Rebound Hyperthermia Research Articles

Rebound Hyperthermia in Exertional Heat Stroke.

Exertional heat stroke (EHS) is a life-threatening condition requiring rapid reversal of hyperthermia to prevent poor health outcomes. Current treatment protocols aim for a cooling rate of 0.15 C/min using various modalities. This case report details a 22-year-old male who, despite initial successful cooling measures, experienced rebound hyperthermia, necessitating the use of endovascular cooling (EVC). The patient collapsed during a 19.3 km (12-mile) ruck march in Fort Moore, Georgia, with an initial core temperature of 41.6ºC. Conventional cooling methods, including ice sheets and chilled intravenous saline, adequately cooled the patient to target temperatures; however, discontinuation of cooling methods resulted in rebound hyperthermia. Endovascular cooling was eventually initiated, resulting in euthermia after 36 hours of continued use. During his hospital admission, the patient was evaluated thoroughly for underlying etiologies contributing to his rebound hyperthermia. This workup did not yield any concerning pathology, except for bilateral foot cellulitis noted on physical examination, which was subsequently managed with antibiotics. Despite initial complications, the patient recovered within 5 days and returned to duty after 2 months. Several case reports have been published regarding the use of EVC in the management of EHS. These reports, however, describe its use in initial management of EHS or in cases where hyperthermia was refractory to other conventional cooling methods. To our knowledge, this is the first report of its kind highlighting its successful implementation in rebound hyperthermia. Early recognition and initiation of cooling measures are critical in EHS cases. Future directions include developing EHS-specific EVC protocols for patients experiencing refractory or rebound hyperthermia.

Comparison of Clinical Outcomes between Rebound Hyperthermia and Non-Rebound Hypertherma Groups in Postcardiac Arrest Syndrome Patients Undergoing Targeted Temperature Management

Purpose : This retrospective study aims to provide basic data for intervention to improve clinical outcomes and identify the characteristics of the rebound hyperthermia (RHG) and non-rebound hyperthermia (NRHG) groups by checking body temperature in patients with post-cardiac arrest syndrome.Method : The study involved 118 patients who completed target temperature management (TTM) in an acute-care unit. Data were analyzed for frequency, percentages, mean, standard deviation, median, and quartiles, and compared using the chi-squared test and Mann–Whitney U-test.Results : Rebound hyperthermia (RH) was observed in 74 (62.7%) patients, predominantly male (69.5%), with an average age of 64.54 ± 15.98, and a body mass index of 23.22 ± 4.75kg/m<sup>2</sup> (overweight). Hypertension (50%) was the most common co-morbidity, followed by diabetes and heart disease (33.1%). Neuron-specific enolase levels were higher in the NRHG 24, 48, and 72 hours after recovery of spontaneous circulation (p = .037, <i>p</i>＜ .001, <i>p</i>= .008). The APHCHE Ⅳ was also higher in the NRHG (<i>p</i>＜ .001). RH occurred 25.49 (7.28–52.96) hours after TTM completion, lasting for 2 (1–3) hours. Temperature reduction strategies included notifying doctors, administering antipyretics, and nursing intervention, with the latter being the most common at 94.6%. Half of the subjects in the RHG and 77.3% in the NRHG fell into cerebral performance categories 3, 4, and 5 (<i>p</i>= .003).Conclusion : RH is more likely a body mechanism related to CPR and TTM than a result of pathogenic infection. Therefore, we require an active intervention for hyperthermia, and a patient-specific nursing intervention protocol.

A Systematic Literature Review to Assess Fever Management and the Quality of Targeted Temperature Management in Critically Ill Patients.

