Factors associated with sustained return of spontaneous circulation in children after out-of-hospital cardiac arrest of noncardiac origin

Purpose

The study aimed to determine the factors predictive of sustained return of spontaneous circulation (ROSC) in children with out-of-hospital cardiac arrest (OHCA) of noncardiac origin.

Methods

Eighty children were included in this retrospective study. The variables that lead to sustained ROSC and those that do not lead to sustained ROSC were analyzed. Survival analyses, including chance of achieving sustained ROSC and sum duration of ROSC, were conducted according to the duration of in-hospital cardiopulmonary resuscitation (CPR).

Results

Etiologies of noncardiac OHCA differed significantly across different age groups (P < .001). Only 8.8% of children had initial arrest rhythms that were shockable. Predictors of sustained ROSC included the initial cardiac rhythm (P = .002), a shorter period between collapse and the first chest compression (P = .002), a shorter in-hospital CPR duration (P = .004), and prehospital CPR (P = .007). In children where ROSC was initially sustained, those with in-hospital CPR of more than 20 minutes, ROSC was sustained for less time (P < .001).

Conclusions

Few children with noncardiac OHCA present with shockable cardiac rhythms. Furthermore, long-term ROSC is difficult to maintain in children who receive in-hospital CPR for more than 20 minutes.     

Doubling survival and improving clinical outcomes using a left ventricular assist device instead of chest compressions for resuscitation after prolonged cardiac arrest: a large animal study

IntroductionDespite improvements in pre-hospital and post-arrest critical care, sudden cardiac arrest (CA) remains one of the leading causes of death. Improving circulation during cardiopulmonary resuscitation (CPR) may improve survival rates and long-term clinical outcomes after CA.MethodsIn a porcine model, we compared standard CPR (sCPR; n =10) with CPR using an intravascular cardiac assist device without additional chest compressions (iCPR; n =10) following 10 minutes of electrically induced ventricular fibrillation (VF). In a separate crossover experiment, 10 additional pigs were subjected to 10 minutes of VF and 6 minutes of sCPR; the iCPR device was then implanted if a return of spontaneous circulation (ROSC) was not achieved using sCPR. Animals were evaluated in respect to intra- and post-arrest hemodynamics, survival, functional outcome and cerebral and myocardial lesions following CPR. We hypothesized that iCPR would result in more frequent ROSC and better functional recovery than sCPR.ResultsiCPR produced a mean flow of 1.36 ± 0.02 L/min, leading to significantly higher coronary perfusion pressure (CPP) values during the early period of CPR (22 ± 10 mmHg vs. 9 ± 5 mmHg, P ≤0.01, 1 minute after start of CPR; 20 ± 11 mmHg vs. 10 ± 7 mmHg, P =0.03, 2 minutes after start of CPR), resulting in high ROSC rates (100% in iCPR vs. 50% in sCPR animals; P =0.03). iCPR animals showed significantly lower serum S100 levels at 10 and 30 minutes following ROSC (3.5 ± 0.6 ng/ml vs. 7.4 ± 3.0 ng/ml 30 minutes after ROSC; P ≤0.01), as well as superior clinical outcomes based on overall performance categories (2.9 ± 1.0 vs. 4.6 ± 0.8 on day 1; P ≤0.01). In crossover experiments, 80% of animals required treatment with iCPR after failed sCPR. Notably, ROSC was still achieved in six of the remaining eight animals (75%) after a total of 22.8 ± 5.1 minutes of ischemia.ConclusionsIn a model of prolonged cardiac arrest, the use of iCPR instead of sCPR improved CPP and doubled ROSC rates, translating into improved clinical outcomes.     

