Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation

Echocardiographic clues of the "atrial pump mechanism" during cardiopulmonary resuscitation

Instead of the ventricles, atria may be the cardiac structures mainly compressed during cardiopulmonary resuscitation (CPR). This study aimed to assess the prevalence and the mechanical characteristics of atrial compression, named the "atrial pump mechanism", in patients undergoing CPR. A retrospective cohort study was conducted on patients with witnessed refractory out-of-hospital cardiac arrest who were admitted to a tertiary referral center for extracorporeal CPR. The area of maximal compression (AMC) by chest compressions was assessed by transesophageal echocardiography. Right atrial wall excursion (RAWE), left atrial fractional shortening (LAFS), right ventricular fractional area change (RVFAC), and left ventricular fractional shortening (LVFS) were measured. Common carotid and middle cerebral artery peak velocities were assessed using color-Doppler imaging as markers of cardiac outflow and cerebral perfusion. Forty patients were included in the study. Five (12.5%) had AMC over the atria. The atrial pump pattern was characterized by marked atrial compression with higher RAWE and LAFS values compared to the other patients (p < 0.001). Common carotid Doppler and transcranial Doppler-velocity patterns were detectable in all patients with open left ventricular outflow tract, without differences between patients. CPR was successful in four patients (80%) with atrial pump compared to 14 (40%) with no atrial pump mechanism (p = 0.155). In this series of selected patients with witnessed cardiac arrest, the prevalence of the atrial pump mechanism was not negligible. It may contribute to forward blood flow and the maintenance of cerebral perfusion during prolonged cardiopulmonary resuscitation.

Successful transplantation of LUCAS device assisted uncontrolled DCD kidneys with prolonged relative warm ischemia time: An underutilized option in North America

Approximately 25% of deceased donors in the United States are procured in a donation after circulatory death (DCD) setting. Successful transplant outcomes from uncontrolled DCD (uDCD) practices have been reported in multiple European programs. They utilize established protocols for uDCD procurement with normo-thermic or hypothermic regional perfusion to reduce ischemic damage. Further, manual or mechanical chest compressions using extrinsic devices, such as the LUCAS device, are implemented to maintain circulation before organ retrieval. Currently, uDCDs are not a major part of DCD organ utilization in the United States. We report our experience with utilization of kidneys from uDCD with the use of the LUCAS device without normothermic or hypothermic regional perfusion. We transplanted four kidneys from three uDCD donors without utilization of in situ regional perfusion and with prolonged relative warm ischemia time (rWIT) (>100 min). All recipients had functional renal allografts and improved renal function after the transplant. To our knowledge, this is the 1st successful series reported in the United States of the utilization of kidneys from uDCDs without the utilization of in situ perfusion to maintain organ preservation with prolonged rWIT.

Perceptions of nurses regarding quality of adult cardiopulmonary resuscitation in Ghana: a qualitative study

OBJECTIVES

Cardiopulmonary resuscitation (CPR) is a necessary life-saving emergency intervention for patients with cardiac arrest and other medical conditions. The study's primary objective was to qualitatively explore nurses' perceptions of the quality of adult cardiopulmonary resuscitation in Ghana.

METHODS

An exploratory descriptive qualitative study was conducted among 13 purposively sampled nurses in Ghana. We collected thirteen face-to-face and telephone interviews using a semi-structured interview guide. Data were transcribed verbatim and analysed using the thematic analysis approach recommended by Braun and Clarke.

RESULTS

Data analysis revealed that nurses were filled with positive emotions when patients regained consciousness following resuscitation. When the otherwise happens, they tend to become tortured psychologically and filled with negative emotions. Besides, environmental factors such as the time of initiating CPR following a cardiac arrest, the availability and appropriateness of equipment and medications, workplace ergonomics, and institutional regulations affected the quality of resuscitation practices of nurses. Participants perceived that attitudes of condemnation, prejudice, apathy and skills deficiency also impacted the quality of resuscitation practices. Significant aspects of self-reported behavioural competence that affected resuscitation were knowledge and skills of CPR, confidence in initiating CPR, and the need for effort maximisation.

CONCLUSION

This study revealed several non-medical factors that influenced the resuscitation practices of nurses from their perspective. Nurses need to maximise their effort toward seeking further education in speciality areas such as emergency nursing and critical care nursing to guide their CPR practices and other newly emerging evidence-based protocols.

Mechanical chest compression and extracorporeal life support for out-of-hospital cardiac arrest. A 30-month observational study in the metropolitan area of Milan, Italy

BACKGROUND

Return of spontaneous circulation (ROSC) is achieved in 25% of out-of-hospital cardiac arrest (OHCA) patients. Mechanical chest compression (mechCPR) may maintain better perfusion during transport, allowing hospital treatments like extracorporeal circulation life support (ECLS). We aim to assess the effectiveness of a pre-hospital protocol introduction.

METHODS

Observational, retrospective study assessing all OHCA patients aged 12-75, with no-flow time <20 min in a metropolitan area (Milan, Italy, 2013-2016).

PRIMARY OUTCOMES

ROSC and Cerebral Performance Category score (CPC) ≤2 at hospital discharge. Logistic regressions with multiple comparison adjustments balanced with propensity scores calculated with inverse probability of treatment weighting were performed.

RESULTS

1366 OHCA were analysed; 305 received mechCPR, 1061 manual chest compressions (manCPR), and 108 ECLS. ROSC and CPC ≤2 were associated with low-flow minutes (odds ratio [95% confidence interval] 0.90 [0.88-0.91] and 0.90 [0.87-0.93]), shockable rhythm (2.52 [1.71-3.72] and 10.68 [5.63-20.28]), defibrillations number (1.15 [1.07-1.23] and 1.15 [1.04-1.26]), and mechCPR (1.86 [1.17-2.96] and 2.06 [1.11-3.81]). With resuscitation times >13 min, mechCPR achieved more frequently ROSC compared to manCPR. Among ECLS patients, 70% had time exceeding protocol: 8 (7.5%) had CPC ≤2 (half of them with low-flow times between 45 and 90 min), 2 (1.9%) survived with severe neurological disabilities, and 13 brain-dead (12.0%) became organ donors.

CONCLUSIONS

MechCPR patients achieved ROSC more frequently than manual CPR patients; mechCPR was a crucial factor in an ECLS protocol for refractory OHCA. ECLS offered a chance of survival to patients who would otherwise die.

Suction cup on a piston-based chest compression device improves coronary perfusion pressure and cerebral oxygenation during experimental cardiopulmonary resuscitation

Introduction

The presented study aimed to investigate whether a mechanical chest compression piston device with a suction cup assisting chest recoil could impact the hemodynamic status when compared to a bare piston during cardiopulmonary resuscitation.

Methods

16 piglets were anesthetized and randomized into 2 groups. After 3 minutes of induced ventricular fibrillation, a LUCAS 3 device was used to perform chest compressions, in one group a suction cup was mounted on the device’s piston, while in the other group, compressions were performed by the bare piston. The device was used in 30:2 mode and the animals were manually ventilated. Endpoints of the study were: end tidal carbon dioxide, coronary and cerebral perfusion pressures, and brain oxygenation (measured using near infrared spectroscopy). At the end of the protocol, the animals that got a return to spontaneous circulation were observed for 60 minutes, then euthanized.

Results

No difference was found in end tidal carbon dioxide or tidal volumes. Coronary perfusion pressure and cerebral oxygenation were higher in the Suction cup group over the entire experiment time, while cerebral perfusion pressure was higher only in the last 5 minutes of CPR. A passive tidal volume (air going in and out the airways during compressions) was detected and found correlated to end tidal carbon dioxide.

Conclusions

The use of a suction cup on a piston-based chest compression device did not increase end tidal carbon dioxide, but it was associated to a higher coronary perfusion pressure.

