Initiation Of Therapeutic Hypothermia Research Articles

Servo-Controlled versus Protocol Driven Therapeutic Body Cooling on Transport

Background: Early initiation of therapeutic hypothermia (TH) for the treatment of Hypoxic Ischemic Encephalopathy (HIE) in term newborns has shown to improve outcomes. Many infants require transport into tertiary hospitals. The Tecotherm-Neo provides servo-controlled cooling compared to protocol driven use of various cooling agents. SMART Aim: By January, 2017, a protocol to recognize, initiate, and therapeutically cool infants during transport using the Tecotherm will be developed and implemented with a target temperature goal of 33-34° Celsius. Setting: Our NICU is a 71 bed Level 3 NICU that services a 100-mile …

Cerebral oxygen metabolism during and after therapeutic hypothermia in neonatal hypoxic–ischemic encephalopathy: a feasibility study using magnetic resonance imaging

Therapeutic hypothermia is the standard-of-care treatment for infants diagnosed with moderate-to-severe hypoxic-ischemic encephalopathy (HIE). MRI for assessing brain injury is usually performed after hypothermia because of logistical challenges in bringing acutely sick infants receiving hypothermia from the neonatal intensive care unit (NICU) to the MRI suite. Perhaps examining and comparing early cerebral oxygen metabolism disturbances to those after rewarming will lead to a better understanding of the mechanisms of brain injury in HIE and the effects of therapeutic hypothermia. The objectives were to assess the feasibility of performing a novel T2-relaxation under spin tagging (TRUST) MRI technique to measure venous oxygen saturation very early in the time course of treatment, 18-24h after the initiation of therapeutic hypothermia, to provide a framework to measure neonatal cerebral oxygen metabolism noninvasively, and to compare parameters between early and post-hypothermia MRIs. Early (18-24h after initiating hypothermia) MRIs were performed during hypothermia treatment in nine infants with HIE (six with moderate and three with severe HIE). Six infants subsequently had an MRI after hypothermia. Mean values of cerebral blood flow, oxygen extraction fraction, and cerebral metabolic rate of oxygen from MRIs during hypothermia were compared between infants with moderate and severe HIE; and in those with moderate HIE, we compared cerebral oxygen metabolism parameters between MRIs performed during and after hypothermia. During the initial hypothermia MRI at 23.5±5.2h after birth, infants with severe HIE had lower oxygen extraction fraction (P=0.04) and cerebral metabolic rate of oxygen (P=0.03) and a trend toward lower cerebral blood flow (P=0.33) compared to infants with moderate HIE. In infants with moderate HIE, cerebral blood flow decreased and oxygen extraction fraction increased between MRIs during and after hypothermia (although not significantly); cerebral metabolic rate of oxygen (P=0.93) was not different. Early MRIs were technically feasible while maintaining hypothermic goal temperatures in infants with HIE. Cerebral oxygen metabolism early during hypothermia is more disturbed in severe HIE. In infants with moderate HIE, cerebral blood flow decreased and oxygen extraction fraction increased between early and post-hypothermia scans. A comparison of cerebral oxygen metabolism parameters between early and post-hypothermia MRIs might improve our understanding of the evolution of HIE and the benefits of hypothermia. This approach could guide the use of adjunctive neuroprotective strategies in affected infants.

Persistent Lactic Acidosis during Therapeutic Hypothermia for Hypoxic-Ischemic Encephalopathy Predicts Adverse Outcome

Background: Prolonged lactic acidosis (LA) correlates with severe cerebral injury in asphyxiated animal models. Few studies have evaluated LA and lactate clearance in neonates undergoing therapeutic hypothermia (TH) for hypoxicischemic encephalopathy (HIE). We hypothesize that delayed normalization of serum lactate during TH reflects a more severe cerebral injury. Objective: To determine whether degree of LA prior to initiation of TH, as well as serum lactate clearance and time to normalization of serum lactate level during TH, can …

Initiation of passive cooling at referring centre is most predictive of achieving early therapeutic hypothermia in asphyxiated newborns.

