Evaluation of the Pneupac Ventipac portable ventilator: comparison of performance in a mechanical lung and anaesthetized patients.

The performance of the Pneupac Ventipac portable gas-powered ventilator was evaluated in two stages. The accuracy of delivery of the ventilator was assessed using a mechanical lung model at different combinations of compliance and airway resistance to simulate normal and diseased lungs. The performance of the ventilator was then assessed in 20 anaesthetized patients. The tidal volume delivered by the ventilator in airmix mode (nominal inspiratory oxygen fraction (FIO2) 0.45) was between -20 and +30% of the preset tidal volume with the mechanical lung model adjusted to normal adult values of compliance and airway resistance. The corresponding value with the ventilator set to deliver 100% oxygen was between -22 and -7% of the preset tidal volume. The performance of the ventilator decreased when either compliance was reduced or airway resistance was increased in the mechanical lung model; this effect was greater in airmix mode. Delivered tidal volume was between -19 and +12% of the present tidal volume in the group of anaesthetized patients using the ventilator in airmix mode. The ventilator was reliable and simple to use, and performance was within acceptable limits in the anaesthetized patients. However, we recommend that a means of verifying the adequacy of ventilation should always be used when transporting critically ill or anaesthetized patients with any portable ventilator, particularly when lung compliance or airway resistance may be abnormal.