Final answer:
An adult's airway should be suctioned with a 12-14 French catheter to ensure effective suctioning and minimize mucosal trauma.
Step-by-step explanation:
The appropriate size catheter for suctioning an adult's airway is typically 12-14 French. The size of the suction catheter should be appropriate to the internal diameter of the tracheostomy tube or endotracheal tube being used. It is important to use the correct size to ensure effective suctioning while minimizing the risk of trauma to the airway mucosa. The French scale is a unit of measure used for the outer diameter of catheters, where 1 French is equal to 0.33 mm. In this case, a catheter size of 12-14 French would have an outer diameter between 3.96 mm and 4.62 mm.
This size is appropriate for suctioning an adult's airway as it allows for effective removal of secretions without causing significant trauma to the airway walls.