Therapeutic hypothermia after cardiac arrest: implementation and outcome in Finnish intensive care units

Changes in Practice of Controlled Hypothermia after Cardiac Arrest in the Past 20 Years: A Critical Care Perspective

For 20 years, induced hypothermia and targeted temperature management have been recommended to mitigate brain injury and increase survival after cardiac arrest. On the basis of animal research and small clinical trials, the International Liaison Committee on Resuscitation strongly advocated hypothermia at 32-34 °C for 12-24 hours for comatose patients with out-of-hospital cardiac arrest with initial rhythm of ventricular fibrillation or nonperfusing ventricular tachycardia. The intervention was implemented worldwide. In the past decade, hypothermia and targeted temperature management have been investigated in larger clinical randomized trials focusing on target temperature depth, target temperature duration, prehospital versus in-hospital initiation, nonshockable rhythms, and in-hospital cardiac arrest. Systematic reviews suggest little or no effect of delivering the intervention on the basis of the summary of evidence, and the International Liaison Committee on Resuscitation today recommends only to treat fever and keep body temperature below 37.5 °C (weak recommendation, low-certainty evidence). Here we describe the evolution of temperature management for patients with cardiac arrest during the past 20 years and how the accrued evidence has influenced not only the recommendations but also the guideline process. We also discuss possible paths forward in this field, bringing up both whether fever management is at all beneficial for patients with cardiac arrest and which knowledge gaps future clinical trials in temperature management should address.

Blood-brain barrier disruption as a cause of various serum neuron-specific enolase cut-off values for neurological prognosis in cardiac arrest patients

We compared the cut-off and prognostic value of serum neuron-specific enolase (NSE) between groups with and without severe blood–brain barrier (BBB) disruption to reveal that a cause of various serum NSE cut-off value for neurological prognosis is severe BBB disruption in out-of-hospital cardiac arrest (OHCA) patients underwent target temperature management (TTM). This was a prospective, single-centre study conducted from January 2019 to June 2021. Severe BBB disruption was indicated using cerebrospinal fluid-serum albumin quotient values > 0.02. The area under the receiver operating characteristic curve of serum NSE obtained on day 3 of hospitalisation to predict poor outcomes was used. In patients with poor neurologic outcomes, serum NSE in those with severe BBB disruption was higher than in those without (P = 0.006). A serum NSE cut-off value of 40.4 μg/L for poor outcomes in patients without severe BBB disruption had a sensitivity of 41.7% and a specificity of 96.0%, whereas a cut-off value of 34.6 μg/L in those with severe BBB disruption had a sensitivity of 86.4% and a specificity of 100.0%. We demonstrated that the cut-off and prognostic value of serum NSE were heterogeneous, depending on severe BBB disruption in OHCA patients treated with TTM.

Usefulness of Therapeutic Hypothermia to Improve Survival in Out-of-Hospital Cardiac Arrest

Background

In recent years, therapeutic hypothermia (TH) has been used to improve outcomes in patients with out-of-hospital cardiac arrest (OHCA). Despite these recommendations, many centers are still hesitant to implement such hypothermia protocols. In this study, we assessed the effects of TH for OHCA patients.

Methods

A total of 58 OHCA patients who had return of spontaneous circulation after OHCA presumed to be due to cardiac causes were enrolled. Twenty-three patients underwent TH, which was performed using a large volume of ice crystalloid fluid infusions in the emergency room and conventional cooling blankets in the ICU to maintain a body temperature of 32-34 °C for 24 hours using a tympanic thermometer. Patients in the control group received standard supportive care without TH. Hospital survival and neurologic outcomes were compared.

Results

There were no significant differences between the groups in patient characteristics, underlying etiologies and disease severity. In the 23 patients who received TH, 17 were alive at hospital discharge. In the 35 patients who received supportive care, only 11 were alive at hospital discharge (73.91% vs. 31.43%, p = 0.0015). Approximately 52% of the patients in the TH group had good neurologic outcomes (12 of 23) compared with the 20% (7 of 35) of the patients in the supportive group (p = 0.01).

Conclusions

TH can improve the outcomes of OHCA patients. Further large-scale studies are needed to verify our results.

Neuron-Specific Enolase Predicts Poor Outcome After Cardiac Arrest and Targeted Temperature Management: A Multicenter Study on 1,053 Patients

OBJECTIVE

Outcome prediction after cardiac arrest is important to decide on continuation or withdrawal of intensive care. Neuron-specific enolase is an easily available, observer-independent prognostic biomarker. Recent studies have yielded conflicting results on its prognostic value after targeted temperature management.

DESIGN, SETTING, AND PATIENTS

We analyzed neuron-specific enolase serum concentrations 3 days after nontraumatic in-hospital cardiac arrest and out-of-hospital cardiac arrest and outcome of patients from five hospitals in Germany, Austria, and Italy. Patients were treated at 33°C for 24 hours. Cerebral Performance Category was evaluated upon ICU discharge. We performed case reviews of good outcome patients with neuron-specific enolase greater than 90 μg/L and poor outcome patients with neuron-specific enolase less than or equal to 17 μg/L (upper limit of normal).

