Proportional assist versus pressure support ventilation: effects on breathing pattern and respiratory work of patients with chronic obstructive pulmonary disease.

Objective: To investigate the breathing pattern and the inspiratory work of breathing (WOB(I)) in patients with chronic obstructive pulmonary disease (COPD) assisted with proportional assist ventilation (PAV) and conventional pressure support ventilation (PSV).

Design: Prospective controlled study.

Setting: Intensive care unit of a university hospital.