Impact of time to cooling initiation and time to target temperature in patients treated with hypothermia after cardiac arrest

Non-linear association between the time required to reaching temperature targets and the neurological outcome in patients undergoing targeted temperature management after out-of-hospital cardiac arrest: Observational multicentre cohort study

Purpose

We evaluated associations between outcomes and time to achieving temperature targets during targeted temperature management of out-of-hospital cardiac arrest.

Methods

Using Comprehensive Registry of Intensive Care for out-of-hospital cardiac arrest Survival (CRITICAL) study, we enrolled all patients transported to participating hospitals from 1 July 2012 through 31 December 2017 aged ≥ 18 years with out-of-hospital cardiac arrest of cardiac aetiology and who received targeted temperature management in Osaka, Japan. Primary outcome was Cerebral Performance Category scale of 1 or 2 one month after cardiac arrest, designated as "one-month favourable neurological outcome". Non-linear multivariable logistic regression analyses assessed the primary outcome based on time to reaching temperature targets. In patients subdivided into quintiles based on time to achieving temperature targets, multivariable logistic regression calculated adjusted odds ratios and 95% confidence intervals.

Results

We analysed 473 patients. In non-linear multivariable logistic regression analysis, p value for non-linearity was < 0.01. In the first quintile (< 26.7 minutes), second quintile (26.8-89.9 minutes), third quintile (90.0-175.1 minutes), fourth quintile (175.2-352.1 minutes), and fifth quintile (≥ 352.2 minutes), one-month favourable neurological outcome was 32.6% (31/95), 40.0% (36/90), 53.5% (53/99), 57.4% (54/94), and 37.9% (36/95), respectively. Adjusted odds ratios with 95% confidence intervals for one-month favourable neurological outcome in the first, second, third, and fifth quintiles compared with the fourth quintile were 0.38 (0.20 to 0.72), 0.43 (0.23 to 0.81), 0.77 (0.41 to 1.44), and 0.46 (0.25 to 0.87), respectively.

Conclusion

Non-linear multivariable logistic regression analysis could clearly describe the association between neurological outcome in patients with out-of-hospital cardiac arrest and the time from the introduction of targeted temperature management to reaching the temperature targets.

COMPARISON BETWEEN ACTIVE ABDOMINAL COMPRESSION-DECOMPRESSION CARDIOPULMONARY RESUSCITATION AND STANDARD CARDIOPULMONARY RESUSCITATION IN ASPHYCTIC CARDIAC ARREST RATS WITH MULTIPLE RIB FRACTURES

ABSTRACT

Background: Active abdominal compression-decompression cardiopulmonary resuscitation (AACD-CPR) is potentially more effective for cardiac arrest (CA) with multiple rib fractures. However, its effect on survival rates and neurological outcomes remains unknown. This study aimed to assess if AACD-CPR improves survival rates and neurological outcomes in a rat model of asphyctic CA with multiple rib fractures. Methods: Adult male Sprague-Dawley rats were randomized into three groups-AACD group (n = 15), standard cardiopulmonary resuscitation (STD-CPR) group (n = 15), and sham group (n = 10)-after bilateral rib fractures were surgically created and endotracheal intubation was performed. AACD-CPR and STD-CPR groups underwent 8 min of asphyxia followed by different CPR techniques. The sham group had venous catheterization only. Physiological variables and arterial blood gases were recorded at baseline and during a 4-h monitoring period. Neurological deficit scores (NDSs) and cumulative survival rates were assessed at 24, 48, and 72 h. NDS, serum biomarkers, and hippocampal neuron analysis were used to evaluate neurological outcomes. Results: No statistical differences were observed in the return of spontaneous circulation (ROSC), 24-, 48-, and 72-h survival rates between the AACD-CPR and STD-CPR groups. AACD-CPR rats had lower serum levels of neuron-specific enolase and S100B at 72 h post-ROSC, and higher NDS at 72 h post-ROSC compared with STD-CPR animals. Cellular morphology analysis, hematoxylin and eosin staining, and TUNEL/DAPI assays showed more viable neurons and fewer apoptotic neurons in the AACD-CPR group than in the STD-CPR group. Conclusions: AACD-CPR can achieve similar survival rates and better neurological outcome after asphyxial CA in rats with multiple rib fractures when compared with STD-CPR.

