Hyperthermia after cardiac arrest is associated with an unfavorable neurologic outcome

Time to start of cardiopulmonary resuscitation and the effect of target temperature management at 33°C and 36°C

INTRODUCTION

The optimal temperature during targeted temperature management (TTM) for comatose patients resuscitated from out-of-hospital cardiac arrest is unknown. It has been hypothesized that patients with long no-flow times, for example those without bystander CPR would have the most to gain from temperature management at lower temperatures.

METHODS

We analysed data from an international clinical trial randomizing cardiac arrest patients to targeted temperature management at 33°C and 36°C for an interaction between no-flow time and intervention group, with neurological function at six months after cardiac arrest as the primary outcome. A cerebral performance category (CPC) score of 1 or 2 was considered a good outcome.

RESULTS

No-flow time (min) was associated with poor neurological outcome (OR 1.13, 95% confidence interval 1.06-1.20, p<0.001). There was no statistically significant interaction between no flow-time and intervention group (p=0.11), which may imply that the non-superior effect of 33°C was consistent for all no-flow times. Bystander CPR was not independently associated with neurological function.

CONCLUSIONS

TTM at 33°C compared to 36°C was not associated with an increased probability of a good neurological function for patients with longer no-flow times.

Predictive value of interleukin-6 in post-cardiac arrest patients treated with targeted temperature management at 33 °C or 36 °C

AIM

Post-cardiac arrest syndrome (PCAS) is characterized by systemic inflammation, however data on the prognostic value of inflammatory markers is sparse. We sought to investigate the importance of systemic inflammation, assessed by interleukin-6 (IL-6) in comatose survivors of out-of-hospital cardiac arrest.

METHODS

A total of 682 patients enrolled in the Target Temperature Management (TTM) trial, surviving >24h with available IL-6 data were included. IL-6 was measured on days 1, 2 and 3 after return of spontaneous circulation. Severity of PCAS was assessed daily by the Sequential Organ Failure Assessment score. Survival status was recorded at 30 days.

RESULTS

High levels of IL-6 at day 1-3 (all p<0.0001) were independently associated with severity of PCAS with no interaction of target temperature (all p=NS). IL-6 levels did not differ between temperature groups (p(interaction)=0.99). IL-6 levels at day 2 (p<0.0001) and day 3 (p<0.0001) were associated with crude mortality. Adjusted Cox proportional-hazards analysis showed that a two-fold increase of IL-6 levels at day 2 (HR=1.15 (95% CI: 1.07-1.23), p=0.0002) and day 3 (HR=1.18 (95% CI: 1.09-1.27), p<0.0001) were associated with mortality. IL-6 levels at day 3 had the highest discriminative value in predicting mortality (AUC=0.66). IL-6 did not significantly improve 30-day mortality prediction compared to traditional prognostic factors (p=0.08).

CONCLUSIONS

In patients surviving >24h following cardiac arrest, IL-6 levels were significantly elevated and associated with severity of PCAS with no significant influence of target temperature. High IL-6 levels were associated with increased mortality. Measuring levels of IL-6 did not provide incremental prognostic value.

Temperature Management After Cardiac Arrest: An Advisory Statement by the Advanced Life Support Task Force of the International Liaison Committee on Resuscitation and the American Heart Association Emergency Cardiovascular Care Committee and the Council on Cardiopulmonary, Critical Care, Perioperative and Resuscitation

For more than a decade, mild induced hypothermia (32 °C-34 °C) has been standard of care for patients remaining comatose after resuscitation from out-of-hospital cardiac arrest with an initial shockable rhythm, and this has been extrapolated to survivors of cardiac arrest with initially nonshockable rhythms and to patients with in-hospital cardiac arrest. Two randomized trials published in 2002 reported a survival and neurological benefit with mild induced hypothermia. One recent randomized trial reported similar outcomes in patients treated with targeted temperature management at either 33 °C or 36 °C. In response to these new data, the International Liaison Committee on Resuscitation Advanced Life Support Task Force performed a systematic review to evaluate 3 key questions: (1) Should mild induced hypothermia (or some form of targeted temperature management) be used in comatose post-cardiac arrest patients? (2) If used, what is the ideal timing of the intervention? (3) If used, what is the ideal duration of the intervention? The task force used Grading of Recommendations Assessment, Development and Evaluation methodology to assess and summarize the evidence and to provide a consensus on science statement and treatment recommendations. The task force recommends targeted temperature management for adults with out-of-hospital cardiac arrest with an initial shockable rhythm at a constant temperature between 32 °C and 36 °C for at least 24 hours. Similar suggestions are made for out-of-hospital cardiac arrest with a nonshockable rhythm and in-hospital cardiac arrest. The task force recommends against prehospital cooling with rapid infusion of large volumes of cold intravenous fluid. Additional and specific recommendations are provided in the document.

