Evaluation of coronary blood flow velocity during cardiac arrest with circulation maintained through mechanical chest compressions in a porcine model

Intra-aortic balloon pump synchronized with chest compressions improves outcome during cardiopulmonary resuscitation in experimental cardiac arrest

BACKGROUND

Intra-aortic balloon pump (IABP) and resuscitative endovascular balloon occlusion of the aorta (REBOA) are two endovascular intervention methods for circulatory support. The aim of this study was to compare the hemodynamic effects of simultaneous mechanical chest compressions (MCC) with IABP, REBOA and those with only MCC (overall and detailed in the MCC cycle) and return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR) in experimental non-traumatic cardiac arrests (CA).

METHOD

CA was electrically induced (ventricular fibrillation) in 24 anesthetized pigs, which then were randomized to MCC synchronized IABP (n = 8), total occluded REBOA (n = 8), or control (n = 8). After 10 min of CA, CPR with MCC was started followed by one of the interventions after one minute of CPR. Every other minute after MCC start, the pigs were defibrillated with 200 J if VF/ventricular tachycardia, and after six minutes, adrenaline was administered and repeated every four minutes. The proportions of ROSC were calculated. Hemodynamic variables, including systemic blood and coronary perfusion pressures (CPP), and carotid and iliac blood flows, were collected and analyzed with 0.02 s resolution.

RESULTS

In both the IABP and REBOA groups, 7 of 8 animals (87.5 %) achieved ROSC, in contrast with 2 of 8 (25 %) in the control group (P = 0.04). IABP and REBOA significantly increased systemic arterial pressure (P = 0.002 and P = 0.015, respectively), and REBOA also increased CPP and carotid blood flow when compared to controls (P = 0.007 and P = 0.03, respectively). Animals with IABP had a preserved blood flow in the iliac artery during CPR. No differences were detected after ROSC in hemodynamic, metabolic, and organ injury variables between the REBOA and IABP groups.

CONCLUSION

Both IABP and REBOA increased the proportion of ROSC compared to controls. However, REBOA occluded distal blood flow, while IABP maintained it. This study suggests that MCC synchronized IABP could be an adjunct in the treatment of non-traumatic CA.

High central venous pressure amplitude predicts successful defibrillation in a porcine model of cardiac arrest

AIM

Increasing venous return during cardiopulmonary resuscitation (CPR) has been shown to improve hemodynamics during CPR and outcomes following cardiac arrest (CA). We hypothesized that a high central venous pressure amplitude (CVP-A), the difference between the maximum and minimum central venous pressure during chest compressions, could serve as a robust predictor of return of spontaneous circulation (ROSC) in addition to traditional measurements of coronary perfusion pressure (CPP) and end-tidal CO2 (etCO2) in a porcine model of CA.

METHODS

After 10 min of ventricular fibrillation, 9 anesthetized and intubated female pigs received mechanical chest compressions with active compression/decompression (ACD) and an impedance threshold device (ITD). CPP, CVP-A and etCO2 were measured continuously. All groups received biphasic defibrillation (200 J) at minute 4 of CPR and were classified into two groups (ROSC, NO ROSC). Mean values were analyzed over 3 min before defibrillation by repeated-measures Analysis of Variance and receiver operating characteristic (ROC).

RESULTS

Five animals out of 9 experienced ROSC. CVP-A showed a statistically significant difference (p = 0.003) between the two groups during 3 min of CPR before defibrillation compared to CPP (p = 0.056) and etCO2 (p = 0.064). Areas-under-the-curve in ROC analysis for CVP-A, CPP and etCO2 were 0.94 (95% Confidence Interval 0.86, 1.00), 0.74 (0.54, 0.95) and 0.78 (0.50, 1.00), respectively.

CONCLUSION

In our study, CVP-A was a potentially useful predictor of successful defibrillation and return of spontaneous circulation. Overall, CVP-A could serve as a marker for prediction of ROSC with increased venous return and thereby monitoring the beneficial effects of ACD and ITD.

Mathematical model of modified hybrid pump mechanism for cardiopulmonary resuscitation

BACKGROUND AND OBJECTIVE

The "Cardiac pump theory" and "Thoracic pump theory" are representative theories of cardiopulmonary resuscitation (CPR) mechanisms. Based on these theories, many studies on mathematical modeling have been performed to help understand hemodynamics during CPR. However, there are parts that do not yet properly reflect the physiology of CPR. Therefore, this study aims to develop a lumped parameter model of CPR that can more accurately reflect the current CPR physiology.