Targeted Temperature Management for Patients with Acute Ischemic Stroke: A Literature Review

Despite significant advances in medical imaging, thrombolytic therapy, and mechanical thrombectomy, acute ischemic strokes (AIS) remain a major cause of mortality and morbidity globally. Targeted temperature management (TTM) has emerged as a potential therapeutic intervention, aiming to mitigate neuronal damage and improve outcomes. This literature review examines the efficacy and challenges of TTM in the context of an AIS. A comprehensive literature search was conducted using databases such as PubMed, Cochrane, Web of Science, and Google Scholar. Studies were selected based on relevance and quality. We identified key factors influencing the effectiveness of TTM such as its timing, depth and duration, and method of application. The review also highlighted challenges associated with TTM, including increased pneumonia rates. The target temperature range was typically between 32 and 36 °C, with the duration of cooling from 24 to 72 h. Early initiation of TTM was associated with better outcomes, with optimal results observed when TTM was started within the first 6 h post-stroke. Emerging evidence indicates that TTM shows considerable potential as an adjunctive treatment for AIS when implemented promptly and with precision, thereby potentially mitigating neuronal damage and enhancing overall patient outcomes. However, its application is complex and requires the careful consideration of various factors.

A Commentary on the Effect of Targeted Temperature Management in Patients Resuscitated from Cardiac Arrest

The members of the International Liaison Committee on Resuscitation (ILCOR) Advanced Life Support Task Force have written a comprehensive summary of trials of the effectiveness of induced hypothermia (IH) or targeted temperature management (TTM) in comatose patients after cardiac arrest (CA). However, in-depth analysis of these studies is incomplete, especially since there was no significant difference in primary outcome between hypothermia versus normothermia in the recently reported TTM2 trial. We critically appraise trials of IH/TTM versus normothermia to characterize reasons for the lack of treatment effect, based on a previously published framework for what to consider when the primary outcome fails. We found a strong biologic rationale and external clinical evidence that IH treatment is beneficial. Recent TTM trials mainly included unselected patients with a high rate of bystander cardiopulmonary resuscitation. The treatment was not applied as intended, which led to a large delay in achievement of target temperature. While receiving intensive care, sedative drugs were likely used that might have led to increased neurologic damage as were antiplatelet drugs that could be associated with increased acute stent thrombosis in hypothermic patients. It is reasonable to still use or evaluate IH treatment in patients who are comatose after CA as there are multiple plausible reasons why IH compared to normothermia did not significantly improve neurologic outcome in the TTM trials.

Optimal Timing of Targeted Temperature Management for Post-Cardiac Arrest Syndrome: Is Sooner Better?

Targeted temperature management (TTM) is often considered to improve post-cardiac arrest patients’ outcomes. However, the optimal timing to initiate cooling remained uncertain. This retrospective analysis enrolled all non-traumatic post-cardiac arrest adult patients with either out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA) who received TTM from July 2015 to July 2021 at our hospital. The values of time delay before TTM and time to target temperature were divided into three periods according to optimal cut-off values identified using receiver operating characteristic curve analysis. A total of 177 patients were enrolled. A shorter time delay before TTM (pre-induction time) was associated with a lower survival chance at 28 days (32.00% vs. 54.00%, p = 0.0279). Patients with a longer cooling induction time (>440 minis) had better neurological outcomes (1.58% vs. 1.05%; p = 0.001) and survival at 28 days (58.06% vs. 29.25%; p = 0.006). After COX regression analysis, the influence of pre-induction time on survival became insignificant, but patients who cooled slowest still had a better chance of survival at 28 days. In conclusion, a shorter delay before TTM was not associated with better clinical outcomes. However, patients who took longer to reach the target temperature had better hospital survival and neurological outcomes than those who were cooled more rapidly. A further prospective study was warranted to evaluate the appropriate time window of TTM.

