[Medical Q&A] How does parenteral nutrition “directly” reach the human body?

Planner: Chinese Medical Association

Reviewer: Yu Jianchun, Chief Physician and Professor of Peking Union Medical College Hospital

Parenteral nutrition is the direct delivery of nutrients into the human body through intravenous infusion, thus providing life support for patients with gastrointestinal failure or severe disorders. This form of nutritional therapy bypasses the digestive system and can "go directly" into the human body.

The infusion routes of parenteral nutrition include peripheral venous route and central venous route. Nutritional support via the peripheral venous route (catheter inserted into the peripheral veins such as the arm and back of the hand) is a relatively simple method with low operation risk, but the peripheral vein cannot tolerate hypertonic solutions (such as glucose solutions with a concentration of more than 10% or protein solutions with a concentration of more than 5%), and the injection site needs to be changed regularly to prevent fluid leakage and phlebitis. It is suitable for short-term or low-concentration nutrient solution infusion. Because the nutritional needs of patients are difficult to meet, patients who need home parenteral nutrition support rarely choose this route. Corresponding to the peripheral venous route is the central venous route, such as the superior vena cava route through the internal jugular vein or subclavian vein, and the percutaneous central venous catheter (the catheter is inserted from the peripheral vein, and its end can reach the central vein, which is the well-known PICC) route. PICC is currently a widely used route with low insertion risk and low infection rate. It can be left in place for a long time and is suitable for patients who receive short-term (several weeks to 3 months) parenteral nutrition. If long-term infusion of parenteral nutrition is required, an infusion port (a device that is completely implanted subcutaneously and connected to the central vein via a catheter) can also be selected. This can reduce the pain of frequent catheterization and allow patients to infuse fluids on their own. It is very suitable for patients who need parenteral nutrition support at home. However, this permanent central venous catheter still has some risks, such as the need for puncture operation, limited service life, surgery required for insertion and removal, and high cost.