Chest compressions in cardiopulmonary resuscitation are of utmost importance although not without a risk. Many injuries are described but the incidence of these is hard to define due to methodological differences. It is strenuous to perform chest compressions and therefore mechanical chest compressions have been looked upon with interest. This thesis presents new insights on the panorama and incidence of injuries in modern CPR and a comparison of safety and efficacy between manual chest compressions and mechanical chest compressions with the LUCAS™ device. We also evaluated if computed tomography could be an aid in the detection of these injuries. Two pilot trials were conducted and one presented no difference in early survival with 26% and 31% having return of spontaneous circulation when comparing manual chest compressions with the LUCAS device in out-of-hospital cardiac arrest. The other revealed no difference in autopsy-detected injuries. A third multicentre autopsy trial revealed that in patients treated with manual chest compressions 78.3% had at least one injury and 63.9% had at least one rib fracture. The corresponding numbers for patients treated with the LUCAS device was 92.8% (p = 0.002) and 77.7% (p=0.022). Sternal fractures occurred in 54.2% and in 58.3% of the cases treated with manual chest compressions and the LUCAS device respectively (p = 0.556). The median number of rib fractures was 7 in the group receiving manual chest compressions and 6 in the group receiving chest compressions with the LUCAS device. In 31 cases a computed tomography was conducted prior to autopsy and we found a very strong correlation in the discrimination of patients with or without rib fractures (kappa=0.83). Mean difference between the two methods in detecting rib fractures was 0.16. The detection of other injuries did not have a strong correlation. In conclusion there is no difference in early survival between the two methods and mechanical chest compressions adds 14-15% more patients with rib fractures but the amount of rib fractures, sternal fractures and other injuries is equal. CT can aid but not replace autopsies in the detection of these injuries.

The standard first aid for a heart attack resulting in cardiopulmonary arrest is effective cardiopulmonary resuscitation (CPR). Chest compressions are most commonly performed on a flat surface with the rescuer kneeling next to the victim with one hand on top of the other on the sternum and elbows straight. This technique of being on the ground may be challenging for those without the mobility and strength to get up and down from the ground. In 2005, the American Heart Association (AHA) Guidelines listed “pedal”, or heel, compression as an acceptable alternative to standard chest compressions (Trenkamp & Perez, 2015). That same year, the recommended depth of a compression increased from 3.8 cm to 5.0 cm (Trenkamp & Perez, 2015). To attain such a depth, extra force and strength arerequired. The heel method may be especially reasonable for those rescuers who cannot attain the floor and those who do not have the cardiovascular or muscular strength to perform traditional chest compressions. The purpose of this study was to evaluate the effects of performance of hands only (HO) versus the combination (CO) of hands only plus pedal CPR on the electrocardiogram, including heart rate and heart rhythm. The subjects utilized in this investigation were six men and nine women between 56 and 71 years of age from San Luis Obispo County in California. Subjects underwent two trials with at least a 15 hour rest period in between but no more than one week. Subjects were randomly assigned to either the Combination (CO) trial or the Hands Only (HO) trial. When they came back for their second trial, they did the trial that they did not do the first time. On average, participants were able to sustain the combination of HO plus pedal CPR longer (9.47 minutes) than they were able to perform standard HO CPR (9.02 minutes) but this difference was not statistically significant (p=0.16). Mean maximum heart rate was 133 ± 23.7 bpm during the CO trial and 125.4 ± 21.9 bpm during the HO trial (p=0.12). Mean percentage of the HR reserve was 75.1% during the CO trial and 61.1% during the HO trial (p=0.09). Mean RPE was not significantly different between CO and HO trials (p=0.2124), nor between genders (p=0.42090). However, for both trials combined the mean RPE was significantly greater at 5 minutes of CPR (4.45 ± 0.53) than at 2 minutes of CPR (3.38 ± 0.31), (p It may take time for individuals to accept pedal CPR as a viable resuscitation method. With the majority of sudden cardiac arrests occurring in the home among older adults in society, it is important to recognize that pedal CPR is an acceptable method and that a rescuer may have this choice if they either need a break from standard CPR or if they can not attain the ground.

