Swine Model Of Ventricular Fibrillation Research Articles

402 Amplitude spectral area (AMSA) variations in a swine model of ventricular fibrillation: Effect of coronary occlusions

402 Amplitude spectral area (AMSA) variations in a swine model of ventricular fibrillation: Effect of coronary occlusions

Stress hormones kinetics in ventricular fibrillation cardiac arrest and resuscitation: Translational and therapeutic implications.

Knowing the kinetics of endogenous stress hormones during cardiac arrest and cardiopulmonary resuscitation (CRP) will help to optimize personalized physiology-guided treatment. The aim of this study was to examine the dynamic changes in stress hormones in a swine model of ventricular fibrillation (VF) cardiac arrest. Ventricular fibrillation was induced in 10 healthy Landrace/Large White piglets, which were subsequently left untreated for 8 min. All animals were resuscitated according to the 2015 European Resuscitation Council guidelines. The concentration of adrenalin, noradrenalin, and cortisol was measured at baseline and at the 4th and 8th minute of VF-cardiac arrest, as well as at 30-min, 60-min, 24 h and 48 h post-ROSC. By the end of the 4th min of VF, the animals of the ROSC group exhibited significantly higher adrenaline levels compared to those of the no-ROSC group (7264 pg/ml vs. 1648 pg/ml, p = 0.03). Noradrenaline was higher in the ROSC group at the 4th min of VF (3021 pg/ml vs. 1626 pg/ml, p = 0.02). Cortisol levels in the ROSC group were significantly lower by the end of the 8th min of VF [16.25 ng/ml vs. 92.82 ng/ml, p = 0.03]. With a cut-off point of 5970 pg/ml, adrenaline at the 4th min of VF exhibited 100% sensitivity and 80% specificity for predicting ROSC. Higher endogenous adrenaline and lower endogenous cortisol levels were associated with ROSC.

Abstract 10911: Amplitude Spectral Area to Guide Shock and Epinephrine Delivery in a Swine Model of Ventricular Fibrillation and Closed-Chest Resuscitation

Introduction: VF accounts for ~30% of all sudden cardiac arrest episodes. VF signal analysis in the frequency domain - calculating the amplitude spectral area (AMSA) - can inform on the probability that an electrical shock could terminate VF followed by return of spontaneous circulation (ROSC). BLS guidelines require delivery of shocks every 2 min and epinephrine every 4 min. Yet, shocks often do not terminate VF and may injure the myocardium. We have previously reported that guiding the timing of shock delivery based on AMSA reduces myocardial injury and improves outcome. Epinephrine is given to increase the coronary perfusion pressure (CPP) and therefore myocardial blood flow but has detrimental effects on post-resuscitation myocardial function and possibly on neurological outcome. Hypothesis: Monitoring AMSA during CPR could be used not only to guide shock delivery but also to avoid administering epinephrine when AMSA predicts a high probability of shock success, reserving epinephrine when AMSA predicts a low probability of shock success and additional CPP increase might be helpful. Methods: In a swine model of electrically induced VF and mechanical chest compressions, two resuscitation protocols were compared in 8 pigs each: (1) A guidelines-driven (GD), delivering shocks and epinephrine guided by the current BLS protocol and (2) An AMSA-driven, delivering shocks and epinephrine guided by AMSA (ADSE). VF was untreated for 10 min and pigs that achieved ROSC were monitored for 240 min. Results: Compared to GD, ADSE was associated with a shorter time to ROSC (400±80 vs 569±16 sec, p=0.034) and higher survival rate at 240 minutes with borderline statistical significance (7/8 vs 3/8, p=0.059). ADSE required fewer shocks (3±2 vs 5±2, p=0.026) and received fewer doses of epinephrine (median [interquartile range], 1[1-1] vs 2[1.3-3], p=0.038). Conclusions: Resuscitation with the ADSE protocol was superior to the GD protocol resulting in a shorter time to ROSC with improved survival requiring fewer shocks and fewer epinephrine doses. The ADSE protocol represents a more tailored approach to resuscitation enabling delivery of resuscitation interventions with higher precision and consequently minimizing their associated adverse effects.

