Early stage of severe acute pancreatitis (SAP) mainly shows systemic inflammatory response (SIRS), and 20% of patients die from multi-system organ failure (MODS) at this stage; in the second stage of the disease, 40-70% of patients with pancreatic necrosis develop infection. Infectious necrosis has a mortality rate of more than 30%, and infection-associated multi-organ failure (MOF) is the most important life-threatening complication, with a mortality rate of 20-50%.
Eighty percent of all deaths from severe pancreatitis are due to widespread infectious complications. Gastrointestinal dysfunction in severe acute pancreatitis is manifested by (1) decreased gastrointestinal motility, abdominal distension, and abdominal hypertension; and (2) decreased barrier function, increased endotoxin, and bacterial translocation.
In recent years, it has been recognized that the translocation of intestinal bacteria into the necrotic tissue of the pancreas in patients with acute pancreatitis is the cause of infection and a series of subsequent changes, and that ensuring the blood supply, oxygen supply and enteral nutrition of the intestinal mucosa is the main measure to prevent damage to the intestinal barrier function.
The metabolic characteristics of SAP patients: hypermetabolism, hypercatabolism, hyperglycemia, hyperlipidemia, hypoproteinemia, hypocalcemia and hypomagnesemia. the increase of energy consumption in SAP patients is prominent. In the absence of infection SAP is usually increased by 20-30% and with infection by about 50%. The implication for clinical management is that early clinical decisions such as fluid resuscitation, enteral nutrition, and selective bowel decontamination may be a viable approach to reduce lethality and improve quality of survival.
The purpose of nutritional support
1, To reduce pancreatic fluid secretion and prevent the continued development of peripancreatic inflammation.
2.Increased energy expenditure in SAP and replenishment of adequate nutrients to avoid inadequate nutrient intake that may cause additional catabolism.
3, SAP abnormal nutrient metabolism, such as hyperglycemia, hypoproteinemia, low calcium, low magnesium, etc., need to be corrected by proper nutrient support.
4, almost all SAP patients have varying degrees of intestinal paralysis, gastrointestinal function takes a considerable amount of time to gradually recover, nutrients must be supplemented through appropriate means.
5. In recent years, it has been found that early EN in SAP patients can help improve the intestinal mucosal barrier and reduce complications such as infections.
Nutritional support strategies in different periods
Acute reaction period.
Occurs in about 2 weeks, often with MODS and hemodynamic instability, the main contradiction SIRS, MODS, the focus of treatment is under intensive care, early fluid resuscitation, organ support, and the management of serious complications such as ACS, while inhibiting the secretion of pancreatic fluid.
Metabolic characteristics.
It must be clearly recognized that at this time high metabolism and high catabolism are almost inevitable, and the most prominent contradictions are hyperglycemia, hyperlipidemia and rapidly emerging hypoproteinemia. Due to the disruption of metabolic hormones and the role of inflammatory mediators, there is poor tolerance to exogenous nutrients. patients with SAP often have a good original nutritional status and the contradiction of inadequate nutrient intake is not prominent.
Nutritional support strategies.
The goal of nutritional support is to correct metabolic disorders and reduce protein loss to a reasonable level as much as possible, without either causing additional catabolism due to inadequate nutrient intake or adding an inappropriate load to the respiratory circulation and liver due to unreasonable nutritional support.
The nutritional pathway is based on PN. Caloric intake is around 1.0-1.1 times REE or 20 kcal/kg*d. For patients without hyperlipidemia, fat milk can be applied with good fat profile, sugar:fat up to 5:5, lower nitrogen amount 0.2 g/kg*d, and adequate vitamin and trace element supplementation. After one week, gastrointestinal function gradually recovered, abdominal distension was reduced and EN gradually started.
Timing of nutritional support.
After hemodynamic and internal environment stabilization. early SAP (within 2 weeks), there is recovery of gastrointestinal function, EN support via nasojejunal tube can not increase pancreatic secretion, reduce inflammatory response, reduce TNA time, and reduce peripancreatic tissue necrosis.
Systemic infection period.
About 2 weeks-2 months, mainly manifested by widespread bacterial and fungal infections in the peripancreatic and retroperitoneum, SEPSIS and MODS. the focus of treatment is anti-infection and drainage of the peripancreatic and retroperitoneum.
Metabolic features.
There remains severe metabolic derangement, most notably characterized by hypermetabolism, hypercatabolism, persistent negative nitrogen balance, severe depletion of muscle fat, more severe hypoproteinemia, hyperglycemia, and hyperlipidemia than before usually mild. There is also varying degrees of organ insufficiency.
Nutritional support strategies.
Total caloric intake at 1. 2 times REE, or about 25-30 kcal/kg*d, nitrogen 0.2-0.24/kg*d, sugar/lipid ratio up to 5:5 if fat profile is good. transnasal jejunal line EN is the mainstay.
Recovery period.
After 2-3 months, the main clinical manifestations are retroperitoneal or intra-abdominal residual pus cavity, often with poor drainage and long-lasting sinus tracts, but the infection is well controlled.
Metabolic features.
Malnutrition, but gradual return to nitrogen homeostasis and good tolerance of the organism to exogenous nutrients.
Nutritional support strategies.
The recovery of the function of the patient’s organ systems is closely related to the recovery of the nutritional status. The nutrients provided must exceed the nutrients consumed by the organism. The total caloric intake is 1.2-1.5 times REE, or about 30-35 kcal/kg*d, nitrogen 4-0.48 g/kg*d, sugar/lipid ratio up to 6:4. EN (transnasal jejunal tube) is the mainstay, and the transoral diet is gradually overtaken.
Special problems of SAP nutritional support
1. Patients with hyperlipidemic pancreatitis need special correction of hyperlipidemia so that triglycerides (TG) are below 5.65 mmol/L.
Measures: discontinuation of drugs causing hyperlipidemia, prohibition of fat emulsion, blood prize replacement or lipid separation if necessary, prohibition of fat emulsion input when TG > 4.4 mmol/L and fat infusion is not contoured 6 h later.
Studies have proved that: intra-duodenal fat infusion has significantly stimulated pancreatic fluid secretion. However, intravenous infusion of fat emulsion does not increase the secretion of pancreatic juice. Fat emulsion is used as a mixed energy source in SAP and no significant adverse consequences have been found. Its high caloric density, provision of essential fatty acids, and low osmolality can provide 30-50% of non-protein calories by it for patients with combined ARDS or hyperglycemic SAP. The use of fat emulsion in TNA can avoid the adverse effects of fat emulsion.
2.Gastrointestinal impairment and enteral nutrition in SAP patients
Recent observations have shown that: within 48 hours of SAP onset, a nasal-intestinal tube was placed under endoscopic guidance below the Treitz ligament and infused with enteral nutrition, which was also well tolerated by patients and no adverse clinical reactions were found.
Inappropriate EN leads to recurrent disease, the main reasons: the nutrition tube is located in the stomach or duodenum, gastrointestinal function has not recovered, or with intestinal obstruction, too fast and too much infusion speed, gastrointestinal intolerance, combined with intra-abdominal hypertension.
3, the application of EN in the acute phase of SAP should follow the principles
(1) Stable hemodynamics and internal environment to ensure no intra-abdominal hypertension.
(2) Gastrointestinal function has been restored to ensure that there is no intestinal obstruction.
(3) Confirmation that the nutrient tube is located in the jejunum.
(4) Infusion rate is gradual, and if abdominal pain and distension worsen, stop in time.