To identify factors associated with early initiation and achievement of therapeutic hypothermia (TH) in newborns with hypoxic-ischemic encephalopathy (HIE). Retrospective cohort study of newborns who received TH according to National Institute of Child Health and Human Development (NICHD) criteria in two academic level 3 Neonatal Intensive Care Units (NICU) between 2009 and 2013. All infants were transported by a neonatal transport team (NNTT). Multivariate linear regression including who initiated cooling and degree of resuscitation in the model was performed. Two hundred and seven infants were included. Waiting for advice from a tertiary care NICU was independently associated with a 50 minute delay in the median time of initiation of TH. The need for extensive resuscitation (cardiopulmonary resuscitation [CPR] or epinephrine) was independently associated with a reduction of 43 minutes in the median time to reach target core temperature. Log-transformed time to initiation of TH was associated with time to reach target core temperature (P<0.001). A doubling of time to initiation of TH corresponds to a 24% (95% CI 18% to 30%) increase in median time to reach target core temperature. Initiating passive cooling at the referring centre, before transfer, is critical to faster achievement of target core temperature in asphyxiated infants. Greater outreach education and development of clinical care pathways are needed to improve optimal delivery of TH to enhance outcome.

Survey of Neonatal Intensive Care Unit Nurse Attitudes Toward Therapeutic Hypothermia Treatment

The traumatic experiences of parents of babies treated with therapeutic hypothermia (TH) have been described. No research has assessed neonatal intensive care unit (NICU) nurse experience in providing care to hypothermic babies and emotional support to their parents. To assess NICU nurse attitudes to the provision of TH with respect to perceptions about baby pain/sedation, need for nurse and parent education, decision making about initiation of TH, and barriers to best care. A survey was electronically sent to 219 nurses at 2 affiliated academic level III NICUs: 1 rural and 1 urban location. There were 17 questions where responses were selected from a preset list and 7 opportunities for nurses to provide free text responses. The response rate was 38% (N = 83). Overwhelming similarities between the urban and rural institutions were found with NICU nurses expressing understanding of the indications for initiating TH, agreement that TH improves long-term outcomes and that the benefits of TH outweigh the risks. Nurses at the urban institution more frequently expressed concerns surrounding inadequate treatment of baby pain/sedation, and nurses at both institutions strongly emphasized the need for more nurse and parent education about TH and improved timeliness of decision making for initiation of TH. NICU nurses specifically want to learn more about outcomes of babies after treatment with TH and feel that parents need more education about TH. Research is urgently needed to better understand the implications of TH treatment for parent-baby bonding.

Initiation of Therapeutic Hypothermia in the Emergency Department: A Quality Improvement Project.

Therapeutic hypothermia (TH) postresuscitation has been recommended by the American Heart Association (AHA) since 2005. Early initiation of TH and fast achievement of goal temperatures have been associated with better neurological outcomes. The objective of this study was to evaluate the effectiveness of a specific TH protocol for the emergency department (ED) in increasing ED use of TH and decreasing the time from return of spontaneous circulation (ROSC) to initiation of cooling measures. An ED protocol for TH as recommended by the AHA was implemented. A random sample of 10 patients who received TH prior to the implementation of an ED protocol were analyzed and compared with the first 10 patients who received TH after the ED protocol was implemented. The time from ROSC to initiation of cooling measures and survival to discharge rates were analyzed. After implementation of the ED protocol, 7 of the 10 patients were treated with the ED protocol. The mean time to initiation of TH for the preimplementation group was 127.8 min (SD = 52.9) compared with 15.71 min (SD = 9.552) for the postimplementation group. The difference in initiation time between the pre- and postimplementation study groups was statistically significant, t(9.826) = 6.55, p < 0.05. Survival to discharge rates were 30% for the preimplementation group and 20% for the postimplementation group. The difference was not statistically significant, χ (1, N = 20) = 0.73, p = 0.78. Implementation of an ED protocol for TH reduced mean time to initiation of therapy. Additional study is warranted to determine whether differences in survival and functional recovery for ED patients receiving TH were influenced by age, comorbidities, and total resuscitation time.