MEASUREMENTS AND MAIN RESULTS

A neuron-specific enolase serum concentration greater than 90 μg/L predicted Cerebral Performance Category 4-5 with a positive predictive value of 99%, false positive rate of 0.5%, and a sensitivity of 48%. All three patients with neuron-specific enolase greater than 90 μg/L and Cerebral Performance Category 1-2 had confounders for neuron-specific enolase elevation. An neuron-specific enolase serum concentration less than or equal to 17 μg/L excluded Cerebral Performance Category 4-5 with a negative predictive value of 92%. The majority of 14 patients with neuron-specific enolase less than or equal to 17 μg/L who died had a cause of death other than hypoxic-ischemic encephalopathy. Specificity and sensitivity for prediction of poor outcome were independent of age, sex, and initial rhythm but higher for out-of-hospital cardiac arrest than for in-hospital cardiac arrest patients.

CONCLUSION

High neuron-specific enolase serum concentrations reliably predicted poor outcome at ICU discharge. Prediction accuracy differed and was better for out-of-hospital cardiac arrest than for in-hospital cardiac arrest patients. Our "in-the-field" data indicate 90 μg/L as a threshold associated with almost no false positives at acceptable sensitivity. Confounders of neuron-specific enolase elevation should be actively considered: neuron-specific enolase-producing tumors, acute brain diseases, and hemolysis. We strongly recommend routine hemolysis quantification. Neuron-specific enolase serum concentrations less than or equal to 17 μg/L argue against hypoxic-ischemic encephalopathy incompatible with reawakening.

Prognostic factors associated with hospital survival in comatose survivors of cardiac arrest

AIM: To identify patient, cardiac arrest and management factors associated with hospital survival in comatose survivors of cardiac arrest.

METHODS: A retrospective, single centre study of comatose patients admitted to our intensive care unit (ICU) following cardiac arrest during the twenty year period between 1993 and 2012. This study was deemed by the Human Research Ethics Committee (HREC) of Monash Health to be a quality assurance exercise, and thus did not require submission to the Monash Health HREC (Research Project Application, No. 13290Q). The study population included all patients admitted to our ICU between 1993 and 2012, with a discharge diagnosis including “cardiac arrest”. Patients were excluded if they did not have a cardiac arrest prior to ICU admission (i.e., if their primary arrest was during their admission to ICU), or were not comatose on arrival to ICU. Our primary outcome measure was survival to hospital discharge. Secondary outcome measures were ICU and hospital length of stay (LOS), and factors associated with survival to hospital discharge.

RESULTS: Five hundred and eighty-two comatose patients were admitted to our ICU following cardiac arrest, with 35% surviving to hospital discharge. The median ICU and hospital LOS was 3 and 5 d respectively. There was no survival difference between in-hospital and out-of-hospital cardiac arrests. Males made up 62% of our cardiac arrest population, were more likely to have a shockable rhythm (56% vs 37%, P < 0.001), and were more likely to survive to hospital discharge (40% vs 28%, P = 0.006). On univariate analysis, therapeutic hypothermia, regardless of method used (e.g., rapid infusion of ice cold fluids, topical ice, “Arctic Sun”, passive rewarming, “Bair Hugger”) and location initiated (e.g., pre-hospital, emergency department, intensive care) was associated with increased survival. There was however no difference in survival associated with target temperature, time at target temperature, location of initial cooling, method of initiating cooling, method of maintaining cooling or method of rewarming. Patients that survived were more likely to have a shockable rhythm (P < 0.001), shorter time to return of spontaneous circulation (P < 0.001), receive therapeutic hypothermia (P = 0.03), be of male gender (P = 0.006) and have a lower APACHE II score (P < 0.001). After multivariate analysis, only a shockable initial rhythm (OR = 6.4, 95%CI: 3.95-10.4; P < 0.01) and a shorter time to return of spontaneous circulation (OR = 0.95, 95%CI: 0.93-0.97; P < 0.01) was found to be independently associated with survival to hospital discharge.

CONCLUSION: In comatose survivors of cardiac arrest, shockable rhythm and shorter time to return of spontaneous circulation were independently associated with increased survival to hospital discharge.

Therapeutic hypothermia following cardiac arrest

More than 10 years ago, the randomised studies of therapeutic hypothermia after cardiac arrest showed significant improvement of neurological outcome and survival. Since then, it has become clear that most of the possible adverse events of therapeutic hypothermia are mild and can easily be controlled by proper administration of intensive care. Although implementation of this effective therapy is quite successful, many questions of the exact treatment protocol still remain unanswered. Therapeutic hypothermia treatment therefore must be tailored to the specific patient's needs. Hence, the exact level of target temperature, duration of cooling, rewarming, timing of the therapy and concomitant medication to facilitate therapeutic hypothermia will be important in the future. Additionally, the use of a post-resuscitation treatment bundle (specialised cardiac-arrest centres including intensive post-resuscitation care, appropriate haemodynamic and respiratory management, therapeutic hypothermia and percutaneous coronary intervention) could further improve treatment of cardiac arrest.