P RECIPITOUS B REECH D ELIVERY OF T WINS

Abstract

Introduction. The amount of myocardial perfusion required for successful defibrillation after prolonged cardiac arrest is not known. Coronary perfusion pressure (CPP) is a surrogate for myocardial perfusion. One limited clinical study reported that a threshold of 15 mmHg was necessary for return of spontaneous circulation (ROSC), and that CPP was predictive of ROSC. A distinction between threshold and dose of CPP has not been reported. Objective. To test the hypothesis that swine achieving ROSC will have higher preshock mean CPP and higher preshock area under the CPP curve (AUC) than swine not attaining ROSC. Methods. Data from four similar swine cardiac arrest studies were retrospectively pooled. Animals had undergone 8–11 minutes of untreated ventricular fibrillation, 2 minutes of mechanical cardiopulmonary resuscitation (CPR), administration of drugs, and 3 more minutes of CPR prior to the first shock. Mean CPP ± standard error of the mean (SEM) was derived from the last 20 compressions of each 30-second epoch of CPR and compared between ROSC/no-ROSC groups by repeated-measures analysis of variance (RM-ANOVA). AUC for all compressions delivered over the 5 minutes was calculated by direct summation and compared by Kruskal-Wallis test. Prediction of ROSC was assessed by logistic regression. Results. Throughout the first 5 minutes of CPR (n = 80), mean CPP ± SEM was consistently higher in animals with ROSC (n = 63) (maximum CPP 41.2 ± 0.6 mmHg) than animals with no ROSC (maximum CPP 20.1 ± 0.3 mmHg) (p = 0.0001). Animals with ROSC received more total reperfusion (43.9 ± 17.6 mmHg × 10²) than animals without ROSC (21.4 ± 13.7 mmHg × 10²) (p < 0.001). Two regression models identified CPP (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.05, 1.18) and AUC (OR 1.10; 95% CI 1.05, 1.16) as predictors of ROSC. Experimental study also predicted ROSC in each model (OR 1.70; 95% CI 1.15, 2.50; and OR 1.59; 95% CI 1.12, 2.25, respectively). Conclusion. Higher CPP threshold and dose are associated with and predictive of ROSC.     

Effects of an Impedance Threshold Device on Hemodynamics andRestoration of Spontaneous Circulation in Prolonged Porcine Ventricular Fibrillation

Background. An impedance threshold device (ITD) has been designed to enhance circulation during CPR by creating a negative intrathoracic pressure during the relaxation phase of chest compression. Hypothesis. We sought to determine the effects of the ITD on coronary perfusion pressure (CPP), return of spontaneous circulation (ROSC), andshort-term survival (20 minutes after ROSC). We hypothesized that the ITD would improve all 3 variables when compared to standard CPR. Methods. Using a case-control design nested within a randomized primary study, we compared CPR with the ITD (ITD-CPR) to standard CPR without the device (S-CPR). We systematically assigned 36 domestic swine, weighing 23–29 kg, (18 per group) to resuscitation with either ITD-CPR or S-CPR after 8 minutes of untreated ventricular fibrillation (VF). At minute 8, mechanical chest compression andventilation began, anddrugs (0.1 mg/kg epinephrine, 40U vasopressin, 1.0 mg propranolol, 1 mEq/kg sodium bicarbonate) were given. The first rescue shock (150J biphasic) was delivered at minute 11 of VF. We recorded CPP, ROSC (systolic pressure > 80 mmHg sustained for 60 s continuously), andsurvival. Data were analyzed with Fisher's exact test andgeneralized estimating equations (GEE), with alpha = 0.05. Results. We analyzed 3,150 compressions. CPP for the ITD-CPR group (28.1 mmHg [95% CI 27–29.3 mmHg]), did not differ from the S-CPR group (32.3 mmHg [95% CI 31.2–33.4 mmHg]). ROSC occurred in 6/18 (33%) animals in the ITD-CPR, and14/18 (78%) in the S-CPR group (p = 0.02). Survival occurred in 3/18 (17%) ITD-CPR and13/18 (72%) S-CPR group (p = 0.003). Conclusions. ITD-CPR did not improve CPP compared to S-CPR. ROSC andsurvival were significantly lower with ITD-CPR.     

Pharmacokinetic effects of endotracheal,intraosseous, and intravenous epinephrine in a swine model of traumatic cardiac arrest

IntroductionLimited prospective data exist regarding epinephrine's controversial role in managing traumatic cardiac arrest (TCA). This study compared the maximum concentration (Cmax), time to maximum concentration (Tmax), plasma concentration over time, return of spontaneous circulation (ROSC), time to ROSC, and odds of ROSC of epinephrine administered by the endotracheal (ETT), intraosseous (IO), and intravenous (IV) routes in a swine TCA model.MethodsForty-nine Yorkshire-cross swine were assigned to seven groups: ETT, tibial IO (TIO), sternal IO (SIO), humeral IO (HIO), IV, CPR with defibrillation (CPRD), and CPR only. Swine were exsanguinated 31% of their blood volume and cardiac arrest induced. Chest compressions began 2 min post-arrest. At 4 min post-arrest, 1 mg epinephrine was administered, and blood specimens collected over 4 min. Resuscitation continued until ROSC or 30 min elapsed.ResultsThe Cmax of IV epinephrine was significantly higher than the TIO group (P = 0.049). No other differences in Cmax, Tmax, ROSC, and time to ROSC existed between the epinephrine groups (P > 0.05). Epinephrine levels were detectable in two of seven ETT swine. No significant difference in ROSC existed between the epinephrine groups and CPRD group (P > 0.05). Significant differences in ROSC existed between all groups and the CPR only group (P < 0.05). No significant differences in odds of ROSC were noted.ConclusionsThe pharmacokinetics of IV, HIO, and SIO epinephrine were comparable. Endotracheal epinephrine absorption was highly variable and unreliable compared to IV and IO epinephrine. Epinephrine appeared to have a lesser role than volume replacement in resuscitating TCA.     