Traumatic Injuries Following Mechanical versus Manual Chest Compression

Objective

Survival after out-of-hospital cardiac arrest (OHCA) depends on multiple factors, mostly quality of chest compressions. Studies comparing manual compression with a mechanical active compression-depression device (ACD) have yielded controversial results in terms of outcomes and injury. The aim of the present study was to determine whether out-of-hospital ACD cardiopulmonary resuscitation (CPR) use is associated with more skeletal fractures and/or internal injuries than manual compression, with similar duration of cardiopulmonary resuscitation (CPR) between the groups.

Methods

The cohort included all patients diagnosed with out-of-hospital cardiac arrest (OHCA) at a tertiary medical center between January 2018 and June 2019 who achieved return of spontaneous circulation (ROSC). The primary outcome measure was the incidence of skeletal fractures and/or internal injuries in the two groups. Secondary outcome measures were clinical factors contributing to skeletal fracture/internal injuries and to achievement of ROSC during CPR.

Results

Of 107 patients enrolled, 45 (42%) were resuscitated with manual chest compression and 62 (58%) with a piston-based ACD device (LUCAS). The duration of chest compression was 46.0 minutes vs. 48.5 minutes, respectively (p=0.82). There were no differences in rates of ROSC (53.2% vs.50.8%, p=0.84), cardiac etiology of OHCA (48.9% vs.43.5%, p=0.3), major complications (ribs/sternum fracture, pneumothorax, hemothorax, lung parenchymal damage, major bleeding), or any complication (20.5% vs.12.1%, p=0.28). On multivariate logistic regression analysis, factors with the highest predictive value for ROSC were cardiac etiology (OR 1.94;CI 2.00-12.94) and female sex (OR 1.94;CI 2.00-12.94). Type of arrhythmia had no significant effect. Use of the LUCAS was not associated with ROSC (OR 0.73;CI 0.34-2.1).

Conclusion

This is the first study to compare mechanical and manual out-of-hospital chest compression of similar duration to ROSC. The LUCAS did not show added benefit in terms of ROSC rate, and its use did not lead to a higher risk of traumatic injury. ACD devices may be more useful in cases of delayed ambulance response times, or events in remote locations.

Manual and Mechanical Induced Peri-Resuscitation Injuries-Post-Mortem and Clinical Findings

(1) Background: Injuries related to resuscitation are not usually systematically recorded and documented. By evaluating this data, conclusions could be drawn about the quality of the resuscitation, with the aim of improving patient care and safety. (2) Methods: We are planning to conduct a multicentric, retrospective 3-phased study consisting of (1) a worldwide literature review (scoping review), (2) an analysis of anatomical pathological findings from local institutions in North Rhine-Westphalia, Germany to assess the transferability of the review data to the German healthcare system, and (3) depending on the results, possibly establishing potential prospective indicators for resuscitation-related injuries as part of quality assurance measures. (3) Conclusions: From the comparison of literature and local data, the picture of resuscitation-related injuries will be focused on and quality indicators will be derived.

Pectus excavatum and mechanical chest compression of a dangerous bond

Pectus excavatum (PE) is a malformation of the chest characterized by a median depression of the sternum. The incidence of PE is between 0.1% and 0.8%. In the last decade mechanical chest compression devices (MCCD) became of particular interest in cardiopulmonary resuscitation. Different devices became available and this resulted in an increase in their use during CPR mainly for practical reasons. Despite their increasing use, little evidence existed for their effectiveness and little was known about complications. Skin lesions and fractures of sternum or ribs are the ones with the highest incidence. Whereas subdiaphragmatic lesions, in particular fatal liver injuries are uncommon and described only in few case reports. In a recent retrospective study, CT was used to determine the proper compression landmark and depth of cardiopulmonary resuscitation in PE patients. The authors showed that the mean Haller Index in PE patients was higher than in controls, thus exposing internal organs to a higher injury risk during standard CPR maneuvers. We report the first case, to our knowledge, of liver injury during mechanical CPR in a patient with PE. Awareness is being raised on tailoring mechanical CPR in patients with chest deformities. Further exploration is needed to determine if there is a strong correlation between mechanical CPR and organ damage in PE. We believe that this case highlights the importance of individualizing CPR techniques.

A new variant position of head-up CPR may be associated with improvement in the measurements of cranial near-infrared spectroscopy suggestive of an increase in cerebral blood flow in non-traumatic out-of-hospital cardiac arrest patients: A prospective interventional pilot study

AIM OF THE STUDY

This study aimed to investigate the effect of the head-up position implemented during cardiopulmonary resuscitation (CPR) on cerebral blood flow (CBF) using near-infrared spectroscopy in out-of-hospital cardiac arrest patients.

METHODS

Baseline characteristics (age, sex, cerebral performance category before cardiac arrest, witnessed cardiac arrest, bystander CPR, first monitored rhythm, no-flow time, prehospital low-flow time, CPR duration in the emergency department (ED), and reason for stopping CPR in the ED) were recorded. The changes of CBF were derived from the optical oscillation waveform measured by near-infrared spectroscopy in adult patients with out-of-hospital cardiac arrest by alternating head-up and supine positions at 4-minute intervals while performing CPR. The CBF velocity according to the head position was also evaluated using the time derivative of the oscillation waveform.

RESULTS

During the study period, 28 patients were enrolled. The median increase in CBF in the prefrontal area in the head-up position was 14.6% (Interquartile range, 8.8-65.0), more than that in the supine position. An increase in CBF was observed in the head-up position compared with the supine position in 83.3% of the patients included in the analysis.

CONCLUSION

CBF increased when the head-up position was used during CPR in non-traumatic out-of-hospital cardiac arrest patients. abberivation OHCA: out-of-hospital cardiac arrest, ROSC: return of spontaneous circulation, CBF: cerebral blood flow, CPR: cardiopulmonary resuscitation, EMT: emergency medical technician, ACD: active chest compression-decompression, ITD: impedance threshold device, HUP: head-up position, ICP: intracranial pressure, CePP: cerebral perfusion pressure, NIRS: Near-infrared spectroscopy, ED: emergency department, ALS: advanced life support, HbO2: oxy-haemoglobin, HbR: deoxy-haemoglobin, RMS: root-mean-square, IQR: interquartile rage, TCD: transcranial doppler, CVR: cerebrovascular resistance, MAP: mean arterial pressure.

Prognostic Impact of In-Hospital Use of Mechanical Cardiopulmonary Resuscitation Devices Compared with Manual Cardiopulmonary Resuscitation: A Nationwide Population-Based Observational Study in South Korea

Background and Objectives: This study analyzed the prognostic impact of mechanical cardiopulmonary resuscitation (CPR) devices in out-of-hospital cardiac arrest (OHCA) patients, in comparison to manual CPR. Materials and Methods: This study was a nationwide population-based observational study in South Korea. Data were retrospectively collected from 142,905 OHCA patients using the South Korean Out-of-Hospital Cardiac Arrest Surveillance database. We included adult OHCA patients who received manual or mechanical CPR in the emergency room. The primary outcome was survival at discharge and the secondary outcome was sustained return of spontaneous circulation (ROSC). Statistical analysis included propensity score matching and multivariate logistic regression. Results: A total of 19,045 manual CPR and 1125 mechanical CPR cases (671 AutoPulse^TM vs. 305 Thumper^TM vs. 149 LUCAS^TM) were included. In the matched multivariate analyses, all mechanical CPR devices were associated with a lower ROSC than that of manual CPR. AutoPulse^TM was associated with lower survival in the multivariate analysis after matching (aOR with 95% CI: 0.57 (0.33–0.96)), but the other mechanical CPR devices were associated with similar survival to discharge as that of manual CPR. Witnessed arrest was commonly associated with high ROSC, but the use of mechanical CPR devices and cardiac origin arrest were associated with low ROSC. Only target temperature management was the common predictor for high survival. Conclusions: The mechanical CPR devices largely led to similar survival to discharge as that of manual CPR in OHCA patients; however, the in-hospital use of the AutoPulse^TM device for mechanical CPR may significantly lower survival compared to manual CPR.