Targeted temperature management (TTM) has been proposed to reduce mortality and improve neurological outcomes in postcardiac arrest and other critically ill patients. TTM implementation may vary considerably among hospitals, and "high-quality TTM" definitions are inconsistent. This systematic literature review in relevant critical care conditions evaluated the approaches to and definitions of TTM quality with respect to fever prevention and the maintenance of precise temperature control. Current evidence on the quality of fever management associated with TTM in cardiac arrest, traumatic brain injury, stroke, sepsis, and critical care more generally was examined. Searches were conducted in Embase and PubMed (2016 to 2021) following PRISMA guidelines. In total, 37 studies were identified and included, with 35 focusing on postarrest care. Frequently-reported TTM quality outcomes included the number of patients with rebound hyperthermia, deviation from target temperature, post-TTM body temperatures, and number of patients achieving target temperature. Surface and intravascular cooling were used in 13 studies, while one study used surface and extracorporeal cooling and one study used surface cooling and antipyretics. Surface and intravascular methods had comparable rates of achieving target temperature and maintaining temperature. A single study showed that patients with surface cooling had a lower incidence of rebound hyperthermia. This systematic literature review largely identified cardiac arrest literature demonstrating fever prevention with multiple TTM approaches. There was substantial heterogeneity in the definitions and delivery of quality TTM. Further research is required to define quality TTM across multiple elements, including achieving target temperature, maintaining target temperature, and preventing rebound hyperthermia.

Targeted temperature management after cardiac arrest : What is new?

The current guidelines of the European Resuscitation Council recommend targeted temperature management to improve functional neurological outcome in comatose survivors after cardiac arrest. With the pathophysiological background of hypothermia-induced neuroprotection for prevention of hypoxic-ischemic encephalopathy, targeted temperature management is akey measure and represents acentral aspect in postresuscitation care.In the 2021 guidelines the application of targeted temperature management in postresuscitation care has been recommended for all rhythms and irrespective of the location of cardiac arrest. Targeted temperature management is advocated for adult patients who remain unresponsive following return of spontaneous circulation (ROSC) after either out-of-hospital cardiac arrest or in-hospital cardiac arrest. The body temperature should be maintained at aconstant value between 32 °C and 36 °C for at least 24 h. To avoid rebound hyperthermia, fever following targeted temperature management, defined as atemperature above 37.7 °C, should be prevented and treated for at least 72 h after ROSC in persistently comatose patients. The routine use of prehospital cooling by rapid infusion of large volumes of cold i.v. fluid immediately after ROSC is not recommended.Based on asystematic review of the current literature, this article summarizes the results of randomized trials and new findings on targeted temperature management in comatose adult patients after cardiac arrest. The review has aparticular focus on the most recent evidence regarding the optimum range of target temperatures. Furthermore, recent data on preclinical management, different patient populations, the duration of targeted temperature management, cooling methods and rebound hyperthermia are discussed.The impact of targeted temperature management on neurological outcome after cardiac arrest has been amatter of controversy. Despite contradictory results and heterogeneity of study designs, the current evidence supports the relevance and the necessity of strict temperature control in postresuscitation care for neuroprotection and improvement in functional neurological outcomes.

Factors Associated With Rebound Hyperthermia After Targeted Temperature Management in Out-of-Hospital Cardiac Arrest Patients: An Explorative Substudy of the Time-Differentiated Therapeutic Hypothermia in Out-of-Hospital Cardiac Arrest Survivors Trial