Changes of end-tidal carbon dioxide during cardiopulmonary resuscitation from ventricular fibrillation versus asphyxial cardiac arrest

BACKGROUND:

Partial pressure of end-tidal carbon dioxide (P_ETCO₂) has been used to monitor the effectiveness of precordial compression (PC) and regarded as a prognostic value of outcomes in cardiopulmonary resuscitation (CPR). This study was to investigate changes of P_ETCO₂ during CPR in rats with ventricular fibrillation (VF) versus asphyxial cardiac arrest.

METHODS:

Sixty-two male Sprague-Dawley (SD) rats were randomly divided into an asphyxial group (n=32) and a VF group (n=30). P_ETCO₂ was measured during CPR from a 6-minute period of VF or asphyxial cardiac arrest.

RESULTS:

The initial values of P_ETCO₂ immediately after PC in the VF group were significantly lower than those in the asphyxial group (12.8±4.87 mmHg vs. 49.2±8.13 mmHg, P=0.000). In the VF group, the values of P_ETCO₂ after 6 minutes of PC were significantly higher in rats with return of spontaneous circulation (ROSC), compared with those in rats without ROSC (16.5±3.07 mmHg vs. 13.2±2.62 mmHg, P=0.004). In the asphyxial group, the values of P_ETCO₂ after 2 minutes of PC in rats with ROSC were significantly higher than those in rats without ROSC (20.8±3.24 mmHg vs. 13.9±1.50 mmHg, P=0.000). Receiver operator characteristic (ROC) curves of P_ETCO₂ showed significant sensitivity and specificity for predicting ROSC in VF versus asphyxial cardiac arrest.

CONCLUSIONS:

The initial values of P_ETCO₂ immediately after CPR may be helpful in differentiating the causes of cardiac arrest. Changes of P_ETCO₂ during CPR can predict outcomes of CPR.KEY WORDS: Partial pressure of end-tidal carbon dioxide, Cardiac arrest, Cardiopulmonary resuscitation, Return of spontaneous circulation, Rats     

The impact of response time reliability on CPR incidence and resuscitation success: a benchmark study from the German Resuscitation Registry

Introduction

Sudden cardiac arrest is one of the most frequent causes of death in the world. In highly qualified emergency medical service (EMS) systems, including well-trained emergency physicians, spontaneous circulation may be restored in up to 53% of patients at least until admission to hospital. Compared with these highly qualified EMS systems, markedly lower success rates are observed in other systems. These data clearly show that there are considerable differences between EMS systems concerning treatment success following cardiac arrest and resuscitation, although in all systems international guidelines for resuscitation are used. In this study, we investigated the impact of response time reliability (RTR) on cardiopulmonary resuscitation (CPR) incidence and resuscitation success by using the return of spontaneous circulation (ROSC) after cardiac arrest (RACA) scores and data from seven German EMS systems participating in the German Resuscitation Registry.

Methods

Anonymised patient data after out-of-hospital cardiac arrest gathered from seven EMS systems in Germany from 2006 to 2009 were analysed with regard to socioeconomic factors (population, area and EMS unit-hours), process quality (RTR, CPR incidence, special CPR measures and prehospital cooling), patient factors (age, gender, cause of cardiac arrest and bystander CPR). End points were defined as ROSC, admission to hospital, 24-hour survival and hospital discharge rate. χ² tests, odds ratios and the Bonferroni correction were used for statistical analyses.

Results

Our present study comprised 2,330 prehospital CPR patients at seven centres. The incidence of sudden cardiac arrest ranged from 36.0 to 65.1/100,000 inhabitants/year. We identified two EMS systems (RTR < 70%) that reached patients within 8 minutes of the call to the dispatch centre 62.0% and 65.6% of the time, respectively. The other five EMS systems (RTR > 70%) reached patients within 8 minutes of the call to the dispatch centre 70.4% up to 95.5% of the time. EMS systems arriving relatively later at the patients side (RTR < 70%) initiate CPR less frequently and admit fewer patients alive to hospital (calculated per 100,000 inhabitants/year) (CPR incidence (1/100,000 inhabitants/year) RTR > 70% = 57.2 vs RTR < 70% = 36.1, OR = 1.586 (99% CI = 1.383 to 1.819); P < 0.01) (admitted to hospital with ROSC (1/100,000 inhabitants/year) RTR > 70% = 24.4 vs RTR < 70% = 15.6, OR = 1.57 (99% CI = 1.274 to 1.935); P < 0.01). Using ROSC rate and the multivariate RACA score to predict outcomes, we found that the two groups did not differ, but ROSC rates were higher than predicted in both groups (ROSC RTR > 70% = 46.6% vs RTR < 70% = 47.3%, OR = 0.971 (95% CI = 0.787 to 1.196); P = n.s.) (ROSC RACA RTR > 70% = 42.4% vs RTR < 70% = 39.5%, OR = 1.127 (95% CI = 0.911 to 1.395); P = n.s.)

