PubMed · 15135203
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Christopher W Dueker. 2004. Diving emergencies.. https://doi.org/10.1016/j.resuscitation.2004.04.004
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OBJECTIVES: To apply the mathematical techniques of optimal control theory (OCT) to a validated model of the human circulation during cardiopulmonary resuscitation (CPR), so as to discover improved waveforms for chest compression and decompression that maximize the coronary perfusion pressure (CPP). METHODS: The human circulatory system is represented by seven difference equations that describe the pressure changes in systemic vascular compartments that are caused by chest compression. The forcing term is the intrathoracic pressure that is generated by the external chest compression, which is taken as the control variable for the system. The optimum waveform of this forcing pressure as a function of time, determined from OCT, is that which maximizes the calculated CPP between the thoracic aorta and the superior vena cava over a period of 13.3 seconds of continuous chest compression. RESULTS: The optimal waveform included both compression and decompression of the chest to the maximum allowable extent. Compression-decompression waveforms were rectangular in shape. The frequency of optimal compression-decompression that was found by OCT was 90 per minute. The optimal duty cycle (compression duration per cycle time) was 40%. The CPP for the optimum control waveform was 36 mm Hg vs. 25 mm Hg for standard CPR. CONCLUSIONS: Optimal control theory suggests that both compression and decompression of the chest are needed for best hemodynamics during CPR.
BACKGROUND: Scientific evidence is scarce in relation to the effectiveness of different methods of teaching automated external defibrillator (AED) use to laypeople. A reference course is needed in order to test new courses or methods against a comparative standard. OBJECTIVE: To propose a reference AED provider course that can be used as a comparator when testing new courses or teaching methods. METHODS: All national resuscitation councils that are represented in the European Resuscitation Council were sent a questionnaire about the AED provider courses run by them or under their auspices. RESULTS: Sixteen national resuscitation councils responded to the enquiry. Apart from the individual course timetables, there was remarkable consistency amongst the European countries as regards organisation, structure, content and methods. CONCLUSIONS: A reference AED provider course for laypeople, based on a synthesis of existing European courses, is suggested as a tool for research. Prior completion of a basic life support provider course is mandatory. Course duration is 2 h 45 min (excluding breaks), with 1 h 40 min practice time for the participants, 25 min for theory, 20 min for practical demonstrations by the instructor and 20 min for introduction, discussion and closure. A manual is distributed at the start of the course. The ratio of instructors to participants is one to six. Lectures are interactive between the instructor and the class. AED use is practised in groups of six participants. Participants prove their competency by means of a formal test that simulates a cardiac arrest scenario. Using this course as a comparator during research into the methodology of AED teaching would provide a reference against which other courses could be tested.
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