腸內(nèi)營養(yǎng)的選擇

1、第二節(jié) 腸內(nèi)營養(yǎng)的選擇進行腸內(nèi)營養(yǎng)支持時，需根據(jù)預期營養(yǎng)支持的時間、腸道功能的受損程度、發(fā)生吸入性肺炎的危險性 及病人的病情和營養(yǎng)狀況，決定腸內(nèi)營養(yǎng)方式和制劑。一、病人的選擇If the GI tract is functional, it should be used for enteral nutrition (EN), even if only a small amount can be tolerated.Oral intake is encouraged once a speech pathologist has determined the patient is not at hi

2、gh risk for aspiration.Nasoenteric devices, preferably postpyloric, are preferred if EN is not expected to persist past 30 days. Percutaneousgastrostomy or jejunostomy devices are placed if EN is expected beyond 30 days.一般認為當病人胃腸道功能不健全、不能吸收足夠的營養(yǎng)時，腸外營養(yǎng)能迅速補充營養(yǎng)，改善營養(yǎng)狀 況，拯救病人的生命。但原那么上講，只要病人胃腸道功能存在或局部存在，并

3、具有一定的吸收功能，就應 該首選腸內(nèi)營養(yǎng)。只有真性腸麻痹、機械性腸梗阻及嚴重腹腔感染時，才考慮采用腸外營養(yǎng)。二、時機的選擇腸內(nèi)營養(yǎng)的時機選擇很重要。危重病人或嚴重創(chuàng)傷病人一旦血液動力學穩(wěn)定，酸堿失衡和電解質(zhì)紊亂 得到糾正，就應立即開始腸內(nèi)營養(yǎng)。一般嚴重創(chuàng)傷后2448小時內(nèi)給予腸內(nèi)營養(yǎng)效果最正確。對于擇期手術的病人，如果存在營養(yǎng)不良，手術前就應該采用腸內(nèi)營養(yǎng)，改善病人的營養(yǎng)狀況和免疫功能，提高手術 耐受力，降低手術風險，減少手術并發(fā)癥。三、置管方式的選擇Access routes for enteral feeding vary according to the individual patie

4、nt. In deciding which route to use, theanticipated length of feeding and the presence of delayed gastric emptying are two major considerations. Access to the GItract via the nasal route such as nasogastric, nasoduodenal, or nasojejunal tubes are usually short term (less than 6-8weeks). These tubes c

5、an be placed at the bedside. When enteral feeding is anticipated for a longer period of time anenterostomy tube should be considered. This is a more invasive category of enteral feeding where the tube accesses the GItract through the abdominalwall. Thisprocedure can be carried out in an endoscopy un

6、it, radiology department or in theatre.1.對病人的損傷程度損傷小、簡單平安是置管最重要的原那么。目前臨床應用最廣泛的是經(jīng)鼻置鼻胃 管、鼻十二指腸管或鼻空腸管。對于有腸內(nèi)營養(yǎng)指征，上消化道無梗阻，營養(yǎng)支持后仍可恢復自然經(jīng)口進 食者，應盡可能采用經(jīng)鼻置管。只有口、咽、鼻、食管梗阻或因疾病原因不能恢復經(jīng)口進食，或雖然能恢 復經(jīng)口進食但需時較長、發(fā)生吸入性肺炎危險性大的病人才考慮造痿置管。2.營養(yǎng)支持所需時間需長期管飼者宜用胃造口或空腸造口置管，估計時間較短者宜采用經(jīng)鼻置管。時間長短受病人疾病、營養(yǎng)狀況、醫(yī)療監(jiān)護條件和所用鼻飼管質(zhì)地等影響。3.胃腸道功能 胃腸道

7、功能受損程度影響腸內(nèi)營養(yǎng)方式的選擇，嚴重受損者不能應用腸內(nèi)營養(yǎng)。胃腸 功能差、需持續(xù)滴入營養(yǎng)液以及有較大誤吸危險者，宜用胃或空腸造口置管。經(jīng)腹手術的病人，如營養(yǎng)狀 況差、手術創(chuàng)傷重，或估計術后發(fā)生胰痿、膽?zhàn)?、胃腸吻合口痿等可能性大者，應在術中作空腸造口置管， 用于病人較長時間的營養(yǎng)支持。四、營養(yǎng)液輸注方法的選擇1.營養(yǎng)液輸注時間的選擇根據(jù)病人營養(yǎng)需要及其耐受程度而定。一般使用間歇輸注，病人可以有較大的活動度，適用于胃腸道功能較好的病人。對于胃腸道功能差、嚴重營養(yǎng)不良、并發(fā)癥多、高應激狀態(tài) 或躁動的病人，可以給予連續(xù)性輸注，一般為連續(xù)喂養(yǎng)20小時、間歇4小時，以讓消化系統(tǒng)有足夠的時間休息。對于消