Conclusion

This study demonstrates that, on the level of EMS systems, faster ones more often initiate CPR and increase the number of patients admitted to hospital alive. Furthermore, we show that, with very different approaches, all centres that adhere to and are intensely trained according to the 2005 European Resuscitation Council guidelines are superior and, on the basis of international comparisons, achieve excellent success rates following CPR.     

Automated pupillometry helps monitor the efficacy of cardiopulmonary resuscitation and predict return of spontaneous circulation

BackgroundWe investigated the effectiveness of automated pupillometry on monitoring cardiopulmonary resuscitation (CPR) and predicting return of spontaneous circulation (ROSC) in a swine model of cardiac arrest (CA).MethodsSixteen male domestic pigs were included. Traditional indices including coronary perfusion pressure (CPP), end-tidal carbon dioxide (ETCO₂), regional cerebral tissue oxygen saturation (rSO₂) and carotid blood flow (CBF) were continuously monitored throughout the experiment. In addition, the pupillary parameters including the initial pupil size before constriction (Init, maximum diameter), the end pupil size at peak constriction (End, minimum diameter), and percentage of change (%PLR) were measured by an automated quantitative pupillometer at baseline, at 1, 4, 7 min during CA, and at 1, 4, 7 min during CPR.ResultsROSC was achieved in 11/16 animals. The levels of CPP, ETCO₂, rSO₂ and CBF were significantly greater during CPR in resuscitated animals than those non-resuscitated ones. Init and End were decreased and %PLR was increased during CPR in resuscitated animals when compared with those non-resuscitated ones. There were moderate to good significant correlations between traditional indices and Init, End, and %PLR (|r| = 0.46–0.78, all P < 0.001). Furthermore, comparable performance was also achieved by automated pupillometry (AUCs of Init, End and %PLR were 0.821, 0.873 and 0.821, respectively, all P < 0.05) compared with the traditional indices (AUCs = 0.809–0.946).ConclusionThe automated pupillometry may serve as an effective surrogate method to monitor cardiopulmonary resuscitation efficacy and predict ROSC in a swine model of cardiac arrest.     

Inhaled nitric oxide improves transpulmonary blood flow and clinical outcomes after prolonged cardiac arrest: a large animal study

IntroductionThe probability to achieve a return of spontaneous circulation (ROSC) after cardiac arrest can be improved by optimizing circulation during cardiopulomonary resuscitation using a percutaneous left ventricular assist device (iCPR). Inhaled nitric oxide may facilitate transpulmonary blood flow during iCPR and may therefore improve organ perfusion and outcome.MethodsVentricular fibrillation was electrically induced in 20 anesthetized male pigs. Animals were left untreated for 10 minutes before iCPR was attempted. Subjects received either 20 ppm of inhaled nitric oxide (iNO, n = 10) or 0 ppm iNO (Control, n = 10), simultaneously started with iCPR until 5 hours following ROSC. Animals were weaned from the respirator and followed up for five days using overall performance categories (OPC) and a spatial memory task. On day six, all animals were anesthetized again, and brains were harvested for neurohistopathologic evaluation.ResultsAll animals in both groups achieved ROSC. Administration of iNO markedly increased iCPR flow during CPR (iNO: 1.81 ± 0.30 vs Control: 1.64 ± 0.51 L/min, p < 0.001), leading to significantly higher coronary perfusion pressure (CPP) during the 6 minutes of CPR (25 ± 13 vs 16 ± 6 mmHg, p = 0.002). iNO-treated animals showed significantly lower S-100 serum levels thirty minutes post ROSC (0.26 ± 0.09 vs 0.38 ± 0.15 ng/mL, p = 0.048), as well as lower blood glucose levels 120–360 minutes following ROSC. Lower S-100 serum levels were reflected by superior clinical outcome of iNO-treated animals as estimated with OPC (3 ± 2 vs. 5 ± 1, p = 0.036 on days 3 to 5). Three out of ten iNO-treated, but none of the Control animals were able to successfully participate in the spatial memory task. Neurohistopathological examination of vulnerable cerebral structures revealed a trend towards less cerebral lesions in neocortex, archicortex, and striatum in iNO-treated animals compared to Controls.ConclusionsIn pigs resuscitated with mechanically-assisted CPR from prolonged cardiac arrest, the administration of 20 ppm iNO during and following iCPR improved transpulmonary blood flow, leading to improved clinical neurological outcomes.     