Achieving Optimal Therapeutic Hypothermia on Transport

Early initiation of therapeutic hypothermia (TH) for the treatment of hypoxic ischemic encephalopathy (HIE) has been shown to improve outcomes. Many of these patients require transport to treatment facilities. At the time of the study, there were no servo-controlled devices approved for flight that allowed for active cooling of the neonate during air transport. To introduce a clinical bundle for safe, active, or passive cooling and to achieve targeted, accurate temperature control with application for air or ground transport. After meeting criteria, a facsimile is sent to the referring center with instructions for passive cooling. Strict protocols are initiated, guiding the transport team in reaching and maintaining target temperature range of 33°C to 35°C. From June 2010 to January 2014, a total of 22 neonates who qualified for TH were transported using the care bundle. Eight were actively cooled, whereas 14 were passively cooled. Of note, 8 infants required warming for temperatures below the acceptable range. The average temperature before turning off the warmer at the referral center was 36.0°C (SD = 1.1). The average temperature upon arrival of the transport team was 34.9°C (SD = 1.4). The average temperature upon arrival to the receiving facility was 33.5°C (SD = 0.7). By utilizing a care bundle for the initiation of TH on transport, neonates can be safely delivered to a treatment center with an average temperature well within treatment range, all while avoiding extreme fluctuations. The number of qualified participants limited the study. Future research should focus on the effectiveness of the bundle in larger treatment populations, with inclusion of additional transport teams.

Extended Use of Hypothermia in Elderly Patients with Malignant Cerebral Edema as an Alternative to Hemicraniectomy.

Background and PurposeThe use of decompressive hemicraniectomy (DHC) for the treatment of malignant cerebral edema can decrease mortality rates. However, this benefit is not sufficient to justify its use in elderly patients. We investigated the effects of therapeutic hypothermia (TH) on safety, feasibility, and functional outcomes in elderly patients with malignant middle cerebral artery (MCA) infarcts.MethodsElderly patients 60 years of age and older with infarcts affecting more than two-thirds of the MCA territory were included. Patients who could not receive DHC were treated with TH. Hypothermia was started within 72 hours of symptom onset and was maintained for a minimum of 72 hours with a target temperature of 33°C. Modified Rankin Scale (mRS) scores at 3 months following treatment and complications of TH were used as functional outcomes.ResultsEleven patients with a median age of 76 years and a median National Institutes of Health Stroke Scale score of 18 were treated with TH. The median time from symptom onset to initiation of TH was 30.3±23.0 hours and TH was maintained for a median of 76.7±57.1 hours. Shivering (100%) and electrolyte imbalance (82%) were frequent complications. Two patients died (18%). The mean mRS score 3 months following treatment was 4.9±0.8.ConclusionsOur results suggest that extended use of hypothermia is safe and feasible for elderly patients with large hemispheric infarctions. Hypothermia may be considered as a therapeutic alternative to DHC in elderly individuals. Further studies are required to validate our findings.

An Assessment of Emergency Department Post-Cardiac Arrest Care Variation in Michigan.

Implementation of postarrest care by individual physicians and systems has been slow. Deadoption, or discontinuation of therapeutic hypothermia (TH) treatment targets, after recent prospective study results has not been well reported. This study assesses practices in the early stages of postarrest care across emergency departments (EDs) in Michigan. A 27-question Internet-based survey was distributed to EDs in Michigan in September 2013. To assess changes in practice after publication of Nielsen et al., we sent follow-up questions to all original respondents a year later. Observational data and descriptive statistics are reported. From the 142 EDs identified, we excluded critical access hospitals (N = 35), free standing EDs (N = 7), EDs that transfer critical patients to tertiary centers (N = 21), and exclusive children's hospitals (N = 3). Of the remaining 76 hospitals, we received 64 (84.2%) responses. We identified 15 respondents with a protocol to specifically initiate ED TH and transfer patients to a higher level of care. The 49 remaining were mostly teaching institutions (N = 34, 69%) and gave the ED physician the ability to initiate TH (N = 40, 82%). On follow-up 12 months later, we received 33/40 (83%) responses, of which only 5 indicated formal or informal change in TH practice or target temperature. There is substantial variation in the practice of ED postarrest care and initiation of TH across the state of Michigan, but few ED TH protocols were changed in a year's time. The consequences of postarrest treatment variability at the state and ED levels are likely under-recognized as an influence on outcome variation between regions.

