Basic concept
Parenteral nutrition (PN) is the supply of nutrition from intravenous as the nutritional support before and after surgery and for critically ill patients. All nutrition is supplied parenterally, called total parenteral nutrition (TPN). The routes of parenteral nutrition include peripheral intravenous nutrition and central intravenous nutrition. Parenteral nutrition (PN) is the intravenous supply of nutrients needed by patients, including calories (carbohydrates, fat emulsions), essential and non-essential amino acids, vitamins, electrolytes, and trace elements. Parenteral nutrition is divided into complete parenteral nutrition and partial supplemental parenteral nutrition. The purpose is to enable patients to maintain nutritional status, weight gain and wound healing even when they cannot eat normally, and young children can continue to grow and develop. Intravenous infusion routes and infusion techniques are necessary guarantees for parenteral nutrition.
Indications
The basic indications for parenteral nutrition are those with gastrointestinal dysfunction or failure, including those who need home parenteral nutrition support.
Significant effect
1. Gastrointestinal obstruction
2. Absorption dysfunction of gastrointestinal tract: ① Short bowel syndrome: extensive small bowel resection >70%~80%; ② Small bowel disease: immune system disease, intestinal ischemia, multiple intestinal fistulas; ③ Radiation enteritis, ④ Severe diarrhea, intractable Sexual vomiting > 7 days.
3. Severe pancreatitis: First infusion to rescue shock or MODS, after the vital signs are stable, if intestinal paralysis is not eliminated and enteral nutrition cannot be fully tolerated, it is an indication for parenteral nutrition.
4. High catabolic state: extensive burns, severe compound injuries, infections, etc.
5. Severe malnutrition: Protein-calorie deficiency malnutrition is often accompanied by gastrointestinal dysfunction and cannot tolerate enteral nutrition.
Support is valid
1. Perioperative period of major surgery and trauma: Nutritional support has no significant effect on patients with good nutritional status. On the contrary, it may increase infection complications, but it can reduce postoperative complications for patients with severe malnutrition. Severely malnourished patients need nutritional support for 7-10 days before surgery; for those who are expected to fail to recover gastrointestinal function within 5-7 days after major surgery, parenteral nutritional support should be started within 48 hours after surgery until the patient can have adequate nutrition. Enteral nutrition or food intake.
2. Enterocutaneous fistulas: Under the condition of infection control and adequate and proper drainage, nutritional support can make more than half of enterocutaneous fistulas heal themselves, and definitive surgery has become the last treatment. Parenteral nutrition support can reduce gastrointestinal fluid secretion and fistula flow, which is beneficial to control infection, improve nutritional status, improve cure rate, and reduce surgical complications and mortality.
3. Inflammatory bowel diseases: Crohn’s disease, ulcerative colitis, intestinal tuberculosis and other patients are in active disease stage, or complicated with abdominal abscess, intestinal fistula, intestinal obstruction and bleeding, etc., parenteral nutrition is an important treatment method. It can relieve symptoms, improve nutrition, rest the intestinal tract, and facilitate the repair of intestinal mucosa.
4. Severely malnourished tumor patients: For patients with body weight loss ≥ 10% (normal body weight), parenteral or enteral nutrition support should be provided 7 to 10 days before surgery, until enteral nutrition or return to eating after surgery. until.
5. Insufficiency of important organs:
① Liver insufficiency: patients with liver cirrhosis are in a negative nutritional balance due to insufficient food intake. During the perioperative period of liver cirrhosis or liver tumor, hepatic encephalopathy, and 1 to 2 weeks after liver transplantation, those who cannot eat or receive enteral nutrition should be given parenteral nutrition Nutritional support.
② Renal insufficiency: acute catabolic disease (infection, trauma or multiple organ failure) combined with acute renal failure, chronic renal failure dialysis patients with malnutrition, and need parenteral nutrition support because they cannot eat or receive enteral nutrition. During dialysis for chronic renal failure, parenteral nutrition mixture can be infused during intravenous blood transfusion.
