Severity-Driven Trends in Mortality in a Large Regionalized Critical Care Transport Service.

OBJECTIVE: The epidemiology accompanying helicopter emergency medical services (HEMS) transport has evolved as agencies have matured and become integrated into regionalized health systems, as evidenced primarily by nationwide systems in Europe. System-level congruence between Europe and the United States, where HEMS is geographically fragmentary, is unclear. In this study, we provide a temporal, epidemiologic characterization of the largest standardized private, nonprofit HEMS system in the United States, STAT MedEvac. METHODS: We obtained comprehensive timing, procedure, and vital signs data from STAT MedEvac prehospital electronic patient care records for all adult patients transported to UPMC Health System hospitals in the period of January 2012 through October 2021. We linked these data with hospital electronic health records available through June 2018 to establish length of stay and vital status at discharge. RESULTS: We studied 90,960 transports and matched 62.8% (n = 57,128) to the electronic health record. The average patient age was 58.6 years ( 19 years), and most were male (57.9%). The majority of cases were interfacility transports (77.6%), and the most common general medical category was nontrauma (72.7%). Sixty-one percent of all patients received a prehospital intervention. Overall, hospital mortality was 15%, and the average hospital length of stay (LOS) was 8.8 days ( 10.0 days). Observed trends over time included increases in nontrauma transports, level of severity, and in-hospital mortality. In multivariable models, case severity and medical category correlated with the outcomes of mortality and LOS. CONCLUSION: In the largest standardized nonprofit HEMS system in the United States, patient mortality and hospital LOS increased over time, whereas the proportion of trauma patients and scene runs decreased.

The association of clinical, treatment, and demographic characteristics with rearrest in a national dataset.

INTRODUCTION: Following initial resuscitation from out-of-hospital cardiac arrest, rearrest frequently occurs and has been associated with adverse outcomes. We aimed to identify clinical, treatment, and demographic characteristics associated with prehospital rearrest at the encounter and agency levels. METHODS: Adult non-traumatic cardiac arrest patients who achieved ROSC following EMS resuscitation in the 2018-2021 ESO annual datasets were included in this study. Patients were excluded if they had a documented DNR/POLST or achieved ROSC after bystander CPR only. Rearrest was defined as post-ROSC CPR initiation, administration of ≥ 1 milligram of adrenaline, defibrillation, or a documented non-perfusing rhythm on arrival at the receiving hospital. Multivariable logistic regression modeling was used to evaluate the association between rearrest and case characteristics. Linear regression modeling was used to evaluate the association between agency-level factors (ROSC rate, scene time, and scene termination rate), and rearrest rate. RESULTS: Among the 53,027 cases included, 16,116 (30.4%) experienced rearrest. Factors including longer response intervals, longer 'low-flow' intervals, unwitnessed OHCA, and a lack of bystander CPR were associated with rearrest. Among agencies that treated ≥ 30 patients with outcome data, the agency-level rate of rearrest was inversely associated with agency-level rate of survival to discharge to home (R2 = -0.393, p < 0.001). CONCLUSIONS: This multiagency retrospective study found that factors associated with increased ischaemic burden following OHCA were associated with rearrest. Agency-level rearrest frequency was inversely associated with agency-level survival to home. Interventions that decrease the burden of ischemia sustained by OHCA patients may decrease the rate of rearrest and increase survival.

The Association of Prehospital End-Tidal Carbon Dioxide with Survival Following Out-of-Hospital Cardiac Arrest.

