Place the nurse's actions in priority order after accidental decannulation of a mature tracheostomy.

Correct sequence
Call help → oxygenate and assess → same-size tube if trained → smaller tube if needed → confirm ventilation and secure.

Why this is correct
The age and type of the stoma and whether the upper airway is patent change the rescue plan. A mature, clearly identified tract is more suitable for trained replacement than a fresh tract, but resistance still raises concern for a false passage. Oxygenation and expert airway support take priority over repeated blind attempts.

NCLEX decision rule
Read the bedside airway information first. Never force a replacement, and do not assume a tracheostomy patient can be oxygenated only through the neck unless the client is a laryngectomy or the upper airway is known to be nonpatent.