Artificial neural network-boosted Cardiac Arrest Survival Post-Resuscitation In-hospital (CASPRI) score accurately predicts outcome in cardiac arrest patients treated with targeted temperature management

Existing prognostic models to predict the neurological recovery in patients with cardiac arrest receiving targeted temperature management (TTM) either exhibit moderate accuracy or are too complicated for clinical application. This necessitates the development of a simple and generalizable prediction model to inform clinical decision-making for patients receiving TTM. The present study explores the predictive validity of the Cardiac Arrest Survival Post-resuscitation In-hospital (CASPRI) score in cardiac arrest patients receiving TTM, regardless of cardiac event location, and uses artificial neural network (ANN) algorithms to boost the prediction performance. This retrospective observational study evaluated the prognostic relevance of the CASPRI score and applied ANN to develop outcome prediction models in a cohort of 570 patients with cardiac arrest and treated with TTM between 2014 and 2019 in a nationwide multicenter registry in Taiwan. In univariate logistic regression analysis, the CASPRI score was significantly associated with neurological outcome, with the area under the receiver operating characteristics curve (AUC) of 0.811. The generated ANN model, based on 10 items of the CASPRI score, achieved a training AUC of 0.976 and validation AUC of 0.921, with the accuracy, precision, sensitivity, and specificity of 89.2%, 91.6%, 87.6%, and 91.2%, respectively, for the validation set. CASPRI score has prognostic relevance in patients who received TTM after cardiac arrest. The generated ANN-boosted, CASPRI-based model exhibited good performance for predicting TTM neurological outcome, thus, we propose its clinical application to improve outcome prediction, facilitate decision-making, and formulate individualized therapeutic plans for patients receiving TTM.

Ultrafast Hypothermia Selectively Mitigates the Early Humoral Response After Cardiac Arrest

Background

Total liquid ventilation (TLV) has been shown to prevent neurological damage though ultrafast cooling in animal models of cardiac arrest. We investigated whether its neuroprotective effect could be explained by mitigation of early inflammatory events.

Methods and Results

Rabbits were submitted to 10 minutes of ventricular fibrillation. After resuscitation, they underwent normothermic follow‐up (control) or ultrafast cooling by TLV and hypothermia maintenance for 3 hours (TLV). Immune response, survival, and neurological dysfunction were assessed for 3 days. TLV improved neurological recovery and reduced cerebral lesions and leukocyte infiltration as compared with control (eg, neurological dysfunction score=34±6 versus 66±6% at day 1, respectively). TLV also significantly reduced interleukin‐6 blood levels during the hypothermic episode (298±303 versus 991±471 pg/mL in TLV versus control at 3 hours after resuscitation, respectively), but not after rewarming (752±563 versus 741±219 pg/mL in TLV versus control at 6 hours after resuscitation, respectively). In vitro assays confirmed the high temperature sensitivity of interleukin‐6 secretion. Conversely, TLV did not modify circulating high‐mobility group box 1 levels or immune cell recruitment into the peripheral circulation. The link between interleukin‐6 early transcripts (<8 hours) and neurological outcome in a subpopulation of the previously described Epo‐ACR‐02 (High Dose of Erythropoietin Analogue After Cardiac Arrest) trial confirmed the importance of this cytokine at the early stages as compared with delayed stages (>8 hours).

Conclusions

The neuroprotective effect of hypothermic TLV was associated with a mitigation of humoral interleukin‐6 response. A temperature‐dependent attenuation of immune cell reactivity during the early phase of the post–cardiac arrest syndrome could explain the potent effect of rapid hypothermia.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT00999583.

Door-to-Targeted Temperature Management Initiation Time and Outcomes in Out-of-Hospital Cardiac Arrest: Insights From the Continuous Chest Compressions Trial

Background

Targeted temperature management (TTM) is a recommended treatment modality to improve neurological outcomes in patients with out‐of‐hospital cardiac arrest. The impact of the duration from hospital admission to TTM initiation (door‐to‐TTM; DTT) on clinical outcomes has not been well elucidated. We hypothesized that shorter DTT initiation intervals would be associated with improved survival with favorable neurological outcome.