OBJECTIVE: End tidal carbon dioxide (ETCO2) is often used to assess ventilation and perfusion during cardiac arrest resuscitation. However, few data exist evaluating the relationship between ETCO2 values and mortality in the context of contemporary resuscitation practices. We aimed to explore the association between ETCO2 and mortality following out-of-hospital cardiac arrest (OHCA). METHODS: We used the 2018-2021 ESO annual datasets to query all non-traumatic OHCA patients with attempted resuscitation. Patients with documented DNR/POLST, EMS-witnessed arrest, ROSC after bystander CPR only, or < 2 documented ETCO2 values were excluded. The lowest and highest ETCO2 values recorded during the total prehospital interval, in addition to the pre- and post-ROSC intervals for resuscitated patients, were calculated. Multivariable logistic regression models adjusted for age, sex, initial rhythm, witnessed status, bystander CPR, etiology, OHCA location, sodium bicarbonate administration, number of milligrams of epinephrine administered, and response interval were used to evaluate the association between measures of ETCO2 and mortality. RESULTS: Hospital outcome data were available for 14,122 patients, and 2,209 (15.6%) were classified as surviving to discharge. Compared to patients with maximum prehospital ETCO2 values of 30-40 mmHg, odds of mortality were increased for patients with maximum prehospital ETCO2 values of <20 mmHg (aOR: 3.5 [2.1, 5,9]), 20-29 mmHg (aOR: 1.5 [1.1, 2.1]), and >50 mmHg (aOR: 1.5 [1.2, 1.8]). After 20 minutes of ETCO2 monitoring, <12% of patients had ETCO2 values <10 mmHg. This cutpoint was 96.7% specific and 6.9% sensitive for mortality. CONCLUSION: In this dataset, both high and low ETCO2 values were associated with increased mortality. Contemporary resuscitation practices may make low ETCO2 values uncommon, and field termination decision algorithms should not use ETCO2 values in isolation.

The Association of Combined Prehospital Hypotension and Hypoxia with Outcomes following Out-of-Hospital Cardiac Arrest Resuscitation.

BACKGROUND: Prehospital post-resuscitation hypotension and hypoxia have been associated with adverse outcomes in the context of out-of-hospital cardiac arrest (OHCA). We aimed to investigate the association between clinical outcomes and post-resuscitation hypoxia alone, hypotension alone, and combined hypoxia and hypotension. METHODS: We used the 2018-2021 ESO annual datasets to conduct this study. All EMS-treated non-traumatic OHCA patients who had a documented prehospital return of spontaneous circulation (ROSC) and two or more SpO2 readings and systolic blood pressures recorded were evaluated for inclusion. Patients who were less than 18 years of age, pregnant, had a do-not-resuscitate order or similar, achieved ROSC after bystander CPR only, or had an EMS-witnessed cardiac arrest were excluded. Multivariable logistic regression adjusted for standard Utstein factors and highest prehospital Glasgow Coma Scale (GCS) score was used to investigate the association between hypoxia, hypotension, and outcomes. RESULTS: We analyzed data for 17,943 patients, of whom 3,979 had hospital disposition data. Hypotension and hypoxia were not documented in 1,343 (33.8%) patients, 1,144 (28.8%) had only hypoxia documented, 507 (12.7%) had only hypotension documented, and 985 (24.8%) had both hypoxia and hypotension documented. In comparison to patients who did not have documented hypotension or hypoxia, patients who had documented hypoxia (aOR: 1.76 [1.38, 2.24]), documented hypotension (aOR: 3.00 [2.15, 4.18]), and documented hypoxia and hypotension combined (aOR: 4.87 [3.63, 6.53]) had significantly increased mortality. The relationship between mortality and vital sign abnormalities (hypoxia and hypotension > hypotension > hypoxia) was observed in every evaluated subgroup. CONCLUSIONS: In this large dataset, hypotension and hypoxia were independently associated with mortality both alone and in combination. Compared to patients without documented hypotension and hypoxia, patients with documented hypotension and hypoxia had nearly five-fold greater odds of mortality.

Assessment of the Effects of Sodium Nitroprusside Administered Via Intracranial Subdural Catheters on the Cerebral Blood Flow and Lactate Using Dynamic Susceptibility Contrast Magnetic Resonance Imaging and Proton Magnetic Resonance Spectroscopy in a Pig Cardiac Arrest Model.