Abstract 18724: Coronary Angiography After Out-of-hospital Cardiac Arrest is Associated With Improved Neurologically Intact Survival

Introduction: Evidence for the effectiveness of coronary angiography after out-of-hospital cardiac arrest (OHCA) is conflicting. Our objective was to evaluate the association between receiving coronary angiography within 72 hours of hospital arrival and survival with favorable neurologic outcome. Methods: This was a population-based retrospective cohort study of consecutive cases of adult OHCA transported to and treated at 28 hospitals in Southern Ontario between March 1, 2010 and December 31, 2014. We included patients with atraumatic OHCA, who achieved return of spontaneous circulation, and were alive 6 hours after hospital arrival. Multi-level logistic regression was used to measure the association between early coronary angiography and neurologically intact survival (Modified Rankin Score 0-2), while controlling for potential confounders and clustered data. We controlled for age, sex, initial cardiac rhythm, witness status, bystander resuscitation, EMS response time, prehospital return of spontaneous circulation, location of arrest, daytime presentation, neurologic status at hospital arrival, STEMI status, cardiac history, initiation of therapeutic hypothermia, hospital size and type, and hospital annual cardiac arrest volume. Results: During the period of study, 2678 consecutive OHCA patients met the inclusion criteria. The mean age was 66(±16), 31.7% were female, 54.1% had a bystander witnessed arrest, 35.2% received bystander CPR, 45.9% had a shockable initial rhythm, 30.1% had ST elevation on the first post arrest ECG, and 32.4% received coronary angiography. Receiving coronary angiography was strongly associated with neurologically intact survival (OR 2.30, CI95 1.69-3.15) and survival (OR 2.08, CI95 1.53-2.82). A similar association was observed in the subgroup of patients without STEMI (OR 3.24, CI95 2.16-4.87 and OR 2.66, CI95 1.78-3.99, respectively). Conclusions: Neurologically intact survival among post cardiac arrest patients may be improved with coronary angiography, particularly for patients without STEMI. This observation should be confirmed with future randomized controlled studies.

Abstract 18554: Patient, Cardiac Arrest and Hospital Characteristics That Predict Receipt of Coronary Angiography in Out-of-Hospital Cardiac Arrest Patients

Introduction: Previous studies have suggested an association between coronary angiography and improved outcomes amongst post cardiac arrest patients. Our objective was to measure the association between patient and hospital-level characteristics and receipt of coronary angiography to generate hypotheses to inform a definitive trial. Methods: This was a population-based retrospective cohort study of data from 28 hospitals in Southern Ontario between March 1, 2010 and December 31, 2014. We included consecutive adult patients with atraumatic, OHCA, who achieved return of spontaneous circulation, and were alive 6 hours after hospital arrival. Multi-level logistic regression was used to measure the relationship between patient and hospital-level covariates and receipt of coronary angiography, adjusted for clustering and potential confounders. Results: During the period of study, 2678 consecutive patients met the inclusion criteria; mean age 66(±16), 68.3% male, 45.9% shockable initial rhythm, 84.2% comatose at hospital admission. Overall, 32.4% received coronary angiography and 21.8% received percutaneous coronary intervention (PCI). Coronary angiography use varied from 12.7% to 63.6% across the sites. Factors significantly associated with receiving coronary angiography included ST-elevation (OR=23.31, CI95 17.64-30.80), being comatose at hospital arrival (OR=0.15, CI95 0.10-0.23), shockable initial cardiac rhythm (OR=4.87, CI95 3.70-6.41), bystander AED use (OR=2.05, CI95 1.21-3.47), EMS-witnessed arrest (OR=1.80, CI95 1.16-2.78), initiation of therapeutic hypothermia (OR=1.96, CI95 1.38-2.79), initial admission to a PCI centre (OR=3.20, CI95 1.78-5.76), male sex (OR=1.43, CI95 1.07-1.90) and age (OR=0.98, CI95 0.97-0.99). Conclusions: There is significant variability in receipt of coronary angiography after cardiac arrest. We identified several patient and hospital-level factors that contribute to this variability. Future work should determine which post arrest patients will benefit most from urgent angiography and develop and evaluate knowledge translation strategies to ensure consistent delivery of best practices.