What is the proper target temperature for out-of-hospital cardiac arrest?

The implementation of target temperature management (TTM) or therapeutic hypothermia has been demonstrated in several major studies to be an effective neuroprotective strategy in postresuscitation care after cardiac arrest. Although several landmark studies found the promising results of lower targeted temperature (32-34 °C) in terms of survival and neurological outcomes, recent evidence showed no difference in either survival or long-term neurological outcome when compared with higher targeted temperature (36 °C). Thus, recent data suggest that avoiding hyperpyrexia, rather than cooling "per se," may be considered the main therapeutic target to avoid secondary brain damage after out-of-hospital cardiac arrest. Many questions are still debated about the exact protocol of TTM to be used, including whether temperature control is more beneficial than standard of care without active temperature control, the optimal cooling temperature, patient selection, and duration of cooling. The aim of this review article was to discuss the physiology of hypothermia, available cooling methods, and current evidence about the optimal target temperature and timing of hypothermia.

Periarrest intestinal bacterial translocation and resuscitation outcome

During the periarrest period, intestinal ischemia may result in barrier dysfunction and bacterial translocation, which has clear mechanistic links to inflammation and cascade stimulation, especially in patients who are treated with therapeutic hypothermia. Despite optimal management, periarrest bacterial translocation may worsen the outcome of cardiac arrest victims.

Hyperthermia aggravates status epilepticus-induced epileptogenesis and neuronal loss in immature rats

This study tightly controlled seizure duration and severity during status epilepticus (SE) in postnatal day 10 (P10) rats, in order to isolate hyperthermia as the main variable and to study its consequences. Body temperature was maintained at 39 ± 1 °C in hyperthermic SE rats (HT+SE) or at 35 ± 1 °C in normothermic SE animals (NT+SE) during 30 min of SE, which was induced by lithium-pilocarpine (3 mEq/kg, 60 mg/kg) and terminated by diazepam and cooling to NT. All video/EEG measures of SE severity were similar between HT+SE and NT+SE pups. At 24h, neuronal injury was present in the amygdala in the HT+SE group only, and was far more severe in the hippocampus in HT+SE than NT+SE pups. Separate groups of animals were monitored four months later for spontaneous recurrent seizures (SRS). Only HT+SE animals developed convulsive SRS. Both HT+SE and NT+SE animals developed electrographic SRS (83% vs. 55%), but SRS frequency and severity were higher in hyperthermic animals (12.5 ± 3.5 vs. 4.2 ± 2.0 SRS/day). The density of hilar neurons was lower, thickness of the amygdala and perirhinal cortex was reduced, and lateral ventricles were enlarged in HT+SE over NT+SE littermates and HT/NT controls. In this model, hyperthermia greatly increased the epileptogenicity of SE and its neuropathological sequelae.

Therapeutic hypothermia after out-of-hospital cardiac arrest in children

BACKGROUND

Therapeutic hypothermia is recommended for comatose adults after witnessed out-of-hospital cardiac arrest, but data about this intervention in children are limited.

METHODS

We conducted this trial of two targeted temperature interventions at 38 children's hospitals involving children who remained unconscious after out-of-hospital cardiac arrest. Within 6 hours after the return of circulation, comatose patients who were older than 2 days and younger than 18 years of age were randomly assigned to therapeutic hypothermia (target temperature, 33.0°C) or therapeutic normothermia (target temperature, 36.8°C). The primary efficacy outcome, survival at 12 months after cardiac arrest with a Vineland Adaptive Behavior Scales, second edition (VABS-II), score of 70 or higher (on a scale from 20 to 160, with higher scores indicating better function), was evaluated among patients with a VABS-II score of at least 70 before cardiac arrest.

RESULTS

A total of 295 patients underwent randomization. Among the 260 patients with data that could be evaluated and who had a VABS-II score of at least 70 before cardiac arrest, there was no significant difference in the primary outcome between the hypothermia group and the normothermia group (20% vs. 12%; relative likelihood, 1.54; 95% confidence interval [CI], 0.86 to 2.76; P=0.14). Among all the patients with data that could be evaluated, the change in the VABS-II score from baseline to 12 months was not significantly different (P=0.13) and 1-year survival was similar (38% in the hypothermia group vs. 29% in the normothermia group; relative likelihood, 1.29; 95% CI, 0.93 to 1.79; P=0.13). The groups had similar incidences of infection and serious arrhythmias, as well as similar use of blood products and 28-day mortality.