Background Cerebral blood flow (CBF) is impaired in the early phase after return of spontaneous circulation. Sodium nitroprusside (SNP) administration via intracranial subdural catheters improves cerebral cortical microcirculation. We determined whether the SNP treatment improves CBF in the subcortical tissue and evaluated the effects of this treatment on cerebral lactate. Methods and Results Sixty minutes after return of spontaneous circulation following 14 minutes of untreated cardiac arrest, 14 minipigs randomly received 4 mg SNP or saline via intracranial subdural catheters. CBF was measured in regions of interest within the cerebrum and thalamus using dynamic susceptibility contrast-magnetic resonance imaging. After return of spontaneous circulation, CBF was expressed as a percentage of the baseline value. In the saline group, the %CBF in the regions of interest within the cerebrum remained at approximately 50% until 3.5 hours after return of spontaneous circulation, whereas %CBF in the thalamic regions of interest recovered to approximately 73% at this time point. The percentages of the baseline values in the cortical gray matter and subcortical white matter were higher in the SNP group (group effect P=0.026 and 0.025, respectively) but not in the thalamus. The cerebral lactate/creatine ratio measured using magnetic resonance spectroscopy increased over time in the saline group but not in the SNP group (group-time interaction P=0.035). The thalamic lactate/creatine ratio was similar in the 2 groups. Conclusions SNP administered via intracranial subdural catheters improved CBF not only in the cortical gray matter but also in the subcortical white matter. The CBF improvement by SNP was accompanied by a decrease in cerebral lactate.

Benefits, key protocol components, and considerations for successful implementation of extracorporeal cardiopulmonary resuscitation: a review of the recent literature.

The application of venoarterial extracorporeal membrane oxygenation (ECMO) in patients unresponsive to conventional cardiopulmonary resuscitation (CPR) has significantly increased in recent years. To date, three published randomized trials have investigated the use of extracorporeal CPR (ECPR) in adults with refractory out-of-hospital cardiac arrest. Although these trials reported inconsistent results, they suggest that ECPR may have a significant survival benefit over conventional CPR in selected patients only when performed with strict protocol adherence in experienced emergency medical services-hospital systems. Several studies suggest that identifying suitable ECPR candidates and reducing the time from cardiac arrest to ECMO initiation are key to successful outcomes. Prehospital ECPR or the rendezvous approach may allow more patients to receive ECPR within acceptable timeframes than ECPR initiation on arrival at a capable hospital. ECPR is only one part of the system of care for resuscitation of cardiac arrest victims. Optimizing the chain of survival is critical to improving outcomes of patients receiving ECPR. Further studies are needed to find the optimal strategy for the use of ECPR.

Sodium bicarbonate administration is associated with improved survival in asystolic and PEA Out-of-Hospital cardiac arrest.

BACKGROUND: Sodium bicarbonate ("bicarb") administration in out-of-hospital cardiac arrest (OHCA) is intended to counteract acidosis, although there is limited clinical evidence to support its routine administration. We sought to analyze the association of bicarb with resuscitation outcomes in non-traumatic OHCA. METHODS: Records were obtained from the 2019-2020 ESO Data Collaborative prehospital electronic health record database, spanning 1,322 agencies in 50 states. OHCAs with resuscitations lasting 5-40 minutes were stratified by presenting ECG rhythm (VF/VT, pulseless electrical activity (PEA), asystole) for analysis. The outcomes of any prehospital ROSC and survival to discharge were compared by bicarb status using propensity score matching and logistic regressions with/without adjustment. RESULTS: We analyzed 23,567 records, 6,663 (28.3 %) of which included bicarb administration. Most patients presented in asystole (67.4 %), followed by PEA (16.6 %), and VF/VT (15.1 %). In the propensity-matched cohort, ROSC was higher in the bicarb group for the asystole group (bicarb 10.6 % vs control 8.8 %; p = 0.013), without differences in the PEA or VF/VT groups. Survival was higher in the bicarb group for asystole (bicarb 3.3 % vs control 2.4 %; p = 0.020) and for PEA (bicarb 8.1 % vs control 5.4 %; p = 0.034), without differences in the VF/VT group. These results were consistent across adjusted/unadjusted logistic regression analyses: bicarb was associated with ROSC and survival in asystole [uOR (95 % CI): ROSC 1.23 (1.04-1.44), survival 1.40 (1.05-1.87)] and with survival in PEA (1.54 (1.03-2.31). CONCLUSIONS: Bicarb was associated with survival in non-shockable rhythms and ROSC in asystole. Findings from this observational study should be corroborated with prospective randomized work.