PERCUTANEOUS CORONARY INTERVENTION IS ASSOCIATED WITH UNNECESSARY DELAYS IN INITIATION OF MILD THERAPEUTIC HYPOTHERMIA IN PATIENTS WITH CARDIAC ARREST

INTRODUCTION: Mild therapeutic hypothermia (TH) has been found effective in improving neurological prognosis of comatose patient after cardiac arrest (CA). Delay in initiating TH has been associated with poor neurological outcomes. Cardiac catheterization (CC) is often performed in patients with CA. The impact of CC on timing of TH and the ideal timing of CC in patients with CA need further evaluation. METHOD: We conducted a retrospective study including all patients who underwent TH after CA between November 1st 2009 and October 20th 2012 in a tertiary care center with PCI facilities. Patients were separated in two groups based on delay of initiation of TH from CA ( 180 min). We identified factors associated with delay in initiating TH using logistic regression. RESULTS: Forty-two patients underwent TH during the study period. Two patients were excluded because of missing values. Selected patient characteristics are shown in the Table. TH was initiated in the referral hospital in 5 (12%) patients. Median time of initiation of TH from CA was 205 (169, 297) minutes. Performing imaging tests before cooling was associated with delayed initiation of TH: cardiac ultrasound (329 222 versus 204 82 minutes; p 1⁄4 0.01), computerized tomography scan (309 208 versus 202 77 minutes; p 1⁄4 0.02). On average, initiation of TH was delayed for 61 min in patients undergoing CC first when compared to patients who were cooled first (268 min vs 207 min). After exclusion of patients in whom TH was initiated in the referral hospital, factors independently associated with delay in initiation of TH of> 180 min were: presentation during daytime (p1⁄40.002), being transferred from a referral hospital (p1⁄40.04) and undergoing CC before TH (p1⁄40.06). TH was initiated immediately prior to CC in 6 patients. Time to reach target temperature was longer in these patients compared to other patients (215 min vs 128 min; p1⁄40.03). No ischemic complication was reported in patients undergoing PCI during TH. Overall, inhospital mortality was 50%. In survivors, neurological outcome was good (CPC 1 or 2) in 17 out of 20 patients. CONCLUSION: In this single-center registry of patients sustaining a CA, CC was associated with a substantial delay in initiation of TH. Cooling at the time of CC was feasible and while it lengthens the time to reach target temperature, it was not associated with adverse ischemic outcomes.

In vivo Monitoring of Cerebral Hemodynamics in the Immature Rat: Effects of Hypoxia-Ischemia and Hypothermia

Background: Neonatal hypoxic-ischemic (HI) encephalopathy occurs in 1-4 per 1,000 live term births and can cause devastating neurodevelopmental disabilities. Currently, therapeutic hypothermia (TH) is the only treatment with proven efficacy. Since TH is associated with decreased cerebral metabolism and cerebral blood flow (CBF), it is important to assess CBF at the bedside. Diffuse correlation spectroscopy (DCS) has emerged as a promising optical modality to noninvasively assess an index of CBF (CBF_i) in both humans and animals. In this initial descriptive study, we employ DCS to monitor the evolution of CBF_i following HI with or without TH in immature rats. We investigate potential relationships between CBF and subsequent cerebral damage. Methods: HI was induced on postnatal day 10 or 11 rat pups by right common carotid artery ligation followed by 60-70 min hypoxia (8% oxygen). After HI, the pups recovered for 4 h under hypothermia (HI-TH group, n = 23) or normothermia (HI-N group, n = 23). Bilateral measurements of hemispheric CBF_i were made with DCS in unanesthetized animals at baseline, before HI, and 0, 1, 2, 3, 4, 5, and 24 h after HI. The animals were sacrificed at either 1 or 4 weeks, and brain injury was scored on an ordinal scale of 0-5 (0 = no injury). Results: Carotid ligation caused moderate bilateral decreases in CBF_i. Following HI, an initial hyperemia was observed that was more prominent in the contralateral hemisphere. After initiation of TH, CBF_i dropped significantly below baseline levels and remained reduced for the duration of TH. In contrast, CBF_i in the HI-N group was not significantly decreased from baseline levels. Reductions in CBF_i after 4 h of TH were not associated with reduced damage at 1 or 4 weeks. However, elevated ipsilateral CBF_i and ipsilateral-to-contralateral CBF_i ratios at 24 h were associated with worse outcome at 1 week after HI. Conclusions: Both HI and TH alter CBF_i, with significant differences in CBF_i between hypothermic and normothermic groups after HI. CBF_i may be a useful biomarker of subsequent cerebral damage.