CONCLUSIONS

In comatose children who survived out-of-hospital cardiac arrest, therapeutic hypothermia, as compared with therapeutic normothermia, did not confer a significant benefit in survival with a good functional outcome at 1 year. (Funded by the National Heart, Lung, and Blood Institute and others; THAPCA-OH ClinicalTrials.gov number, NCT00878644.).

Interpreting the results of the targeted temperature management trial in cardiac arrest

The targeted temperature management (TTM) trial, which found that cooling to 33°C after witnessed cardiac arrest (CA) conferred no benefits compared with 36°C, has led to much debate in the hypothermia community. This article discusses what lessons can be drawn. The TTM trial achieved far better outcomes in controls than any previous randomized controlled trial (RCT) or any nonrandomized study where no fever control was applied. On the other hand, rates of good outcomes in the hypothermia group were somewhat lower than in previous RCTs and most nonrandomized studies. The TTM authors conclude that benefits of temperature management are derived exclusively from fever control and that further lowering of temperature confers no benefit. Indeed, without doubt, the TTM trial demonstrates the crucial importance of strict fever control after CA and that this provides sufficient neuroprotection for some patients. However, we argue that the hypothermia intervention was executed suboptimally (possibly inadvertent selection bias; late start of cooling, up to 4 hours after ROSC; slow cooling rates, 10 hours to target temperature; more rapid rewarming than previous studies; and some other issues). This could explain high rates of good outcomes in controls and lower-than-expected rates in patients cooled to 33°C compared with previous randomized and nonrandomized studies. Outside of two previous RCTs, the use of hypothermia after CA is supported by hundreds of animal experiments, evidence from 46 before-after studies and large registries, and indirect supporting evidence from 7 RCTs in newborns with neonatal asphyxia. In addition, one RCT found improved outcomes with 32°C compared with 34°C. It remains to be explained why the TTM results so completely contradict previous studies in this field. These issues should be thoroughly discussed before changes in guidelines and protocols are made. Ending or modifying hypothermia treatment after CA should require the strongest possible evidence.

Cooling techniques for targeted temperature management post-cardiac arrest

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2015 and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/annualupdate2015. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Targeted Temperature Management in Pediatric Central Nervous System Disease

Acute central nervous system conditions due to hypoxic-ischemic encephalopathy, traumatic brain injury (TBI), status epilepticus, and central nervous system infection/inflammation, are a leading cause of death and disability in childhood. There is a critical need for effective neuroprotective therapies to improve outcome targeting distinct disease pathology. Fever, defined as patient temperature > 38°C, has been clearly shown to exacerbate brain injury. Therapeutic hypothermia (HT) is an intervention using targeted temperature management that has multiple mechanisms of action and robust evidence of efficacy in multiple experimental models of brain injury. Prospective clinical evidence for its neuroprotective efficacy exists in narrowly-defined populations with hypoxic-ischemic injury outside of the pediatric age range while trials comparing hypothermia to normothermia after TBI have failed to demonstrate a benefit on outcome but consistently demonstrate potential use in decreasing refractory intracranial pressure. Data in children from prospective, randomized controlled trials using different strategies of targeted temperature management for various outcomes are few but a large study examining HT versus controlled normothermia to improve neurological outcome in cardiac arrest is underway.

Safety, feasibility, and outcomes of induced hypothermia therapy following in-hospital cardiac arrest-evaluation of a large prospective registry*

OBJECTIVES

Despite a lack of randomized trials, practice guidelines recommend that mild induced hypothermia be considered for comatose survivors of in-hospital cardiac arrest. This study describes the safety, feasibility, and outcomes of mild induced hypothermia treatment following in-hospital cardiac arrest.

DESIGN

Prospective, observational, registry-based study.

SETTING

Forty-six critical care facilities in eight countries in Europe and the United States reporting in the Hypothermia Network Registry and the International Cardiac Arrest Registry.