Post hoc analysis. Ten European ICUs. Patients included in the time-differentiated therapeutic hypothermia in out-of-hospital cardiac arrest survivors trial treated with targeted temperature management at 33°C for 48 or 24 hours. Favorable functional outcome was defined as a Cerebral Performance Category of 1 or 2 at 6 months. None. Of 338 included patients, 103 (30%) experienced rebound hyperthermia defined as a maximum temperature after targeted temperature management and rewarming exceeding 38.5°C. Using multivariate logistic regression analysis, increasing age (odds ratio, 0.97; 95% CI, 0.95-0.99; p = 0.02) and severe acute kidney injury within 72 hours of ICU admission (odds ratio, 0.35; 95% CI, 0.13-0.91; p = 0.03) were associated with less rebound hyperthermia, whereas male gender (odds ratio, 3.94; 95% CI, 1.34-11.57; p = 0.01), highest C-reactive protein value (odds ratio, 1.04; 95% CI, 1.01-1.07; p = 0.02), and use of mechanical chest compression during cardiopulmonary resuscitation (odds ratio, 2.00; 95% CI, 1.10-3.67; p = 0.02) were associated with more rebound hyperthermia. Patients with favorable functional outcome spent less time after rewarming over 38.5°C (2.5% vs 6.3%; p = 0.03), 39°C (0.14% vs 2.7%; p < 0.01), and 39.5°C (0.03% vs 0.71%; p < 0.01) when compared with others. Median time to rebound hyperthermia was longer in the unfavorable functional outcome group (33.2 hr; interquartile range, 14.3-53.0 hr vs 6.5 hr; interquartile range, 2.2-34.1; p < 0.01). In a predefined multivariate binary logistic regression model, rebound hyperthermia was associated with decreased odds of favorable functional outcome (odds ratio, 0.42; 95% CI, 0.22-0.79). One-third of targeted temperature management patients experience rebound hyperthermia, and it is more common in younger male patients with an aggravated inflammatory response and those treated with a mechanical chest compression device. Later onset of rebound hyperthermia and temperatures exceeding 38.5°C associate with unfavorable outcome.

The impact of therapeutic hypothermia in elderly out-of-hospital cardiac arrest: A multicenter retrospective observational propensity-matched study

Background: The therapeutic hypothermia protocol for out of hospital cardiac arrest is not standardized and the decision to apply therapeutic hypothermia relies on a physician’s judgment. Elderly patients who rely on this judgment are less likely to receive therapeutic hypothermia. Objectives: This study aimed to provide an analysis of the impact and utility of therapeutic hypothermia on elderly out of hospital cardiac arrest. Methods: This was a multicenter, retrospective, observational, registry-based study from 2007 to 2012. Adults who suffered out-of-hospital cardiac arrest and were treated with therapeutic hypothermia were included. We divided the patients into a group of elderly patients 65 years or older and a group of young adults under 65 years old and compared the neurologic outcomes and adverse events after one-to-one matching by propensity score. Results: In total, 930 patients were enrolled in the study. Among these patients, 343 were ⩾65 years, while 587 were &lt;65 years. Of the adverse events in therapeutic hypothermia, hyperglycemia (51.31%), hypotension (41.98%) during cooling was more frequent in aged ⩾65 years and rebound hyperthermia (7.14%) and hypotension (29.93%) during rewarming. After propensity score matching was applied to all subjects of the study, 247 matched pairs of patients were available. The two groups showed no statistically significant difference in the adverse events during therapeutic hypothermia. Conclusion: Elderly patients exhibited a decreased survival to hospital discharge and good neurologic outcomes. The two groups showed no differences in the frequency of adverse events during therapeutic hypothermia, when comparing in a propensity score matching cohort analysis.

Clinical Effect of Rebound Hyperthermia After Cooling Postcardiac Arrest: A Meta-Analysis.

Rebound hyperthermia (RH) is frequently seen after completion of targeted temperature management (TTM) in comatose survivors of cardiac arrest. However, its clinical significance is not well understood. Previous studies analyzing the association of RH with clinical outcome have reported conflicting results. The purpose of this meta-analysis is to examine the impact of RH after completion of TTM in patients postcardiac arrest. We reviewed six studies that evaluated the incidence of RH (T > 38°C) with documentation of outcome based on the presence of hyperthermia. We reviewed all six articles and extracted the data for mortality and neurological outcome. A total of 729 patients were analyzed for neurological outcome and 950 patients were analyzed for mortality. RH was found to be associated with a significantly worse neurological outcome (odds ratio [OR] 1.55; 95% confidence interval [CI] 1.13-2.14). RH was not significantly associated with a higher mortality (OR 1.31; 95% CI 1.00-1.72). We also analyzed three studies totaling 206 patients for neurological outcomes and mortality that included patients with severe RH (T > 38.5°C). Severe RH was found to be associated with significantly worse neurological outcome (OR 1.92, 95% CI 1.28-1.90) and significantly worse mortality (OR 2.22, 95% CI 1.50-3.29). RH is common after completion of TTM in comatose patients because of cardiac arrest and is associated with poor neurological outcomes. The clinical impact of RH is likely proportional to the magnitude of RH.

