Inspiratory effort and breathing pattern change in response to varying the assist level: A physiological study.

Aim: To describe the response of breathing pattern and inspiratory effort upon changes in assist level and to assesss if changes in respiratory rate may indicate changes in respiratory muscle effort.

Methods: Prospective study of 82 patients ventilated on proportional assist ventilation (PAV+). At three levels of assist (20 %-50 %-80 %), patients' inspiratory effort and breathing pattern were evaluated using a validated prototype monitor.