A new ventilator converter with the Siemens Servo Ventilator--evaluation in a lung model

A ventilator converter device (Anmedic) for connecting a non-rebreathing ventilator (Servo Ventilator 900 B; Siemens-Elema) to a circle anaesthesia system was evaluated in a lung model. Recorded minute ventilation was slightly lower than dialled in most cases. We furthermore found inadequate expiratory expansion of the ventilator converter bellows, with progressive loss of tidal volume and consequently recorded minute volume, when fresh gas flow to the circle system was low (1 l.min-1), expiratory time was short (less than 40%) and respiratory obstruction was present.