8、化、吸收功能非常差或使用抑酸劑的病人甚至可以24小時持續(xù)喂養(yǎng)。The length of time which enteral feeding is given depends on the patients needs andtolerance as well as local practices. If a patient requires full nutritional support it is usual to feed over about 20h with a 4-hrest period to allow the gastric acidity to return to no

9、rmal. If the patient is given antacids, the feeding can continue over24h if required as the gastric acidity is already altered.2.營養(yǎng)液輸注速度的選擇病人由腸道曠置到重新耐受腸道內(nèi)營養(yǎng)物質(zhì)需要一段時間，因此剛開始輸 注腸內(nèi)營養(yǎng)液時應遵循低滲、少量、慢速的原那么。一般間歇性輸注病人開始腸內(nèi)營養(yǎng)時，營養(yǎng)液的滴速宜控制在2550ml/h。如病人耐受，可每8小時增加2550ml , 16小時后可增加100ml , 24小時可 增加150ml左右。如病人不耐受，滴速增加的幅度應

10、減慢。連續(xù)性泵輸注的病人可勻速輸注，最初滴速 亦為2550ml/h，每8小時增加2550ml，最終的平均滴速宜為100ml/h左右，最高可至200ml/hc調(diào)整滴速的依據(jù)是胃內(nèi)潴留物的檢查。If a patient has not been fed in the last 5 days, feedings should begin as low volume, continuous flow feedings in therange of 25 to 50ml/hour . Dependingon the patientstolerance, the rate can be titrated

11、upward by 25ml every 8 to 12 hours. Residual volume in stomach should be monitoredevery 2 to 4 hours.If the patient is tolerating enteral feeding, the length of time that they are fed can be reduced, and the rate mustincrease to make sure all requirements are met. In situations where adult patients

12、are well established on feeding, feedscan be administered at a rate of up to 200ml/h by pump or bolus.五、營養(yǎng)制劑的選擇胃腸道功能良好者可用管飼滴注含完整蛋白的完全膳食，如勻漿膳、混合奶等，小兒可給予嬰兒膳。 如果口咽無梗阻，經(jīng)一段時間管飼營養(yǎng)支持后病情緩解，可逐漸恢復自然飲食。但對口、咽、食管有梗阻， 或因疾病、手術而吞咽功能受損者，那么需長期管飼完全膳食。消化吸收功能較差者，可以采用要素制劑。 詳見下一節(jié)。六、能量、氮量及液體量的選擇Since the loss of protein st

13、ores directly affects body function, it is important to administersufficient amounts of energy and protein.1.能量腸內(nèi)營養(yǎng)支持的實施首先要確定病人的能量需要量。In the past, hyperalimentation (the delivery of energy in excess of requirements) was thought to be efficient in improvingnutritional status. However, hyperalimentati

14、on has been shown toinduce severe metabolic abnormalities such as hyperglycemia, hyperlipidemia, and increased carbon dioxide production.Patients receiving nutritional support should be fed to their requirements.In clinical practice, selected methods for estimating basal energy requirements are show

15、n in Box 9.1.1. A frequentlyused simple guideline for estimating the daily energy needs of a patient is 25-35 kcal/kg body weight.Box 9.1.1 Selected methods for estimating energy requirementsHarris-Benedict equation (estimates basal energy expenditure)Male:(13.75 X W)+(5.0 X H)+(6.76 X A)+66.47Femal

16、e:(9.56 X W)+(1.85 X H)-(4.68 X A)+655.1where W is weight in kilograms; H is height in centimeters; A is age in years.To predict total energy expenditure (TEE), add an injury/activity factor of 1.2-1.8depending on the severity and nature of illness.Ireton-Jones energy expenditure equationsObesityIEE

17、 =606S+9W+12A+400V+1444Spontaneously breathing patientsEEEs =629-11A+25W-609OVentilator-dependent patientsEEEv =1925-10A+5W+281S+292T+8518EEE is in kcal/day; subscript V indicates ventilator dependent; subscript S indicates spontaneously breathing.S: sex (male=1, female=0)V: ventilator support (pres

18、ent=1, absent=0)T: diagnosis of trauma (present=1, absent=0)B: diagnosis of burn (present=1, absent=0)O: obesity 30% above ideal body weight from 1959 Metropolitan Life Insurance tables(present=1, absent=0)In the clinical situation, additional disease-associated factors should be taken intoaccount d

