Simultaneous Comparison of Many Triphasic Defibrillation Waveforms

Biphasic defibrillation waveforms are now accepted as being more effective at terminating ventricular fibrillation (VF) than monophasic waveforms. If two phases are better than one, this naturally leads to the hypothesis that additional phases improve efficacy. This study tests the hypothesis by adding one additional phase. We examined the efficacy of 18 different triphasic waveforms simultaneously

In-Vitro Investigation of Very Long Defibrillation Shocks: Design and Testing of a Capacitor-Free Defibrillator

Abstrac

Die Wirksamkeit einer biphasischen ansteigenden Defibrillationsimpulsform zur Terminierung von Kammerflimmern - Eine Vergleichsstudie im porcinen Modell der kardiopulmonalen Reanimation

Zusammenfassung Ziel der Studie: Im Rahmen der kardiopulmonalen Reanimation (CPR) gilt die transthorakale Defibrillation als anerkannte und zugleich lebensrettende Therapie des Kammerflimmerns. Marktübliche Defibrillatoren gewährleisten eine biphasische Schockabgabe zumeist als rechteckige oder exponentiell gekürzte Impulsform. Trotz moderner Defibrillationsverfahren besteht in Anbetracht der ernüchternden Überlebensraten nach Herzkreislaufstillstand weiterhin hoher Forschungsbedarf. Unter den Bedingungen eines außerklinischen Reanimationssettings untersuchten wir erstmalig die Wirksamkeit einer neuartigen, ansteigenden Impulsform, für die uns Hinweise auf höhere Konversionsraten vorliegen und verglichen diese mit einer konventionellen rechteckigen Impulsform. Unser Hauptaugenmerk lag auf der ersten Defibrillation; insbesondere sie zählt zu den entscheidenden prognostischen Determinanten eines Wiederbelebungserfolgs. Methodik: Für die vorliegende Studie wurden insgesamt 57 Schweine in zwei Versuchsgruppen ASCDefib (n=26) und CONVDefib (n=26) randomisiert. Zur Kontrolle von Störeinflüssen wurde eine dritte Gruppe SHAM (n=5) gebildet. In beiden Versuchsgruppen wurde Kammerflimmern (VF) zur Herbeiführung eines Herzkreislaufstillstands (CA) induziert. Nach 5 Minuten unbehandeltem CA starteten wir eine CPR mit transthorakalen Defibrillationen nach 2, 4, 6 und 8 Minuten entsprechend der gültigen ERC-Leitlinien. Gemäß dem gruppenspezifischen Versuchsprotokoll erfolgten durch den Studiendefibrillator entweder drei Schockabgaben mit einer ansteigenden Impulsform, gefolgt von einer vierten mit einer konventionellen Impulsform (ASCDefib) oder drei Schockabgaben mit einer konventionellen Impulsform, gefolgt von einer vierten mit einer ansteigenden Impulsform (CONVDefib). Ergebnisse: Im Hinblick auf die Hauptzielgröße erreichten 5 von 26 Tieren (ASCDefib) und 7 von 26 Tieren (CONVDefib) einen first-shock success, d.h. ROSC nach der ersten Defibrillation. Bezogen auf die Gesamtzahl aller Defibrillationen erreichten 8 von 26 Tieren (ASCDefib) und 10 von 26 Tieren (CONVDefib) anhaltendes ROSC. Kein Tier beider Gruppen erreichte ROSC beim Wechsel der Impulsform nach der vierten Defibrillation. In der Nachbeobachtungsphase zeigte sich eine Tendenz zu häufigeren Refibrillationsereignissen wie auch interventionsbedürftigen Arrhythmien nach Verwendung der ansteigenden Impulsform. Schlussfolgerung: Erstmalig konnten wir unter den Umständen eines außerklinischen Reanimationssettings zeigen, dass Defibrillationen mit ansteigenden Impulsformen denen mit rechteckförmigen Impulsformen hinsichtlich ihrer Wirksamkeit zur Herbeiführung eines perfundierenden Spontankreislaufs nicht überlegen sind. Dieses Ergebnis widerspricht früheren Studien, in denen der Einfluss von Ischämie und Thoraxkompressionen wie in unserem Modell keine Berücksichtigung fand. Patientenindividuelle Ansätze zur Verbesserung der Defibrillations- Erfolgschancen scheinen medizinisch und ökonomisch sinnvoller und könnten vielversprechende Erkenntnisse liefern