③ Heart and lung insufficiency: often combined with protein-energy mixed malnutrition. Enteral nutrition improves clinical status and gastrointestinal function in chronic obstructive pulmonary disease (COPD) and may benefit patients with heart failure (evidence is lacking). The ideal ratio of glucose to fat in COPD patients has not yet been determined, but the fat ratio should be increased, the total amount of glucose and infusion rate should be controlled, protein or amino acids should be provided (at least lg/kg.d), and sufficient glutamine should be used for patients with critical lung disease. It is beneficial to protect alveolar endothelium and intestinal-associated lymphoid tissue and reduce pulmonary complications. ④Inflammatory adhesive intestinal obstruction: perioperative parenteral nutrition support for 4 to 6 weeks is beneficial to the recovery of intestinal function and the relief of obstruction.
Contraindications
1. Those with normal gastrointestinal function, adapting to enteral nutrition or recovering gastrointestinal function within 5 days.
2. Incurable, no hope of survival, dying or irreversible coma patients.
3. Those who need emergency surgery and cannot implement nutritional support before surgery.
4. Cardiovascular function or severe metabolic disorders need to be controlled.
Nutritional pathway
Selection of the appropriate route of parenteral nutrition depends on factors such as the patient’s vascular puncture history, venous anatomy, coagulation status, expected duration of parenteral nutrition, the setting of care (hospitalized or not), and the nature of the underlying disease. For inpatients, short-term peripheral venous or central venous intubation is the most common choice; for long-term treatment patients in non-hospital settings, peripheral venous or central venous intubation, or subcutaneous infusion boxes are most commonly used.
1. Peripheral intravenous parenteral nutrition route
Indications: ① Short-term parenteral nutrition (<2 weeks), nutrient solution osmotic pressure less than 1200mOsm/LH2O; ② Central venous catheter contraindication or infeasible; ③ Catheter infection or sepsis.
Advantages and disadvantages: This method is simple and easy to implement, can avoid complications (mechanical, infection) related to central venous catheterization, and is easy to detect the occurrence of phlebitis early. The disadvantage is that the osmotic pressure of the infusion should not be too high, and repeated puncture is required, which is prone to phlebitis. Therefore, it is not suitable for long-term use.
2. Parenteral nutrition via central vein
(1) Indications: parenteral nutrition for more than 2 weeks and nutrient solution osmotic pressure higher than 1200mOsm/LH2O.
(2) Catheterization route: through the internal jugular vein, the subclavian vein or the peripheral vein of the upper extremity to the superior vena cava.
Advantages and disadvantages: The subclavian vein catheter is easy to move and care, and the main complication is pneumothorax. Catheterization through the internal jugular vein limited the jugular movement and dressing, and resulted in slightly more complications of local hematoma, arterial injury and catheter infection. Peripheral vein-to-central catheterization (PICC): The precious vein is wider and easier to insert than the cephalic vein, which can avoid serious complications such as pneumothorax, but it increases the incidence of thrombophlebitis and intubation dislocation and the difficulty of operation. The unsuitable parenteral nutrition routes are the external jugular vein and the femoral vein. The former has a high rate of misplacement, while the latter has a high rate of infectious complications.
3. Infusion with subcutaneously embedded catheter through central venous catheter.
Nutrition system
1. Parenteral nutrition of different systems (multi-bottle serial, all-in-one and diaphragm bags):
①Multi-bottle serial transmission: Multiple bottles of nutrient solution can be mixed and serially transmitted through the “three-way” or Y-shaped infusion tube. Although it is simple and easy to implement, it has many disadvantages and should not be advocated.
②Total nutrient solution (TNA) or all-in-one (AIl-in-One): The aseptic mixing technology of total nutrient solution is to combine all parenteral nutrition daily ingredients (glucose, fat emulsion, amino acids, electrolytes, vitamins and trace elements) ) mixed in a bag and then infused. This method makes the input of parenteral nutrition more convenient, and the simultaneous input of various nutrients is more reasonable for anabolism. Finishing Because the fat-soluble plasticizer of polyvinyl chloride (PVC) bags can cause certain toxic reactions, polyvinyl acetate (EVA) has been used as the main raw material of parenteral nutrition bags at present. In order to ensure the stability of each component in the TNA solution, the preparation should be carried out in the specified order (see Chapter 5 for details).