METHODS

By adding compartments of the superior and inferior vena cava of the thoracic cavity to the existing CPR model, and the "Hybrid pump" mechanism was applied to simulate CPR. To compare the hemodynamics of the conventional CPR model and the developed CPR model, various conditions, such as active compression-decompression CPR with an impedance threshold valve device (ACD-CPR+ITV), head-up-tilt (HUT), and head-down-tilt (HDT), were simulated. The coronary perfusion pressure (CPP) was compared by modulating the compression ratio of the atrium and ventricle with the thoracic pump factor.

RESULTS

The result for the comparison of coronary blood flow showed that the existing model is predominant in the compression phase, whereas the developed model is dominant in the relaxation phase. ACD-CPR + ITV results showed that the CPP decreased by 5 % in the existing model, and increased by about 46 % in the developed model, revealing a distinct hemodynamic difference between the two models. Likewise, as a result of comparing the hemodynamic differences of the two models according to the changes in tilt angle, the HUT showed similar trends, while the HDT showed slightly different results. The CPP varied accordingly with the ratio of the ventricular and atrial thoracic pump factor.

CONCLUSION

Comparison of the hemodynamics with the existing model by simulating various conditions showed that the developed CPR model reflects the CPR physiology better. The model suggests that the hemodynamics may vary depending on the ventricle and atrium compression ratio. This study may provide an important basis for helping understand various situations and patient-specific hemodynamic characteristics during CPR through in-depth research, such as patient-specific model and parameter optimization.

Corpuls CPR Generates Higher Mean Arterial Pressure Than LUCAS II in a Pig Model of Cardiac Arrest

According to the European Resuscitation Council guidelines, the use of mechanical chest compression devices is a reasonable alternative in situations where manual chest compression is impractical or compromises provider safety. The aim of this study is to compare the performance of a recently developed chest compression device (Corpuls CPR) with an established system (LUCAS II) in a pig model. Methods. Pigs (n = 5/group) in provoked ventricular fibrillation were left untreated for 5 minutes, after which 15 min of cardiopulmonary resuscitation was performed with chest compressions. After 15 min, defibrillation was performed every 2 min if necessary, and up to 3 doses of adrenaline were given. If there was no return of spontaneous circulation after 25 min, the experiment was terminated. Coronary perfusion pressure, carotid blood flow, end-expiratory CO₂, regional oxygen saturation by near infrared spectroscopy, blood gas, and local organ perfusion with fluorescent labelled microspheres were measured at baseline and during resuscitation. Results. Animals treated with Corpuls CPR had significantly higher mean arterial pressures during resuscitation, along with a detectable trend of greater carotid blood flow and organ perfusion. Conclusion. Chest compressions with the Corpuls CPR device generated significantly higher mean arterial pressures than compressions performed with the LUCAS II device.

Unexpected collateral impact after out of hospital resuscitation using LUCAS system

BACKGROUND

Mechanical chest compression using a piston device during reanimation is often the only way to ensure stable chest compression at a constant rate and force. However, its use can be associated with severe fractures of the thoracic rib cage and endanger the clinical course of the patient. Thus, the usage of such a piston device during the reanimation has currently been classified as a mere Class IIB indication.

CASE PRESENTATION

We present a case of a 66-year-old male who underwent emergent CABG surgery after receiving out-of-hospital resuscitation as a result of myocardial infarction using the LUCAS system. Due to severe bilateral rib fractures a concomitant emergency chest-wall stabilization surgery had to be performed to ensure uncompromised graft flow to obtain stable cardiac function and hemodynamics.

CONCLUSIONS

Reanimation using LUCAS-System might enable stable resuscitation conditions. However, it is crucial not to underestimate potential collateral damage which can in turn aggravate patient's clinical condition.