Targeted Delivery of Electrical Shocks and Epinephrine, Guided by Ventricular Fibrillation Amplitude Spectral Area, Reduces Electrical and Adrenergic Myocardial Burden, Improving Survival in Swine.

BackgroundWe previously reported that resuscitation delivering electrical shocks guided by real‐time ventricular fibrillation amplitude spectral area (AMSA) enabled return of spontaneous circulation (ROSC) with fewer shocks, resulting in less myocardial dysfunction. We now hypothesized that AMSA could also guide delivery of epinephrine, expecting further outcome improvement consequent to less electrical and adrenergic burdens.Methods and ResultsA swine model of ventricular fibrillation was used to compare after 10 minutes of untreated ventricular fibrillation a guidelines‐driven (n=8) resuscitation protocol, delivering shocks every 2 minutes and epinephrine every 4 minutes, with an AMSA‐driven shocks (n=8) protocol, delivering epinephrine every 4 minutes, and with an AMSA‐driven shocks and epinephrine (ADSE; n=8) protocol. For guidelines‐driven, AMSA‐driven shocks, and ADSE protocols, the time to ROSC (mean±SD) was 569±164, 410±111, and 400±80 seconds (P=0.045); the number of shocks (mean±SD) was 5±2, 3±1, and 3±2 (P=0.024) with ADSE fewer than guidelines‐driven (P=0.03); and the doses of epinephrine (median [interquartile range]) were 2.0 (1.3–3.0), 1.0 (1.0–2.8), and 1.0 (0.3–3.0) (P=0.419). The ROSC rate was similar, yet survival after ROSC favored AMSA‐driven protocols (guidelines‐driven, 3/6; AMSA‐driven shocks, 6/6; and ADSE, 7/7; P=0.019 by log‐rank test). Left ventricular function and survival after ROSC correlated inversely with electrical burden (ie, cumulative unsuccessful shocks, J/kg; P=0.020 and P=0.046) and adrenergic burden (ie, total epinephrine doses, mg/kg; P=0.042 and P=0.002).ConclusionsDespite similar ROSC rates achieved with all 3 protocols, AMSA‐driven shocks and ADSE resulted in less postresuscitation myocardial dysfunction and better survival, attributed to attaining ROSC with less electrical and adrenergic myocardial burdens.

Prediction of cerebral perfusion pressure during CPR using electroencephalogram in a swine model of ventricular fibrillation.

Measuring the quality of cardiopulmonary resuscitation (CPR) is important for improving outcomes in cardiac arrest. Cerebral perfusion pressure (CePP) could represent cerebral circulation during CPR, but it is difficult to measure non-invasively. In this study, we developed the electroencephalogram (EEG) based brain index (EBRI) derived from EEG signals by machine learning techniques, which could estimate CePP accurately in a porcine cardiac arrest model. We conducted a randomised crossover study using nine female pigs. After 1min of untreated ventricular fibrillation, we performed CPR with 12 different 2-min tilting angle sessions, including two different head-up tilt (HUT) angles (30°, 15°) twice, horizontal angle (0°) four times and two different head-down tilt (HDT) angles (-15°, -30°) twice with the random order. We collected EEG signals using a single channel EEG electrode in real-time during CPR. We derived the EBRI models to predict the CePP classified by the 5 or 10 groups using three different machine learning algorithms, including the support vector machine (SVM), k-nearest neighbour (KNN) and random forest classification (RFC) method. We assessed the accuracy, sensitivity and specificity of each model. The accuracy of the EBRI model using an SVM algorithm in the 5-group CePP classification was 0.935 with a standard deviation (SD) from 0.923 to 0.946. The accuracy in the 10-group classification was 0.904 (SD: 0.896, 0.913). The accuracy of the EBRI using the KNN method in the 5-group classification was 0.927 (SD: 0.920, 0933) and in the 10-group was 0.894 (SD: 0.880, 0.907). The accuracy of the RFC algorithm was 0.947 (SD: 0.931, 0.963) in the 5-group classification and 0.920 (SD: 0.911, 0.929) in the 10-group classification. We developed the EBRI model using non-invasive acquisition of EEG signals to predict CePP during CPR. The accuracy the EBRI model was 0.935, 0.927 and 0.947 for each machine learning algorithm, and the EBRI could be used as a surrogate indicator for measuring cerebral perfusion during CPR.

