Which task is most appropriate for a registered nurse to delegate to a licensed practical/vocational nurse during an allergic reaction?

Delegating the task of administering skin testing by the cutaneous scratch method to a licensed practical nurse (LPN) or vocational nurse (LVN) is appropriate because this task falls within the scope of practice for LPNs/LVNs and requires a level of skill that they are trained to perform. Skin testing is a specific procedure that involves the application of allergens to the skin, and LPNs are trained to perform basic procedures under the supervision of registered nurses or other higher-level healthcare providers.

In contrast, performing a focused physical assessment requires critical thinking and advanced assessment skills that typically fall within the purview of a registered nurse. Similarly, obtaining the health history can involve complex decision-making and assessment skills that are crucial in understanding the patient's allergic history, making it a task better suited for a registered nurse. Teaching the patient about various diagnostic studies involves in-depth knowledge and the ability to tailor information to the patient’s understanding, which is also more aligned with the RN's responsibilities. Thus, the most suitable task to delegate to an LPN/LVN in this context is the specific administration of skin tests, as it is a procedure that falls within their competencies while ensuring patient safety.