Methods and devices for passive residual lung volume reduction and functional lung volume expansion

A method for detecting collateral ventilation into a lung compartment in a patient, said method comprising:

• sealing a distal end of a catheter in an airway feeding the lung compartment such that access to the compartment is provided only through a passage of the catheter;
• blocking air from entering the lung compartment through the catheter passage while the patient is inhaling by using a one-way flow element so that flow in a distal-to-proximal direction is allowed and flow in a proximal-to-distal direction is inhibited or prevented;
• measuring air flow or accumulation from the catheter over time using a flow-measurement device connectable to the catheter;
• and
• detecting collateral ventilation based on the measured air flow or accumulation from the catheter over time.