Randomized controlled trial of internal and external targeted temperature management methods in post- cardiac arrest patients

BackgroundTargeted temperature management post-cardiac arrest is currently implemented using various methods, broadly categorized as internal and external. This study aimed to evaluate survival-to-hospital discharge and neurological outcomes (Glasgow-Pittsburgh Score) of post-cardiac arrest patients undergoing internal cooling verses external cooling. MethodologyA randomized controlled trial of post-resuscitation cardiac arrest patients was conducted from October 2008–September 2014. Patients were randomized to either internal or external cooling methods. Historical controls were selected matched by age and gender. Analysis using SPSS version 21.0 presented descriptive statistics and frequencies while univariate logistic regression was done using R 3.1.3. Results23 patients were randomized to internal cooling and 22 patients to external cooling and 42 matched controls were selected. No significant difference was seen between internal and external cooling in terms of survival, neurological outcomes and complications. However in the internal cooling arm, there was lower risk of developing overcooling (p=0.01) and rebound hyperthermia (p=0.02). Compared to normothermia, internal cooling had higher survival (OR=3.36, 95% CI=(1.130, 10.412), and lower risk of developing cardiac arrhythmias (OR=0.18, 95% CI=(0.04, 0.63)). Subgroup analysis showed those with cardiac cause of arrest (OR=4.29, 95% CI=(1.26, 15.80)) and sustained ROSC (OR=5.50, 95% CI=(1.64, 20.39)) had better survival with internal cooling compared to normothermia. Cooling curves showed tighter temperature control for internal compared to external cooling. ConclusionInternal cooling showed tighter temperature control compared to external cooling. Internal cooling can potentially provide better survival-to-hospital discharge outcomes and reduce cardiac arrhythmia complications in carefully selected patients as compared to normothermia.

Comparison of Two Surface Cooling Devices for Temperature Management in a Neurocritical Care Unit.

Fever increases mortality and morbidity and length of stay in neurocritically ill patients. Various methods are used in the neuroscience intensive care unit (NSICU) to control fever. Two such methods involve the Arctic Sun hydrogel wraps and the Gaymar cooling wraps. The purpose of our study was to compare these two methods in neurocritical care patients who had temperature >37.5°C for more than three consecutive hours and that was refractory to standard treatments. Data of patients requiring cooling wraps for treatment of hyperthermia at an NSICU at an academic, tertiary referral center were retrospectively reviewed. The average temperature before cooling was 38.5°C ± 0.38°C and 38.4°C ± 0.99°C for the Gaymar and Arctic Sun groups, respectively (p = 0.89). The Gaymar group took on average 16 ± 21.9 hours to reach goal temperature, whereas the Arctic Sun group took 2.22 ± 1.39 hours (p = 0.08). The average time outside of the target temperature was 57.0 ± 58.0 hours in the Gaymar group compared with 13.7 ± 17.1 hours in the Arctic Sun group (p = 0.04). Average duration of using the cooling wraps was similar between the two groups; 81.8% of patients had rebound hyperthermia in the Gaymar group compared with 20% in the Arctic Sun group (p = 0.0089). The Arctic Sun group had a nonsignificant increased incidence of shivering compared with the Gaymar group (40% vs. 18.18%, p = 0.36). We found that Arctic Sun surface cooling device was more efficient in attaining the target temperature, had less incidence of rebound hyperthermia, and was able to maintain normothermia better than Gaymar cooling wraps. The incidence of shivering tended to be more common in the Arctic Sun group.

Clinical Effect of Rebound Hyperthermia After Cooling Postcardiac Arrest: A Retrospective Cohort Study.