PATIENTS

A total of 663 patients with in-hospital cardiac arrest and treated with mild induced hypothermia were included between January 2004 and February 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A cerebral performance category of 1 or 2 was considered a good outcome. At hospital discharge 41% of patients had a good outcome. At median 6-month follow-up, 34% had a good outcome. Among in-hospital deaths, 52% were of cardiac causes and 44% of cerebral cause. A higher initial body temperature was associated with reduced odds of a good outcome (odds ratio, 0.79; 95% CI, 0.68-0.92). Adverse events were common; bleeding requiring transfusion (odds ratio, 0.56; 95% CI, 0.31-1.00) and sepsis (odds ratio, 0.52; 95% CI, 0.30-0.91) were associated with reduced odds for a good outcome.

CONCLUSIONS

In this registry study of an in-hospital cardiac arrest population treated with mild induced hypothermia, we found a 41% good outcome at hospital discharge and 34% at follow-up. Infectious complications occurred in 43% of cases, and 11% of patients required a transfusion for bleeding. The majority of deaths were of cardiac origin.

Minor Changes in Core Temperature Prior to Cardiac Arrest Influence Outcomes: An Experimental Study

AIM

To investigate whether slight variations in core temperature prior to cardiac arrest (CA) influence short-term outcomes and mitochondrial functions.

METHODS AND MATERIALS

Three groups of New Zealand White rabbits (n = 12/group) were submitted to 15 minutes of CA at 38°C (T-38 group), 39°C (T-39), or 40°C (T 40) and 120 minutes of reperfusion. A Sham-operated group (n = 6) underwent only surgery. Restoration of spontaneous circulation (ROSC), survival, hemodynamics, and pupillary reactivity were recorded. Animals surviving to the end of the observation period were euthanized to assess fresh brain and heart mitochondrial functions (permeability transition and oxidative phosphorylation). Markers of brain and heart damages were also measured.

RESULTS

The duration of asphyxia required to induce CA was significantly lower in the T-40 group when compared to the T-38 group (P < .05). The rate of ROSC was >80% in all groups (P = nonsignificant [ns]). Survival significantly differed among the T-38, T-39, and T-40 groups: 10 (83%) of 12, 7 (58%) of 12, and 4 (33%) of 12, respectively (log-rank test, P = .027). At the end of the protocol, none of the animals in the T-40 group had pupillary reflexes compared to 8 (67%) of 12 in the T-38 group (P < .05). Troponin and protein S100B were significantly higher in the T-40 versus T-38 group (P < .05). Cardiac arrest significantly impaired both inner mitochondrial membrane integrity and oxidative phosphorylation in all groups. Brain mitochondria disorders were significantly more severe in the T-40 group compared to the T-38 group (P < .05).

CONCLUSION

Small changes in body temperature prior to asphyxial CA significantly influence brain mitochondrial functions and short-term outcomes in rabbits.

Fever and therapeutic normothermia in severe brain injury: an update

PURPOSE OF REVIEW

Fever is common in the ICU among patients with severe brain injury. Fever has been consistently shown to exacerbate brain injuries in animal models and has been consistently associated with poor outcome in human studies. However, whether fever control improves outcome and the ideal means of fever control remain unknown. This review will address recent literature on the impact of fever on severe brain injury and on interventions to maintain normothermia.

RECENT FINDINGS

Current guidelines generally recommend maintenance of normothermia after brain injury but have scant recommendations on methods to do this. Observational trials have continued to demonstrate the association between fever and poor outcome after severe brain injury. Recent trials have shown the efficacy of more aggressive approaches to fever reduction, whereas a large randomized trial showed the relative ineffectiveness of acetaminophen alone for fever control. Several studies have also described the impact of fever and of fever control on brain physiology.

SUMMARY

The value of therapeutic normothermia in the neurocritical care unit (NCCU) is increasingly accepted, yet prospective trials that demonstrate a functional benefit to patients are lacking.

Enhancing approaches to therapeutic hypothermia in patients with sudden circulatory arrest

Cardiac arrest is common and causes substantial morbidity and mortality. Despite advances in prevention and resuscitation, most patients remain unconscious and survival remains poor. Therapeutic hypothermia (32-34 °C) has emerged as a potent neuroprotective modality following resuscitation. In early clinical trials, application of therapeutic hypothermia improved survival in patients with ventricular fibrillation (VF), which led to the recommended use of therapeutic hypothermia for patients resuscitated from VF. However, two recent clinical trials have challenged some assumptions. First, the use of paramedic-initiated rapid infusion of cold crystalloids as a mean to achieve faster cooling rates after resuscitation in patients with and without VF arrest did not improve survival. Second, once patients were admitted to the hospital, targeting their temperature to 33 versus 36 °C for 36 h (in addition to active hyperthermia prevention) after out-of-hospital cardiac arrest did not to change clinical outcomes, suggesting that 36 °C may represent the target temperature instead of temperatures of less than 34 °C.