Higher achieved mean arterial pressure during therapeutic hypothermia is not associated with neurologically intact survival following cardiac arrest

IntroductionTo determine if higher achieved mean arterial blood pressure (MAP) during treatment with therapeutic hypothermia (TH) is associated with neurologically intact survival following cardiac arrest. MethodsRetrospective analysis of a prospectively collected cohort of 188 consecutive patients treated with TH in the cardiovascular intensive care unit of an academic tertiary care hospital. ResultsNeurologically intact survival was observed in 73/188 (38.8%) patients at hospital discharge and in 48/162 (29.6%) patients at a median follow up interval of 3 months. Patients in shock at the time of admission had lower baseline MAP at the initiation of TH (81 versus 87mmHg; p=0.002), but had similar achieved MAP during TH (80.3 versus 83.7mmHg; p=0.11). Shock on admission was associated with poor survival (18% versus 52%; p<0.001). Vasopressor use among all patients was common (84.6%) and was not associated with increased mortality. A multivariable analysis including age, initial rhythm, time to return of spontaneous circulation, baseline MAP and achieved MAP did not demonstrate a relationship between MAP achieved during TH and poor neurological outcome at hospital discharge (OR 1.28, 95% CI 0.40–4.06; p=0.87) or at outpatient follow up (OR 1.09, 95% CI 0.32–3.75; p=0.976). ConclusionWe did not observe a relationship between higher achieved MAP during TH and neurologically intact survival. However, shock at the time of admission was clearly associated with poor outcomes in our study population. These data do not support the use of vasopressors to artificially increase MAP in the absence of shock. There is a need for prospective, randomized trials to further define the optimum blood pressure target during treatment with TH.

Abstract 164: Antithrombotic Use and Bleeding in Patients Receiving Therapeutic Hypothermia

Background: The known anticoagulant effects of hypothermia poses challenges when considering therapeutic hypothermia (TH) after cardiac arrest, including the risk of bleeding and the safety of giving concomitant antiplatelet and anticoagulation therapy. We therefore examined antithrombotic use and the risk of bleeding in patients receiving TH. Methods: In a large tertiary academic center in Boston, we examined the incidence of bleeding in patients evaluated for TH. Antiplatelet therapy and anticoagulation (oral or parenteral) prior to arrest and during the hospitalization were recorded. Results: TH was initiated in 190 patients and completed in 150. Among 40 patients in which TH was stopped early, bleeding was cited as a reason in 5 (though in 3 cases bleeding was documented at time of TH initiation). Of the 150 ‘completers’, 16 (10.6%) bled during TH. Bleeding was present at the time of TH initiation in 8/16 patients. Bleeding sites were most commonly GI 56.3% and vascular access 25% with no cases of intracranial bleeding. Presenting rhythm, survival, neurological outcomes and inpatient administration of antiplatelet and anticoagulation medications were similar between the bleeding and non-bleeding groups. Though there was no significant hematocrit change in the two groups, more patients with bleeding received red blood cell (RBC) transfusions (56.3% vs 2.2%) and received more RBC units (5.4±5.4 vs 1.3±0.5 p=0.054). Of the 15 patients on mechanical circulatory support, only 4 had a bleeding event during TH. Conclusion: There were no significant differences between the bleeding and non-bleeding groups during TH in terms of concomitant antithrombotic agents or neurologic recovery/survival. These findings suggest that the incidence of bleeding in TH is acceptable and that it is safe to treat patients with antithrombotics and mechanical circulatory devices as clinically indicated.

Abstract 317: Effect of Intra-arrest Induction of Therapeutic Hypothermia on Out-of-Hospital Cardiac Arrest

