Systems and methods for flushing an assessment catheter

A pulmonary diagnostic system, comprising:

• a pulmonary catheter configured to be introduced transtracheally into a lung passageway of a lung segment in a patient, wherein the pulmonary catheter comprises a distal end and a proximal end with a lumen disposed in-between;
• and
• a flushing unit comprising:
• an intake port connectable to a gas source;
• a pressure regulator distal to the intake port configured to regulate the pressure and flow of a clearing gas from the gas source into the flushing unit;
• a first gas restrictive element;
• a fixed volume gas chamber between the intake port and the first gas restrictive element, wherein the gas chamber is configured to store a volume of the clearing gas and act as a flush capacitor, and wherein the first gas restrictive element is configured to regulate delivery of the clearing gas from the gas chamber;
• and
• a control unit configured to control a state of the first gas restrictive element;
• wherein the flushing unit is configured to deliver the clearing gas to the lumen of the pulmonary catheter and out the distal end into the lung passageway with sufficient force to remove debris from the lumen while the distal end is within the lung passageway of the lung segment in the patient.