Neurologic outcome in comatose patients resuscitated from out-of-hospital cardiac arrest with prolonged downtime and treated with therapeutic hypothermia

BACKGROUND

Previous reports have shown that prolonged duration of resuscitation efforts in out-of-hospital cardiac arrest (OHCA) is associated with poor neurologic outcome. This concept has recently been questioned with advancements in post-cardiac arrest care including the use of therapeutic hypothermia (TH). The aim of this study was to determine the rate of good neurologic outcome based on the duration of resuscitation efforts in OHCA patients treated with TH.

METHODS

This prospective, observational, study was conducted between January 2008 and September 2012. Inclusion criteria consisted of adult non-traumatic OHCA patients who were comatose after return of spontaneous circulation (ROSC) and received TH. The primary endpoint was good neurologic outcome defined as a cerebral performance category score of 1 or 2. Downtime was calculated as the length of time between the patient being recognized as pulseless and ROSC.

RESULTS

105 patients were treated with TH and 19 were excluded due to unknown downtime, leaving 86 patients for analysis. The median downtime was 18.5 (10.0-32.3)min and 33 patients (38.0%) had a good neurologic outcome. When downtime was divided into four groups (≤10min, 11-20min, 21-30min, >30min), good neurologic outcomes were 62.5%, 37%, 25%, and 21.7%, respectively (p=0.02). However, even with downtime >20min, 22.9% had a good neurologic outcome, and this percentage increased to 37.5% in patients with an initial shockable rhythm.

CONCLUSIONS

Although longer downtime is associated with worse outcome in OHCA patients, we found that comatose patients who have been successfully resuscitated and treated with TH have neurologically intact survival rates of 23% even with downtime >20min.

Geriatric experience following cardiac arrest at six interventional cardiology centers in the United States 2006-2011: interplay of age, do-not-resuscitate order, and outcomes

OBJECTIVES

It is not known if aggressive postresuscitation care, including therapeutic hypothermia and percutaneous coronary intervention, benefits cardiac arrest survivors more than 75 years old. We compared treatments and outcomes of patients at six regional percutaneous coronary intervention centers in the United States to determine if aggressive care of elderly patients was warranted.

DESIGN

Retrospective evaluation of registry data.

SETTING

Six interventional cardiology centers in the United States.

PATIENTS

Six hundred and twenty-five unresponsive cardiac arrest survivors aged 18-75 were compared with 129 similar patients aged more than 75.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cardiac arrest survivors aged more than 75 had more comorbidities (3.0 ± 1.6 vs 2.0 ± 1.6, p < 0.001), but were matched to younger patients in initial heart rhythm, witnessed arrests, bystander cardiopulmonary resuscitation, and total ischemic time. Patients aged more than 75 frequently underwent therapeutic hypothermia (97.7%), urgent coronary angiography (44.2%), and urgent percutaneous coronary intervention (24%). They had more sustained hyperglycemia (70.5% vs 59%, p = 0.015), less postcooling fever (25.2% vs 35.2%, p = 0.03), were more likely to have do-not-resuscitate orders (65.9% vs 48.2%, p < 0.001), and undergo withdrawal of life support (61.2% vs 47.5%, p = 0.005). Good functional outcome at 6 months (Cerebral Performance Category 1-2) was seen in 27.9% elderly versus 40.4% younger patients overall (p = 0.01) and in 44% versus 55% (p = 0.13) of patients with an initial shockable rhythm. Of 35 survivors more than 75 years old, 33 (94.8%) were classified as Cerebral Performance Category 1 or 2 at (mean) 6.5-month follow-up. In multivariable logistic regression modeling, age more than 75 was significantly associated with outcome only when the presence of a do-not-resuscitate order was excluded from the model.

CONCLUSIONS

Elderly patients were more likely to have do-not-resuscitate orders and to undergo withdrawal of life support. Age was independently associated with outcome only when correction for do-not-resuscitate status was excluded, and functional outcomes of elderly survivors were similar to younger patients. Exclusion of patients more than 75 years old from aggressive care is not warranted on the basis of age alone.

Therapeutic hypothermia after out-of-hospital cardiac arrest in Finnish intensive care units: the FINNRESUSCI study

PURPOSE

We aimed to evaluate post-resuscitation care, implementation of therapeutic hypothermia (TH) and outcomes of intensive care unit (ICU)-treated out-of-hospital cardiac arrest (OHCA) patients in Finland.

METHODS

We included all adult OHCA patients admitted to 21 ICUs in Finland from March 1, 2010 to February 28, 2011 in this prospective observational study. Patients were followed (mortality and neurological outcome evaluated by Cerebral Performance Categories, CPC) within 1 year after cardiac arrest.

RESULTS

This study included 548 patients treated after OHCA. Of those, 311 patients (56.8%) had a shockable initial rhythm (incidence of 7.4/100,000/year) and 237 patients (43.2%) had a non-shockable rhythm (incidence of 5.6/100,000/year). At ICU admission, 504 (92%) patients were unconscious. TH was given to 241/281 (85.8%) unconscious patients resuscitated from shockable rhythms, with unfavourable 1-year neurological outcome (CPC 3-4-5) in 42.0% with TH versus 77.5% without TH (p < 0.001). TH was given to 70/223 (31.4%) unconscious patients resuscitated from non-shockable rhythms, with 1-year CPC of 3-4-5 in 80.6% (54/70) with TH versus 84.0% (126/153) without TH (p = 0.56). This lack of difference remained after adjustment for propensity to receive TH in patients with non-shockable rhythms.