Introduction: The resuscitation literature has recently suggested that the prehospital initiation of therapeutic hypothermia following successful resuscitation does not alter outcomes among patients who suffer sudden out-of-hospital cardiac arrest (OOHCA). We sought to assess the impact of earlier, intra-arrest induction of therapeutic hypothermia on OOHCA survival. Methodology: Out-of-hospital cardiac arrest data from two consecutive twelve-month periods was analyzed: August 1, 2009 - July 31, 2010 (Phase I), August 1, 2010 - July 31, 2011 (Phase II). In Phase I, paramedics in this urban system transported OOHCA patient to participating Cardiac Arrest Centers where the use of therapeutic hypothermia had been incorporated to the standard post-resuscitation care pathway. In Phase II, paramedics initiated hypothermia during the initial resuscitation effort through the rapid infusion of large-volume, ice-cold saline. Consistent with the Utstein definitions, analyses utilized only those cases which were bystander witnessed and of cardiac etiology. Results: There were 1,487 and 850 bystander witnessed arrests of cardiac etiology in the two phases. Patient and arrest characteristics for the two groups did not differ with respect to age, gender, race, response time, bystander witnessed status, or the frequency of bystander CPR. Return of spontaneous circulation (ROSC), sustained ROSC, survival to hospital admission and survival to hospital discharge did not differ significantly from Phase I to Phase II: 40.82% vs 39.59% (p=.54), 31.10% vs 31.17% (p=0.58), 27.15% vs 24.88% (p=0.27), and 6.62% vs 6.19% (p=0.41). In addition, among those survivors for whom neurologic status is known, the intra-arrest initiation of therapeutic hypothermia did not significantly change the proportion of survivors considered neurologically intact (76.47% vs 70.37%, all p=0.59). Conclusions: The intra-arrest initiation of therapeutic hypothermia did not alter outcomes among OOHCA patients, demonstrating neither harm nor benefit. Whether this is due to a lack of continuation of hypothermia following hospital admission or a true lack of benefit requires further collaborative work between the prehospital and hospital communities.

Abstract 324: Assessment in Therapeutic Hypothermia Protocol: A Quality Assessment Initiative and Analysis of Hemodynamic and Laboratory Parameters

Background: Therapeutic hypothermia (TH) is often considered for comatose patients with return of spontaneous circulation after cardiac arrest (CA). While patients undergoing out-of-hospital ventricular fibrillation cardiac arrest are thought to benefit most from TH, the individualized benefit of initiating TH is unknown. Using a combination of clinical and laboratory parameters at presentation, we sought a model to predict survival and discharge to home. Methods: We performed a retrospective study of patients undergoing TH after CA at the University of Kentucky Hospital from 4/1/11 to 12/31/13. Records confirmed by chart review. The primary outcomes were discharge disposition and death. We conducted logistic regression analyses to identify predictors of home discharge and survival. Results: The series included 80 patients (mean±SD age was 55.2±14.9, and 61% were male). The overall mortality rate was 67.9% with survivor home discharge disposition of 21.2%. The Apache II Score (estimated odds ratio [OR] 1.167) was a significant predictor of death; moreover, though not itself a significant predictor of death, troponin improved the ability of Apache II to predict death. The Apache II Score (OR 0.882) and Mean Arterial Pressure (OR 1.049) were significant predictors of home discharge. Figures 1 and 2 display estimated probabilities of survival and home discharge based on two-predictor logistic regression models. Conclusions: In patients undergoing TH, a favorable prognosis is anticipated given certain values for hemodynamic and laboratory parameters. Thus, the patient’s clinical presentation may provide additional guidance when considering initiation of TH after CA.

Abstract 19708: Pre-Hospital Initiation of Therapeutic Hypothermia Associated With Better Survival and Neurologic Outcome in a Broad Population of Patients in North Carolina

Introduction: Out-of-hospital cardiac arrest (OHCA) has less than 10% hospital survival. While therapeutic hypothermia resulted in a 16%-24% improvement in neurologic outcome in patients with ventricular fibrillation (VF) in prior trials, recent trials have not shown benefit of pre-hospital initiation hypothermia or of hospital cooling to 33 vs 36 degrees. Methods: We studied patients who suffered OHCA in North Carolina from 2012-2013 captured in the CARES database as part of the Heart Rescue Project. To limit selection bias, we excluded patients without return of spontaneous circulation after arrest and without intubation in the field as they may have regained consciousness. Results: 847 patients were included in the analysis of pre-hospital hypothermia. The patients that received pre-hospital hypothermia had more bystander initiated CPR (p-value &lt; 0.45). Pre-hospital hypothermia was associated with a significant increase in survival to hospital discharge (OR 1.55, 95% CI 1.03-2.32) and neurologic outcome at discharge (OR 1.56 95% CI 1.01-2.40). When looking at arrest types, the significant association was seen after VF arrest (figure). 537 patients survived to hospital admission and included in the analysis of in-hospital hypothermia. Patients who received hospital hypothermia were younger, had more VF, more witnessed arrest and more pre-hospital hypothermia. Hypothermia showed a non-significant trend toward better survival to discharge. Conclusions: The association between pre-hospital hypothermia after VF arrest and improved survival, in light of randomized data showing no effect, may be due to confounding or to a greater likelihood of in-hospital hypothermia in this group. The trend in better outcome using in-hospital hypothermia is consistent with a benefit from temperature management. These findings suggest the need for ongoing efforts to understand the value of hypothermia in context of other efforts to improve survival from cardiac arrest.