Effect of the Abdominal Aortic and Junctional Tourniquet on chest compressions in a swine model of ventricular fibrillation.

Mortality for out-of-hospital cardiac arrest is high when traditional chest compressions are used without adjuncts. The abdominal aortic and junctional tourniquet (AAJT) is a device with a wedge-shaped air bladder that occludes the aortic bifurcation, augmenting blood flow to the heart and brain. Previously, the addition of AAJT during chest compression led to an increase in rate of survival in a model of traumatic cardiac arrest. This study was designed to determine if application of the AAJT would lead to more effective chest compressions as measured by improved hemodynamic parameters and an increased rate of return of spontaneous circulation (ROSC). Yorkshire swine (n=6 per group) underwent general anesthesia and instrumentation. Ventricular fibrillation (Vfib) was electrically induced and animals were allocated into groups with or without the AAJT. The AAJT was inflated if selected after four minutes of compressions. Following a total of ten minutes of compressions, the animals entered into a ten-minute advanced cardiac life support phase. Hemodynamics and blood gas measurements were compared between groups. ROSC or cardioversion from Vfib was not achieved in either group. The AAJT group had improved hemodynamic parameters with significantly higher carotid diastolic pressure and higher blood flow in the carotid artery (p=0.016 and 0.028 respectively). However, no significant differences were observed with coronary perfusion pressure or end tidal CO2. The AAJT did not confer a survival advantage during chest compressions, but hemodynamic improvements were observed while the AAJT was in place.

Consistent head up cardiopulmonary resuscitation haemodynamics are observed across porcine and human cadaver translational models

AimThe objectives were: 1) replicate key elements of Head Up (HUP) cardiopulmonary resuscitation (CPR) physiology in a traditional swine model of ventricular fibrillation (VF), 2) compare HUP CPR physiology in pig cadavers (PC) to the VF model 3) develop a new human cadaver (HC) CPR model, and 4) assess HUP CPR in HC. MethodsNine female pigs were intubated, and anesthetized. Venous, arterial, and intracranial access were obtained. After 6 min of VF, CPR was performed for 2 min epochs as follows: Standard (S)-CPR supine (SUP), Active compression decompression (ACD) CPR + impedance threshold device (ITD-16) CPR SUP, then ACD + ITD HUP CPR. The same sequence was performed in PC 3 h later. In 9 HC, similar vascular and intracranial access were obtained and CPR performed for 1 min epochs using the same sequence as above. ResultsThe mean cerebral perfusion pressure (CerPP, mmHg) was 14.5 ± 6 for ACD + ITD SUP and 28.7 ± 10 for ACD + ITD HUP (p = .007) in VF, −3.6 ± 5 for ACD + ITD SUP and 7.8 ± 9 for ACD + ITD HUP (p = .007) in PC, and 1.3 ± 4 for ACD + ITD SUP and 11.3 ± 5 for ACD + ITD HUP (p = .007) in HC. Mean systolic and diastolic intracranial pressures (ICP) (mmHg) were significantly lower in the ACD + ITD HUP group versus the ACD + ITD SUP group in all three CPR models. ConclusionHUP CPR decreased ICP while increasing CerPP in pigs in VF as well as in PC and HC CPR models. This first-time demonstration of HUP CPR physiology in humans provides important implications for future resuscitation research and treatment.