③Diaphragm bag: In recent years, new technologies and new material plastics (polyethylene/polypropylene polymer) have been used in the production of finished parenteral nutrition solution bags. The new full nutrient solution product (two-chamber bag, three-chamber bag) can be stored at room temperature for 24 months, avoiding the pollution problem of nutrient solution prepared in the hospital. It can be more safely and conveniently used for parenteral nutrition infusion through central vein or peripheral vein in patients with different nutritional needs. The disadvantage is that the individualization of the formula cannot be achieved.
2. Composition of parenteral nutrition solution
According to the patient’s nutritional needs and metabolic capacity, formulate the composition of nutritional preparations.
3. Special matrix for parenteral nutrition
Modern clinical nutrition uses new measures to further improve nutritional formulations to improve patient tolerance. In order to meet the needs of nutritional therapy, special nutritional substrates are provided for special patients to improve the patient’s immune function, improve the intestinal barrier function, and improve the body’s antioxidant capacity. The new special nutritional preparations are:
①Fat emulsion: including structured fat emulsion, long-chain, medium-chain fat emulsion, and fat emulsion rich in omega-3 fatty acids, etc.
②Amino acid preparations: including arginine, glutamine dipeptide and taurine.
Table 4-2-1 Energy and protein requirements of surgical patients
Patient condition energy Kcal/(kg.d) protein g/(kg.d) NPC: N
Normal-moderate malnutrition 20~250.6~1.0150:1
Moderate stress 25~301.0~1.5120:1
High metabolic stress 30~35 1.5~2.0 90~120:1
Burn 35~40 2.0~2.5 90~120: 1
NPC: N non-protein calorie to nitrogen ratio
Parenteral nutrition support for chronic liver disease and liver transplantation
Non-protein energy Kcal/(kg.d) protein or amino acid g/(kg.d)
Compensated cirrhosis25~35 0.6~1.2
Decompensated cirrhosis 25~35 1.0
Hepatic encephalopathy 25~35 0.5~1.0 (increase the ratio of branched-chain amino acids)
25~351.0~1.5 after liver transplantation
Matters needing attention: Oral or enteral nutrition is usually preferred; if it is not tolerated, parenteral nutrition is used: energy is composed of glucose [2g/(kg.d)] and medium-long-chain fat emulsion [1g/(kg.d) ], fat accounts for 35~50% of calories; nitrogen source is provided by compound amino acids, and hepatic encephalopathy increases the proportion of branched-chain amino acids.
Parenteral nutrition support for acute catabolic disease complicated with acute renal failure
Non-protein energy Kcal/(kg.d) protein or amino acid g/(kg.d)
20~300.8~1.21.2~1.5 (daily dialysis patients)
Matters needing attention: Oral or enteral nutrition is usually preferred; if it is not tolerated, parenteral nutrition is used: the energy is composed of glucose [3~5g/(kg.d)] and fat emulsion [0.8~1.0g/(kg.d) )]; non-essential amino acids (tyrosine, arginine, cysteine, serine) of healthy people become conditionally essential amino acids at this time. Blood sugar and triglycerides should be monitored.
Table 4-2-4 Recommended daily amount of total parenteral nutrition
Energy 20~30Kcal/(kg.d) [Water supply 1~1.5ml per 1Kcal/(kg.d)]
Glucose 2~4g/(kg.d) Fat 1~1.5g/(kg.d)
Nitrogen content 0.1~0.25g/(kg.d) Amino acid 0.6~1.5g/(kg.d)
Electrolytes (average daily requirement for parenteral nutrition adults) Sodium 80~100mmol Potassium 60~150mmol Chlorine 80~100mmol Calcium 5~10mmol Magnesium 8~12mmol Phosphorus 10~30mmol
Fat-soluble vitamins: A2500IUD100IUE10mgK110mg
Water-soluble vitamins: B13mgB23.6mgB64mgB125ug
Pantothenic Acid 15mg Niacinamide 40mg Folic Acid 400ugC 100mg
Trace elements: copper 0.3mg iodine 131ug zinc 3.2mg selenium 30~60ug
Molybdenum 19ug Manganese 0.2~0.3mg Chromium 10~20ug Iron 1.2mg
Post time: Aug-19-2022