Disparities in Out-of-Hospital Cardiac Arrest Treatment and Outcomes of Males and Females.

Background: Previous studies comparing the treatment of males and females during out-of-hospital cardiac arrests (OHCA) have been contradictory. Understanding differences in treatment and outcomes is important to assuring appropriate care to both sexes.Hypothesis: Females with OHCA receive fewer interventions and have lower rates of survival to hospital discharge when compared to males with OHCA.Methods: We conducted a secondary analysis of the Resuscitation Outcomes Consortium (ROC) Cardiac Arrest Epistry 3 data collected from April 2011 to June 2015. We included all OHCA cases treated by emergency medical services (EMS) who had sex recorded. We analyzed 36 treatment and outcome variables. We calculated descriptive statistics and compared treatment and outcomes between males and females using chi-square and t-tests. We performed multivariate regressions adjusting for baseline characteristics.Results: Of 120,306 total subjects, 65,241 were included (23,924 female, 41,317 male). Females were 9.9% less likely to have OHCA in public, 10.9% less likely to have a shockable rhythm, and were a median of 5 years older. In the unadjusted analysis, females were defibrillated by EMS less often (OR 1.81, 95% CI [1.74, 1.88]), received epinephrine less often (OR 1.15, 95% CI [1.10, 1.19]), took an average of 67 seconds longer to achieve first return of spontaneous circulation (ROSC) (coefficient -66.75, 95% CI [-83.98, -49.52]), and had 2.2% lower survival to emergency department (ED) arrival (OR 1.09, 95% CI [1.06, 1.13]). After adjusting for age, bystander CPR, witness status, episode location, and initial rhythm, the odds of surviving to hospital discharge were higher in males (OR 1.12, 95% CI [1.05, 1.21]), and the odds of surviving to ED arrival favored females (OR 0.87, 95% CI [0.84-0.90]). Additionally, odds of receiving epinephrine (OR 1.22, 95% CI [1.16, 1.27]) and odds of receiving defibrillation (OR 1.36, 95% CI [1.29, 1.44]) were both higher in males, and time to achieve first ROSC was no longer associated with sex (p = 0.114, 95% CI [-3.32, 31.11]).Conclusions: After adjusting for case characteristics, females were less likely to receive some key treatments, including epinephrine and defibrillation. Females also had poorer survival to hospital discharge but had higher odds of surviving to ED arrival.

Association of prehospital hypotension depth and dose with survival following out-of-hospital cardiac arrest.

INTRODUCTION: Hypotension following resuscitation from out-of-hospital cardiac arrest (OHCA) may cause harm by exacerbating secondary brain injury; however, limited research has explored this relationship. Our objective was to examine the association between duration and depth of prehospital post return of spontaneous circulation (ROSC) hypotension and survival. METHODS: We utilized the 2019 and 2020 ESO Data Collaborative public use research data sets for this study (ESO, Austin, TX). Hypotension dose (mmHg*min.), average prehospital systolic blood pressure (SBP), and lowest recorded prehospital SBP were calculated. The association of these measures with survival to home (STH) and rearrest were explored using multivariable logistic regression. Time to hypotension resolution analyses by hypotension management strategy (push dose vasopressors, vasopressor infusion, or fluid only) were conducted using adjusted Cox proportional hazards models. RESULTS: 17,280 OHCA patients met inclusion criteria, of which 3,345 had associated hospital outcome data. Over one-third (37.8%; 6,526/17,280) of all patients had at least one recorded SBP below 90 mmHg. When modeled continuously, average prehospital SBP (1.19 [1.15, 1.23] per 10 mmHg), lowest prehospital SBP (1.20 [1.17, 1.24] per 10 mmHg), and hypotension dose (0.995 [0.993, 0.996] per mmHg*min.) were independently associated with STH. Differences in hypotension management were not associated with differences in survival or time to hypotension resolution. CONCLUSION: Severity and duration of hypotension were significantly associated with worse outcomes in this dataset. Defining a threshold for hypotension requiring treatment above the classical SBP threshold of 90 mmHg may be warranted in the setting of prehospital post-resuscitation care.