Extracellular Glutamate Concentration Increases Linearly in Proportion to Decreases in Residual Cerebral Blood Flow After the Loss of Membrane Potential in a Rat Model of Ischemia

BACKGROUND

Brain ischemia due to disruption of cerebral blood flow (CBF) results in increases in extracellular glutamate concentration and neuronal cell damage. However, the impact of CBF on glutamate dynamics after the loss of the membrane potential remains unknown.

MATERIALS AND METHODS

To determine this impact, we measured extracellular potential, CBF, and extracellular glutamate concentration in the parietal cortex in male Sprague-Dawley rats (n=21). CBF was reduced by bilateral occlusion of the common carotid arteries and exsanguination until loss of extracellular membrane potential was observed (low-flow group), or until CBF was further reduced by 5% to 10% of preischemia levels (severe-low-flow group). CBF was promptly restored 10 minutes after the loss of membrane potential. Histologic outcomes were evaluated 5 days later.

RESULTS

Extracellular glutamate concentration in the low-flow group was significantly lower than that in the severe-low-flow group. Moreover, increases in extracellular glutamate concentration exhibited a linear relationship with decreases in CBF after the loss of membrane potential in the severe-low-flow group, and the percentage of damaged neurons exhibited a dose-response relationship with the extracellular glutamate concentration. The extracellular glutamate concentration required to cause 50% neuronal damage was estimated to be 387 μmol/L, at 8.7% of preischemia CBF. Regression analyses revealed that extracellular glutamate concentration increased by 21 μmol/L with each 1% decrease in residual CBF and that the percentage of damaged neurons increased by 2.6%.

CONCLUSION

Our results indicate that residual CBF is an important factor that determines the extracellular glutamate concentration after the loss of membrane potential, and residual CBF would be one of the important determinants of neuronal cell prognosis.

Effects of rewarming with extracorporeal membrane oxygenation to restore oxygen transport and organ blood flow after hypothermic cardiac arrest in a porcine model

We recently documented that cardiopulmonary resuscitation (CPR) generates the same level of cardiac output (CO) and mean arterial pressure (MAP) during both normothermia (38 °C) and hypothermia (27 °C). Furthermore, continuous CPR at 27 °C provides O₂ delivery (ḊO₂) to support aerobic metabolism throughout a 3-h period. The aim of the present study was to investigate the effects of extracorporeal membrane oxygenation (ECMO) rewarming to restore ḊO₂ and organ blood flow after prolonged hypothermic cardiac arrest. Eight male pigs were anesthetized and immersion cooled to 27 °C. After induction of hypothermic cardiac arrest, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed with ECMO. Organ blood flow was measured using microspheres. After cooling with spontaneous circulation to 27 °C, MAP and CO were initially reduced to 66 and 44% of baseline, respectively. By 15 min after the onset of CPR, there was a further reduction in MAP and CO to 42 and 25% of baseline, respectively, which remained unchanged throughout the rest of 3-h CPR. During CPR, ḊO₂ and O₂ uptake (V̇O₂) fell to critical low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. Rewarming with ECMO restored MAP, CO, ḊO₂, and blood flow to the heart and to parts of the brain, whereas flow to kidneys, stomach, liver and spleen remained significantly reduced. CPR for 3-h at 27 °C with sustained lower levels of CO and MAP maintained aerobic metabolism sufficient to support ḊO₂. Rewarming with ECMO restores blood flow to the heart and brain, and creates a "shockable" cardiac rhythm. Thus, like continuous CPR, ECMO rewarming plays a crucial role in "the chain of survival" when resuscitating victims of hypothermic cardiac arrest.

Adrenaline improves regional cerebral blood flow, cerebral oxygenation and cerebral metabolism during CPR in a porcine cardiac arrest model using low-flow extracorporeal support

BACKGROUND

The effects of adrenaline on cerebral blood vessels during cardiopulmonary resuscitation (CPR) are not well understood. We developed an extracorporeal CPR model that maintains constant low systemic blood flow while allowing adrenaline-associated effects on cerebral vasculature to be assessed at different mean arterial pressure (MAP) levels independently of the effects on systemic blood flow.

METHODS

After eight minutes of cardiac arrest, low-flow extracorporeal life support (ECLS) (30 ml/kg/min) was started in fourteen pigs. After ten minutes, continuous adrenaline administration was started to achieve MAP values of 40 (n = 7) or 60 mmHg (n = 7). Measurements included intracranial pressure (ICP), cerebral perfusion pressure (CePP), laser-Doppler-derived regional cerebral blood flow (CBF), cerebral regional oxygen saturation (rSO₂), brain tissue oxygen tension (P_btO₂) and extracellular cerebral metabolites assessed by cerebral microdialysis.

RESULTS

During ECLS without adrenaline, regional CBF increased by only 5% (25th to 75th percentile: -3 to 14; p=0.2642) and P_btO₂ by 6% (0-15; p=0.0073) despite a significant increase in MAP to 28 mmHg (25-30; p<0.0001) and CePP to 10 mmHg (8-13; p<0.0001). Accordingly, cerebral microdialysis parameters showed a profound hypoxic-ischemic pattern. Adrenaline administration significantly improved regional CBF to 29±14% (p=0.0098) and 61±25% (p<0.001) and P_btO₂ to 15±11% and 130±82% (both p<0.001) of baseline in the MAP 40 mmHg and MAP 60 mmHg groups, respectively. Importantly, MAP of 60 mmHg was associated with metabolic improvement.

CONCLUSION

This study shows that adrenaline administration during constant low systemic blood flow increases CePP, regional CBF, cerebral oxygenation and cerebral metabolism.

Shock decision algorithm for use during load distributing band cardiopulmonary resuscitation

AIM

Chest compressions delivered by a load distributing band (LDB) induce artefacts in the electrocardiogram. These artefacts alter shock decisions in defibrillators. The aim of this study was to demonstrate the first reliable shock decision algorithm during LDB compressions.

METHODS

The study dataset comprised 5813 electrocardiogram segments from 896 cardiac arrest patients during LDB compressions. Electrocardiogram segments were annotated by consensus as shockable (1154, 303 patients) or nonshockable (4659, 841 patients). Segments during asystole were used to characterize the LDB artefact and to compare its characteristics to those of manual artefacts from other datasets. LDB artefacts were removed using adaptive filters. A machine learning algorithm was designed for the shock decision after filtering, and its performance was compared to that of a commercial defibrillator's algorithm.

RESULTS

Median (90% confidence interval) compression frequencies were lower and more stable for the LDB than for the manual artefact, 80 min^-1 (79.9-82.9) vs. 104.4 min^-1 (48.5-114.0). The amplitude and waveform regularity (Pearson's correlation coefficient) were larger for the LDB artefact, with 5.5 mV (0.8-23.4) vs. 0.5 mV (0.1-2.2) (p < 0.001) and 0.99 (0.78-1.0) vs. 0.88 (0.55-0.98) (p < 0.001). The shock decision accuracy was significantly higher for the machine learning algorithm than for the defibrillator algorithm, with sensitivity/specificity pairs of 92.1/96.8% (machine learning) vs. 91.4/87.1% (defibrillator) (p < 0.001).

CONCLUSION

Compared to other cardiopulmonary resuscitation artefacts, removing the LDB artefact was challenging due to larger amplitudes and lower compression frequencies. The machine learning algorithm achieved clinically reliable shock decisions during LDB compressions.

