1、第二節 腸內營養的選擇進行腸內營養支持時，需根據預期營養支持的時間、腸道功能的受損程度、發生吸入性肺炎的危險性 及病人的病情和營養狀況，決定腸內營養方式和制劑。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 determinedthe patient is not at hi

2、gh risk for aspiration. Nasoentericdevices, preferablypostpyloric,are preferredif 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時，腸外營養能迅速補充營養，改善營養狀況，拯救病人的生命。但原則上講，只要病人胃腸道功能存在或部分存在，并具有一定的

3、吸收功能，就應 該首選腸內營養。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。二、時機的選擇腸內營養的時機選擇很重要。危重病人或嚴重創傷病人一旦血液動力學穩定，酸堿失衡和電解質紊亂 得到糾正，就應立即開始腸內營養。一般嚴重創傷后2448小時內給予腸內營養效果最佳。對于擇期手術的病人，如果存在營養不良，手術前就應該采用腸內營養，改善病人的營養狀況和免疫功能，提高手術 耐受力，降低手術風險，減少手術并發癥。三、置管方式的選擇Access routes for enteral feeding vary according to the individual patient. In

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

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

6、t, radiology department or in theatre.1. 對病人的損傷程度損傷小、簡單安全是置管最重要的原則。目前臨床應用最廣泛的是經鼻置鼻胃管、鼻十二指腸管或鼻空腸管。對于有腸內營養指征，上消化道無梗阻，營養支持后仍可恢復自然經口進 食者，應盡可能采用經鼻置管。只有口、咽、鼻、食管梗阻或因疾病原因不能恢復經口進食，或雖然能恢 復經口進食但需時較長、發生吸入性肺炎危險性大的病人才考慮造瘺置管。2. 營養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鼻置管。時間長短受病人疾病、營養狀況、醫療監護條件和所用鼻飼管質地等影響。3. 胃腸道功能胃腸道功

7、能受損程度影響腸內營養方式的選擇，嚴重受損者不能應用腸內營養。胃腸功能差、需持續滴入營養液以及有較大誤吸危險者，宜用胃或空腸造口置管。經腹手術的病人，如營養狀況差、手術創傷重，或估計術后發生胰瘺、膽瘺、胃腸吻合口瘺等可能性大者，應在術中作空腸造口置管， 用于病人較長時間的營養支持。四、營養液輸注方法的選擇1. 營養液輸注時間的選擇根據病人營養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、嚴重營養不良、并發癥多、高應激狀態或躁動的病人，可以給予連續性輸注，一般為連續喂養20 小時、間歇4 小時，以讓消化系統有足夠的時間休息。對于消化

8、、吸收功能非常差或使用抑酸劑的病人甚至可以24 小時持續喂養。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-h rest period to allow the gastric acidity to return to n

9、ormal. If the patient is given antacids, the feeding can continue over 24h if required as the gastric acidity is already altered.2. 營養液輸注速度的選擇病人由腸道曠置到重新耐受腸道內營養物質需要一段時間，因此剛開始輸注腸內營養液時應遵循低滲、少量、慢速的原則。一般間歇性輸注病人開始腸內營養時，營養液的滴速宜控制在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

10、的幅度應減慢。連續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/h ,調整滴速的依據是胃內潴留物的檢查。If a patient has not been fed in the last 5 days, feedings should begin as low volume, continuous flow feedings in the range of 25 to 50ml/hour . Dependingon the patientstolerance, the rate can be t

11、itrated upward by 25ml every 8 to 12 hours. Residual volume in stomach should be monitored every 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 must increase to make sure all requirements are met. In situations where adult

12、 patients are well established on feeding, feeds can be administered at a rate of up to 200ml/h by pump or bolus.五、營養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，經一段時間管飼營養支持后病情緩解，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，則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。六、能量、氮量及液體量的選擇Since the loss of pro

13、tein stores directly affects body function, it is important to administer sufficient amounts of energy and protein.1. 能量 腸內營養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 improving nutritional status. However, hype

14、ralimentation has beenshown to induce severe metabolic abnormalities such as hyperglycemia, hyperlipidemia, andincreased carbon dioxide production. Patients receiving nutritional support should be fed to their requirements.In clinical practice, selected methods for estimating basal energy requiremen

15、ts are shown in Box 9.1.1. A frequently used 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

16、)+66.47Female:(9.56 X W)+(1.85X 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 1.2-1.8 depending on the severity and nature of illness.Ireton-Jones energy expenditure equatio

17、nsObesityIEE =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 s

18、upport (present=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

19、into account during the calculation of the required energy needs. These include disease stress factor, activity factor, and temperature 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和他的研究小組發現選擇性手術并不增

20、加能量消耗，只有重大創傷或非常嚴重的敗血癥病人，其 能量消耗會在一定時間內增加20%40% o隨著護理和鎮痛技術的提高，與創傷有關的代謝負荷出現下降的趨勢。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。而在恢復期則應在能量消耗的基 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基礎能量消耗、體力活動消耗和疾病應激時的能量消耗。可根據Harris-Benedict公式確定BEE (見Box 9.1.1 )。再根據BEE、活動系數、應激系數、體溫系數來確定總能量的消耗，即 總能量需求

21、=BEE活動系數X應激系數X體溫系數。活動系數：臥床為 1.2 ,床邊活動為1.25 ,正常輕 度活動為1.3 。應激系數見表9-2-1 。體溫系數：正常時為1.0 ,每升高1 C增加消耗10% 。表9-2-1不同疾病狀態下應激系數疾病應激系數疾病應激系數中等程度饑餓0.851.00嚴重感染或多發性創傷1.30 1.55術后（無并發癥）1.001.05燒傷（10% 30% 體表面積）1.50癌癥1.101.45燒傷（30% 50% 體表面積）1.75腹膜炎1.051.25燒傷（ 50%體表面積）2.00長骨骨折1.151.30引自：臨床腸外與腸內營養，蔣朱明、蔡威主編，2000年際上，病人實際

22、能量的消耗通常低于由經典的公式計算出來的數值。大部分病人(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 正常人每日蛋白質的需要量一般為0.8g/kg o營養治療時為滿足蛋白質需要可增至每日1.5g/kg ,正常或輕度營養不良者按實際體重計，重度營養不良者按平時體重計，超重者則需按理 想體重計。對于危重病人，能夠滿足蛋白質合成需要、糾正負氮平衡的理想攝入量為1.51.7g/kg o由于高蛋白質飲食會增加肝、腎負擔，蛋白質的攝入量不宜超過2.0g/kg o如以能量計算，每日蛋白質攝

23、入量應占全天總能量的15%左右。另外，非蛋白質能量與氮量之比(能氮比)以(627836kJ )150200kcal:1g較為合適。能量需要下降時，能氮比也應下降。如病人需要較多蛋白質，則能氮比需降至(418502kJ ) 100120kcal:1g才能滿足蛋白質需要，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 than adequate. Wherea

24、s in the diseased patient protein synthesis can be stimulated by feeding, protein intake cannot influence whole 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/kg per day. In sev

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

26、d load, the protein intake of patient should ideally not exceed 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 may impair gastric motility and delay the use of the enteral route for feeding. Fluid r