Abstract: A device for measuring a gas flow, has a measurement chamber and an ultrasonic transceiver unit which can be attached to the measurement (chamber over openings of the measurement chamber and which is provided with transmit and receive heads. The heads are directed against the openings of the measurement chamber, membranes being arranged between the measurement chamber and the transmit and receive heads which are permeable to ultrasound waves but largely impermeable to moisture and bacteria. In order to feed maximum acoustical energy to the ultrasonic transceiver unit while keeping moisture and bacteria away from the unit, the membranes are replaceably arranged close to the transmit and receive heads.

Abstract: A method and device for monitoring the condition of at least one filter arranged in a flow path of a ventilator. Flow measurement signals are obtained from a first flow meter and a second flow meter and pressure signals are obtained from a first pressure meter and a second pressure meter. When a filter in the inspiratory section of the ventilator is to be tested, flow through the filter and the drop in pressure across the filter are determined from the pressure measured by the first pressure meter and the second pressure meter. If the drop in pressure in relation to the flow lies within predefined limits, the filter is deemed to be serviceable. In a corresponding manner, another filter in the expiratory line can be tested, wherein flow through the filter is determined by the second flow meter.

Abstract: An implantable defibrillator has a capacitor which, through a controllable switch arrangement, can either be connected to a voltage source for charging the capacitor, or connected across electrodes placed at the heart for delivering a defibrillation pulse. To calculate the minimum pulse energy required for successful defibrillation, ventricular fibrillation is first induced, so that a plurality of defibrillation attempts, with energy increasing from attempt-to-attempt can be undertaken until successful defibrillation occurs. For inducing ventricular fibrillation, the capacitor of the implantable defibrillator is connected to the voltage source until a prescribed charging voltage, which is significantly below the voltage necessary for defibrillation, is reached, and subsequently, the capacitor is disconnected from the voltage source during brief time spans at intervals within the framework of a sequence and is connected during those time spans to the electrodes.