Association of prehospital post-resuscitation peripheral oxygen saturation with survival following out-of-hospital cardiac arrest.

BACKGROUND: Hypoxia and hyperoxia following resuscitation from out-of-hospital cardiac arrest (OHCA)may cause harm by exacerbating secondary brain injury. Our objective was to retrospectively examine theassociationof prehospital post-ROSC hypoxia and hyperoxia with the primary outcome of survival to discharge home. METHODS: We utilized the 2019-2021 ESO Data Collaborative public use research datasets for this study (ESO, Austin, TX). Average prehospital SpO2, lowest recorded prehospital SpO2, and hypoxia dose were calculated for each patient. Theassociationof these measures with survival was explored using multivariable logistic regression. We also evaluated theassociationof American Heart Association (AHA) and European Resuscitation Council (ERC) recommended post-ROSC SpO2 target ranges with outcome. RESULTS: After application of exclusion criteria, 19,023 patients were included in this study. Of these, 52.3% experienced at least one episode of post-ROSC hypoxia (lowest SpO2 < 90%) and 19.6% experienced hyperoxia (average SpO2 > 98%). In comparison to normoxic patients, patients who were hypoxic on average (AHA aOR: 0.31 [0.25, 0.38]; ERC aOR: 0.34 [0.28, 0.42]) and patients who had a hypoxic lowest recorded SpO2 (AHA aOR: 0.48 [0.39, 0.59]; ERC aOR: 0.52 [0.42, 0.64]) had lower adjusted odds of survival. Patients who had a hyperoxic average SpO2 (AHA aOR: 0.75 [0.59, 0.96]; ERC aOR: 0.68 [0.53, 0.88]) and patients who had a hyperoxic lowest recorded SpO2 (AHA aOR: 0.66 [0.48, 0.92]; ERC aOR: 0.65 [0.46, 0.92]) also had lower adjusted odds of survival. CONCLUSION: Prehospital post-ROSC hypoxia and hyperoxia were associated with worse outcomes in this dataset.

Sudden Electrocardiogram Rhythm Changes after Return of Spontaneous Circulation in Porcine Models of Out-of-Hospital Cardiac Arrest: A Phenomenological Report.

BACKGROUND: Observation of the electrocardiogram (ECG) immediately following return of spontaneous circulation (ROSC) in resuscitated swine has revealed the interesting phenomenon of sudden ECG rhythm changes (SERC) that occur in the absence of pharmacological, surgical, or other medical interventions. OBJECTIVE: We sought to identify, quantify, and characterize post-ROSC SERC in successfully resuscitated swine. METHODS: We reviewed all LabChart data from resuscitated approximately 4- to 6-month-old swine used for various experimental protocols from 2006 to 2019. We identified those that achieved sustained ROSC and analyzed their entire post-ROSC periods for evidence of SERC in the ECG, and arterial and venous pressure tracings. Presence or absence of SERC was confirmed independently by two reviewers (ACK, DDS). We measured the interval from ROSC to first SERC, analyzed the following metrics, and calculated the change from 60 sec pre-SERC (or from ROSC if less than 60 sec) to 60 sec post-SERC: heart rate, central arterial pressure (CAP), and central venous pressure (CVP). RESULTS: A total of 52 pigs achieved and sustained ROSC. Of these, we confirmed at least one SERC in 25 (48.1%). Two pigs (8%) each had two unique SERC events. Median interval from ROSC to first SERC was 3.8 min (inter-quartile range 1.0-6.9 min; range 16 sec to 67.5 min). We observed two distinct types of SERC: type 1) the post-SERC heart rate and arterial pressure increased (72% of cases); and type 2) the post-SERC heart rate and arterial pressure decreased (28% of cases). For type 1 cases, the mean (standard deviation [SD]) heart rate increased by 33.6 (45.7) beats per minute (bpm). The mean (SD) CAP increased by 20.6 (19.2) mmHg. For type 2 cases, the mean (SD) heart rate decreased by 39.7 (62.3) bpm. The mean (SD) CAP decreased by 21.9 (15.6) mmHg. CONCLUSIONS: SERC occurred in nearly half of all cases with sustained ROSC and can occur multiple times per case. First SERC most often occurred within the first 4 minutes following ROSC. Heart rate, CAP, and CVP changed at the moment of SERC. We are proceeding to examine whether this phenomenon occurs in humans post-cardiac arrest and ROSC.