Therapeutic hypothermia is used in select patients after out-of-hospital cardiac arrest (OHCA) to improve neurologic outcome. Rebound hyperthermia (RH) is commonly observed post-treatment. Previous studies analyzing the association of RH with clinical outcome have reported conflicting results. The purpose of this study is to examine the impact of RH after completion of therapeutic hypothermia in patients postcardiac arrest. We analyzed a retrospective cohort from our institution. All adults who underwent therapeutic hypothermia post-OHCA were divided into two cohorts depending on the presence/absence of fever (T > 38°C) within 24 hours of completing hypothermia protocol. Clinical outcomes were analyzed at hospital discharge or death. Among 306 patients admitted with OHCA, 117 underwent hypothermia, 97 survived 24 hours postrewarming. Twenty-seven patients (50%) with RH died compared with 20 (47%) without RH (OR, 1.15; 95% CI, 0.52-2.57). Twenty-six patients (67%) with RH had a poor neurologic outcome compared with 27 (63%) without RH (OR 1.19, 95% CI, 0.51-2.74). RH is common after completion of therapeutic hypothermia in comatose patients due to cardiac arrest and is associated with poor neurologic outcomes. We found no significant clinical impact of rebound hypothermia on neurologic outcome or mortality, but our study was underpowered to reveal such impact if it exists.

Therapeutic hypothermia in cardiac arrest survivors: is rebound hyperthermia a significant issue with intravascular cooling?

Therapeutic hypothermia in cardiac arrest survivors: is rebound hyperthermia a significant issue with intravascular cooling?

Cardiovascular and thermoregulatory dysregulation over 24 h following acute heat stress in rats.

The influences of severe heat stroke (HS) on cardiovascular function during recovery are incompletely understood. We hypothesized that HS would elicit a heart rate (HR) increase persisting through 24 h of recovery due to hemodynamic, thermoregulatory, and inflammatory events, necessitating tachycardia to support mean arterial pressure (MAP). Core temperature (Tc), HR, and MAP were measured via radiotelemetry in conscious male Fischer 344 rats (n = 22; 282.4 ± 3.5 g) during exposure to 37°C ambient temperature until a maximum Tc of 42.0°C, and during recovery at 20°C ambient temperature through 24 h. Rats were divided into Mild, Moderate, and Severe groups based on pathophysiology. HS rats exhibited hysteresis relative to Tc with HR higher for a given Tc during recovery compared with heating (P < 0.0001). "Reverse" hysteresis occurred in MAP with pressure during cooling lower than heating per degree Tc (P < 0.0001). Mild HS rats showed tachycardia [P < 0.01 vs. control (Con)] through 8 h of recovery, elevated MAP (P < 0.05 vs. Con) for the initial 5 h of recovery, with sustained hyperthermia (P < 0.05 vs. Con) through 24 h. Moderate HS rats showed significant tachycardia (P < 0.01 vs. Con), normal MAP (P > 0.05 vs. Con), and rebound hyperthermia from 4 to 24 h post-HS (P < 0.05 vs. Con). Severe HS rats showed tachycardia (P < 0.05 vs. Con), hypotension (P < 0.01 vs. Con), and hypothermia for 24 h (P < 0.05 vs. Con). Severe HS rats showed 14- and 12-fold increase in heart and liver inducible nitric oxide synthase expression, respectively. Hypotension and hypothermia in Severe HS rats was consistent with inducible nitric oxide synthase-mediated systemic vasodilation. These findings provide mechanistic insight into hemodynamic and thermoregulatory impairments during 24 h of HS recovery.

Liver transplantation in a child with osteogenesis imperfecta.

