Nineteenth Century Medical Guide

Chapter 362. 358. Survival: Restarting the Eastern Travel Plan

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([-]) Protein target of nutritional therapy
The high catabolic state after nerve injury is associated with significant proteolysis and muscle loss, resulting in an increased demand for protein. Therefore, it is generally believed that critically ill neurosurgical patients have higher protein requirements than other critically ill patients.But it's still not clear what the optimal protein goal should be, nor the best time to hit the protein energy goal.According to previous recommendations, patients can supplement protein at 1.2-2.0 g kg-1 d-1 [30], more than 50% of which should come from high-quality protein, and can be obtained through the nitrogen balance formula: nitrogen balance (g/24 h) = protein intake (g/24 h)/6.25 - [urea nitrogen in urine (g/24 h) + 4] for evaluation and continuous monitoring.High protein supply was associated with improved nitrogen balance.

高蛋白供给是否改善重症患者的结局仍有争议。近期的荟萃分析表明高蛋白供给可能与营养风险患者的病死率改善相关［31］。多项观察性研究支持高蛋白质供给可改善机体蛋白质平衡、减少机械通气时间和更高的生存率［27，3234］，当蛋白供应>1.3 g· kg-1·d-1时患者生存期可显著改善［22］。

However, the results of several studies have shown that high protein supply does not have a significant impact on clinical outcomes. The results of a clinical RCT published in 2021 suggested that patients who received a higher protein supply [(1.5±0.5) than (1.0±0.5) g·kg-1·d-1] had better clinical outcomes or quadriceps muscle There was no difference in layer thickness [35].A recent multicenter RCT including 120 patients investigated high-protein versus low-protein enteral nutrition formulas (100 g/L vs. 63 g/L). The protein supply was higher (1.52 g·kg-1·d-1 compared with 0.99 g·kg-1·d-1, body mass was calculated as IBW), but the clinical outcome (mortality at 90 days) between the two groups was not the same. No difference [36].There are still some large-scale clinical trials such as EFORT (NCT03160547) in progress, aiming to evaluate the impact of high protein supply and low protein supply on critically ill patients. It is hoped that the latest trial results can give clinicians more guidance information.For non-dialysis patients with impaired renal function, the target value of protein therapy should be analyzed according to the specific condition, and multidisciplinary discussions should be made when necessary.

推荐建议8：现有证据不能给出最佳蛋白质目标的推荐以及达标最佳时机的推荐，神经外科重症患者可在急性期将蛋白质目标设定为1.2~2.0 g· kg-1·d-1。

([-]) Carbohydrate and fat targets for nutrition therapy
1. Carbohydrates and glucose: Carbohydrates are the preferred substrate for energy production during enteral nutrition. Carbohydrates are generally considered harmless, but high carbohydrates may be the main cause of feeding intolerance. Enteral nutrition Other polysaccharide ingredients in the formula may also cause intolerance in susceptible patients. In neurosurgical patients, the incidence of stress hyperglycemia is high, so it is recommended that the energy supply ratio of carbohydrates not exceed 60% [37], and carbohydrates Compounds are often selected from sources with a low glycemic index.

进行肠外营养时，过量的基于葡萄糖的能量供应与高血糖、CO2生成增加、脂肪生成增加、胰岛素需求增加相关，且在减少蛋白质消耗方面没有优势。与富含葡萄糖的肠外营养相关的高血糖症往往需要更高剂量的胰岛素。因此建议静脉葡萄糖给药剂量不应超过5 mg·kg-1·min-1［3839］。

2. Fat and venous lipid: Lipid oxidation provides more than half of the energy required by the liver, heart and skeletal muscle. Although some studies have evaluated the optimal sugar/fat ratio from the perspective of improving nitrogen balance, due to severe neurosurgery patients Alterations in lipid metabolism, the optimal total daily lipid requirement is currently unknown.In addition to the total amount, the composition of the enteral nutrition formula (enteral nutrition formula, EF) should be carefully evaluated during enteral nutrition. The fat composition included should limit but not completely exclude omega-6 fatty acids, and should provide monounsaturated fatty acids, omega-3 fatty acids , reduce saturated fatty acids and avoid trans fatty acids, the recommended dose of essential fatty acids (fatty acid, FA) in accordance with the dietary reference intake.

At the same time, fat absorption is impaired in critically ill patients, and lipid overload may cause immunosuppression and impair lung and liver function.For intravenous lipids, the recommended upper limit of supply is 1 g·kg-1·d-1, and the highest tolerated dose is 1.5 g·kg-1·d-1.The lipid ratio can be adjusted according to the blood triglyceride level and liver function [40].

