Coronary blood flow and perfusion pressure during coronary angiography in patients with ongoing mechanical chest compression: A report on 6 cases

Recovery of arterial blood pressure after chest compression pauses in patients with out-of-hospital cardiac arrest

BACKGROUND AND AIMS

Chest compressions generating good perfusion during cardiopulmonary resuscitation (CPR) in cardiac arrest patients are critical for positive patient outcomes. Conventional wisdom advises minimizing compression pauses because several compressions are required to recover arterial blood pressure (ABP) back to pre-pause values. Our study examines how compression pauses influence ABP recovery post-pause in out-of-hospital cardiac arrest.

METHODS

We analyzed data from a subset of a prospective, randomized LUCAS 2 Active Decompression trial. Patients were treated by an anesthesiologist-staffed rapid response car program in Oslo, Norway (2015-2017) with mechanical chest compressions using the LUCAS device at 102 compressions/min. Patients with an ABP signal during CPR and at least one compression pause >2 sec were included. Arterial cannulation, compression pauses, and ECG during the pause were verified by physician review of patient records and physiological signals. Pauses were excluded if return of spontaneous circulation occurred during the pause (pressure pulses associated with ECG complexes). Compression, mean, and decompression ABP for 10 compressions before/after each pause and the mean ABP during the pause were measured with custom MATLAB code. The relationship between pause duration and ABP recovery was investigated using linear regression.

RESULTS

We included 56 patients with a total of 271 pauses (pause duration: median = 11 sec, Q1 = 7 sec, Q3 = 18 sec). Mean ABP dropped from 53 ± 10 mmHg for the last pre-pause compression to 33 ± 7 mmHg during the pause. Compression and mean ABP recovered to >90% of pre-pause pressure within 2 compressions, or 1.7 sec. Pause duration did not affect the recovery of ABP post-pause (R2: 0.05, 0.03, 0.01 for compression, mean, and decompression ABP, respectively).

CONCLUSIONS

ABP generated by mechanical CPR recovered quickly after pauses. Recovery of ABP after a pause was independent of pause duration.

Mechanical active compression-decompression versus standard mechanical cardiopulmonary resuscitation: A randomised haemodynamic out-of-hospital cardiac arrest study

BACKGROUND

Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) utilises a suction cup to lift the chest-wall actively during the decompression phase (AD). We hypothesised that mechanical ACD-CPR (Intervention), with AD up to 30 mm above the sternal resting position, would generate better haemodynamic results than standard mechanical CPR (Control).

METHODS

This out-of-hospital adult non-traumatic cardiac arrest trial was prospective, block-randomised and non-blinded. We included intubated patients with capnography recorded during mechanical CPR. Exclusion criteria were pregnancy, prisoners, and prior chest surgery. The primary endpoint was maximum tidal carbon dioxide partial pressure (p_MTCO₂) and secondary endpoints were oxygen saturation of cerebral tissue (SctO₂), invasive arterial blood pressures and CPR-related injuries. Intervention device lifting force performance was categorised as Complete AD (≥30 Newtons) or Incomplete AD (≤10 Newtons). Haemodynamic data, analysed as one measurement for each parameter per ventilation (Observation Unit, OU) with non-linear regression statistics are reported as mean (standard deviation). A two-sided p-value < 0.05 was considered as statistically significant.

RESULTS

Of 221 enrolled patients, 210 were deemed eligible (Control 109, Intervention 101). The Control vs. Intervention results showed no significant differences for p_MTCO₂: 29(17) vs 29(18) mmHg (p = 0.86), blood pressures during compressions: 111(45) vs. 101(68) mmHg (p = 0.93) and decompressions: 21(20) vs. 18(18) mmHg (p = 0.93) or for SctO₂%: 55(36) vs. 57(9) (p = 0.42). The 48 patients who received Complete AD in > 50% of their OUs had higher SctO₂ than Control patients: 58(11) vs. 55(36)% (p < 0.001).

CONCLUSIONS

Mechanical ACD-CPR provided similar haemodynamic results to standard mechanical CPR. The Intervention device did not consistently provide Complete AD.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier (NCT number): NCT02479152. The Haemodynamic Effects of Mechanical Standard and Active Chest Compression-decompression During Out-of-hospital CPR.

