Fluid bolus therapy is a medical therapy or a diagnostic method?

We read with interest the recently published article about the physiological changes after fluid bolus therapy (FBT) in Critical Care by Glassford et al. [1]. We are concerned about the concept of FBT in this study. The authors claim that alternative interventions to FBT may include a diagnostic low-volume FBT, classic fluid challenge, low-volume FBT and low dose vasopressor therapy, or cardiac output-guided therapy. So, FBT could be interpreted as a treatment and a diagnostic method for hypovolemia. We thought this interpretation would cause misunderstanding about FBT. FBT is commonly used to assess fluid responsiveness in hemodynamic management, which is also called ‘fluid challenge’ [2]. FBT