Nationellt drabbas varje år flera tusentals människor av hjärtstopp utanför sjukhus. För att öka chansen till överlevnad hos dessa individer är snabbt påbörjad hjärt-lungräddning av god kvalité av största vikt. Då det är fysiskt ansträngande att utföra hjärt-lungräddning, samt under vissa omständigheter svårt att utföra med bibehållen effektivitet och kvalité, har apparater som kan ge mekaniska bröstkompressioner utvecklats. Syfte: Syftet med studien var att undersöka vilka resultat mekaniska bröstkompressioner har vid hjärtstopp utanför sjukhus. Metod: Studien genomfördes som en allmän litteraturöversikt med en induktiv ansats. Efter kvalitetsgranskning inkluderades totalt 16 vetenskapliga artiklar där majoriteten var kvantitativa studier. Artiklarna inhämtades från databaserna PubMed och CINAHL. Databearbetning genomfördes utifrån en integrerad analys där teman identifierades. Resultat: Den integrerade analysen resulterade i fyra teman; överlevnad, återkomst av spontan cirkulation [ROSC], neurologisk funktion och övriga resultat. Ingen skillnad kunde ses i överlevnad och neurologisk funktion mellan mekaniska bröstkompressioner och manuella bröstkompressioner. Snarare ses en tendens till sämre överlevnad och sämre neurologisk funktion vid användning av mekaniska bröstkompressioner. I övrigt noteras förlängd tid till första defibrillering vid användning av mekaniska bröstkompressioner. Slutsats: De granskade studierna visade att användandet av mekaniska bröstkompressioner vid hjärtstopp utanför sjukhus inte har någon uppenbar fördel gällande överlevnad och neurologisk funktion jämfört med manuella bröstkompressioner. / Nationally, several thousands of people suffer from out-of-hospital cardiac arrest each year. In order to increase the chance of survival in these individuals, cardiac resuscitation of good quality is of the utmost importance. Since it is physically strenuous to perform cardiac resuscitation, and in some circumstances difficult to perform with maintained efficiency and quality, devices that can provide mechanical chest compressions have been developed. Aim: The aim of the study was to investigate the results of mechanical chest compressions on out-of-hospital cardiac arrest. Method: The study was conducted as a general literature review with an inductive approach. After quality review, a total of 16 scientific articles were included, the majority of which were quantitative studies. The articles were obtained from the PubMed and CINAHL databases. Data processing was performed on the basis of an integrated analysis where themes were identified. Results: The integrated analysis resulted in four themes; survival, return of spontaneous circulation [ROSC], neurological function and other results. No difference was seen in survival and neurological function between mechanical chest compressions and manual chest compressions. Rather, there is a tendency towards poorer survival and poorer neurological function when using mechanical chest compressions. Otherwise, extended time to first defibrillation is noted when using mechanical chest compressions. Conclusion: The studies reviewed showed that the use of mechanical chest compressions in out-of-hospital cardiac arrest has no apparent benefit on survival and neurological function compared to manual chest compressions.

Factors affecting the risk of ribcage injury in adult subjects during CPR were investigated using the torso region of the THUMS model, a full human body FE-model, representing an average adult male. The thoracic dynamic response of the model was compared to experimental PMHS hub loading impact data and live-subject CPR data found in the literature. The model was then used to study the risk of obtaining injuries in various simulated CPR conditions, also varying the stiffness of the costal cartilage. Parameters that are known to predict induced injuries were extracted from the model simulations, i.e. chest deflections, and maximum 1st principal strain and von-Mises stress in the ribs and sternum, as well as the pressure in the heart muscle. These were compared with values that have been reported to have the potential to cause injury. The predictions were compared to experimental findings of the probability of CPR resulting in fractures of the ribs and sternum. The previously mentioned parameters did not reach high enough values to predict fracture occurrences, but interesting trends were highlighted with regards to the different loading conditions investigated. It was demonstrated that human body FE-model simulation studies can be useful for investigating the influence of different CPR related loading conditions on the risk of occurrences of rib and sternal fractures.