[CME: Mechanical Assist Devices in Cardiopulmonary Resuscitation]

CME: Mechanical Assist Devices in Cardiopulmonary Resuscitation Abstract. Early high-quality cardiopulmonary resuscitation in the event of a cardiac arrest is the most effective measure to improve the outcome. With the aim of improving the quality of resuscitation and replacing the need of manual compression, various mechanical assist devices have been developed and are used in the clinical practice. When should they be used, whether do they lead to better outcomes and what injuries are they associated with? These questions have been examined in several studies and the following review will provide an overview.

Comparison of hemodynamic effects and resuscitation outcomes between automatic simultaneous sterno-thoracic cardiopulmonary resuscitation device and LUCAS in a swine model of cardiac arrest

Introduction

Mechanical cardiopulmonary resuscitation (CPR) devices are widely used to rescue patients from cardiac arrest. This study aimed to compare hemodynamic effects and resuscitation outcomes between a motor-driven, automatic simultaneous sterno-thoracic cardiopulmonary resuscitation device and the Lund University cardiac arrest system (LUCAS).

Material and methods

After 2 minutes of electrically induced ventricular fibrillation (VF), Yorkshire pigs (weight 35–60 kg) received CPR with an automatic simultaneous sterno-thoracic CPR device (X-CPR group, n = 13) or the Lund University cardiac arrest system (LUCAS group, n = 12). Basic life support for 6 minutes and advanced cardiovascular life support for 12 minutes, including defibrillation and epinephrine administration, were provided. Hemodynamic parameters and resuscitation outcomes, including return of spontaneous circulation (ROSC), 24-hour survival, and cerebral performance category (CPC) at 24 hours, were evaluated.

Results

Hemodynamic parameters, including aortic pressures, coronary perfusion pressure, carotid blood flow, and end-tidal carbon dioxide pressure were not significantly different between the two groups. Resuscitation outcomes were also not significantly different between the groups (X-CPR vs. LUCAS; rate of ROSC: 31% vs 25%, p = 1.000; 24-hour survival rate: 31% vs 17%, p = 0.645; neurological outcome with CPC ≤2: 31% vs 17%, p = 0.645). Also no significant difference in incidence complications associated with resuscitation was found between the groups.

Conclusions

CPR with a motor-driven X-CPR and CPR with the LUCAS produced similar hemodynamic effects and resuscitation outcomes in a swine model of cardiac arrest.

Mechanical chest compressions for cardiac arrest in the cath-lab: when is it enough and who should go to extracorporeal cardio pulmonary resuscitation?

BACKGROUND

Treating patients in cardiac arrest (CA) with mechanical chest compressions (MCC) during percutaneous coronary intervention (PCI) is now routine in many coronary catheterization laboratories (cath-lab) and more aggressive treatment modalities, including extracorporeal CPR are becoming more common. The cath-lab setting enables monitoring of vital physiological parameters and other clinical factors that can potentially guide the resuscitation effort. This retrospective analysis attempts to identify such factors associated with ROSC and survival.

METHODS

In thirty-five patients of which background data, drugs used during the resuscitation and the intervention, PCI result, post ROSC-treatment and physiologic data collected during CPR were compared for prediction of ROSC and survival.

RESULTS

Eighteen (51%) patients obtained ROSC and 9 (26%) patients survived with good neurological outcome. There was no difference between groups in regards of background data. Patients arriving in the cath-lab with ongoing resuscitation efforts had lower ROSC rate (22% vs 53%; p = 0.086) and no survivors (0% vs 50%, p = 0.001). CPR time also differentiated resuscitation outcomes (ROSC: 18 min vs No ROSC: 50 min; p = 0.007 and Survivors: 10 min vs No Survivors: 45 min; p = 0.001). Higher arterial diastolic blood pressure was associated with ROSC: 30 mmHg vs No ROSC: 19 mmHg; p = 0.012).