Initial end-tidal carbon dioxide as a prognostic indicator for inpatient PEA arrest

AimInvestigate the relationship of initial PetCO2 values of patients during inpatient pulseless electrical activity (PEA) cardiopulmonary arrest with return of spontaneous circulation (ROSC) and survival to discharge.MethodsThis study was performed in two urban, academic inpatient hospitals. Patients were enrolled from July 2009 to July 2013. A comprehensive database of all inpatient resuscitative events is maintained at these institutions, including demographic, clinical, and outcomes data. Arrests are stratified by primary etiology of arrest using a priori criteria. Inpatients with PEA arrest for whom recorded PetCO2 was available were included in the analysis. Capnography data obtained after ROSC and/or more than 10 min after initiation of CPR were excluded. Multivariable logistic regression was used to explore the association between initial PetCO2 >20 mmHg and both ROSC and survival-to-discharge.ResultsA total of 50 patients with PEA arrest and pre-ROSC capnography were analyzed. CPR continued an average of 11.8 min after initial PetCO2 was recorded confirming absence of ROSC at time of measurement. Initial PetCO2 was higher in patients with versus without eventual ROSC (25.3 ± 14.4 mmHg versus 13.4 ± 6.9 mmHg, P = 0.003). After adjusting for age, gender, and arrest location (ICU versus non-ICU), initial PetCO2 >20 mmHg was associated with increased likelihood of ROSC (adjusted OR 4.8, 95% CI 1.2–19.2, P = 0.028). Initial PetCO2 was not significantly associated with survival-to-discharge (P = 0.251).ConclusionsInitial PetCO2 >20 mmHg during CPR was associated with ROSC but not survival-to-discharge among inpatient PEA arrest victims. This analysis is limited by relatively small sample size.     

Impact of dispatcher assisted CPR on ROSC rates: A National Cohort Study

IntroductionOut of hospital cardiac arrest (OHCA) is a leading cause of mortality. Bystander CPR is associated with increased OHCA survival rates. Dispatcher assisted CPR (DA-CPR) increases rates of bystander CPR, shockable rhythm prevalence, and improves ROSC rates. The aim of this article was to quantify and qualify DA-CPR (acceptance/rejection), ROSC, shockable rhythms, and associations between factors as seen in MDA, Israel, during 2018.MethodsAll 2018 OHCA incidents in Israel's national EMS database were studied retrospectively. We identified rates and reasons for DA-CPR acceptance or rejection. Reasons DA-CPR was rejected/non-feasible by caller were categorized into 5 groups. ROSC was the primary outcome. We created two study groups: 1) No DA-CPR (n = 542). 2) DA-CPR & team CPR (n = 1768).ResultsDA-CPR was accepted by caller 76.5% of incidents. In group 1, ROSC rates were significantly lower compared to patients in group 2 (12.4% vs. 21.3% p < .001). Group 1 had 12.4% shockable rhythms vs. 17.1% in group 2 (DA-CPR and team CPR). Of the total 369 shockable cases, 42.3% (156) achieved ROSC, in the non-shockable rhythms only 14.8% achieved ROSC.ConclusionsOHCA victims receiving dispatcher assisted bystander CPR have higher rates of ROSC and more prevalence of shockable rhythms. MDA dispatchers offer DA-CPR and it is accepted 76.5% of the time. MDA patients receiving DA-CPR had higher ROSC rates and more shockable rhythms. MDA's age demographic is high, possibly affecting ROSC and shockable rhythm rates.     

Zone 3 REBOA does not provide hemodynamic benefits during nontraumatic cardiac arrest

