What type of osmolar imbalance can occur if TPN infusion runs too fast?

When total parenteral nutrition (TPN) is infused too quickly, it can lead to a hyperosmolar imbalance. TPN solutions are designed to provide nutrients and electrolytes in a concentrated form, and if infused rapidly, the osmotic concentration of the blood can increase significantly. This hyperosmolar state occurs because the high concentrations of solutes (such as glucose and electrolytes) that are part of the TPN solution can overwhelm the body's ability to manage these levels effectively, leading to an excess of solute relative to the fluids in the body.

As a result, the osmolarity of the blood increases, which can cause water to be drawn out of the cells into the extracellular space to balance the osmotic pressure. This movement can potentially lead to cellular dehydration and various complications, such as hyperglycemia, fluid shifts, and even acute kidney injury if not managed promptly. Thus, hyperosmolarity fundamentally arises from the rapid infusion of a concentrated nutritional solution beyond what the body can tolerate or metabolize efficiently.