CONCLUSIONS

One-year unfavourable neurological outcome of patients with shockable rhythms after TH was lower than in previous randomized controlled trials. However, our results do not support use of TH in patients with non-shockable rhythms.

The effect of hypothermia "dose" on vasopressor requirements and outcome after cardiac arrest

OBJECTIVES

We evaluated the association between TH use and "dose" and cumulative vasopressor and inotrope requirement, survival, and neurologic outcome.

BACKGROUND

Therapeutic hypothermia (TH) improves outcome after cardiac arrest, but may increase vasopressor and inotrope requirements.

METHODS

Chart review of in- and out-of-hospital cardiac arrests between 1/1/2005 and 3/15/2010. Data included demographic information, category of post-cardiac arrest illness severity ((I) awake, (II) coma (not following commands but intact brainstem responses)+mild cardiopulmonary dysfunction (SOFA [Sequential Organ Failure Assessment] cardiac+respiratory score<4), (III) coma+moderate-severe cardiopulmonary dysfunction (SOFA cardiac+respiratory score≥4), and (IV) coma without brainstem reflexes), cumulative vasopressor index (CVI), inotrope use, survival, and neurologic outcome. The "dose" of TH (hours*temperature below threshold) was calculated using thresholds of ≤34 °C and ≤35 °C. Data were analyzed using descriptive statistics, Student's t-test, Wilcoxon test, and chi-squared analysis. Linear and logistic regression evaluated the effect of hypothermia "dose" on total CVI, survival and neurologic outcome.

RESULTS

Among 361 comatose patients, 233 (65%) received TH. Vasopressor administration (measured by CVI) was higher in normothermic subjects (60.2% vs. 46.4%; p=0.016). Using a 34 °C threshold, SOFA respiratory subscore and PEA arrest predicted total CVI. Using a 35 °C threshold, severity of coma, SOFA respiratory subscore, PEA arrest and use of inotropic agents in addition to vasopressors predicted total CVI. Initial motor examination predicted survival and neurologic outcome, while TH "dose" did not.

CONCLUSIONS

TH delivery is not associated with vasopressor requirement. TH "dose" is not associated with total CVI, survival, or good outcome. Vasopressor or inotropic requirement should not contraindicate TH use.

Regional variation and outcome of out-of-hospital cardiac arrest (ohca) in Finland - the Finnresusci study

Background

Despite the efforts of the modern Emergency Medical Service Systems (EMS), survival rates for sudden out-of-hospital cardiac arrest (OHCA) have been poor as approximately 10% of OHCA patients survive hospital discharge. Many aspects of OHCA have been studied, but few previous reports on OHCA have documented the variation between different sizes of study areas on a regional scale. The aim of this study was to report the incidence, outcomes and regional variation of OHCA in the Finnish population.

Methods

From March 1st to August 31st, 2010, data on all OHCA patients in the southern, central and eastern parts of Finland was collected. Data collection was initiated via dispatch centres whenever there was a suspected OHCA case or if a patient developed OHCA before arriving at the hospital. The study area includes 49% of the Finnish population; they are served by eight dispatch centres, two university hospitals and six central hospitals.

Results

The study period included 1042 cases of OHCA. Resuscitation was attempted on 671 patients (64.4%), an incidence of 51/100,000 inhabitants/year. The initial rhythm was shockable for 211 patients (31.4%). The survival rate at one-year post-OHCA was 13.4%. Of the witnessed OHCA events with a shockable rhythm of presumed cardiac origin (n=140), 64 patients (45.7%) were alive at hospital discharge and 47 (33.6%) were still living one year hence. Surviving until hospital admission was more likely if the OHCA occurred in an urban municipality (41.5%, p=0.001).

Conclusions

The results of this comprehensive regional study of OHCA in Finland seem comparable to those previously reported in other countries. The survival of witnessed OHCA events with shockable initial rhythms has improved in urban Finland in recent decades.

[Therapeutic hypothermia and management of sudden death]

Due to its protective effects on the brain and potentially the myocardium, cooling therapy is clearly part of the standard of care of any sudden death especially in the setting of myocardial infarction. Recent guidelines recommend cooling therapy (32 to 34 °C) for 12 to 24 hours in unconscious patients with spontaneous circulation after resuscitated sudden death. We provide here a review of clinical evidence, cooling techniques and potential adverse effects of cooling therapy.

Mortality in out-of-hospital cardiac arrest patients has decreased in the era of therapeutic hypothermia

BACKGROUND

Mild therapeutic hypothermia (TH) improves survival after out-of-hospital cardiac arrest (OHCA). This treatment was implemented in most Finnish intensive care units (ICUs) in 2003. The aim of this study was to find out whether hospital mortality of ICU-treated OHCA patients has changed in the era of TH.

