The fragility of the brain and spinal cord and the multitude of complexities involved in neurosurgery and interventional neuroradiological procedures demand dedicated training in neuroanaesthesia. With rapid advancement in other neuroscience specialties, neuroanaesthesia too has made outstanding progress, owing to establishment of structured training, publication of high-quality scientific research, and invention of novel medications and monitoring modalities. The opportunities for training in India and abroad and resources to broaden knowledge in neuroanaesthesia have increased over the last two decades. A career in neuroanaesthesia offers a great future for budding anaesthesiologists.

Review of Hypothermia Protocol and Timing of the Echocardiogram

Targeted temperature management, also known as therapeutic hypothermia (TH), is recommended for out-of-hospital cardiac arrest (OHCA). Both internal or external methods of cooling can be applied. Individuals resuscitated from OHCA frequently develop postarrest myocardial dysfunction resulting in decreased cardiac output and left ventricular systolic function. This dysfunction is usually transient and improves with spontaneous recovery over time. Echocardiogram (ECHO) can be a vital tool for the assessment and management of these patients. This manuscript reviewed methods available for TH after OHCA and reviews role of ECHO in the diagnosis and prognosis in this setting.

The Role of Hypothermia in Large Hemispheric Infarction: A Systematic Review and Meta-Analysis

Background: Hypothermia is used in the treatment of large hemispheric infarction (LHI); however, its role in outcomes for LHI patients remains ambiguous. This systematic review and meta-analysis was conducted to evaluate the effect of hypothermia on the outcomes of LHI patients. Methods: We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, China Biological Medicine Database, and clinical trials registers before September 21, 2018, and then scanned the reference lists. Randomized controlled trials that compared hypothermia with normothermia in LHI patients were included. Primary outcomes that we reviewed were mortality and neurological outcome. Adverse events during treatment were defined as secondary outcomes. We performed a meta-analysis to calculate pooled risk ratios (RRs), standardized mean differences (SMDs), and 95% confidence intervals (CIs) using fixed-effect models. Results: Three randomized controlled trials involving 131 participants were included. No statistically significant association was revealed between hypothermia and mortality (RR, 1.12; 95% CI, 0.76-1.65). There was significant association between hypothermia and good neurological outcome as assessed by modified Rankin Scale score (mRS of 0-3) of survivors (RR, 2.09; 95% CI, 1.14-3.82), and with neurological outcome by mRS (SMD, -0.54; 95% CI, -1.07 to -0.01). However, significant associations were found between hypothermia and gastrointestinal bleeding, gastric retention, electrolyte derangement, and shivering. No significant differences were detected in the incidence of developing herniation in the rewarming process, pneumonia, cardiac arrhythmia, hemorrhagic transformation, hyperglycemia, hypotension, acute kidney injury, and venous thrombotic events in LHI patients who underwent hypothermia compared with those who had normothermia. Conclusions: This meta-analysis suggested that hypothermia was not associated with mortality in LHI patients. However, it was associated with the improvement of neurological outcome, but with a higher risk of adverse events during treatment. Future studies are needed to demonstrate the efficacy and safety of hypothermia for LHI. The protocol for this systematic review was obtained from PROSPERO (registration number: CRD42018111761).

Meta-Analysis of the Usefulness of Therapeutic Hypothermia After Cardiac Arrest

Despite current guidelines recommending therapeutic hypothermia (TH) for post cardiac arrest comatose patient, its use remains limited. Randomized controlled trials (RCTs) have also reported conflicting results on the efficacy of TH. Therefore, we conducted an updated meta-analysis to evaluate the effect of TH in post cardiac arrest patients. We searched electronic databases for RCTs comparing TH (32°C to 34°C) with controls (normothermia or temperature ≥36°C) in comatose patients who sustained cardiac arrest. Mortality and neurological outcomes were the outcomes of interest. We used random effect meta-analysis to estimate risk ratio (RR) with 95% confidence interval (CI). Eight RCTs with a total of 2,026 patients (TH n = 1,025 and control n = 1,001) were included. Irrespective of initial rhythm, TH was associated with significant reduction in poor neurological outcomes (RR 0.87, 95% CI 0.77 to 0.98; p = 0.02) without any difference in mortality (RR 0.94, 95% CI 0.85 to 1.03; p = 0.17). In patients with initial shockable rhythm compared with control, TH reduced mortality (RR 0.85, 95% CI 0.73 to 0.99; p = 0.04) and poor neurological outcomes (RR 0.81, 95% CI 0.67 to 0.99; p = 0.04). Whereas, in patients with initial nonshockable rhythm, TH was associated with decreased poor neurological outcomes after excluding one trial (RR 0.95 95% CI 0.91 to 1.00; p = 0.05). In conclusion, TH is associated with improved neurological outcomes in all patients sustaining cardiac arrest and with decreased mortality in patients with initial shockable rhythm.