We read with great interest the case report by Lee et al. [1], of the anesthetic management of an infant with osteogenesis imperfecta (OI) and progressive familial intrahepatic cholestasis, who was undergoing orthotopic liver transplantation (OLT). This case was indeed challenging, but we would like to add the following comments. First, OI is only weakly associated with malignant hyperthermia, if at all. [2] Cases of intra- or post-operative hyperthermia have indeed been reported, and are thought to be caused by the chronic basal hypermetabolism associated with abnormalities of the collagen structure, thereby resulting in OI. However, a large, recently published case series has demonstrated that the risk of hyperthermia is much lower than was initially assumed. [3] Moreover, over a number of years, thousands of children with OI have received halogenated-based anesthesia with no complications: no case of anesthesia-induced rhabdomyolysis has been observed. Second, the use of propofol-based total intravenous anesthesia, during OLT, is a pharmacologic challenge: initial hepatic function, major fluid shifts and the presence of an anhepatic phase render adaptation of the dosage of propofol to the patient's needs, without measuring its effect on the brain, almost impossible. Only one previous case, of an adult who underwent two OLTs, has been published. [4] In the pediatric case described, liver function was probably initially normal but, as the authors discuss, BIS is unreliable in children of less than 2 years of age: it would therefore be instructive to demonstrate how the infusion rates of propofol and remifentanil were adapted to during surgery, particularly during the anhepatic phase and the initial phase of hepatic reperfusion. The use of a 2% propofol infusion represented a prudent decision to avoid overloading the newly transplanted liver with triglycerides. Third, regarding the prevention of propofol-infusion-syndrome (PRIS), it is recommended that providing > 4 mg/kg/h propofol be avoided, and further that co-administration of sufficient glucose (6 mg/kg/min) might protect against mitochondrial dysfunction [5]: higher doses of propofol (6 mg/kg/h) were apparently used in this case and no data regarding glucose are provided. Using the model of Short, and taking into account both the anhepatic phase and the presence of extrahepatic metabolism, the addition of ketamine or midazolam could have been considered. The early diagnosis of PRIS is difficult during OLT, because the initial biological sign in healthy patients is unexplained lactic acidosis. Fortunately, lactate levels remained low in the presently discussed case. It would be instructive to know the blood lactate threshold used to diagnose PRIS, and the alternative strategy in place if PRIS had occurred. In closing, there are many possible causes of hyperthermia following OLT, including infection, transfusion, rebound hyperthermia following intraoperative hypothermia, iatrogenesis, and malignant hyperthermia (MH). Fever represents a late sign of MH: other indicators are generally present at the time of initial occurrence, such as hypercarbia, hyperkalemia, dysrhythmias, and dark urine (myoglobinuria). In this context, the blood gases observed upon arrival at the PICU were more concerning, in terms of indicating a possible MH crisis, compared with those measured at the time of fever. The authors should be congratulated for drawing attention to the possible pharmacologic effects of non-anesthetic drugs (namely to those contained in the liver conservation solution) administered during an OLT.

Impact of case volume on outcome and performance of targeted temperature management in out-of-hospital cardiac arrest survivors

PurposeThis study aimed to determine the effect of case volume on targeted temperature management (TTM) performance, incidence of adverse events, and neurologic outcome in comatose out-of-hospital cardiac arrest (OHCA) survivors treated with TTM. MethodsWe used a Web-based, multicenter registry (Korean Hypothermia Network registry), to which 24 hospitals throughout the Republic of Korea participated to study adult (≥18 years) comatose out-of-hospital cardiac arrest patients treated with TTM between 2007 and 2012. The primary outcome was neurologic outcome at hospital discharge. The secondary outcomes were inhospital mortality, TTM performance, and adverse events. We extracted propensity-matched cohorts to control for bias. Multivariate logistic regression analysis was performed to assess independent risk factors for neurologic outcome. ResultsA total of 901 patients were included in this study; 544 (60.4%) survived to hospital discharge, and 248 (27.5%) were discharged with good neurologic outcome. The high-volume hospitals initiated TTM significantly earlier and had lower rates of hyperglycemia, bleeding, hypotension, and rebound hyperthermia. However, neurologic outcome and inhospital mortality were comparable between high-volume (27.7% and 44.6%, respectively) and low-volume hospitals (21.1% and 40.5%) in the propensity-matched cohorts. The adjusted odds ratio for the high-volume hospitals compared with low-volume hospitals was 1.506 (95% confidence interval, 0.875-2.592) for poor neurologic outcome. ConclusionsHigher TTM case volume was significantly associated with early initiation of TTM and lower incidence of adverse events. However, case volume had no association with neurologic outcome and inhospital mortality.