METHODS

This was a retrospective study of data collected prospectively into the database of the Finnish Intensive Care Consortium during the years 2000-2008. The study population consisted of 3958 patients for whom cardiac arrest was registered as the reason for ICU admission and who were transferred to the ICU from the emergency department. We divided the patients into those treated in the pre-hypothermia era (2000-2002) and those treated in the hypothermia era (2003-2008). We investigated whether the treatment period had any impact on hospital mortality.

RESULTS

There were no differences between the periods regarding the age or initial Glasgow Coma Scores of the patients. Mean severity of illness was higher in the latter period. Despite this, mortality decreased: the hospital mortality rate was 57.9% in 2000-2002 and 51.1% in 2003-2008, P < 0.001. In a multivariate logistic regression analysis, treatment in 2003-2008 was associated with a reduced risk of in-hospital death (adjusted odds ratio 0.54, 95% confidence interval 0.45-0.64 and P < 0.001). Survival improved markedly between the years 2002 and 2003. This improvement has persisted, but there has been no further improvement.

CONCLUSION

Concurrently with the implementation of TH, hospital mortality of OHCA patients treated in Finnish ICUs decreased.

Relationship between time to target temperature and outcome in patients treated with therapeutic hypothermia after cardiac arrest

INTRODUCTION

Our purpose was to study whether the time to target temperature correlates with neurologic outcome in patients after cardiac arrest with restoration of spontaneous circulation treated with therapeutic mild hypothermia in an academic emergency department.

METHODS

Temperature data between April 1995 and June 2008 were collected from 588 patients and analyzed in a retrospective cohort study by observers blinded to outcome. The time needed to achieve an esophageal temperature of less than 34°C was recorded. Survival and neurological outcomes were determined within six months after cardiac arrest.

RESULTS

The median time from restoration of spontaneous circulation to reaching a temperature of less than 34°C was 209 minutes (interquartile range [IQR]: 130-302) in patients with favorable neurological outcomes compared to 158 min (IQR: 101-230) (P < 0.01) in patients with unfavorable neurological outcomes. The adjusted odds ratio for a favorable neurological outcome with a longer time to target temperature was 1.86 (95% CI 1.03 to 3.38, P = 0.04).

CONCLUSIONS

In comatose cardiac arrest patients treated with therapeutic hypothermia after return of spontaneous circulation, a faster decline in body temperature to the 34°C target appears to predict an unfavorable neurologic outcome.

The role of hypothermia in post-cardiac arrest patients with return of spontaneous circulation: a systematic review

OBJECTIVES

To update a comprehensive systematic review of the use of therapeutic hypothermia after cardiac arrest that was undertaken initially as part of the 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. The specific question addressed was: 'in post-cardiac arrest patients with a return of spontaneous circulation, does the induction of mild hypothermia improve morbidity or mortality when compared with usual care?'

METHODS

Pubmed was searched using ("heart arrest" or "cardiopulmonary resuscitation") AND "hypothermia, induced" using 'Clinical Queries' search strategy; EmBASE was searched using (heart arrest) OR (cardiopulmonary resuscitation) AND hypothermia; The Cochrane database of systematic reviews; ECC EndNote Library for "hypothermia" in abstract OR title. Excluded were animal studies, reviews and editorials, surveys of implementation, analytical models, reports of single cases, pre-arrest or during arrest cooling and group where the intervention was not hypothermia alone.

RESULTS

77 studies met the criteria for further review. Of these, four were meta-analyses (LOE 1); seven were randomised controlled trials (LOE 1), although six of these were from the same set of patients; nine were non-randomised, concurrent controls (LOE 2); 15 were trials with retrospective controls (LOE 3); 40 had no controls (LOE 4); and one was extrapolated from a non-cardiac arrest group (LOE 5).

CONCLUSION

There is evidence supporting the use of mild therapeutic hypothermia to improve neurological outcome in patients who remain comatose following the return of spontaneous circulation after a cardiac arrest; however, much of the evidence is from low-level, observational studies. Of seven randomised controlled trials, six use data from the same patients.

Therapeutic hypothermia is associated with a decrease in urine output in acute stroke patients

AIMS

It is unclear what effect therapeutic hypothermia may have on renal function, because its effect has so far been primarily evaluated in settings in which there may be possible confounding perturbations in cardiovascular and renal physiology, such deep intraoperative hypothermia, general anesthesia, and post-cardiac arrest. We sought to determine if therapeutic hypothermia affects renal function in awake patients with normal renal function who were enrolled into a clinical trial of hypothermia plus intravenous thrombolysis for acute ischemic stroke.

METHODS

Eleven patients with normal renal function were cooled to 33°C for 24 h using an endovascular catheter, and then re-warmed over 12 h to 36.5°C, while hourly temperature, blood pressure, and fluid status data was recorded. Blood samples for blood urea nitrogen (BUN), creatinine, and hematocrit were drawn prior to treatment (baseline), immediately after hypothermia and re-warming (day 2), and again at day 7 or discharge, and values compared.

RESULTS

On initiation of cooling, temperatures dropped from a median pre-treatment value of 36.1°C (IQR: 35.8-36.4°C) to 33.1°C (IQR: 33.1-33.4°C). Urine output decreased 5.1 ml/h for every 1°C decrease in body temperature (p-value=0.001), with no associated serious adverse events. There were no statistically significant changes in BUN, creatinine, or hematocrit in the hypothermia patients.