Sternal Route More Effective than Tibial Route for Intraosseous Amiodarone Administration in a Swine Model of Ventricular Fibrillation

Objective: The pharmacokinetics of IO administered lipid soluble amiodarone during ventricular fibrillation (VF) with ongoing CPR are unknown. This study measured mean plasma concentration over 5 minutes, maximum plasma concentration (Cmax), and time to maximum concentration (Tmax) of amiodarone administered by the sternal IO (SIO), tibial IO (TIO), and IV routes in a swine model of VF with ongoing CPR. Methods: Twenty-one Yorkshire-cross swine were randomly assigned to three groups: SIO, TIO, and IV. Ventricular fibrillation was induced under general anesthesia. After 4 minutes in VF, 300 mg amiodarone was administered as indicated by group assignment. Serial blood specimens collected at 30, 60, 90, 120, 150, 180, 240, and 300 seconds were analyzed using high performance liquid chromatography with tandem mass spectrometry. Results: The mean plasma concentration of IV amiodarone over 5 minutes was significantly higher than the TIO group at 60 seconds (P = 0.02) and 90 seconds (P = 0.017) post-injection. No significant differences in Cmax between the groups were found (P <0.05). The Tmax of amiodarone was significantly shorter in the SIO (99 secs) and IV (86 secs) groups compared to the TIO group (215 secs); P = 0.002 and P = 0.002, respectively. Conclusions: The SIO and IV routes of amiodarone administration were comparable. The TIO group took nearly three times longer to reach Tmax than the SIO and IV groups, likely indicating depot of lipid-soluble amiodarone in adipose-rich tibial yellow bone marrow. The SIO route was more effective than the TIO route for amiodarone delivery in a swine model of VF with ongoing CPR. Further investigations are necessary to determine if the kinetic differences found between the SIO and TIO routes in this study affect survival of VF in humans.

The Resuscitative and Pharmacokinetic Effects of Humeral Intraosseous Vasopressin in a Swine Model of Ventricular Fibrillation.

Twenty-seven Yorkshire-cross swine (60 to 80 kg) were assigned randomly to three groups: HIO (n=9), IV (n=9), and a control group (n=9). Ventricular fibrillation was induced and untreated for two minutes. Chest compressions began at two minutes post-arrest and vasopressin (40 U) administered at four minutes post-arrest. Serial blood specimens were collected for four minutes, then the swine were resuscitated until ROSC or 29 post-arrest minutes elapsed. Fisher's Exact test determined ROSC was significantly higher in the HIO 5/7 (71.5%) and IV 8/11 (72.7%) groups compared to the control 0/9 (0.0%; P=.001). Odds ratios of ROSC indicated no significant difference between the treatment groups (P=.68) but significant differences between the HIO and control, and the IV and control groups (P=.03 and .01, respectively). Analysis of Variance (ANOVA) indicated the mean time to ROSC for HIO and IV was 621.20 seconds (SD=204.21 seconds) and 554.50 seconds (SD=213.96 seconds), respectively, with no significant difference between the groups (U=11; P=.22). Multivariate Analysis of Variance (MANOVA) revealed the maximum plasma concentration (Cmax) and time to maximum concentration (Tmax) of vasopressin in the HIO and IV groups was 71753.9 pg/mL (SD=26744.58 pg/mL) and 61853.7 pg/mL (SD=22745.04 pg/mL); 111.42 seconds (SD=51.3 seconds) and 114.55 seconds (SD=55.02 seconds), respectively. Repeated measures ANOVA indicated no significant difference in plasma vasopressin concentrations between the treatment groups over four minutes (P=.48). The HIO route delivered vasopressin effectively in a swine model of VF. Occurrence, time, and odds of ROSC, as well as pharmacokinetic measurements of HIO vasopressin, were comparable to IV. Burgert JM , Johnson AD , Garcia-Blanco J , Fulton LV , Loughren MJ . The resuscitative and pharmacokinetic effects of humeral intraosseous vasopressin in a swine model of ventricular fibrillation. Prehosp Disaster Med. 2017;32(3):305-310.