Methods and Results

We performed a post hoc analysis of nontraumatic paramedic‐treated out‐of‐hospital cardiac arrests. The primary outcome was favorable neurological status at hospital discharge, with a secondary outcome of survival to discharge. We fit a logistic regression analysis to determine the association of early compared with delayed DTT, dichotomized by the median DTT duration, and outcomes. Of 3805 patients enrolled in the CCC (Continuous Chest Compressions) Trial in British Columbia, 570 were included in this analysis. There was substantial variation in DTT among patients receiving TTM. The median DTT duration was 122 minutes (interquartile range 35‐218). Favorable neurological outcomes in the early and delayed DTT groups were 48% and 38%, respectively. Compared with delayed DTT (interquartile range 167‐319 minutes), early DTT (interquartile range 20‐81 minutes) was associated with survival (adjusted odds ratio 1.56, 95% CI 1.02‐2.38) but not with favorable neurological outcomes (adjusted odds ratio 1.45, 95% CI, 0.94‐2.22) at hospital discharge.

Conclusions

There was wide variability in the initiation of TTM among comatose out‐of‐hospital cardiac arrest survivors. Initiation of TTM within 122 minutes of hospital admission was associated with improved survival. These results support in‐hospital efforts to achieve early DTT among out‐of‐hospital cardiac arrest patients admitted to the hospital.

See Editorial Schenone and Menon

Systematic review and meta-analysis of intravascular temperature management vs. surface cooling in comatose patients resuscitated from cardiac arrest

OBJECTIVE

To systematically review the effectiveness and safety of intravascular temperature management (IVTM) vs. surface cooling methods (SCM) for induced hypothermia (IH).

METHODS

Systematic review and meta-analysis. English-language PubMed, Embase and the Cochrane Database of Systematic Reviews were searched on May 27, 2019. The quality of included observational studies was graded using the Newcastle-Ottawa Quality Assessment tool. The quality of included randomized trials was evaluated using the Cochrane Collaboration's risk of bias tool. Random effects modeling was used to calculate risk differences for each outcome. Statistical heterogeneity and publication bias were assessed using standard methods.

ELIGIBILITY

Observational or randomized studies comparing survival and/or neurologic outcomes in adults aged 18 years or greater resuscitated from out-of-hospital cardiac arrest receiving IH via IVTM vs. SCM were eligible for inclusion.

RESULTS

In total, 12 studies met inclusion criteria. These enrolled 1573 patients who received IVTM; and 4008 who received SCM. Survival was 55.0% in the IVTM group and 51.2% in the SCM group [pooled risk difference 2% (95% CI -1%, 5%)]. Good neurological outcome was achieved in 40.9% in the IVTM and 29.5% in the surface group [pooled risk difference 5% (95% CI 2%, 8%)]. There was a 6% (95% CI 11%, 2%) lower risk of arrhythmia with use of IVTM and 15% (95% CI 22%, 7%) decreased risk of overcooling with use of IVTM vs. SCM. There was no significant difference in other evaluated adverse events between groups.

CONCLUSIONS

IVTM was associated with improved neurological outcomes vs. SCM among survivors resuscitated following cardiac arrest. These results may have implications for care of patients in the emergency department and intensive care settings after resuscitation from cardiac arrest.

Increased Heat Generation in Postcardiac Arrest Patients During Targeted Temperature Management Is Associated With Better Outcomes

OBJECTIVES

Assess if amount of heat generated by postcardiac arrest patients to reach target temperature (Ttarget) during targeted temperature management is associated with outcomes by serving as a proxy for thermoregulatory ability, and whether it modifies the relationship between time to Ttarget and outcomes.

DESIGN

Retrospective cohort study.

SETTING

Urban tertiary-care hospital.