CONCLUSION

Inducing hypothermia in patients with relatively unperturbed renal physiology results in a decrease in urine output that is linearly correlated with the decrease in core temperature. This has important implications for fluid management in patients undergoing therapeutic hypothermia.

Hypothermia after cardiac arrest should be further evaluated--a systematic review of randomised trials with meta-analysis and trial sequential analysis

BACKGROUND

Guidelines recommend mild induced hypothermia (MIH) to reduce mortality and neurological impairment after out-of-hospital cardiac arrest. Our objective was to systematically evaluate the evidence for MIH taking into consideration the risks of systematic and random error and to GRADE the evidence.

METHODS

Systematic review with meta-analysis and trial sequential analysis of randomised trials evaluating MIH after cardiac arrest in adults. We searched CENTRAL, MEDLINE, and EMBASE databases until May 2009. Retrieved trials were evaluated with Cochrane methodology. Meta-analytic estimates were calculated with random- and fixed-effects models and random errors were evaluated with trial sequential analysis (TSA).

RESULTS

Five randomised trials (478 patients) were included. All trials had substantial risk of bias. The relative risk (RR) for death was 0.84 (95% confidence interval (CI) 0.70 to 1.01) and for poor neurological outcome 0.78 (95% CI 0.64 to 0.95). For the two trials with least risk of bias the RR for death was 0.92 (95% CI 0.56 to 1.51) and for poor neurological outcome 0.92 (95% confidence interval 0.56 to 1.50). TSA indicated lack of firm evidence for a beneficial effect. The substantial risk of bias and concerns with directness rated down the quality of the evidence to low.

CONCLUSIONS

Evidence regarding MIH after out-of-hospital cardiac arrest is still inconclusive and associated with non-negligible risks of systematic and random errors. Using GRADE-methodology, we conclude that the quality of evidence is low. Our findings demonstrate that clinical equipoise exists and that large well-designed randomised trials with low risk of bias are needed.

Therapeutic hypothermia after cardiac arrest - implementation in UK intensive care units

A telephone survey was carried out to determine how many United Kingdom intensive care units were using therapeutic hypothermia as part of their management of unconscious patients admitted after cardiac arrest. All 247 intensive care units listed in the 2008 Directory of Critical Care Services were contacted to determine how many units were using hypothermia as part of their post-cardiac arrest management and how it was implemented. We obtained information from 243 (98.4%) of the intensive care units. At the time of the study, 208 (85.6%) were using hypothermia as part of post-cardiac arrest management. There has been a steady increase annually in the number of units performing therapeutic cooling from 2003 to date, with the majority of units starting in 2007 or 2008. The International Liaison Committee on Resuscitation guidelines, which recommend the use of therapeutic hypothermia for comatose patients following successful resuscitation from cardiac arrest, have taken at least 4-5 years to achieve widespread implementation in the United Kingdom.

Active surface cooling protocol to induce mild therapeutic hypothermia after out-of-hospital cardiac arrest: a retrospective before-and-after comparison in a single hospital

OBJECTIVE

To evaluate whether implementation of a therapeutic hypothermia protocol on arrival in a community hospital improved survival and neurologic outcomes in patients initially found to have ventricular fibrillation, pulseless electrical activity, or asystole, and then successfully resuscitated from out-of-hospital cardiac arrest.

DESIGN

A retrospective study of patients who presented after implementation of a therapeutic hypothermia protocol compared with those who presented before the protocol was implemented.

SETTING

Harborview Medical Center, Seattle, WA.

PATIENTS

A total of 491 consecutive adults with out-of-hospital, nontraumatic cardiac arrest who presented between January 1, 2000 and December 31, 2004.

INTERVENTIONS

An active cooling therapeutic hypothermia protocol, using ice packs, cooling blankets, or cooling pads to achieve a temperature of 32 degrees C to 34 degrees C was initiated on November 18, 2002 for unconscious patients resuscitated from cardiac arrest.

MEASUREMENTS AND MAIN RESULTS

Demographics and outcomes were obtained from medical records and an emergency medical database. The primary outcomes were survival and favorable neurologic outcome at discharge associated with the therapeutic hypothermia protocol. An adjusted analysis was performed, using a multivariate regression. During the therapeutic hypothermia period, 204 patients were brought to the emergency department; of these 204 patients, 132 (65%) ultimately achieved temperatures of <34 degrees C. Of the 72 patients who did not achieve goal temperatures: 40 (20%) died in the emergency department or shortly after being admitted to the hospital, 15 (7%) regained consciousness, four (2%) had contraindications, 13 (6%) had temperature increase or did not have documented use of the therapeutic hypothermia protocol. In the prior period, none of the 287 patients received active cooling. Patients admitted in the therapeutic hypothermia period had a mean esophageal temperature of 34.1 degrees C during the first 12 hrs compared with 35.2 degrees C in the pretherapeutic hypothermia period (p < .01). Survival to hospital discharge improved in the therapeutic hypothermia period in patients with an initial rhythm of ventricular fibrillation (odds ratio, 1.88, 95% confidence interval, 1.03-3.45), however not in patients with nonventricular fibrillation (odds ratio, 1.17, 95% confidence interval, 0.66-2.05). In adjusted analysis, ventricular fibrillation patients during the therapeutic hypothermia period trended toward improved survival (odds ratio, 1.71, 95% confidence interval, 0.85-3.46) and had favorable neurologic outcome (odds ratio, 2.62, 95% confidence interval, 1.1-6.27) compared with the earlier period. This benefit was not observed in patients whose initial rhythm was pulseless electrical activity or asystole.