Recommendation 9: When enteral nutrition is used for neurosurgery critically ill patients, it is recommended that the energy supply ratio of carbohydrates should not exceed 60%. The optimal fat intake is not yet clear, and it is recommended to adjust it according to the blood triglyceride level and liver function.During parenteral nutrition, it is recommended that the dosage of glucose should not exceed 5 mg·kg-1·min-1.Venous lipid (including non-nutritive lipid sources) should not exceed 1.5 g·kg-1·d-1, and lipid overload should be avoided.

[[-]. Enteral nutrition therapy for critically ill patients in neurosurgery]

([-]) Timing of starting enteral nutrition therapy
ASPEN/SCCM (2016) and the "Chinese Expert Consensus on Nutritional Support Therapy for Critically Ill Patients" both recommend starting enteral nutrition within 24 to 48 hours, and enteral nutrition is superior to parenteral nutrition [16, 41].The European Society for Parenteral and Enteral Nutrition recommends that patients with traumatic brain injury start enteral nutrition within 48 hours [42].The European Society of Critical Care[43] suggested that although the current multiple RCT studies cannot draw a conclusion whether the benefits of early enteral nutrition must outweigh the risks, based on expert opinion, the treatment of traumatic brain trauma, ischemic or hemorrhagic stroke , spinal cord injury patients, should start early enteral nutrition.

Delayed enteral nutrition therapy: for uncontrolled shock, hypoxemia, severe acidosis, active gastrointestinal bleeding, gastric retention >500 ml/6 h, intestinal ischemia, intestinal obstruction, abdominal compartment syndrome Symptoms and other conditions should suspend the initiation of enteral nutrition.For patients with severe brain injury undergoing therapeutic mild hypothermia, due to the severe decline in metabolic level and the obvious inhibition of gastrointestinal function by cooling, it is recommended to give low-dose early enteral nutrition, and gradually increase the dose after rewarming.

Recommendation 10: Enteral nutrition therapy should be initiated early (within 24–48 hours after admission to the intensive care unit) for critically ill neurosurgical patients under stable hemodynamic conditions.

([-]) Formula selection for enteral nutrition therapy
1. Whole protein formula versus short peptide formula: Based on the results of an international multi-center cross-sectional study, neurosurgery critically ill patients are often in a low-feeding state, and their daily calorie and protein intake are lower than the prescribed amount. The reasons for this are: Enteral nutrition intolerance, impaired gastrointestinal motility, etc., the most common clinical manifestations are diarrhea and gastroparesis, which will affect the absorption of nutrients, resulting in insufficient energy and calorie intake.The existing ASPEN nutrition guidelines recommend standard whole protein formula as the preferred dosage form of enteral nutrition [30].The short peptide type nutrient solution contains short peptides and medium-chain fatty acids, which can improve gastrointestinal tolerance, especially for patients with gastrointestinal function impairment. Choosing a short peptide formula is easier to digest and absorb, and reduces the incidence of diarrhea.However, the single-center RCT results of enteral nutrition therapy for patients with severe craniocerebral trauma also showed that compared with the whole protein formula, the osmotic pressure of the short peptide formula was higher, and gastrointestinal intolerance also occurred, and the two groups There was no significant difference in the average daily intake of calories and protein between the two groups [44].

2. Diabetic formula vs. standard formula: A survey found that, regardless of whether there is a history of diabetes, the proportion of hyperglycemia in neurosurgery critically ill patients can be as high as 60%.Hyperglycemia is an independent risk factor for severe ICU complications, such as electrolyte disturbance, infection, prolonged hospital stay, and increased mortality.Nutritional formulas for diabetic dosage forms are usually low in sugar and high in monounsaturated fatty acids, and the maltose in the standard formula is replaced with starch that digests slowly.Studies have shown that compared with standard enteral nutrition formula, diabetic formula combined with insulin therapy can effectively control blood glucose levels in patients with severe ischemic stroke [45].

3. Immunomodulatory formula vs. standard formula: In the 2016 ASPEN guidelines, based on a small sample study (40 patients), compared with standard enteral nutrition formula, immunomodulatory formula (mainly containing arginine, glutamine, , omega-3 fatty acids, etc.) can reduce the incidence of infection in patients with traumatic brain trauma [30]. In the prospective RCT carried out by Rai et al[46], patients with severe TBI were randomly divided into two groups to receive enteral nutrition of immune formula and standard formula, and the results showed that the inflammatory index (IL-6) of patients receiving immune formula was significantly reduced, and at the same time, anti-inflammatory Oxidation index (glutathione) was significantly increased; in addition, the total protein level of patients in the immune formula group was also significantly increased.In a single-center RCT for a variety of neurosurgical severe diseases, Chao et al[47] found that compared with standard enteral nutrition formula, the CD4+ T lymphocyte count and CD4+/ The proportion of CD8+ was significantly increased, the serum interferon-γ was significantly increased, and the levels of inflammatory factors such as TNF-α, IL-6, IL-8 and IL-10 were significantly reduced; thus, the immune-enhancing enteral nutrition formula can significantly Improving the immune status of critically ill neurosurgical patients.In another retrospective study, Painter et al. [48] found that compared with standard enteral nutrition formula, immune-boosting formula could reduce the incidence of bloodstream infection, but had no effect on lung infection and urinary tract infection. Significant differences.

