Parenteral Nutrition (PN) is a method of delivering essential nutrients directly into the bloodstream via intravenous infusion, primarily used for patients who cannot take sufficient nutrition orally or through the gastrointestinal tract. This therapy provides comprehensive nutritional support, including carbohydrates, proteins, fats, electrolytes, and vitamins, ensuring the patient maintains basic metabolic needs and tissue repair during illness or post-surgery.
The core of this treatment is to mimic intestinal absorption pathways by directly delivering nutrients into the blood, suitable for patients with severe gastrointestinal dysfunction or prolonged fasting. Physicians tailor individualized formulas based on the patient’s age, weight, and severity of illness to prevent malnutrition or metabolic disturbances.
Parenteral nutrition mainly divides into two categories: “Total Parenteral Nutrition” and “Partial Supplementation.” “Total Parenteral Nutrition” contains all essential nutrients and is suitable for patients unable to eat at all; “Partial Supplementation” targets specific nutrient deficiencies. The mechanism involves infusing nutrient solutions through a central venous catheter, which are directly utilized by cells to support tissue repair and immune function.
The formula composition includes glucose for energy, amino acids for protein synthesis, lipid emulsions providing essential fatty acids, and electrolytes to maintain fluid balance. Vitamins and minerals ensure normal metabolic pathways. The treatment requires strict monitoring of blood glucose, liver function, and blood lipids to avoid metabolic imbalances.
Primarily used for patients with gastrointestinal loss or severe impairment, such as short bowel syndrome, severe burns, or post-chemotherapy malabsorption. It is also commonly used during postoperative recovery or in patients with long-term coma to maintain nutritional status. Additionally, congenital metabolic disorders or severe malabsorption syndromes are important indications.
When patients have a reduced oral intake below 60% of their needs for more than a week due to disease or treatment, they meet the criteria for initiating parenteral nutrition. For example, during the acute phase of pancreatitis or severe Crohn’s disease flare-ups, the gastrointestinal tract cannot handle normal digestion and relies entirely on intravenous nutrition.
The therapy is usually administered via a central venous catheter (such as Hickman line or PICC), with daily doses calculated based on the patient’s weight. Adult baseline formulas typically include 3-4g/kg of amino acids, with 60-70% of calories from glucose, and lipid emulsions accounting for 30% of calories. Doses are adjusted for children and special patients.
Infusion rates should be slow and steady. Total parenteral nutrition generally lasts from several weeks to months, while partial supplementation may only be needed short-term. Physicians adjust formulas weekly based on blood glucose, blood lipids, and liver function monitoring results.
For patients with severe burns or post-major surgery, it can significantly shorten recovery time. Compared to enteral nutrition, it completely bypasses the gastrointestinal burden, especially suitable for cases of complete bowel obstruction or loss of function.
Serious risks include:
Common side effects include phlebitis, lipid metabolism abnormalities, or micronutrient toxicity. Long-term use may lead to cholestasis or osteoporosis, requiring regular monitoring of liver function and bone density.
Contraindications include severe liver failure, uncontrolled hyperglycemia or hyperlipidemia, and uncontrolled catheter infection. Patients with coagulopathy should use cautiously due to increased risk of thrombosis. Pregnant women or those with severe renal impairment require formula adjustments.
During treatment, daily monitoring of vital signs and blood glucose is necessary, with weekly blood tests for liver function, electrolytes, and renal function. If fever, redness or swelling at the puncture site, or altered consciousness occurs, treatment should be stopped immediately and infection evaluated.
When used with chemotherapy drugs, nutrient formulas should be adjusted to avoid impaired drug metabolism. Antibiotics should be compatible with the nutritional components; for example, aminoglycosides may enhance hepatotoxicity. Diuretics require electrolyte adjustments.
When used with immunosuppressants, liver function should be monitored as some drugs may interfere with vitamin metabolism. Patients undergoing radiotherapy should supplement with antioxidants to reduce tissue damage.
Clinical studies show that parenteral nutrition can increase survival rates in short bowel syndrome patients by 40-60%. Patients undergoing major abdominal surgery using this therapy have an average hospital stay reduced by 5-7 days. Long-term nutritional solutions can reduce infection complications to below 12%.
In pediatric patients, growth and developmental indices can recover to over 85% of normal curves. Multicenter studies confirm that standardized formulas can keep fatty liver incidence below 15%, with precise monitoring and formula adjustments being key to success.
Enteral nutrition (EN) is the primary alternative, delivered via nasogastric or gastrostomy tubes. Oral nutritional supplements are suitable for mildly malnourished patients. In special cases, combined enteral and parenteral therapy may be used, such as in patients with partial gut recovery.
Short-term nutritional support can consider enteral nutrition combined with oral intake. However, in cases of complete bowel obstruction or during chemotherapy, parenteral nutrition remains the only option. Treatment strategies are determined based on gut recovery potential and disease severity.
Patients should strictly follow hygiene instructions from the medical team, including thorough handwashing or use of disinfectant gel before touching the catheter. Daily inspection of the puncture site for redness, swelling, discharge, or fever is necessary, and dressings should be kept dry and clean. When changing dressings or handling the catheter, sterile techniques must be used. If infection symptoms appear, notify healthcare providers immediately.
How to manage abnormal blood glucose levels during parenteral nutrition?Regular monitoring of blood glucose is essential, especially for diabetic or metabolic disorder patients. Nutritionists will adjust glucose concentration and insulin dosage based on blood glucose data. Patients should avoid self-adjusting infusion rates or formulas and report symptoms like dizziness or frequent urination promptly.
What should long-term parenteral nutrition patients pay attention to regarding bone health?Prolonged therapy may lead to osteoporosis; regular bone density scans are recommended. Doctors may prescribe calcium and vitamin D supplements and suggest weight-bearing exercises. If there is a history of fractures or signs of bone loss, the nutritional formula will be adjusted to strengthen bone health.
How to handle liver function abnormalities during parenteral nutrition?Regular blood tests for liver enzymes such as ALT, ALP, or bilirubin are necessary. If abnormal levels are detected, the physician may suspend therapy or adjust lipid emulsions and vitamin doses. Avoiding concurrent hepatotoxic medications and following a low-fat diet can help reduce liver burden.
How to maintain catheter patency during parenteral nutrition?Daily flushing with saline as per medical instructions is necessary to prevent blood clotting and catheter occlusion. If resistance to infusion increases or fluid retention occurs, check catheter position and contact healthcare providers for professional handling. Avoid forceful flushing or pulling on the catheter to prevent vascular injury.
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