A medical apparatus comprising: a catheter for isolating and deflating a hyperinflated lung compartment, said catheter comprising: a catheter body having a distal end, a proximal end, and at least one lumen extending from the distal end to the proximal end, wherein at least a distal portion of the catheter body is adapted to be advanced through the airways of the lung; an expandable occluding member disposed near the distal end of the catheter body, wherein said occluding member is adapted to be expanded in an airway which feeds the hyperinflated lung compartment such that access to the compartment is provided only through the lumen when the occluding member is expanded; and a one-way flow assembly comprising: a one-way flow element adapted to be disposed within or in-line with the lumen so that flow in a distal-to-proximal direction is allowed and flow in a proximal-to-distal direction is inhibited or prevented; and a flow sensor, a pressure sensor and a valve controller; wherein the flow sensor monitors flow to detect the beginning of an inhalation cycle, the pressure sensor monitors pressure to detect the beginning of an exhalation cycle and the valve controller opens the one-way flow element at the beginning of the exhalation cycle to deflate the hyperinflated lung compartment and closes the one-way flow element at the beginning of the inhalation cycle to prevent reinflation of the hyperinflated lung compartment. a catheter body having a distal end, a proximal end, and at least one lumen extending from the distal end to the proximal end, wherein at least a distal portion of the catheter body is adapted to be advanced through the airways of the lung; an expandable occluding member disposed near the distal end of the catheter body, wherein said occluding member is adapted to be expanded in an airway which feeds the hyperinflated lung compartment such that access to the compartment is provided only through the lumen when the occluding member is expanded; and a one-way flow assembly comprising: a one-way flow element adapted to be disposed within or in-line with the lumen so that flow in a distal-to-proximal direction is allowed and flow in a proximal-to-distal direction is inhibited or prevented; and a flow sensor, a pressure sensor and a valve controller; wherein the flow sensor monitors flow to detect the beginning of an inhalation cycle, the pressure sensor monitors pressure to detect the beginning of an exhalation cycle and the valve controller opens the one-way flow element at the beginning of the exhalation cycle to deflate the hyperinflated lung compartment and closes the one-way flow element at the beginning of the inhalation cycle to prevent reinflation of the hyperinflated lung compartment. a one-way flow element adapted to be disposed within or in-line with the lumen so that flow in a distal-to-proximal direction is allowed and flow in a proximal-to-distal direction is inhibited or prevented; and a flow sensor, a pressure sensor and a valve controller; wherein the flow sensor monitors flow to detect the beginning of an inhalation cycle, the pressure sensor monitors pressure to detect the beginning of an exhalation cycle and the valve controller opens the one-way flow element at the beginning of the exhalation cycle to deflate the hyperinflated lung compartment and closes the one-way flow element at the beginning of the inhalation cycle to prevent reinflation of the hyperinflated lung compartment.