CONCLUSIONS

The therapeutic hypothermia period was associated with a significant improvement in neurologic outcomes in patients whose initial rhythm was ventricular fibrillation, but not in patients with other rhythms.

Prognostic factors and outcome after drowning in an adult population

BACKGROUND

Drowning remains an actual problem. Although medical assistance has improved, it still has high rates of morbidity and mortality. We set out to explore the clinical characteristics and outcome of drowning patients admitted to the intensive care unit (ICU) of tertiary-care university hospital.

METHODS

We designed a retrospective observational study to analyse all drowning patients admitted to our ICU after successful cardiopulmonary resuscitation. The study was conducted during 1 January 1992-31 December 2005. There was no exclusion. We used a univariate analysis to evaluate the effect on patient and management characteristics on survival.

RESULTS

There were 43 patients (five children and 38 adults), with male predominance. Fifteen patients, all adults (34.9%), died. Submersion time, age, Glasgow Coma Score (GCS), pupillary reactivity and acute physiology and chronic health evaluation (APACHE II) at ICU admission were related to mortality. Non-survivors presented a higher glycaemia level at ICU admission than survivors (P=0.005).

CONCLUSIONS

The outcome is closely related to the patient's clinical status on arrival to the hospital. We have found that submersion time, age, GCS, pupillary reactivity and APACHE II at ICU admission were related to mortality. Further research in prospective studies is needed.

Outcome, timing and adverse events in therapeutic hypothermia after out-of-hospital cardiac arrest

BACKGROUND

Therapeutic hypothermia (TH) after cardiac arrest protects from neurological sequels and death and is recommended in guidelines. The Hypothermia Registry was founded to the monitor outcome, performance and complications of TH.

METHODS

Data on out-of-hospital cardiac arrest (OHCA) patients admitted to intensive care for TH were registered. Hospital survival and long-term outcome (6-12 months) were documented using the Cerebral Performance Category (CPC) scale, CPC 1-2 representing a good outcome and 3-5 a bad outcome.

RESULTS

From October 2004 to October 2008, 986 TH-treated OHCA patients of all causes were included in the registry. Long-term outcome was reported in 975 patients. The median time from arrest to initiation of TH was 90 min (interquartile range, 60-165 min) and time to achieving the target temperature (< or =34 degrees C) was 260 min (178-400 min). Half of the patients underwent coronary angiography and one-third underwent percutaneous coronary intervention (PCI). Higher age, longer time to return of spontaneous circulation, lower Glasgow Coma Scale at admission, unwitnessed arrest and initial rhythm asystole were all predictors of bad outcome, whereas time to initiation of TH and time to reach the goal temperature had no significant association. Bleeding requiring transfusion occurred in 4% of patients, with a significantly higher risk if angiography/PCI was performed (2.8% vs. 6.2%P=0.02).

CONCLUSIONS

Half of the patients survived, with >90% having a good neurological function at long-term follow-up. Factors related to the timing of TH had no apparent association to outcome. The incidence of adverse events was acceptable but the risk of bleeding was increased if angiography/PCI was performed.

Prehospital therapeutic hypothermia for comatose survivors of cardiac arrest: a randomized controlled trial

BACKGROUND

Intravenous infusion of ice-cold fluid is considered a feasible method to induce mild therapeutic hypothermia in cardiac arrest survivors. However, only one randomized controlled trial evaluating this treatment exists. Furthermore, the implementation rate of prehospital cooling is low. The aim of this study was to evaluate the efficacy and safety of this method in comparison with conventional therapy with spontaneous cooling often observed in prehospital patients.

METHODS

A randomized controlled trial was conducted in a physician-staffed helicopter emergency medical service. After successful initial resuscitation, patients were randomized to receive either +4 degrees C Ringer's solution with a target temperature of 33 degrees C or conventional fluid therapy. As an endpoint, nasopharyngeal temperature was recorded at the time of hospital admission.

RESULTS

Out of 44 screened patients, 19 were analysed in the treatment group and 18 in the control group. The two groups were comparable in terms of baseline characteristics. The core temperature was markedly lower in the hypothermia group at the time of hospital admission (34.1+/-0.9 degrees C vs. 35.2+/-0.8 degrees C, P<0.001) after a comparable duration of transportation. Otherwise, there were no significant differences between the groups regarding safety or secondary outcome measures such as neurological outcome and mortality.