Cardiac arrest patients have an impaired immune response, which is not influenced by induced hypothermia

INTRODUCTION

Induced hypothermia is increasingly applied as a therapeutic intervention in ICUs. One of the underlying mechanisms of the beneficial effects of hypothermia is proposed to be reduction of the inflammatory response. However, a fear of reducing the inflammatory response is an increased infection risk. Therefore, we studied the effect of induced hypothermia on immune response after cardiac arrest.

METHODS

A prospective observational cohort study in a mixed surgical-medical ICU. Patients admitted at the ICU after surviving cardiac arrest were included and during 24 hours body temperature was strictly regulated at 33°C or 36°C. Blood was drawn at three time points: after reaching target temperature, at the end of the target temperature protocol and after rewarming to 37°C. Plasma cytokine levels and response of blood leucocytes to stimulation with toll-like receptor (TLR) ligands lipopolysaccharide (LPS) from Gram-negative bacteria and lipoteicoic acid (LTA) from Gram-positive bacteria were measured. Also, monocyte HLA-DR expression was determined.

RESULTS

In total, 20 patients were enrolled in the study. Compared to healthy controls, cardiac arrest patients kept at 36°C (n = 9) had increased plasma cytokines levels, which was not apparent in patients kept at 33°C (n = 11). Immune response to TLR ligands in patients after cardiac arrest was generally reduced and associated with lower HLA-DR expression. Patients kept at 33°C had preserved ability of immune cells to respond to LPS and LTA compared to patients kept at 36°C. These differences disappeared over time. HLA-DR expression did not differ between 33°C and 36°C.

CONCLUSIONS

Patients after cardiac arrest have a modest systemic inflammatory response compared to healthy controls, associated with lower HLA-DR expression and attenuated immune response to Gram-negative and Gram-positive antigens, the latter indicative of an impaired immune response to bacteria. Patients with a body temperature of 33°C did not differ from patients with a body temperature of 36°C, suggesting induced hypothermia does not affect immune response in patients with cardiac arrest.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01020916, registered 25 November 2009.

Post-cardiac arrest therapeutic hypothermia in New Jersey hospitals: analysis of adoption and implementation

BACKGROUND

While national guidelines recommend the use of therapeutic hypothermia (TH) for the treatment of out-of-hospital cardiac arrest (OHCA), adoption of the technique has been slow. In addition, little is known about how TH is applied in practice. This study sought to characterize the adoption and implementation of TH by acute care hospitals in the state of New Jersey.

METHODS

A survey of all 73 acute care hospitals in New Jersey was conducted to solicit information about TH adoption, application, and methods. Additional information was gained through a review of 18 written TH protocols (covering 21 hospitals).

RESULTS

After growing slowly from 2004 to 2008, TH use among New Jersey hospitals accelerated between 2009 and 2011. By 2011, 68.4% of New Jersey hospitals had a TH program in place, with an additional 13.6% indicating plans to begin one. Most hospitals indicated low volumes of OHCA patients (e.g., ≤10 per month). There was no relationship between OHCA volume and development of a TH program. The per hospital volume of OHCA patients receiving TH is even lower given the extensive patient exclusion criteria used by many facilities. TH hospitals vary widely in their TH exclusion criteria and cooling equipment and methods.

DISCUSSION

The vast majority of New Jersey hospitals are now organized to implement national TH guidelines for initial survivors of OHCA. However, limited volumes of OHCA cases per hospital and lack of uniformity on how the guidelines are implemented raise new questions about the effectiveness of current practice in postarrest care. More detailed analysis of TH volumes versus outcomes and comparative studies of TH techniques are required to optimize postarrest care.

A 4-year implementation strategy of aggressive post-resuscitation care and temperature management after cardiac arrest

BACKGROUND

target temperature management (TTM) not only improves neurological outcome and survival but has given momentum to a more aggressive and comprehensive treatment after resuscitation. Yet, implementation issues represent the main obstacle to systematic treatment with TTM and aggressive post-resuscitation care. We devised a strategy to introduce, monitor and improve the quality of aggressive treatment after resuscitation, including TTM.

METHODS

standard operative procedures on aggressive post-resuscitation care, written jointly by physicians and nurses, were introduced in November 2004. Data of all resuscitated patients admitted to the ICU were prospectively acquired for 4 years. Periodic audits (every 16 months) were programmed, leading to three equally long periods. Several critical issues were identified after each audit and addressed subsequently, leading to a growing complexity of care. Moreover, after 2 years we introduced an educational programme with medical credits for all staff attending critically ill patients. Neurological outcome and survival at hospital discharged were compared to historical controls of the preceding 22 months.