Neurologic prognostication after resuscitation from cardiac arrest

Out-of-hospital cardiac arrest remains a leading cause of mortality in the United States, and the majority of patients who die after achieving return of spontaneous circulation die from withdrawal of care due to a perceived poor neurologic prognosis. Unfortunately, withdrawal of care often occurs during the first day of admission and research suggests this early withdrawal of care may be premature and result in unnecessary deaths for patients who would have made a full neurologic recovery. In this review, we explore the evidence for neurologic prognostication in the emergency department for patients who achieve return of spontaneous circulation after an out-of-hospital cardiac arrest.

Is Procalcitonin a Marker of Neurologic Outcome or Early Infection in Patients Treated with Targeted Temperature Management?

Objectives

Although high procalcitonin (PCT) levels are associated with poor neurological outcomes and increased mortality rates in patients treated with targeted temperature management (TTM) in the postcardiac arrest (CA) period, there are limited data about the correlation between PCT levels and infection. The aim of our study was to assess the relationship of PCT levels in the first 48 hours with early period infections, late period neurological prognosis, and mortality in patients treated with TTM after CA.

Materials and methods

Serum PCT was measured on admission days 1 and 2. The early onset infection diagnosis before the seventh day in the intensive care unit (ICU) was made according to the criteria of infection centers for disease control and prevention. Mortality and neurologic outcomes were assessed 90 days after CA according to cerebral performance category (CPC) score.

Results

There was no statistically significant correlation between early period infection diagnosis and PCT levels at the time of admission, 24th, and 48th hours. Patients with poor neurologic outcomes on the 90th day had significantly high PCT levels at 24 (p = 0.044) and 48 hours (p = 0.004). There was no statistically significant correlation between admission PCT levels and neurological prognosis. While the correlation between mortality and PCT levels at 24 (p = 0.049) and 48 (p = 0.004) hours was significantly high, no statistically significant correlation was found between admission PCT levels and mortality.

Conclusion

In patients treated with TTM after CA, increased PCT levels were significantly correlated with poor neurologic outcomes and mortality. However, the elevated PCT levels were not significantly correlated with early period infections.

How to cite this article

Zincircioglu C, Yavuz T, Sarıtaş A, Çakmak M, Güldoğan IK, Uzun U, et al. Is Procalcitonin a Marker of Neurologic Outcome or Early Infection in Patients Treated with Targeted Temperature Management? Indian J Crit Care Med 2020;24(5):327–331.

Sustaining improvement of dispatcher-assisted cardiopulmonary resuscitation for out-of-hospital cardiac arrest patients in Japan: An observational study

Objectives

We aimed to estimate the relationship between the promotion of bystander cardiopulmonary resuscitation (CPR) with dispatcher-assistance over time and good cerebral function after out-of-hospital cardiac arrests (OHCAs).

Methods

This was a retrospective observational study, using a nationwide OHCA database in Japan. The eligible 267,193 witnessed cardiogenic OHCA patients between 2005 and 2016 were analysed. Multivariable logistic regression models were performed to estimate the effect of dispatcher-assisted bystander CPR per year. In addition, we calculated the number of patients with good cerebral function, which was attributed to dispatcher-assisted bystander CPR.