CONCLUSION

Aortic diastolic pressure during CPR is the most predictive physiological parameter of resuscitation success. Ongoing CPR upon arrival at the cath-lab and continued MCC beyond 10-20 min in the cath-lab were both predictive of poor outcomes. These factors can potentially guide decisions regarding escalation and termination of resuscitation efforts.

Comparative Analysis of Emergency Medical Service Provider Workload During Simulated Out-of-Hospital Cardiac Arrest Resuscitation Using Standard Versus Experimental Protocols and Equipment

INTRODUCTION

Protocolized automation of critical, labor-intensive tasks for out-of-hospital cardiac arrest (OHCA) resuscitation may decrease Emergency Medical Services (EMS) provider workload. A simulation-based assessment method incorporating objective and self-reported metrics was developed and used to quantify workloads associated with standard and experimental approaches to OHCA resuscitation.

METHODS

Emergency Medical Services-Basic (EMT-B) and advanced life support (ALS) providers were randomized into two-provider mixed-level teams and fitted with heart rate (HR) monitors for continuous HR and energy expenditure (EE) monitoring. Subjects' resting salivary α-amylase (sAA) levels were measured along with Borg perceived exertion scores and multidimensional workload assessments (NASA-TLX). Each team engaged in the following three OHCA simulations: (1) baseline simulation in standard BLS/ALS roles; (2) repeat simulation in standard roles; and then (3) repeat simulation in reversed roles, ie, EMT-B provider performing ALS tasks. Control teams operated with standard state protocols and equipment; experimental teams used resuscitation-automating devices and accompanying goal-directed algorithmic protocol for simulations 2 and 3. Investigators video-recorded resuscitations and analyzed subjects' percent attained of maximal age-predicted HR (%mHR), EE, sAA, Borg, and NASA-TLX measurements.

RESULTS

Ten control and ten experimental teams completed the study (20 EMT-Basic; 1 EMT-Intermediate, 8 EMT-Cardiac, 11 EMT-Paramedic). Median %mHR, EE, sAA, Borg, and NASA-TLX scores did not differ between groups at rest. Overall multivariate analyses of variance did not detect significant differences; univariate analyses of variance for changes in %mHR, Borg, and NASA-TLX from resting state detected significant differences across simulations (workload reductions in experimental groups for simulations 2 and 3).

CONCLUSIONS

A simulation-based OHCA resuscitation performance and workload assessment method compared protocolized automation-assisted resuscitation with standard response. During exploratory application of the assessment method, subjects using the experimental approach appeared to experience reduced levels of physical exertion and perceived workload than control subjects.

Evolving Strategies in Cardiac Arrest Management

Cardiac arrest is a leading cause of death in the United States, with a hospital discharge rate of approximately 10%. International resuscitation guidelines offer standardized cardiac arrest management approaches, but beyond the guidelines, are promising innovations to improve resuscitative care. Although clinical data do not yet support the routine use of mechanical chest compressions, corticosteroids, thrombolytics, and adjunctive ventilation devices during arrest, these therapies may have an important role in select patients. Extracorporeal membrane oxygenation during cardiopulmonary resuscitation is a promising advancement and may have survival benefit in select patients. The evidence for standard therapies and these innovations is discussed.

Prompt use of mechanical cardiopulmonary resuscitation in out-of-hospital cardiac arrest: the MECCA study report

INTRODUCTION

Early use of mechanical cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) may improve survival outcomes. Current evidence for such devices uses outcomes from an intention-to-treat (ITT) perspective. We aimed to determine whether early use of mechanical CPR using a LUCAS 2 device results in better outcomes.

METHODS

A prospective, randomised, multicentre study was conducted over one year with LUCAS 2 devices in 14 ambulances and manual CPR in 32 ambulances to manage OHCA. The primary outcome was return of spontaneous circulation (ROSC). Secondary outcomes were survival at 24 hours, discharge from hospital and 30 days.

