The improvements in semiconductors and modern circuitry allow new waveforms to be created for treating life-threatening heart fibrillation. A comparison of common waveforms shows that there is no definite optimal waveform. Especially in the case of early defibrillation by novices, the question of dosage should be re-discussed. While a physician may be able to dose the intensity of the therapeutic electric shock, one can't expect that from someone having no medical training. Common AEDs have predefined energy levels, that are delivered to a patient regardless of the patient's size and weight, etc. Current-based defibrillation provides a therapy matched to patient parameters, keeping the myocard stress as low as possible so that the heart has better chances of resuming a normal rhythm.

The work presented here is only a part ofthe development for a new current-controlled defibrillator. In the diploma thesis "'Development and construction of a current-controlled defibrillator for clinical tests" the most important part was the control and safety ofthe defibrillator. To ensure a safe circuit design, a nsk-analysis and a Failure Mode and Effects Analysis (FMEA) were necessary. Another major part was the programming of a microcontroller in embedded C and a programmable logic device in Very High Speed Integrated Circuit Descnption Language (VHDL). The circuit had to be constructed, and the defibrillator was optically decoupled from the laptop for safety reasons. The waveform-data can be transmitted to the microcontrollerfrom the laptop, and the logged data is then transmitted back.

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Absiract-Fihrillation of t he Iwan ix one of t he most comnnm reaxons for suchten death. In caxe offibrillation, t he hi w n getx damaged hy hypoxia m t hin min nies. Only a conccpt t hat hotlüy regards t he cardial and pulmonal prohlem can he xuccexxfiil. A comhination ofAED (Auton\aric-E.\iernal-Defibriüator) and breathing nuichine rednces t he rixks of hypoxia. 11 can furthermore beneßtfrom t he conimon itse ofxenxorx and a synchronised course.

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