RESULTS

129 consecutively resuscitated patients were admitted to the ICU in the 4-year study period. Of these, 96 (74%) were treated with TTM and aggressive post-resuscitation care. Favourable neurological recovery among patients discharged alive significantly improved in the 4-year intervention period (81% vs. 50% in historical controls, p<0.01). A composite endpoint of mortality and poor neurological outcome also improved (64% vs. 82% respectively, p<0.05). Overall survival increased throughout the 4 years, leading to a significant improvement in the 3rd period compared to historical controls (60% vs. 35%; p<0.05).

CONCLUSIONS

we propose a strategy to successfully introduce and implement TTM and aggressive post-resuscitation care via standard operative procedures, periodic audits and feedback. Continuous education among other factors contributed to a significant improvement in neurological outcome and a progressive increase in survival.

SOPs and the right hospitals to improve outcome after cardiac arrest

Approximately 400,000 Europeans are yearly resuscitated from out-of-hospital cardiac arrest (OHCA).(1,2) Despite evolving evidence based guidelines for cardiopulmonary resuscitation (CPR), survival rates after OHCA has not improved much in several places around the world. However, a potential for improved survival is absolutely present, based on the huge spread in worldwide survival; some cities with survival over 20-30% and some cities with just a few percent.(1,2) These survival differences can partly be explained by different definitions of OHCA,(2) but mainly due to the overall quality of the local Chain of Survival (COS)(3); early arrest recognition and call for help, early CPR, early defibrillation and early post resuscitation care. By identifying and thereafter improving weak links in the local COS, survival can indeed increase. This review will focus on the quality of the last link in the COS, the hospital treatment after return of spontaneuous circulation (ROSC), and how good quality post resuscitation care can improve not only survival, but survival with neurologically intact outcome.

Therapeutic hypothermia after in-hospital cardiac arrest: a critique

More than 210,000 in-hospital cardiac arrests occur annually in the United States. Use of moderate therapeutic hypothermia (TH) in comatose survivors after return of spontaneous circulation following out-of-hospital cardiac arrest (OOH-CA) caused by ventricular fibrillation or pulseless ventricular tachycardia is recommended strongly by many professional organizations and societies. The use of TH after cardiac arrest associated with nonshockable rhythms and after in-hospital cardiac arrest (IH-CA) is recommended to be considered by these same organizations and is being applied widely. The use in these latter circumstances is based on an extrapolation of the data supporting its use after out-of-hospital cardiac arrest associated with shockable rhythms. The purpose of this article is to review the limitations of existing data supporting these extended application of TH after cardiac arrest and to suggest approaches to this dilemma. The data supporting its use for OOH-CA appear to this author, and to some others, to be rather weak, and the data supporting the use of TH for IH-CA appear to be even weaker and to include no randomized controlled trials (RCTs) or supportive observational studies. The many reasons why TH might be expected to be less effective following IH-CA are reviewed. The degree of neurologic injury may be more severe in many of these cases and, thus, may not be responsive to TH as currently practiced following OOH-CA. The potential adverse consequences of the routine use of TH for IH-CA are listed and include complications associated with TH, interference with diagnostic and interventional therapy, and use of scarce personnel and financial resources. Most importantly, it inhibits the ability of researchers to conduct needed RCTs. The author believes that the proper method of providing TH in these cases needs to be better defined. Based on this analysis the author concludes that TH should not be used indiscriminantly following most cases of IH-CA, and instead clinicians should concentrate their efforts in conducting high-quality large RCTs or large-scale, well-designed prospective observation studies to determine its benefits and identify appropriate candidates.

Therapeutic hypothermia after cardiopulmonary resuscitation

Full cerebral recovery after cardiopulmonary resuscitation is still a rare event. Unfortunately, up to now, no specific and outcome-improving therapy was available after such events. From several cases it is known that low body and brain temperature during a cardiocirculatory arrest improves the neurological outcome following these events. As it is not possible in acute events to induce hypothermia beforehand, whether cooling after the insult could also be protective was evaluated. After animal studies in the 1990s and first clinical pilot trials of mild therapeutic and induced hypothermia, two randomized trials of hypothermic therapy after successful resuscitation after cardiac arrest were conducted. These studies demonstrated that hypothermia after cardiac arrest could improve neurological outcome as well as overall mortality.