Results

Dispatcher-assisted bystander CPR was performed to 84,076 (31.5%), those without dispatcher-assistance were 48,389 (18.1%), and non-bystander CPR were 134,728 (50.4%). The adjusted odds ratio (AOR) of dispatcher-assisted bystander CPR vs. non-bystander CPR was significantly related to good cerebral function, regardless of the year (AOR, 1.47, 1.62; 95%CI, 1.19-1.80, 1.42-1.85, 2005 and 2016, respectively). The association of dispatcher-assisted bystander CPR with good cerebral function tended to increase (AOR, 1.11, 2.97; 95%CI, 0.99-1.24, 2.69-3.28, 2006 and 2016, based on 2005, respectively). Estimating the number of patients with good cerebral function who attributed to dispatcher-assisted bystander CPR was a significant increase from 41 in 2005 to 580 in 2016 (p < .0001, r = 0.98). Furthermore, chest compression consistently contributed to higher number of patients with good cerebral function than that with a combination of chest compression and shock with public-access-defibrillation.

Conclusion

We found that the increased dispatcher-assisted bystander CPR rate was related to good cerebral function at 1-month post OHCA. Chest compression without public-access-defibrillation was most helpful to that number, explaining the effects of dispatcher-assistance and sustaining improvement.

[Preclinical management of cardiac arrest-extracorporeal cardiopulmonary resuscitation]

BACKGROUND

The chances of surviving out-of-hospital cardiac arrest (OHCA) are still very low. Despite intensive efforts the outcome has remained relatively poor over many years. In specific situations, new technologies, such as extracorporeal cardiopulmonary resuscitation (eCPR) could significantly improve survival with a good neurological outcome.

OBJECTIVE

Does the immediate restoration of circulation and reoxygenation via eCPR influence the survival rate after OHCA? Is eCPR the new link in the chain of survival?

MATERIAL AND METHODS

Discussion of current study results and guideline recommendations.

RESULTS

The overall survival rates after OHCA have remained at 10-30% over many years. Despite low case numbers more recent retrospective studies showed that an improved outcome can be achieved with eCPR. In selected patient collectives survival with a favorable neurological outcome is possible in 38% of the cases.

CONCLUSION

Survival after cardiac arrest and the subsequent quality of life dependent on many different factors. The time factor, i.e. the avoidance of a no-flow phase and reduction of the low-flow phase is of fundamental importance. The immediate restoration of the circulation and oxygen supply by eCPR can significantly improve survival; however, large randomized, controlled trials are currently not available.

State-of-the-art considerations in post-arrest care

Cardiac arrest has a high rate of morbidity and mortality. Several advances in post-cardiac arrest management can improve outcome, but are time-dependent, placing the emergency physician in a critical role to both recognize the need for and initiate therapy. We present a novel perspective of both the workup and therapeutic interventions geared toward the emergency physician during the first few hours of care. We describe how the immediate care of a post-cardiac arrest patient is resource intensive and requires simultaneous evaluation for the underlying cause and intensive management to prevent further end organ damage, particularly of the central nervous system. The goal of the initial focused assessment is to rapidly determine if any reversible causes of cardiac arrest are present and to intervene when possible. Interventions performed in this acute period are aimed at preventing additional brain injury through optimizing hemodynamics, providing ventilatory support, and by using therapeutic hypothermia when indicated. After the initial phase of care, disposition is guided by available resources and the clinician's judgment. Transfer to a specialized cardiac arrest center is prudent in centers that do not have significant support or experience in the care of these patients.

A nationwide overview of 1-year mortality in cardiac arrest patients admitted to intensive care units in the Netherlands between 2010 and 2016

AIM

Worldwide, cardiac arrest (CA) remains a major cause of death. Most post-CA patients are admitted to the intensive care unit (ICU). The aim of this study is to describe mortality rates and possible changes in mortality rates in patients with CA admitted to the ICU in the Netherlands between 2010 and 2016.

METHODS

In this study, we included all adult CA patients registered in the National Intensive Care Evaluation (NICE) registry who were admitted to ICUs in the Netherlands between 2010 and 2016. The primary outcome was 1-year mortality which was analysed by Cox regression. The secondary outcomes were ICU mortality and hospital mortality. Hospital mortality was analysed by binary logistic regression analysis. Patients were stratified by whether they experienced in-hospital cardiac arrest (IHCA) or out-of-hospital cardiac arrest (OHCA). Finally, the outcome over calendar time was assessed for both groups.