BackgroundResuscitative endovascular balloon occlusion of the aorta (REBOA) may be a novel intervention to improve cardiopulmonary resuscitation (CPR) quality during cardiac arrest. Zone 1 supraceliac aortic occlusion improves coronary and cerebral blood flow. It is unknown if Zone 3 occlusion distal to the renal arteries offers a similar physiologic benefit while maintaining blood flow to organs above the point of occlusion.MethodsFifteen swine were anesthetized, instrumented, and placed into ventricular fibrillation. Mechanical CPR was immediately initiated. After 5 min of CPR, Zone 1 REBOA, Zone 3 REBOA, or no intervention (control) was initiated. Hemodynamic variables were continuously recorded for 30 min.ResultsThere were no significant differences between groups before REBOA deployment. Once REBOA was deployed, Zone 1 animals had statistically greater diastolic blood pressure compared to control (median [IQR]: 19.9 mmHg [9.5–20.5] vs 3.9 mmHg [2.4–4.8], p = .006). There were no differences in diastolic blood pressure between Zone 1 and Zone 3 (8.6 mmHg [5.1–13.1], p = .10) or between Zone 3 and control (p = .10). There were no significant differences in systolic blood pressure, cerebral blood flow, or time to return of spontaneous circulation (ROSC) between groups.ConclusionIn our swine model of cardiac arrest, Zone 1 REBOA improved diastolic blood pressure when compared to control. Zone 3 does not offer a hemodynamic benefit when compared to no occlusion. Unlike prior studies, immediate use of REBOA after arrest did not result in an increase in ROSC rate, suggesting REBOA may be more beneficial in patients with prolonged no-flow time.Institutional protocol numberFDG20180024A     

What is the optimal dose of epinephrine during cardiopulmonary resuscitation in a rat model?

Objective

Because different species may require different doses of drug to produce the same physiologic response, we were provoked to evaluate the dose-response of epinephrine during cardiopulmonary resuscitation (CPR) and identify what is the optimal dose of epinephrine in a rat cardiac arrest model.

Methods

Rat cardiac arrest was induced via asphyxia, and then the effects of different doses of epinephrine (0.04, 0.2, and 0.4 mg/kg IV, respectively) and saline on the outcome of CPR were compared (n = 10/each group). The primary outcome measure was restoration of spontaneous circulation (ROSC), and the secondary was the change of spontaneous respiration and hemodynamics after ROSC.

Results

Rates of ROSC were 9 of 10, 8 of 10, 7 of 10, and 1 of 10 in the low-dose, medium-dose, and high-dose epinephrine groups and saline group, respectively. The rates of withdrawal from the ventilator within 60 minutes in the low-dose (7 of 9) and medium-dose epinephrine groups (7 of 8) were higher than in the high-dose epinephrine group (1 of 7, P < .05). Mean arterial pressures were comparable, but the heart rate in the high-dose epinephrine group was the lowest among epinephrine groups after ROSC. These differences in part of time points reached statistical significance (P < .05).

Conclusion

Different doses of epinephrine produced the similar rate of ROSC, but high-dose epinephrine inhibited the recovery of spontaneous ventilation and caused relative bradycardia after CPR in an asphyxial rat model. Therefore, low and medium doses of epinephrine were more optimal for CPR in a rat asphyxial cardiac arrest model.     

Relationship between Time-to-ROSC and Survival in Out-of-hospital Cardiac Arrest ECPR Candidates: When is the Best Time to Consider Transport to Hospital?

Objective: Extracorporeal cardiopulmonary resuscitation (ECPR) may improve outcomes for refractory out-of-hospital cardiac arrest (OHCA). Transport of intra-arrest patients to hospital however, may decrease CPR quality, potentially reducing survival for those who would have achieved return-of-spontaneous-circulation (ROSC) with further on-scene resuscitation. We examined time-to-ROSC and patient outcomes for the optimal time to consider transport. Methods: From a prospective registry of consecutive adult non-traumatic OHCA's, we identified a hypothetical ECPR-eligible cohort of EMS-treated patients with age ≤ 65, witnessed arrest, and bystander CPR or EMS arrival < 10 minutes. We assessed the relationship between time-to-ROSC and survival, and constructed a ROC curve to illustrate the ability of a pulseless state to predict non-survival with conventional resuscitation. Results: Of 6,571 EMS-treated cases, 1,206 were included with 27% surviving. Increasing time–to–ROSC (per minute) was negatively associated with survival (adjusted OR 0.91; 95%CI 0.89–0.93%). The yield of survivors per minute of resuscitation increased from commencement and started to decline in the 8th minute. Fifty percent and 90% of survivors had achieved ROSC by 8.0 and 24 min, respectively, at which times the probability of survival for those with initial shockable rhythms was 31% and 10%, and for non-shockable rhythms was 5.2% and 1.6%. The ROC curve illustrated that the 16th minute of resuscitation maximized sensitivity and specificity (AUC = 0.87, 95% CI 0.85–0.89). Conclusion: Transport for ECPR should be considered between 8 to 24 minutes of professional on-scene resuscitation, with 16 minutes balancing the risks and benefits of early and later transport. Earlier transport within this window may be preferred if high quality CPR can be maintained during transport and for those with initial non-shockable rhythms.     