RESULTS

Of the 1,274 patients recruited, 1,191 were eligible for analysis. 889 had manual CPR and 302 had LUCAS CPR. From an ITT perspective, outcomes for manual and LUCAS CPR were: ROSC 29.2% and 31.1% (odds ratio [OR] 1.09, 95% confidence interval [CI] 0.82-1.45; p = 0.537); 24-hour survival 11.2% and 13.2% (OR 1.20, 95% CI 0.81-1.78; p = 0.352); survival to discharge 3.6% and 4.3% (OR 1.20, 95% CI 0.62-2.33; p = 0.579); and 30-day survival 3.0% and 4.0% (OR 1.32, 95% CI 0.66-2.64; p = 0.430), respectively. By as-treated analysis, outcomes for manual, early LUCAS and late LUCAS CPR were: ROSC 28.0%, 36.9% and 24.5%; 24-hour survival 10.6%, 15.5% and 8.2%; survival to discharge 2.9%, 5.8% and 2.0%; and 30-day survival 2.4%, 5.8% and 0.0%, respectively. Adjusted OR for survival with early LUCAS vs. manual CPR was 1.47 after adjustment for other variables (p = 0.026).

CONCLUSION

This study showed a survival benefit with LUCAS CPR as compared to manual CPR only, when the device was applied early on-site.

Standardized model of porcine resuscitation using a custom-made resuscitation board results in optimal hemodynamic management

AIM

Standardized modeling of cardiac arrest and cardiopulmonary resuscitation (CPR) is crucial to evaluate new treatment options. Experimental porcine models are ideal, closely mimicking human-like physiology. However, anteroposterior chest diameter differs significantly, being larger in pigs and thus poses a challenge to achieve adequate perfusion pressures and consequently hemodynamics during CPR, which are commonly achieved during human resuscitation. The aim was to prove that standardized resuscitation is feasible and renders adequate hemodynamics and perfusion in pigs, using a specifically designed resuscitation board for a pneumatic chest compression device.

METHODS AND RESULTS

A "porcine-fit" resuscitation board was designed for our experiments to optimally use a pneumatic compression device (LUCAS® II, Physio-Control Inc.), which is widely employed in emergency medicine and ideal in an experimental setting due to its high standardization. Asphyxial cardiac arrest was induced in 10 German hybrid landrace pigs and cardiopulmonary resuscitation was performed according to ERC/AHA 2015 guidelines with mechanical chest compressions. Hemodynamics were measured in the carotid and pulmonary artery. Furthermore, arterial blood gas was drawn to assess oxygenation and tissue perfusion. The custom-designed resuscitation board in combination with the LUCAS® device demonstrated highly sufficient performance regarding hemodynamics during CPR (mean arterial blood pressure, MAP 46 ± 1 mmHg and mean pulmonary artery pressure, mPAP of 36 ± 1 mmHg over the course of CPR). MAP returned to baseline values at 2 h after ROSC (80 ± 4 mmHg), requiring moderate doses of vasopressors. Furthermore, stroke volume and contractility were analyzed using pulse contour analysis (106 ± 3 ml and 1097 ± 22 mmHg/s during CPR). Blood gas analysis revealed CPR-typical changes, normalizing in the due course. Thermodilution parameters did not show persistent intravascular volume shift.

CONCLUSION

Standardized cardiopulmonary resuscitation is feasible in a porcine model, achieving adequate hemodynamics and consecutive tissue perfusion of consistent quality.

Comparable Outcome of Out-of-Hospital Cardiac Arrest and In-Hospital Cardiac Arrest Treated With Extracorporeal Life Support

Extracorporeal life support (ECLS) has shown benefits in the management of refractory in-hospital cardiac arrest (IHCA) by improving survival. Nonetheless, the results concerning out-of-hospital refractory cardiac arrests (OHCA) remain uncertain. The aim of our investigation was to compare survival between the two groups. We realized a single-center retrospective, observational study of all patients who presented IHCA or OHCA treated with ECLS between 2011 and 2015. Multivariate analysis was realized to determine independent factors associated with mortality. Over the 4-year period, 65 patients were included, 43 in the IHCA group (66.2%), and 22 (33.8%) in the OHCA group. The duration of low flow was significantly longer in the OHCA group (60 vs. 90 min, P = 0.004). Survival to discharge from the hospital was identical in the two groups (27% in the OHCA group vs. 23% in the IHCA group, P = 0.77). All surviving patients in the OHCA group had a cerebral performance categories score of 1-2. In multivariate analysis, we found that the initial lactate level and baseline blood creatinine were independently associated with mortality. We found comparable survival and neurological score in patients who presented IHCA and OHCA treated with ECLS. We believe that appropriate selection of patients and optimization of organ perfusion during resuscitation can lead to good results in patients with OHCA treated with ECLS.