Shoulder strap fixation of LUCAS-2 to facilitate continuous CPR during non-supine (stair) stretcher transport of OHCAs patients

Early recognition and rapid initiation of high-quality cardiopulmonary resuscitation (CPR) are key to maximising chances of achieving successful return of spontaneous circulation in patients with out-of-hospital cardiac arrests (OHCAs), as well as improving patient outcomes both inside and outside hospital. Mechanical chest compression devices such as the LUCAS-2 have been developed to assist rescuers in providing consistent, high-quality compressions, even during transportation. However, providing uninterrupted and effective compressions with LUCAS-2 during transportation down stairwells and in tight spaces in a non-supine position is relatively impossible. In this study, we proposed adaptations to the LUCAS-2 to allow its use during transportation down stairwells and examined its effectiveness in providing high-quality CPR to simulated OHCA patients. 20 volunteer emergency medical technicians were randomised into 10 pairs, each undergoing 2 simulation runs per experimental arm (LUCAS-2 versus control) with a loaded Resusci Anne First Aid full body manikin weighing 60 kg. Quality of CPR compressions performed was measured using the CPRmeter placed on the sternum of the manikin. The respective times taken for each phase of the simulation protocol were recorded. Fisher’s exact tests were used to analyse categorical variables and median test to analyse continuous variables. The LUCAS-2 group required a longer time (~ 35 s) to prepare the patient prior to transport (p < 0.0001) and arrive at the ambulance (p < 0.0001) compared to the control group. The CPR quality in terms of depth and rate for the overall resuscitation period did not differ significantly between the LUCAS-2 group and control group, though there was a reduction in both parameters when evaluating the device’s automated compressions during transport. Nevertheless, the application of the LUCAS-2 device yielded a significantly higher chest compression fraction of 0.76 (p < 0.0001). Our novel adaptations to the LUCAS-2 device allow for uninterrupted compressions in patients being transported down stairwells, thus yielding better chest compression fractions for the overall resuscitation period. Whether potentially improved post-OHCA survival rates may be achieved requires confirmation in a real-world scenario study.

End-Tidal Carbon Dioxide Impacts Brain and Kidney Injury in Experimental Extracorporeal Cardiopulmonary Resuscitation (ECPR)

PURPOSE

Extracorporeal membrane oxygenation-assisted cardiopulmonary resuscitation (ECPR) is proposed for cardiac resuscitation in selected cases. End-tidal carbon dioxide (ETCO2) is easily obtained during conventional cardiopulmonary resuscitation (CPR). We hypothesized that the level of ETCO2 during CPR would reflect the degree of brain and kidney damage following ECPR in experimental refractory cardiac arrest.

METHODS

Ventricular fibrillation was induced in 10 pigs, followed by mechanical CPR for 45 min and thereafter ECPR for 180 min. Blood- and urine-samples, physiologic parameters, and histopathology of brain and kidney were analyzed. Animals were divided into Group High (GHigh) and Group Low (GLow) according to value of ETCO2 (10 mm Hg) at the end of CPR.

RESULTS

Carotid blood pressure and blood flow declined over time in both groups during CPR but was higher in GHigh. Coefficient of determination for ETCO2 and carotid blood flow was substantial (r2 = 0.62). The oxygen delivery index was higher for GHigh 444 (396-485) L/min/m2 as compared with GLow at 343 (327-384) L/min/m2 (P = 0.02) at the end of ECPR. Also, P-S100B were lower in GHigh, (P < 0.05) and GLow demonstrated worse histopathological injury in central parts of the brain (P < 0.01). During ECPR, urinary output was higher in GHigh (P < 0.05). Kidney injury marker Plasma Neutrophil Gelatinae-associated Lipocalin increased in both groups during ECPR but was more pronounced in GLow (P = 0.03). Renal histopathology revealed no difference between groups.

CONCLUSIONS

ETCO2 at the end of mechanical CPR is inversely associated with extent of brainstem and renal injury following ECPR.

Automated mechanical cardiopulmonary resuscitation devices versus manual chest compressions in the treatment of cardiac arrest: protocol of a systematic review and meta-analysis comparing machine to human

INTRODUCTION

Cardiac arrest is a leading cause of death in industrialised countries. Cardiopulmonary resuscitation (CPR) guidelines follow the principles of closed chest compression as described for the first time in 1960. Mechanical CPR devices are designed to improve chest compression quality, thus considering the improvement of resuscitation outcomes. This protocol outlines a systematic review and meta-analysis methodology to assess trials investigating the therapeutic effect of automated mechanical CPR devices at the rate of return of spontaneous circulation, neurological state and secondary endpoints (including short-term and long-term survival, injuries and surrogate parameters for CPR quality) in comparison with manual chest compressions in adults with cardiac arrest.

METHODS AND ANALYSIS

A sensitive search strategy will be employed in established bibliographic databases from inception until the date of search, followed by forward and backward reference searching. We will include randomised and quasi-randomised trials in qualitative analysis thus comparing mechanical to manual CPR. Studies reporting survival outcomes will be included in quantitative analysis. Two reviewers will assess independently publications using a predefined data collection form. Standardised tools will be used for data extraction, risks of bias and quality of evidence. If enough studies are identified for meta-analysis, the measures of association will be calculated by dint of bivariate random-effects models. Statistical heterogeneity will be evaluated by I²-statistics and explored through sensitivity analysis. By comprehensive subgroup analysis we intend to identify subpopulations who may benefit from mechanical or manual CPR techniques. The reporting follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

ETHICS AND DISSEMINATION

No ethical approval will be needed because data from previous studies will be retrieved and analysed. Most resuscitation studies are conducted under an emergency exception for informed consent. This publication contains data deriving from a dissertation project. We will disseminate the results through publication in a peer-reviewed journal and at scientific conferences.

PROSPERO REGISTRATION NUMBER

CRD42017051633.

Randomized blinded trial of automated REBOA during CPR in a porcine model of cardiac arrest

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) reportedly elevates arterial blood pressure (ABP) during non-traumatic cardiac arrest.

OBJECTIVES

This randomized, blinded trial of cardiac arrest in pigs evaluated the effect of automated REBOA two minutes after balloon inflation on ABP (primary endpoint) as well as arterial blood gas values and markers of cerebral haemodynamics and metabolism.

METHODS

Twenty anesthetized pigs were randomized to REBOA inflation or sham-inflation (n = 10 in each group) followed by insertion of invasive monitoring and a novel, automated REBOA catheter (NEURESCUE® Catheter & NEURESCUE® Assistant). Cardiac arrest was induced by ventricular pacing. Cardiopulmonary resuscitation was initiated three min after cardiac arrest, and the automated REBOA was inflated or sham-inflated (blinded to the investigators) five min after cardiac arrest.

RESULTS

In the inflation compared to the sham group, mean ABP above the REBOA balloon after inflation was higher (inflation: 54 (95%CI: 43-65) mmHg; sham: 44 (33-55) mmHg; P = 0.06), and diastolic ABP was higher (inflation: 38 (29-47) mmHg; sham: 26 (20-33) mmHg; P = 0.02), and the arterial to jugular oxygen content difference was lower (P = 0.04). After return of spontaneous circulation, mean ABP (inflation: 111 (95%CI: 94-128) mmHg; sham: 94 (95%CI: 65-123) mmHg; P = 0.04), diastolic ABP (inflation: 95 (95%CI: 78-113) mmHg; sham: 78 (95%CI: 50-105) mmHg; P = 0.02), CPP (P = 0.01), and brain tissue oxygen tension (inflation: 315 (95%CI: 139-491)% of baseline; sham: 204 (95%CI: 75-333)%; P = 0.04) were higher in the inflation compared to the sham group.

CONCLUSION

Inflation of REBOA in a porcine model of non-traumatic cardiac arrest improves central diastolic arterial pressure as a surrogate marker of coronary artery pressure, and cerebral perfusion.

INSTITUTIONAL PROTOCOL NUMBER

2017-15-0201-01371.

Use of Capnography and Cardiopulmonary Resuscitation Feedback Devices Among Prehospital Advanced Life Support Providers

BACKGROUND

Capnography and cardiopulmonary resuscitation (CPR) feedback devices have been shown to improve resuscitation outcomes, with the American Heart Association recommending their use during advanced life support (ALS). Little is known about the availability of these devices, their protocoled use, and the attitudes toward them in the prehospital setting.

OBJECTIVES

The objectives of this study were to assess the availability of capnography and CPR feedback devices among prehospital ALS agencies in New York State (NYS), to describe the protocoled use of these devices, and to evaluate the attitudes of providers toward the use of these devices.