Establishing a multicenter, preclinical consortium in resuscitation: A pilot experimental trial evaluating epinephrine in cardiac arrest.

BACKGROUND: Large animal studies are an important step in the translation pathway, but single laboratory experiments do not replicate the variability in patient populations. Our objective was to demonstrate the feasibility of performing a multicenter, preclinical, randomized, double-blinded, placebo-controlled cardiac arrest trial. We evaluated the effect of epinephrine on coronary perfusion pressure (CPP) as previous single laboratory studies have reported mixed results. METHODS: Forty-five swine from 5 different laboratories (Ann Arbor, MI; Baltimore, MD; Los Angeles, CA; Pittsburgh, PA; Toronto, ON) using a standard treatment protocol. Ventricular fibrillation was induced and left untreated for 6 min before starting continuous cardiopulmonary resuscitation (CPR). After 2 min of CPR, 9 animals from each lab were randomized to 1 of 3 interventions given over 12 minutes: (1) Continuous IV epinephrine infusion (0.00375 mg/kg/min) with placebo IV normal saline (NS) boluses every 4 min, (2) Continuous placebo IV NS infusion with IV epinephrine boluses (0.015 mg/kg) every 4 min or (3) Placebo IV NS for both infusion and boluses. The primary outcome was mean CPP during the 12 mins of drug therapy. RESULTS: There were no significant differences in mean CPP between the three groups: 14.4 ± 6.8 mmHg (epinephrine Infusion), 16.9 ± 5.9 mmHg (epinephrine bolus), and 14.4 ± 5.5 mmHg (placebo) (p = NS). Sensitivity analysis demonstrated inter-laboratory variability in the magnitude of the treatment effect (p = 0.004). CONCLUSION: This study demonstrated the feasibility of performing a multicenter, preclinical, randomized, double-blinded cardiac arrest trials. Standard dose epinephrine by bolus or continuous infusion did not increase coronary perfusion pressure during CPR when compared to placebo.

PulsePoint dispatch associated patient characteristics and prehospital outcomes in a mid-sized metropolitan area.

BACKGROUND: Mobile phone-based dispatch of volunteers to out-of-hospital cardiac arrests (OHCA) has been shown to increase the likelihood of early CPR and AED application. In the United States, limited characterization of patients encountered as a result of such systems exists. AIMS: Examine prehospital case characteristics and outcomes from a multi-year deployment of PulsePoint Respond in Pittsburgh, Pennsylvania. METHODS: PulsePoint event timing, location, and associated prehospital electronic health records (ePCRs) were obtained for EMS-encountered OHCA cases that did and did not generate PulsePoint alerts within the service area of Pittsburgh EMS from July 2016 to October 2020. ePCRs were reviewed and OHCA case characteristics were extracted according to the Utstein template. PulsePoint-associated OHCA and non-PulsePoint-associated OHCA were compared. RESULTS: Of 840 total PulsePoint dispatches, 64 (7.6%) were for OHCA associated with a resuscitation attempt. Forty-one (64.1%) were witnessed, 38 (59.4%) received bystander CPR, and 13 (20.0%) of these patients had an AED applied prior to EMS arrival. Twenty-seven (39.7%) had an initial shockable rhythm, and 31 (48.4%) patients achieved ROSC in the field. In the city of Pittsburgh, there were 1229 total OHCA during the study period, with an estimated 29.6% occurring in public. When PulsePoint-associated and publicly occurring non-PulsePoint-associated OHCA were compared, baseline characteristics (age, sex, witnessed status) were similar, but PulsePoint-associated OHCA received more bystander CPR (p = 0.008). CONCLUSIONS: A minority of PulsePoint dispatches in Pittsburgh were triggered by true OHCA. The majority of OHCA during the study period occurred within private residences where PulsePoint responders are not currently dispatched. PulsePoint dispatches were associated with prognostically favorable OHCA characteristics and increased bystander CPR performance.