Targeted temperature management at 33°C versus 36°C after cardiac arrest

BACKGROUND

Unconscious survivors of out-of-hospital cardiac arrest have a high risk of death or poor neurologic function. Therapeutic hypothermia is recommended by international guidelines, but the supporting evidence is limited, and the target temperature associated with the best outcome is unknown. Our objective was to compare two target temperatures, both intended to prevent fever.

METHODS

In an international trial, we randomly assigned 950 unconscious adults after out-of-hospital cardiac arrest of presumed cardiac cause to targeted temperature management at either 33°C or 36°C. The primary outcome was all-cause mortality through the end of the trial. Secondary outcomes included a composite of poor neurologic function or death at 180 days, as evaluated with the Cerebral Performance Category (CPC) scale and the modified Rankin scale.

RESULTS

In total, 939 patients were included in the primary analysis. At the end of the trial, 50% of the patients in the 33°C group (235 of 473 patients) had died, as compared with 48% of the patients in the 36°C group (225 of 466 patients) (hazard ratio with a temperature of 33°C, 1.06; 95% confidence interval [CI], 0.89 to 1.28; P=0.51). At the 180-day follow-up, 54% of the patients in the 33°C group had died or had poor neurologic function according to the CPC, as compared with 52% of patients in the 36°C group (risk ratio, 1.02; 95% CI, 0.88 to 1.16; P=0.78). In the analysis using the modified Rankin scale, the comparable rate was 52% in both groups (risk ratio, 1.01; 95% CI, 0.89 to 1.14; P=0.87). The results of analyses adjusted for known prognostic factors were similar.

CONCLUSIONS

In unconscious survivors of out-of-hospital cardiac arrest of presumed cardiac cause, hypothermia at a targeted temperature of 33°C did not confer a benefit as compared with a targeted temperature of 36°C. (Funded by the Swedish Heart-Lung Foundation and others; TTM ClinicalTrials.gov number, NCT01020916.).

Therapeutic hypothermia in Italian Intensive Care Units after 2010 resuscitation guidelines: still a lot to do

BACKGROUND

Therapeutic hypothermia (TH) is one of three interventions that have demonstrated to improve patients' neurological outcome after cardiac arrest. The aim of this study was to investigate the effect of the 2010 resuscitation guidelines on TH implementation in various Italian Intensive Care Units (ICU).

METHODS

A structured questionnaire was submitted to Italian ICU. The questionnaire was addressed to determine the procedures of TH in each ICU or, on the contrary, the reason for not employing the therapy.

RESULTS

We obtained complete information from 770 of 847 Italian ICU (91%). Out of 405 Units included in the analysis only 223 (55.1%) reported to use TH in comatose patients after return of spontaneous circulation. The trend of TH implementation shows a stable increase, particularly after 2006 but there is no evident acceleration after the strong indication of the 2010 guidelines. There was a rise of about 3.4 times in the number of Italian ICU using TH as compared to the 2007 survey (an increase of 68% per year). One hundred and eighty-two (44.9%) units did not use TH mainly because of lack of equipment, economic issues or the conviction of the difficulty of execution.

CONCLUSIONS

TH is still under-used in Italy (55.1%) even though the therapy is strongly recommended in the 2010 guidelines. However, the increase in the adoption of hypothermia has been significant in the past 5 years (68%/years) and the awareness of the efficacy is almost consolidated among intensivists, being logistic problems the leading cause for non-adoption.

Brain Injury as a Risk Factor for Fever Upon Admission to the Intensive Care Unit and Association With In-Hospital Case Fatality

Purpose:

To test the hypothesis that fever was more frequent in critically ill patients with brain injury when compared to nonneurological patients and to study its effect on in-hospital case fatality.

Methods:

Retrospective matched cohort study utilizing a single-center prospectively compiled registry. Critically ill neurological patients ≥18 years and consecutively admitted to the intensive care unit (ICU) with acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), and traumatic brain injury (TBI) were selected. Patients were matched by sex, age, and Acute Physiology and Chronic Health Evaluation II (APACHE-II) to a cohort of nonneurological patients. Fever was defined as any temperature ≥37.5°C within the first 24 hours upon admission to the ICU. The primary outcome measure was in-hospital case fatality.