Simulation-based Randomized Comparative Assessment of Out-of-Hospital Cardiac Arrest Resuscitation Bundle Completion by Emergency Medical Service Teams Using Standard Life Support or an Experimental Automation-assisted Approach

INTRODUCTION

Effective resuscitation of out-of-hospital cardiac arrest (OHCA) patients is challenging. Alternative resuscitative approaches using electromechanical adjuncts may improve provider performance. Investigators applied simulation to study the effect of an experimental automation-assisted, goal-directed OHCA management protocol on EMS providers' resuscitation performance relative to standard protocols and equipment.

METHODS

Two-provider (emergency medical technicians (EMT)-B and EMT-I/C/P) teams were randomized to control or experimental group. Each team engaged in 3 simulations: baseline simulation (standard roles); repeat simulation (standard roles); and abbreviated repeat simulation (reversed roles, i.e., basic life support provider performing ALS tasks). Control teams used standard OHCA protocols and equipment (with high-performance cardiopulmonary resuscitation training intervention); for second and third simulations, experimental teams performed chest compression, defibrillation, airway, pulmonary ventilation, vascular access, medication, and transport tasks with goal-directed protocol and resuscitation-automating devices. Videorecorders and simulator logs collected resuscitation data.

RESULTS

Ten control and 10 experimental teams comprised 20 EMT-B's; 1 EMT-I, 8 EMT-C's, and 11 EMT-P's; study groups were not fully matched. Both groups suboptimally performed chest compressions and ventilations at baseline. For their second simulations, control teams performed similarly except for reduced on-scene time, and experimental teams improved their chest compressions (P=0.03), pulmonary ventilations (P<0.01), and medication administration (P=0.02); changes in their performance of chest compression, defibrillation, airway, and transport tasks did not attain significance against control teams' changes. Experimental teams maintained performance improvements during reversed-role simulations.

CONCLUSION

Simulation-based investigation into OHCA resuscitation revealed considerable variability and improvable deficiencies in small EMS teams. Goal-directed, automation-assisted OHCA management augmented select resuscitation bundle element performance without comprehensive improvement.

Minnesota Resuscitation Consortium's Advanced Perfusion and Reperfusion Cardiac Life Support Strategy for Out-of-Hospital Refractory Ventricular Fibrillation

Background

In 2015, the Minnesota Resuscitation Consortium (MRC) implemented an advanced perfusion and reperfusion life support strategy designed to improve outcome for patients with out‐of‐hospital refractory ventricular fibrillation/ventricular tachycardia (VF/VT). We report the outcomes of the initial 3‐month period of operations.

Methods and Results

Three emergency medical services systems serving the Minneapolis–St. Paul metro area participated in the protocol. Inclusion criteria included age 18 to 75 years, body habitus accommodating automated Lund University Cardiac Arrest System (LUCAS) cardiopulmonary resuscitation (CPR), and estimated transfer time from the scene to the cardiac catheterization laboratory of ≤30 minutes. Exclusion criteria included known terminal illness, Do Not Resuscitate/Do Not Intubate status, traumatic arrest, and significant bleeding. Refractory VF/VT arrest was defined as failure to achieve sustained return of spontaneous circulation after treatment with 3 direct current shocks and administration of 300 mg of intravenous/intraosseous amiodarone. Patients were transported to the University of Minnesota, where emergent advanced perfusion strategies (extracorporeal membrane oxygenation; ECMO), followed by coronary angiography and primary coronary intervention (PCI), were performed, when appropriate. Over the first 3 months of the protocol, 27 patients were transported with ongoing mechanical CPR. Of these, 18 patients met the inclusion and exclusion criteria. ECMO was placed in 83%. Seventy‐eight percent of patients had significant coronary artery disease with a high degree of complexity and 67% received PCI. Seventy‐eight percent of patients survived to hospital admission and 55% (10 of 18) survived to hospital discharge, with 50% (9 of 18) achieving good neurological function (cerebral performance categories 1 and 2). No significant ECMO‐related complications were encountered.