Cardiopulmonary resuscitation using electrically driven devices: a review

In the treatment of sudden cardiac arrest (SCA) immediate resuscitation with chest compressions and ventilation is crucial for survival. As manual resuscitation is associated with several drawbacks, mechanical resuscitation devices have been developed to support resuscitation teams. These devices are able to achieve better perfusion of heart and brain in laboratory settings, but real world experience showed no significant improved survival in comparison to manual resuscitation. This review will focus on two mechanical resuscitation devices, the Lund University Cardiac Assist System (LUCAS) and AutoPulse devices and the actual literature available. In conclusion, the general use of mechanical resuscitation devices cannot be recommended at the moment.

Quality of cardiopulmonary resuscitation in out-of-hospital cardiac arrest before and after introduction of a mechanical chest compression device, LUCAS-2; a prospective, observational study

BACKGROUND

Mechanical chest compressions have been proposed to provide high-quality cardiopulmonary resuscitation (CPR), but despite the growing use of mechanical chest compression devices, only few studies have addressed their impact on CPR quality. This study aims to evaluate mechanical chest compressions provided by LUCAS-2 (Lund University Cardiac Assist System) compared with manual chest compression in a cohort of out-of-hospital cardiac arrest (OHCA) cases.

METHODS

In this prospective study conducted in the Central Denmark Region, Denmark, the emergency medical service attempted resuscitation and reported data on 696 non-traumatic OHCA patients between April 2011 and February 2013. Of these, 155 were treated with LUCAS CPR after an episode with manual CPR. The CPR quality was evaluated using transthoracic impedance measurements collected from the LIFEPAK 12 defibrillator, and the effect was assessed in terms of chest compression rate, no-flow time and no-flow fraction; the fraction of time during resuscitation in which the patient is without spontaneous circulation receiving no chest compression.

RESULTS

The median total episode duration was 21 minutes, and the episode with LUCAS CPR was significantly longer than the manual CPR episode, 13 minutes vs. 5 minutes, p < 0.001. The no-flow fraction was significantly lower during LUCAS CPR (16%) than during manual CPR (35%); difference 19% (95% CI: 16% to 21%; p < 0.001). No differences were found in pre- and post-shock no-flow time throughout manual CPR and LUCAS CPR. Contrary to the manual CPR, the average compression rate during LUCAS CPR was in conformity with the current Guidelines for Resuscitation, 102/minute vs. 124/minute, p < 0.001.

CONCLUSION

Mechanical chest compressions provided by the LUCAS device improve CPR quality by significantly reducing the NFF and by improving the quality of chest compression compared with manual CPR during OHCA resuscitation. However, data on end-tidal Co2 and chest compression depth surrogate parameters of CPR quality could not be reported.

Repeated epinephrine doses during prolonged cardiopulmonary resuscitation have limited effects on myocardial blood flow: a randomized porcine study

Background

In current guidelines, prolonged cardiopulmonary resuscitation (CPR) mandates administration of repeated intravenous epinephrine (EPI) doses. This porcine study simulating a prolonged CPR-situation in the coronary catheterisation laboratory, explores the effect of EPI-administrations on coronary perfusion pressure (CPP), continuous coronary artery flow average peak velocity (APV) and amplitude spectrum area (AMSA).

Methods

Thirty-six pigs were randomized 1:1:1 to EPI 0.02 mg/kg/dose, EPI 0.03 mg/kg/dose or saline (control) in an experimental cardiac arrest (CA) model. During 15 minutes of mechanical chest compressions, four EPI/saline-injections were administered, and the effect on CPP, APV and AMSA were recorded. Comparisons were performed between the control and the two EPI-groups and a combination of the two EPI-groups, EPI-all.

Result

Compared to the control group, maximum peak of CPP (P_max) after injection 1 and 2 was significantly increased in the EPI-all group (p = 0.022, p = 0.016), in EPI 0.02-group after injection 2 and 3 (p = 0.023, p = 0.027) and in EPI 0.03-group after injection 1 (p = 0.013). At P_max, APV increased only after first injection in both the EPI-all and the EPI 0.03-group compared with the control group (p = 0.011, p = 0.018). There was no statistical difference of AMSA at any P_max. Seven out of 12 animals (58%) in each EPI-group versus 10 out of 12 (83%) achieved spontaneous circulation after CA.

Conclusion

In an experimental CA-CPR pig model repeated doses of intravenous EPI results in a significant increase in APV only after the first injection despite increments in CPP also during the following 2 injections indicating inappropriate changes in coronary vascular resistance during subsequent EPI administration.