P-Patient or Problem: Who is the patient? What are the most important characteristics of the patient? What is the primary problem, disease, or co-existing condition?  

I-Intervention: What is the main intervention being considered?

C-Comparison: What is the main comparison intervention?

O-Outcome: What are the anticipated measures, improvements, or effects?

Let’s say an overweight woman in her forties has never travelled by airplane before. She is planning an anniversary holiday with her husband including several long flights. She is concerned about the risk of deep vein thrombosis. She would like to know if compression stockings are effective in preventing this condition or whether a few exercises during the flight would be enough. Using this scenario, how would you build a PICO question?

need reference please