Results:

Mean age among neurological patients was 65.6 ± 15 years, 46% were men, and median APACHE-II was 15 (interquartile range 11-20). There were 18% AIS, 27% ICH, and 6% TBI. More neurological patients experienced fever than nonneurological patients (59% vs 47%, P = .007). The mean hospital length of stay was higher for nonneurological patients (18 ± 20 vs 14 ± 15 days, P = .007), and more neurological patients were dead at hospital discharge (29% vs 20%, P < .0001). After risk factor adjustment, diagnosis (neurological vs nonneurological), and the probability of being exposed to fever (propensity score), the following variables were associated with higher in-hospital case fatality: APACHE-II, neurological diagnosis, mean arterial pressure, cardiovascular and respiratory dysfunction in ICU, and fever (odds ratio 1.9, 95% confidence interval 1.04-3.6, P = .04).

Conclusion:

These data suggest that fever is a frequent occurrence after brain injury, and that it is independently associated with in-hospital case fatality.

[Anesthesia-related cardiac arrest in children. Data from a tertiary referral hospital registry]

OBJECTIVES

The aim of this study is to analyze the cardiac arrests related to anesthesia in a tertiary children's hospital, in order to identify risk factors that would lead to opportunities for improvement.

METHODS

A 5-year retrospective study was conducted on anesthesia related cardiac arrest occurring in pediatric patients. All urgent and elective anesthetic procedures performed by anesthesiologists were included. Data collected included patient characteristics, the procedure, the probable cause, and outcome of the cardiac arrest. Odds ratio was calculated by univariate analysis to determine the clinical factors associated with cardiac arrest and mortality.

RESULTS

There were a total of 15 cardiac arrests related to anesthesia in 43,391 anesthetic procedures (3.4 per 10,000), with an incidence in children with ASA I-II versus ASA≥III of 0.28 and 19.27 per 10,000, respectively. The main risk factors were children ASA≥III (P<.001), less than one month old (P<.001), less than one year old (P<.001), emergency procedures (P<.01), cardiac procedures (P<.001) and procedures performed in the catheterization laboratory (P<.05). The main causes of cardiac arrest were cardiovascular (53.3%), mainly due to hypovolemia, and cardiovascular depression associated with induction of anesthesia, followed by respiratory causes (20%), and medication causes (20%). The incidence of mortality and neurological injury within the first 24h after the cardiac arrest was 0.92 and 1.38 per 10,000, respectively. The mortality in the first 3 months was 1.6 per 10,000. The main causes of death were ASA≥III, age under one year, pulmonary arterial hypertension, cardiac arrest in areas remote from the surgery area, a duration of cardiopulmonary resuscitation over 20min, and when hypothermia was not applied after cardiac arrest.

CONCLUSION

The main risk factors for cardiac arrest were ASA≥III, age under one year, emergency procedures, cardiology procedures and procedures performed in the catheterization laboratory. The main cause of the cardiac arrest was due mainly to cardiovascular hypovolemia. All patients who died or had neurological injury were ASA≥III. Pulmonary arterial hypertension is a risk of anesthesia-related mortality.

Rationale, timeline, study design, and protocol overview of the therapeutic hypothermia after pediatric cardiac arrest trials

OBJECTIVE

To describe the rationale, timeline, study design, and protocol overview of the Therapeutic Hypothermia after Pediatric Cardiac Arrest trials.

DESIGN

Multicenter randomized controlled trials.

SETTING

Pediatric intensive care and cardiac ICUs in the United States and Canada.

PATIENTS

Children from 48 hours to 18 years old, who have return of circulation after cardiac arrest, who meet trial eligibility criteria, and whose guardians provide written consent.

INTERVENTIONS

Therapeutic hypothermia or therapeutic normothermia.

MEASUREMENTS AND MAIN RESULTS

From concept inception in 2002 until trial initiation in 2009, 7 years were required to plan and operationalize the Therapeutic Hypothermia after Pediatric Cardiac Arrest trials. Two National Institute of Child Health and Human Development clinical trial planning grants (R21 and R34) supported feasibility assessment and protocol development. Two clinical research networks, Pediatric Emergency Care Applied Research Network and Collaborative Pediatric Critical Care Research Network, provided infrastructure resources. Two National Heart Lung Blood Institute U01 awards provided funding to conduct separate trials of in-hospital and out-of-hospital cardiac arrest. A pilot vanguard phase that included half the clinical sites began on March 9, 2009, and this was followed by full trial funding through 2015.

CONCLUSIONS

Over a decade will have been required to plan, design, operationalize, and conduct the Therapeutic Hypothermia after Pediatric Cardiac Arrest trials. Details described in this report, such as participation of clinical research networks and clinical trial planning grants utilization, may be of utility for individuals who are planning investigator-initiated, federally supported clinical trials.