RESULTS

We included 26,056 CA patients: 10,618 (40.8%) IHCA patients and 14,482 (55.6%) OHCA patients. The 1-year mortality rate was 57.5%: 59% for IHCA and 56.4% for OHCA, p < 0.01. This mortality rate remained stable between 2010 and 2016 for IHCA (p = 0.31) and declined for OHCA patients (p = 0.01). The hospital mortality rate was 50.3%: 50.5% for IHCA and 50.2% for OHCA, p = 0.66. This mortality rate remained stable between 2010-2016 for IHCA (p = 0.21) and decreased for OHCA patients (p < 0.01). An additional analysis with calendar year as a continuous variable showed a mortality decline of 1.56% per calendar year for 1-year mortality.

CONCLUSION

This nationwide registry cohort study reported a 57.5% 1-year mortality rate for CA patients admitted to the ICU between 2010 and 2016. We reported a decline in 1-year mortality for OHCA patients in these years.

Geographical Differences and the National Meeting Effect in Patients with Out-of-Hospital Cardiac Arrests: A JCS-ReSS Study Report

The "national meeting effect" refers to worse patient outcomes when medical professionals attend academic meetings and hospitals have reduced staffing. The aim of this study was to examine differences in outcomes of patients with out-of-hospital cardiac arrest (OHCA) admitted during, before, and after meeting days according to meeting location and considering regional variation of outcomes, which has not been investigated in previous studies. Using data from a nationwide, prospective, population-based, observational study in Japan, we analyzed adult OHCA patients who underwent resuscitation attempts between 2011 and 2015. Favorable one-month neurological outcomes were compared among patients admitted during the relevant annual meeting dates of three national scientific societies, those admitted on identical days the week before, and those one week after the meeting dates. We developed a multivariate logistic regression model after adjusting for confounding factors, including meeting location and regional variation (better vs. worse outcome areas), using the "during meeting days" group as the reference. A total of 40,849 patients were included in the study, with 14,490, 13,518, and 12,841 patients hospitalized during, before, and after meeting days, respectively. The rates of favorable neurological outcomes during, before, and after meeting days was 1.7, 1.6, and 1.8%, respectively. After adjusting for covariates, favorable neurological outcomes did not differ among the three groups (adjusted OR (95% CI) of the before and after meeting dates groups was 1.03 (0.83-1.28) and 1.01 (0.81-1.26), respectively. The "national meeting effect" did not exist in OHCA patients in Japan, even after comparing data during, before, and after meeting dates and considering meeting location and regional variation.

Quality of physician care coordination during inter-facility transfer for cardiac arrest patients

AIM

We sought to evaluate whether the quality of coordination between physicians transferring comatose cardiac arrest survivors to a high-volume cardiac arrest center for targeted temperature management (TTM) was associated with timeliness of care.

METHODS

We conducted a retrospective analysis of inter-facility transfers to Vanderbilt University Medical Center for TTM between October 2016 and October 2018. We examined the relationship between Relational Coordination (RC) - a measure of communication and relationship quality - during phone conversations between transferring physicians and time-to-acceptance.

RESULTS

We identified 18 patients meeting criteria. TTM was initiated or continued in 72%, and in-hospital mortality was 75%. Median time-to-acceptance was 2.77 (interquartile range [IQR] 2.0, 4.1) minutes, and duration of calls was 3.95 (IQR 2.7, 5.2) minutes. Interrater reliability for overall RC was high (rho = 0.87). The correlation between RC and the time-to-acceptance was significant in univariate analyses (adjusted relative risk = 0.96, 95%CI 0.93, 1.0, p = 0.05). Secondary analyses did not find a significant relationship between RC and timeliness measures.

CONCLUSION

In this sample of patients transferred for TTM, we found that RC as a measure of care coordination, was reliable. Higher quality care coordination for cardiac arrest survivors was associated with faster physician acceptance. Future work using a larger cohort should explore if higher RC among a broader set of stakeholders (physicians, EMS, families, etc.) is associated with timeliness measures after adjusting for other factors, to better understand how the quality of care coordination impacts timeliness of care and patient outcomes.

Variation in survival after out-of-hospital cardiac arrest between receiving hospitals in Japan: an observational study

OBJECTIVES

Patient outcomes after out-of-hospital cardiac arrest (OHCA) varies at multilevel (geographical regions, emergency medical service agencies and receiving hospitals) in the USA. However, it remains unclear whether there is a variation in patient outcomes after OHCA between relevant units of the healthcare system such as receiving hospitals in Japan. Therefore, we aimed to quantify the variation in patient outcomes after OHCA between receiving hospitals in Japan.