The influence of sildenafil on myocardial catecholamine level in a swine model of ventricular fibrillation

Objective To reveal the changes of catecholamine and lactate levels in myocardial interstitial fluid during cardiopulmonary resuscitation in order to prove the protective effects of sildenafil pretreatment on post-resuscitation myocardial function in swine model of ventricular fibrillation(VF). Methods Twenty-four swine were randomly(random number) divided into three groups: saline group, sildenafil group and shame operation group. Sildenafil in dose of 0.5 mg/kg dissolved in 40 mL of saline was given to swine once intraperitoneally 40 min prior to VF in sildenafil group.The equivalent volume of saline (0.9% NaCl) alone was administered instead in saline groups. There was no treatment in shame operation group. After ventricular fibrillation untreated for 8 min, open-chest cardiopulmonary resuscitation was initiated. The hemodynamic variables were recorded at baseline, 4 min, 1 h and 6 h after restoration of spontaneous circulation(ROSC). The interstitial fluid from the left ventricle wall was collected by using the microdialysis tubes at given intervals, in which the levels of dopamine, norepinephrine, epinephrine, and lactate were measured. The samples for pathological examination were taken at 24 hours after ROSC. Results The levels of catecholamine and lactate in the sildenafil group were lower than those in saline group at all different intervals(P<0.05 or P<0.01). The cumulative defibrillation energy was lower in the sildenafil group than that in the saline group(P<0.05). The hemodynamic changes and myocardial histological damage in sildenafil group were milder than those in saline group(P<0.05). The pathologic changes of myocardium and mitochondria in saline group were more severe than those in sildenafil group. Conclusions Sildenafil pretreatment prior to VF can effectively reduce endogenous catecholamine secretion and lactate levels in myocardial tissue, protecting the myocardium and improving post-resuscitation myocardial function. Key words: Sildenafil; Cardiopulmonary resuscitation; Microdialysis; Catecholamine; Lactate; Hemodynamics

Centhaquin Effects in a Swine Model of Ventricular Fibrillation: Centhaquin and Cardiac Arrest.

Centhaquin citrate is a novel agent being developed for use in the treatment of haemorrhagic shock. The aim of our study was to assess whether the administration of centhaquin would improve initial resuscitation success, 24-hour survival, and neurologic outcome compared with adrenaline alone in a porcine model of ventricular fibrillation. Ventricular fibrillation was induced in 20 healthy Landrace/Large White piglets. The animals were randomised to receive placebo plus adrenaline 0.02mg/kg (n=10, Group C) and adrenaline 0.02mg/kg plus centhaquin 0.015mg/kg (n=10, Group S). All animals were resuscitated according to the 2010 European Resuscitation Council guidelines. Haemodynamic variables were measured before arrest, during arrest and resuscitation, and during the first two hours after return of spontaneous circulation (ROSC). Survival and a neurologic alertness score were measured at 24hours after ROSC. A significant difference was observed in ROSC rate between the two groups, as 10 animals (100%) from Group S and 4 animals (40%) from Group C achieved ROSC (p=0.011). Systolic, diastolic, and mean aortic pressure and coronary perfusion pressure were significantly higher in Group S at the end of the second cycle of CPR. In our study, all subjects with ROSC survived for 24hours, while we observed no statistically significant differences in neurologic examination (Group C 100±0, Group S 96±12.64; p=0.527). The addition of centhaquin to adrenaline improved ROSC rates in a swine model of VF cardiac arrest.

High Serum Tumor Necrosis Factor Levels in the Early Post-Cardiac Arrest Period Are Associated with Poor Short-Term Survival in a Swine Model of Ventricular Fibrillation.

