Chest wall mechanics during mechanical chest compression and its relationship to CPR-related injuries and survival

Aim To determine compression force variation (CFV) during mechanical cardiopulmonary resuscitation (CPR) and its relationship with CPR-related injuries and survival. Methods Adult non-traumatic OHCA patients who had been treated with mechanical CPR were evaluated for CPR-related injuries using chest X-rays, thoracic computed tomography or autopsy. The CFV exerted by the LUCAS 2 device was calculated as the difference between the maximum and the minimum force values and was categorised into three different groups (high positive CFV = 95 newton (N), high negative CFV = -95 N, and low variation for intermediate CFV). The CFV was correlated with the CPR injuries findings and survival data. Results Fifty-two patients were included. The median (IQR) age was 57 (49–66) years, and 13 (25%) cases survived until hospital admission. High positive CFV was found in 21 (40.4%) patients, high negative CFV in 9 (17.3%) and a low CFV in 22 (42.3%). The median (IQR) number of rib fractures was higher in the high positive and negative CFV groups compared with the low CFV group [7(1–9) and 9 (4–11) vs 0 (0–6) (p = 0.021)]. More bilateral fracture cases were found in the high positive and negative CFV groups [16 (76.2%) and 6 (66.7%) vs 6 (27.3%) (p = 0.004)]. In the younger half of the sample more patients survived until hospital admission in the low CFV group compared with the high CFV groups [5 (41.7%) vs 1 (7.1%) (p = 0.037)]. Conclusions High CFV was associated with ribcage injuries. In the younger patients low CFV was associated with survival until hospital admission.Peer ReviewedPostprint (published version

LUCAS Versus Manual Chest Compression During Ambulance Transport : A Hemodynamic Study in a Porcine Model of Cardiac Arrest

Background-Mechanical chest compression (CC) is currently suggested to deliver sustained high-quality CC in a moving ambulance. This study compared the hemodynamic support provided by a mechanical piston device or manual CC during ambulance transport in a porcine model of cardiopulmonary resuscitation. Methods and Results-In a simulated urban ambulance transport, 16 pigs in cardiac arrest were randomized to 18 minutes of mechanical CC with the LUCAS (n=8) or manual CC (n=8). ECG, arterial and right atrial pressure, together with end-tidal CO2 and transthoracic impedance curve were continuously recorded. Arterial lactate was assessed during cardiopulmonary resuscitation and after resuscitation. During the initial 3 minutes of cardiopulmonary resuscitation, the ambulance was stationary, while then proceeded along a predefined itinerary. When the ambulance was stationary, CC-generated hemodynamics were equivalent in the 2 groups. However, during ambulance transport, arterial and coronary perfusion pressure, and end-tidal CO(2 )were significantly higher with mechanical CC compared with manual CC (coronary perfusion pressure: 43 +/- 4 versus 18 +/- 4 mmHg; end-tidal CO2: 31 +/- 2 versus 19 +/- 2 mmHg, P Conclusions-This model adds evidence in favor of the use of mechanical devices to provide ongoing high-quality CC and tissue perfusion during ambulance transport.Peer reviewe

The Study Protocol for the LINC (LUCAS in Cardiac Arrest) Study: a study comparing conventional adult out-of-hospital cardiopulmonary resuscitation with a concept with mechanical chest compressions and simultaneous defibrillation

BACKGROUND: The LUCAS™ device delivers mechanical chest compressions that have been shown in experimental studies to improve perfusion pressures to the brain and heart as well as augmenting cerebral blood flow and end tidal CO(2,) compared with results from standard manual cardiopulmonary resuscitation (CPR). Two randomised pilot studies in out-of-hospital cardiac arrest patients have not shown improved outcome when compared with manual CPR. There remains evidence from small case series that the device can be potentially beneficial compared with manual chest compressions in specific situations. This multicentre study is designed to evaluate the efficacy and safety of mechanical chest compressions with the LUCAS™ device whilst allowing defibrillation during on-going CPR, and comparing the results with those of conventional resuscitation. METHODS/DESIGN: This article describes the design and protocol of the LINC-study which is a randomised controlled multicentre study of 2500 out-of-hospital cardiac arrest patients. The study has been registered at ClinicalTrials.gov (http://clinicaltrials.gov/ct2/show/NCT00609778?term=LINC&rank=1). RESULTS: Primary endpoint is four-hour survival after successful restoration of spontaneous circulation. The safety aspect is being evaluated by post mortem examinations in 300 patients that may reflect injuries from CPR. CONCLUSION: This large multicentre study will contribute to the evaluation of mechanical chest compression in CPR and specifically to the efficacy and safety of the LUCAS™ device when used in association with defibrillation during on-going CPR

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

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>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.</p> <p>Results</p> <p>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.</p> <p>Conclusion</p> <p>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.</p

Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs

BACKGROUND: The same mechanisms by which ultrasound enhances thrombolysis are described in connection with non-beneficial effects of ultrasound. The present safety study was therefore designed to explore effects of beneficial ultrasound characteristics on the infarcted and non-infarcted myocardium. METHODS: In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound of frequency 1 MHz and intensity 0.1 W/cm(2 )(I(SATA)) was applied during one hour to both infarcted and non-infarcted myocardial tissue. These ultrasound characteristics are similar to those used in studies of ultrasound enhanced thrombolysis. Using blinded assessment technique, myocardial damage was rated according to histopathological criteria. RESULTS: Infarcted myocardium exhibited a significant increase in damage score compared to non-infarcted myocardium: 6.2 ± 2.0 vs. 4.3 ± 1.5 (mean ± standard deviation), (p = 0.004). In the infarcted myocardium, ultrasound exposure yielded a further significant increase of damage scores: 8.1 ± 1.7 vs. 6.2 ± 2.0 (p = 0.027). CONCLUSION: Our results suggest an instantaneous additive effect on the ischemic damage in myocardial tissue when exposed to ultrasound of stated characteristics. The ultimate damage degree remains to be clarified

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

Self-Treatment Techniques in Patients with Paroxysmal Atrial Fibrillation and the Probable Influence of the Autonomic Nervous System

Self-treatment techniques in patients with paroxysmal atrial fibrillation (PAF) have seldom been described. It has been suggested that PAF attacks might be initiated by changes in the tonus of the autonomic nervous system. Our aim was to study patients’ measures to terminate PAF attacks and to evaluate the possible influence of the autonomic nervous system on start and stop mechanisms

β-blockers after myocardial infarction and 1-year clinical outcome - A retrospective study

Background: Long term β-blocker therapy after myocardial infarction (MI) reduces mortality and recurrent MI but evidence for this treatment predates contemporary acute coronary care. β-blocker treatment is a key quality of care indicator in the Swedish national quality register for acute coronary care, Riks-HIA. Between 2011 and 2015 a declining number of MI-patients discharged with a β-blocker from the coronary care unit (CCU) at Helsingborg and other hospitals was reported. This retrospective observational study aimed to investigate the causes for discharge without a β-blocker and relate it to outcome, compared to patients discharged with a β-blocker. Methods: MI-patients registered in Riks-HIA discharged without β-blocker during 2011-2015 (no-β-group) and a control group (β-group) comprised of patients discharged with β-blocker treatment between January 1 to December 31, 2013, were matched by RIKS-HIA criteria for β-blocker use. Clinical characteristics, date of death, readmission for MI, other cardiovascular events were collected from Riks-HIA and medical records. Results: The no-β-group included 141 patients, where 65.2% had a justified reason for non-β-blocker use. The β-group included 206 patients. There was no difference in cardiovascular risk factor profile. There were a trend towards a higher number of readmissions for MI in the no-β-group was (n = 8 (5.7%) vs n = 2 (1.0%), p = 0.02), but not mortality (6 (4.3%) vs 2 (1.0%), p = 0.07) and combined readmission for angina pectoris, heart failure, arrhythmias or stroke/TIA (n = 23 (16.3%) vs n = 25 (12.1%), p = 0.27). Conclusion: A majority of the patients in the no-β-group had a justified absence of a β-blocker. β-blocker treatment post-MI showed a trend towards fewer readmissions for MI. But important quality information is lacking to make a firm conclusion of the effect on outcome

LONG-TERM ADHERENCE TO FLECAINIDE AS A RHYTHM CONTROL THERAPY IN RECURRENT ATRIAL FIBRILLATION - A RETROSPECTIVE COHORT STUDY

Background: The choice of rhythm control drugs for recurrent atrial fibrillation (AF) remains empirical and is based on the safety profile rather than predicted efficacy. Flecainide is recommended for prevention of AF recurrence in patients without structural heart disease however predictors of treatment success are insufficiently studied. Objective: To assess clinical characteristics associated with flecainide treatment success in patients with recurrent AF. Methods: Using hospital medical records, 135 consecutive adult AF patients who were referred for in-hospital initiation of flecainide were included (median age 62 (IQR 53-70) years, 35% females, 28% persistent AF, median CHA2DS2-VASc score 1, median follow up time 14.5 (IQR 3.3-32.7) months). Patient characteristics at admission, including left atrial enlargement (LAE) assessed as LA volume index >34 ml/m2, were retrieved from medical records. Kaplan Meier curve and Cox regression analysis were used to analyse the association between the clinical characteristics and the likelihood of the drug discontinuation due to failed rhythm control efficacy (primary endpoint) or discontinuation for any reason (secondary endpoint). Results: By the end of follow up 88 patients (65.0%) had continued flecainide therapy. Reasons for discontinuation were failed efficacy (16.0%), side effects (7.0%) or safety issues (16.0 %) such as proarrhythmia (6.7%), heart failure (2.2%), coronary heart disease (1.5%), QRS widening (1.5%), QTc ≥500 ms (0.7%) or AV block II (0.7%). Age ≥60 years, male gender, height and LAE were significant predictors of therapy discontinuation in the univariate analysis, however only LAE (HR=3.9 95% CI 1.1-13.5 for the primary (Figure A) and HR=2.5 95%CI 1.3-4.9 for the secondary endpoints) and age ≥60 years (HR=3.9 95% CI 1.1-11.9 for the primary and HR=2.2 95%CI 1.1-4.3 for the secondary endpoint) remained independent predictors of therapy discontinuation in the multivariate analysis. The outcome did not differ between paroxysmal and persistent AF (Figure B). [Formula presented] [Formula presented] Conclusion: LAE and age ≥60 years were associated with flecainide rhythm control failure in patients with recurrent AF. The vast majority of all treatment failures occured within 6 months from the treatment start. AF type did not significantly predict treatment efficacy