DESIGN

Secondary analysis of the prospective multicentre OHCA registry.

SETTING

The Japan Association for Acute Medicine OHCA Registry, a prospective multicentre OHCA registry, including 73 medical institutions in Japan.

PARTICIPANTS

9303 adults (≥18 years old) with OHCA of medical origin, treated at 67 hospitals from June 2014 to December 2015.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was 1-month survival after OHCA. The secondary outcome was favourable functional status at 1 month, defined as cerebral performance category scale 1 or 2. We constructed a series of multivariable hierarchical logistic regression models predicting outcomes, accounting for patient-level variables and clustering of patients within hospitals. We evaluated the adjusted 1-month survival and functional outcome for each hospital, ranked hospitals for each outcome and calculated median ORs (MORs) to quantify the between-hospital variation in outcomes.

RESULTS

The prevalence of 1-month survival after OHCA was 7.1% (663/9303) and that of favourable functional outcome was 3.6% (331/9303). After adjustment for patient-level factors, we observed variations in 1-month survival (range, 1.6%-13.8%; adjusted MOR 1.34; 95% CI 1.16 to 1.67) and favourable functional outcome (range, 0.7%-7.3%; adjusted MOR 1.53; 95% CI 1.10 to 2.24) between hospitals.

CONCLUSIONS

We found substantial variations in patient outcomes after OHCA within a large group of hospitals in Japan, despite adjustment for patient factors that are known to be associated with different outcomes.

The Effect of Prehospital Epinephrine in Out-of-Hospital Cardiac Arrest: A Systematic Review and Meta-Analysis

INTRODUCTION

Epinephrine has been recommended for out-of-hospital cardiac arrest (OHCA) resuscitation for nearly one century, but its efficacy and safety remain unclear in the literature. The primary aim of this review was to determine whether epinephrine increases the return of spontaneous circulation in OHCA patients.

METHODS

A systematic review and meta-analysis were conducted using the following databases: MEDLINE, EMBASE, and CENTRAL, from their inception until October 2018. All the randomized controlled trials (RCTs) were included. Observational studies, case reports, case series, and non-systematic reviews were excluded.

RESULTS

Two trials including 8,548 patients were eligible for inclusion in the data synthesis. In patients who received epinephrine during OHCA, the incidence of return of spontaneous circulation was increased, with an odds ratio (95%CI) of 4.25 (3.79-4.75), P <.001, high-quality of evidence. The number of patients transported to hospital was increased in patients who had prehospital epinephrine, with an odds ratio (95%CI) of 2.31 (2.11-2.53), P <.001, high-quality of evidence. The prehospital use of epinephrine was associated with an increased survival to hospital discharge, the odds ratio (95%CI) being 1.43 (1.10-1.87), P = .008, moderate-quality of evidence. No significant effect was noted on the favorable neurologic state of patient at hospital discharge, with an odds ratio (95%CI) of 1.21 (0.90-1.64), P = .21, moderate-quality of evidence.

CONCLUSIONS

This meta-analysis suggests that the prehospital use of epinephrine increases return of spontaneous circulation, transport of patients to hospital, and survival to hospital discharge for OHCA. However, no significant effects on favorable neurologic function at hospital discharge were demonstrated. The general quality of evidence ranged from moderate to high.

Cerebral Edema After Cardiopulmonary Resuscitation: A Therapeutic Target Following Cardiac Arrest?

We sought to review the role that cerebral edema plays in neurologic outcome following cardiac arrest, to understand whether cerebral edema might be an appropriate therapeutic target for neuroprotection in patients who survive cardiopulmonary resuscitation. Articles indexed in PubMed and written in English. Following cardiac arrest, cerebral edema is a cardinal feature of brain injury and is a powerful prognosticator of neurologic outcome. Like other conditions characterized by cerebral ischemia/reperfusion, neuroprotection after cardiac arrest has proven to be difficult to achieve. Neuroprotection after cardiac arrest generally has focused on protecting neurons, not the microvascular endothelium or blood-brain barrier. Limited preclinical data suggest that strategies to reduce cerebral edema may improve neurologic outcome. Ongoing research will be necessary to determine whether targeting cerebral edema will improve patient outcomes after cardiac arrest.