Pentoxifylline improves circulatory and metabolic recovery after cardiopulmonary resuscitation

BACKGROUND: To evaluate the effectiveness of a bolus application of pentoxifylline (PTXF) at the beginning of CPR in a standardized resuscitation animal model. METHODS AND RESULTS: In a laboratory model of cardiac arrest, 12 Wistar rats (382-413 g) were randomized into two groups. Both groups underwent 4 min of cardiopulmonary arrest induced by a transthoracic application of a fibrillating current of 10 mA. At the beginning of CPR, group one (n=6) received a bolus injection of 10 mg kg(-1) body weight PTXF versus sodium chloride in group two (controls: n=6). All animals developed a severe lactate acidosis during and after CPR but in PTXF treated animals acid-base values returned to baseline pattern. During return of spontaneous circulation (ROSC) in the PTXF group lactate concentration decreased from 13.4+/-2.1 to 1.9+/-0.7 mmol l(-1) within 60 min (P<0.01). In control animals, lactate values remained high (10.8+/-3.5 by 60 min, P<0.01). After bolus injection of PTXF pH increased from 6.93+/-0.06 to 7.29+/-0.13 within 60 min of ROSC versus 6.85+/-0.05 to 6.97+/-0.23 in sodium chloride treated animals (P<0.01). Within 5 min of ROSC, PTXF treated animals achieved higher oxygenation values (PTXF P(a)O(2)=216.9+/-62.5 mmHg, control 132. 2+/-15.1 mmHg, P<0.01). CONCLUSIONS: Administration of PTXF at the beginning of CPR improved macrocirculation, acid-base status and arterial oxygenation.     

Chest compression quality management and return of spontaneous circulation: A matched-pair registry study

Aims

Investigating the effects of any intervention during cardiac arrest remains difficult. The ROSC after cardiac arrest score was introduced to facilitate comparison of rates of return of spontaneous circulation (ROSC) between different ambulance services. To study the influence of chest compression quality management (including training, real-time feedback devices, and debriefing) in comparison with conventional cardiopulmonary resuscitation (CPR), a matched-pair analysis was conducted using data from the German Resuscitation Registry, with the calculated ROSC after cardiac arrest score as the baseline.

Methods and results

Matching for independent ROSC after cardiac arrest score variables yielded 319 matched cases from the study period (January 2007–March 2011). The score predicted a 45% ROSC rate for the matched pairs. The observed ROSC increased significantly with chest compression quality management, to 52% (P = 0.013; 95% CI, 46–57%). No significant differences were seen in the conventional CPR group (47%; 95% CI, 42–53%). The difference between the observed ROSC rates was not statistically significant.

Conclusions

Chest compression quality management leads to significantly higher ROSC rates than those predicted by the prognostic score (ROSC after cardiac arrest score). Matched-pair analysis shows that with conventional CPR, the observed ROSC rate was not significantly different from the predicted rate. Analysis shows a trend toward a higher ROSC rate for chest compression quality management in comparison with conventional CPR. It is unclear whether a single aspect of chest compression quality management or the combination of training, real-time feedback, and debriefing contributed to this result.     

Outcomes from low versus high-flow cardiopulmonary resuscitation in a swine model of cardiac arrest

Background

Return of spontaneous circulation (ROSC) is improved by greater vital organ blood flow during cardiopulmonary resuscitation (CPR). We tested the hypothesis that myocardial flow above the threshold needed for ROSC may be associated with greater vital organ injury and worse outcome.

Methods

Aortic and right atrial pressures were measured with micromanometers in 27 swine. After 10 minutes of untreated ventricular fibrillation, chest compression was performed with an automatic, load-distributing band. Animals were randomly assigned to receive flows just sufficient for ROSC (low flow: target coronary perfusion pressure = 12 mm Hg) or well above the minimally effective level (high flow: coronary perfusion pressure = 30 mm Hg). Myocardial flow was measured with microspheres, defibrillation was performed after 3.5 minutes of CPR, and ejection fraction was measured with echocardiography.

Results

Return of spontaneous circulation was achieved by 9 of 9 animals in the high-flow group and 15 of 18 in the low-flow group. All animals in the high-flow group defibrillated initially into a perfusing rhythm, whereas 12 of 15 animals achieving ROSC in the low-flow group defibrillated initially into pulseless electrical activity (P < .05, Fisher exact test). Compared with animals in the low-flow group, animals in the high-flow group had shorter resuscitation times, higher mean aortic pressures at ROSC, and higher ejection fractions at 2 hours post-ROSC (all P < .05).

