Minimally invasive methods, systems and devices are provided for assessing collateral ventilation in the lungs. In particular, collateral ventilation of a target compartment within a lung of a patient is assessed by advancement of a catheter through the tracheobronchial tree to a feeding airway of the target compartment. The feeding airway is occluded by the catheter and the opening and closing of a one-way valve coupled with the catheter is observed. If the valve ceases opening and closing over time, this may indicate that significant collateral ventilation into the target compartment is absent. If the valve continues to open and close over time, significant collateral ventilation into the compartment may be present. Based on the collateral ventilation assessment, a treatment plan may be generated.