An evolutionary perspective on immunometabolism

Metabolism is at the core of all biological functions. Anabolic metabolism uses building blocks that are either derived from nutrients or synthesized de novo to produce the biological infrastructure, whereas catabolic metabolism generates energy to fuel all biological processes. Distinct metabolic programs are required to support different biological functions. Thus, recent studies have revealed how signals regulating cell quiescence, proliferation, and differentiation also induce the appropriate metabolic programs. In particular, a wealth of new studies in the field of immunometabolism has unveiled many examples of the connection among metabolism, cell fate decisions, and organismal physiology. We discuss these findings under a unifying framework derived from the evolutionary and ecological principles of life history theory.

Impact of hypothermia on cardiac performance during targeted temperature management after cardiac arrest

INTRODUCTION

Targeted temperature management (TTM) is a well-accepted neuro-protective intervention in the management of comatose survivors of cardiac arrest (CA). However, the impact of TTM on cardiac performance has not been adequately evaluated.

METHODS

We reviewed data on consecutive CA survivors undergoing TTM at a quaternary cardiac intensive care unit between January 2015 and June 2017. Enrollment was restricted to cases with invasive hemodynamics (iHDs) at TTM initiation, every 8 h at target temperature (32-34 °C) and at completion of rewarming (>36 °C), unless precluded by mortality. Cardiac index and cardiac index-derived variables were adjusted for a decreased oxygen consumption during hypothermia. We assessed the serial impact of cooling on iHDs and cardiac performance utilizing longitudinal data analysis accounting for the effects of time as surrogate for the expected change from the post arrest syndrome and instituted treatments. A Frank-Starling construct was used to evaluate changes in cardiac contractility.

RESULTS

We evaluated the effects of cooling on iHDs and cardiac performance in 46 CA survivors. Heart rate decreased with cooling (p < 0.001), to return to baseline after rewarming (p = 0.6). Mean arterial pressure and pulmonary wedge pressure decreased by cooling (p < 0.001 for both), with sustained improvement after rewarming (p < 0.001 for both). Systemic vascular resistance was unaffected by hypothermia (p > 0.05). Left stroke work index increased with cooling (p < 0.001), with return to baseline after rewarming (p = 0.6). Cooling was associated with a left-upward shift in the Frank-Starling curve indicative of increased contractility.

CONCLUSION

Mild hypothermia in CA survivors appears associated to positive changes in iHDs and cardiac performance, including a potential increase in cardiac contractility. Larger studies are needed to conclusively confirm these findings.

The post-cardiac arrest syndrome: A case for lung-brain coupling and opportunities for neuroprotection

Systemic inflammation and multi-organ failure represent hallmarks of the post-cardiac arrest syndrome (PCAS) and predict severe neurological injury and often fatal outcomes. Current interventions for cardiac arrest focus on the reversal of precipitating cardiac pathologies and the implementation of supportive measures with the goal of limiting damage to at-risk tissue. Despite the widespread use of targeted temperature management, there remain no proven approaches to manage reperfusion injury in the period following the return of spontaneous circulation. Recent evidence has implicated the lung as a moderator of systemic inflammation following remote somatic injury in part through effects on innate immune priming. In this review, we explore concepts related to lung-dependent innate immune priming and its potential role in PCAS. Specifically, we propose and investigate the conceptual model of lung-brain coupling drawing from the broader literature connecting tissue damage and acute lung injury with cerebral reperfusion injury. Subsequently, we consider the role that interventions designed to short-circuit lung-dependent immune priming might play in improving patient outcomes following cardiac arrest and possibly other acute neurological injuries.

Door-to-Targeted Temperature Management Initiation After Out-of-Hospital Cardiac Arrest: A New Quality Metric in Postresuscitation Care?

