Being "intravascularly dry" is often suspected when:
1. Furosemide monotherapy for diuresis is used, which produces metabolic alkalosis and hypernatremia irrespective of someone's true volume status.
2. Low MSFP shock due to vasoplegia in conditions like sepsis. The issue isn't about volume, but rather the pressure driving venous return.
3. Oliguria in the ICU. Many cases are 1) not AKI 2) not fluid responsive and 3) congestive
4. The patient has intracavitary gradients or dynamic LVOTo. These patients behave "super dry" . Preload helps temporarily, but afterload, beta blockade etc. accomplishes same goal in more durable fashion.
5. Pancreatitis patients. These patients have third spacing, sure, but actually are often more distributive. They require some fluids, but routine use of 100+ml/hr IV fluids in the absence of objective markers of low stroke volume and fluid responsiveness leads to many of the iatrogenic complications of pancreatitis we see!