Cardiovascular and thermoregulatory biomarkers of heat stroke severity in a conscious rat model.

Multiorgan failure is a catastrophic consequence of heat stroke (HS) and considered the underlying etiology of mortality. Identifying novel biomarkers capable of predicting the extent of HS-induced organ damage will enhance point-of-care triage and treatment. Conscious male F344 rats (n = 32) were radiotelemetered for continuous core temperature (Tc), heart rate, and arterial pressure measurement. Twenty-two animals were exposed to ambient temperature of 37°C to a maximum Tc of 41.9 ± 0.1°C. Rats were euthanized at 24 h of recovery for analysis of plasma biomarkers [cardiac troponin I (cTnI), blood urea nitrogen (BUN), alanine aminotransferase (ALT), albumin, glucose] and histology. Tc profiles observed during recovery stratified HS severity into Mild, Moderate, and Severe. Eleven (50%) animals exhibited an acute compensatory hemodynamic response to heat exposure and a monophasic Tc profile consisting of sustained hyperthermia (∼1°C). Five (23%) rats displayed hemodynamic challenge and a biphasic Tc profile with rapid return to baseline followed by rebound hyperthermia. All biomarkers were significantly altered from control values (P < 0.05). Four (18%) animals exhibited significant hemodynamic compromise during heat and a triphasic profile characterized by rapid cooling to baseline Tc, rebound hyperthermia, and subsequent hypothermia (∼35°C) through 24 h. cTnI showed a 40-fold increase over CON (P < 0.001) and correlated with BUN (r = 0.912) consistent with cardiorenal failure. Hypoglycemia correlated with ALT (r = 0.824) suggestive of liver dysfunction. Histology demonstrated myocardial infarction, renal tubular necrosis, and acute liver necrosis. Two (9%) animals succumbed during HS recovery. This study identified novel biomarkers that predict HS severity and organ damage during acute recovery that could provide clinical significance for identifying key biomarkers of HS pathogenesis.

Impact of case volume on performance of targeted temperature management, incidence of adverse events, and neurologic outcome in comatose out-of-hospital cardiac arrest survivors treated with targeted temperature management: A propensity score matching analysis

s / Resuscitation 85S (2014) S15–S121 S97 off number between low volume and high volume hospital was 15.5 per year. The high volume hospitals started TTM significantly earlier following ROSC and had lower rate of hyperglycaemia, bleeding, hypotension, and rebound hyperthermia. However, good neurologic outcome and in-hospital mortality were comparable between high volume (27.7% and 44.6%, respectively) and low volume hospitals (21.1% and 40.5%) in the propensity matched cohort. The adjusted odds ratio in the high volume hospitals compared to lowvolumehospitalswere1.506 (95% confidence interval: 0.875–2.592) for poor neurologic outcome. Conclusions: The higher case volume of TTM was significantly associated with early initiation of TTM and lower incidence of adverse events. However, the case volume had no association with the neurologic outcome and in-hospital mortality. http://dx.doi.org/10.1016/j.resuscitation.2014.03.239

Incidence of rebound hyperthermia and inflammatory characteristics in cooled post-cardiac arrest patients

Incidence of rebound hyperthermia and inflammatory characteristics in cooled post-cardiac arrest patients

Assessment of risk factors for post-rewarming “rebound hyperthermia” in cardiac arrest patients undergoing therapeutic hypothermia