Flipping Biological Switches: Solving for Optimal Control: A Dissertation

Switches play an important regulatory role at all levels of biology, from molecular switches triggering signaling cascades to cellular switches regulating cell maturation and apoptosis. Medical therapies are often designed to toggle a system from one state to another, achieving a specified health outcome. For instance, small doses of subpathologic viruses activate the immune system’s production of antibodies. Electrical stimulation revert cardiac arrhythmias back to normal sinus rhythm. In all of these examples, a major challenge is finding the optimal stimulus waveform necessary to cause the switch to flip. This thesis develops, validates, and applies a novel model-independent stochastic algorithm, the Extrema Distortion Algorithm (EDA), towards finding the optimal stimulus. We validate the EDA’s performance for the Hodgkin-Huxley model (an empirically validated ionic model of neuronal excitability), the FitzHugh-Nagumo model (an abstract model applied to a wide range of biological systems that that exhibit an oscillatory state and a quiescent state), and the genetic toggle switch (a model of bistable gene expression). We show that the EDA is able to not only find the optimal solution, but also in some cases excel beyond the traditional analytic approaches. Finally, we have computed novel optimal stimulus waveforms for aborting epileptic seizures using the EDA in cellular and network models of epilepsy. This work represents a first step in developing a new class of adaptive algorithms and devices that flip biological switches, revealing basic mechanistic insights and therapeutic applications for a broad range of disorders

A clinical patient vital signs parameter measurement, processing and predictive algorithm using ECG

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.In the modern clinical and healthcare setting, the electronic collection and analysis of patient related vital signs and parameters are a fundamental part of the relevant treatment plan and positive patient response. Modern analytical techniques combined with readily available computer software today allow for the near real time analysis of digitally acquired measurements. In the clinical context, this can directly relate to patient survival rates and treatment success. The processing of clinical parameters, especially the Electrocardiogram (ECG) in the critical care setting has changed little in recent years and the analytical processes have mostly been managed by highly trained and experienced cardiac specialists. Warning, detection and measurement techniques are focused on the post processing of events relying heavily on averaging and analogue filtering to accurately capture waveform morphologies and deviations. This Ph.D. research investigates an alternative and the possibility to analyse, in the digital domain, bio signals with a focus on the ECG to determine if the feasibility of bit by bit or near real time analysis is indeed possible but more so if the data captured has any significance in the analysis and presentation of the wave patterns in a patient monitoring environment. The research and experiments have shown the potential for the development of logical models that address both the detection and short term predication of possible follow-on events with a focus on Myocardial Ischemic (MI) and Infraction based deviations. The research has shown that real time waveform processing compared to traditional graph based analysis, is both accurate and has the potential to be of benefit to the clinician by detecting deviations and morphologies in a real time domain. This is a significant step forward and has the potential to embed years of clinical experience into the measurement processes of clinical devices, in real terms. Also, providing expert analytical and identification input electronically at the patient bedside. The global human population is testing the healthcare systems and care capabilities with the shortage of clinical and healthcare providers in ever decreasing coverage of treatment that can be provided. The research is a moderate step in further realizing this and aiding the caregiver by providing true and relevant information and data, which assists in the clinical decision process and ultimately improving the required standard of patient care

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 389)

This bibliography lists 234 reports, articles, and other documents recently introduced into the NASA Scientific and Technical Information System. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

Cardiac Arrhythmias

Cardiac arrhythmias are common triggers of emergency admission to cardiology or high-dependency departments. Most cases are easy to diagnose and treat, while others may present a challenge to healthcare professionals. A translational approach to arrhythmias links molecular and cellular scientific research with clinical diagnostics and therapeutic methods, which may include both pharmacological and non-pharmacologic treatments. This book presents a comprehensive overview of specific cardiac arrhythmias and discusses translational approaches to their diagnosis and treatment