PATIENTS

Successfully resuscitated targeted temperature management-treated adult postarrest patients between 2008 and 2015 with serial temperature data and Ttarget less than or equal to 34°C.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Time to Ttarget was defined as time from targeted temperature management initiation to first recorded patient temperature less than or equal to 34°C. Patient heat generation ("heat units") was calculated as inverse of average water temperature × hours between initiation and Ttarget × 100. Primary outcome was neurologic status measured by Cerebral Performance Category score; secondary outcome was survival, both at hospital discharge. Univariate analyses were performed using Wilcoxon rank-sum tests; multivariate analyses used logistic regression. Of 203 patients included, those with Cerebral Performance Category score 3-5 generated less heat before reaching Ttarget (median, 8.1 heat units [interquartile range, 3.6-21.6 heat units] vs median, 20.0 heat units [interquartile range, 9.0-33.5 heat units]; p = 0.001) and reached Ttarget quicker (median, 2.3 hr [interquartile range, 1.5-4.0 hr] vs median, 3.6 hr [interquartile range, 2.0-5.0 hr]; p = 0.01) than patients with Cerebral Performance Category score 1-2. Nonsurvivors generated less heat than survivors (median, 8.1 heat units [interquartile range, 3.6-20.8 heat units] vs median, 19.0 heat units [interquartile range, 6.5-33.5 heat units]; p = 0.001) and reached Ttarget quicker (median, 2.2 hr [interquartile range, 1.5-3.8 hr] vs median, 3.6 hr [interquartile range, 2.0-5.0 hr]; p = 0.01). Controlling for average water temperature between initiation and Ttarget, the relationship between outcomes and time to Ttarget was no longer significant. Controlling for location, witnessed arrest, age, initial rhythm, and neuromuscular blockade use, increased heat generation was associated with better neurologic (adjusted odds ratio, 1.01 [95% CI, 1.00-1.03]; p = 0.039) and survival (adjusted odds ratio, 1.01 [95% CI, 1.00-1.03]; p = 0.045) outcomes.

CONCLUSIONS

Increased heat generation during targeted temperature management initiation is associated with better outcomes at hospital discharge and may affect the relationship between time to Ttarget and outcomes.

Development and External Validation of an Early Prognostic Model for Survivors of Out-of-hospital Cardiac Arrest

INTRODUCTION AND OBJECTIVES

Despite therapeutic hypothermia, unconscious survivors of out-of-hospital cardiac arrest have a high risk of death or poor neurologic function. Our objective was to assess the usefulness of the variables obtained in the early moments after resuscitation in the prediction of 6-month prognosis.

METHODS

A multicenter study was performed in 3 intensive cardiac care units. The analysis was done in 153 consecutive survivors of out-of-hospital cardiac arrest who underwent targeted temperature management between January 2007 and July 2015. Significant neurological sequelae at 6 months were considered to be present in patients with Cerebral Performance Categories Scale > 2. An external validation was performed with data from 91 patients admitted to a third hospital in the same time interval.

RESULTS

Among the 244 analyzed patients (median age, 60 years; 77.1% male; 50.0% in the context of acute myocardial ischemia), 107 patients (43.8%) survived with good neurological status at 6 months. The prediction model included 5 variables (Shockable rhythm, Age, Lactate levels, Time Elapsed to return of spontaneous circulation, and Diabetes - SALTED) and provided an area under the curve of 0.90 (95%CI, 0.85-0.95). When external validation was performed, the predictive model showed a sensitivity of 73.5%, specificity of 78.6%, and area under the curve of 0.82 (95%CI, 0.73-0.91).

CONCLUSIONS

A predictive model that includes 5 clinical and easily accessible variables at admission can help to predict the probability of survival without major neurological damage following out-of-hospital cardiac arrest.

Ventilator Management and Respiratory Care After Cardiac Arrest: Oxygenation, Ventilation, Infection, and Injury

Return of spontaneous circulation after cardiac arrest results in a systemic inflammatory state called the post-cardiac arrest syndrome, which is characterized by oxidative stress, coagulopathy, neuronal injury, and organ dysfunction. Perturbations in oxygenation and ventilation may exacerbate secondary injury after cardiac arrest and have been shown to be associated with poor outcome. Further, patients who experience cardiac arrest are at risk for a number of other pulmonary complications. Up to 70% of patients experience early infection after cardiac arrest, and the respiratory tract is the most common source. Vigilance for early-onset pneumonia, as well as aggressive diagnosis and early antimicrobial agent administration are important components of critical care in this population. Patients who experience cardiac arrest are at risk for the development of ARDS. Risk factors include aspiration, pulmonary contusions (from chest compressions), systemic inflammation, and reperfusion injury. Early evidence suggests that they may benefit from ventilation with low tidal volumes. Meticulous attention to mechanical ventilation, early assessment and optimization of respiratory gas exchange, and therapies targeted at potential pulmonary complications may improve outcomes after cardiac arrest.

