Final answer:
IV fat emulsion is added to PN to provide essential fatty acids, increase calories, and maintain balanced nutrition without significantly raising the solution's osmolarity, which is vital for patients who can't eat normally.
Step-by-step explanation:
The question is asking why an intravenous fat emulsion would be added to parenteral nutrition (PN). The primary reason for adding an IV fat emulsion to PN is to provide essential fatty acids and calories in the form of lipids, which are crucial for patients who cannot obtain adequate nutrition orally or enterally. Fat emulsions help to prevent essential fatty acid deficiencies and contribute to the overall caloric intake without increasing the osmolarity of the PN solution significantly, which can be beneficial for patients with fluid restrictions or those at risk of developing complications from hyperosmolar solutions. Additionally, the inclusion of fat emulsions allows for a more balanced source of energy, as fat is a more concentrated source of calories compared to carbohydrates and proteins.