1996 Volume 34 Issue 2 Pages 143-150
Proportional assist ventilation (PAV) is a new mode of assist ventilation in which patients have more freedom in controlling their breathing pattern and frequency as compared to volume-cycled ventilation or pressure support ventilation such as BiPAP. Therefore, PAV is more appropriate for ventilatory assists during exercise or in a situation where patients' ventilatory demands greatly vary. We have developed an open-circuit proportional assist ventilator. The ventilator increased the maximal support pressure and the work rate in proportion to the increase in ventilation during incremental exercise up to 80 Watt. The two-dimensional diagram of the rib cage and abdominal motions (Konno-Mead diagram) resembled that during spontaneous breathing, whereas subjects had to activate abdominal muscles at the end of inspiration during exercise with BiPAP for terminating IPAP, which deformed the diagram. We infer that the criterion for detecting the inspiratory-to-expiratory transition is better in our PAV ventilator than in BiPAP. We conclude that our PAV ventilator provides a better ventilatory support for patients with respiratory insufficiency, especially during exercise or rehabilitation.