Most resuscitated victims of out-of-hospital cardiac arrest who survive to hospital expire due to the postresuscitation syndrome. This syndrome is characterized by a sepsis-like proinflammatory state. The objective of this investigation was to determine whether a relationship exists between the rise of tumor necrosis factor (TNF), a proinflammatory cytokine, following return of spontaneous circulation (ROSC), and early postarrest survival in a clinically relevant animal model of spontaneous ventricular fibrillation (VF). Mixed-breed Yorkshire swine (n = 20), weighing 39 ± 5 kg, were anesthetized and catheters placed in the right atrium and left ventricle/ascending aorta for continuous pressure monitoring. VF was induced by occluding the left anterior descending coronary artery with an angioplasty balloon. After 7 min of untreated VF, advanced life support resuscitation attempts were made for up to 20 min. Animals achieving ROSC were monitored for 3 h and fluid and pressor support was administered as needed. TNF levels were measured before VF and at 0, 15, and 30 min after ROSC using quantitative sandwich enzyme-linked immunosorbent assay. Twelve (60%) animals experienced early death, expiring during the 3 hour postarrest period (9 pulseless electrical activity, 2 VF, and 1 asystole). The TNF level at 15 min post-ROSC was significantly associated with death within the first 3 h post-ROSC with a univariate odds ratio of 1.4 [95% confidence interval (CI) 1.05-2.2, P = 0.01]. Using a cutoff TNF level of 525 pg/mL at 15 min post-ROSC had 100% negative predictive value (95% CI 0%-37%) and 67% positive predictive value (95% CI 35%-90%) for early death with a hazard ratio of 6.6 (95% CI 1.9-23.5). TNF increases shortly after ROSC and is predictive of early death. Early identification of resuscitated victims at greatest risk for hemodynamic collapse and recurrent arrest might facilitate the use of early hospital-based interventions to decrease the likelihood of a poor outcome.

Combination of chest compressions and interposed abdominal compressions in a swine model of ventricular fibrillation

PurposeThe aim of this study was to investigate the effects of the combination of chest compressions and interposed abdominal compressions (IAC-CPR) in a swine model of ventricular fibrillation (VF). MethodsTwenty healthy female Landrace-Large White pigs were the study subjects. At the end of the eighth minute of VF, animals in the control group (Group A) received chest compressions at a rate of 100/min, while animals in the experimental group received chest compressions and simultaneous interposed abdominal compressions (CC-IAC – Group B), both at a rate of 100/min. The primary end point of the experiment was return of spontaneous circulation (ROSC). Secondary outcomes were 48-h survival rate and 48-h neurologic outcome. ResultsSix animals (60%) from Group A and 9 animals (90%) from Group B achieved ROSC (P=.121). There was a statistically significant difference in systolic aortic pressure, mean aortic pressure, right atrial pressures, and end-tidal carbon dioxide (ETCO2) between the two groups during the first cycle of CPR, while during the second cycle, diastolic aortic pressure was significantly higher in Group B. Coronary perfusion pressure (CPP) values in group B were significantly higher compared with those in Group A during the first and second cycle of CPR. Neurologic examination was statistically significantly better in Group B (75.00±10.00 vs. 90.00±10.00, P=.037). ConclusionROSC did not differ statistically significant in the IAC-CPR compared to the CPR group only, while CPP was significantly higher in IAC-CPR–treated animals.

Effects of Erythropoietin Administration on Adrenal Glands of Landrace/Large White Pigs after Ventricular Fibrillation

Aim. To evaluate the effects of erythropoietin administration on the adrenal glands in a swine model of ventricular fibrillation and resuscitation. Methods. Ventricular fibrillation was induced via pacing wire forwarded into the right ventricle in 20 female Landrace/Large White pigs, allocated into 2 groups: experimental group treated with bolus dose of erythropoietin (EPO) and control group which received normal saline. Cardiopulmonary resuscitation (CPR) was performed immediately after drug administration as per the 2010 European Resuscitation Council (ERC) guidelines for Advanced Life Support (ALS) until return of spontaneous circulation (ROSC) or death. Animals who achieved ROSC were monitored, mechanically ventilated, extubated, observed, and euthanized. At necroscopy, adrenal glands samples were formalin-fixed, paraffin-embedded, and routinely processed. Sections were stained with hematoxylin-eosin. Results. Oedema and apoptosis were the most frequent histological changes and were detected in all animals in the adrenal cortex and in the medulla. Mild and focal endothelial lesions were also detected. A marked interindividual variability in the degree of the intensity of apoptosis and oedema at cortical and medullary level was observed within groups. Comparing the two groups, higher levels of pathological changes were detected in the control group. No significant difference between the two groups was observed regarding the endothelial changes. Conclusions. In animals exposed to ventricular fibrillation, EPO treatment has protective effects on the adrenal gland.