See Article Stanger et al

Invasive Hemodynamics and Outcomes in Cardiac Arrest Survivors Undergoing Targeted Temperature Management

Most important prognostic factors in the postcardiac arrest patients who underwent targeted temperature management (TTM) derive from the periarrest period. Whether early invasive hemodynamics predict survival or neurologic outcomes remains unknown. We retrospectively reviewed all comatose survivors of cardiac arrest who underwent TTM at the Coronary Intensive Care Unit of a Quaternary Center between January 2015 and June 2017. Patients were required to have a set of invasive hemodynamics available at initiation of TTM to be included. Those with cooling initiated before admission and temperature of <36°C before obtaining hemodynamics were excluded. Univariate logistic and multivariate regression were conducted to test whether cardiac index (Fick-cardiac index ≥2.2 vs <2.2 L/min/m²), pulmonary capillary wedge pressure (PCWP ≥18 vs <18 mm Hg), systemic vascular resistance (SVR >1200 vs 800 to 1200 vs <800 dynes⋅s/cm⁵) or Forrester hemodynamic profiles were predictive of survival and favorable neurologic outcomes at hospital discharge. Total of 52 consecutive arrest survivors who underwent TTM were studied demonstrating a wide variability in invasive hemodynamic parameters. There was no association between cardiac index (p = 0.45 and p = 0.10), PCWP (p = 0.90 and p = 0.60), SVR (0.95 and p = 0.17) or Forrester hemodynamic profiles (p = 0.40 and p = 0.42) and survival or favorable neurologic outcome at discharge. In conclusion, comatose arrest survivors who underwent TTM presents with a wide spectrum of invasive hemodynamics highlighting the heterogeneity of the postcardiac arrest syndrome. Early invasive hemodynamics did not predict survival or favorable neurologic outcomes at hospital discharge.

Effect of cooling on lung secretory phospholipase A2 activity in vitro, ex vivo, and in vivo

Hypothermia can modify surfactant composition and function. Secretory phospholipase A2 (sPLA2) hydrolyses surfactant phospholipids and is important in the pathobiology of several critical respiratory disorders. We hypothesize that sPLA2 activity might be influenced by the temperature partially explaining surfactant changes. This study aims to evaluate comprehensively the effect of hypothermia on sPLA2 activity. We measured sPLA2 activity at different temperatures, alone or combined with bile acids, in vitro (incubating human recombinant sPLA2-IIA and porcine sPLA2-IB), ex vivo (by cooling bronchoalveolar lavage samples from neonates with respiratory distress syndrome or no lung disease), and in vivo (using lavage samples obtained before and after 72 h of whole body cooling in neonates with hypoxic-ischemic encephalopathy). We also measured concentrations of various sPLA2 subtypes and natural sPLA2 inhibitors in in vivo cooled samples. Results were corrected for protein content and dilution. In vitro cooling did not show any effect of hypothermia on sPLA2. Ex vivo cooling did not alter total sPLA2 activity, and the addition of bile acids increased sPLA2 activity irrespective of the temperature and the type of sampled patient. In vivo hypothermia reduced median sPLA2 activity from 16.6 [15.2–106.7] IU/mg to 3.3 [2.7–8.5] IU/mg ( P = 0.026) and mean sPLA2-IIA from 1.1 (0.8) pg/μg to 0.6 (0.4) pg/μg ( P = 0.047), whereas dioleylphosphatidylglycerol increased from 8.3 (3.9)% to 12.8 (5.1)% ( P = 0.02). Whole body hypothermia decreases in vivo global sPLA2 activity in bronchoalveolar lavage fluids through the reduction of sPLA2-IIA and increment of dioleylphosphatidylglycerol. This effect is absent during in vitro or ex vivo hypothermia.

Programmed Cell Death after Intracerebral Hemorrhage

Background:

Intracerebral hemorrhage (ICH) accounts for up to 15% of all strokes and is characterized by high rates of mortality and morbidity. The post-ICH brain injury can be distinguished in 1) primary, which are caused by disrup-tion and mechanical deformation of brain tissue due to hematoma growth and 2) secondary, which are induced by microglia activation, mitochondrial dysfunction, neurotransmitter and inflammatory mediator release. Although these events typically lead to necrosis, the occurrence of programmed cell death has also been reported after ICH.

Methods:

We reviewed recent publications describing advance in pre- and clinic ICH research.

Results:

At present, treatment of ICH patients is based on oral anticoagulant reversal, management of blood pressure and other medical complications. Several pre-clinical studies showed promising results and demonstrated that anti-oxidative and anti-inflammatory treatments reduced neuronal cell death, however, to date, all of these attempts have failed in randomized controlled clinical trials. Yet, the time frame of administration may be crucial in translation from animal to clinical studies. Furthermore, the latest pre-clinical research points toward the existence of other, apoptosis-unrelated forms kinds of pro-grammed cell death.