METHODS

Prehospital agencies that provide ALS services in NYS were identified using an online registry. Managers in these agencies were contacted by electronic mail and asked to complete a questionnaire regarding their agency's experience with capnography and CPR feedback devices. The questionnaire included questions on the availability of capnography and CPR feedback devices, the existence of clinical protocols for using capnography, and provider opinion on the utility of capnography and CPR feedback devices for improving pediatric resuscitation.

RESULTS

Of 710 ALS agencies, 238 (33.5%) completed the survey. Ninety-five percent and 24% of agencies reported having capnography and CPR feedback devices available aboard ambulances, respectively. Ninety-seven percent of agencies reported having capnography clinical protocols for endotracheal intubation, 63% for return of spontaneous circulation, and 54% for guiding CPR. Forty-seven percent agreed that capnography improves outcomes in the resuscitation of pediatric patients, whereas 51% of providers were neutral and 2% disagreed.

CONCLUSIONS

Capnography is available in most NYS ALS agencies surveyed. Cardiopulmonary resuscitation feedback devices are less common. Protocols for the use of capnography mainly focused on endotracheal intubation and less for the recognition of return of spontaneous circulation and for guiding CPR. Half of the providers surveyed were neutral on whether capnography improves outcomes in the resuscitation of pediatric patients.

Skeletal and soft tissue injuries after manual and mechanical chest compressions

AIMS

To determine the rate of injuries related to cardiopulmonary resuscitation (CPR) in cardiac arrest non-survivors, comparing manual CPR with CPR performed using the Lund University Cardiac Assist System (LUCAS).

METHODS AND RESULTS

We prospectively evaluated 414 deceased adult patients using focused, standardized post-mortem investigation in years 2005 through 2013. Skeletal and soft tissue injuries were noted, and soft tissue injuries were evaluated with respect to degree of severity. We found sternal fracture in 38%, rib fracture in 77%, and severe soft tissue injury in 1.9% of cases treated with CPR with manual chest compressions (n = 52). Treatment with LUCAS CPR (n = 362) was associated with significantly higher rates of sternal fracture (80% of cases), rib fracture (96%), and severe soft tissue injury (10%), including several cases of potentially life-threatening injuries.

CONCLUSION

LUCAS CPR causes significantly more CPR-related injuries than manual CPR, while providing no proven survival benefit on a population basis. We suggest judicious use of the LUCAS device for cardiac arrest.

Study of the Effects of 3 h of Continuous Cardiopulmonary Resuscitation at 27°C on Global Oxygen Transport and Organ Blood Flow

Aims

Complete restitution of neurologic function after 6 h of pre-hospital resuscitation and in-hospital rewarming has been reported in accidental hypothermia patients with cardiac arrest (CA). However, the level of restitution of circulatory function during long-lasting hypothermic cardiopulmonary resuscitation (CPR) remains largely unknown. We compared the effects of CPR in replacing spontaneous circulation during 3 h at 27°C vs. 45 min at normothermia by determining hemodynamics, global oxygen transport (DO₂), oxygen uptake (VO₂), and organ blood flow.

Methods

Anesthetized pigs (n = 7) were immersion cooled to CA at 27°C. Predetermined variables were compared: (1) Before cooling, during cooling to 27°C with spontaneous circulation, after CA and subsequent continuous CPR (n = 7), vs. (2) before CA and during 45 min CPR in normothermic pigs (n = 4).

Results

When compared to corresponding values during spontaneous circulation at 38°C: (1) After 15 min of CPR at 27°C, cardiac output (CO) was reduced by 74%, mean arterial pressure (MAP) by 63%, DO₂ by 47%, but organ blood flow was unaltered. Continuous CPR for 3 h maintained these variables largely unaltered except for significant reduction in blood flow to the heart and brain after 3 h, to the kidneys after 1 h, to the liver after 2 h, and to the stomach and small intestine after 3 h. (2) After normothermic CPR for 15 min, CO was reduced by 71%, MAP by 54%, and DO₂ by 63%. After 45 min, hemodynamic function had deteriorated significantly, organ blood flow was undetectable, serum lactate increased by a factor of 12, and mixed venous O₂ content was reduced to 18%.

Conclusion

The level to which CPR can replace CO and MAP during spontaneous circulation at normothermia was not affected by reduction in core temperature in our setting. Compared to spontaneous circulation at normothermia, 3 h of continuous resuscitation at 27°C provided limited but sufficient O₂ delivery to maintain aerobic metabolism. This fundamental new knowledge is important in that it encourages early and continuous CPR in accidental hypothermia victims during evacuation and transport.

Coronary Artery and Right Ventricular Perforation Due to Mechanical CPR Trauma

Mechanical cardiopulmonary resuscitation (CPR) devices provide consistent, high-quality CPR but have been associated with a risk of visceral organ injury. However, these devices are used when traditional CPR is logistically difficult, such as during primary percutaneous coronary intervention. The following patient case illustrates mechanical CPR device use resulting in ventricular and coronary artery injury. (Level of Difficulty: Intermediate.)

Prolonged cardiopulmonary resuscitation and low flow state are not contraindications for extracorporeal support

Outcomes of out-of-hospital cardiac arrest are poor irrespective of the patient age group and circumstances. Survival to discharge after out-of-hospital arrest in children is less than 10%. Use of extracorporeal cardiopulmonary resuscitation is increasing and has been shown to improve outcomes in some situations. However, the candidacy for such augmentation is based on patient selection, institutional practices, and availability of an extracorporeal membrane oxygenation center. Often, duration of resuscitation, low flow state, presenting pH, and circumstances of arrest dictate candidacy for extracorporeal membrane oxygenation. We present a case of extremely prolonged resuscitation for out-of-hospital arrest in a pediatric patient, and we describe the use of mechanical compression device and transition to extracorporeal membrane oxygenation. We present the case outcome as well as brief discussion about controversies in extracorporeal cardiopulmonary resuscitation. We hope the case provides an opportunity for further discussion regarding opportunities to improve selection, use of extracorporeal cardiopulmonary resuscitation, and impact outcomes.

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.

An observational study on survival rates of patients with out-of-hospital cardiac arrest in the Netherlands after improving the 'chain of survival'

OBJECTIVES

To evaluate the impact of implemented procedures for out-of-hospital cardiac arrests (OHCAs) by determining patient outcome defined as the percentage return of spontaneous circulation at arrival at the emergency department, and 3-month and 1-year-survival rates.

DESIGN

Observational study.

SETTING

Primary emergency medical care consisting of Advanced Life Support is given by ambulance nurses and secondary care by hospitals within the mid-western part of the Netherlands covering 750 000 inhabitants.

PARTICIPANTS

433 of 500 consecutive patients with OHCA were included in the study over a 1.5 -year period.

OUTCOME MEASURES

Analysis included number of patients with return of spontaneous circulation (ROSC) when handed over to the emergency department, survival at 3 months and 1 year including a comparison with global outcome rates. We further considered the influence of gender, delays, bystander Basic Life Support, use of an automated external defibrillator, initial rhythm and mechanical thorax compression in combination with Boussignac tube ventilation.

RESULTS

13% (67/500) of the initial patient population was excluded from the analysis as reanimation in these patients was aborted due to expressed wish not to be resuscitated. Resuscitation was started by bystanders, police and/or first responders in 312/433 (72%) cases. An automated external defibrillator was used in 198 of these 312 cases (63%) of which it defibrillated 108 times. Mechanical thorax compression in combination with Boussignac tube ventilation was necessary in 277/433 patients (64%). Spontaneous circulation returned in 96/277 (35%) patients of this group. In the overall studied population, ROSC percentage at arrival at the hospital was 214/433 (49%). The 3-month and 12-month-survival rates were 123/433 (28%) and 119/433 (27%), respectively.

CONCLUSIONS

Optimised 'chain of survival' for patients with OHCA resulted in ROSC in 49% of the cases and a 1-year-survival rate of 27% in the studied population.