Study and development of a novel radio frequency electromedical device for the treatment of peri-implantitis: experimental performance analysis, modelling of the electromagnetic interaction with tissues and in vitro and in vivo evaluation

La peri-implantite (PI) è una grave patologia che interessa tessuti peri-implantari molli e duri. Ad oggi, la prevenzione è l’unico mezzo per contrastarla. Recentemente, è stata sperimentata una terapia basata sulla somministrazione di corrente elettrica a radio frequenza (successo: 81%). Il trattamento è stato simulato numericamente, fornendo le distribuzioni di corrente (EC) e campo elettrico (EF) nei tessuti: l’effetto anti-infiammatorio è attribuibile alla EC, quello di rigenerazione ossea al EF. Sono state considerate le misure di bioimpedenza (BM) per individuare le infiammazioni; numericamente si sono osservati cambiamenti nel modulo di impedenza del 4-20% (secondo diversi parametri), anche più alti sperimentalmente (35% infiammazione, 56% PI). Le BM permettono quindi di identificare il tessuto da trattare. Per la ripetibilità, sono state considerate radici di denti naturali, numericamente e sperimentalmente; l’ordine di grandezza è lo stesso (qualche kΩ), anche se ci sono differenze legate alle condizioni di misura. La variabilità intra-soggetto è il 10% in uno stesso giorno, fino al 26% in giorni diversi; quella inter-soggetto è più alta. La sicurezza elettrica è stata attentamente esaminata e si sono individuate le direttive applicabili (IEC 60601-1, 60601-1-2 and 60601-2-2). Sono stati fatti test in vitro per valutare l’effetto della terapia sulla vitalità cellulare: non c’è un significativo aumento della necrosi (vitalità: 85% test, 94% controlli), l’effetto negativo principale è l’apoptosi. Sono stati numericamente indagati possibili effetti termici: non sono stati individuati riscaldamenti nocivi dei tessuti. Si è progettato un nuovo dispositivo (PeriCare®) per trattare la PI, con parti diagnostica (BM) e terapeutica. Si stanno progettando elettrodi specifici e realizzando il prototipo. Si sta compilando il fascicolo tecnico e pianificando i test di conformità, in vista della certificazione. Il dispositivo medico dovrebbe entrare nel mercato entro l’anno.Peri-implantitis is a severe disease affecting hard and soft peri-implant tissues. At present, prevention is the only means to contrast it. Recently, a therapy based on the administration of radio frequency electric current was experimented (success rate: 81%). The treatment was numerically simulated, providing the electric current (EC) and field (EF) distributions in peri-implant tissues: the anti-inflammatory effect can be associated to EC, the bone regeneration to the EF. Bioimpedance measurements (BM) were investigated to detect inflammation; changes in the measured impedance modulus are equal to 4-20% (depending on different parameters) from numerical results, also more evident experimentally (35% inflammation, 56% peri-implantitis). So, BM could allow to detect the tissue to be treated. To evaluate the repeatability, natural tooth roots were numerically and experimentally measured; the order of magnitude is the same (some kΩ), even if there are differences probably due to the measurement conditions. Intra-subject variability was of 10% in the same day, but up to 26% in different days; inter-subject variability was higher. The electrical safety was accurately taken into account. The applicable directives were individuated (IEC 60601-1, 60601-1-2 and 60601-2-2). In vitro tests were carried out to evaluate the effect of the therapy on cell vitality: there is not a significant increase in necrosis (vitality: 85% tests, 94% controls), the main negative effect is apoptosis. Possible thermal effects were numerically investigated: no dangerous tissue heating was observed. A new device for the peri-implantitis treatment, PeriCare®, was designed, with diagnostic (BM) and therapeutic parts. Proper electrodes are being designed and the prototype is being realized. The technical file is being compiled and the conformity verification tests are being planned towards the certification process. Hopefully, the medical device will be placed into the market within this year