Effect of Erythropoietin on Postresuscitation Renal Function in a Swine Model of Ventricular Fibrillation.

Purpose. To investigate the effect of EPO administration on postresuscitation renal function. Methods. Twenty-four female Landrace/Large-White piglets aged 10–15 weeks with average weight of 19 ± 2 kg were randomly assigned to 2 different groups of 12 subjects each. After the end of an 8-minute ventricular fibrillation, the control group (Group C) received saline as placebo, whereas the EPO group (Group E) received EPO 5000 U/kg. The animals were resuscitated according to the 2010 European Resuscitation Council Guidelines for Resuscitation. Results. Five animals (41.67%) from Group C and 11 animals (91.67%) from Group E achieved ROSC (p = 0.027). Eight animals (66.67%, 5 surviving and 3 nonsurviving) from Group C suffered severe kidney damage or AKI compared to animals from Group E, in which none of the swine had evidence of severe kidney damage or AKI (p = 0.001). There was a statistically significant difference in all tested biochemical markers between the two groups, as well as a positive correlation of creatinine with NGAL, L-FABP, and IL-18 (summed mean values' p = 0.049, 0.01, and 0.004, resp.). Conclusions. Administration of EPO protected swine from postresuscitation acute kidney injury.

The effects of proximal and distal routes of intraosseous epinephrine administration on short-term resuscitative outcome measures in an adult swine model of ventricular fibrillation: a randomized controlled study

IntroductionIt is unknown if the anatomical distance of intraosseous (IO) epinephrine injection from the heart affects resuscitative outcome. The purpose of this study was to explore the relationships between the anatomical distance of IO epinephrine injection and measures of resuscitative outcome in an adult swine model of ventricular fibrillation (VF). MethodsThirty-two Yorkshire-cross swine (60–80 kg) were randomly assigned to four groups: humeral IO (HIO), tibial IO (TIO), IV with defibrillation and epinephrine, and IV control: with defibrillation but no epinephrine. Ventricular fibrillation was induced. Swine remained in VF for 4 minutes prior to mechanical chest compressions. After 6 minutes in VF, swine were defibrillated and epinephrine (0.01 mg/kg) administered by group assignment. Defibrillation was repeated every 2 minutes. Epinephrine was repeated every 4 minutes. Interventions continued until return of spontaneous circulation (ROSC) or 26 post-arrest minutes elapsed. Swine achieving ROSC were observed for 30 minutes post-ROSC. ResultsThere were no significant differences between the HIO, TIO, and IV groups relative to the occurrence of ROSC (P > .05 in all cases), 30-minute post-ROSC survival (P > .05 in all cases), and time to ROSC (P = .43). There were significant differences between the HIO, TIO, and IV groups compared to the control group relative to the occurrence of ROSC (P = .02, .01, and .007 respectively), and 30 minute post-ROSC survival (P = .05, .03, and .007, respectively). ConclusionThe anatomical distance of IO epinephrine injection from the heart did not affect short-term measures of resuscitative outcome in an adult swine model of VF including the occurrence of ROSC, 30 minute post-ROSC survival, and time to ROSC. Rapidly administered epinephrine, irrespective of route of administration, increased the chance ROSC and survival to 30 minutes post-ROSC would occur in this study.

0391. Comparison of the histopathologic effects on the lungs of two external chest compression devices (lucas versus autopulse) in a swine model of ventricular fibrillation

Given the difficulty of performing efficient CPR compressions, technology has turned to automaticity. LUCAS device has a pneumatically driven piston to compress the heart and uses active decompression suction on the upstroke. AUTOPULSE is a load distributing band compressor, that is mechanically actuated and battery driven. It provides both direct compression and semi-circumferential thoracic compression.