Serial hemodynamic measurements in post-cardiac arrest cardiogenic shock treated with therapeutic hypothermia.

Mortality from cardiogenic shock complicating acute myocardial infarction (MI) remains high despite contemporary treatment. Therapeutic Hypothermia (TH) offers cardiovascular and systemic effects that may prove beneficial in this population, however, current data are limited. This study sought to evaluate the effect of therapeutic hypothermia on serial hemodynamics obtained in subjects with post-cardiac arrest cardiogenic shock. We analyzed serial hemodynamics of 14 consecutive patients with cardiogenic shock after cardiac arrest treated with TH. Study inclusion required baseline hemodynamics obtained prior to initiation of TH confirming cardiogenic shock defined as cardiac index ≤2.2 L/min/m(2) with a systolic blood pressure of ≤90 mmHg, a vasopressor requirement, or need for mechanical circulatory support. In our 14 patients, the mean age was 58 ± 13.1 years, mean ejection fraction was 21 ± 8%, six had an acute MI, 12 required vasopressors, and 10 required mechanical support prior to initiation of TH. When compared to baseline, patients had significant improvements in Fick cardiac index, mixed venous O2 saturations, and serum lactate concentrations while heart rate was reduced following initiation of TH. There was no significant change in mean arterial pressure, however vasopressor requirement was reduced. In patients with cardiogenic shock following cardiac arrest, initiation of TH was associated with favorable changes in invasive hemodynamics suggesting safety in this population. Given potential for favorable hemodynamic and systemic effects of TH in cardiogenic shock, further prospective study of TH as a potentially novel adjunctive therapy to early reperfusion in post-MI cardiogenic shock should be considered.

Hyperglycemia and insulin resistance in cardiac arrest patients treated with moderate hypothermia.

It is unknown whether the hyperglycemia that follows cardiac arrest and during therapeutic hypothermia (TH) is due to the arrest or the TH, whether it is associated with adverse outcomes, or whether its treatment affects outcomes. The objective of the study was to determine the effects of TH on the blood glucose (BG) levels in postcardiac arrest patients and the effects of hyperglycemia on mortality. This was a chart review of 62 patients undergoing TH after cardiac arrest between September 2005 and April 2008. BG levels from 72 hours before the arrest to 48 hours after TH and iv insulin infusion rates were analyzed and correlated with survival to discharge from hospital. The study was conducted at a tertiary, university referral center. PATIENTS undergoing TH after cardiac arrest participated in the study. TH consisted of cooling as rapidly as possible to 33°C, holding that temperature for 24 hours, and then controlled rewarming to 37°C over 8 or 16 hours. Hyperglycemia was managed with iv insulin drip protocols. The relationship of cardiac arrest and hypothermia to hyperglycemia, with a key secondary outcome being the relationship of hyperglycemia to survival to discharge, was measured. Analysis of glucose patterns showed no independent effect of TH on BG levels. Mean BG levels between cardiac arrest and the initiation of hypothermia were higher in nonsurvivors (253 ± 112 mg/dL, n = 48) than in survivors (192 ± 69 mg/dL, n = 24, P = .016). BG, insulin infusion rates, and insulin resistance during hypothermia, during rewarming, and 24-48 hours after hypothermia were not significantly different between the 2 groups. In patients treated with TH, the TH had no independent effect on BG levels. Mortality was associated with increased BG levels after cardiac arrest but before initiation of TH or an insulin drip. Likely, it is the severity of stress from the cardiac arrest that causes the hyperglycemia in these patients.