Continuous chest compressions with a simultaneous triggered ventilator in the Munich Emergency Medical Services: a case series

Background: Mechanical chest compression devices are commonly used providing a constant force and frequency of chest compression during cardiopulmonary resuscitation. However, there are currently no recommendations on ventilation during cardiopulmonary resuscitation with a mechanical chest compression device using continuous mode. An effective method for ventilation in such scenarios might be a triggered oxygen-powered resuscitator. Methods: We report seven cardiopulmonary resuscitation cases from the Munich Emergency Medical Service where mechanical chest compression devices in continuous mode were used with an oxygen-powered resuscitator. In each case, the resuscitator (Oxylator®) was running in automatic mode delivering a breath during the decompression phase of the chest compressions at a frequency of 100 per minute. End-tidal carbon dioxide and pulse oximetry were measured. Additional data was collected from the resuscitation protocol of each patient. Results: End-tidal carbon dioxide was available in all cases while oxygen saturation only in four. Five patients had a return of spontaneous circulation. Based on the end-tidal carbon dioxide values of each of the cases, the resuscitator did not seem to cause hyperventilation and suggests that good-quality cardiopulmonary resuscitation was delivered. Conclusions: Continuous chest compressions using a mechanical chest compression device and simultaneous synchronized ventilation using an oxygen-powered resuscitator in an automatic triggering mode might be feasible during cardiopulmonary resuscitation.

Confirming the Clinical Safety and Feasibility of a Bundled Methodology to Improve Cardiopulmonary Resuscitation Involving a Head-Up/Torso-Up Chest Compression Technique

OBJECTIVES

Combined with devices that enhance venous return out of the brain and into the thorax, preclinical outcomes are improved significantly using a synergistic bundled approach involving mild elevation of the head and chest during cardiopulmonary resuscitation. The objective here was to confirm clinical safety/feasibility of this bundled approach including use of mechanical cardiopulmonary resuscitation provided at a head-up angle.

DESIGN

Quarterly tracking of the frequency of successful resuscitation before, during, and after the clinical introduction of a bundled head-up/torso-up cardiopulmonary resuscitation strategy.

SETTING

9-1-1 response system for a culturally diverse, geographically expansive, populous jurisdiction.

PATIENTS

All 2,322 consecutive out-of-hospital cardiac arrest cases (all presenting cardiac rhythms) were followed over 3.5 years (January 1, 2014, to June 30, 2017).

INTERVENTIONS

In 2014, 9-1-1 crews used LUCAS (Physio-Control Corporation, Redmond, WA) mechanical cardiopulmonary resuscitation and impedance threshold devices for out-of-hospital cardiac arrest. After April 2015, they also 1) applied oxygen but deferred positive pressure ventilation several minutes, 2) solidified a pit-crew approach for rapid LUCAS placement, and 3) subsequently placed the patient in a reverse Trendelenburg position (~20°).

MEASUREMENTS AND MAIN RESULTS

No problems were observed with head-up/torso-up positioning (n = 1,489), but resuscitation rates rose significantly during the transition period (April to June 2015) with an ensuing sustained doubling of those rates over the next 2 years (mean, 34.22%; range, 29.76-39.42%; n = 1,356 vs 17.87%; range, 14.81-20.13%, for 806 patients treated prior to the transition; p < 0.0001). Outcomes improved across all subgroups. Response intervals, clinical presentations and indications for attempting resuscitation remained unchanged. Resuscitation rates in 2015-2017 remained proportional to neurologically intact survival (~35-40%) wherever tracked.

CONCLUSIONS

The head-up/torso-up cardiopulmonary resuscitation bundle was feasible and associated with an immediate, steady rise in resuscitation rates during implementation followed by a sustained doubling of the number of out-of-hospital cardiac arrest patients being resuscitated. These findings make a compelling case that this bundled technique will improve out-of-hospital cardiac arrest outcomes significantly in other clinical evaluations.

Does endotracheal intubation increases chest compression fraction in out of hospital cardiac arrest: A substudy of the CAAM trial

BACKGROUND

Optimal out of hospital cardiac arrest (OHCA) airway management strategies remain unclear. We compared chest compression fraction (CCF) between patients receiving endotracheal intubation (ETI) versus bag mask ventilation (BMV).

METHODS

We studied adult OHCA enrolled from our center in the CAAM trial. Primary exposures were ETI or BMV. Primary outcome was whole intervention CCF, adjusted for Utstein confounders. Secondary outcomes were per cycle CCF, no flow time associated (NFT) with ventilation, rhythms checks and mechanical chest compression device placement.

RESULTS

Of 2040 OHCA enrolled in the CAAM trial we analyzed 112 cases recruited by our center. Unadjusted CCF was 0.89 for ETI and 0.88 for BMV (p = 0.19). Compared with BMV, ETI achieved lower NFT associated with ventilations (32 vs 127 s; p < 0.001). ETI cases experienced higher NFT associated with rhythm checks (69.5 vs 42.5 s p = 0.02) and with mechanical chest compression placement (29 vs 20 s; p = 0.04). CCF was higher during the first cycle in BMV than in ETI patients (0.81 vs 0.74; p = 0.02). After correction for confounders we observed no difference in global intervention CCF between the ETI and BMV (ΔCCF [ETI-BMV] 0.301; [95%CI: -1.9 to 2.51]; p = 0.79).

CONCLUSION

In our substudy whole intervention CCF among OHCA was not modified by ETI compared to BMV. In the ETI group we observed lower NFT associated with ventilations and higher NFT associated with mechanical chest compression devices placement. CCF was lower in the ETI group during the first cycle.

Controversial Issues: Pro Mechanical Cardiopulmonary Resuscitation

High-quality cardiopulmonary resuscitation, in particular chest compressions, is a key aspect of out-of-hospital cardiac arrest (OHCA) resuscitation. Manual chest compressions remain the standard of care; however, the extrication and transport of patients with OHCA undermine the quality of manual chest compressions and risk the safety of paramedics. Therefore, in circumstances whereby high-quality manual chest compressions are difficult or unsafe, paramedics should consider using a mechanical device. By combining high-quality manual chest compressions and judicious application of mechanical chest compressions, emergency medical service agencies can optimize paramedic safety and patient outcomes.

Mechanical versus manual chest compressions for cardiac arrest

BACKGROUND

Mechanical chest compression devices have been proposed to improve the effectiveness of cardiopulmonary resuscitation (CPR).

OBJECTIVES

To assess the effectiveness of resuscitation strategies using mechanical chest compressions versus resuscitation strategies using standard manual chest compressions with respect to neurologically intact survival in patients who suffer cardiac arrest.

SEARCH METHODS

On 19 August 2017 we searched the Cochrane Central Register of Controlled Studies (CENTRAL), MEDLINE, Embase, Science Citation Index-Expanded (SCI-EXPANDED) and Conference Proceedings Citation Index-Science databases. Biotechnology and Bioengineering Abstracts and Science Citation abstracts had been searched up to November 2009 for prior versions of this review. We also searched two clinical trials registries for any ongoing trials not captured by our search of databases containing published works: Clinicaltrials.gov (August 2017) and the World Health Organization International Clinical Trials Registry Platform portal (January 2018). We applied no language restrictions. We contacted experts in the field of mechanical chest compression devices and manufacturers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), cluster-RCTs and quasi-randomised studies comparing mechanical chest compressions versus manual chest compressions during CPR for patients with cardiac arrest.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included five new studies in this update. In total, we included 11 trials in the review, including data from 12,944 adult participants, who suffered either out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA). We excluded studies explicitly including patients with cardiac arrest caused by trauma, drowning, hypothermia and toxic substances. These conditions are routinely excluded from cardiac arrest intervention studies because they have a different underlying pathophysiology, require a variety of interventions specific to the underlying condition and are known to have a prognosis different from that of cardiac arrest with no obvious cause. The exclusions were meant to reduce heterogeneity in the population while maintaining generalisability to most patients with sudden cardiac death.The overall quality of evidence for the outcomes of included studies was moderate to low due to considerable risk of bias. Three studies (N = 7587) reported on the designated primary outcome of survival to hospital discharge with good neurologic function (defined as a Cerebral Performance Category (CPC) score of one or two), which had moderate quality evidence. One study showed no difference with mechanical chest compressions (risk ratio (RR) 1.07, 95% confidence interval (CI) 0.82 to 1.39), one study demonstrated equivalence (RR 0.79, 95% CI 0.60 to 1.04), and one study demonstrated reduced survival (RR 0.41, CI 0.21 to 0.79). Two other secondary outcomes, survival to hospital admission (N = 7224) and survival to hospital discharge (N = 8067), also had moderate quality level of evidence. No studies reported a difference in survival to hospital admission. For survival to hospital discharge, two studies showed benefit, four studies showed no difference, and one study showed harm associated with mechanical compressions. No studies demonstrated a difference in adverse events or injury patterns between comparison groups but the quality of data was low. Marked clinical and statistical heterogeneity between studies precluded any pooled estimates of effect.