Conclusions

The MRC refractory VF/VT protocol is feasible and led to a high functionally favorable survival rate with few complications.

The Price of a Helping Hand: Modeling the Outcomes and Costs of Bystander CPR

OBJECTIVE

Early, high-quality, minimally interrupted bystander cardio-pulmonary resuscitation (BCPR) is essential for out-of-hospital cardiac arrest survival. However, rates of bystander intervention remain low in many geographic areas. Community CPR programs have been initiated to combat these low numbers by teaching compression-only CPR to laypersons. This study examined bystander CPR and the cost-effectiveness of a countywide CPR program to improve out-of-hospital cardiac arrest survival.

METHODS

A 2-year retrospective review of emergency medical services (EMS) run reports for adult nontraumatic cardiac arrests was performed using existing prehospital EMS quality assurance data. The incidence and success of bystander CPR to produce prehospital return of spontaneous circulation and favorable neurologic outcomes at hospital discharge were analyzed. The outcomes were paired with cost data for the jurisdiction's community CPR program to develop a cost-effectiveness model.

RESULTS

During the 23-month study period, a total of 371 nontraumatic adult out-of-hospital cardiac arrests occurred, with a 33.4% incidence of bystander CPR. Incremental cost-effectiveness analysis for the community CPR program demonstrated a total cost of $22,539 per quality-adjusted life-year (QALY). A significantly increased proportion of those who received BCPR also had an automated external defibrillator (AED) applied. There was no correlation between witnessed arrest and performance of BCPR. A significantly increased proportion of those who received BCPR were found to be in a shockable rhythm when the initial ECG was performed. In the home setting, the chances of receiving BCPR were significantly smaller, whereas in the public setting a nearly equal number of people received and did not receive BCPR. Witnessed arrest, AED application, public location, and shockable rhythm on initial ECG were all significantly associated with positive ROSC and neurologic outcomes. A home arrest was significantly associated with worse neurologic outcome.

CONCLUSIONS

Cost-effectiveness analysis demonstrates that a community CPR outreach program is a cost-effective means for saving lives when compared to other healthcare-related interventions. Bystander CPR showed a clear trend toward improving the neurologic outcome of survivors. The findings of this study indicate a need for additional research into the economic effects of bystander CPR.

Automatic chest compression devices--when do they make sense?

The current resuscitation guidelines of the European Resuscitation Council do not include automatic chest compression devices (ACDs) as standard equipment to support cardiopulmonary resuscitation attempts. One possible reason could be the lack of a list of indications and contraindications for the use of ACD systems. This review should give a summary of current studies and developments according to ACD systems and deliver a list of possible applications. Furthermore, we discuss some ethical problems with cardiopulmonary resuscitation attempts and, in particular, with ACD systems. The use of ACDs occurs instead of manual chest compression. Because of this, there is no reason for changing the current guidelines, especially termination recommendations while using ACD systems. From our point of view, ACDs are a very good supplement to the current standard of resuscitation according to the European Resuscitation Council guidelines.

Cardiac aetiology of cardiac arrest: percutaneous coronary interventions during and after cardiopulmonary resuscitation

Management and prevention of cardiac arrest in the setting of heart disease is a challenge for modern cardiology. After reviewing the aetiology of sudden cardiac death and discussing the way to identify candidates at risk, we emphasise the role of percutaneous coronary interventions during and after cardiopulmonary resuscitation in the treatment of patients with return of spontaneous circulation after cardiac arrest.