L'arrêt cardiaque est principalement d'étiologie cardio-vasculaire. Dans le contexte actuel des arrêts cardiaques extrahospitaliers, 20 à 25% des victimes présentent une fibrillation ventriculaire. Environ 3 à 5% des personnes sont sauvées sans séquelle neurologique. La survie à un arrêt cardiaque extrahospitalier dépend d'une prise en charge précoce et rapide de la victime. Les premiers témoins actifs réalisant la réanimation cardio-pulmonaire combinée à l'utilisation d'un défibrillateur sont ainsi un maillon important pour sauver la victime.Notre objectif principal est d'améliorer le taux de survie à un arrêt cardiaque extrahospitalier. Une première voie d'investigation est de proposer un fonctionnement de défibrillateur optimal combinant judicieusement les différents modules de détection embarqués (détection de fibrillation ventriculaire, détection de massage cardiaque, détection d'interférences électromagnétiques) afin de réduire les temps de pause péri-choc durant la procédure de réanimation. En effet, pendant ces temps, dits « hands-off » en anglais, aucun geste de secours n'est administré au patient qui, lui, voit d'une part sa pression de perfusion coronarienne chuter, d'autre part la probabilité de succès des tentatives de défibrillation décroître. C'est pourquoi une deuxième voie d'investigation porte sur la prédiction de l'efficacité de choc. Dans ce contexte, nous proposons de combiner des paramètres de l'électrocardiogramme dans les domaines temporel, fréquentiel et de la dynamique non-linéaire. Un classifieur bayésien utilisant le modèle de mélange de gaussiennes a été appliqué aux vecteurs de paramètres les plus prédicteurs de l'issue de la défibrillation et l'algorithme Espérance-Maximisation a permis de mener à bien la procédure d'apprentissage des paramètres du modèle probabiliste représentant les distributions conditionnelles de classe.L'ensemble des méthodes proposées a permis d'atteindre des résultats prometteurs pour à la fois réduire les temps de pause péri-choc et prédire l'efficacité de défibrillation et ainsi espérer améliorer le taux de survie à un arrêt cardiaque / The cardiac arrest is mainly of cardiovascular etiology. In the actual context of out-of-hospital cardiac arrests, 20 to 25% of the victims present a ventricular fibrillation. About 3 to 5% of the victims are saved without neurological damage. The chance of surviving a cardiac arrest outside an hospital depends on the early and fast support of the victim. The first active witnesses performing cardiopulmonary resuscitation combined with the use of a defibrillator are an important link to save the victim.Our main objective is to improve survival rate in out-of-hospital cardiac arrest cases. A first way of investigation is to propose an optimal functioning of defibrillator combining wisely the different processes of detection embedded (ventricular fibrillation detection, chest compressions detection, electromagnetic interferences detection), in order to reduce the peri-shock pauses during the resuscitation procedure. In fact, during these pauses, known as "hands-off" pauses, no emergency action is provided to the patient, what is correlated to a drop of the coronary pression, but also to a decrease of the chance of successful defibrillation. That is the reason why, a second way of investigation is based on the prediction of the efficiency of defibrillation. In this context, we propose to use a combination of parameters extracted from electrocardiogram in time, frequency and non-linear dynamics domains. A bayesian classifier using a gaussian mixture model was applied to the vectors of parameters, which are the most predictor of the defibrillation outcome and the algorithm Expectation-Maximization allowed to learn the parameters of the probabilistic model representing the class conditional distributions.All of the proposed methods allowed to reach promising results for both reducing the peri-shock pauses and predicting the efficiency of defibrillation in hope to improve the survival rate in cardiac arrest cases