19、uring the calculation of the required energy needs. These include disease stress factor, activity factor, andtemperature factor. Energy and nutrient losses from malabsorption should be taken into account when present.能量的供給并非多多益善，不僅要考慮病人的能量消耗，還要考慮病人的實際代謝能力。1970年，Kinney和他的研究小組發(fā)現(xiàn)選擇性手術并不增加能量消耗，只有重大創(chuàng)傷或非常

20、嚴重的敗血癥病人，其 能量消耗會在一定時間內(nèi)增加20%40% o隨著護理和鎮(zhèn)痛技術的提高，與創(chuàng)傷有關的代謝負荷出現(xiàn)下降的趨勢。因此，病人的能量供給應因人因時而異。對應激期的病人，尤其是危重病人，能量補充宜維持 體重而非增加體重，能量供給量應以能維持能量代謝平衡、氮平衡為宜。而在恢復期那么應在能量消耗的基 礎上，考慮合成代謝所需，以利于機體的修復。病人能量供給量包括根底能量消耗、體力活動消耗和疾病應激時的能量消耗?？筛鶕?jù)Harris-Benedict公式確定BEE(見Box9.1.1)。再根據(jù)BEE、活動系數(shù)、應激系數(shù)、體溫系數(shù)來確定總能量的消耗，即 總能量需求=BE成活動系數(shù)X應激系數(shù)X體溫系

21、數(shù)?；顒酉禂?shù)：臥床為1.2，床邊活動為1.25,正常輕 度活動為1.3。應激系數(shù)見表9-2-1。體溫系數(shù)：正常時為1.0，每升高1 C增加消耗10%。表9-2-1不同疾病狀態(tài)下應激系數(shù)疾病應激系數(shù)疾病應激系數(shù)中等程度饑餓0.851.00嚴重感染或多發(fā)性創(chuàng)傷1.30 1.55術后(無并發(fā)癥)1.001.05燒傷(10% 30%體外表積)1.50癌癥1.101.45燒傷(30% 50%體外表積)1.75腹膜炎1.051.25燒傷(50%體外表積)2.00長骨骨折1.151.30引自：臨床腸外與腸內(nèi)營養(yǎng)?，蔣朱明、蔡威主編，2000年際上，病人實際能量的消耗通常低于由經(jīng)典的公式計算出來的數(shù)值。大局部

22、病人(包括ICU病人)的 能量消耗一般不高于8.36MJ/d(2000kcal/d )。能量的計算還可按(105146kJ)25 35kcal/kg估算。2.蛋白質(zhì) 正常人每日蛋白質(zhì)的需要量一般為0.8g/kg。營養(yǎng)治療時為滿足蛋白質(zhì)需要可增至每日1.5g/kg,正?；蜉p度營養(yǎng)不良者按實際體重計，重度營養(yǎng)不良者按平時體重計，超重者那么需按理 想體重計。對于危重病人，能夠滿足蛋白質(zhì)合成需要、糾正負氮平衡的理想攝入量為1.51.7g/kg。由于高蛋白質(zhì)飲食會增加肝、腎負擔，蛋白質(zhì)的攝入量不宜超過2.0g/kg。如以能量計算，每日蛋白質(zhì)攝入量應占全天總能量的15%左右。另外，非蛋白質(zhì)能量與氮量之比(

23、能氮比)以(627836kJ )150200kcal:1g較為適宜。能量需要下降時，能氮比也應下降。如病人需要較多蛋白質(zhì)，那么能氮比需降至(418502kJ ) 100120kcal:1g才能滿足蛋白質(zhì)需要， 肝衰、腎衰病人以(1.051.88MJ ) 250 450kcal:1g為宜。Simply providing an excess of energy will not promote a positive N balance if the protein intake is less thanadequate. Whereas in the diseased patient prote

24、in synthesis can be stimulated by feeding, protein intake cannot influencewhole body protein breakdown that occurs during inflammation.When protein accretion is the goal of nutritional therapy, the protein intake will have to be raised to about 1.5g/kgper day. In severely ill patients and increased

25、protein intake of 1.5-1.7g/kg body weight per day (normally 0.8g/kg bodyweight/day) optimally stimulates protein synthesis, resulting in the least negative nitrogen balance. Since there may be adiminished ability of the kidney and liver to tolerate a high amino acid load, the protein intake of patie

26、nt should ideally notexceed 2 g/kg per day. Expressed as a percentage of the energy given, the protein intake should be about 15%.3.液體量During disease, fluid and electrolyte balances can become disturbed. Overloading of fluids and electrolytes mayimpair gastric motility and delay the use of the enteral route for feeding.