If you cannot pass a suction catheter, you have established that the tracheostomy tube is blocked or displaced.

You must now salvage the situation. The tube may be sitting in the trachea and be causing obstruction to gas flow via the upper airway. If there is a cuff present, this should be deflated to improve the chance of oxygenating via the upper airways.

Then reassess to see if your interventions have helped.

Fig 1 is a video demonstrating attempted suction in a blocked tube.