IntroductionThe outcomes associated with therapeutic hypothermia (TH) after cardiac arrest, while overwhelmingly positive, may be associated with adverse events. The incidence of post-rewarming rebound hyperthermia (RH) has been relatively unstudied and may worsen survival and neurologic outcome. The purpose of this study was to determine the incidence and risk factors associated with RH as well as its relationship to mortality, neurologic morbidity, and hospital length of stay (LOS). MethodsA retrospective, observational study was performed of adult patients who underwent therapeutic hypothermia after an out-of-hospital cardiac arrest. Data describing 17 potential risk factors for RH were collected. The primary outcome was the incidence of RH while the secondary outcomes were mortality, discharge neurologic status, and LOS. Results141 patients were included. All 17 risk factors for RH were analyzed and no potential risk factors were found to be significant at a univariate level. 40.4% of patients without RH experienced any cause of death during the initial hospitalization compared to 64.3% patients who experienced RH (OR: 2.66; 95% CI: 1.26–5.61; p=0.011). The presence of RH is not associated with an increase in LOS (10.67 days vs. 9.45 days; absolute risk increase=−1.21 days, 95% CI: −1.84 to 4.27; p=0.434). RH is associated with increased neurologic morbidity (p=0.011). ConclusionsWhile no potential risk factors for RH were identified, RH is a marker for increased mortality and worsened neurologic morbidity in cardiac arrest patients who have underwent TH.

Correspondence Regarding: Cooling Practices and Outcome following Therapeutic Hypothermia for Cardiac Arrest

1We conducted a similar review from our single centre district general hospital (DGH) intensive care unit (ICU) for a shorter period of one year. We identified patients retrospectively using ICNARC data and collected 31 items of data per patient from case notes. Our dataset included basic demographics, cardiac arrest details, TH details and outcome up to hospital discharge. The main purpose of our review was to ascertain if our recently introduced trust TH guideline was being appropriately used and efficiently applied. Our numbers (n=21) are interestingly large for a single centre compared with Nichani’s review (102 patients for 9 centres over 15 months). With regard to the application of TH, our trust TH protocol had strict exclusion criteria (no specific contraindications were described in the Nichani review). However, two patients in our review who did not receive TH were inappropriately excluded. The median time to initiate cooling was over 30 minutes faster in our review (95 minutes compared with 126 minutes). Our trust protocol specified that the target temperature of 32-34°C should be reached within two hours of return of spontaneous circulation (ROSC) (no time target was specified in the Nichani review). However, none of the patients in our review reached the target temperature within two hours. In the Nichani review, the median time to 32-34°C was over seven hours (425 minutes). We noted that Nichani was unable to show statistical difference between differing cooling methods. Our review, although not tested to statistical significance, suggested a trend towards better achievement of temperature targets with cold IV fluid infusion. We did not measure total duration of cooling and time to rewarming, but we did measure compliance with the temperature- and time-specific targets for maintenance and rewarming in our protocol. Our results were mixed, showing that 42% of our patients achieved compliance with maintaining temperatures, but only 16% achieved compliance with rewarming temperatures. With regard to outcome for TH, survival to ICU discharge was worse in our unit, at 37%, compared with 45% in the Nichani review. We were also unable to show an improvement in these figures by looking at only VF/VT arrests, with survival of 36% compared with 53% reported by Nichani et al. The patients in our review might have been expected to have more favourable outcomes, as 76% of our patients presented in VF (compared with 68% in the review). However, other factors may have contributed to poorer outcomes – only 57% of our patients received immediate bystander CPR, compared with 80% in the Nichani review; the median age of our patients was 68 years compared to 61 years in the Nichani review, and the median duration of arrest was 23 minutes in our review, compared with 20 minutes in the Nichani review. After completing our review, and in the light of our unit’s level of compliance with regard to achieving the temperatures specified in the TH protocol and poor outcomes in comparison with the Nichani and other reviews, we are embarking upon an educational programme and seeking to purchase a gel pad cooling device to ensure that TH is achieved quickly, adequately maintained and patients rewarmed without rebound hyperthermia. References

22 Incidence and Risk Factors of Post-Rewarming “Rebound Hyperthermia” in Cardiac Arrest Patients Undergoing Therapeutic Hypothermia

22 Incidence and Risk Factors of Post-Rewarming “Rebound Hyperthermia” in Cardiac Arrest Patients Undergoing Therapeutic Hypothermia