Initial arterial carbon dioxide tension is associated with neurological outcome after resuscitation from cardiac arrest

STUDY OBJECTIVES

To determine the relationships between partial pressure of arterial carbon dioxide (PaCO₂), prescribed minute ventilation (MV), and neurologic outcome in patients resuscitated from cardiac arrest.

METHODS

This was a retrospective cohort study utilizing a multicenter database of adult patients with return of spontaneous circulation (ROSC) after cardiac arrest. The primary outcome was neurologic status at hospital discharge, defined by Cerebral Performance Category (CPC) score: CPC 1-2 was favorable, CPC 3-5 was poor. We compared rates of initial normocarbia (PaCO₂ 31-49mmHg) and mean sequential PaCO₂ measurements obtained over the first 24h. We also assessed the influence of MV on the PaCO₂ at initial, 6, 12, 18, and 24h after cardiac arrest using univariate linear regression.

RESULTS

One hundred and fourteen patients from 3 institutions met inclusion criteria. Overall, 46/114 (40.4%, 95% CI: 31.4-49.4%) patients survived to hospital discharge, and 33/114 (28.9%, 20.6-37.2%) had CPC 1-2 at the time of discharge. A total of 38.9% (95% CI: 29.9-47.9%) of patients had initial normocarbia; 43.2% (28.6-57.8%) of these patients were discharged with CPC 1-2, compared with 20.3% (10.8-29.8%) of dyscarbic patients. By 6h, neurologic outcomes were not significantly associated with PaCO₂. Prescribed MV was not associated with PaCO₂ at any time point with the exception of a weak correlation at hour 18.

CONCLUSION

Initial normocarbia was associated with favorable neurological outcome in patients resuscitated from cardiac arrest. This relationship was not seen at subsequent time points. There was no significant association between prescribed MV and PaCO₂ or neurologic outcome.

Time to Cooling Is Associated with Resuscitation Outcomes

Our purpose was to analyze evidence related to timing of cooling from studies of targeted temperature management (TTM) after return of spontaneous circulation (ROSC) after cardiac arrest and to recommend directions for future therapy optimization. We conducted a preliminary review of studies of both animals and patients treated with post-ROSC TTM and hypothesized that a more rapid cooling strategy in the absence of volume-adding cold infusions would provide improved outcomes in comparison with slower cooling. We defined rapid cooling as the achievement of 34°C within 3.5 hours of ROSC without the use of volume-adding cold infusions, with a ≥3.0°C/hour rate of cooling. Using the PubMed database and a previously published systematic review, we identified clinical studies published from 2002 through 2014 related to TTM. Analysis included studies with time from collapse to ROSC of 20–30 minutes, reporting of time from ROSC to target temperature and rate of patients in ventricular tachycardia or ventricular fibrillation, and hypothermia maintained for 20–24 hours. The use of cardiopulmonary bypass as a cooling method was an exclusion criterion for this analysis. We compared all rapid cooling studies with all slower cooling studies of ≥100 patients. Eleven studies were initially identified for analysis, comprising 4091 patients. Two additional studies totaling 609 patients were added based on availability of unpublished data, bringing the total to 13 studies of 4700 patients. Outcomes for patients, dichotomized into faster and slower cooling approaches, were determined using weighted linear regression using IBM SPSS Statistics software. Rapid cooling without volume-adding cold infusions yielded a higher rate of good neurological recovery than slower cooling methods. Attainment of a temperature below 34°C within 3.5 hours of ROSC and using a cooling rate of more than 3°C/hour appear to be beneficial.

Early Prognosticators for Induction of Therapeutic Hypothermia Following Cardiac Arrest