Effects of mild hypothermia used for protecting neurological function on electrolytes changes in swine model of ventricular fibrillation after cardiopulmonary resuscitation

Objective To study the changes of hemodynamic parameters and electrolytes observed within 72 hours of hypothermic therapy in porcine model of cardiac ventricular fibrillation after cardiopulmonary resuscitation （CPR ） in order to provide clinical basis for safe application of mild hypothermia.Methods After typical ventricular fibrillation （VF）for 8 minutes,the survival animals were randomly （random number）divided into two groups,namely normothermia group and hypothermia group. Upon restoration of spontaneous circulation （ROSC ）,swine of the hypothermic group was treated by endovascular cooling device at a rate of 1 ℃/h until 33 ℃ and it was maintained for 12 h,then rewarming was initiated passively at a rate of 0.5 ℃/h until 38 ℃.The neurologic deficit scores （NDS）of swine were used to evaluate neurological function at 24 h and 72 h after recovery.Serum levels of potassium and sodium were measured at 0.5 h,6 h,12 h,24 h and 72 h after recovery.Results ROSC （restoration of spontaneous circulation）rate was 84.2%.The hypothermia group had higher survival rates at 24 h （75%） and 72 h （62.5%）compared to the normothermia group （37.5% and 25%,respectively）,（P〈0.01 ）. There were no significant differences in hemodynamic variables （HR,MAP,CO,PAWP and CVP）between the two groups （P〈0.05 ）,Serum potassium of the hypothermia group was lower obviously at 24 h after recovery （3.41 ±0.11）（P〈0.01）,and there were no significant differences in serum sodium at all the intervals,and there were no significant differences in underlying trend of electrolytes changes over time （P〉0.05）.The mean NDSs at 24 h and 72 h after recovery was 112.5 （98.75 -126.25）and 61 （50-75）, respectively,in the hypothermic group,and 230 （225 -235）and 207.5 （165 -250）,respectively,in the normothermia group （P 〈0.01 ）.Conclusions Hypothermia has little influence on serum levels of potassium and sodium,and mild hypothermia following resuscitation improves neurological function in the porcine models of cardiac fibrillation. Key words: Cardiopulmonary resuscitation; Ventricular fibrillation; Cardiac arrest; Hypothermia therapy; Endovascular cooling; Hemodynamic; Restoration of spontaneous circulation; Neurological Deficit score

Administration of Erythropoietin in a swine model of prolonged cardiac arrest

Purpose of the study: Recombinant human erythropoietin (rh-EPO) has been shown to exert tissue protective properties in various experimental models. However, its potential role in the cardiac arrest (CA) setting has not yet been sufficiently elucidated. The purpose of our study was to evaluate the effect of rh-EPO administration in swine model of ventricular fibrillation (VF) CA. The primary goal of our study was to investigate whether rh-EPO exerts any beneficial effect on Return of Spontaneous Circulation (ROSC) rates, while the secondary aim was to assess its impact in the short-term basis of 24-h and 48-h survival.

Abstract 73: Changes in AMSA During Controlled Coronary Perfusion by Extracorporeal Circulation in a Swine Model of Ventricular Fibrillation

Background: Previous VF studies in rats showed that 6 min of CPR was needed before an electrical shock could be successful in reestablishing cardiac activity. During this interval the amplitude spectral area (AMSA) - a method of VF waveform analysis - progressively rose reaching a plateau within the same interval required for enabling successful defibrillation. No previous studies have examined AMSA continuously using a model of tightly controlled CPR. Methods: VF was induced and left untreated for 8 min in 16 swine after which extracorporeal circulation (ECC) was maintained for 10 min adjusting its flow to generate a coronary perfusion pressure of 10 mmHg. AMSA was calculated from the VF signal in the frequency domain within 2-48 Hz and analyzed continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s. Results: AMSA progressively declined during untreated VF. During ECC, AMSA rose from 6.8±1.9 to 12.4±4.1 mV*Hz (p&lt;0.001). The increase occurred early during ECC and plateaued after 4 to 6 minutes (Figure). Individual experiments showed distinct and varying AMSA patterns during ECC. The average peak AMSA was reached 368 ± 127 s after the start of ECC. Conclusion: The time course of AMSA varied among animals suggesting variability in the time required for the myocardium to reach the optimal conditions for successful defibrillation and highlights the value of continuous monitoring of AMSA during CPR.