Conclusion:

Our review summarizes current knowledge of pathways leading to programmed cell death after ICH in addition to data from clinical trials. Some of the pre-clinical results have not yet demonstrated clinical confirmation, however they sig-nificantly contribute to our understanding of post-ICH pathology and can contribute to development of new therapeutic ap-proaches, decreasing mortality and improving ICH patients’ quality of life.

Cardiac arrest by inhalation of deodorant spray

Drug abuse by inhalation of volatile household product substances is uncommon, however, it can have devastating consequences. This case report describes the fatal outcome of deodorant inhalation by a 19-year-old patient in a detoxification clinic who developed a cardiac arrest after inhaling butane from a deodorant spray. Despite initial successful resuscitation, he developed a postanoxic encephalopathy with a status epilepticus resistant to extensive treatment. Inhalant abuse can be a cause of death in young patients.

Differential effect of mild therapeutic hypothermia depending on the findings of hypoxic encephalopathy on early CT images in patients with post-cardiac arrest syndrome

INTRODUCTION

The aim of this study was to evaluate the differential effects of mild therapeutic hypothermia (MTH) in post-cardiac arrest syndrome (PCAS) patients depending on the presence/absence of hypoxic encephalopathy (HE) in the early brain CT images obtained before the initiation of MTH.

METHODS

We conducted a retrospective review of the data of a total of 129 patients with PCAS who were treated by MTH (34 °C) or normothermia treatment (NT) (35 °C or 36 °C), and had undergone brain CT examination prior to the initiation of these treatments. We divided the subjects into 4 groups, namely, the HE(-)/MTH, HE(-)/NT, HE(+)/MTH, and HE(+)/NT groups, for evaluating the interaction effect between the two variables. Then, we compared the neurological outcomes between the HE(-)/MTH and HE(-)/NT groups by multivariate logistic analysis. Good outcome was defined as a Cerebral Performance Category score of ≤2 at 30 days.

RESULTS

The percentages of subjects with a good outcome in the HE(-)/MTH and HE(-)/NT group were 68.9% (42/61) and 36.1% (13/36), respectively (p = .003), while those in the HE(+)/MTH and HE(+)/NT groups were lower, at 7.4% (2/27) and 20.0% (1/5), respectively (p = .410), suggesting a statistically significant interaction effect between the two variables (p_interaction = 0.002). In the HE(-) group, MTH was associated with a higher odds ratio of a good outcome as compared to NT (OR 6.80, 95% CI 1.19-38.96, p = .031).

CONCLUSIONS

The effect of MTH in patients with PCAS differed depending on the presence/absence of evidence of HE on the early CT images.

Novel dry cryotherapy system for cooling the equine digit

Objectives

Digital cryotherapy is commonly used for laminitis prophylaxis and treatment. Currently validated methods for distal limb cryotherapy involve wet application or compression technology. There is a need for a practical, affordable, dry cryotherapy method that effectively cools the digit. The objective of this study was to evaluate the hoof wall surface temperatures (HWSTs) achieved with a novel dry cryotherapy technology.

Design

Repeated-measures in vivo experimental study.

Setting

Experimental intervention at a single site.

Participants

6 systemically healthy horses (3 mares, 3 geldings).

Interventions

Cryotherapy was applied to six horses for eight hours with a commercially available rubber and rubber and welded fabricice boot, which extended proximally to include the foot and pastern. Reusable malleable cold therapy packs were secured against the foot and pastern with the three built-in hook-and-loop fastener panels.

Primary and secondary outcome measures

HWST and pastern surface temperature of the cryotherapy-treated limb, HWST of the control limb and ambient temperature were recorded every five minutes throughout the study period.

Results

Results were analysed with mixed-effects multivariable regression analysis. The HWST (median 11.1°C, interquartile range 8.6°C–14.7°C) in the cryotherapy-treated limb was significantly decreased compared with the control limb (median 29.7°C, interquartile range 28.9°C–30.4°C) (P≤0.001). Cryotherapy limb HWST reached a minimum of 6.75°C (median) with an interquartile range of 4.1°C–9.3°C. Minimum HWST was achieved 68 minutes after cryotherapy pack application.

Conclusions

Dry application of cryotherapy significantly reduced HWST and reached minimums below the therapeutic target of 10°C. This cryotherapy method might offer an effective alternative for digital cooling.