CONCLUSION

Spontaneous cooling alone is insufficient to induce therapeutic hypothermia before hospital admission. Infusion of ice-cold fluid after return of spontaneous circulation was found to be well tolerated and effective. This method of cooling should be considered as an important first link in the 'cold chain' of prehospital comatose cardiac arrest survivors.

Intracerebral monitoring in comatose patients treated with hypothermia after a cardiac arrest

BACKGROUND

Induced mild hypothermia (32-34 degrees C) has proven to reduce ischemic brain injury and improve outcome after a cardiac arrest (CA). The aim of this investigation was to study the occurrence of increased intracranial pressure (ICP) and neurochemical metabolic changes indicating cerebral ischemia, after CA and cardiopulmonary resuscitation (CPR), when induced hypothermia was applied.

METHODS

ICP, brain chemistry and brain temperature were monitored during induced hypothermia and re-warming in four adult unconscious patients with restoration of spontaneous circulation after CA and CPR.

RESULTS

ICP was occasionally above 20 mmHg. Neurochemical changes indicating cerebral ischemia (increased lactate/pyruvate ratio) and excitoxicity (increased glutamate) were found after CA, and signs of ischemia were also observed during the re-warming phase. A biphasic increase in glycerol was seen, which may have been a result of both membrane degradation and overspill from the general circulation.

CONCLUSIONS

Intracerebral microdialysis and ICP monitoring may be used in selected patients not requiring anticoagulants and PCI to obtain information regarding the common disturbances of intracranial dynamics after CA. The results of this study underline the importance of inducing hypothermia quickly after CA and emphasize the need for developing tools for guidance of the re-warming.

Outcomes of a hospital-wide plan to improve care of comatose survivors of cardiac arrest

BACKGROUND

Therapeutic hypothermia (TH) improves outcomes in comatose survivors of cardiac arrest. Few hospitals have protocol-driven plans that include TH. We implemented a series of process interventions designed to increase TH use and improve outcomes in patients successfully resuscitated from out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA).

METHODS AND RESULTS

Linked interventions including a TH order sheet, verbal and written feedback to individual providers, an educational program, TH "kit" and on-call consultants to assist with patient care and hypothermia induction were implemented between January 1, 2005 and December 31, 2007 in a large, university-affiliated, tertiary care center. We then completed a retrospective review of all patients treated for cardiac arrest during the study period. Descriptive statistics, chi-squared analyses, or Fisher's exact test were used as appropriate. A p value <0.05 was considered significant. 135 OHCA patients and 106 IHCA patients were eligible for post-arrest care. TH use increased each year in the OHCA group (from 6% to 65% to 76%; p<0.001) and IHCA group (from 0% to 36% to 53%; p=.02). A good outcome was achieved in 21% and 8% of comatose patients with OHCA and IHCA, respectively. Patients with OHCA and ventricular dysrhythmia were more likely to have a good outcome with TH treatment than without it (good outcome in 57% vs. 8%; p=.005).

CONCLUSION

Implementing a series of aggressive interventions increased appropriate TH use and was associated with improved outcomes in our facility.

Can outcome prediction data change patient outcomes and organizational outcomes?

PURPOSE OF REVIEW

Intensive care medicine consumes a high share of healthcare costs, and there is growing pressure to use the scarce resources efficiently. Accordingly, organizational issues and quality management have become an important focus of interest in recent years. Here, we will review current concepts of how outcome data can be used to identify areas requiring action.

RECENT FINDINGS

Using recently established models of outcome assessment, wide variability between individual ICUs is found, both with respect to outcome and resource use. Such variability implies that there are large differences in patient care processes not only within the ICU but also in pre-ICU and post-ICU care. Indeed, measures to improve the patient process in the ICU (including care of the critically ill, patient safety, and management of the ICU) have been presented in a number of recently published papers.

SUMMARY

Outcome assessment models provide an important framework for benchmarking. They may help the individual ICU to spot appropriate fields of action, plan and initiate quality improvement projects, and monitor the consequences of such activity.

Postresuscitation care

Cardiac arrest in infants and children is a rare but critical event that typically follows a period of respiratory or circulatory compromise and has a low survival rate. The only intervention demonstrated to increase survival rate is the provision of bystander CPR. This article examines the pathophysiology of the postarrest reperfusion state; postresuscitation care of the respiratory and cardiovascular systems; postresuscitation neurologic management; therapeutic hypothermia; blood glucose control; immunologic disturbances and infections; coagulation abnormalities; and gastrointestinal and hepatic dysfunction, among other topics.

Use of induced hypothermia for neuroprotection: indications and application

Therapeutic temperature regulation has become an exciting field of interest. Mild-to-moderate hypothermia is a safe and feasible management strategy for neuroprotection and control of intracranial pressure in neurological catastrophies such as traumatic brain injury, subarachnoid and intracerebral hemorrhage, and large hemispheric stroke. Fever is associated with worse neurological outcome in patients with brain injury, normothermia may be of benefit in this patient population. The efficacy of mild-to-moderate hypothermia has been proven for neuroprotection after cardiac arrest with ventricular fibrillation as initial rhythm, and after neonatal asphyxia. Application of hypothermia and fever control in neurocritical care, available cooling technologies and systemic effects and complications of hypothermia will be discussed.