Conclusion

High-flow CPR significantly improved arrest hemodynamics, rates of ROSC, and post-ROSC indicators of myocardial status, all indicating less injury with higher flows. No evidence of organ injury from vital organ blood flow substantially above the threshold for ROSC was found.     

Partial pressure of end-tidal carbon dioxide successful predicts cardiopulmonary resuscitation in the field: a prospective observational study

Introduction

Prognosis in patients suffering out-of-hospital cardiac arrest is poor. Higher survival rates have been observed only in patients with ventricular fibrillation who were fortunate enough to have basic and advanced life support initiated soon after cardiac arrest. An ability to predict cardiac arrest outcomes would be useful for resuscitation. Changes in expired end-tidal carbon dioxide levels during cardiopulmonary resuscitation (CPR) may be a useful, noninvasive predictor of successful resuscitation and survival from cardiac arrest, and could help in determining when to cease CPR efforts.

Methods

This is a prospective, observational study of 737 cases of out-of-hospital cardiac arrest. The patients were intubated and measurements of end-tidal carbon dioxide taken. Data according to the Utstein criteria, demographic information, medical data, and partial pressure of end-tidal carbon dioxide (Pet CO ₂) values were collected for each patient in cardiac arrest by the emergency physician. We hypothesized that an end-tidal carbon dioxide level of 1.9 kPa (14.3 mmHg) or more after 20 minutes of standard advanced cardiac life support would predict restoration of spontaneous circulation (ROSC).

Results

Pet CO ₂ after 20 minutes of advanced life support averaged 0.92 ± 0.29 kPa (6.9 ± 2.2 mmHg) in patients who did not have ROSC and 4.36 ± 1.11 kPa (32.8 ± 9.1 mmHg) in those who did (P < 0.001). End-tidal carbon dioxide values of 1.9 kPa (14.3 mmHg) or less discriminated between the 402 patients with ROSC and 335 patients without. When a 20-minute end-tidal carbon dioxide value of 1.9 kPa (14.3 mmHg) or less was used as a screening test to predict ROSC, the sensitivity, specificity, positive predictive value, and negative predictive value were all 100%.

Conclusions

End-tidal carbon dioxide levels of more than 1.9 kPa (14.3 mmHg) after 20 minutes may be used to predict ROSC with accuracy. End-tidal carbon dioxide levels should be monitored during CPR and considered a useful prognostic value for determining the outcome of resuscitative efforts and when to cease CPR in the field.     

Continuous Quality Improvement Efforts Increase Survival with Favorable Neurologic Outcome after Out-of-hospital Cardiac Arrest

Objective: To assess system-wide implementation of specific therapies focused on perfusion during cardiopulmonary resuscitation (CPR) and cerebral recovery after Return of Spontaneous Circulation (ROSC). Methods: Before and after retrospective analysis of an out-of-hospital cardiac arrest database. Implementation trial in the urban/suburban community of Alameda County, California, USA, population 1.6 million, from November 2009–December 2012. Adult patients with non-traumatic out-of-hospital cardiac arrest (OHCA) who received CPR and/or defibrillation. The impedance threshold device was used throughout this study and there was an increased use of mechanical CPR (mCPR) and in-hospital therapeutic hypothermia (HTH). Results: Rates of ROSC, survival to hospital discharge and Cerebral Performance Category (CPC) scores were compared using univariate and multivariable analyses. A total of 2,926 adult non-traumatic patients with OHCA received CPR during the study period. From 2009–2011 to 2012, there was an increase in ROSC from 29.0% to 34.4% (p = 0.003) and a non-significant increase in hospital discharge from 10.2% to 12.0% (p = 0.16). There was a 76% relative increase in survival with favorable neurologic function between the two periods, as determined by CPC ≤ 2, from 4.5% to 7.9% (unadjusted OR = 1.80; CI = 1.31, 2.48; p < 0.001). After adjusting for witnessed arrest, bystander CPR, initial rhythm (VT/VF vs. others), placement of an advanced airway, EMS response time, drugs administered, and age, the OR was 1.61 (1.10, 2.36; p = 0.015). Using a stepwise multivariable logistic regression model, the independent predictors of CPC ≤ 2 were 2012 (vs. 2009–2011; p = 0.022), witnessed arrest (p < 0.001), initial rhythm VT/VF (p < 0.001), and advanced airway (inverse association p < 0.001). Additional analyses of the three prescribed therapies, separately and in combination, demonstrated that for those patients admitted to the hospital, mCPR with HTH had the biggest impact on survival to hospital discharge with CPC ≤ 2. Conclusions: Specific therapies within a system of care (mCPR, HTH), developed to enhance circulation during CPR and cerebral recovery after ROSC, significantly improved survival by 74% with favorable neurologic function following OHCA.