Surgical nutrition support therapy was born in the 1960s and was included in the major medical advances of the 20th century along with the development of antibiotics, advances in anesthesiology, and intensive care and organ transplantation. Total parenteral nutrition is the use of complete nutritional elements directly into the bloodstream by the parenteral route to provide nutritional support. In recent years, with the development of medical technology, TPN has undergone profound changes from theoretical to clinical, and has been generally valued and widely used. Experimental studies and clinical applications have confirmed the important role of TPN in correcting ammonia balance, accelerating wound healing and improving resistance, which has effectively improved the success rate and survival rate of surgery and reduced the occurrence of complications in clinical treatment, and has become an indispensable part of surgical treatment.
The nutritional elements contained in TPN include amino acids, fats, sugars, vitamins, trace elements, electrolytes and water. Due to the complexity of the components, review of the prescription is key to the ability to configure a stable infusion. Nutritional status assessment is the basis of clinical nutritional support, which not only can understand the degree of malnutrition of patients and clarify whether and to what extent nutritional support is needed, but also is a means to monitor the effect of treatment. Correct nutritional assessment is the prerequisite for the formulation of reasonable parenteral nutrition support, which requires clinicians to make correct assessment of patients’ nutritional status before and during TPN to provide a comprehensive and scientific basis for the formulation of TPN program, so that the prescription can meet patients’ requirements and avoid excessive nutrition at the same time.
The mode of intravenous nutritional support is individualized administration, and clinicians generally adjust the basic formula according to the actual situation of patients: for example, the dosage of electrolytes, vitamins and trace elements is increased or decreased as appropriate according to the biochemical tests of patients; the dosage of insulin in TPN is adjusted according to the situation of patients’ blood glucose or urine sugar, and diabetic patients may suffer from carbohydrate and fat metabolism disorders due to insufficient insulin secretion. Therefore, while limiting the amount of glucose added as appropriate, the dosage of insulin should be increased appropriately, generally 1U of insulin per 4g of sugar is appropriate.
In addition, we should consider the total amount of fluid, non-protein calories, total nitrogen, heat to nitrogen ratio, osmolality and pH value in the prescription; we should also pay attention to the amount of nutritional components and check whether there are contraindications to the combination. (such as the decrease of glucose utilization ability of the body and tissues, the obvious decrease of insulin, the protein metabolism, the increase of energy requirement during stress, the negative ammonia balance, etc.). Therefore, when applying parenteral nutrition in general, under the premise of reducing calories, the dosage of glucose should be reduced first, and fatty milk should be used to provide 25%-40% of non-protein energy, while the intake of amino acids should be increased, so that the ratio of non-protein calories to nitrogen will decrease.
The standard prescriptions provided in the literature have a large general range to meet the needs of most patients, and some patients with high metabolic catabolism or special needs can design individualized prescriptions according to their conditions. Modern clinical nutrition has adopted new measures to further improve nutritional preparations to enhance patient tolerance. To meet the needs of nutritional therapy, special nutritional substrates are provided to special patients to enhance their immune function, improve intestinal barrier function, and increase the antioxidant capacity of the body. New special nutritional preparations include: ① fat emulsions: including structural fat emulsions, long-chain and medium-chain fat emulsions and fat emulsions rich in ω-3 fatty acids, etc.; ② amino acid preparations: including arginine, glutamine dipeptide and taurine, etc. Jui Jianhua, Department of General Surgery, Gaomi People’s Hospital
The preparation of TPN is a process of strict aseptic operation. The preparation room must have purification conditions. The preparation personnel should change their clothes, hats, masks and shoes when they enter the preparation room, and the number of times they enter and leave the preparation room should be reduced during preparation, and non-preparation personnel are not allowed to enter.
The preparation room must be cleaned and disinfected before the preparation every day, wipe the purification table with 75% alcohol, start the table for 20min, and disinfect with ultraviolet light for 30~60min before starting to work. The required items should be wiped with alcohol. Before preparation, you should check the medical prescription again, check the color, clarity, sealing performance and expiration date of drugs. All drugs should be filled into the infusion bag in order by airtight type. the order of preparation of TPN solution is.
① Add electrolyte solution into glucose solution and amino acid solution, respectively.
② Add water-soluble vitamins into glucose solution.
③Add the fat-soluble vitamins into the fat emulsion.
④Mix glucose solution and amino acid solution into 3L nutrition bag.
⑤ Finally, slowly mix the fat emulsion into the 3L nutrition bag.
Liquid dispensing should be done at one time without interruption, and constantly shake to make the mixture uniform, and focus on closing the catheter that is not connected with liquid when adding liquid. Clinical drugs should be added with the interface, routinely disinfected, and attention should be paid to contraindications when adding drugs, especially new drugs. After the dispensing is finished, label the surface of the 3L infusion bag with the name, drug name and dosage, and configuration time. Nutrient solution should be used up within 24 h. It is strictly forbidden to use it with heating, and the drip tube set should be added with a 0.22 μm terminal de-bacterization filter when input.
