In which situation should a non-tunneled catheter not be inserted?

A non-tunneled catheter should not be inserted in the presence of an existing tracheostomy due to the increased risk of complications associated with the procedure. Tracheostomies involve an artificial airway that can complicate the hemodynamics and overall respiratory status of a patient, which may be further exacerbated by the insertion of a non-tunneled catheter.

In these cases, the potential for airway compromise, the altered anatomy, and the risk of infection can lead to more serious complications. Additionally, patients with a tracheostomy may already have complex medical needs, making the use of a non-tunneled catheter inappropriate in favor of selecting access methods that take into consideration the patient's current situation and ensure safety.

On the other hand, the other provided scenarios may warrant the use of a non-tunneled catheter, as they relate to temporary access for various treatments. Short-term hydration, frequent blood sampling, and the administration of non-irritant solutions are indications where a non-tunneled catheter can still be a viable option due to their short-term nature and lower associated risks in those specific contexts.