AUTHORS' CONCLUSIONS

The evidence does not suggest that CPR protocols involving mechanical chest compression devices are superior to conventional therapy involving manual chest compressions only. We conclude on the balance of evidence that mechanical chest compression devices used by trained individuals are a reasonable alternative to manual chest compressions in settings where consistent, high-quality manual chest compressions are not possible or dangerous for the provider (eg, limited rescuers available, prolonged CPR, during hypothermic cardiac arrest, in a moving ambulance, in the angiography suite, during preparation for extracorporeal CPR [ECPR], etc.). Systems choosing to incorporate mechanical chest compression devices should be closely monitored because some data identified in this review suggested harm. Special attention should be paid to minimising time without compressions and delays to defibrillation during device deployment.

Does use of the LUCAS device improve mortality in adult patients with out-of-hospital cardiac arrest?

Out-of-hospital cardiac arrest (OHCA) is a common occurrence in the UK, with 60,000 cases reported annually. To improve outcomes among these patients it is necessary to improve links in the cardiac arrest chain of survival. Cardiopulmonary resuscitation (CPR) is one of the main elements of this chain because it reduces further ischaemic insult in the brain and heart by contributing to blood flow. However, even the best manual CPR provides only 20%-30% of the normal cardiac output. Despite the emphasis on timely CPR at the correct rate and depth, delivery of compressions is suboptimal for many patients and mechanical devices may improve outcomes. This article critically appraises two important papers on the use of mechanical CPR for OHCA. It also suggests potential uses for this treatment option and areas for future research.

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.

Military application of mechanical CPR devices: a pressing requirement?

Maintaining high-quality chest compressions during cardiopulmonary resuscitation following cardiac arrest presents a challenge. The currently available mechanical CPR (mCPR) devices are described in this review, coupled with an analysis of the evidence pertaining to their efficacy. Overall, mCPR appears to be at least equivalent to high-quality manual CPR in large trials. There is potential utility for mCPR devices in the military context to ensure uninterrupted quality CPR following a medical cardiac arrest. Particular utility may be in a prohibitive operational environment, where manpower is limited or where timelines to definitive care are stretched resulting in a requirement for prolonged resuscitation. mCPR can also act as a bridge to advanced endovascular resuscitation techniques should they become more mainstream therapy.

Prehospital randomised assessment of a mechanical compression device in out-of-hospital cardiac arrest (PARAMEDIC): a pragmatic, cluster randomised trial and economic evaluation

BACKGROUND

Mechanical chest compression devices may help to maintain high-quality cardiopulmonary resuscitation (CPR), but little evidence exists for their effectiveness. We evaluated whether or not the introduction of Lund University Cardiopulmonary Assistance System-2 (LUCAS-2; Jolife AB, Lund, Sweden) mechanical CPR into front-line emergency response vehicles would improve survival from out-of-hospital cardiac arrest (OHCA).

OBJECTIVE

Evaluation of the LUCAS-2 device as a routine ambulance service treatment for OHCA.

DESIGN

Pragmatic, cluster randomised trial including adults with non-traumatic OHCA. Ambulance dispatch staff and those collecting the primary outcome were blind to treatment allocation. Blinding of the ambulance staff who delivered the interventions and reported initial response to treatment was not possible. We also conducted a health economic evaluation and a systematic review of all trials of out-of-hospital mechanical chest compression.

SETTING

Four UK ambulance services (West Midlands, North East England, Wales and South Central), comprising 91 urban and semiurban ambulance stations. Clusters were ambulance service vehicles, which were randomly assigned (approximately 1 : 2) to the LUCAS-2 device or manual CPR.

PARTICIPANTS

Patients were included if they were in cardiac arrest in the out-of-hospital environment. Exclusions were patients with cardiac arrest as a result of trauma, with known or clinically apparent pregnancy, or aged < 18 years.

INTERVENTIONS

Patients received LUCAS-2 mechanical chest compression or manual chest compressions according to the first trial vehicle to arrive on scene.

MAIN OUTCOME MEASURES

Survival at 30 days following cardiac arrest; survival without significant neurological impairment [Cerebral Performance Category (CPC) score of 1 or 2].

RESULTS

We enrolled 4471 eligible patients (1652 assigned to the LUCAS-2 device and 2819 assigned to control) between 15 April 2010 and 10 June 2013. A total of 985 (60%) patients in the LUCAS-2 group received mechanical chest compression and 11 (< 1%) patients in the control group received LUCAS-2. In the intention-to-treat analysis, 30-day survival was similar in the LUCAS-2 (104/1652, 6.3%) and manual CPR groups [193/2819, 6.8%; adjusted odds ratio (OR) 0.86, 95% confidence interval (CI) 0.64 to 1.15]. Survival with a CPC score of 1 or 2 may have been worse in the LUCAS-2 group (adjusted OR 0.72, 95% CI 0.52 to 0.99). No serious adverse events were noted. The systematic review found no evidence of a survival advantage if mechanical chest compression was used. The health economic analysis showed that LUCAS-2 was dominated by manual chest compression.

LIMITATIONS

There was substantial non-compliance in the LUCAS-2 arm. For 272 out of 1652 patients (16.5%), mechanical chest compression was not used for reasons that would not occur in clinical practice. We addressed this issue by using complier average causal effect analyses. We attempted to measure CPR quality during the resuscitation attempts of trial participants, but were unable to do so.

CONCLUSIONS

There was no evidence of improvement in 30-day survival with LUCAS-2 compared with manual compressions. Our systematic review of recent randomised trials did not suggest that survival or survival without significant disability may be improved by the use of mechanical chest compression.

FUTURE WORK

The use of mechanical chest compression for in-hospital cardiac arrest, and in specific circumstances (e.g. transport), has not yet been evaluated.

TRIAI REGISTRATION

Current Controlled Trials ISRCTN08233942.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 11. See the NIHR Journals Library website for further project information.

Addition of Audiovisual Feedback During Standard Compressions Is Associated with Improved Ability

Introduction

A benefit of in-hospital cardiac arrest is the opportunity for rapid initiation of “high-quality” chest compressions as defined by current American Heart Association (AHA) adult guidelines as a depth 2–2.4 inches, full chest recoil, rate 100–120 per minute, and minimal interruptions with a chest compression fraction (CCF) ≥ 60%. The goal of this study was to assess the effect of audiovisual feedback on the ability to maintain high-quality chest compressions as per 2015 updated guidelines.

Methods

Ninety-eight participants were randomized into four groups. Participants were randomly assigned to perform chest compressions with or without use of audiovisual feedback (+/− AVF). Participants were further assigned to perform either standard compressions with a ventilation ratio of 30:2 to simulate cardiopulmonary resuscitation (CPR) without an advanced airway or continuous chest compressions to simulate CPR with an advanced airway. The primary outcome measured was ability to maintain high-quality chest compressions as defined by current 2015 AHA guidelines.