Since the nutrient solution of TPN enters the body tissues and organs directly with blood through the intravenous vessels, the quality requirements are very strict. The caloric energy supplied is mainly supplied by glucose and emulsified fat, and the nitrogen source is supplied by amino acids. In order to prevent the decomposition of amino acids and ensure the effective use of amino acids, the ratio between various amino acids should be appropriate, and the ratio of heat to nitrogen is generally 150-200kCal:1g. The stability of all-in-one nutrition solution is the most important clinical concern, and the key lies in whether the physical and chemical properties of various nutrition agents will change after mixing to affect the safety and efficacy of their clinical application.
Over the years, a large number of experiments and clinical studies have proved that if TNA solution is prepared and infused according to certain protocols, it can be safely and effectively applied for a long time and continuously. It has been found that pH, glucose solution, electrolytes and amino acid solution can affect the stability of TNA. the composition of TPN is complex, the preparation protocol is strict, and the stability of many substances such as fatty milk, vitamins, trace elements, etc. in the mixture should be taken seriously to ensure the quality of the liquid.
The total concentration of glucose in the prescription should be between 5% and 20% to avoid fat coagulation and to preserve the stability of TPN. Because cations can neutralize the negative charge of phospholipids in fat particles, causing their particles to aggregate and fuse in close proximity to each other, eventually leading to water-oil stratification, the concentration of electrolytes should be controlled in TPN preparation, and the concentrations of K+, Na+, Ca2+, and Mg2+ should be less than 100, 200, 3.4, and 6.8 mmol/L, respectively. pH should be adjusted in consideration of the need for preparation stability within the The osmotic pressure must be similar to the osmotic pressure of plasma, too high osmotic pressure is more stimulating to blood vessels and difficult for patients to accept. It must be sterile, non-pyrogenic and non-toxic, and the particles must not exceed the pharmacopoeia regulations and must not contain allergenic substances.
Before and during the use of TPN, patients should be closely and meticulously monitored by comprehensive clinical observation and laboratory monitoring. In addition to daily recording of incoming and outgoing fluid volume and paying attention to systemic reactions, routine blood, electrolytes, blood glucose, partial pressure of oxygen, plasma protein, ketone bodies and urine biochemistry should be observed, and the formula should be adjusted in a timely manner according to the dynamic changes of metabolism in the patient’s body to prevent the occurrence of complications. During the infusion operation, strict disinfection should be carried out to prevent infection, because once the infusion is infected with bacteria, its reproduction rate is quite fast, and many patients with severe Gram-negative bacterial infections and in a stressful state, the vast majority of them will develop endotoxemia, so it is necessary to strictly infuse the process.
At the same time, protect the input catheter, do a good job of catheter care, the catheter can only be used as a special entrance for the input of nutrient solution, can not be used for blood sampling, monitoring intravenous pressure, drug delivery, blood transfusion and other purposes. If a patient has feverish reaction to intravenous nutrient infusion, the cause should be immediately identified, and if it is caused by nutrient infusion or catheter infection, the infusion should be stopped immediately and corresponding anti-infection and other resuscitation measures should be given. The application of terminal sterilization filter can effectively remove bacteria and particles from TPN, which can reduce the occurrence of complications and avoid pulmonary vascular embolism caused by the input of large amount of particles, and increase the safety of TPN. However, it should be noted that filters do not remove viruses and some heat sources, and strict aseptic operation and meticulous clinical care should not be neglected because of the use of filters.
This practice has largely alleviated the problem of hyperosmolarity when various components are used individually, making the infusion of nutrition more comprehensive and more conducive to the body’s absorption, and has improved the convenience of operation and reduced the chance of infection. The problem of peripheral veins not being able to tolerate hypertonic, low pH fluids has been solved.
In addition, TPN preparations also developed rapidly, saving the lives of many patients with nutritional disorders, but the understanding of its adverse effects also gradually became clear. Therefore, measures to promote intestinal function compensation, including intravenous administration of glutamine dipeptide, recombinant human growth hormone and oral low-fat fiber-containing food, are added to enhance the protection of the intestinal mucosa, strengthen the immune response and reduce the chance of infection. In addition, complications of TPN include possible collateral damage, air embolism, bloodstream infection caused by central venous puncture and cannulation, metabolic disorders, gallbladder stones, and elevated liver enzyme profile caused by long-term TPN. Therefore, the clinical application of TPN must strictly grasp its indications.
The formulation and clinical application of TPN in China has a history of more than 30 years, and its formulation protocol, quality and ratio of nutritional elements have become more scientific and perfect. Its role has not only been widely affirmed by various clinical departments, but also has become one of the important measures to save various critical patients. Clinical practice over the years has shown that TPN has important significance in shortening the healing time of surgery, improving the cure rate of disease, promoting early recovery or improving the quality of survival of patients.