Percutaneous Assist Device for Cardiopulmonary Resuscitation

Persistent cardiac arrest is often caused by coronary ischemia. Urgent revascularization during on-going resuscitation with the support of percutaneous left ventricular assist devices (PVAD) may be feasible and can have the potential to improve the prognosis. Transport during resuscitation is a challenge that may be overcome with the use of cardiopulmonary resuscitation devices. In the catheterization laboratory, rapid deployment of PVAD may reduce ischemia, contribute to electrical stabilization of the heart, and facilitate definite treatment with percutaneous coronary intervention. After revascularization, PVAD therapy may promote myocardial recovery and improve vital organ perfusion in a critical phase.

The effects of a newly developed miniaturized mechanical chest compressor on outcomes of cardiopulmonary resuscitation in a porcine model*

OBJECTIVE

When the duration of cardiac arrest is prolonged, reperfusion of the vital organs by effective chest compression is the most important intervention for successful resuscitation. We investigated the effects of a newly developed miniaturized chest compressor on the outcomes of cardiopulmonary resuscitation.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

University-affiliated animal research laboratory.

SUBJECTS

Thirty male domestic pigs.

INTERVENTIONS

Ventricular fibrillation was induced in 30 male domestic pigs weighing 35 ± 2 kg. Cardiopulmonary resuscitation was initiated after 7 mins of untreated ventricular fibrillation. The animals were randomized to receive mechanical chest compression with a miniaturized chest compressor, a LUCAS device or a Thumper device. After 5 mins of cardiopulmonary resuscitation, a 150-J defibrillation was delivered. If resuscitation was not successful, cardiopulmonary resuscitation was continued for 2 mins before the next defibrillation. The protocol was continued until successful resuscitation or for a total of 15 mins of cardiopulmonary resuscitation. The animals were observed for 72 hrs after resuscitation.

MEASUREMENTS AND MAIN RESULTS

The miniaturized chest compressor generated significantly greater coronary perfusion pressure, end-tidal PCO2, carotid blood flow, and intrathoracic negative pressure, with significantly lower compression depth and fewer rib fractures when compared with both the LUCAS and Thumper devices. Both the miniaturized chest compressor and LUCAS devices required lower numbers of defibrillation for successful resuscitation when compared with the Thumper device. This was associated with lower prevalence of recurrent ventricular fibrillation and better postresuscitation myocardial and neurological function when compared with the Thumper device.

CONCLUSIONS

The miniaturized chest compressor improves hemodynamic efficacy and the success of cardiopulmonary resuscitation with significantly less injury, which is as effective as the LUCAS device. It may provide a new option for cardiopulmonary resuscitation.

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

Background

Mechanical chest compressions (CCs) have been shown capable of maintaining circulation in humans suffering cardiac arrest for extensive periods of time. Reports have documented a visually normalized coronary blood flow during angiography in such cases (TIMI III flow), but it has never been actually measured. Only indirect measurements of the coronary circulation during cardiac arrest with on-going mechanical CCs have been performed previously through measurement of the coronary perfusion pressure (CPP). In this study our aim was to correlate average peak coronary flow velocity (APV) to CPP during mechanical CCs.

Methods

In a closed chest porcine model, cardiac arrest was established through electrically induced ventricular fibrillation (VF) in eleven pigs. After one minute, mechanical chest compressions were initiated and then maintained for 10 minutes upon which the pigs were defibrillated. Measurements of coronary blood flow in the left anterior descending artery were made at baseline and during VF with a catheter based Doppler flow fire measuring APV. Furthermore measurements of central (thoracic) venous and arterial pressures were also made in order to calculate the theoretical CPP.

Results

Average peak coronary flow velocity was significantly higher compared to baseline during mechanical chests compressions and this was observed during the entire period of mechanical chest compressions (12 - 39% above baseline). The APV slowly declined during the 10 min period of mechanical chest compressions, but was still higher than baseline at the end of mechanical chest compressions. CPP was simultaneously maintained at > 20 mmHg during the 10 minute episode of cardiac arrest.

Conclusion

Our study showed good correlation between CPP and APV which was highly significant, during cardiac arrest with on-going mechanical CCs in a closed chest porcine model. In addition APV was even higher during mechanical CCs compared to baseline. Mechanical CCs can, at minimum, re-establish coronary blood flow in non-diseased coronary arteries during cardiac arrest.