The American Heart Association recommends therapeutic hypothermia for comatose patients with return of spontaneous circulation after out-of-hospital ventricular fibrillation cardiac arrest. While there is a growing body of evidence for the general efficacy of therapeutic hypothermia, the individualized benefit of therapy is not currently predictable. Ninety-one consecutive patients, from April 2011 to July 2014, were treated at the University of Kentucky Medical Center with the therapeutic hypothermia protocol. Medical records were reviewed retrospectively. Data, such as preexisting comorbidities, cardiac arrest characteristics, and hospital course, were used to compose a multivariate logistic regression with mortality serving as the primary endpoint. The overall in-hospital mortality was 64% (n = 58) in this group. The arrest was considered cardiac etiology in 84% (n = 76) of patients, of which 49% (n = 45) were classed as ventricular fibrillation and 9% (n = 8) as ventricular tachycardia. The presence of a shockable rhythm, as well as shorter duration of cardiac arrest, was associated with increased survival, whereas time to target temperature was not. The presence of a preexisting neurologic disease was associated with a 10-fold increase in estimated odds of mortality. Age, serum lactate, ionized calcium, arterial pH, estimated glomerular filtration rate, and APACHE score were all predictors of mortality. Cardiac arrest is a devastating condition with a high mortality rate. Given the limited resources of the resuscitation community, the ability to predict survivors based on routinely obtained measures upon admission would be of tremendous value. In this study, we show a series of admission parameters that demonstrate predictive ability in identifying patients more likely to survive with therapeutic hypothermia.

Endovascular Cooling Method for Hypothermia in Injured Swine

We evaluated an endovascular cooling method to modulate core temperature in trauma swine models with and without fluid support. Anesthetized swine (N = 80) were uninjured (SHAM) or injured through a bone fracture plus soft tissue injury or an uncontrolled hemorrhage and then subdivided to target body temperatures of 38°C (normothermia) or 33°C (hypothermia) by using a Thermogard endovascular cooling device (Zoll Medical). Temperature regulation began simultaneously at onset of injury (T0). Body temperatures were recorded from a rectal probe (Rec Temp) and from a central pulmonary artery catheter (PA Temp). At T15, swine received 500 mL IV Hextend over 30 minutes or no treatment (NONE) with continued monitoring until 3 hours from injury. Hypothermia was attained in 105 ± 39 minutes, at a cooling rate of -0.061°C ± 0.007°C/min for NONE injury groups. Postinjury Hextend administration resulted in faster cooling (-0.080°C ± 0.006°C/min); target temperature was reached in 83 ± 11 minutes (p < 0.05). During active cooling, body temperature measured by the PA Temp was significantly cooler than the Rec Temp due to the probe's closer proximity to the blood-cooling catheter balloons (p < 0.05). This difference was smaller in SHAM and fluid-supported injury groups (1.1°C ± 0.4°C) versus injured NONE groups (2.1°C ± 0.3°C). Target temperatures were correctly maintained thereafter in all groups. In normothermia groups, there was a small initial transient overshoot to maintain 38°C. Despite the noticeable difference between PA Temp and Rec Temp until target temperature was attained, this endovascular method can safely induce moderate hypothermia in anesthetized swine. However, likely due to their compromised hemodynamic state, cooling in hypovolemic and/or injured patients will be different from those without injury or those that also received fluids.

Severe acidemia on arrival not predictive of neurologic outcomes in post-cardiac arrest patients

PURPOSE

This study aimed to determine whether severe acidemia (pH <7.2) on arrival at the emergency department (ED) is a predictive factor for neurologic outcomes of post-cardiac arrest patients treated with targeted temperature management (TTM).

MATERIALS AND METHODS

Data in the National Disaster Medical Center, a tertiary care hospital, were used to perform a case-control study on post-cardiac arrest patients treated with TTM from January 2013 to April 2015. The case group comprised patients with good neurologic outcomes (cerebral performance categories 1 and 2), whereas the control group comprised patients with poor neurologic outcomes (cerebral performance categories 3-5). Exposure was defined as arterial pH less than 7.2 on arrival at the ED.

RESULTS

We identified 32 patients matching our criteria, of which 13 had good outcomes and 19 poor outcomes. Arterial pH on arrival was not significantly associated with neurologic outcomes (P = .47; odds ratio, 0.5; 95% confidence interval, 0.09-2.61). In 24 patients with cardiogenic causes of cardiac arrest, pH on arrival was not significantly associated with neurologic outcomes (P = .68; odds ratio, 0.5; 95% confidence interval, 0.09-2.73) after matched-pair analysis by age, sex, and presence of light reflex.

CONCLUSION

Severe acidemia on arrival at the ED is not a significant predictive factor for neurologic outcomes in post-cardiac arrest patients treated with TTM, particularly in patients with cardiogenic causes of cardiac arrest. These results suggest that treatment should not be withheld in post-cardiac arrest patients with severe acidemia.