4. Mixed formula with added dietary fiber: severe neurosurgery patients usually have poor gastrointestinal function tolerance. When the patient has persistent diarrhea, enteral nutrition can be replaced with a mixed formula containing dietary fiber.When choosing a dietary fiber supplement, poorly soluble fibers can lead to clogged feeding tubes.Higher soluble fibers, such as partially hydrolyzed guar gum, wheat dextrin, inulin or fructo-oligosaccharides, are less likely to clog feeding tubes when they dissolve without being gelatinous.Supplementation of soluble dietary fiber can reduce the incidence of clinical diarrhea [49, 50, 51].Soluble dietary fiber uses intestinal probiotics to ferment to produce short-chain fatty acids, promotes the growth of intestinal beneficial bacteria, and regulates intestinal microecology.

Recommendation 11: Entire protein nutritional dosage forms can be selected for enteral nutrition therapy for neurosurgery critically ill patients, and short peptide dosage forms can be selected for patients with gastrointestinal function impairment.

Recommendation 12: For patients with diabetes or hyperglycemia, the selection of diabetic enteral nutrition formula can help improve blood sugar control in the acute phase.

Recommendation 13: For patients with a higher risk of infection, an immunomodulatory enteral nutrition formula can be used.

Recommendation 14: For critically ill neurosurgical patients with persistent diarrhea, a mixed formula containing dietary fiber may be considered.

([-]) Feeding route of enteral nutrition therapy
Nasogastric tube feeding can promote normal physiological stimulation of the gastrointestinal tract, and is technically simple and easy to implement, while post-pyloric feeding requires some experience in tube placement, which may delay the timing of starting enteral nutrition.In addition, an international multi-center observational study of 353 1 neurosurgical critically ill patients (including cerebral hemorrhage, subarachnoid hemorrhage, craniocerebral trauma, intracranial infection, stroke, epilepsy, and neurotumor) in 691 ICUs , to assess the effects of gastric feeding and intestinal feeding on nutritional and clinical endpoints.It was found that although patients in the gastric feeding group were more likely to interrupt enteral nutrition due to gastrointestinal complications, they could better accept adequate calorie feeding; There was no statistically significant difference between other important clinical endpoints such as the proportion of patients [52].Therefore, nasogastric tube feeding is recommended as the preferred route of enteral nutrition.

Postpyloric feeding reduces the incidence of pneumonia in populations at high risk of aspiration.However, severe neurosurgery patients have a high proportion of disturbance of consciousness, weak airway protection, and a high proportion of mechanical ventilation, which is a high-risk group for aspiration.In an RCT of enteral nutrition in patients with severe TBI who were randomly divided into transgastric tube feeding and postpyloric feeding, the results of the study found that compared with gastric tube feeding, postpyloric feeding could significantly reduce The incidence of pneumonia [53].A meta-analysis compared the effects of post-pyloric feeding and gastric feeding on the incidence of pneumonia and other important prognostic endpoints in patients with severe TBI. A total of 5 patients were included in 325 RCT studies. It was found that compared with gastric feeding, post-pyloric feeding Feeding can significantly reduce the incidence of aspiration pneumonia and ventilator-associated pneumonia [54].Therefore, postpyloric feeding is feasible for patients with high risk of aspiration who are intolerant to nasogastric feeding.

Recommendation 15: Nasogastric tube feeding is the preferred way of enteral nutrition.For patients with intolerance to nasogastric tube feeding and high risk of aspiration, post-pyloric feeding is feasible in qualified centers.

([-]) Feeding methods of enteral nutrition therapy
Although continuous feeding is different from the intestinal physiological mode, continuous feeding causes fewer complications in the gastrointestinal tract and respiratory tract, and can achieve the goal of nutritional support earlier.Compared with continuous feeding, intermittent feeding is more in line with physiological characteristics and can promote protein synthesis, but it also increases the risk of high gastric residual volume (GRV), diarrhea and aspiration.

In 2021, the latest meta-analysis results including 14 trials with a total of 1 025 critically ill patients suggested that compared with continuous feeding, intermittent feeding led to an increased risk of feeding intolerance, high GRV, and errors occurred when the duration was > 1 week. increased risk of smoking [55].A number of clinical studies have shown that continuous feeding can provide more enteral nutrition, and the probability of gastrointestinal intolerance and feeding interruption is less [56, 57, 58].

Recommendation 16: Continuous pumping is recommended for enteral nutrition in critically ill neurosurgery patients.

(End of this chapter)