Results

Overall comparisons between continuous and standard chest compressions (n=98) were without significant differences in chest compression dynamics (p’s >0.05). Overall comparisons between +/− AVF (n = 98) were significant for differences in average rate of compressions per minute (p= 0.0241) and proportion of chest compressions within guideline rate recommendations (p = 0.0084). There was a significant difference in the proportion of high quality-chest compressions favoring AVF (p = 0.0399). Comparisons between chest compression strategy groups +/− AVF were significant for differences in compression dynamics favoring AVF (p’s < 0.05).

Conclusion

Overall, AVF is associated with greater ability to maintain high-quality chest compressions per most-recent AHA guidelines. Specifically, AVF was associated with a greater proportion of compressions within ideal rate with standard chest compressions while demonstrating a greater proportion of compressions with simultaneous ideal rate and depth with a continuous compression strategy.

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.

Mechanical Cardiopulmonary Resuscitation Device in an Accident and Emergency Department: A Case Report and Literature Review

We present a case of resuscitation of a 38-year-old lady with ventricular fibrillation using the Lund University Cardiopulmonary Assist System (LUCAS), a mechanical cardiopulmonary resuscitation (CPR) device. Return of spontaneous circulation was obtained after prolonged resuscitation but the patient eventually succumbed nine days after admission to the coronary care unit. The role of mechanical CPR devices in resuscitation in the accident and emergency department is discussed.

Post-admission outcomes of participants in the PARAMEDIC trial: A cluster randomised trial of mechanical or manual chest compressions

BACKGROUND

The PARAMEDIC cluster randomised trial evaluated the LUCAS mechanical chest compression device, and did not find evidence that use of mechanical chest compression led to an improvement in survival at 30 days. This paper reports patient outcomes from admission to hospital to 12 months after randomisation.

METHODS

Information about hospital length of stay and intensive care management was obtained through linkage with Hospital Episode Statistics and the Intensive Care National Audit and Research Centre. Patients surviving to hospital discharge were approached to complete questionnaires (SF-12v2, EQ-5D, MMSE, HADS and PTSD-CL) at 90days and 12 months. The study is registered with Current Controlled Trials, number ISRCTN08233942.

RESULTS

377 patients in the LUCAS arm and 658 patients in the manual chest compression were admitted to hospital. Hospital and intensive care length of stay were similar. Long term follow-up assessments were limited by poor response rates (53.7% at 3 months and 55.6% at 12 months). Follow-up rates were lower in those with worse neurological function. Among respondents, long term health related quality of life outcomes and emotional well-being was similar between groups. Cognitive function, measured by MMSE, was marginally lower in the LUCAS arm mean 26.9 (SD 3.7) compared to control mean 28.0 (SD 2.3), adjusted mean difference -1.5 (95% CI -2.6 to -0.4).

CONCLUSION

There were no clinically important differences identified in outcomes at long term follow-up between those allocated to the mechanical chest compression compared to those receiving manual chest compression.

Improving CPR Performance

Cardiac arrest continues to represent a public health burden with most patients having dismal outcomes. CPR is a complex set of interventions requiring leadership, coordination, and best practices. Despite the widespread adoption of new evidence in various guidelines, the provision of CPR remains variable with poor adherence to published recommendations. Key steps health-care systems can take to enhance the quality of CPR and, potentially, to improve outcomes, include optimizing chest compressions, avoiding hyperventilation, encouraging intraosseous access, and monitoring capnography. Feedback devices provide instantaneous guidance to the rescuer, improve rescuer technique, and could impact patient outcomes. New technologies promise to improve the resuscitation process: mechanical devices standardize chest compressions, capnography guides resuscitation efforts and signals the return of spontaneous circulation, and intraosseous devices minimize interruptions to gain vascular access. This review aims at identifying a discreet group of interventions that health-care systems can use to raise their standard of cardiac resuscitation.

Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

BACKGROUND

This paper provides an up-to-date review of the management and outcome of accidental hypothermia patients with and without cardiac arrest.

METHODS

The authors reviewed the relevant literature in their specialist field. Summaries were merged, discussed and approved to produce this narrative review.

RESULTS

The hospital use of minimally-invasive rewarming for non-arrested, otherwise healthy, patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionised the management of hypothermic cardiac arrest, with survival rates approaching 100 % in some cases. Hypothermic patients with risk factors for imminent cardiac arrest (temperature <28 °C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS-centre. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanical CPR can be helpful. Delayed or intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern post-resuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimise pre-hospital triage, transport and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and post-resuscitation care.

CONCLUSIONS

Based on new evidence, additional clinical experience and clearer management guidelines and documentation, the treatment of accidental hypothermia has been refined. ECLS has substantially improved survival and is the treatment of choice in the patient with unstable circulation or cardiac arrest.

Cardiopulmonary Resuscitation Pattern Evaluation Based on Ensemble Empirical Mode Decomposition Filter via Nonlinear Approaches

Good quality cardiopulmonary resuscitation (CPR) is the mainstay of treatment for managing patients with out-of-hospital cardiac arrest (OHCA). Assessment of the quality of the CPR delivered is now possible through the electrocardiography (ECG) signal that can be collected by an automated external defibrillator (AED). This study evaluates a nonlinear approximation of the CPR given to the asystole patients. The raw ECG signal is filtered using ensemble empirical mode decomposition (EEMD), and the CPR-related intrinsic mode functions (IMF) are chosen to be evaluated. In addition, sample entropy (SE), complexity index (CI), and detrended fluctuation algorithm (DFA) are collated and statistical analysis is performed using ANOVA. The primary outcome measure assessed is the patient survival rate after two hours. CPR pattern of 951 asystole patients was analyzed for quality of CPR delivered. There was no significant difference observed in the CPR-related IMFs peak-to-peak interval analysis for patients who are younger or older than 60 years of age, similarly to the amplitude difference evaluation for SE and DFA. However, there is a difference noted for the CI (p < 0.05). The results show that patients group younger than 60 years have higher survival rate with high complexity of the CPR-IMFs amplitude differences.

Mechanical chest compression devices are associated with poor neurological survival in a statewide registry: A propensity score analysis

OBJECTIVE

To compare functional survival (discharge cerebral performance category 1 or 2) among victims of out-of-hospital cardiac arrest (OHCA) who had resuscitations performed using mechanical chest compression (mech-CC) devices vs. those using manual chest compressions (man-CC).

METHODS

Observational cohort of 2600 cases of OHCA from a statewide, prospectively-collected cardiac arrest registry (Utah Cardiac Arrest Registry to Enhance Survival). Comparison of functional survival among those receiving mech-CC vs man-CC was performed using a mixed-effects Poisson model with inverse probability weighted propensity scores to control for selection bias.

RESULTS

Overall, mech-CC was utilized in 405/2600 (16%) of the total arrests in Utah during this period. 371/405 (92%) were of the load-distributing band type (AutoPulse(®)) and 22/405 (5%) were mechanical piston devices (LUCAS™), while 12/405 (3%) employed other devices. The relative risk (RR) for functional survival comparing mech-CC to man-CC after propensity score adjustment was 0.41 (95% CI 0.24-0.70, p=0.001).

CONCLUSIONS

Mechanical chest compression device use was associated with lower rates of functional survival in this propensity score analysis, controlling for Utstein variables and early return of spontaneous circulation.

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.

Are the current guideline recommendations for neonatal cardiopulmonary resuscitation safe and effective?

A recently published review of approaches to optimize chest compressions in the resuscitation of asphyxiated newborns discussed the current recommendations and explored potential determinants of effective neonatal cardiopulmonary resuscitation (CPR). However, not all potential determinants of effective neonatal CPR were explored. Chest compression shallower than the current guideline recommendation of approximately 33% of the anterior-posterior (AP) chest diameter may be safer and more effective. From a physiological standpoint, high-velocity brief duration shallower compression may be more effective than current recommendations. The application of a 1- or 2-finger method of high-impulse CPR, which would depend on the size of the subject, may be more effective than using a 2-thumb (TT) encircling hands method of CPR. Adrenaline should not be used in the treatment of asphyxiated neonates and when necessary titrated vasopressin should be used.