Injury characteristics and hemodynamics associated with guideline-compliant CPR in a pediatric porcine cardiac arrest model.

BACKGROUND: Guidelines for depth of chest compressions in pediatric cardiopulmonary resuscitation (CPR) are based on sparse evidence. OBJECTIVE: We sought to evaluate the performance of the two most widely recommended chest compression depth levels for pediatric CPR (1.5 in. and 1/3 the anterior-posterior diameter- APd) in a controlled swine model of asphyxial cardiac arrest. METHODS: We executed a 2-group, randomized laboratory study with an adaptive design allowing early termination for overwhelming injury or benefit. Forty mixed-breed domestic swine (mean weight = 26 kg) were sedated, anesthetized and paralyzed along with endotracheal intubation and mechanical ventilation. Asphyxial cardiac arrest was induced with fentanyl overdose. Animals were untreated for 9 min followed by mechanical CPR with a target depth of 1.5 in. or 1/3 the APd. Advanced life support drugs were administered IV after 4 min of basic resuscitation followed by defibrillation at 14 min. The primary outcomes were return of spontaneous circulation (ROSC), hemodynamics and CPR-related injury severity. RESULTS: Enrollment in the 1/3 APd group was stopped early due to overwhelming differences in injury. Twenty-three animals were assigned to the 1.5 in. group and 15 assigned to the 1/3 APd group, per an adaptive group design. The 1/3 APd group had increased frequency of rib fracture (6.7 vs 1.7, p < 0.001) and higher proportions of several anatomic injury markers than the 1.5 in. group, including sternal fracture, hemothorax and blood in the endotracheal tube (p < 0.001). ROSC and hemodynamic measures were similar between groups. CONCLUSION: In this pediatric model of cardiac arrest, chest compressions to 1/3APd were more harmful without a concurrent benefit for resuscitation outcomes compared to the 1.5 in. compression group.

Early cytotoxic lymphocyte localization to the brain following resuscitation in a porcine model of asphyxial cardiac arrest: A pilot study.

INTRODUCTION: Out-of-hospital cardiac arrest (OHCA) is a major cause of morbidity and mortality in the US. Of major concern is a lack of therapies to mitigate associated brain injury. Immune cell infiltration (ICI) into the brain, which may exacerbate injury post-resuscitation, is one possible therapeutic target, although the post-OHCA immune response has not been fully characterized. OBJECTIVE: In this pilot study, we aimed to detect early post-resuscitation cytotoxic lymphocyte ICI in porcine brain using a model of opioid-mediated asphyxial OHCA. METHODS: Ten young, healthy swine (26.7+/-3.4 kg) were sedated, anaesthetized and paralyzed. In eight of the animals, this was followed by induction of asphyxial OHCA via fentanyl bolus and concurrent airway occlusion. The remaining two 'sham' animals were instrumented but did not undergo asphyxia. After nine minutes of asphyxia, mechanical CPR and manual ventilations were started, in an initial BLS followed by ALS configuration. At termination of resuscitation or euthanasia, the whole brain was removed. Immune cells were extracted and analyzed via flow cytometry. RESULTS: 304 +/- 62.2 cells/g were discovered to be CD8 single positive cells in animals that achieved ROSC, 481 +/- 274.4 cells/g in animals that did not achieve ROSC, and 40 +/- 11.31 cells/g in sham animals. CD8 single positive cells made up 0.473 +/- 0.24% of detected cells in animals that achieved ROSC, 0.395 +/- 0.062% in animals that did not achieve ROSC, and 0.19 +/- 0.014% in sham animals (No ROSC vs Sham, p = 0.012). CONCLUSIONS: These data suggest that cytotoxic lymphocytes may be localizing to the brain during cardiac arrest resuscitation.